Synopsis of the Heteroptera or True Bugs
of the Galapagos Islands
4k.
RICHARD C. JROESCHNER
, D'
SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY • NUMBER 407
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Synopsis of the Heteroptera or True Bugs
of the Galapagos Islands
Richard C. Froeschner
SMITHSONIAN INSTITUTION PRESS City of Washington
1985
Froeschner, Richard C. Synopsis of the Heteroptera or True Bugs of the Galapagos Islands. Smithsonian Contributions to Zoology, number 407, 84 pages, 43 figures, 1 table, 1985. Presented are keys to species, literature and specimen records,-and list of species by island (with map). The present Heteroptera fauna contains 109 species in 61 genera; of these, Tempyra biguttula (Lygaeidae) and Tytthus parviceps (Miridae) are reported as new to the islands and the species formerly listed as Jadera sanguinolenta (Rhopalidae) is described as the new species, Jadera silbergliedi. With the exception of one species that belongs to an Old World genus, this fauna appears to be derived from American forms. One new generic synonymy is proposed: Aknisus McAtee is made a junior synonym of Metacanthus Costa, with the resulting new combination Metacanthus galapagensis (Barber).
OFFICIAL PUBLICATION DATE is handstamped in a limited number of initial copies and is recorded in the Institution's annual report, Smithsonian Year. SERIES COVER DESIGN: The coral Montastrea cavernosa (Linnaeus).
Library of Congress Cataloging in Publication Data Froeschner, Richard C.
Synopsis of the Heteroptera or true bugs of the Galapagos Islands.
(Smithsonian contributions to zoology ; no. 407) Bibliography: p.
Includes index.
Supt. of Docs, no.: SI 1.27:407
I. Heteroptera—Galapagos Islands—Classification. 2. Insects—Classification. 3. In- sects—Galapagos Islands—Classification. I. Title. II. Series.
QL1.S54 no. 407 591s [595.7'54'098665] 84-600217 [QL522.8.G34]
Page
Introduction 1 Acknowledgments 5 Key to Galapagos Families of Heteroptera 5 Synopses of Galapagos Families 7 Family ANTHOCORIDAE Amyot and Serville 7
Family BERYTIDAE Fieber 10
Family CIMICIDAE Latreille 11
Family COREIDAE Leach 11
Family CORIXIDAE Leach 12
Family CYDNIDAE Billberg 13
Family GERRIDAE Amyot and Serville 15
Family LYGAEIDAE Schilling 18
Family MESOVELIIDAE Douglas and Scott 23
Family MIRIDAE Hahn 24
Family NABIDAE Costa 39
Family PENTATOMIDAE Leach 40
Family PLEIDAE Fieber 44
Family PYRRHOCORIDAE Amyot and Serville 44 Family REDUVIIDAE Latreille 45
Family RHOPALIDAE Amyot and Serville 49
Family SALDIDAE Amyot and Serville 52
Family STENOCEPHALIDAE Dallas 53
Family TINGIDAE Laporte 54
Family VELIIDAE Amyot and Serville 56
Appendix 58 Names of Individual Islands of the Galapagos Islands 58 Map of the Galapagos Islands 59 List of Heteroptera by Islands 60 Literature Cited 63 Figures 1-43 72 Index 80
in
Synopsis of the Heteroptera or True Bugs
of the Galapagos Islands
Richard C. Froeschner
Introduction
Before one can travel to a desired destination he must gain direction by establishing his current point of existence. The aim of the present study is to establish such a point in the Heteropterology of the Galapagos Islands. In view of the limited number of Heteropterists who have done spe- cialized collecting on the Galapagos Islands and the consequent incompleteness of knowledge about their Heteroptera, the following numbers and conclusions must be considered quite tenta- tive. Much more study is needed before com- fortable confidence can be attained.
The Galapagos Islands! Magical words to the biologist! Words recalling giant tortoises, honey creeper birds, Charles Darwin, and evolution; all associated with these islands in the foundation of modern biology. Yet, study of the Heteroptera or true bug fauna of these islands has languished.
True, there have been a few lists of Heteroptera collected there, but these generally represent little more than enumerations of taxa with a smattering of fortuitous observations of habits, biology, and perhaps ecology. Exceptions to that type of study are Carvalho and Gagne's (1968) illustrated, taxonomic synopsis of the family Mir-
Richard C. Froeschner, Department of Entomology, National Museum of Natural History, Smithsonian Institution, Washing- ton, DC. 20560.
idae on these islands and the similar studies of the Saldidae by Polhemus (1968a), the Tingidae by Drake and Froeschner (1967), the Lygaeidae by Ashlock (1972), and the aquatic Heteroptera by Bachmann(1979).
The present study was begun as simply another list, this one based on a collection made in 1970 (this year generally not cited in text) by the late Robert Silberglied; but the untimely death of that talented colleague in an airplane crash de- manded a more solid contribution dedicated to his memory. Scholars who carry on biological studies of insects will find inspiration in his stud- ies and, hopefully, will find assistance in this synopsis dedicated to him.
Detailed conclusions concerning the Heterop- tera of the Galapagos Islands must be made with great caution because the state of our knowledge about the insects on those islands and elswhere in tropical America is probably quite incomplete (with many undescribed species, many relatively uncollected areas, and inadequate observations on most forms) and because of the dearth of phylogenetic analyses. A second misleading as- pect of the records of Heteroptera on the Gala- pagos Islands may result from the continued enumeration over the years of forms that, in some instances, are based on a single report made nearly a half century ago. The lack of represen- tation in subsequent collections raises the ques- 1
tion of whether or not these forms have actually maintained themselves as part of the local fauna.
The known Heteroptera fauna of the Galapa- gos Islands may be described as oceanic insular.
It is characterized by a few species (109 in 61 genera) scattered irregularly in a few families (20 of the 53) occurring on the closest continent—
South America some 900 kilometers to the east—plus the puzzling presence of a lone species from the Old World family Stenocephalidae.
The presence of these 109 species could be ac- counted for by a minimum number of 81 inva- sions (estimated by assuming whether or not the sister-species of each species developed in the Galapagos Islands) plus some speciation after cer- tain of the ancestors reached the islands. Of those 109 species, 77 are known only from the Gala- pagos Islands. A further oceanic insular charac- teristic for this fauna is the relatively restricted number of fresh-water inhabitants. Only two
"aquatic" (subsurface dwellers) families are rep- resented: the Pleidae, by a single unidentified species of the genus Paraplea; and the Corixidae, by two species of the genus Trichocorixa capable of living in saline as well as fresh waters. The
"semiaquatic" (dwellers on the water's surface) represent three families: the Gerridae, by four widespread species of the marine, water-strider genus Halobates; the Veliidae, by two species of the nearly cosmopolitan genus Microvelia; and the Mesoveliidae, by one species of the genus Darwinivelia. The presence of fresh-water forms is further mitigated against by the great aridity of the islands—a fact commented upon by Dar- win (1846) in his "Journal of Researches" carried on during the voyage of the Beagle: "The larger islands alone possess springs, and these are always situated towards the central parts, and at a con- siderable elevation." Other non-marine waters may be impounded in volcanic craters, but these lakes often have an extremely high mineral con- tent or become hot enough to kill the life in them.
Of the 56 genera of terrestrial forms occurring on the islands, 43 (77%) are represented by a single species, a fact that points to relatively little
speciation and hence leads to the conclusion of probable relatively recent invasions. In contrast, certain genera of the family Miridae and one genus of Reduviidae do exhibit marked specia- tion as three of them each have five or more species known only from this archipelago. Such speciation could have occurred because these genera have been established on the islands for a longer time or because their rate of speciation is more rapid than that of the other genera of Heteroptera that are present.
Generalized discussions of the Galapagos Is- land fauna often leave the impression of a single continuous fauna being involved. Actually some 45 separate islands and individually exposed rocks are listed for the archipelago in Wiggins and Porter (1971, table 1) who also give the estimated surface area for each. Of these islands, seven exceed 100 square kilometers (the largest, by far, being Isabela with 5847 square kilome- ters); 11 are between one and 99 square kilo- meters, and 26 are less than one square kilome- ter.
A list of the ten largest islands and the number of Heteroptera species known from each is given in Table 1. A more complete list of islands with the names of Heteroptera species reported from each is given in the Appendix.
Obviously, the number of Heteroptera re- ported from each island cannot be a reflection
TABLE 1.—The ten largest islands, each with its area and the number of Heteroptera families and species known from it (area of islands from Seltzer, 1961).
Islands Isabella Santa Cruz
Fernandina San Salvador San Cristobal Santa Maria Marchena Pinta Espafiola Baltra
Area (km2) 5847 1011 637 527 507 166 117 52 47 21
Number of families
15 18 5 11 10 9 1 4 2 4
Number of species
28 64 16 19 22 31 1 5 2 4
of island size and undoubtedly does not represent the true total of each island. These numbers are certainly no more than a reflection of the num- bers of, and interests of, collectors, which in turn may well reflect the availability and facility of collecting. For instance, Isla Santa Cruz, which is about one-fifth as large as Isla Isabela, has listed for it more than twice as many species (64 to 28) as has the latter. The explanation undoubt- edly has to include the fact that the convenient Charles Darwin Research Laboratory is on Santa Cruz. Also to be considered are means of trans- portation (frequency and types of vehicles) be- tween islands because the steep, beachless shores of some of them prevent landing from a water craft and almost demand a helicopter for access.
Predictably, some species have managed to invade several islands of this archipelago while others appear restricted to one. Such contrasting ranges are not restricted to insular species but are often duplicated by differing ranges of con- tinental forms—some species ranging virtually continent-wide while others have very restricted areas of occurrence. On the Galapagos Archipel- ago the variation in numbers from island to island clearly demonstrate (both in Table 1 listing the 10 largest islands and the more complete list in the Appendix) inconsistent and inadequate sampling of Heteroptera. The islands offer many more ecological niches than are accounted for by the known Heteroptera fauna—witness the many plants species for which none of the abun- dant phytophagous members of this insect order are reported. Much more intensive investigation is needed.
Leston (1957), in making a comparative anal- ysis of oceanic island faunas, contended that prominence of a family group on islands is occa- sioned by an innate ability of that group to col- onize detached new land surfaces (which he termed "spread potential"), rather than by the past or present geological conditions of the is- lands. He expressed "spread potential" as a num- ber by reducing the current fauna of each group to the number of ancestral invading species—in the present paper termed the minimum number
of necessary invasions—by eliminating the post- invasion speciation. His results for the four island groups thus analyzed (Azores, Guam, Hawaii, Samoa) always placed the Miridae in first place with a spread potential much higher than that of the second place Lygaeidae; in all cases the fam- ilies with the next three highest ratings were the Pentatomidae, Reduviidae, and Anthocoridae, but not necessarily in that order. The Galapagos Islands Heteroptera fauna agrees with Leston's top five families with the relative "spread poten- tial" values of Miridae, 27; Lygaeidae, 9; Penta- tomidae, 8; Anthocoridae, 7; and Reduviidae, 3.
It is interesting to note that the relative predom- inance and ranking of Miridae and Lygaeidae is the same on continental land masses as it is on islands and hence a general characteristic of those groups rather than a phenomenon associ- ated with island forms.
Available evidence certainly points to a South American origin for nearly all of the present Heteropteran population on these relatively re- cent volcanic islands. Of the 61 Heteropteran genera known from the Galapagos, all but six have representation on continental tropical America. Of these six, five are restricted to the Galapagos Islands but are related to forms oc- curring on other Neotropical lands: Darwinysius Ashlock (Lygaeidae); Galapagocoris Carvalho (Miridae); Galapagomiris Carvalho (Miridae);
Darwinivelia Andersen and Polhemus (Mesoveli- idae); and Trincavellius Distant (Pentatomidae).
The only real exception to the relationship with the Neotropics lies in the genus Dicranocephalus Hahn, a member of the family Stenocephalidae, which contains 35 species in the Old World (Eu- rasia and Africa) plus the single species restricted to the Galapagos Islands, which was first collected there by Charles Darwin during the Galapagos visit of the Beagle. As yet, there is no generally accepted theory as to how this single species could have become established on a volcanic island so far from all other members of the family.
Much needed, in addition to a list of forms occurring in an area, is information on their
natural history. Such data would permit interpre- tation of their niche in the physical environment and their role in the web of life that comprises the study of ecology. Accumulating such knowl- edge is a long, slow process requiring efforts by many persons. Recording and communicating knowledge requires names for the organisms—
names made meaningful by definitions that are understandable and applicable. Biologists fortu- nate enough to be able to visit certain areas can make intelligent records of their observations only if convenient means of identification are available. In the following synopsis of the Het- eroptera of the Galapagos Islands an attempt is made to present a summary of information avail- able (including altitude for new "Specimen Rec- ords") and identification keys that hopefully will stimulate observations and the recording thereof.
The present keys are simplified through being restricted to the genera and species known from the Galapagos Islands and by using characters visible with a hand lens of 15-20 powers. This should permit ready field identification during ecological or biological observations. The tech- nical terms used in the keys are generally those applicable to all orders of insects, but a few terms widely applied in studies of the Heteroptera and especially useful herein are shown and labeled on Figures 1-3. The formal taxonomic arrange- ment of genera is not reflected in the keys but can be determined from the text headings. Tech- nical characterizations for the latter, which are often based on more difficult or obscure mor- phological features, can be found in the supple- mental materials referred to in the text.
The incomplete knowledge about Heteroptera occurring on the Galapagos demands alertness to the limitations of the keys included for their determination. Functionally, keys are really not identification mechanisms so much as they are devices for eliminating taxa from further consid- eration—hence for telling the user what his spec- imens are not! The probability that a given spec- imen belongs to a name encountered in the key is in direct proportion to the completeness of
inclusion (assuming accuracy of the key) of the forms in the specified area. Hence accurate de- termination really requires at least one step be- yond the key, particularly one with the acknowl- edged limitations of the keys in this paper. The specimen should be compared with all critical recognition features of the putative form or, more desirably, with authentically identified specimens of that taxon. If the specimen being identified is different from that model, it may represent a new taxon or a taxon not previously known from these islands; for either condition more study is required.
This work contains a catalog of the literature records, specimen records (with new island rec- ords marked with an asterisk) from the Silber- glied collection at hand, plus a few previously unreported specimens encountered in the na- tional collection of insects (USNM) at the Na- tional Museum of Natural History, Smithsonian Institution, at Washington, D.C. To the above are added observations of natural history re- ported in the literature, a statement of general distribution, and a list of the Galapagos Islands on which that species occurs. A supplement at the end of the Appendix gives an enumeration of the Heteropteran fauna by individual island.
At the beginning of each family an introduc- tory paragraph gives a generalized review of its natural history and a paragraph on the numbers of species reported for these islands. The least number of invasions that would be required to account for their presence on this archipelago is reached by making an estimate of the location of the sister-group for each species in the archipel- ago. Obviously, some species, like mankind's traveling companion, the bed bug, could have been carried to the islands many times, but there is no reliable way to estimate that number, hence only the least necessary number is presented. A third paragraph calls attention to literature items that could be of further use in studying local forms.
The specimen records are from the California Academy of Sciences (CAS); the Los Angeles County Natural History Museum (LAM); the
Museum of Comparative Zoology, Harvard Uni- versity (MCZ); and the National Museum of Nat- ural History (the collections of the former United States National Museum), Smithsonian Institu- tion (USNM).
ACKNOWLEDGMENTS.—I acknowledge with appreciation the help of the following persons, who contributed so much to make this paper possible: Dr. Robert Silberglied and Mr. Scott Miller, for forwarding the Silberglied collection;
Dr. Charles L. Hogue (LAM) and Dr. Paul H.
Arnaud (CAS), for making specimens of their
museums available; Dr. James A. Slater, for iden- tifying the specimens of Tempyra biguttula Stal;
Dr. Thomas E. Simkin, for contributing first- hand information about the islands; Dr. Paul J.
Spangler, Dr. Joseph C. Schaffner, and Mr.
Thomas J. Henry, for reviewing the manuscript and making valuable suggestions; Ms. Silver West for typing; Mr. Young Sohn, for drawing the full figures and explanatory diagrams; Mr. George Venable, for drawing the map; and Mr. Jack Korytowski, for editing and preparing the man- uscript for publication.
Key to Galapagos Families of Heteroptera
1. Antenna shorter than head, not projecting beyond margin of head . . 2 Antenna longer than head, extending beyond margin of head 3 2. Head slightly wider than pronotum, its posterior margin sharp, broadly and deeply concave, eyes projecting posterolaterally around antero- lateral margins of eyes. Length more than 2.5 mm . . . . CORIXIDAE
[Figure 17]
Head not wider than pronotum, inserted into prothorax, eyes not projecting posterolaterally. Length 2 mm or less PLEIDAE
[Figure 12]
3. Antennae with five distinct segments. Head with a marginal carina extending anteriorly from eyes 4 Antennae with 4 segments. Head without a marginal carina from eye 5
4. Tibia with rows of stout spines CYDNIDAE
[Figure 19]
Tibia without spines, may have rows of fine hairs . . . PENTATOMIDAE
[Figure 4]
5. Last tarsal segment distinctly projecting beyond insertion of claws [see front tarsus on Figure 21] 19 Last tarsal segment not projecting beyond insertion of claws 6 6. Front wing with many small cells, dorsal surface appearing lace-
like TINGIDAE
[Figure 15]
Front wings, when present, without numerous small cells, dorsal surface not lace-like 7 7. Prosternum with sharp-sided, distinct groove along midline [Figure 40]. Beak short, more-or-less convexly curved away from venter of head, at rest its tip placed in prosternal groove [Figure 40]
REDUVIIDAE
[Figure 25]
Posternum without a groove along midline. Beak not shaped as in other half of couplet 8 8. Body extremely slender, about 7 times as long as pronotal width.
Antennae and legs linear, almost thread-like, apices of first antennal segment and of femur noticeably thickened BERYTIDAE
[Figure 23]
Body and appendages stouter than above 9 9. Eye (in dorsal view) with a deep, abrupt notch on inner margin
SALDIDAE
[Figure 11]
Eye not so notched 10 10. Wings fully developed, corium with outer apical angle set off as a
"cuneus" [Figure 1 ] by a transverse of oblique suture 11 Wings absent or variously developed, never with a cuneus 12 11. Ocelli distinct. Beak (in lateral view) arising from apex of head [as in
Figure 37] ANTHOCORIDAE
[Figure 13]
Ocelli absent. Beak arising from ventral surface of head . . . MIRIDAE [Figures 18 and 20]
12. Juga prolonged finger-like, surpassing and contiguous beyond apex of
clypeus STENOCEPHALIDAE
[Figure 24]
Juga not surpassing apex of clypeus 13 13. Wings reduced to small, transverse, oval pads (not divided into areas) across base of abdomen. Anterior margin of pronotum deeply con-
cave, broadly U-shaped CIMICIDAE
[Figure 10]
Wings, when present (subdivided into areas) longer than broad (even when not reaching apex abdomen). Anterior margin of pronotum not or only gently concave 14 14. Beak arising from apex of head, bucculae absent [as in Figure 38]
NABIDAE
[Figure 22]
Beak arising from ventral side of head between bucculae 15 15. Wings absent. First 2 segments of beak short, their combined length about half as long as head, third segment longer than head and
prothorax combined MESOVELIIDAE
[Figure 14]
Wings present. Beak with first 2 segments elongate, their combined length surpassing base of head, third segment snorter than head . 16 16. Wing membrane with not more than 5 longitudinal veins
LYGAEIDAE
[Figures 8 and 9]
Wing member with more than 5 longitudinal veins 17
17. Ocelli absent PYRRHOCORIDAE
[Figure 7]
Ocelli present, distinct 18
18. Side of thorax between middle and hind leg with a conspicuous rounded pore bordered by distinct elevations [Figures 2 and 3]. Galapagos species with a long, outcurved spine on side of head between eye and
antennal tubercle COREIDAE
[Figure 5]
Side of thorax without a visible pore. Head without spine described in
other half of couplet RHOPALIDAE
[Figure 6]
19. Middle coxa equidistant from front and back coxae. Posterior femur less than half as long as length of body VELIIDAE
[Figure 16]
Middle coxa much closer to back coxa than to front coxa. Posterior femur as long as or longer than length of body GERRIDAE
[Figure 21]
Synopses of Galapagos Families Family ANTHOCORIDAE Amyot and Serville
(Minute Pirate Bugs)
These usually small insects are vivid predators on other insects, hence their common name.
They may attack soft-bodied adults, immatures, or eggs of several orders of insects. Some mem- bers of the family have been reported repeatedly from bird nests but their role in that ecological niche has not been ascertained. Occasionally a minute pirate bug will use its beak to probe the skin of man and may cause him a sharp but rarely prolonged sensation. None of them are known to derive their nourishment from warmblooded sources.
The Anthocoridae fauna on the Galapagos consists of seven species, each in a different ge- nus. Two of them are cosmopolitan species that apparently have accompanied man to many parts of the earth. Of the other five, four also occur
in Central and South America, while the last one, Nidicola mazda, is known only from the Galapa- gos but belongs to a genus otherwise ranging from the United States south into Mexico. This information, plus the fact that only two of the species occur in the West Indies, suggests a con- tinental tropical origin for this fauna rather than one involving the West Indies as was suggested by Herring (1966a: 130) for these same seven species. Because each of the seven species is in a separate genus the assumption must be made that the sister-group of each is non-Galapagos and that the least number of invasions necessary to result in this fauna is seven.
The supergeneric classification now followed in this family is the one proposed by Carayon (1972) who greatly modified the arrangements by Reuter (1884) and by Poppius (1909). There is no key to all the Western Hemisphere genera of Anthocoridae, but Herring's (1976:143-150) key to the North American genera encompasses the seven known from the Galapagos.
Key to Galapagos Genera of Anthocoridae
Greatest diameters of antennal segments II, III, and IV equal. Hairs on antennal segments III and IV less than twice as long as diameter of supporting segment Orius Wolff Antennal segments III and IV distinctly thinner than II and with long erect hairs, most of which are at least twice as long as diameter of supporting segment 2
2. In dorsal view, lateral margin of pronotum laminately expanded for full length, width of expansion more than half as wide as first antennal segment Nidicola Drake and Harris In dorsal view, lateral margin of pronotum not expanded 3 3. Clavus and scutellum with numerous distinct punctures which are some- times darkened 4 Clavus and scutellum without punctures (although short hairs may suggest punctures) 5 4. Lateral margin of pronotum and costal margin with crowded long hairs projecting laterally and horizontally. Pronotal calli laterally reaching lateral pronatal margins, not limited by a longitudinal submarginal impression Lasiochilus Reuter Lateral margin of pronotum and costal margin without long horizontal
hairs. Pronotal calli abruptly delimited laterally . . Amphiareus Distant 5. Pronotal surface smoothly convex, without a prominent transverse impression posterior to calli. Corium whitish hyaline, color contrasting sharply with polished reddish brown of head, pronotum and scutellum Xylocoris Dufour Pronotal disc with a distinct transverse impression posterior to calli.
Corium not whitish hyaline 6 6. Metapleural scent trough (peritreme) short, curved caudad, attaining middle of posterior margin of dull roughened evaporating surface [Figure 32] Alofa Herring Metapleural scent trough long, gently curved anteriorly, more or less paralleling posterior margin of dull roughened evaporating area and reaching its lateral margin [Figure 31] Cardiasthethus Fieber Subfamily ANTHOCORINAE Amyot and
Serville Tribe ORIINI Carayon
Genus Orius Wolff
Orius Wolff, 1811:161 [type-species: Salda nigra Wolff, orig- inal designation].—Herring, 1966b: 1093-1109 [revision of New World forms with key to species].
Orius tristicolor (White)
Triphleps tristicolor White, 1879:145 [United States of Amer- ica (type)].
Orius tristicolor.—Herring, 1966a: 130 [Santa Cruz].—Lin- sley, 1977:12 [Santa Cruz].
DIAGNOSIS—Dorsum with hair inconspicuous.
Head, pronotum, scutellum and clavus wholly dark brown to black, contrasting sharply with remainder of the opaque, ivory white corium.
Outlines of calli, except where fused to each other mesally, sharply distinct. Length 1.8-2.1 mm.
GENERAL DISTRIBUTION.—North, Central, and South America; West Indies; Galapagos Is- lands.
GALAPAGOS DISTRIBUTION.—May. Santa Cruz.
Subfamily LASIOCHILINAE Carayon Genus Lasiochilus Reuter
Lasiochilus Reuter, 1871:562 [type-species: Lasiochilus palli- dulus Reuter, only included species].
Lasiochilus pallidulus Reuter, 1871
Lasiochilus pallidulus Reuter, 1871:562 [United States of America (type)].—Herring, 1966a: 128 [Santa Cruz].—
Schaefer et al., 1980:46 [Santa Cruz].—Froeschner, 1981:12 [Galapagos Islands].
DIAGNOSIS.—Dorsum of head, pronotum, and corium nearly concolorous. Calli contiguous ex- cept for short separation near base by a narrow longitudinal impression. Claval punctures (some- times embrowned) distinctly coarser than nearly all other punctures over remainder of corium.
Length 2.2-2.8 mm.
DESCRIPTION.—Some individuals are wholly pale while others have a conspicuous area of fuscous laterally on the scutellum and on anten- nal segment II.
SPECIMEN RECORDS.—Santa Cruz: Academy Bay, 13 Mar 1970, about 5 m.
GENERAL DISTRIBUTION.—North and Central America; West Indies; Galapagos Islands.
GALAPAGOS DISTRIBUTION.—Feb-Mar. Santa Cruz.
Subfamily LYCTOCORINAE Reuter Tribe CARDIASTETHINI Carayon
Genus Alofa Herring
Alofa Herring, 1976:150 [type-species: Cardiastethus sodalis White, only included species].
Alofa sodalis (White)
Cardiastethus sodalis White, 1878:372 [Hawaiian Islands (type)].
Buchananiella sodalis.—Herring, 1966a: 127 [Santa Cruz].—
Linsley, 1977:12 [Santa Cruz].
Alofa sodalis.—Froeschner, 1981; 13 [Galapagos Islands].
DIAGNOSIS.—Most of clavus and corium basad of cuneus distinctly paler than rest of dorsum.
Length 1.7-2.0 mm.
REMARKS.—This widespread species appar- ently has traveled to many parts of the world on man's transportation vehicles.
GENERAL DISTRIBUTION.—Almost cosmopoli- tan: North, Central, and South America; the West Indies; Africa; many Pacific Islands.
GALAPAGOS DISTRIBUTION.—Jan. Santa Cruz.
Genus Amphiareus Distant
Amphiareus Distant, 1904b:220 [type-species: Xylocoris ful- vescens Walker, a junior synonym of Xylocoris constrictus Stal, only included species].
Amphiareus constrictus (Stal)
Xylocoris constrictus Stal, 1860:44 [Brazil (type)].
Buchananiella constrictus.—Herring 1966a: 127 [Santa Cruz].—Linsley, 1977:12 [Santa Cruz].
Amphiareus constrictus.—Froeschner, 1981:13 [Galapagos Is- lands].
DIAGNOSIS.—Dorsum dirty yellow, apex of corium often with an oblique brown blotch.
Pronotum with transverse impression behind calli extending across full pronotal width. Length 2.1-2.4 mm.
GENERAL DISTRIBUTION.—Almost cosmopoli- tan: North, Central, and South America: the West Indies; Africa; the Orient; and many islands of the Pacific Ocean.
GALAPAGOS DISTRIBUTION.—Mar. Santa Cruz.
Genus Cardiastethus Fieber
Cardiastethus Fieber, 1860:39, 141 [type-species: Cardiaste- thus luridellus Fieber, designated by Kirkaldy, 1906:121].
Cardiastethus limbatellus (Stal)
Xylocoris limbatellus Stal, 1860:44 [Brazil (type)].
Cardiastethus limbatellus.—Herring, 1966a: 127 [Santa Cruz].—Linsley, 1977:12 [Santa Cruz].—Froeschner, 1981:13 [Galapagos Islands].
DIAGNOSIS.—Dorsum blackish with head, lat- eral margins of pronotum, and costal margins reddish. Elytra, except clavus, densely but finely punctured. Length 2.3 mm.
GENERAL DISTRIBUTION.—Guatemala, Brazil, Galapagos Islands.
GALAPAGOS DISTRIBUTION.—Jan-Mar. Santa Cruz.
Tribe SCOLOPINI Carayon Genus Nidicola Harris and Drake
Nidicola Harris and Drake, 1941:343 [type-species: Nidicola marginata Harris and Drake, only included species].—
Drake and Herring, 1964:53-63 [revision of genus with key to species].
Nidicola mazda Herring
Nidicola mazda Herring, 1966a: 129 [Galapagos Islands:
Santa Cruz (type)].—Linsley, 1977:12 [Santa Cruz].—
Froeschner, 1981:13 [Galapagos Islands].
DIAGNOSIS.—Pronotum with surface strongly rugulose; its anterolateral angles not projecting anterior to collar. Corial veins slightly elevated.
Length 1.7 mm.
GENERAL DISTRIBUTION.—Galapagos Islands.
GALAPAGOS DISTRIBUTION.—Jan. Santa Cruz.
Tribe XYLOCORINI Carayon Genus Xylocoris Dufour
Xylocoris Dufour, 1831:423 [type-species: Xylocoris rufipennis Dufour, a junior synonym of Anthocoris cursitans Fallen, only included species].
Xylocoris sordidus (Reuter)
Piezostethus sordidus Reuter, 1871:560 ["USA"; Brazil].
Xylocoris sordidus.—Herring, 1966a: 130 [Galapagos Islands:
Baltra, Santa Cruz].—Linsley, 1977:12 [Baltra, Santa Cruz].
DIAGNOSIS.—Corium mostly whitish (often with cuneus and costal margin or more darkened), contrasting sharply with polished red- dish brown of head, pronotum, and scutellum.
Length, 2.7-3 mm. (See Figure 13.)
SPECIMEN RECORD.—Santa Cruz: Darwin Re- search Station, 23 Feb 1970, about 5 m.
GENERAL DISTRIBUTION.—North, Central, and South America; West Indies; Galapagos Is- lands.
GALAPAGOS DISTRIBUTION.—Jan-Feb. Baltra, Santa Cruz.
Family BERYTIDAE Fieber (Stilt-legged Bugs)
Members of this family move over the plant surfaces without efforts at concealment other
than that afforded by their stick-like body and thread-like appendages. They have been re- ported feeding on plant sap or on the body juices of soft-bodied insects, such as aphida, or on insect eggs. Stilt-legged bugs glue their eggs directly to plant surfaces or place them on slender stalks.
The single species known from the Galapagos Islands belongs to the widespread genus Metacan- thus, which has been found on all continents and many islands. As the only member of the family on the islands, its presence could be accounted for by a single invasion.
The literature for this family is much scat- tered. Generic keys to aid studies of Neotropical, stilt-legged bugs can be found in Stusak and Cobben (1975) and in Froeschner (1981).
Genus Metacanthus Costa
Metacanthus Costa, 1844:258 [type-species: Berytus elegans Costa, only included species].
Aknisus McAtee, 1919:81 [type-species: Aknisus calvus McAtee, original designation; new synonym].
DIAGNOSIS.—Pronotum with neither spines nor white tubercles on anterior lobe. Ostiolar peritreme with a distinct longitudinal groove on dorsum of curved apical part.
REMARKS.—Froeschner (1981:16-13) keyed Metacanthus Costa and Aknisus McAtee in the same half of a couplet because he was unable to separate them. Additional considerations lead to the conviction that they are indeed congeneric with Costa's generic name having priority. New Synonymy.
Metacanthus galapagensis (Barber), new combination
Jalysus (Metacanthus) tenellus.—Heidemann, 1901:366 ["mis- identification"; Galapagos Islands: San Cristobal].
Aknisus galapagensis Barber, 1934:284 [Galapagos Islands:
San Cristobal (types)].—Linsley and Usinger, 1966:134 [San Cristobal].—Froeschner, 1981:17 [Galapagos Is- lands].
DIAGNOSIS.—Antennal segment II slightly more than 3 times as long as II. Antennal seg- ments I and II and legs faintly banded and spot-
ted with brown. Length, 5-5.7 mm. (See Figure 23.)
SPECIMEN RECORDS.—Santa Cruz*: Bellavista, 5Jun, 170 m., on Datura. These specimens agree well with the holotype.
GENERAL DISTRIBUTION.—Galapagos Islands.
GALAPAGOS DISTRIBUTION.—May-Jun. San
Cristobal; Santa Cruz*.
Family CIMICIDAE Latreille (Bed Bugs)
Members of this family are strongly marked by having their wings reduced to mere pads or less. They have a specialized diet of blood from warm-blooded hosts, whether these be birds or mammals, including man. Theoretically these in- sects first associated with cave-dwelling animals, including man in his earliest history. Some of the species accompanied man wherever he went.
The only species of Cimicidae reported from the Galapagos is the common, domestic bed bug which doubtless was carried to the islands by persons who came to visit or to live. A single record is the basis of all subsequent reports of it on these islands. While it is quite probable that ships from the earliest visits have brought it to the islands several times, the conclusion is self- evident that the least numbers of invasions nec- essary to bring a species to the islands is one!
Usinger's( 1966) monograph of the family pro- vides a fully illustrated treatment with many de- tails on all species, including much information on the biology, ecology, habits, and other aspects of their lives.
Subfamily CIMICINAE Latreille Genus Cimex Linnaeus
Cimex Linnaeus, 1758:441 [type-species: Cimex lectularius Linnaeus, designated by Opinion 81 of the International Commission on Zoological Nomenclature (1924:19)].
DIAGNOSIS.—Posterior coxa separated from each other by a flat plate between coxae. Tibia uniformly colored, not mottled. Length of anten-
nal segment II nearly or quite equal to interoc- ular width.
Cimex lectularius Linnaeus
Cimex lectularius Linnaeus, 1758:441 [Europe (type)].—Bar- ber, 1934:281, 287 [Santa Maria].—Linsleyand Usinger,
1966:135 [Santa Maria].—Usinger, 1966:251, 313 [Ga- lapagos Islands, see map, fig. 11-2].—Froeschner,
1981:18 [Galapagos Islands].
DIAGNOSIS.—Pronotum 2'/2 times wider than long. Antennal segment II slightly more than one-third of width of head. Length, 4.9-6.0 mm.
(See Figure 10.)
REMARKS.—This pest, the infamous bed bug, has followed man wherever he has gone, hence its presence on these islands was not unexpected.
What is surprising is that the single record by Barber (1934) obviously serves as the basis for all subsequent listings for the islands. Apparently the insect was unable to maintain a population either because too few humans lived on the is- lands or because man's efforts to eliminate it were effective.
GENERAL DISTRIBUTION.—Cosmopolitan.
GALAPAGOS DISTRIBUTION.—Dec. Santa Maria.
Family COREIDAE Leach (Coreid Bugs)
Members of this family derive their nourish- ment from a variety of plants, sometimes includ- ing man's crops. Many of the members emit an odorous fluid that in part may be defensive as all stages from eggs to adults are exposed on plant surfaces.
A single species of Coreidae is known from the Galapagos Islands. It was described from speci- mens collected by Charles Darwin during his historic visit. Because this species is known only from the Galapagos Islands it must represent the modified descendants of a form that reached the islands at an earlier time—the single invasion necessary to establish the Coreidae line on the islands. Its genus, Anasa, is restricted to the New
World so the ancestors of this sole representative on these islands must have come from the Amer-
icas.
The suprageneric classification of the family Coreidae is now undergoing a much needed re- vision that will not reach publication in its final form for some time.
Subfamily COREINAE Leach Tribe SYROMASTINI Stal Genus Anasa Amyot and Serville
Anasa Amyot and Serville, 1843:209 [type-species: Anasa cornuta Amyot and Serville, only included species].
DIAGNOSIS.—Head less than half as wide as pronotum; postocular margin over half as long as eye, distinctly calloused. Veins of membrane lengthwise, not uniting to form small cells.
Anasa obscura Dallas
Anasa obscura Dallas, 1852:505 [Galapagos Islands (type)].—Dohrn, 1859:30 [Galapagos Islands].—Stal, 1870:197 [Galapagos Islands].—Butler, 1877:88 [Gala- pagos Islands].—Lethierry and Severin, 1894:76 [Gala- pagos Islands].—Heidemann, 1901:365 [San Cristo- bal].—Champion, 1924:260 [Galapagos Islands].—Bar- ber, 1934:283 [San Cristobal].—Linsley and Usinger, 1966:133 [San Cristobal].—Froeschner, 1981:25 [Gala- pagos Islands.]
DIAGNOSIS.—Head with a long (longer than eye), tapering, outcurved spine above base of antenna; without a median pale line. Antenna wholly pale. Pronotum with anterolateral angles not projecting. Length, 10-10.6 mm. (See Fig- ure 5.)
SPECIMEN RECORDS.—Isabela*: Volcan Al- cedo, east to south rim, 20 Mar 1970, 925 m.
Santa Cruz*: Cerro Crocker, summit area, 7 Jul, 860 m, "grassy zone."
GENERAL DISTRIBUTION.—Galapagos Islands.
GALAPAGOS DISTRIBUTION.—Mar, May, Jul.
Isabela*, San Cristobal, Santa Cruz*.
Family CORIXIDAE Leach (Water Boatmen)
These aquatic insects spend most of their time under water clinging to submerged objects by their middle legs. In a space between their elytra and concave abdominal dorsum they carry a sup- ply of air that serves not only as a source of oxygen but also gives them bouyancy for rising quickly to the surface when new air supplies are needed. They again return to their underwater environment by powerful sweeps of their flat- tened and fringed hind legs. Characteristically they are microphagous, feeding on diatoms, algal cell contents, and other such tiny sources of nourishment; in contrast, some species are re- ported as feeding on mosquito larvae. Eggs are glued to shallowly submerged objects. Most forms frequent only fresh water but some, as was first pointed out by Hutchinson (1931:573) for the genus Trichocorixa, can complete their life cycles in brackish waters. Thus it is possible for certain species to occur on the Galapagos Islands where there are few permanent bodies of fresh water.
The two species occurring on the Galapagos Islands belong to one genus that ranges from the Hudson Bay area in Canada south into north- western South America. The range of one species is from southern United States south to Peru.
The other species was described as being "clearly derived from" the first (Sailer, 1948:308). This relationship suggests that only a single invasion was necessary to account for the presence of both species.
The most useful paper for the study of the family Corixidae as it is known to occur on the Galapagos Islands is Hungerford's (1948) mon- ograph of the Western Hemisphere Corixidae, which contains a revision of the genus Trichoco- rixa by Sailer. This work was reprinted in 1977 almost exactly as in the original except for a correction in the key to the species of Trichocorixa and a new section updating the reference litera- ture.
Subfamily CORIXINAE Leach Tribe CORIXINI Leach Genus Trichocorixa Kirkaldy
Arctocorisa (Trichocorixa) Kirkaldy, 1908:118 [type-species:
Corisa pygmaea Fieber, only included species].
Trichocorixa.—Hungerford, 1927:96.—Sailer, 1948:289- 407 [revision, key (corrected in 1977 reprint) to species on pages 302-305].
DIAGNOSIS.—Pronotum with posterior margin
projecting caudad as an apically rounded triangle nearly or quite covering scutellum. Pronotum and front wings with transverse black lines, these sometimes irregular or broken.
REMARKS.—The Silberglied Collection con- tains seven badly shriveled, early instar, nymphal corixids from Isla Isabela. These are unidentifi- able, but for the time being they may be consid- ered to belong to this genus, the only one known to occur in the Galapagos Islands. They were collected at Tagus Cove, 22-23 March, "in crater lake."
Key to Galapagos Species of Trichocorixa
Length of pala (blade-like, modified, anterior tarsus) equal to length of posteroventral margin of eye [Figure 39]. Length 3.0-3.2 mm T. beebei Sailer Length of pala two-thirds as long as posteroventral margin of eye. Length
2.8-5.2 mm T. reticulata (Guerin-Meneville) [Figure 17]
Trichocorixa beebei Sailer
Trichocorixa beebei Sailer, 1948:306 [Galapagos Islands: Gen- ovesa (type)].—Froeschner, 1981:28 [Galapagos Islands].
GENERAL DISTRIBUTION.—Galapagos Islands.
GALAPAGOS DISTRIBUTION.—Genovesa.
Trichocorixa reticulata (Guerin-Meneville)
Corisa reticulata Guerin-Meneville, 1857:423 [Cuba (lecto- type designated by Sailer, 1946:618)].
Trichocorixa reticulata.—Sailer, 1946:617 [Galapagos Is- lands]; 1948:343 [San Salvador, Santa Cruz].—Linsley and Usinger, 1966:136 [Galapagos Islands].—Nieser, 1969:153 [San Salvador, Santa Cruz]; 1970:66 [Galapagos Islands]; 1975:217 [Galapagos Islands].—Lauck, 1979:101 [Galapagos Islands].—Bachmann, 1979:134 [Is- abela, Santa Cruz].—Froeschner, 1981:28 [Galapagos Is- lands].—Jansson, 1982:101 [Galapagos Islands].
SPECIMEN RECORDS.—Santa Cruz: Academy Bay, Darwin Research Station, 13 March, 5 m,
"at ultra violet blacklight."
GENERAL DISTRIBUTION.—Southern North America through Central America and the West
Indies onto northern South America; Galapagos Islands. Introduced into Hawaii.
GALAPAGOS DISTRIBUTION.—Mar, Jul, Oct.
Isabela, San Salvador, Santa Cruz.
Family CYDNIDAE Billberg (Burrowing Bugs)
The characteristic habit of nymphs and adults burrowing in the ground and feeding on the roots of plants is almost family-wide, the most marked exception being in the subfamily Sehiri- nae, where adults and nymphs feed on above- ground parts of plants. Adults of the burrowing forms come to the surface to mate and to disperse and at that time freely fly to lights. Eggs are laid in the soil. As reported below for one of the Galapagos species, specimens (adults and nymphs) of this family are often found in caves.
Their entry into the caves probably results from the positive geotropic reactions leading the bug down along the roots on the soil forming the roof of the cave rather than from horizontal
travel from the mouth of the cave. The fate of the populations that enter the caves is not known.
Are the individuals that comprise it capable of adapting to a diet of organic debris or bat guano accumulated on the cave floor? Can they reverse their regular root-seeking positive geotropic re- action and return to the cave roof to find their regular food source, or are they individually doomed to dwell their life in total darkness and to leave no successful progeny? Several instars have been reported as probing bat guano with their beak; but whether this was simply explora- tion of damp substance or actual ingestion of nourishment was not determined.
Each of the two species reported from the Galapagos Islands belongs to a separate genus occurring on the New World continents. One species was formerly thought to be restricted to
the Galapagos Islands but is now known from the coastal areas of Ecuador, where it apparently is a relatively recent introduction. The other spe- cies is a North American form reported only once for the Galapagos Islands; that record may represent an adventive or mislabeled specimen.
Thus the family is represented on those islands by minimum invasions of one or two ancestors, depending upon the status of the second species mentioned above.
The most recent monograph of the species of Cydnidae of the Western Hemisphere is that of Froeschner (1960). A different family-subfamily classification was offered by Dolling (1981) who returned to an earlier, more inclusive concept of the family that encompassed several groups, like the thyreocorids, as subfamilies. Herein the for- mer study is followed.
Key to Galapagos Genera of Cydnidae
In ventral view ostiolar pore visible, peritreme laterad of it with a polished lobe Melanaethus Uhler In ventral view ostiolar pore concealed, peritreme in no part polished
Dallasiellus Berg Subfamily CYDNINAE Billberg
Genus Dallasiellus Berg
Stenocoris Signoret, 1880:lxiv [preoccupied; type-species: Ae- thus longulus Dallas, only included species].
Dallasiellus Berg, 1901:281 [proposed as a new name for the preoccupied Stenocoris Signoret, hence takes the same type-species].
Dallasiellus murinus (Van Duzee)
Geotomus murinus Van Duzee, 1933:26 [Galapagos Islands:
Tagus Cove, Isabela Island (type)].—Barber, 1934:282 [Isabela].
Dallasiellus (Dallasiellus) murinus.—Froeschner, 1960:616 [Isabela, San Cristobal].
Dallasiellus murinus.—Linsley and Usinger, 1966:133 [Isa- bela, San Cristobal].—Froeschner, 1968:192 [Fernan- dina, Isabela, San Cristobal, Santa Cruz, Santa Maria];
1980:2 [Isabela, Santa Cruz]; 1981:31 [Galapagos Islands].—Linsley, 1977:10 [Fernandina, Isabela, San
Cristobal, Santa Cruz, Santa Maria].—Schaefer et al., 1980:44 [Fernandina, Isabela, Pinta, San Cristobal, Santa Cruz, Santa Maria].
DIAGNOSIS.—Head dorsally with well scat- tered minute punctures; preocular margin dis- tinctly carinate; jugum longitudinally weakly con- cave. Scutellum discally with coarse punctures.
Length 5.0-5.5 mm.
SPECIMEN RECORDS.—Santa Maria: 17 Feb 1964, forest floor at 300 m; Santa Cruz, remains in a cave on floor.
On the Galapagos this species has been taken from under bunch grass and litter and, as could be anticipated, from lights.
GENERAL DISTRIBUTION.—Galapagos Islands and Ecuador.
GALAPAGOS DISTRIBUTION.—Nov-Apr. Fer- nandina, Isabela, Pinta, San Cristobal, Santa Cruz, and Santa Maria.
Genus Melanaethus Uhler
Melanaethus Uhler, 1876:280 [type-species: Melanaethus elongatus Uhler, a junior synonym of Aethus subglaber Walker, only included species].
Melanaethus subglaber (Walker)
Aethus subglaber Walker, 1867:150 ["North America"].
Melanaethus subglaber.—Froeschner, 1960:438 [Marchena];
1968:192, [? Marchena]; 1981:31 [? Galapagos Islands].—
Linsley, 1977:10 ["Marchena (?)"].
DIAGNOSIS.—Pronotum with submedian transverse impression impressed distinctly and equally across full width of pronotum. Preocular margin of head with a distinct carina. Head dor- sally with numerous crowded punctures. Length 3.1-3.5 mm.
REMARKS.—Froeschner (1968:192) suggested the specimen that forms the basis for including M. subglaber in the Galapagos fauna was perhaps mislabeled. Until negative evidence can be de- rived from more specialized collecting on the Island of Marchena, the species should be consid- ered, at least tentatively, as occurring on that island.
GENERAL DISTRIBUTION.—Western United States south into Mexico. PGalapagos Islands.
GALAPAGOS DISTRIBUTION.—PMarchena.
Family GERRIDAE Amyot and Serville (Water Striders)
Nearly all water striders are adapted for and spend the active parts of their life cycles on the surface of fresh water, whether it be standing or running; the major exception are the ocean- going marine water striders of the genus Halo- bates. Considering the virtual absence of perma- nent bodies of fresh water on these tropical oceanic islands and the presence of oceans sur- rounding them, neither the absence of the fresh water forms nor the presence of the marine water striders is unexpected. These marine forms live chiefly on ocean surfaces away from the land, although they will enter coves and bays. They lay their eggs on floating objects, whether debris
or living creatures, such as birds sitting on the ocean's surface.
The four species known to occur on the ocean around the Galapagos Islands must have evolved on the oceans away from land and so the presence of each of them must be ascribed to a separate
"invasion"—a necessary minimum of four inva- sions.
The basic classification scheme of the Gerridae is that of Hungerford and Matsuda (1960) and of Matsuda (1960), with a significant modifica- tion by Andersen (1975). Because the family is represented within the archipelago only by its genus Halobates, the following two contributions are especially important: the taxonomic mono- graph of Halobates by Herring (1961), and Cheng and Shulenberger's (1980) detailed distribution information on four species of this genus in the eastern tropical Pacific Ocean.
Subfamily HALOBATINAE Bianchi Tribe HALOBATINI Bianchi Genus Halobates Eschscholtz
Halobates Eschscholtz, 1822:106 [type-species: Halobates mi- cans Eschscholtz, designated by Laporte, 1832:24].
DIAGNOSIS.—Wingless. Pronotum short, col- lar-like, set off posteriorly by a sharp transverse suture. Abdomen shorter than thorax. Color leaden gray, wholly sericeus.
REMARKS.—The Silberglied Collection con- tains two early instar nymphs taken on 23-25 March at Punta Espinosa, Fernandina (their spe- cific identity cannot be ascertained at this time).
Beebe (1924:84-89), in his observations on Halobates, reported that specimens accidently or experimentally wetted by immersion would sink and die. For nymphs at the Galapagos Islands he wrote: "when thoroughly soaked, three out of five failed to reright themselves and again float."
This is a surprising hazard for insects otherwise so evidently successfully adapted for life on the surface of the often turbulent ocean! In contrast, Cheng's (1973) study of the surface-fine struc-
ture of several species of water striders led her the Galapagos Islands. These include the three to deduce, without reference to Beebe's obser- open-ocean species, H. micans Eschsholtz, H. ser- vations, that these marine water striders have a iceus Eschscholtz, and H. sobrinus White, and the
surface cover sufficient to protect them from one island group species, H. robustus Barber. A wetting and drowning. These Halobates water fourth open-ocean species, H. splendens WxtXaczW, striders are generally grouped as one of two is now known to occur northward far enough to types: open-ocean forms that normally occur be found on the ocean in all directions from the away from land masses, sometimes hundreds of Galapagos Islands, as mapped by Chen and Schu- miles, but can be driven landward by storms on lenberger (1980:587). Because individuals of this the open ocean; or forms associated with islands latter species may be storm-tossed among the or island groups. Only four species have been islands or along their shores, the species is in- reported as actually occurring along shores of eluded in the key offered herein.
Key to Galapagos Species of Halobates
1. Apex of abdomen differentiated into a genital apparatus with a distinct angle on each side—males [all figures of genitalia, 33-38, in ventral view] 2 Apex of abdomen regularly angular, without a differentiated section—
females 6 2. Left subgenital styliform process much shorter than right one, at base abruptly bent out at right angle to body axis [Figure 33]. Length 4.5 mm 3 Left and right subgenital styliform processes subequal in length, neither bent at right angles to body axis 4 3. Right subgenital styliform process virtually straight [Figure 33]. Length 4.5 mm H. micans Eschscholtz Right syliform process strongly incurved [Figure 37]. Length 5 mm.
H. splendens Witlaczil 4. Left styliform process from near base, slightly bent outward [Figure 35],
right process straight, directed posteriad. Length 4.4 mm
H. sobrinus White Left and right styliform processes similarly developed, neither directed
outward [Figures 34 and 36] 5 5. Styliform processes about as long as genital capsule, their apices project- ing slightly behind outline of lateral angle of dorsal genital plate [Figure 34]. Length 3.6 mm H. sericeus Eschscholtz Styliform processes about two-thirds as long as subgenital capsule, their
apices not projecting [Figure 36]. Length 3.5 mm
H. robustus Barber 6. Meso- and metanota with abundant short, suberect, black bristles [best
seen from posterior view]. Length 4.2 mm
H. robustus Barber [Figure 21]
Meso- and metanota without bristles 7 7. Larger, length 5 mm. Anterior tarsus with its two segments about equal in length H. splendens Witlaczil
Smaller, length less than 4.5 mm. Anterior tarsus with first segment distinctly shorter than second 8 Antennal segment II very slightly longer than III, about half as long as IV. Length 3.4 mm H. sericeus Eschscholtz Antennal segment II one-third longer than III, about two-thirds as long
as IV. Length 4.0 mm 9 Middle and posterior femora, when projecting posteriad, with posterior femur reaching only three-fourths of way to apex of middle femur.
Length 4.0 mm H. micans Eschscholtz Middle and posterior femora, when arranged as above, with posterior femur reaching much more (eight-ninths) of way to apex of middle femur. Length 4.0 mm H. sobrinus White Halobates micans Eschscholtz
Halobates micans Eschscholtz, 1822:107 [South Atlantic Ocean (type)].—Barber, 1934:289 [Galapagos Islands];
1943:80 [Galapagos Islands].—Usinger, 1938:83 [Gala- pagos Islands]; 1951:321 [Galapagos Islands].—Herring, 1961:227, 246 [Galapagos Islands (small scale map record dot only)].—Linsley and Usinger, 1966:136 ["near" San Salvador].—Froeschner, 1981:37 [Galapagos Islands].
Halobates awuellerstorfi."—Uh\er, 1889:194 [San Cristobal].
Halobates "Wuellersdorffi."—He\demann, 1901:369 [San Sal- vador].
GENERAL DISTRIBUTION.—Atlantic Ocean be- tween 40° N and S latitudes; Indian Ocean;
Pacific Ocean between 20° N and 40° S lati- tudes.
GALAPAGOS DISTRIBUTION.—Nov. Near the islands of San Cristobal and San Salvador, but its very wide general distribution suggests it should occur on the oceanic waters between all the islands.
Halobates robustus Barber
Halobates "sp."—Heidemann, 1901:369 [Isabela].
'Halobates sp. nov."—Beebe, 1924:83, 432 [Santa Cruz];
1926:33 [Isabela].—Champion, 1924:260 [Galapagos Is- lands].
Halobates robustus Barber, 1925:253 [Galapagos Islands:
Santa Cruz (type)].—1934:289 [Santa Cruz, Santa Maria].
—Van Duzee 1937:118 [Santa Cruz].—Usinger, 1938:84 [Santa Cruz].—Herring, 1961:229, 282 [Galapagos Is- lands; (small scale map dot records only)].—Linsley and Usinger, 1966:136 [Isabela, Santa Cruz, Santa Maria].—
Cheng and Maxfield, 1980:43 [Isabela, Santa Cruz].—
Birch et a!., 1979:33 [Fernandina, Isabela, Santa Cruz, Santa Maria].—Froeschner, 1981:37 [Galapagos Islands].
SPECIMEN RECORDS.—San Cristobal*: coast 5 mi NE of Cerro Brujo, 14 Apr.
GENERAL DISTRIBUTION.—Galapagos Islands.
GALAPAGOS DISTRIBUTION.—Jan, Apr, Oct.
Fernandina, Isabela, San Cristobal*, Santa Cruz, Santa Maria.
Halobates sericeus Eschscholtz
Halobates sericeus Eschscholtz, 1822:108 [Pacific ocean "near the Equator" (type)].—Herring, 1961:227, 252 [Galapa- gos Islands (small scale map dot records only)].—
Froeschner, 1981:37 [Galapagos Islands].
GENERAL DISTRIBUTION.—Across the Pacific Ocean between 40° N an 40° S latitudes.
GALAPAGOS ISLANDS.—Reported from the oceans to the east and west of the Galapagos.
Halobates sobrinus White
Halobates sobrinus White, 1883:46 ["Taiti" in error! Known only from the Pacific Ocean along west coast of South America].—Herring, 1961:229, 251 [Galapagos Islands (small scale map dot record only)].—Linsley and Usinger, 1966:136 ["near Galapagos" Islands].—Froeschner, 1981:37 [Galapagos Islands].
GENERAL DISTRIBUTION.—Eastern Pacific Ocean between 30° N and 5° S latitudes.
GALAPAGOS DISTRIBUTION.—Galapagos Is-
lands.
Halobates splendens Witlaczil
Halobates splendens Witlaczil, 1886:178 [west coast of America between the Equator and the Tropic of Cancer
(type)].
REMARKS.—Not yet reported from the Gala- pagos Islands waters, but occurring on the open ocean in all directions from those islands, it may yet be blown close to shore.
GENERAL DISTRIBUTION.—Eastern tropical Pacific Ocean between 10° N and 20° S lati- tudes.
GALAPAGOS DISTRIBUTION.—Not yet reported (see comment above).
Family LYGAEIDAE Schilling (Lygaeid Bugs)
General life habits of members of the Lygaei- dae vary considerably. Some species, including some of the brightly colored ones, frequent ex- posed surfaces of plants; some are just as exposed but much less visible because their colors blend with their surroundings; still others hide in crev- ices or under objects; and some frequent ant tunnels. Their food habits also show considerable variation. Some feed on plant juices; others feed on plant seeds; some are predators on other insects; and one group prefers the blood of ver- tebrates. This array of foods includes some of man's crop plants and in some instances even his own blood. Some species have been reported to feed on dead animal bodies and on excrement, but these sources are probably incidental rather than a regular or essential parts of the diet of any of them.
One more genus and species, Tempyra biguttula Stal, are herein added to the nine species in eight genera listed by Ashlock (1972). Eight of the nine genera occur elsewhere on the American continents. The ninth one, Darwinysius, with two species, is restricted to these islands; Ashlock (1967:35) has placed it phylogenetically close to
several Neotropical genera. Of the ten species, two are recent introductions from the mainland, the other eight are restricted to the Galapagos Islands. These numbers suggest that evolution within the family on these islands is mostly at the specific level with very little at the generic level.
The two species of the genus Darwinysius are very close to each other and probably are sister species derived from a common ancestor that invaded the islands. Thus the conclusion can be reached that a minimum of nine invasions can be proposed to account for the ten species of Ly- gaeidae on the islands.
Literature significant for more technical study of the family Lygaeidae as it occurs in the Gala- pagos Islands includes the following: Ashlock's (1967) revision of the tribes and genera of the subfamily Orsillinae; his synopsis (1972) of the Lygaeidae known to occur on the Galapagos at that time, with keys and illustrations; Slater's (1964) catalogue; and Malipatil's( 1978) and Har- rington's (1980) revisions of the tribe Mydochini, which include modifications of the generic con- cepts in that group.
The Silberglied collection of Galapagos Ly- gaeidae contained one 5th instar nymph from Isla Pinzon (13-16 May 1970, R. Silberglied) for which I choose not to hazard a generic placement at this time. It is a stout individual measuring 4 mm in length and 2 mm across the abdomen. It has the head, pro- and mesonota longitudinally lineate with dark brown, and the abdomen red with numerous, crowded, small, yellow dots. The abdomen has two pairs of scent gland openings, between segments 4 and 5, and 5 and 6, and all the spiracles visible dorsally. The apex of its triangularly prolonged head surpasses the apex of the first antennal segment. It certainly is an Orsilline, but without associated adults I prefer to leave its exact placement to future studies.
Key to Galapagos Genera of Lygaeidae
Head behind the eyes prolonged and gradually narrowing posteriorly, forming a distinct neck; eyes separated from anterior margin of pronotum by a space greater than the horizontal diameter of an eye Heraeus Stal
