M. Chamberlain - SUBPHYLUM EURHODOPHYTINA

PART II: SUBPHYLUM EURHODOPHYTINA

Y. M. Chamberlain

FIGURE 52

Melobesia farinosa J. V. Lamouroux, 1816:315, pl. 12: fig. 3; Okamura, 1936:506; Hamel and Lemoine, 1953:102, fig. 64, pl. 21: figs. 1, 2;

Masaki and Tokida, 1960:39, pl. 1: figs. 4, 5, pl. 2: figs. 8–12, pls. 6, 7;

Adey and Lebednik, 1967:32; Chamberlain, 1983:343, fig. 19.

Hydrolithon farinosum (J. V. Lamouroux) D. Penrose et Y. M. Chamber- lain, 1993:295, figs. 2–19; Irvine and Chamberlain, 1994:123, figs.

3A, 54, 55; Riosmena- Rodríguez and Paul- Chávez, 1997:71; Yoshida, 1998:559; Rodríguez- Morales and Siqueiros- Beltrones, 1999:23;

L. Aguilar- Rosas et al., 2000:131; Riosmena- Rodríguez and Woelk- erling, 2000:339; CONANP, 2002:139; Fragoso and Rodríguez, 2002:119, figs. 20, 21; L. Aguilar- Rosas et al., 2002:234; Mateo- Cid et al., 2006:56; Serviere- Zaragoza et al., 2007:9; Y.- P. Lee, 2008:194, figs.

A–D; Mendoza- González et al., 2009:223, figs. 3, 4.

Fosliella farinosa (J. V. Lamouroux) M. Howe, 1920:587; Hamel and Lem- oine, 1953:102, fig. 64, pl. 21, figs. 1, 2; Dawson, 1960b:30, pl. 21: fig. 1, pl. 22: fig. 1; Masaki, 1968:21; Huerta- Múzquiz and Tirado- Lizárraga, 1970:128; Chávez- Barrear, 1972b:269; Huerta- Múzquiz and Garza- Barrientos, 1975:8, 11; Chamberlain, 1977:343; Coppejans, 1978:55;

Johansen, 1981:34: figs. 19A,B, 45: fig. 4A; Chamberlain, 1983:343, fig. 19 [lectotype]; Tseng, 1983:76, pl. 41: fig. 4; Stewart and Stewart, 1984:143; Mendoza- González and Mateo- Cid, 1986:423; Salcedo- Martínez et al., 1988:83; Ramírez and Santelices, 1991:205; Dreck- mann, 1991:34; León- Álvarez and González- González, 1993:461;

Serviere- Zaragoza et al., 1993a:483; Mendoza- González and Mateo- Cid, 1994:51; González- González et al., 1996:397.

Crusts epiphytic, very delicate, thin, of 2–3 cell layers, flat with a smooth surface; initially suborbicular, up to 4 mm broad,

up to 20 µm thick, crust margins rounded, lobed; later expand- ing, up to 1–2 cm (or more), often overlapping or overgrowing each other, up to 90 µm thick. Single basal layer of branched filaments with quadrangular cells, in surface view 15–30 µm long by 5.0–15 µm in diameter; cell fusions present. Epithallium a single layer of rounded cells. Trichocytes frequent throughout crust, often terminating a basal filament; single, 20–30 µm tall by 13–16 µm in diameter (Figure 52B).

Reproductive conceptacles uniporate; protruding above surface. Sporangial conceptacles 85–100 µm tall, 180–250 µm outside diameter; chamber 140–165 µm inside diameter; roof of 2–3 cell layers, about 15 µm thick; pore canal about 30 µm long and to 12 µm in diameter, lined with nonprotruding and more or less vertically oriented cells; tetrasporangia usually peripheral to central columella; zonately divided, (35–)70–80 µm tall, (20–)40–50 µm in diameter. Gametangial conceptacles smaller; monoecious;

carpogonia and spermatangia in separate conceptacles. Carpo- sporangial conceptacles chambers 40–105 µm tall, 75–205 µm inside diameter; conceptacle roof of 3–6 cell layers, 10–21 µm thick; gonimoblast filaments develop from fusion cell margins (peripheral surfaces); carposporangia 25–50 µm long, 24–40 µm in diameter. Spermatangial conceptacle chamber 11–40 µm tall, 45–75 µm inside diameter; conceptacle roof of 3 cell layers, roof pore about 6–12 µm in diameter, with mucilaginous spout extending to about 12 µm in length; spermatangial filaments pro- duced only from chamber floor (gametangia not known in Gulf;

after Mendoza- González et al., 2009, for Atlantic and Caribbean Mexico).

Habitat. Epiphytic on other algae, especially Padina, Dictyota, Dictyopteris, and Sargassum, and should be looked for

on sea grasses as well; mid intertidal to shallow subtidal, down to 5 m depths.

Distribution. Gulf of California: Punta Gorda (Gulfo de Santa Clara) to Isla Tiburón; Bahía de Loreto; Punta Palmilla to Cabeza Ballena; Isla María Cleofa (Islas Marías; Islas Tres Marías); Nayarit to Jalisco. Eastern Pacific: Isla Guadalupe;

Punta Santa Rosaliita (“Punta Santa Rosalía”) to Desembar- cadero de Miller (Miller’s Landing), Baja California; Isla Socorro (Islas Revillagigedo); Jalisco to Oaxaca; Chile. Western Pacific:

China; Vietnam; Japan; Korea.

Type Locality. “On Sargassum linifolium, Medi- terranean” (Chamberlain, 1994:123); “probably from Adriatic Sea” (Dawson, 1960b:30; Chamberlain, 1983:341).

Remarks. Hydrolithon farinosum is presumed to be a cosmopolitan species found growing on various benthic algae and sea grasses. In the northern Gulf, H. farinosum is often as- sociated with another epiphytic crustose coralline, Heteroderma gibbsii; both are sometimes found growing on species of Padina and Dictyota.

Melobesia farinosa J. V. Lamouroux (1816) is the type species of the generic name Fosliella M. Howe (1920). Studies by Penrose and Chamberlain (1993) determined that the type of

M. farinosa belonged to the genus Hydrolithon, thus making Fosliella M. Howe a heterotypic synonym of Hydrolithon.

Hydrolithon samoënse (Foslie) Keats et Y. M. Chamberlain Lithophyllum samoënse Foslie, 1906b:20; 1929:38, pl. 53: fig. 19 (lectotype);

Adey and Lebednik, 1967:17; Masaki, 1968:37, pl. 20: figs. 3, 4, pl. 23:

figs. 1–4, pl. 61: figs. 3–6, pl. 62: figs. 1–5; Guzmán del Próo et al., 1972:259; Mendoza- González and Mateo- Cid, 1985:30; 1986:423;

Ramírez and Santelices, 1991:212; Serviere- Zaragoza et al., 1993a:484;

Woelkerling, 1993:193; González- González et al., 1996:239; Woelker- ling, 1998:324; Woelkerling et al., 1998:493, fig. 205 (paratype).

Hydrolithon samoënse (Foslie) Keats et Y. M. Chamberlain, 1994:15, figs.

31–54; Chamberlain, 1994:126, figs. 56, 57; Yoshida, 1998:563;

Riosmena- Rodríguez and Woelkerling, 2000:344; Fragoso and Rodrí- guez, 2002:123, figs. 27, 28; Bittner et al., 2011:710.

Pseudolithophyllum samoënse (Foslie) W. H. Adey, 1970:13; Tseng, 1983:84, pl. 45: fig. 1.

Crusts pink, prostrate and spreading, with a relatively smooth surface (sometimes surface appearance somewhat ir- regular, resulting from uneven surface of substratum), 400–

800(–1100) µm thick; attached to rocks or mollusk shells. In vertical section: hypothallium of several layers of rectangular FIGURE 52. Hydrolithon farinosum: A. Surface view of decalcified crust showing prominent trichocytes (arrow). B. Surface view of decalcified crust showing cells of adjacent filaments conjoined by fusions and trichocytes at ends of filaments (JN-3169, US Alg. Coll.).

cells, (12–)15–20 µm tall and 5–7(–10) µm wide; perithallium forming largest portion of thallus, of small, squarish to rounded cells, 4–7 µm in diameter. Cell fusions frequent between cells in both hypothallial and perithallial filaments. Epithallium a single layer of rectangular cells, 2.5–4 µm tall and 4–7 µm wide.

Trichocytes occasional, terminal on erect (perithallial) filaments at thallus surface sometimes singular or forming short, loose horizontal rows (Fragoso and Rodríguez, 2002).

Sporangial conceptacles in crust surface, convex and slightly protruding, each with a single pore; in vertical section, ovoid, 93–102 µm in diameter, 37–66 µm tall; with zonately divided tetrasporangia. Conceptacle roof composed of an epithallial cell layer and an inner cell layer of tall thin elongated cells. Enlarged pore cells occur at base of conceptacle pore (Fragoso and Ro- dríguez, 2002). Spermatangial conceptacles in vertical section, 50–80 µm in diameter.

Habitat. On rocks and shells; mid to low intertidal.

Type Locality. Sataua, Savai’i Island, Samoa (for- merly Western Samoa).

Distribution. Gulf of California: Isla Pelícanos (Bahía Kino); Nayarit. Eastern Pacific: Isla Cedros (Baja Cali- fornia) to Bahía Tortugas, inside southeast Bahía San Bartolomé (Baja California Sur); Colima; Rapa Nui (Easter Island; Isla de Pascua). Western Pacific: China; Korea; Japan; Vietnam. Central Pacific: Samoa.

Remarks. Hydrolithon samoënse, recorded by Mendoza- González and Mateo- Cid (1986), is poorly known in the northern Gulf of California. Dawson (1960b, 1961b, as Lithophyllum samoënse) noted that his identification of this species from Isla Cedros (Pacific Mexico) was questionable and that more collections and critical comparisons were needed. A similar conclusion was made by Masaki (1968, as L. samoënse) who observed Japanese specimens were twice as thick as those of Dawson (1960b), and Keats and Chamberlain (1994) also suggested some of the specimens may not be this species. In their de- scription of Hydrolithon samoënse from tropical Pacific Mexico, Fragoso and Rodríguez (2002) also noted that Dawson’s (1960b) specimens need to be reexamined. In another study, Bittner et al.

(2011) suggested H. samoënse belongs in the genus Porolithon,

but Kato et al. (2011) noted that its relationship to Porolithon was unresolved. All Gulf of California specimens identified as H. samoënse should be critically compared with type material.

corallinaceaeSuBfam. maStophoroideae

Corallinaceae subfam. Mastophoroideae Setchell, 1943:134 [as “Masto- phoreae”]; Woelkerling, 1996c:237.

Members include crustose corallines that are prostrate to partially erect and may be discoid or spreading with more or less smooth to warty surfaces, or with short unbranched to branched protuberances. They grow on rocks or other hard substratum, some are free- living rhodoliths, and a few are reported to be endophytic. Thalli are dimerous (first- order filaments making a single layer and second- order filaments arising at right angle from the dorsal side of first- order filaments) or monomerous (single order of filaments) in construction or both. Some cells of adjacent filaments linked by cell fusions. Secondary pit connections are absent in most, or rare (known in one genus, Metamas- tophora Setchell, 1943). Sporangial conceptacles are uniporate, tetrasporangia and bisporangia are without apical plugs. Gam- etangial thalli, where known, are monoecious or dioecious. Car- pogonial and spermatangial conceptacles are uniporate.

Remarks. Gene sequence analyses of Bailey et al.

(2004) revealed C. subfam. Mastophoroideae to be polyphy- lectic, belonging to four distinct lineages. Kato et al. (2011) restricted the subfamily to include only Mastophora Decaisne (1842a; see Keats et al., 2009:417, for summary of genus charac- ters) and Metamastophora Setchell (neither of which have been found in the Gulf of California), and left the placement of Spong- ites and Pneophyllum unresolved until their generitypes could be studied. Until the needed studies are completed, for convenience the other genera are treated in C. subfam. Mastophoroideae (fol- lowing Woelkerling, 1996c). Much work remains to clarify the molecular systematics and phylogenetic relationships of the genera and species of Pneophyllum, Spongites, and Heteroderma, as well as the generic placement of one species of “Fosliella.”

The five genera reported in the northern Gulf of California are provisionally retained in the C. subfam. Mastophoroideae.

KEY TO THE GENERA IN C. SUBFAM. HYDROLITHOIDEAE AND THOSE TENTATIVELY IN C. SUBFAM. MASTOPHOROIDEAE IN THE NORTHERN GULF OF CALIFORNIA

1a. Crusts thin, usually less than 200 µm thick, without protuberances; often epiphytic, not forming free- living rhodoliths . . . 3 1b. Crusts thicker, generally greater than 200 µm thick, may have protuberances; on rocks, epiphytic, or may form free- living rhodoliths . . . 2 2a. Sporangial conceptacle pore canal in vertical section lined with cells parallel to roof that protrude into pore canal; thallus

construction either monomerous or dimerous, although in some may be both; trichocytes not observed in primigenous (first order; basal) filaments . . . Spongites 2b. Sporangial conceptacle pore canal in vertical section lined with cells perpendicular to roof surface that do not protrude

into pore canal; thallus construction primarily dimerous (can be monomerous and radially arranged in protuberances);

trichocytes terminal on primigenous filaments . . . Hydrolithon (in part) 3a. Trichocytes absent . . . Heteroderma 3b. Trichocytes present or absent . . . 4

4a. Trichocytes when present, intercalary within primigenous filaments or terminal on postigenous (second order; erect) filaments; pore canal of sporangial conceptacles (in vertical section) lined, at least initially, by horizontally oriented cells (parallel to conceptacle roof surface); germination disc with 8- celled center . . . . Pneophyllum 4b. Trichocytes when present, terminal on primigenous filaments or intercalary on postigenous filaments; pore canal of spo-

rangial conceptacles (in vertical section) lined by enlarged vertically oriented cells (perpendicular to conceptacle roof);

germination disc with 4- celled center . . . 5 5a. Thalli not extensively overlapping each other; sporangial conceptacles 200–225 µm in diameter . . . “Fosliella?” paschalis 5b. Thalli often overlapping each other; sporangial conceptacles smaller, 100–160 µm in diameter . . . . Hydrolithon (in part)

Heteroderma Foslie

Heteroderma Foslie, 1909:56.

Crustose corallines are thin, 2–5 cells layers thick, and found growing as epiphytes on other macroalgae. Thallus construction is dimerous, composed of basal, first- order (primigenous) filaments, and second- order (postigenous) filaments. Trichocytes and secondary pit connections are absent. Intercellular fusions are present.

Sporangial and gametangial conceptacles open by a single pore. In some species a gelatinous spout extends outward from pore of the spermatangial conceptacles.

Remarks. Heteroderma is tentatively recognized until the genus can be further clarified. The use of a single di- agnostic character—the absence of trichocytes in Heteroderma versus their presence in Hydrolithon—for their generic separation has been questioned by some. It has been suggested that presence or absence of trichocytes may reflect an environmental

response. Others, however, contend that trichocytes represent a fundamental phylogenetic difference between these groups (e.g., Masaki, 1968:56). In recognizing Heteroderma as a genus, Fos- lie (1909) did not designate a type species (generitype). Setchell and Mason (1943b) later chose H. subtilissimum (Foslie) Foslie (1909; basionym: Melobesia subtilissima Foslie, in Weber- van Bosse and Foslie, 1904) to lectotypify the genus. Chamberlain (1983) examined the type collection of H. subtilissimum (Foslie) Foslie and considered it to be a minute Pneophyllum Kützing (1843) but did not transfer the species (Woelkerling, 1988).

For now, the species from the Gulf of California are tentatively referred to Heteroderma until their generic status and phylogenetic relationships can be further elucidated, including genetic comparisons to the type from the reef at Atjatuning, off the west coast of New Guinea.

Three species of Heteroderma, including two described from the Gulf of California, are known to occur in the northern Gulf.

KEY TO THE SPECIES OF HETERODERMA IN THE NORTHERN GULF OF CALIFORNIA

1a. Crusts mostly a single cell layer; very thin, 7–10 µm thick; sporangial and carpogonial conceptacles small, 70–100 µm outside diameter; spermatangial conceptacles conical, small, base 45 µm in diameter, upward narrowed to 25–28 µm in diameter, pore often with extending gelatinous spout . . . H. subtilissimum 1b. Crusts initially only 1 cell layer, later developing more cell layers; thicker, 10–50 µm thick; sporangial and carpogonial conceptacles slightly larger (mostly more than 90 µm outside diameter); spermatangial conceptacles not conical, pore without extending gelatinous spout . . . 2 2a. Crusts 25–50 µm thick, of 2–4 vegetative cell layers; reproductive portions of 10–12 cell layers and up to 100 µm thick;

sporangial conceptacles up to 200 µm outside diameter, chamber about 100 µm inside diameter,70 µm tall; carposporangial conceptacle chambers 90 µm inside diameter, 80 µm tall . . . H. corallinicola 2b. Crusts mostly thinner, 10–30 µm thick, of 1–2 vegetative cell layers, reproductive and older portions of 3–5 cell layers;

sporangial conceptacles larger, 250–300 µm outside diameter, chamber 210 µm inside diameter, 105 µm tall; carposporangial conceptacles larger, 225–275 µm outside diameter, chambers 140–200 µm inside diameter . . . H. gibbsii

Heteroderma corallinicola E. Y. Dawson

FIGURE 45B

Heteroderma corallinicola E. Y. Dawson, 1944a:273, pl. 63: fig. 2; 1960b:

53, pl. 48: fig. 2; 1961b:417; González- González et al., 1996:224;

Riosmena- Rodríguez and Woelkerling, 2000:327.

Crusts epiphytic, minute, closely adherent on surfaces of host; monostromatic only in marginal portions; centrally, 25–50 µm thick, usually of 2–4 layers of quadrangular cells, 9–14 µm in diameter; reproductive portions up to 100 µm thick, up to 10–12 cell layers. Hypothallium of slightly horizontally broad- ened cells, up to 14 µm wide. Perithallium layers of squarish to slightly vertically elongated cells. Trichocytes absent.

Sporangial conceptacles dome shaped, up to 200 µm outside diameter; chamber about 100 µm inside diameter and 70–90 µm tall, with concave floor of 2 or more cell layers; tetrasporangia faintly divided or appearing undivided (possibly immature), up to 70 µm long, 30 µm in diameter. Carposporangial conceptacles more or less hemispherical; chambers about 90 µm in diameter, about 80–90 µm tall, with concave floor of 3 or more cell layers.

Spermatangial conceptacles prominent, chamber 50–60 µm inside diameter, 40–50 µm tall, with a flat to slightly concave floor.

Habitat. Epiphytic on Corallina on rocks and in tide pools; mid to low intertidal.

Distribution. Gulf of California: Guaymas.

Type Locality. On Corallina in tide pools; cove north of Cabo Arco, Guaymas, Sonora, Gulf of California, Mexico.

Remarks. Dawson (1960b) commented the Gulf endemic Heteroderma corallinicola grows on Corallina, has tetrasporangia, and is morphologically very similar to the western Atlantic H. chamaedoris (Foslie et M. Howe) E. Y. Daw- son (1960b; basionym: Lithophyllum chamaedoris Foslie et M. Howe, 1906). Heteroderma chamaedoris, described from the Bahama Islands, is epiphytic on the green alga Chamaedoris peniculum (J. Ellis et Solander) Kuntze (1898) and has bisporangia. Apparently the type of sporangia, different algal hosts, and geographical separation are the primary differences between these two species.

Heteroderma gibbsii (Setchell et Foslie) Foslie

FIGURES 53, 54

Melobesia gibbsii Setchell et Foslie in Foslie 1907:26; Woelkerling 1993:106.

Heteroderma gibbsii (Setchell et Foslie) Foslie, 1909:56; Dawson, 1944a:272;

1959a:20; 1960b:54, pl. 21: figs. 4–6, pl. 23: fig. 2; 1961b:417;

1966a:19; Adey 1970:16; González- González et al., 1996:224;

Riosmena- Rodríguez and Paul- Chávez, 1997:71; Riosmena- Rodríguez and Woelkerling, 2000:339; CONANP, 2002:139; Pacheco- Ruíz and Zertuche- González, 2002:467; Pacheco- Ruíz et al., 2008:208.

Coralline crusts, initially suborbicular in surface view, with lobed margins; basically monostromatic in young crusts and margins, thin, up to 30 µm thick; later becoming irregu- lar in outline and increasing to 3–4 cell layers in reproductive and older portions; epiphytic on various brown and red algae;

numerous individuals can cover extensive portions of host alga, usually with little overlap of one another. Hypothallium parallel to substratum, a single layer of filaments of horizontal elongated

cells (11–16 µm long, 6–12 µm wide). Perithallium of 2–4 cell layers of squarish cells (about 7–12 µm in diameter); the upper- most layer of vertically elongated cells, 11–16 µm long, 6–12 µm in diameter. Epithallium irregularly developed, a single layer of small cells 2–4 µm high and 6–10 µm wide. Trichocytes absent.

Sporangial conceptacles dome- shaped above crust surface, 250–300 µm outside diameter; chamber 210 µm inside diameter and 105 µm tall, with floor of 1–2 cell layers; zonate tetrasporangia about 50 µm long. Carposporangial conceptacles 225–275 µm outside diameter; chambers 140–160(–200) µm inside diameter, 40–70 µm tall, with floor of 1–2 cell layers. Spermatangial conceptacles only slightly prominent; chambers 40–50 µm inside diameter, (12–) 16–30 µm tall.

Habitat. Epiphytic on various red and brown algae, including Dictyota, Padina, Sargassum, Gracilaria, and Lauren- cia; often found growing along with other epiphytic species of crustose corallines on same host; intertidal (although probably restricted to the intertidal zone, it has also been dredged from 40 m depth; Dawson, 1944a).

Distribution. Gulf of California: Puerto Peñasco to Guaymas; Puerto Refugio, Isla Angel de la Guarda and Isla Turner (Islas de la Cintura); Isla San José to San José del Cabo.

Syntype Localities. Epiphytic on Sargassum: Isla San José (25º00’N; 110º38’W), and Isla Espíritu Santo (east of Bahía de La Paz: 24º30’N; 110º22’W), Baja California Sur, Gulf of California, Mexico.

Remarks. Dawson (1960b) observed that Gulf of California endemic Heteroderma gibbsii could resemble some Pneophyllum nicholsii. The most apparent differences are that H. gibbsii has larger sporangial conceptacles and smaller spermatangial conceptacles than those of P. nicholsii. Dawson (1960b) suggested the La Paz specimen identified by Mason (1953) as “H. nicholsii” [non H. nicholsii Setchell et L. Mason, 1943b; now P. nicholsii (Setchell et L.R. Mason) P. C. Silva et P. W. Gabrielson, in Gabrielson et al., 2004] was in all probabil- ity also H. gibbsii.

Heteroderma subtilissimum (Foslie) Foslie

FIGURE 55

Melobesia subtilissima Foslie in Weber- van Bosse and Foslie, 1904:55; Foslie, 1905b:8; Chamberlain, 1983:312; Woelkerling, 1993:218.

Heteroderma substilissimum (Foslie) Foslie, 1909:56; Dawson, 1956:48, fig. 41; 1960b:58, pl. 49: figs. 5, 6; 1961b:417; 1966a:20; Adey, 1970:17; Stewart and Stewart, 1984:143; Dreckmann 1991:34, as

“Pneophyllum subtilissima”; González- González et al., 1996:225;

Riosmena- Rodríguez and Woelkerling, 2000:345; Fernández- García et al., 2011:62.

Crusts minute, epiphytic on various algae; initially more or less discoid, later forming lobed crusts up to 2 mm wide, very thin, 7–9 µm thick. Vegetative portion of crust essentially monostromatic; in vertical section, quadrangular cells squarish to rounded to slightly horizontally elongated, 7–12 µm in diameter; cells in surface view 11–17 µm long, 7–12 µm wide, arranged in radiating rows. Crust thicker near conceptacles.

FIGURE 53. Heteroderma gibbsii: Habit of irregularly shaped crust epiphytic on Padina, mostly monostromatic, except for conceptacles (EYD-457, AHFH, now UC).

Erect filaments (perithallial and epithallial cells) mostly absent.

Trichocytes absent.

Sporangial conceptacles dome- shaped, 70–100 µm in outside diameter; chamber 45–60 µm in diameter, with flat floor of one cell layer; tetrasporangia zonate, about 25 µm tall, 14–17 µm in diameter. Carposporangial conceptacles also dome- shaped, 60–90 µm in outside diameter, nonrostrate to slightly rostrate.

Spermatangial conceptacles small, conical, about 45 µm wide at base, narrowing upward to 25–28 µm in diameter; ostiolate with a gelatinous spout, up to 25 µm long (after Dawson 1960b).

Habitat. Epiphytic on Cladophoropsis, Halimeda, leaf- like blades of Sargassum, Jania, and probably other algae as well; intertidal to shallow subtidal.

Distribution. Gulf of California: Punta Pelícano, Puerto Peñasco; Bahía San Gabriél, Isla Espíritu Santo to Cabo Pulmo. Eastern Pacific: Isla Guadalupe (off Baja California); El Salvador.

type Locality. Epiphytic on Corallina pilifera; reef off Atjatuning, west coast of New Guinea (Dawson, 1960b; Ver- heij and Woelkerling, 1992).

Remarks. The taxonomic status of Gulf of Califor- nia specimens referred to H. subtilissima is in need of further elucidation (see also Remarks for Heteroderma).

Fosliella M. Howe

Fosliella M. Howe, 1920:587.

Algae are thin, calcified crusts, usually less than 200 µm thick, and epiphytic and firmly adherent on various macroalgae and seagrasses. Internally (as seen in vertical section), they are dorsiventrally organized and dimerous, composed of two types of filaments. Primigenous (first order) filaments form a single layer growing parallel (horizontal) on the host; and postigenous (second order) filaments grow more or less upward (vertical).

Erect filaments may sometimes consist of only a single epithallial cell. Cells in adjacent filaments are sometimes joined by cell fusions, secondary pit connections are unknown. Trichocytes are sometimes present as terminal cells of the first- order filaments or intercalary in second- order filaments.

Tetrasporangia and sometimes bisporangia are developed within uniporate conceptacles, without apical sporangial plugs.

Each spore germinates into a characteristic 4- celled sporeling, FIGURE 54. Heteroderma gibbsii: A. Transection through algal host and decalcified crust with tetrasporangial conceptacle (JN & HWJ- 73-7-22c, US Alg. Coll.). B. Transection through algal host and decalcified crust with tetrasporangial conceptacle (JN & HWJ-73-7-15, US Alg. Coll.).

FIGURE 55. Heteroderma subtilissimum: A. Transection through mature tetrasporangial conceptacle. B. Surface view of portion of crust (A, B, after Dawson, 1960a: pl. 49: figs. 5,6).

Dalam dokumen Marine Algae of the Northern Gulf of California II: Rhodophyta (Halaman 134-200)