BIOLOGICAL SOCIETY o.

BUI. I. 1. I. IN. 01. mi. BIOLOGICAL SOCIETY o.. WASHINGTON. Adl. LE3. Ebl-4. TEXT.

Editor: Richard. v.. Review. Lynne R. Parenti. Editor:. Sternberg. Reviewers: Gareth Nelson and Richard Winterbottom. Copies available as the supply. lasts. from:. The Custodian of Publications Biological Society of Washington. Museum of Natural History Smithsonian Institution Washington, D.C. 20560 National. (Cost $75.00 for the 2-volume. Cover. illustration:. (see Plate 169).. set,. including postage and handling). Pholidichthys leucotaenia, dorsal gill-arch musculature.

"This whole book. is. —nay,. but a draught. but the draft of a draft.. Herman. Melville,. ". Mobv. Dick..

STUDY OF THE DORSAL GILL-ARCH MUSCULATURE OF TELEOSTOME FISHES, WITH SPECIAL REFERENCE TO THE ACTINOPTERYGII Victor G. Springer and G. David Johnson Karolyn Darrow,. Illustrator. Appendix: Phylogenetic Analysis of 147 Families of Acanthomorph Fishes Based Primarily on Dorsal Gill-Arch Muscles and Skeleton Victor G. Springer and. (VGS, GDJ, TMO), Division of Fishes National. Museum. Thomas M.. MRC. Orrell. 159, Department of. of Natural History, P.O.. Box 37012. Washington, D.C. 20013-7012, U.S.A. e-mail: Springer.Victor@nmnh.si.edu. (KD) Department of Entomology National. Museum. MRC. of Natural History, P.O.. 105. Box 37012. Washington, D.C. 20013-7012, U.S.A. e-mail:. Darrow.Karolyn@nmnh.si.edu. Zoology.

—. The dorsal gill-arch musculature (DGM), aspects of the assoAbstract. ciated skeleton, the transversus ventralis 4, and the semicircular ligament are described for many species in over 200 families and over 300 genera of. DGM DGM. teleostome fishes, and the A partially new system of. musculature of over 200 taxa. is illustrated.. nomenclature is used. The transversus dorcomplex system than has been generally more much be a shown to is salis, data are variously analyzed and shown to be of importance recognized. for defining various currently recognized suprageneric pre-acanthomorph taxa. Among the many conclusions pertaining to acanthomorphs are: monophyly of Percopsiformes is hypothesized; Icosteidae, Menidae, and Centriscidae are probably more closely related to pre-percomorph groups than to percomorph groups; there is no basis for inclusion of Amarsipidae in the Stromateoidei; monophyly of the Polycentridae (Polycentriis, Polycentropsis, Afronandus, Monocirrhus) is corroborated based on a combination of gill-arch muscle and. DGM. additional characters.. A new ordinal-group. name, Anabantomorpha,. is. erected. to include the seven families with parasphenoid teeth: Nandidae, Badidae,. Pristolepidae, Channidae, Anabantidae, Heleostomatidae, and. Osphronemi-. dae. Anabantoidei includes the last four of these families, which have suprabranchial organs. The superfamily name Labroidea is proposed to distinguish. group of families, Labridae, Odacidae, Scarincluded in the suborder Labroidei. The first synaidae, from other families Odontobutidae is hypothesized based on the pomorphy for the gobioid family obliquus dorsalis. Certain the relative to position of the levator interims 2 or inadequately evaluunrecognized gill-arch skeletal characters previously the unequivocally monophyletic. ated are reported and discussed (e.g., epibranchial-ceratobranchial accessory cartilages; relationship of epibranchials 5 and 4; epibranchial 4 flange; esoph-. ageal raphe).. A. separately authored appendix provides a cladistic analysis of 168 taxa in and gill-arch 147 acanthomorph families based almost exclusively on study are: monoskeletal characters. Among the many results implied by the. DGM. phyly of Percopsiformes. is. Smegmamorpha Johnson and Patname is rejected for nomenclatural. corroborated.. terson (1993) are polyphyletic, and the. two or three not closely related clades: Mugilomorpha + Atherinomorpha (= Percesoces Cope, 1875), Gasterosteomorpha, and. possibly, Centrisciformes (a pre-percomorph group, comprising only Centriscidae). Gasterosteomorpha includes a monophyletic Hypoptychidae {Hypoptychus + Aulichthys), Elassomatidae, Aulorhynchidae, monophyletic Synbranchiformes (Synbranchidae + Mastacembelidae), and Gasterosteidae, thus corroborating various hypotheses of Johnson and Patterson (1993) and Johnson and Springer (1997). Labroids are monophyletic only with inclusion of Pholidichthyidae, but the group remains supported only by pharyngognath characters. Blennioidei are monophyletic and their intra-relationpurposes.. Its. constituents comprise. ships resolved. Their closest relatives are, stepwise: Gobiesocidae, Draconet(+ Callionymidae, which were not included in the analysis), Dactylop-. tidae. A new ordinal-group name, Benfhomorpha, is proposed for this clade. Caproidae are polyphyletic; relationships of its two genera appear to be with tetraodontiforms on the one hand, and acanthuroids, on the other. As such, Johnson and Patterson's (1993) hypothesis that caproid relationships are among percomorphs is corroborated. Sphyraenidae and Polynemidae form a teridae.. monophyletic group. (first. proposed by Regan, 1912)..

CONTENTS First Author's Preface. 1. Introduction. 2. Methods. 2. Material. 3. Muscles and Skeletal Elements Muscle names Muscle types Origins and insertions Anatomical orientation Transverse muscles. 3. Acanthomorph accessory. cartilages. Epibranchials 5 and 4. 3. 4 4 4 4 4 5. Abbreviations and Definitions for Anatomical. 6. Structures Classification. 16. Gnathostomata. 18. Teleostomi. 18. 18. Sarcopterygii. Coelacanthomorpha Coelacanthidae. 18. Ceratodontidae. 19. Dipnoi. 19. 21. Actinopterygii. Pre-Acanthomorpha Cladistia. Polypteridae. 21 21. 21. Pantodontidae. 22 22 23 24 24 24 24 25 25 26 27 27 28 30. Osteoglossidae. 31. Chondrostei Acipenseridae. Polyodontidae. Ginglymodi Lepisosteidae. Halecomorphi Amiidae Osteoglossomorpha Hiodontidae Notopteridae. Gymnarchidae Mormyridae Arapaimidae. Elopomorpha Megalopidae Elopidae Albulidae. Notacanthidae Halosauridae. Congridae Anguillidae. Synaphobranchidae. Clupeomorpha Denticipitidae Pristigasteridae. 32 32 33 34 36 37 37 38 39 39 39 40. Engraulidae. 41. Chirocentridae. 42. Clupeidae. 43. Gonorynchiformes Chanidae Gonorynchidae. 44 44. Cypriniformes Cyprinidae Characiformes. 46 46 48 48 49 49 49. Characidae Distichodontidae Siluriformes. Diplomystidae. Gymnotiformes Gymnotidae Salmoniformes Salmonidae. 45. 51. 51 51. 51. 53 54 Osmeridae 56 Argentiniformes 57 Argentinidae 57 Alepocephalidae 57 Platytroctidae 58 Esociformes 59 Esocidae 59 Umbridae 60 Stomiiformes 62 Diplophidae 62 Sternoptychidae 63 Gonostomatidae 63 Ateleopodiformes 64 Ateleopodidae 64 Aulopiformes 65 Aulopidae 65 Synodontidae 66 Chlorophthalmidae 66 Myctophiformes 67 Neoscopelidae 67 Myctophidae 68 Results Pre-Acanthomorpha .... 69 75-81 Tables 1-7 74 Acanfhomorpha Additional material 74 Lampridiformes 80 Veliferidae 80 Lampridae 81 Polymixiiformes 82 Polymixiidae 82 Paracanthopterygii 83 Percopsiformes 83 84 Aphredoderidae 84 Percopsidae Amblyopsidae 85 Ophidiiformes 86 Ophidiidae 86 88 Bythitidae Retropinnidae. Galaxiidae. —.

88 89 89 90 90 90. Carapidae. Gadiformes Ranicipitidae. Batrachoidiformes Batrachoididae. Lophiiformes Chaunacidae Acanthopterygii Stephanoberyciformes Gibberichthyidae. Stephanoberycidae Barbourisiidae. Rondeletiidae. Cetomimidae Icosteiformes Icosteidae. Tables 8. &. 9. Triacanthodidae. 127. Belonidae Scomberesocidae. 128. 128 129 130. 90. 131. 91. Exocoetidae. 131. Perciformes. 133. 91. Acropomatidae. 133. 92 92 93 93 94 94 94. Percichthyidae. 133. Leptobramidae. 134. Latidae. 135. Centropomidae. 135. 107. 136 137 Bathyclupeidae Symphysanodontidae .... 138 139 Epigonidae 140 Moronidae 140 Serranidae. 108. Lutjanidae. 141. 108. Haemulidae. 108. Inermiidae. 108. Apogonidae. 109. Priacanthidae. 110 110. Ostracoberycidae Cirrhitidae. 142 142 143 143 144 144. Ill. Pempheridae Glaucosomatidae. 145. 146. 98-107. Zeiformes and Possible Relatives. Zeiformes Oreosomatidae Parazenidae Zeniontidae Grammicolepidae Caproiformes Caproidae Tetraodonti formes. 127. Cyprinodontidae Beloniformes Adrianichthyidae. Hemiramphidae. 91. Melamphaidae. Aplocheilidae. Ill. Centrarchidae. 145. Meniformes Menidae. 112 112. Lactariidae. Lateolabracidae. 147. Beryciformes. 113. Sciaenidae. 147. 113 1 14. Polynemidae. 148. Sillaginidae. 115. 149 150. Trachichthyidae. Berycidae Holocentridae. Anomalopidae Percomorpha. 116. Mullidae Centrogeniidae. 117. Ambassidae. 151. Smegmamorpha. 117. Caristiidae. 152. Gasterosteomorpha. 117. Bramidae. 117. Toxotidae. 153 154. 117 118 118. Plesiopidae. 155. Percidae. 120. Callanthiidae. 156 157 158. 121. Gerreidae. 122. Grammatidae. 122 123 124 124 124 124 126 126 126 126 127. Opistognathidae. Centrisciformes Centriscidae. Gasterosteiformes Gasterosteidae. Hypoptychidae Aulorhynchidae Synbranchiformes Synbranchidae Mastacembelidae Elassomatiformes Elassomatidae. Mugilomorpha Mugilidae Atherinomorpha Atheriniformes Atherinidae. Bedotiidae. Cyprinodontifomes. Cepolidae. 151. Leiognathidae. 159 160 160 161 162. Polycentridae. 163. Sphyraenidae. 166. Pseudochromidae. Kurtidae. 167. Ammodytidae. 168 168. Trachinidae. Uranoscopidae Cheimarrichthyidae Scorpaenoidei. 169 170. 170.

171. Sebastidae. 171. Platycephalidae. Champsodontidae. 172 172. Hexagrammidae. 173. Anoplopomatidae Rhamphocottidae. 175 175. Bathymasteridae. Cottidae. 176 177. Zaproridae. 177. Stichaeidae. Normanichthyidae Carangoidei Nematistiidae. Carangidae Rachycentridae Coryphaenidae Echeneidae Scombroidei. Centracanthidae Sparidae Girelloidei. Girellidae. Kuhliidae Terapontidae Labroidei Cichlidae. Pomacentridae Embiotocidae Labroidea Labridae Pholidichthyoidei. Pholidichthyidae. Acanthuroidei. Luvaridae. Ephippidae Zanclidae Acanthuridae. Anabantomorpha Nandidae Badidae Pristolepidae. Notothenioidei. Bovichtidae. Dactylopteridae. Malacanthidae Callionymoidei Draconettidae. Callionymidae Gobiesocidae Blennioidei. 183 184 185 185 187 187 188 188 189 189. Tripterygiidae. Blenniidae. Dactyloscopidae Clinidae (Myxodinae). Clinidae (Clininae). Labrisomidae Chaenopsidae Gobioidei Rhyacichthyidae Odontobutidae Xenisthmidae. 191. 193 194. Eleotridae. Microdesmidae. 196 199. Gobiidae. 200. 202 203 203 204 204 205. 212 213 213 214 215 215 216 218 218 219 220. Pseudaphritidae Dactylopteroidei. 183. 201 201 202. 211 211 211 211. Pholidae. 181. 182 182. Lethrinidae. Zoarcoidei. 179 180. Scombrolabracidae Scombridae Nemipteridae. Amarsipidae Centrolophidae. 178. 181. Sparoidei. Stromateoidei. 177 178. Pomatomidae. 206 207 207 208 209 209 209 210. Channidae Anabantidae. Scorpaenidae. Pleuronectiformes Psettodidae. Tables 10. &. 11. Acknowledgments. .. .. .. 221 221. 222 223 224 224 225 226 228 228 229 230 233 233 194, 225 235. Appendix: Phylogenetic Analysis of 147 Families of Acanthomorph Fishes Based Primarily on Gill-arch Muscles and. 237 255. Skeleton Literature Cited Plates (separate. volume).

First Author's Preface. This study was initiated about 1996 as the primary effort of the first author. (VGS), who had long been. interested in determining the interrelationships of the. acanthomorph family Pholidichthyidae. Springer and Freihofer (1976) last discussed the problematic inter-. relationships. of the. monospecific family. then. (Springer and Larson, 1996, described a second Pholidichthys species). Subsequently, Stiassny and Jensen. (1987), expanding on the. work of Kaufman and Liem. (1982), hypothesized the composition and interrela-. acanthomorph suborder Labroidei.. tionships of an. Stiassny and Jensen based their hypothesis on a relatively broad selection of acanthomorph fishes and almost exclusively on a limited number of gill-arch. characters. Referring only to Springer. and Freihofer's. much of the descriptive poracanthomorphs, joint efforts with GDJ ceased in early 2002 at the sole instigation of VGS. VGS is responsible for selecting most of the taxa used in the study, preparing a large majority of the dissections, all the descriptions, supervision of preparation of all the illustrations, the partially new system of nomenclature used to designate the muscles, the interpretation and results of the non-acanthomorph portion of the study, most of the acanthoanalysis of the data, and. tion of the. morph. interrelationships, discussions that are not out-. growths of the cladistic analyses, all of the choices of taxa, characters, and character codes for the cladistic analyses, and preparation of all preliminary and final drafts. of the entire manuscript.. /,. VGS, there-. (1976) study, they noted similarities of the gill-arch. fore, accept full responsibility for all errors, factual. skeleton of Pholidichthys to that of the labroids.. or otherwise, and eccentricities that. Johnson (1993:9-10) discussed errors of oversight and commission in Stiassny and Jensen's (1987) study and noted, critically, that, other than characters associated with pharyngognathy, there was none that. bodies.. VGS. corroborated monophyly of the labroids.. re-ex-. amined Pholidichthys in light of Stiassny and Jensen's and Johnson's studies, and noted problems with both, although he agreed with Johnson's general crit-. As a result, VGS, with the assistance of GDJ, undertook to survey a wide variety of acanthomorph fishes to determine the distribution of the states of the muscle characters used by Stiassny and Jensen. VGS expanded the study to include a broad spectrum of non-acanthomorph fishes because of problems in determining muscle homologies among the acanthomorphs. icism.. Darrow joined. the project as full-time illustrator in. and remained on the project until which she continued on contract and. the fall of 1997. mid-2000,. after. then as volunteer until late 2003,. when. all. the gill-. arch muscle illustrations were completed.. VGS. contracted with. gram analyses of. Tom. Orrell to run. PAUP pro-. On. the other hand,. I. this study. em-. gladly share with. my. co-authors responsibility for any favorable aspects of especially want to thank. them for their encouragement and important suggestions for taxa to include, ready and comprehensive knowledge of the existing classifications of many groups of fishes and their defining characters, and his often constructive challenges, his critical reading of an early complete draft of the pre-acanthomorph section of the actinopterygian portion of the study. input:. I. GDJ. for his early. the study, early drafts of a large. number of. the acan-. thomorph descriptions and discussions, commenting on a near final draft of the pre-Appendix portion of the manuscript, and very importantly, for bringing Karie Darrow to my attention; Karie Darrow for her dedication to the project, even after monetary compensation ceased, and the unstinting use of her great illustrative talents, as well as for the numerous occasions on which she caught my descriptive mistakes; and to Tom Orrell for his insightful and knowledgeable handling of the PAUP program used in the phylogenetic. analysis,. important. suggestions. for. the. number of acanthomorph 2002, but in 2003 involved him in. preparation and interpretation of the output, and pa-. the preparation of the major cladistic analysis form-. pre-Appendix portion of the text that follows, the editorial "we" and "our" are used to accord with authorship, but their use is not intended to imply agreement by the second author.. taxa beginning in. a limited. ing our co-authored. Appendix. to the present study.. After essentially completing the actinopterygian. pre-acanthomorph portion of the study, including an. tience under stress of In the. my. importunities..

BULLETIN OF THE BIOLOGICAL SOCIETY OF WASHINGTON. The present study has two main purposes. First, to provide an annotated, descriptive atlas of the dorsal gill-arch. muscles of the extant fishes (coelacanths,. lungfishes, actinopterygians) included in the Super-. (= Grade Teleostomi, in part, of Nelson, 1994:65) or Osteichthyes (= branch 8 of Gill and Mooi, 2002:fig. 2.2) with special reference to the Actinopterygii. Second, to determine how the character states exhibited by these muscles accord with existing morphologically based phylogenetic classifications of the fishes, and to a much lesser extent, class Teleostomi. molecular-based classifications.. Because our study gill-arch. involved two ventral. initially. (notably, the semicircular liga-. structures. ment and the transversus ventralis 4), we also surveyed them. We variously include treatment of other ventral gill-arch muscles and muscles that span both. the dorsal and ventral gill-arch elements.. hand, as a result of the. way. On. did not survey the protractor pectoralis, which. is. ten closely associated with the dorsal gill-arches.. we. we. survey of. its. this. muscle see Greenwood and Lauder. In our attempts to provide accurate illustrations of. the muscles. and. their attachments,. we. also attempted. apply the same attention to the dorsal gill-arch. skeletal elements.. We. frequently illustrate and dis-. cuss skeletal structures that were previously unre-. ported or erroneously described.. On. the other hand,. we do not address all the skeletal characters that have been used in previous classifications, only those that are obvious in the illustrations, have direct bearing on the position of muscle attachments, or that by chance came to our attention (e.g., whether infrapharyngobranchial 2 is present or absent, and if present bears teeth or. is. edentate).. broad as ours, keeping up with relevant literature was a problem. Although, we attempted to do this, we recognize the possibility that references will have been missed. Another problem is that of references that became available after our discussion and analyses were in an advanced state and to adjust for them would have required continual revision and delay of the study. As far as we are aware, we have included and adjusted for the literature published through the end of 2002, and much of the literature of 2003. In a study as. Methods Dissections were. made and. from the membranes connecting them. studied primarily using. to the. opercular series and the interhyal linking them to the. hyomandibula and retained attached to the gill-archarches were released from the hyoid arches by separating the hypohyals from the basibranchials. The basihyal was then freed by making a semicircular incision around the floor of the mouth. Next, the gill filaments were stripped off while trying to assure that the external and posterior levators were not removed with them (levator externus 1 and levator posterior, require the most care to es, or, usually, the gill. avoid damage or removal). Tissue enclosing the gillarch musculature laterally was then removed. Partic-. was necessary. ular care. externus. 4,. at this point as the levator. levator posterior, and protractor pecto-. some forms. ralis in. forms). the gill-arches before. 1981).. to. arated. tissue. potential importance (for an extensive. the following procedure. First, the hyoid. arches including the branchiostegals were either sep-. tissue.. realized. were removed from speci-. In general, gill arches. mens using. of-. We. muscle was destroyed. many of. during preparation of. dissecting microscope.. the other. the study developed,. regret this omission, but the. camera lucida. As required, details were checked using a high resolution Leitz stereoscopic tached. Introduction. may be. imbedded in the and would be damaged or removed with the. A. was then made across. cut. roof just anterior to the branchial. from. clupeomorphs, lampridi-. (e.g.,. closely applied or. its. 1,. if present,. gill. the pharyngeal. arches and pharyngo-. and the. latter. was released. attachment to the skull. Muscles, ligaments,. bones, nerves, and blood vessels attaching the. gill. arches to the skull were carefully scraped or cut free.. A. cut. was then made through. the pre-pectoral area. to free the ventral attachment of the gill arches to the. body (cut passes through ventral aorta and, depending on taxon, may slice through the urohyal). From this cut, a posterodorsally arching cut was made on each side of the specimen in the tissue containing the pharyngocleithrales and attaching the gill arches to the surface of the cleithrum. The sphincter esophagi was then severed and the retractor dorsales severed from their attachments to the vertebrae. Any attached tissues (viscera, nerves, etc.) were cut and the gill arches released. The variety of taxa dissected frequently required considerable ad hoc modifications to this general procedure.. After removal, the gill arches were partially cleaned by picking away the most obvious blood vessels, nerves, viscera, and extraneous fatty and connective tissues. The gill arches were then stained. Early in the study we used a KOH-alizarin red-s solution to stain. bone and an. acetic acid-ethyl alcohol. solution of alcian blue to stain cartilage (Dingerkus. and Uhler 1977).. We. alizarin solution. was. we. found, however, that the. KOH-. destructive of the muscles and. substituted a non-destructive ETOH-alizarin so-. lution (Springer. and Johnson 2000) for. it.. Regardless. a Zeiss Operation Technoscope.. of which alizarin solution was used, the muscles usu-. using a. ally acquired a. Drawings were made Wild M-3 stereoscopic microscope with at-. pink color. or, in. the case of alcian, a.

NUMBER. 11. blue-green color, enabling one to distinguish them. ning of each descriptive account.. more. indicated, the. from one another or surrounding tissues. After staining, the muscles were further cleaned of extraneous tissues and described. Descriptions and illustrations were often done in easily. stages. In the first stage, as sible. much. information as pos-. was recorded without disturbing. other than to truncate the levators,. if. the muscles. they obscured. The muscles were then drawn. In and subsequent stages, muscles were bisected or removed in order to expose hidden muscles or muscle attachments, and at each stage, the drawing. A. the text.. mentioned in. show. additional. salis are truncated, without. mention. in. most of the. illustrations.. Some muscle. attachments were inferred without. dissection by referring to cleared and stained preparations. In so far as they. were not removed during. cleaning, ligaments and miscellaneous connective. tis-. sues are included in the illustrations and mentioned in the descriptive accounts, but the. absence of such. from the illustrations or descriptions does not necessarily imply that they are actually absent. structures. We. strove for clarity in the illustrations, at the. same time attempting. muscles as closely as possible to their actual appearance bilateral asymmetry and anomalies were included. Photographs would have been more accurate, perhaps, but to portray the. —. much. less clear.. noted. in the plate legends, are. imens.. The. The specimen. few exceptions based on single spec-. plates, with a. illustrated. may. usually the. of material (see Acanthomorpha secacanthomorphs, not otherwise. list. in the text,. was examined. for osteological. information, and served as the source for information. of 50-150. unilaterally, to. illustration is is. tion), specifically for. the next. information. Levator muscles and the retractor dor-. an. one illustrated. Occasionally, additional material examined for only one or a few characters is cited in. the other muscles.. was modified, usually. If. indicated specimen. first. Table. 8. In. general, small specimens in the range. mm. SL were selected for dissection. Depending on the taxon, these may have been adults or juveniles (some taxa rarely attain a length of even 50 as adults: specimens longer than 150 were used for taxa with proportionally small heads, e.g., eel-like forms). For many taxa, only one specimen was available for study, but even for taxa where more specimens were available, only one specimen may have been studied if the dissection was successful (i.e., little or no damage). We recognize this deficiency, but in a survey of the magnitude of the present one. we had to limit the depth of our examinations: any taxon could have been the basis for an independent study, and we dissected about 500 specimens comprising 208 families and about 400 spe-. mm. mm. cies.. Muscles are highly variable in their expression, sometimes varying bilaterally in the same individual, between individuals of the same species, or ontogenetically. Where our material and examinations permitted, and we considered the variation important, we discuss variation.. not be typical. of the taxon in every detail illustrated. For this rea-. Muscles and Skeletal Elements. son, if the reader notes a difference between a character as coded in the PAUP data matrix (Appendix. Table 12) and the representation of that character in. lustrations are listed with their definitions. the illustration, the description of the taxon should. breviations. be read for explanation. All such conflicts, however, may not be explained, e.g.. proportional or presence-. The muscles mentioned. in the text. and on the iland the ab-. we use to represent them in the section "Abbreviations and Definitions for Anatomical Structures." The skeletal elements are similarly in-. A discussion of given below because the in-. absence characters that are distorted resulting from parallax or are obscured in the view illustrated. Finally, during the course of determining obscured muscles and skeletal elements, the muscles of many. cluded, but only. of the specimens were of necessity greatly. and we use the opportunity to note new phylogenetic inferences based on the relationship of Eb5 to Eb4, ceratobranchial 4 (Cb4), and Cb5 (see section below. "Epibranchials 5 and 4"). Muscle names. There is a wealth of names available for many gill-arch muscles, but relatively few are standardized. Winterbottom (1974b) valiantly and most recently attempted a synonymy of teleost fish musculature. We utilize many of the names he recognized as senior synonyms and that are commonly employed in the literature (e.g., levator externus, or external levator). However, we also use a few names he treated as synonyms, and for many muscles we devise our own names. For these last muscles, our. damaged. removed and the specimens will be of limited or no use to future investigators. This is particularly true of specimens that were prepared early in the study using a KOH-alizarin solution to stain the bones, as the solution badly macerates the muscles, and its residue continues to do so over time. or. Material Institutional abbreviations denoting. those proposed by Leviton et. al.. specimens are. (1985) and Leviton. and Gibbs (1988). Relevant study material. is. reported at the begin-. some. epibranchial 5 (Eb5). is. are defined.. terpretation of the presence or absence of this ele-. ment. is. ductor. important. in. 5,. —. deciding the attachment of ad-.

BULLETIN OF THE BIOLOGICAL SOCIETY OF WASHINGTON have the name indicate the attachments of the muscle, e.g., musculus laminalis dentalis 5ceratobranchialis 4 (M. UP5-Cb4). a muscle originating on upper pharyngeal tooth plate 5 and inserting on ceratobranchial 4. Such names may be unwieldy, but they are descriptive, and one rarely needs intent. is. to. to refer to. them other than by. their abbreviations.. is no law of priority with regard to muscle names, and we find that despite Winterbottom's attempt to standardize muscle names, complete stan-. There. dardization in the literature has not occurred, e.g.,. names of ceratodontid muscles have not been standardized. There is the additional problem, which we have not solved, of assuring homology of usage. Our based variably on morphological topology and/or homology. If the reader is in doubt of our usage from the context of our application or disnomenclature. is. probably safest to assume topology. Muscle types. Aside from functional anatomical types (e.g., contractors, extensors), we recognize two cussion,. it. is. —. general positional types of dorsal gill-arch muscles, i.e., present on each and those that are transverse, extending from one side to the other. An interpretive problem develops when the middle portion of a transverse muscle is lost, as often occurs in acanthomorphs (e.g., transversus pharyngobranchialis 2 of Pomacentridae, Plate 160; transversus epibranchialis 2 of Embiotocidae, Plate 162.1); we have no evidence for the. those that are bilaterally paired,. scriptions are based. the deceptive appearances.. The major. Origins and insertions.. —Levators. originate. on the. cranium, or in the case of the levator posterior, may originate from the body musculature. Bilaterally paired muscles attaching pharyngobranchial elements to epibranchials and/or ceratobranchials are consid-. ered to originate on the pharyngobranchial elements. Retractores dorsales are considered traditionally to originate on the vertebral. column and. insert. on pha-. ryngeal elements. Muscles attaching an epibranchial to another epibranchial {recti dorsales. the. same. = RecD) on. side of the gill arches are considered (tra-. may be. axis of a pharyngeal element. oriented almost perpendicularly, in which case terior. end may. be described as dorsal and. its. its. an-. dorsal. surface described as posterior.. —. Interpretation of the individTransverse muscles. transversus dorsalis frecomprising the ual muscles because of the nature involved subjectivity quently. compodefinunambiguously were components nents. Some of sepwhat degree were not (e.g., able, but others pharyngotransversus components of aration of the branchialis 3 -epibranchialis 4 (TPb3-Eb4) should exist before recognizing the components as separate muscles, TPb3 and TEb4: only complete discontinuity of the components; continuity, but by only a few muscle fibers, etc.?). For some taxa, where more than one specimen was dissected, the components might be continuous in one specimen and discontinuous in another. The interpretations, therefore, contain a degree of subjectivity, which the illustrations. or degree of continuity between the various. reflect.. side,. transverse fusion of a bilaterally paired muscle).. on the anatomical position, not. Acanthomorph accessory. cartilages.. — Rosen. noted the presence of an (1984:3, 25. fig. at the joint of an epibrancartilage (AC) accessory in the gill arches of an ceratobranchial chial and 25a). first. acanthomorph (the fourth arch of Acanthurus), in which he indicated that it was of unknown significance. Rosen and Patterson (1990:9, fig. 42a) next called attention to an acanthomorph AC (in Lobotes, also in the fourth arch) and again indicated that it was of unknown significance, neglecting to mention Rosen's earlier finding. We know of no other reports of accessory cartilages. thomorphs, which. is. at the. Eb-Cb. joints of acan-. the only group in. which they. Among. acanthomorphs, Eb-Cb joint accessory occur. restricted to perciforms predominantly are cartilages occur in any gill arch, ACs may Although (Table 8). they are most. commonly. associated with the fourth. arch. In acanthomorphs having AC4, Ad5 usually. taches to. at-. it.. on the more posterior epibranchial: RecD4 originates on epibranchial 4 and inserts on epibranchial 3. Anatomical orientation. Anterior and posterior are defined by the dorsal mid-longitudinal axis of the fish that runs between the pharyngobranchials. Medial, or proximal, and distal, or lateral, are, in effect,. to pre-acanthomorphs (here further restricted to preCtenosquamata, see Table 6). Based on examination of larvae of a few taxa (Osmeridae, Osmerus, 1 7 SL; ChloroSL; Characidae, Corynopoma, >4 12-13 SL), Eb5 Chlorophthalmus, phthalmidae,. positions relative to the pharyngobranchials. Anterior. is. ditionally) to originate. —. and posterior refer to the positions relative to the head and tail of a fish, but the medial angle of articulation of epibranchials, and of the ceratobranchials with the epibranchials, often imposes an almost longitudinal orientation on them thus, the proximal and distal ends of the epibranchials deceptively appear to be the anterior and posterior ends. The de-. —. AC4. superficially resembles Eb5, which, as first. noted by Baldwin and Johnson (1996),. is. restricted. mm. mm mm. autogenous early in ontogeny (but may fuse ontogenetically with Eb4 and/or Cb4). In contrast, the acanthomorph AC4 is always associated with the distal (usually posterodistal) end of Cb4, and appears to bud off Cb4 relatively late in ontogeny. In larval. SL. Morone (Moronidae). as large as 14. mm. elements with substantial ossification and vertebral column fully differentiated and ossi(all gill-arch.

NUMBER. 1. AC4. absent and there. is no evidence of a from Cb4 from which AC4 might form. In a 28 mm SL specimen of Morone, there is a projection extending from the cartilaginous tip of Cb4, which, we presume is the precursor of the autogenous AC4 present in the much larger specimens of Morone (100 mm SL) used for the muscle descriptions. Among four cleared and stained specimens of Ambassis sp., USNM 218805, AC4 on both sides of two specimens, 30.7-35.4 mm SL, appear to be in the process of budding off; one specimen, 39.0, has autogenous AC4s on both sides, and one specimen, 45.6 mm SL, has an autogenous AC4 on one side, and a bud on the other. In a specimen of Ambassis buruensis, USNM 305331, 55 mm SL, a welldeveloped process extends posteriorly from the distal end of Cb4 with no evidence that budding off might. fied),. is. cartilaginous projection. occur.. Although we did not investigate them,. AC5. (the last. known only. AC 1-3. in Lates, Latidae). also develop as buds off the distal ends of. and. probably. CM. -3 and Cb5, with which they are very closely associated (CT surrounding the cartilaginous distal ends of the Cbs envelops the associated AC). There is a problem in polarizing the character state of AC4, but based on its appearance in Velifer, we arbitrarily treat its presence as an acanthomorph synapomorphy. Epibranchials 5 and 4. The occurrence and in-. —. Eb5 has received considerable attention (Nelson 1967d; Greenwood and Rosen 1971; Rosen 1974; Fink and Fink 1996; Johnson and Patterson 1996, 1997). It has not been established, however, that the element, which is always cartilaginous, is an epibranchial (Nelson 1969a:520, reported Eb5 was ossified on one side of one specimen of a gymterpretation of. notid).. Eb5, which. is. usually constrained as articulating. with the distal end of is. Eb4. reported to be lacking in. Nelson 1969a:520), ctenosquamates (Bald-. (e.g.. all. win and Johnson 1996:372). Eb5 varies from being completely autogenous to partially fused with the distal end of Eb4, to putatively, completely fused with the distal end of Eb4, or infrequently, as we believe, with the distal end of Cb4 (only Albula). We find that in most groups with an autogenous Eb5, the distal. it is. more. end of Cb4 than. pears to be fused with. parison with. Eb5 and. Cb4 its. closely associated with. with Eb4, and it apAlbula based on comassociation with Cb4 in. it is. in. Pterothrissus, also Albulidae).. Except for Osmerus (Osmeridae), it is problematic is always present in taxa in which the element is interpreted as partially or completely fused to Eb4. The possible alternatives are that it has been comif. Eb5. pletely lost secondarily after fusion, or lost indepen-. dently before fusion. Johnson and Patterson (1996:. 275) observed that Eb5 larvae, but. is. becomes fused. autogenous. Eb4. in. O.. mordax. Fink and Fink (1996:231) reported an autogenous Eb5 in a Gonorynchus larva, 18.5 mm SL, which is not present at later stages, but Johnson and Patterson (1997: 597), who examined Fink and Fink's specimens, were unable to find this cartilage. We also examined Fink and Fink's (1996:231) specimens (partially erroneously cited; see Johnson and Patterson 1997:597, for correct citation) and confirm Johnson and Patterson's to. in later stages.. findings.. In the plesiomorphic clupeomorph, Denticeps, the autogenous Eb5 attaches ventrally to the dorsodistal surface of Cb4 and anteroventrally to the ventrodistal end of the rod-like Eb4. In clupeoids with an autogenous Eb5, however, the element attaches ventrally to the dorsodistal end of Cb4 and articulates closely dorsally and ventrally, but not in between, with the vertically expanded mostly bony distal end of Eb4 (e.g., Dussumieria, Plate 29: B). Eb5 thus forms the cartilaginous distal border of a foramen through. which the posteriormost efferent artery passes (Nelson 1969a:520); the proximal border of the foramen is mostly bony. Based on this landmark foramen. Nelson considered that Eb5 is present in clupeomorphs in which there is no joint line dorsally between it and the dorsodistal end of Eb4. but there is one at the ventrodistal end (foramen complete), or the ventral portion of the foramen is open (foramen incomplete). Nelson did not specifically indicate the fusion of Eb5 with Eb4 in those clupeomorph taxa in which the foramen is complete or the foramen is completely surrounded by cartilage with no joint line dorsally or ventrally. One can reasonably assume (as did Rosen 1974), however, that based on the configuration of the distal end of Eb4, that Eb5 is present and that it has fused dorsally and ventrally with Eb4. There also appears to be inferential support for fusion of Eb5 and Eb4 in certain salmoniforms. In salmonids, Eb5 is either autogenous (e.g., Oncorhynchus,. Eb4. Plate 36). or,. apparently, fused dorsally with. Prosopium, foramen open ventrally; Rosen, 1974:fig. 9e). Johnson and Patterson (1997:596597) appear to accept Eb5 as present in the ostariophysan Gonorynchus based on the ventrally open fo(e.g.,. ramen. in the elongate posterior cartilaginous exten-. sion of Eb4.. Circumstantial evidence based on the attachments. of adductor 5 (Ad5) supports the probable fusion of. Eb5 with Eb4 ways attaches. in. pre-acanthomorphs: Ad5, which. al-. to. Cb5. at-. at. one end, almost always. Eb5 at the Eb4 when Eb5 is. taches to an autogenous. other end, or to. the distal end of. putatively fused. with. Eb4. (Table 6).. Probably extrapolating from the clupeomorph conditions in which Eb5 is fused dorsally to Eb4 and the foramen is open ventrally, Nelson (1967d:75, fig. Id;.

BULLETIN OF THE BIOLOGICAL SOCIETY OF WASHINGTON. Eb5 might be. pre-. applicable, in the discussions and on the illustrations. sent in the plesiomorphic osteoglossomorph Hiodon.. of the Elopocephala, but not the Osteoglossomorpha.. also our Plate 7) considered that. foramen is variable and, with the exception of Pantodon, mimics the states of the clupeoids. Only Pantodon, among the osteoglossomorphs, has an autogenous Eb5 (Plate 13B), but its articulations (one end with Cb4 and the other with an accessory cartilage attaching to Cb5) are different from those that might give In other osteoglossomorphs, the state of the. fused conditions seen er osteoglossomorphs. rise to the putatively. Excluding Albula,. Eb5 (Table. we code. in the oth-. 6):. absent. plete foramen). If the. three character states. to the. (0),. Eb5 character. states are applied. pre-acanthomorph cladogram,. it. Structures. Note: the following definitions occasionally con-. on the interpretation of. tain important caveats. muscles, *. e.g.,. —following. ER,. Eb4 or Cb4 indiEb5 with Eb4 or Cb4. See "Epibranchials 5 and 4" for discussion. a pre-acanthomorph. must be con-. section. AB — autogenous Eb4 in. bone; tiny bone attached to. thomorphs.. ACs. cartilage;. Among. at the. base of the Osteo-. glossomorpha (the autogenous Eb5, and its articulations, in Pantodon is an autapomorphy). Eb5 autogenous first appears as a basal synapomorphy in the Elopocephala. Perhaps, ontogenetic studies of the osteoglosso-. morphs will reveal, as in Osmerus, that an autogenous Eb5 is present and becomes fused with Eb4 during development. If such. Eb5. Eb4 would. is. the case, however, the. have been achieved independently by the Clupeocephala. There is another possible solution to the problem: the existing cladogram is incorrect. If Osteoglossomorpha is replaced by Elopomorpha and placed as the sister group of the Clupeomorpha. an autogenous Eb5 becomes a synapomorphy of the newly composed Teleostei, and a fused Eb4-Eb5 becomes a synfusion of. to. still. apomorphy of the Clupeomorpha + Osteoglossomorpha. The reason for suggesting these changes is that Arratia (1999), based on a limited number of recent taxa, but citing studies by other authors who used additional characters, proposed that Elopiformes are the sister group of all other Teleostei and that the Osteoglossomorpha are close to the Clupeomorpha.. The. distribution of suprapharyngobranchial. (SPbl) also makes more sense parsimoniously if the Elopomorpha exchange places with the Osteoglossomorpha in the cladogram (see discussion of LI1 in pre-acan-. thomorph Results. section).. which Ad5 attaches in which it attaches. or. "Cb4. :; .. an autogenous Eb5 from those. to a putatively (partially or comEb5 with Eb4 or Eb5 with Cb4, we latter two skeletal conditions as "Eb4*" dicate these abbreviations, where. pletely) fused. indicate the. to. ACs. morphs,. may. ACs may. are. occur in a variety. be normal or adventitious in. which they occur.. the taxon in. common,. Among. acantho-. but occur predomi-. nantly at the joint between the distal ends of an. Eb-Cb pair, hence AC1, AC2, etc, with AC4 the most common in occurrence. Except for the rarely occurring AC5, acanthomorph ACs occurring at Eb-Cb joint are not num"Acanthomorph accessory car-. positions other than at an. bered. See section. tilages" for discussion.. Ad. —. adductor, adductores. Adl, Ad2, etc., adductor. 1st arch, 2nd arch, etc; plural. Ads, Adls, etc.; muscle attaching Eb to Cb of a single arch, except Ad5, which attaches Cb5 variously to one or more of the following: Cb4, AC4, Eb4, or Eb5. Ad4 dorsal attachment is on dorsoposterior or ventral surface of Eb4, often beginning anterior to OP on Eb4 and usually extending laterally further than OP. When present, one or more of first three Ads may be completely obscured by, or fused with, an overlying gill-filament muscle (GFM, q.v.) of same arch. In general. Ads are better developed than GFMs. We occasionally had difficulty distinguishing Ads from GFMs in acanthomorphs, and subjectivity in deciding may have resulted in some. of. erroneous decisions.. Among, pre-acanthomorphs. Ads 1—3 occur only. 1. This extended discussion bears on character states for the attachment of Ad5. To differentiate states in. to acan-. (Polypterus, Atractosteus, Pantodon, Diplo-. of locations and. no evidence for the existence of an. mostly restricted. pre-acanthomorphs having. dently in the Osteoglossomorpha and Clupeoidei; is. of. Cyprinidae.. AC — accessory. mystes, Galaxias), the. independent or fused Eb5. tip. levator process and dorsal end of Eb5; only. cluded parsimoniously that state 2 evolved indepenhence, there. certain. the esophageal raphe.. cates putative fusion of. autogenous (1), and putatively partially or completely fused with Eb4 (2). State 2 is interpreted based on the appearance of the distal end of Eb4 (presence of a complete or incomfor. Abbreviations and Definitions for Anatomical. in. Polyodontidae, Notacanthidae, Cyprinidae, and. possibly Anguillidae.. They. are variably present. among acanthomoiphs, most commonly among percomorphs. It is unlikely that Adl—3 of preacanthomorphs and acanthomorphs are homologues.. It. is. unlikely, furthermore, that the acan-. thomorph Ads 1-3, which are absent in basal acanthomorphs, are serial homologues of Ad4 and Ad5 in acanthomorphs, which occur early in pre-acanthomorph phylogeny. The identification of Ad5 in various non-perci-.

NUMBER. 11. form acanthomorphs. which. in. ER. is. also present. can be problematic. In some cases, it appears that Ad5 is absent, in others Ad5 ends dorsally at a raphe with the ventral end of OP, and in others that Ad5 is present as the lateral portion of what otherwise appears to be OP. In pre-acanthomorphs,. Ad5 medially with OP ventrocommon. Additional study of ER, Ad5,. apparent fusion of laterally is. and OP is warranted. See also OP below and remarks following Ad5 in description of Arapaima (Arapaimidae).. Ad4'. —adductor 4 primus,. surfaces of in. (additional to Ad4); only. Notacanthidae.. — Cb— Bb. attaches to the anterodistal. Eb4 and Cb4. basibranchial, Bb3, Bb4, etc.; unpaired ventral. gill-arch skeletal element.. ceratobranchial; plural, Cbs; also Cbl, Cbls,. CPb. circumpharyngobranchialis; a sub-epithelial. muscle. first. described, but not named, by. Anker. (1978:261) for a cichlid muscle, and apparently not reported subsequently.. CPb. perciform fishes and. often very well developed.. It. is. appears to originate. is. present in various. from the. SO. longitudinal. muscle layer, extending anteriorly, and surrounding or only bordering, and attaching variously to. Pb2, Pb3, and UP4. In some perciforms lids,. pomacentrids) TPb2a,. may. (e.g.,. cich-. represent a dis-. Eb. —connective —. tissue.. epibranchial; plural, Ebs; also, Ebl, Ebls, Eb2,. etc.;. Eb4* in. Eb5 with Eb4; only. pre-acanthomorphs.. —. a dorsolateral or anterolateral. such that. partly. it. or completely. "shields" the cartilaginous distal end. Present only in. some percomorphs and. although flanges flanges are difficult to. much. usually restricted to Eb4,. may. be present on other Ebs. The reduced in size in many taxa (and. show on our. veloped Eb4 flange. is. A. illustrations).. present, e.g., in. all. well-de-. members. of the Labroidei, Opistognathidae, Pseudochromidae,. Grammatidae; variably developed. in Plesiop-. idae (well developed in Assessor and Paraplesiops;. weakly developed. in. Trachinops and Belo-. nepterygion; absent in Acanthoplesiops and Notograptus);. EO. in. acanthomorphs (only. involves an out pouching of the. esophagus and distal end of Eb4 is not involved. Certain anabantoid families (e.g., Channidae. Anabantidae) have a suprabranchial organ which involves modification of the. ER. —esophageal. sue or. first. epibranchial.. raphe; a fine line of connective. myoseptum. OP. usually dividing. well developed in. all. tis-. transverse-. ly at about mid-level or demarcating the ventral end of OP and separating it from Ad5 and/or SO. Very common in pre-acanthomorphs, but frequently difficult to decide the constitution of the muscle fibers ventral to ER: SO, OP, or Ad5. Relatively uncommon in acanthomorphs, but when present usually appears to separate OP ventrally from Ad5,. resulting in. Cb5. OP. (its. Cb4. attaching ventrally to. rather. usual ventral attachment in acantho-. morphs), and Ad5 attaching to Cb4 well medial to end of bone, rather than to the distal end. GC gongyloid cartilage, first named by Di Dario distal. —. (2002) and first described by him in print, but first noted by Nelson (1966a:157) in his Ph.D. dissertation; present. only in engrauloids, pristigasteroids,. and Chanos (Chanidae). See discussions in Additional remarks sections under Cetengraulis and Chanos. GFM; GFM1, 2. 3 gill filament muscle. Here con-. —. tom's (1974b:260 and. fig.. same. abductores: "extrinsic. [gill]. as Winterbot-. 26c) interbranchiales filament muscles. gill. arch (cerato- or epibranchial [we. .. .. .. would mod-. may ify this to cerato- and/or epibranchial]) gill with the [also] become intimately associated .. extension of the dorsodistal bony edge of an epi-. branchial. end of Eb4;. connecting the bases of the oral filaments to the. dorsal gill-arch skeletal element.. indicates putative fusion of. Epibranchial flange. distal. stromateoids),. sidered to be essentially the. junct portion of CPb.. CT. nous. than. ventral gill-arch skeletal element.. etc.;. erate to extraordinary expansion of the cartilagi-. atherinomorphs. except very weakly developed in belonids and absent in scomberesocids. Also very weakly devel-. rakers. .. .. .". They. gill. .. are often inconspicuous, fine, and. stringy and are frequently destroyed. ping. .. when. strip-. filaments from the gill-arches. Those of. the second and third arches in. acanthomorphs may. extend dorsoanteriorly and attach to the posterior edge of the preceding arch or they may continue. dorsomedially on the dorsal surfaces of Eb2 and Eb3, that of the second arch sometimes meeting the lateral end of TEb2. We report them only in. some acanthomorphs, and only when they. are con-. spicuous or fused with an adductor (Ad). In some taxa, they are questionably distinct from Ads (q.v.);. decision on assignment as. GFM. or. Ad. is. somewhat arbitrary. Additional study of the acanthomorph Ads and GFMs is desirable. Winterbottom (1974b:259-260 and fig. 26) also. cartilaginous distal end of. recognized interbranchiales adductores, muscles attaching to the gill filaments of both hemibranchs. the cartilaginous. of a single. oped. in the mugilid,. Agonostomus.. In labroids, the. Eb4 has been lost and end of Cb4 attaches by a tendon. EO. —. epibranchial organ; plural, EOs; in pre-acatho-. morphs usually formed,. at least in part,. gill. arch.. We. do not report on these. muscles.. to the ventral surface of the flange.. by mod-. Hb. —hypobranchial;. Hbl,. etc.;. gill-arch skeletal element.. plural,. Hbs; ventral.

BULLETIN OF THE BIOLOGICAL SOCIETY OF WASHINGTON. — only IAC — IAB. a putatively ossified IAC, and Carapidae. Synbranchidae in interarcual cartilage; usually an autogenous. arbitrarily considered absent.. interarcual bone;. rod-like cartilage joining. Ebl uncinate process. Johnson and Patterson (1996:272—275) discuss the confusion and phylogeny of uncinate and le-. vator processes on. to. Eb4 and. note that an. Eb4 un-. Pb2; found only among acanthomorphs. IAC2 interarcual cartilage 2; autogenous cartilage joining Eb2 and Pb2; only in Menidae. see GFM. Interbranchiales abductores, adductores. cinate process "characterizes acanthomorphs,". LCb. within Percomorpha. —. and. —. levator ceratobranchialis. LCb5) muscle. (i.e.,. terbottom,. who. correctly noted (in. litt.). that tro-. supplies the superior oblique muscle of the eye,. hence, inappropriately applied to a. gill. arch leva-. tor.. lat. —. lateral.. muscle on an Eb: LEI, LE2, etc.; plural LEs, LEls, etc. With rare exception (Carapidae), LEs originate on the skull, levator externus. or external. levator;. originating on cranium and inserting. posteriorly in. some. (see also LP). the. LE4 may. LE3 always. Eb3 uncinate process. inserts. EOs. on or close. Vanderwolle et al. (1998), all carapid levators originate on the medial surface of the hyomandibula. absent).. LEI. According. members. LE2', etc. levator externus 1 primus, etc.; the second of two LEls, etc., arbitrarily designated,. presumably the result of the division of an LE. Levator process (on Eb4) a cartilaginously tipped. —. The presence of an Eb4 is more common It is. frequent-. considered plesiomorphic. (e.g.,. some. specialized. Opistognathidae, Trachinidae).. levator internus or internal levator; muscle orig-. LI. inating. on cranium and. Pb2, Pb3, Pb4, UP4, or ral,. in. inserting,. UP5. Lis, LIls, etc.); LI1 inserts. some acanthomorphs;. variously,. on. LUP5, etc.; pluon Pb2 (and/or Pb3. (LI1,. especially Blennioidei,. which lack Pb2); LI2 normally. inserts. on Pb3; LI3,. absent in ctenosquamates, variously inserts on Pb3,. Pb4, UP4, UP5; LI4, only in Diplomystidae, inserts on UP4. Some confusion may arise when. comparing our Lis with those mentioned in the literature, as many authors number the LI based on the Pb to which it attaches; hence our LI1 is often referred to as LI2 in the literature, our LI2 as LI3, and our LI3 as LI4. levator internus 1 anterioris, levator inLI la, LIlp terims I posterioris; LI1 represented by two longitudinally separated muscles, both inserting on Pb2; only in Myctophidae. levator internus J primus; the posterior divi-. LI1'. sion of LI 1 inserting on ly. Pb3. anteriorly, often close-. juxtaposed to LI1 insertion on Pb2; frequently. present. LI3. (part). but not limited. in,. —. to,. Gobioidei.. a separate, probably. anomalous, basal. portion of LI3; only in Heterotis (Osteoglosso-. morpha). levator internus 3 primus; second of. LI3'. on Pb4; only. inserting. to. ',. .". .. teolabrachidae etc.) as well as in. to. is. .. percomorphs (e.g., Acropomatidae, Percichthyidae, Moronidae, Scorpaenidae, Epigonidae, Apogonidae, Serranidae, Lutjanidae, Priacanthidae, La-. in elopocephalans (ig-. noring those taxa in which the uncinate process. occasionally occur secondarily. ly present in generally. be displaced. taxa, especially those with. may. than Johnson and Patterson implied.. typically in a cluster or continuous line, usually. together with Lis; however,. it. levator process in percomorphs. originating on skull and inserting. chelar most often refers to cranial nerve IV, which. LE. although. LCb2, LCb4,. on a Cb; only in pre-acanthomorph Cyprinidae and acanthomorph Adrianichthyidae. See also remarks following LCb5 in muscle description of Cyprinidae for comment on homology. Not to be confused with LE5 of Dipnoi, which inserts on Cb5. LCb5A levator ceratobranchialis 5 accessorius; muscle originating in supratemporal fossa of skull near origin of LCb5, wrapping medially first, then anteriorly around LCb5 and inserting in CT pad attached to anterolateral surface of Cb5; only in Cyprinidae. This muscle appears to be the same as Holstvoogd's (1965:216, and fig. 12b) M. trochlearis, which Winterbottom (1974:253) synonymized with LP. It is also the same as Winterbottom's LP internus (internus and externus portions not labeled), as indicated in his fig. 22 (Cyprinus). Muscle re-named by us at suggestion of R. Win-. "Loss of a separate levator process ap-. that. pears to be a synapomorphy of Acanthopterygii,. —ligament. —. lig. LP. two LI3s. in Searsia, (Platytroctidae).. levator posterior (or levator posterioris); mostly. restricted to. acanthomorphs. but present in some. clupeoids and ostariophysans. Muscle originating variously on skull or body musculature and usually. genetically associated: process isolated. on Eb4 together with LE4. In some taxa, LE4 or coalesced in a musculous and connective tissue sheet with LE4 and/or PP. which attaches along edges of gill arches 4 and 5, and the individual muscles are not clearly separable.. cartilaginous. When LP. tilage lost. terior or. process, lateral or posterior to the uncinate process. on which LE4 and/or LP usually inserts. Presence or absence of the process may be onto(q.v.). from distal end of Eb, or, in acanthomorphs, carduring ontogeny by osseous exclusion.. In the absence of a cartilage tip, the process. is. inserting. fused with. well. is. clearly distinguished,. posteromedial to. removed from. it.. LE4. its. origin. is. pos-. origin and usually. In taxa with a single levator.

NUMBER. 9. 11. muscle on Eb4 (including, however, LE4'). that. LEs and/or Lis, there is no problem identifying the muscle as LE4 (and LE4') originates with other. because LP never clusters with the other LEs. In pre-acanthomorph taxa that have the origin of the single levator on Eb4 well posterior to those of the other levators, one might be tempted to designate the muscle LP, but examination of the muscles in related forms invariably indicates that only. present. (i.e., it. joins. LE. LE4 is LE4. cluster). Additionally,. generally inclines anteriorly, whereas. LP. frequent-. any muscle origiand inserting on an Eb could be nating on a Pb confusion. to so might cause termed an OD, but do OD2 by has been designated Our M. Pb2-Eb2 gadiforms, in which he conEndo (2002:101) for definition of obliquui dorsales,. sidered. its. presence a specialization. In pre-acan-. thomorphs, OD2 is present only in the osteoglossomorphs (Hiodon and Heterotis), where it originates on Pb3. In most acanthomorphs, the muscles we treat as obliquui dorsales originate entirely or primarily on. nachia (Gasterosteidae), and, possibly, Echenei-. Pb3 and insert on Eb3 and/or Eb4. To distinguish the acanthomorph OD2 (in Brotula, which also has M. Pb2-Eb2), we elected to denominate the "OD" originating on Pb2 as a new muscle: M. Pb2-Eb2;. dae.. likewise,. ly inclines. medially or anteromedially. Only three. acanthomorph taxa appear. to. have. lost. LE4 and. retained LP: Pholidichthys (Pholidichthyidae), Spi-. —medial. mid —middle. med. M. musculus: muscle. M. Ebl-Cbl M. epibranchialis I-ceratobranchialis 7;. muscle joining dorsomedial end of Ebl with. dorsoanterodistal end of. Cbl (only. in. Calliony-. midae).. M. Ebl-IAC. M. epibranchialis 1-cartilago interon Ebl and attaching. arcualis; muscle originating to. I. AC. M. Eb4-F inating. (only in Adrianichthyidae).. M. epibranchialis 4 faucis; muscle origon Eb4 and meshing with SO in throat. (Latin, faucis) region (only in Blenniidae).. M. Intrb M. M. Intrb 1,. intrabranchialis. (pi.. intrabranchiales);. muscle present in the CT (variously termed a diaphragm or septum) between the hemibranchs of a single branchial arch, overlain by the gill filaments, which must be scraped away to expose it. Known only for Chondrichthyes, in which they have been termed interbranchiales (Marion, 1905:905 & figs. 7. 8. 12; Daniel, 1934:105 & fig. 108) or constrictor branchiales (Edgeworth, 1935:129), and Dipnoi, in which they have also been termed interbranchiales (Furbringer, 1904:488) or constrictor branchiales (Edgeworth, 1935:129; Fox, 1965:490). Here renamed Intrb 2 etc;. to avoid confusion with the "interbranchiales" (which include interbranchiales adductores and. abductores), originally. (1974b:259. & fig.. attaching to the. named by Winterbottom. 26) for small teleostean muscles gill. filaments (see also. GFM).. Edgeworth (1935:129) erroneously reported M. Intrbs in acipenserids (see Additional remarks section under Acipenser ruthenus).. M. Pb2-Ebl. M. pharyngobranchialis 2-epibranchialis 7; muscle originating on Pb2 and inserting on Ebl; only in mormyrids and some anguilliforms.. M. Pb2-Eb2. M. pharyngobranchialis 2-epibranchialis 2; muscle originating on Pb2 and inserting on Eb2. According to Winterbottom's (1974b:253). we. designate other. "ODs". as. M. Pbs-. Ebs to avoid confusion. See also OD. M. Pb3-Cb5 M. pharyngobranchialis 3'-ceratobranchialis 5; muscle originating on Pb3 and inserting on Cb5 (only in Sparidae and Centracanthidae). M. Pb3-Ebl M. pharyngobranchialis 3 -epibranchialis 7; muscle originating on Pb3 and inserting on Ebl (only in Callionymidae). M. Pb3-Eb2 M. pharyngobranchialis 3-epibranchialis 2; muscle originating on Pb3 and inserting on Eb2 (only in Pomatomidae). M. Pb3-Eb3-Eb4 M. pharyngobranchialis3-epibranchialis 3 -epibranchialis 4; muscle originating on Pb3 and inserting on Eb3 and Eb4 (only in gobiid Gnatholepis).. M. pharyngobranchialis 3 -epibranmuscle originating on Pb3 and inserting on Eb3 (among pre-acanthomorphs, only in Novumbra, Umbridae; among acanthomorphs, at least. M. Pb3-Eb3 chialis 3;. in. some. gobioids).. M. Pb3-Eb3-Eb2. M. pharyngobranchialis 3-epi-. branchialis 3-epibranchialis 2; short muscle orig-. Pb3 and inserting on Eb3 and Eb2 (only Gymnarchidae). M. Pb3-Eb4-Eb2-Cb3 M. pharyngobranchialis 3inating on in. epibranchialis 4-epibranchialis 2-ceratobranchialis 3;. muscle originating on Pb3 and inserting on. Eb4, Eb2, and Cb3 (only in Callionymus). M. Pb3p M. pharyngobranchialis3 posterior, short cone-like muscle attaching anteriorly to Pb3 and inserting, apparently without attaching, into a concavity at the anterior end of the. first. vertebra.. Function problematic; found only in Hemiramphidae and Exocoetidae. M. pharyngobranchialis 3-phar-. M. Pb3-Pb4-Eb2. yngobranchialis 4-epibranchialis 2. —muscle. orig-. Pb3 and Pb4 and inserting on Eb2; only in the osteoglossomorph Gymnarchidae. M. Pb3-UP4 M. pharyngobranchialis 3-laminalis dentalis 4; muscle attaching to Pb3 and UP4; only inating on. in. Embiotocidae.. M. Pb4-Eb2. M. pharyngobranchialis 4-epibran-.

BULLETIN OF THE BIOLOGICAL SOCIETY OF WASHINGTON. 10. muscle originating on Pb4 and inserting on Eb2; only in notopteroids. M. SO-Pb2 M. sphinctoris esophagi-pharyngobranchialis 2; muscle originating on each side as an anterior extension of the transverse layer of the chialis 2;. sphincter oesophagi, as. it. becoming. discrete anteriorly. extends along medial side of Pbs and inserts. on Pb2 and, variously, Eb4; noted in leiognathids, but probably more widely distributed. M. SO-Pb3 M. sphinctoris esophagi-pharyngobranchialis 3; muscle originating on each side as an anterior extension of the dorsal. becoming. SO. longitudinal. and inon Pb3. More common than noted in the descriptions or on the plates as it was identified late in the study (e.g., Ditropichthys, Cetomimidae. muscle. layer,. discrete anteriorly. serting. M. sphinctoris esophagi-pharyngo-. branchialis 4; dorsolateral extension of. SO. that at-. taches to Pb4, only in Psenopsis, Centrolophidae.. M. SPb2-Eb2. M. suprapharyngobranchialis. ing ventrolaterally on. SPb2 and. 2-epi-. LE2. originat-. inserting. on Eb2;. branchialis 2; interrupted portion of. only in Acipenseridae.. is;. M. UP5-Cb4-Eb5. on UP5 and inserting at inner angle of joint formed by Cb4 and Eb5; only in characoids, but very similar to M. UP5-Cb4.. MPbl. —mediopharyngobranchial;. LE2. may comprise idei.. ObV3. obliquus ventralis 3 (not illustrated); ventral. also insert on. ODs. in. Aci-. OD3'. Acipenseridae.. M. suprapharyngobranchialis 2 medi-. alis anterioris; interrupted portion. nating on skull and inserting on. of. LE2. origi-. SPb2 anterome-. only in Acipenseridae.. dialis posterioris; interrupted portion of. LE2. orig-. and inserting on SPb2 postero-. medially; only in Acipenseridae.. —. M. transversus epibranchialis pharyngobranchialis 2. A part of TD arising from ventral surface of TEb2 and inserting on Pb2; not homologous with TPb2, which arises dorsal or anTEb2; only in Cepolidae. M. laminalis dentalis 4-epibranchialis muscle originating on UP4 and inserting on. terior to. M. UP4-Eb2. Eb2; only in Albula.. M. UP4-EM 4;. M. laminalis dentalis 4-epibranchialis muscle originating on UP4 and inserting on. Eb4; only. in. Congridae.. M. UP4-Eb5-CM. M. laminalis dentalis 4-epibranchialis5-ceratobra.nchia.lis 4 (not illustrated); muscle originating on UP4 and inserting on Eb5-Cb4. joint;. only in Megalopidae.. M. UP5-CM. (only. Diplomystes,. may. Diplomystidae). why. this. muscle. is. not considered to be an. OD2 — origin on Pb3; only in osteoglossomorphs. OD3 — insertion on Eb3 includes uncinate process, if. present.. —. Pb3. origin on. OD3. or. teriorly,. with, ventral. to,. or lateral to. OD3-4, becomes ventral to them posand attaches on Eb3 dorsally ventral or. medial to uncinate process; except for Oncorhynchus, present only in acanthomorphs.. M. SPb2Mp^M. suprapharyngobranchialis 2 me-. 2;. Pbl. and Pb4 (only pre-acanthomorphs) and Pb2 (only. SPb2; only. M. TEb2-Pb2. dorsalis (obliquui dor-. follow convention in describing these. usually originate on Pb3, but origin. sion of. skull. ODs) obliquus. reverse the origin-insertion designations.. OD.. on. Hb3 and Cb3; may. muscles as originating on Pbs and inserting on Ebs. Gareth Nelson (commenting on a draft of the MS) noted that, functionally, it is more accurate to. M. suprapharyngobranchialis 2-levator externus 1; probably a component of LE2 originating from CT on medial surface of LEI and inserting anteriorly on mid-medial surface of. inating. We. sales).. to. SCL.. acanthomorphs). Designation derives from Eb on which muscle inserts. See M. Pb2-Eb2 for discus-. M. SPb2-LEl. dially;. muscle attaching. gill-arch. lateral-. penseridae.. M. SPb2Ma. Eb 1. medial element; present only in Chanidae, Gonorhynchidae, and some Clupeosingle,. originating on skull. and inserting on SPb2 dorsolaterally; only. in. cartilage articulat-. ing posteriorly with anterior or medial end of. include. M. suprapharyngobranchialis 2. interrupted portion of. M. laminalis dentalis 5-cerato-. branchialis 4-epibranchialis 5\ muscle originating. OD — (plural,. Plate 74).. M. SO-Pb4. M. SPb2L. muscle originating on UP5 and inserting on Cb4; very similar to M. UP5-Cb4-Eb5; only in Albulidae and Gonostomatidae. chialis 4;. M. laminalis dentalis 5-ceratobran-. OD3-4. —. a complete or almost complete fusion of and OD4, essentially restricted to acanthomorphs, in which origin is usually restricted to Pb3 and insertions usually on Eb3 and Eb4 bony. OD3. surfaces supporting cartilaginous tips of uncinate processes.. OD4. —. pre-acanthomorphs originates on Pb3, in acanthomorphs originates almost exclusively on Pb3; insertion on in. Pb3 and Pb4, or Pb4;. Eb4 tip. includes bony surface supporting cartilage. of uncinate process,. if. present.. —small branch of OD4; only Heteropriacanthus OD4' — on Pb4 pre-acanthomorphs OD4v. ventral. in. (Priacanthidae).. originates. in all. except Megalops and Brycon, inates. on Pb3.. Among. in. which. only present in percopsiforms, in which inates dorsal to. OD4. posteriorly dorsal to. levator process.. or. it. orig-. acanthomorphs, OD4'. OD3-4. them and. it. is. orig-. on Pb3, extends on the Eb4. inserts.

NUMBER. OP. II. I. Eb4, usually me-. muscles attaching Cb5 to the cleithrum; both present on each side in most halecostome actinopterygians; one or both frequently illustrated in our. attachment of Ad4, but often almost. plates but usually not discussed (absence in illus-. obliquus posterioris; highly variable muscle, in as many as four parts, attaching dor-. sometimes. sally to the posterior surface of dial to dorsal. Ad4. completely overlapping. pre-acanthomorphs,. OP. is. transversely at mid-length by. few acanthomorphs. the. cussion in Ad).. SO. from. OP. most. posteriorly. In. usually interrupted. ER, and. in. most of. ER usually have OP from Ad5 (see dis-. that. separates the ventral end of. rable. medially. it,. is. frequently insepa-. or ventrolaterally from Ad5.. some pre-acanthomorph. (e.g... In. Amid) and most. acanthomorph taxa, OP is continuous, uninterrupted by ER, and attaches ventrally to Cb5 near attachment of Ad5, although OP ventromedial edge. may. join a restricted raphe with. Ad5. posterodis-. trations not intended to. Aerts (1982) reported that. all acanthomorph taxa which the muscle attachment includes the distal end of Cb5 and/or joins a raphe with OP ventrally.. in. PrO. protractor pharyngeus, anteriorly inclined. OP. com-. in cichlids. RCb5I. retractor ceratobranchialis. cle originating as. termed middle), and lateral, and that LE4 fuses with the middle OP section to form a continuous muscle extending from the origin of LE4 to the attachment of the OP middle section to Cb5. This combined muscle has been called a "sling" by Lauder and Liem 1983: 171 and Stiassny and Jen-. vertical. ). (. sen (1987:284), and. it. also occurs in (but. not. is. limited to) labrids (broad sense), embiotocids, and,. may. perhaps (our opinion) pomacentrids. and. in-. clude participation by LP. Most acanthomorphs. only give evidence of having one. probably the middle section; the divisions early in our. OP. section,. most. we may have missed. work and. further study. desirable.. obliquus posterioris primus; slender muscle. (possibly anomalous) originating on. ER. process and joining. Eb4. levator. with OP; only in Albuli-. dae.. PP. protractor pectoralis; muscle of pectoral girdle,. occasionally illustrated and/or discussed, but only. when included. in a. CT. sheet also containing, and. usually not clearly distinguishable from,. or LP.. LE4. and/. Greenwood and Lauder (1981) provide an. (commonly —pharyngobranchial "infrapharyngobranchial";. Pb. truncated spell-. ing for. venience); Pbl, Pb2,. etc.;. used for con-. dorsal gill-arch skeletal. pharyngoclavicularis,. ralis, -es),. each. -es. (or pharyngocleith-. ventral gill-arch muscle, usually. side, but. two on. only one present on each side in eels. and pre-halecostomes, but that of pre-halecostomes may be divided. See also PCE, PCI below. PCa, PCp pharyngoclavicularis anterioris, -posterioris; divisions. of the single. PC. of the pre-hale-. costome Polypterus.. PCE, PCI. 1974b:267); ventral gill-arch. 5. interims;. mus-. along dorsolateral surface of. fold abutting basioccipital process and. in. CT. pad attaching. to. Cyprinidae.. RCb5T. retractor ceratobranchialis 5 transversus; muscle originating medially from CT and SO, and inserting on dorsolateral margin of Cb5; only in Cyprinidae. Appears to be the same as retractor pharyngeus superioris of Winterbottom, 1974b: 258; fig. 22b). Only in Cyprinidae. RD retractor dorsalis; muscle usually originating on anterior vertebrae and inserting variously on one or more of Pb3, Pb4, UP4. UP5, and Eb4. Origin and insertion usually not described by us. RDs may insert anteriorly or posteriorly on Pbs.. and the difference is probably important. RDs may be unpaired, branch only at beginning of insertion, comprise a bilateral pair (one RD on each side), a bilateral pair and smaller unpaired median member (RD'), or vertical pair of muscles on each side. RD varies from being incorporated almost entirely within the. SO. muscle layer) also. (ventral to the circular or transverse to being entirely external to. SO. (see. SOD).. indicates either the unpaired. median muscle be-. tween the individual RDs dorsal muscle when RD consists of muscles on each side (see RD).. of a bilateral pair or the vertical pair of. rectus ceratobranchialis; short muscle con-. necting distal ends of two successive Cbs; only in. Callionymidae.. RecCom. rectus communis, a ventral gill-arch. mus-. cle infrequently and only incidentally appearing. in. the illustrations; not discussed in descriptions.. RecD. rectus dorsalis (plural recti dorsales); muscle. on one side with epiimmediately anterior; RecD2, RecD3,. typically joining epibranchial. branchial. pharyngoclavicularis externus, -interims. (of Winterbottom,. CT. by long tendon on. Cb5; only. RecCb. element.. SO. inserting. RD'. extensive survey of this muscle in fishes.. PC. le-. muscle originating on ventral cranial surface, extending posteriorly, and inserting on dorsal non-musculous esophageal connective tissue; present only in Neoceratodus (Dipnoi). RCb5E retractor ceratobranchialis 5 externus; muscle originating on ventral basioccipital process and inserting dorsolaterally on Cb5; only in Cyvator-like. prises three separate sections: medial, central (here. OP'. imply actual absence). PCI. or described in. is illustrated. prinidae.. tally.. is. 1. RecD4, number derives from posterior epibranchial, i.e., RecD2 originates on Eb2 and inserts on.

BULLETIN OF THE BIOLOGICAL SOCIETY OF WASHINGTON. 12. RecCom. TV4. PCE. PCI. Fig.. 1.. Ventral view of gill-arches of Pempheris schomburgkii,. greatly truncated; left-side. Bb3. joins. SCL. PCE. 318588. to. show semicircular ligament (SCL). Both RecComs tip. of posterior end of. mid-posteriorly. Photograph extensively retouched.. Eb 1 RecD 1 however, ;. USNM. almost completely removed; basihyal removed. Ventrally elongate cartilaginous. ,. originates. on Eb 1 and prob-. ten elongate and ventrally recurved.. The. ventral. ably inserts on skull or peters out in skin that roofs. aorta divides into left and right branches,. mouth; RecD5 (only Callionymus) origin includes Cb5, insertion includes various skeletal elements anteriorly. We have applied RecD to a variety of problematic muscles found in clearly unrelated taxa (e.g., Menidae, Callionymidae, Cyprinidae, Anguillidae). See also discussion following RecDs. pass anteriorly on either side of the. in Callionymus.. Bb3 attachment. RecV4. rectus ventralis 4 (Fig.. muscle attaching Cb4. SCL. to. Hb3. —semicircular ligament. 1);. ventral gill-arch. and/or SCL.. (Fig. 1); anteriorly. sections,. is. of-. to. SCL.. often obscured is. easily. to. SCL. were apparent. is. in. but because of intermediates,. SCL. tain as to. acanthomorphs,. is. and the connection. only for presence or absence.. are certain of our observation,. posteriorly to ventral surface of cartilaginous posin. Bb3. broken if. it is. attached to Bb3. Several character states for the. SCL SCL. end of Bb3, which,. to. attach-. during dissection or in trying to determine. U-shaped ligament attaching anteriorly to the ventromedial ends of Cb3 and Cb4 and, often, midterior. and RecV4 usually attach. in ventral view,. lyzed. open. ObV3. ment.. The attachment of SCL. which. Bb3. we. our dis-. we anaWhen we. report. when. attached to Bb3. In the descriptions, where. merely described as present, we are uncerwhether it was free or attached to Bb3. Stiassny (1992:269-271) discussed and illustrated is.

NUMBER. 13. 11. SCL. Her statement. SCL. that. is. an "acanthomorph. innovation" is incorrect as SCL is present in several pre-acanthomorphs (Table 1 SCL of Novumbra is especially similar to that of acanthomorphs). ;. SL, specimen lengths — standard Sling — see OP. generally recognized SO— sphincter esophagi; broad narrow SOD— sphincter esophagi. SL. are. length; all. unless indicated otherwise. as. in. the literature.. division; a. SO. to. muscle sepafrom the remainder of the transverse layer and passing dorsal to RDs. We imprecisely restrict SOD to the condition in which RD extends. band of. transverse, or circular,. rated dorsally. noticeably anteriorly external to. SOD. before en-. muscle layer (thus excluding the Aulopiformes and Ateleopodiformes as having SOD). SOD cannot be present if RD is absent, but SOD is not always present when RD is present. Although apparent in some of the acanthomorph illustrations, we may have failed to record the presence of a fine, often inconspicuous mid-ventral branch of SOD that separates the left and right tering the transverse. RDs.. SPb. Suprapharyngobranchial; dorsal gill-arch skeletal element of endochondral origin articulating with the cranium and, normally, with Ebl (SPbl) or Eb2 (SPb2); present only in Latimeria and some actinopterans (i.e., Chondrostei, Ginglymodi, Amiidae, Elopiformes, Albuliformes, and Platytroctidae).. TD. transversus dorsalis; transverse muscles attach-. ing the gill-arch elements on one side with those. on the other; not labeled as such on plates. Comprises TDA and TDP and their components. TDA and TDP muscles may be continuous and on the same level, or, most commonly in acanthomorphs TDA is somewhat dorsal to the level of TDP. TDA may be broadly or narrowly continuous with TDP or completely separate. TDP muscles may be con-. SO or SOD. Same names component muscles of TDP or TDA reported in different taxa do not necessarily imply homology; likewise, different names in different taxa may obscure homology. TDA transversus dorsalis anterior; transverse mustinuous posteriorly with for. cles. attaching to the anterior skeletal elements:. Pb2, Ebl, Eb2. (e.g.,. TEb2; Pb3 attachments. for. TDA. plexus. dian. may. attach secondarily to. an additional skeletal element, e.g., interrupted to Pb3 as well as to Eb2.. TEb2, might attach. dorsalis. posterior;. transverse. and/or to Pb3 in the (e.g.,. TPb3-Eb3); not. —slender muscle branches joined. CT. sheet dorsal to. TD; branches. Ebl, Eb2, and Eb3; only. in. to a. me-. attach to. Acanthurus (Acan-. thuridae).. TEbl. transversus epibranchialis. stricted to Labridae,. TEbl-Eb2. 1; essentially re-. Odacidae, Scaridae.. transversus epibranchialis. 1. -epibran-. Pantodon (Osteoglossoidei). TEb2 transversus epibranchialis 2. Muscle may appear to comprise two more-or-less fused segments, giving impression of twisting (see especially Gobiidae) as they pass between levators (usually LI1 and LI2) to insert on Eb2. Borden 1999) differentiated a muscle he termed TD2 from another he termed OD2 in Naso (Acanthuridae) on the basis that TD lacks a mid-line raphe and OD2 has one. Although usually present, the presence or absence of a raphe and its extent when present are highly variable, and we recognize a single muscle, TEb2, for Borden's TD2 and OD2. See also M. TEb2-Pb2. chialis 2; only in. (. TEb2a. transversus epibranchialis 2 anterioris; in. pre-acanthomorphs only in Maurolicus (Stomiiformes), variously in acanthomorphs (e.g., Pseudapocryptes, Gobiidae: labroids).. TEb2p. transversus epibranchialis 2 posterioris; in pre-acanthomorphs only in Maurolicus (Stomiiformes), variously in acanthomorphs (e.g., Pseuda-. pocryptes, Gobiidae; Dicrolene, Ophidiidae).. TEb2v in. transversus epibranchialis 2 ventralis; only. Diplophos (Stomiiformes).. TEb2-Ebl chialis 7;. transversus epibranchialis 2-epibranonly in Beiy.x (Berycidae), not to be con-. fused with TEbl-Eb2. transversus epibranchialis 3; present only in. TEb3. acanthomorphs. Except for the pre-acanthomorph engraulid genus Coilia, attachment of TD to Eb3 alone or together with another skeletal element, is restricted to Acanthomorphs, and is a synapomor-. phy of the group. TEb3-Eb4 transversus epibranchialis 3. —epibran-. chialis 4.. TEb4. transversus epibranchialis. 4.. May. be discrete. or continuous anteriorly and/or posteriorly with other muscles.. muscles, each of which. transversus. TD. TPbl-2-3-Ebl-2. acanthomorphs, the medial portion of a TDA muscle may be lost or replaced by tendinous tissue or a thick CT pad, resulting in a pair of. UP4. labeled as such on plates.. muscle. in. plates. In. TDP. ments: Eb3, Eb4, Pb4,. area joining these elements. muscles); not labeled as such on. acanthomorphs generally not reported. names. in. muscles, attaching to the posterior skeletal ele-. 3. transversus pharyngobranchialis. 1 ,2, '-epibranchialis 1,2;. only in Diplomystes (Di-. plomystidae).. TPb2. transversus pharyngobranchialis 2. In preacanthomorphs and primitive acanthomorphs, this is frequently a band-like muscle anterior to TEb2, if latter is present, and usually attaches to both Pb2s. In acanthomorphs, beginning with paracan-.