Shallow-Water Gorgonians (Octocorallia) of Roatan, Honduras

BULLETIN OF MARINE SCIENCE, 50(1): 212-226. ]992 CORAL REEF PAPER

SHALLOW -WATER GORGONIANS (OCTOCORALLIA) OF ROATAN, HONDURAS

Donald E. Keith

ABSTRACT Twenty-three species of gorgonians were collected from coral reefs along the southern shores of Roatan during March 1979. Included are 13 plexaurids, counting two growth forms of Plexaura homomalla and Eunicea tourneforti, eight gorgoniids, one ellisellid, and one scler- axonian. Reef habitats included back-reef rubble zones and flats, patch reefs, and a fore-reef slope. Collections were made using SCUBA from depths of I to 25 m. Identifications were based on examination of spicule structure and colony morphology. This paper provides information for recognizing Roatan species and includes several which have developed locally- adapted populations that differ in colonial structure from holotypes described by Bayer (1961). Two species collected at Roatan, Pseudopterogorgia hummelincki and Ellisella elongata, have not previously been reported from the Caribbean coast of Central America. Colony structure, spiculation, habitat and geographic distribution are considered. A table summarizes the distribution of shallow-water gorgonians along the Caribbean coast of Central America.

Previous investigations of octocorals in the West Indies are numerous. Pertinent studies include those of Hargitt and Rogers (1901); Verrill (1912); Gordon (1925); Hickson (1930); Deichmann (1936); Bayer (1958; 1961; 1981); Gonzalez-Brito (1970; 1972); Goldberg (1973); Kinzie (1973); Opresko (1973); Rees (1973); Pres- ton and Preston (1975); Cairns (1977); Botero (1987); and Wheaton (1987). Published accounts of octo coral from the Caribbean coast of Central America are few when compared to other parts of the Caribbean. The most extensive investigations have been conducted at Yucatan and Belize. Community structure and zonation of gorgonians along the northeastern part of the Yucatan Peninsula have been investigated by Jordan (1979) and Dahlgren (1989). Numerous studies have been conducted on the Atlantic barrier reef ecosystem at Carrie Bow Cay, Belize. Community structure was investigated by Burke (1982), and octocora1 distribution and abundance of common species were studied by Muzik (1982). Lasker and Coffroth (1983) provide information on zonation and abundance for 36 gorgonians at Belize. Kocurko (1987) collected 19 species from shallow-water environments around San Andres Island, Colombia, located about 200 km east of Nicaragua. Bayer (1961) identified nine species from collections made at La Providencia, approximately 80 km north of San Andres Island. Guzman and Cortes (1985) surveyed shallow-water octocorals along the Caribbean coast of Costa Rica, and Tortora and Keith (1980) listed 12 species from the Swan Islands, located about 160 km northeast of Honduras. There are no published accounts of gorgonians from any of the Honduran Bay Islands. Roatan is the largest of the Bay Islands and is located about 50 km north of mainland Honduras (Fig. 1). This island is approximately 30 km long with a maximum width of 4 km. An account of the geology is given by McBriney and Bass (1969), and geographical information is provided by Davidson (1974). Studies were conducted in coral reefs along the southern shores ofRoatan during March 1979. Twenty-three species of gorgonians, including two growth forms, were collected. This paper provides a means of recognizing Roatan gorgonians including several which have developed locally-adapted populations that differ in colonial structure from holotypes described by Bayer (1961). This study also

212 KEITH: GORGONIANS OF ROATAN 213

UNITED STATES

Atlantic Ocean

Gulf of Mexico

SWAN IS. e. -" ~ ~ CJ' ROAr AN \. HAITI ~ I •• .-' Caribbean Sea

VENEZUELA

Figure I. Map of Caribbean showing location of Roatan. provides important information about gorgonian distribution along the Caribbean coast of Central America. Distinguishing features are given for each species to aid in their identification and are not intended to be detailed species descriptions. The reader is referred to Bayer (1961) for more specific taxonomic information and photographic plates of the coral colonies.

METHODS

Gorgonians were collected from shallow-water reef habitats along southern Roatan shores from Caribe Point, also known as Carter's Point, to Allen's Point. Collecting efforts were concentrated in reefs at Caribe Point, Oak Ridge, and Horseshoe Reef. These sites were selected because of their accessibility and range of habitat types. Horseshoe Reefis a patch reef about 1.5 km in length located off Jenning's Point between Lime Cay and Fort Cay. Sand flats and a shallow back-reef rubble zone occur at Caribe Point. At Oak Ridge there is a very shallow back-reef rubble zone followed by a gradual increase in depth to about 10-15 m. At this point there is an abrupt change in slope with the fore reef plunging in an almost vertical reef face. The slope was studied to depths of 25 m. Collections were made by using SCUBA which allowed for selective removal of colonies. Efforts were made to collect as many different species as possible but the probability of missing closely related forms is always high when selective collecting methods are employed. This method was used so as to have the least impact On the coral community. Some material was preserved in 10% neutralized formalin but most colonies were air dried. 214 BULLETIN OF MARINE SCIENCE, VOL. 50, NO. I, 1992

Specific identification of coral colonies involved gross colony morphology and identification of type and arrangement of spicules in the cortical layers and axial sheath. Spicule preparations were made by dissolving fragments from various layers of coenenchyme in small vials of sodium hypochlorite. This procedure was followed by rinsing the sderites with distilled water and storing them in 70% ethano1. Permanent slides were made by transferring the spicules to a glass slide and allowing the alcohol to evaporate, then setting in Permount. Drawings were made by tracing the slide-mounted spicules using a micro projector. Anthocodial spicule arrangement was determined by submerging the anthocodium in a dilute so- lution of sodium hypochlorite and observing it under a stereoscopic microscope. The spicular arrangement is revealed as the tissues swell and become transparent.

SYSTEMATIC ACCOUNT

Order Gorgonacea Suborder Scleraxonia Family Briareidae

Briareum asbestinum (Pallas, 1766) Four species of Scleraxonia are common to West Indian reefs and three are distributed along the Caribbean coast of Central America. Briareum asbestinum was the only species collected at Roatan. This species consists of unbranched colonies originating from a single basal expansion. The colony may be erect, lobate, club-like, or encrusting. The medulla is spicular, but there is no axial core of calcified or horny material. The most common form consisted of erect branches with long polyps giving the colony a furry brown or sponge-like appearance. Dry specimens have a purple tint and an asbestos-like texture. Spicules consist oflarge tuberculate spindles up to 1 mm in length, and triradiate bodies (Fig. 2A). Those of the cortex and medulla are similar except medullar spicules are larger and contain purple as well as white forms. This is a very common species ranging throughout the Caribbean. It often dominates in patch reefs (Lasker and Coffroth, 1983) and typically ranges from shallow water to 20 m, but has been reported by Wheaton (1987) to be common at 35 m. The species was abundant at Roatan, particularly in patch-reef habitats such as Horseshoe Reef.

Suborder Holaxonia Family Plexauridae

The holaxonian axis is not composed of spicules, or if so, it has a distinct chambered core. Families of holaxonians at Roatan include Plexauridae, Gor- goniidae, and Ellisellidae. Plexauridae have a chambered core, retractile anthocodiae, and large spicules which are irregularly sculptured. Spicules of the outer cortex consist of clubs, or butterfly-shaped quadriradiates if clubs are absent. Thirteen plexaurids were collected including two forms of Plexaura homomalla and Eunicea tourneJorti.

Plexaura homomalla (Esper, 1792) forma homomalla

The colony is bushy, flattened and dichotomously branched. The surface is granular and calyces have raised rims and large openings. Dried specimens are usually dark brown to almost black in color. KEITH: GORGONIANS OF ROATAN 215

~l,Wj .lmm

.5mm

Figure 2. Gorgonian spicules. A. Tuberculate spindle and triradiate body of Briareum asbestinum. B. Asymmetrical leaf clubs and unilaterally foliate body from outer cortex of Plexaura homomalla. C. Capstan and stellate bodies from axial sheath of P. homomalla. D. Leaf clubs from surface layer of Plexaura jlexuosa. E. Stout spindle from middle layer of P. jlexuosa. F. Spicules from outer cortex of Pseudoplexaura porosa. G. Branched spindle from middle layer of P. porosa. H. Spicules from outer cortex of Pseudoplexaura jlagellosa. I. Multiradiate capstans from axial sheath of P. jlagellosa. J. Cortical clubs of Pseudoplexaura wagenaari showing spheroidal heads. K. Torches from outer cortex of Eunicea mammosa. L. Large spindle from middle layer of E. mammosa. M. Leaf clubs from outer cortex of Eunicea tourneforti. N. Large spindle from middle layer of E. tourneforti. 216 BULLETIN OF MARINE SCIENCE, VOL. 50, NO. I, 1992

Characteristic spicules in the outer cortex include large asymmetrical leaf-clubs and unilaterally foliate bodies up to about 0.5 mm in length (Fig. 2B). The middle layer has white to colorless spindles up to 0.8 mm long, and a few lavender spindles may also be present. The axial sheath contains reddish purple capstans (0.14-0.2 mm) and stellate forms of approximately the same size, but there are no branched forms (Fig. 2C). The species is common and widespread throughout the Caribbean from depths of 0-30 m. It was found in Roatan reefs to the deepest depths collected, but was most abundant at shallow to moderate depths in patch reefs and the fore-reef slope.

Plexaura homomalla (Esper, 1792) forma kukenthali Moser, 1921 Colonies resemble the typical form except they are taller, bushier, and the branches are more slender, measuring about 2.5 cm at their terminals. The calycular rim is lower giving the colony a smoother texture. Large leaf-clubs and unilaterally foliate bodies are present but reduced in size. Clubs reach lengths of about 0.35 mm. Spindles ofthe middle layer are more curved than in the typical form. This form was not as common as the typical P. homomalla. It was collected from a patch reef at an estimated depth of 12 m, but has been reported to depths of 53 m (Kinzie, 1973). Lasker and Coffroth (1983) found this form to be most abundant in the fore-reef ridge at Belize.

Plexaura j/exuosa (Lamouroux, 1821) This species resembles P. homomalla because of similarities in colony shape; however, the texture of P.j/exuosa is more firm in living and preserved specimens and the colony is lighter in color, ranging from pale yellow through light to medium brown, to purple or reddish purple. The calycular apertures commonly have an inconspicuous lower lip, particularly near the branch tips. Colonies vary as to the degree of calycular elevation. Spicules of the surface layer include large leaf-clubs about 0.2 mm in length, often with 3-4 serrated folia (Fig. 2D). This is the most reliable feature for distinguishing this species. Middle layers contain stout spindles up to 2 mm in length and 4-6 times longer than wide (Fig. 2E). The axial sheath possesses deep reddish purple capstans, stellate bodies, short belted rods and short spinose spindles. This was an extremely common species, and was collected from the fore-reef slope at Oak Ridge and from Horseshoe Reef at depths of 5-10 m. It has been reported by Kinzie (1973) to depths of 47 m.

Pseudoplexaura porosa (Houttuyn, 1772) This genus is characterized by pore-like openings and no projecting calyces. The axial sheath has deep reddish-purple capstans, spindles, and branched bodies. P. po rosa is a large bushy colony with round, tapered branches to 4 mm thick. It is distinguished by widely gaping calycular apertures separated by less than their own diameter. Dried colonies appear light tan to buff in color. The outer cortex contains many colorless, tuberculate spindles reaching lengths of 1 mm, and clubs up to 0.45 mm that may grade into unilaterally spinose bodies. (Fig. 2F). The middle layer has purple spindles which may be branched with 3- 4 rays (Fig. 2G). The axial sheath is composed of reddish-purple capstans, small spindles and irregular branched spicule types. KEITH: GORGONIANS OF ROATAN 217

This is a common gorgonian, ranging from Bermuda, southern Florida and throughout the Caribbean. Colonies were collected from the fore reefat Oak Ridge at a depth of about 10 m. It typically ranges from 0-30 m, but has been reported to depths of283 m off Colombia by Bayer (1961).

Pseudoplexaura flagellosa (Houttuyn, 1772) Colonies are moderately large and dichotomously branched more or less in one plane. They superficially resemble P. porosa but their pore-like apertures are separated from each other by distances equal to or greater than their own diameter. The outer layer contains small, slender spindles, many of which are bent, and small leaf-clubs (Fig. 2H). Small purple, multiradiate capstans are present in the axial sheath (Fig. 21). This common species ranges from Bermuda and throughout the Caribbean. Specimens were collected from the fore reef at Oak Ridge at about 15 m. It is reported to depths of 50 m.

Pseudoplexaura wagenaari (Stiasny, 1941) Colonies are small and dichotomously branched. Apertures are small and separated by more than their own diameters. The species can be distinguished from P. flagellosa by the smaller colony size, fewer number of branches, and differences in the outer cortical clubs. The cortical clubs of P. wagenaari have spheroidal heads (Fig. 2J); whereas, those of P. flagellosa may have rounded folia but they are never spheroidal. The axial sheath contains purple capstans and branched spindles. This species has been reported from Bermuda, Florida and throughout the Antilles to Venezuela. It was found at Belize by Muzik (1982) and at the Swan Islands by Tortora and Keith (1980). Specimens were collected at Oak Ridge from the fore-reef slope at a depth of about 15 m, but the species is reported to depths of 30 m.

Eunicea (Eunicea) mammosa Lamouroux, 1816 Eunicea colonies are bushy or candelabrum-shaped with round branches and projecting calyces that often stand out prominently from the surface. The genus is characterized by the predominance of spindle- or rod-shaped sclerites in the axial sheath and an abundance of clubs in the outer cortex. Eunicea mammosa colonies are relatively smalI and tend to spread in one plane with lateral and dichotomous branching. The species is distinguished by its rounded, upturned calyces which are typically close-set and low but may be up to 5 mm in length. The length of calycular projections and diameter of the branches vary according to the habitat. Dried colonies are usually tan to medium brown in color. The outer cortex contains clubs in the shape of torches which range up to 0.2 mm in length (Fig. 2K). The middle layer contains large stout tuberculate spindles up to 1.9 mm long and 5-8 times longer than wide. They may be white, colorless or purple (Fig. 2L). The axial sheath contains acute purple tuberculate and spinose spindles 0.1-1.3 mm in length. This is a common Caribbean species. It was collected at Caribe Point from moderate depths of 4-1 a m, and from Horseshoe Reef at approximately 8 m. It has been reported to depths of 25 m. Kinzie (1973) found it characteristic of the rear zone of a Jamaican reef, and Muzik (1982) collected it from the outer reef ridge at Carrie Bow Cay, Belize. 218 BULLETIN OF MARINE SCIENCE. VOL. 50. NO. I, 1992

.1mm

I I .05mm

.3mm

I .05mm .05mm

.05mm

I I .05mm .05mm Figure 3. Gorgonian spicules. A. Giant spindle from middle layer of Eunicea calyculata forma coronata. B. Torches from outer layer of E. calyculata C. Unilaterally spinose spicules of outer cortex of Muriceopsis j/avida. D. Quadriradiate and triradiate spicules from outer cortex of Plexaurella dichotoma. E. Spindles with tubercles and simple spines from the outer cortex of Muricea muricata. F. Cortical scaphoids of Pseudopterogorgia bipinnata. G. Cortical scaphoids of Pseudopterogorgia KEITH: GORGONIANS OF ROATAN 219

E unicea tourneforti Milne Edwards and Haime, 1857 forma tourneforti Colonies are stout, candelabrum-shaped and often dark gray to black. Calyces are prominent, upturned and have a projecting lower lip. This species is very common and is sympatric with E. mammosa. The outer cortex contains wart- and leaf-clubs 0.1-0.15 mm in length, but no torches (Fig. 2M). Spicules of the middle layer are large, white spindles up to 1.6 mm in length and 0.4 mm wide (Fig. 2N). The axial sheath contains blunt tu- bercular rods (0.3-0.5 mm) and short capstans (0.16 mm) which are clear or lavender in color. This was one of the more common gorgonians at Roatan. It was collected at Horseshoe Reef, Caribe Point and Oak Ridge on shallow slopes of the fore reef at moderate depths. The species is widespread from Bermuda and throughout the Caribbean to depths of 15 m.

Eunicea tourneforti Milne Edwards and Haime, 1857 forma atra Verrill, 1901 Colonies are similar to the typical form but are distinguished by looser branching and smaller branch diameters (6-10 mm). Spiculation is also similar except that the large spindles are sometimes stouter.

Eunicea calyculata (Ellis and Solander, 1786) forma coronata Bayer, 1961 Colonies are bushy and dichotomously branched. Margins of the calycular apertures project throughout most of the colony. E. calyculata coronata differs from the typical form by having lower colonies (15-20 em), and smaller, more slender branches with diameters of about 4 mm opposed to 8-16 mm in the typical form. Calyces extend about 2.5 mm and are without an upturned lower lip. Dried colonies are gray to light brown in color. The middle layer consists mostly of large white spindles ranging from 0.18 mm to giant spindles of 2.4 mm (Fig. 3A); most average about 1.5 mm. The large spindles are somewhat longer and more curved than in the typical form. The outer rind contains small wart- and leaf-clubs 0.06-0.16 mm in length (Fig. 3B). The axial sheath near the base contains mostly purple spinose rods and spindles 0.2-0.4 mm long. There are stout purple spindles 0.25 mm long and only 2.3 times longer than wide. Anthocodial spicules form a crown with collaret. A specimen was sent to Dr. F. M. Bayer at the U.S. National Museum for confirmation since the anthocodiae did not appear to be exsert as described in his 1961 paper. Dr. Bayer identified it as E. calyculata and believed it to be coronata. He thought that anthocodial differences in the dried specimen could be due to circumstances at the time of preservation and was not a reliable feature. The typical form ranges from Bermuda, Bahamas, and throughout the Carib- bean. E. calyculata forma coronata was reported from Campeche Bank, Mexico at 36 m by Bayer (1961), from Columbia by Kocurko (1987), and from Belize by Lasker and Coffroth (1983). Roatan specimens were collected at Caribe Point from a depth of about 10m.

+- kallos. H. Cortical scaphoids of Pseudopterogorgia acerosa. I. Cortical scaphoids of Pseudopterogorgia americana. J. Cortical scaphoid of Pseudopterogorgia humme/incki. K. Cortical scaphoid of Pseudop- terogorgia e/isabethae. L. Scaphoids from outer cortex of Gorgonia venta/ina. M. Scaphoids from outer cortex of Gorgonia mariae. N. Double-headed spicule from outer cortex of E/lisella elongata. 220 BULLETIN OF MARINE SCIENCE, VOL. SO, NO. I, 1992

Muriceopsis flavida (Lamarck, 1815) Colonies are tall, plumose and pinnately branched in all directions. Branchlets are slender, cylindrical and bear small openings on all sides, Roatan specimens were yellow in color, but light brown and gray to purple colonies have been reported. The outer layer contains some unilaterally spinose spindles and asymmetrical clubs (Fig. 3C). A few spindles reach lengths of 0.4 mm and clubs average about 0.22 mm. The axial sheath contains acute purple spinose spindles to 0.3 mm. This species was collected from the fore-reef slope at Oak Ridge at a depth of about 20 m. It was reported by Opresko (1973) from patch reefs around Miami, Florida, and by Lasker and Coffroth (1983) from the fore-reef ridge at Belize. The species ranges throughout the Caribbean to depths of 33 m.

Plexaurella dichotoma (Esper, 1791) Colonies are bushy and dichotomously branched. Branches are 7-18 mm in diameter with rigid, blunt ends. The rind is usually raised around the slit-like apertures. Dried specimens are often yellowish in color. Plexaurella spicules are dominantly or exclusively quadriradiate, resembling butterflies. P. dichotoma is distinguished by stout quadriradiates and coarsely sculptured triradiates in the middle cortex (Fig. 3D). The axial sheath contains triradiates, spindles, and quadriradiates 0.35 mm long. This species was found at Horseshoe Reef and Caribe Point at moderate depths of 8-15 m. It was also observed at Oak Ridge on the fore-reef slope. It is common from Bermuda to Brazil and throughout the Caribbean to depths of 49 m.

Muricea muricata (Pallas, 1766) Colonies are laterally branched in one plane but not pinnate. Calyces are pointed and shelf-like with large projecting spicules. Dried specimens are usually yellow to tan in color, but gray colonies have been reported. Calycular spindles bear prickles or small spines but no long terminal spikes. Spindles ofthe outer cortex are covered with low tubercles or may have tubercles and simple (not branching) spines (Fig. 3E). A diagnostic feature of the species is the conspicuous flattening of the axis at the branch axils. The axial sheath contains tuberculated blunt rods and spindles near the branch tips, and globular or ovate sclerites near the base. This species was very abundant at Horseshoe Reef and Oak Ridge on the fore- reefslope at moderate depths. It was reported by Lasker and Coffroth (1983) from sand flats and fore-reef habitats at Belize. Its distribution ranges from Florida to Curacao and is reported to depths of 10 m. (Kinzie, 1973).

Family Gorgoniidae The Gorgoniidae is characterized by cortical spicules with transverse belts of tubercles, and no clubs. Spicules are small, rarely exceeding 0.2 mm.

Pseudopterogorgia bipinnata (Verrill, 1864) Pseudopterogorgia colonies are plume-like and pinnately branched with canoe- shaped scaphoids in the outer cortex. P. bipinnata tends to branch in one plane with secondary branchlets often bifurcating to form bipinnate colonies. Branchlets are typically stiff, blunt and opposite, but colonies collected at Roatan did not KEITH: GORGONIANS OF ROATAN 221 have the typical growth form. Branchlets were not strictly opposite and up to 8 cm in length. Polyps were mostly, but not strictly, marginal. The growth form of a colony can be drastically influenced by environmental factors and Dr. F. M. Bayer ofthe U.S. National Museum (pers. comm.) considered the aberrant forms at Roatan probably the result of local conditions. Dried specimens are yellow in color. Cortical spicules consist of scaphoids ranging from 0.11-0.13 mm. Tubercles on the convex and concave sides are about equal forming two medial belts, or collars (Fig. 3F). Belted spindles are present up to 0.17 mm in length. This species was relatively common in the deeper parts of the reef and has been reported at depths ranging from 14-55 m. Specimens were collected from the fore-reef slope at Roatan at a depth of about 20 m.

Pseudopterogorgia kallos (Bielschowsky, 1918) Colonies are thick and plumose. Branchlets are 4 mm apart or less, strongly ascending and pinnate, but not strictly opposite or in one plane. Branchlets are nearly cylindrical, most ranging in length from 1-3.5 cm. Dried colonies are yellow in color. Cortical spicules contain small stout scaphoids 0.1-0.13 mm long, many of which have the space between transverse crests filled in on the convex surface except between the two medial belts (Fig. 3G). The species has been reported from Florida to Cuba (Bayer, 1961), and from Belize where it comprised about 32% of the gorgonians of the fore reef at Carrie Bow Cay (Lasker and Coffroth, 1983). It was collected at Caribe Point at a depth of about 5 m.

Pseudopterogorgia acerosa (Pallas, 1766) Colonies are usually tall and plumose with marginal calyces, but do not have a slimy surface as in P. americana. Branches are flattened and branched mostly in one plane. Branchlets are typically long, reaching lengths of about 11 cm, but colonies collected from a sand flat at Caribe Point had branchlets of about 4 cm or less. The colony color may vary from light purple to yellow. Cortical spicules include uniformly curved scaphoids up to 0.15 mm long. Most are smooth or finely echinulate on the convex surface (Fig. 3H). Anthocodial rods are present. This species is widespread, occurring at Bermuda, Bahamas, Gulf of Mexico and throughout the Caribbean. It was characterized as an inshore species by Opresko (1973) but has been reported to depths of 33 m. It comprised nearly 12% of the fore-reef species at Carrie Bow Cay, Belize (Lasker and Coffroth, 1983). Colonies were collected at Roatan from a shallow sand flat at Caribe Point at a depth of 1.5 m.

Pseudopterogorgia americana (Gmelin, 1791) Colonies are large and plumose with long branches and smaller pinnately ar- ranged branchlets. Living colonies are very slimy to the touch from large quantities of mucus. In dried specimens, branch lets are stuck together by the mucus. Colony color is pale yellow. The outer cortex contains strongly curved scaphoids up to 0.14 mm in length which are distinctly echinulate on the convex side. Their tips are pointed and often recurved (Fig. 31). Anthocodial rods are lacking. 222 BULLETIN OF MARINE SCIENCE, VOL. 50, NO. I, 1992

This species occurs at Bermuda, Florida and throughout the Caribbean. It is particularly common in shallow water but has been reported to depths of 45 m. According to Lasker and Coffroth (1983), the species made up nearly 19% of the fore-reef gorgonians at Belize. At the Swan Islands, colonies were collected from areas of mixed sand and coral rubble with scattered reef patches at depths of about 15 m. Roatan colonies were collected from sandy back-reef areas at Caribe Point and from the shallow fore-reef zone at Oak Ridge.

Pseudopterogorgia hummelincki Bayer, 1961 Colonies are pinnately branched and spread in one plane. Some branchlets are up to 8 em, but most are 3-4 em. Dried specimens are creamy white with a pinkish-purple base. Roatan colonies differed from those of Bayer (1961) by the length of the branchlets which were up to 8 cm in Roatan specimens and 3 cm in the holotype. Cortical spicules include moderately curved scaphoids 0.1-0.15 mm long. They are echinulate on the convex surface and the concave surface and sides bear tubercules. The ends are usually pointed, but blunt scaphoids sometimes occur (Fig. 3J). Acute belted spindles 0.11-0.19 mm in length also occur and are larger near the axis. Light purple spindles occur in the axial sheath. This species is known from the type locality in Anguilla (Bayer, 1961). The occurrence at Roatan extends its distribution to the Northwestern Caribbean. It was collected at Caribe Point from a back-reef area composed of mixed sand and coral rubble at a depth of about 5 m.

Pseudopterogorgia elisabethae Bayer, 1961 Colonies are pinnately branched in one plane with relatively short (2.5-5.5 em), flattened branchlets about 2 mm wide. Polyps are marginal. Dried colonies are pinkish-purple in color but have been reported to be yellow in alcohol by Bayer (1961). The cortex contains large scaphoids which range up to 0.26 mm long. They are light purple and smooth or moderately echinulate on the convex surface (Fig. 3K). Simple belted spindles are also present. Most are about 0.26 mm, but some range up to 0.34 mm which is slightly longer than previously described for this species. Anthocodial rods up to 0.2 mm are present which slightly exceed the length of previously described specimens. The species has been reported from the Bahamas, Florida Keys and Cuba. It was reported from Belize on sand flats by Lasker and Coffroth (1983). The species was collected at Roatan in shallow water from a sandy back-reef area at Caribe Point. Although most common at shallow to moderate depths, it was reported by Kinzie (1973) to depths of 72 m.

Gorgonia ventalina Linnaeus, 1758 The colony consists of a flat, net-like fan formed by anastomosing branches which are flattened in the plane of the fan. A similar Caribbean species, G. flabellum, has branches compressed perpendicular to the plane of the fan. Colonies are most commonly purple, but may be yellow or white. Spicules consist of scaphoids which are echinulate on the convex surface (Fig. 3L). This species is widespread throughout the Caribbean. Bayer (1961) reported G. ventalina to be restricted to the outer reef and reef patches along the Florida Keys, and according to Verrill (1907) it reached maximum growth in the outer KEITH: GORGONIANS OF ROATAN 223 reefs at Bermuda at depths of 3-7 m. Guzman and Cortes (1985) found it to be very abundant in 2-4 m of water along the Caribbean coast of Costa Rica and Lasker and Coffroth (1983) reported the species from all habitats studied at Belize. Tortora and Keith (1980) found it to be one of the most abundant gorgonians at the Swan Islands, particularly at depths of 3-10 m. At Roatan it was found at all localities including sand flats attached to coral rubble, patch reefs, and the fore reef off Oak Ridge. Its reported depth range is 0-30 m.

Gorgonia mariae Bayer, 1961 Colonial structure is a net-like fan formed by anastomosing branches. This species can be distinguished from other Gorgonia by the large mesh size. Dried specimens are yellow, but some deeper water forms have been reported to be nearly white. Bayer (1961) found some colonies to have a purple tinge at the base. Spicules consist of scaphoids and spindles. The convex sides of the scaphoids are smooth (Fig. 3M). Shorter scaphoids (0.07 mm) are blunt and stubby; whereas, longer ones are acute reaching lengths of 0.16 mm. Spindles are up to 0.17 mm long and are acute with tubercles in transverse belts. This is the only species of fan coral that has scaphoids with smooth, convex sides. This species was reported by Bayer (1961) from Cuba and localities along the Greater Antilles. Lasker and Coffroth (1983) found it to occur in the fore reef and fore-reef ridge at Belize. It has been recorded at depth ranges from a little below low tide to about 40 m (Bayer, 1961). A single specimen was collected from the fore-reef slope at Oak Ridge at a depth of about 20 m.

Family Ellisellidae The Family Ellisellidae is distinguished by a calcified axis with no chambered central core and double-headed (dumbbell-shaped), amber-colored spicules.

Ellisella elongata (Pallas, 1766) Colonies are large and dichotomously branched with long, slender whip-like branches 2 to 3 mm thick near the top. Calyces are hemispherical and low with apertures directed upward. Dried colonies are reddish-brown in color. Spicules of the outer cortex contain numerous small amber-colored, dumbbell- shaped capstans (Fig. 3N). Most are about 0.06 mm but range from 0.048-0.079 mm. The axial sheath contains clear and light amber-colored, flattened capstans 0.07-0.09 mm in length. They are not as heavily tuberculated as those of the cortex. This species is distributed from the northern part of the Gulf of Mexico, Florida, and through the Antilles to Brazil at depths of 24-219 m. Specimens were collected at Oak Ridge from the reef face of the fore reef at about 25 m. This is the first record of E. elongata from the Caribbean coast of Central America.

DISCUSSION The diversity and abundance of gorgonians at Roatan appear comparable to those of Yucatan, Belize and Costa Rica. Reefs at the Swan Islands, which are located about 90 miles northeast of Honduras, appear impoverished when compared to those of Roatan. Only 52% of the species of gorgonians reported from Roatan were present at the Swan Islands but all of the Swan Island species reported by Tortora and Keith (1980) were present at Roatan. The increased diversity of 224 BULLETIN OF MARINE SCIENCE, VOL. 50, NO. I, 1992

Table 1. Geographic distribution of shallow-water gorgonians along the Caribbean coast of Central America. YUCA = Yucatan, ROTN = Roatan, BELZ = Belize, SWIS = Swan Islands, PROY = La Providencia, SAND = San Andres Island, COST = Costa Rica, + = present, - = absent

Species YUCA ROTN BELZ SWIS PROV SAND COST Briareum asbestinum + + + + + + + lciligorgia schrammi + Erythropodium caribaeorum + + + + Thesea plana + Plexaura homomalla, typical form + + + + + Plexaura homomalla forma kukenthali + + + Plexaura flexuosa + + + + + + + Pseudoplexaura porosa + + + + + + + Pseudoplexaura flagellosa + + + + Pseudoplexaura wagenaari + + + + Pseudoplexaura crucis + Eunicea laxispica + + Eunicea palmeri + Eunicea mammosa + + + + + + Eunicea succinea. typical form + + Eunicea succinea forma plantaginea + + Euniceafusca + + + Eunicea laciniata + + + Eunicea tourneforti typical form + + + + + + Eunicea tourneforti forma atra + + + Eunicea c1avigera + + Eunicea knighti + + Eunicea calyculata, typical form + + + Eunicea calyculata forma coronata + + Muriceopsis sulphurea + Muriceopsis flavida + + + + + + Muriceopsis petila + + Plexaurella dichotoma + + + + + + Plexaurella nutans + Plexaurella grisea + + + + Plexaurella pumila + Plexaurella fusifera + Muricea atlantica + + + Muricea pin nata + Muricea laxa + Muricea elongata + Muricea muricata + + + Pseudopterogorgia bipinnata + + + + Pseudopterogorgia kallos + + + Pseudopterogorgia rigida + + + Pseudopterogorgia blanquillensis + Pseudopterogorgia acerosa + + + + + + + Pseudopterogorgia americana + + + + + + Pseudopterogorgia hummelincki + Pseudopterogorgia elisabethae + + + Gorgonia ventalina + + + + + + + Gorgonia mariae + + + Gorgonia flabellum, typical form + + Gorgonia flabellum forma occatoria + Pterogorgia citrina + + Pterogorgia anceps + + + Pterogorgia quadalupensis + + El/isella elongata + Total 38 23 39 12 9 17 23 KEITH: GORGONIANS OF ROATAN 225 gorgonians probably results from increased habitat diversity and greater protection from severe storms afforded to corals at Roatan by the mainland. Table 1 shows the distribution of gorgonians along the Caribbean coast of Central America. Gorgonians from other studies that were not identified to species are omitted from the table, thus the actual diversity from some areas is slightly greater than indicated. There are a number of unresolved gorgonian species that have come to light since Bayer's 1961 study, and a faunal revision is needed to put Caribbean gorgonians on a firm taxonomic foundation (Bayer, pers. comm.). In studies where growth forms of species were not differentiated, they are included in Table I as typical forms. Forty-eight species and five growth forms have been identified along the Ca- ribbean coast of Central America from Yucatan to Costa Rica. Fourteen have been collected from single localities. Two Roatan species, Pseudopterogorgia hummelincki and Ellisella elongata have not been reported previously from the Central American coast. The greatest diversities have been reported from the east coast of Yucatan by Dahlgren (1989) and Jordan (1979), and from Belize by Muzik (1982) and Lasker and Coffroth (1983). The fact that these reefs have received more attention than other reefs along the Caribbean coast of Central America may in part account for the greater number of reported gorgonian species.

ACKNOWLEDGMENTS

Appreciation is expressed to Tarleton State University for the Organized Research Grant which made this study possible. I also wish to thank Dr. F. M. Bayer, National Museum of Natural History, for his assistance in confirming some of the gorgonian identifications.

LITERATURE CITED

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DATEACCEPTED: July II, 1991.

ADDRESSES:Department of Biological Sciences, Tarleton State University, Box T-219, Tarleton Sta- tion. Stephenville, Texas 76402.