Caribbean Journal of Science, Vol. 41, No. 3, 583-599, 2005 Copyright 2005 College of Arts and Sciences University of Puerto Rico, Mayagu¨ez Two New Brittle Star Species of the Genus Ophiothrix (Echinodermata: Ophiuroidea: Ophiotrichidae) from Coral Reefs in the Southern Caribbean Sea, with Notes on Their Biology GORDON HENDLER Natural History Museum of Los Angeles County, 900 Exposition Boulevard, Los Angeles, California 90007, U.S.A. [email protected] ABSTRACT.—Two new species, Ophiothrix stri and Ophiothrix cimar, inhabit shallow reef-platforms and slopes in the Southern Caribbean, and occur together at localities in Costa Rica and Panama, nearly to Colombia. What appears to be an undescribed species resembling O. cimar has been reported from eastern Venezuela. In recent years, reefs where the species were previously observed have deteriorated because of environmental degradation. As a consequence, populations of the new species may have been reduced or eradicated. The new species have previously been mistaken for O. angulata, O. brachyactis, and O. lineata. Ophiothrix lineata, O. stri, and O. cimar have in common a suite of morphological features pointing to their systematic affinity, and a similar pigmentation pattern consisting of a thin, dark, medial arm stripe flanked by two pale stripes. Ophiothrix lineata is similar to Indo-Pacific members of the subgenus Placophiothrix and closely resembles Ophiothrix stri. The latter is extremely similar to O. synoecina, from Colombia, and both can live in association with the rock-boring echinoid Echinometra lucunter. Although O. synoecina is a protandric hermaphrodite that reportedly broods its young externally, the new species are gonochoric and do not brood. Their eggs are of a size indicative of abbreviated larval development, and the gametes of O. stri produce demersal embryos that develop within a large, adhesive fertilization envelope. The new species and related forms may belong to one of several clades containing shallow-water Caribbean Ophiothrix species with abbreviated development and relatively restricted larval dispersal. KEYWORDS.—Abbreviated demersal development, brooding, Comactinia, Echinometra, Placophiothrix INTRODUCTION drawn the attention of underwater photog- raphers. Therefore, frustration created by The brittle stars of the family Ophiotri- the unsettled taxonomy of ophiotrichids is chidae are readily distinguished by the felt not only by systematists. stumps, spines, and spinelets on their The confusion engendered by ophiotri- disks, their long, thorny arm spines, and an chid taxonomy is a long-standing problem oral armament consisting solely of dental in the Caribbean region where the common papillae. However, the distinctions among Ophiothrix species are extremely variable, genera within the family are problematical, and the variability of the very rare species and the identification of ophiotrichids has has not been characterized (Hendler et al. been a continuing “source of considerable 1995). Under the circumstances, it is not trouble to systematists owing to the great surprising that the occurrence of some variability of many of the species” (A. M. Ophiothrix species, even accessible wide- Clark 1966:637). Due to their abundance spread species, has gone undetected. In the and ubiquity in shallow, warm-water ma- present contribution, two such new species rine habitats, ophiotrichids in the genus of Ophiothrix are described, which live on Ophiothrix have been studied in nature and coral reefs from Costa Rica to Colombia. the laboratory by biologists in various dis- They were most recently observed and col- ciplines. The brilliant colors of some spe- lected in Bocas del Toro Province, Panama, cies, and their association with attractive at sites that are relatively unaffected by the corals and sponges, have consistently regional deterioration of coral reefs 583 584 GORDON HENDLER (Guzmán and Guevara 1998a, b, 1999). survey sponsored by the STRI’s Bocas Re- However, it is not know if both species still search Station, and in 1986 and 1987 at survive at severely impacted sites where nearby Costa Rican localities during a they occurred in previous decades. Their study of Cahuita National Park. The results populations may have been reduced or are also derived from specimens of the Al- eradicated during the decline of coral reefs lan Hancock Foundation Pacific Expedi- that is manifested throughout the Carib- tions deposited in the Natural History Mu- bean, largely as a consequence of human- seum of Los Angeles County (LACM). caused environmental change (Gardner et Type specimens of related species from the al. 2003; Birkeland 2004). echinoderm collections of the Museum of In the vicinity of Panamanian reefs near Comparative Zoology of Harvard Univer- Galeta, and in the San Blas Islands where I sity (MCZ) and the National Museum of found both of the new species in the 1970s, Natural History of the Smithsonian Institu- there have been several destructive oil tion (USNM) were compared as well. spills, and declines in coral cover attributed Living and preserved specimens were to coral bleaching, coral mining, and un- examined with a stereomicroscope and planned coastal development (Birkeland et measured with a calibrated ocular mi- al. 1976; Guzmán et al. 1994; Guzmán 2003). crometer, calipers, or millimeter ruler, as At Cahuita National Park, Costa Rica, necessary. Animals were anesthetized us- where I collected them in the 1980s, the reef ing magnesium chloride or Epsom salts so- was subsequently damaged by coastal up- lutions prior to preservation in ethanol, and lift triggered by an earthquake, and by the some specimens were dried. Descriptive impact of siltation and other anthropogenic statistics are based exclusively on alcohol- stressors (Cortés and Risk 1985; Cortésetal. preserved animals. To prepare skeleton 1993; Fonseca 2003). The situation at Cale- structures for scanning electron micros- donia Bay, where the species were first col- copy, soft tissue was removed from alco- lected in the 1930s, has not since been re- hol-preserved material using dilute sodium ported (Garth 1945), but the condition of hypochlorite solution, and the specimen the reefs has probably deteriorated there, as was washed in water and air-dried prior to it has elsewhere in Panama (Guzmán 2003). sputter coating. The terminology employed The similarity of the new species to each for morphological characters follows Hen- other, and to congeners including the dler et al. (1995). Color patterns running the highly variable Ophiothrix angulata (Say, length of the arm are referred to as stripes; 1825), has hampered their recognition and those running across the arm are called study. Therefore, my objective is to facili- bands. Abbreviations used are dd (disk di- tate their identification. For the same rea- ameter) and AL (arm length). Type speci- son, I also refer to what may be another mens of the new species are deposited at similar, undescribed species from Venezu- the LACM, USNM, and Museo de Zoología ela (Zoppi de Roa 1967). A further aim is to of the Universidad de Costa Rica (UCR). report on some significant aspects of their reproduction and ecology, and their rela- SYSTEMATIC ACCOUNT tionship to other species of Ophiothrix. Family Ophiotrichidae Ljungman, 1867 Genus Ophiothrix Müller and Troschel, MATERIALS AND METHODS 1840 Ophiothrix cimar, new species Initial studies and collections were done FIGURE 1A-F in the vicinity of the Galeta Marine Labo- ratory of the Smithsonian Tropical Re- Holotype.—COSTA RICA, LIMON search Institute (STRI), from 1971 to 1975. PROV.: (LACM 1987-68.3), Sta. CR 87-31, 24 However, the present contribution is May 1987, 9°44.97Ј N, 82°49.3Ј W, NE of largely based on observations and collec- Sloth River mouth, 0-1 m, coll. G. Hendler tions gathered in 2003 during a regional and R. W. Peck. NEW SOUTHERN CARIBBEAN BRITTLE STARS 585 Paratypes.—COSTA RICA, LIMON 82°48.7Ј W, Punta Cahuita Reef, 1-2 m, coll. PROV.: (LACM 1986-106.2), 8 alc, Sta. CRA G. Hendler and R. W. Peck; (LACM 1987- 86-1, 26 Jul. 1986, 9°44.18Ј N, 82°48.6Ј W, 68.2), 1 alc, Sta. CR 87-31, 24 May 1987, Punta Cahuita Reef, 1-3 m, coll. G. Hendler; 9°44.97Ј N, 82°49.3Ј W, NE of Sloth River (LACM 1986-115.1), 1 alc, Sta. CRA 86-8, 27 mouth, 0-1 m, coll. G. Hendler and R. W. Jul. 1986, 9°37.9Ј N, 82°36.97Ј W, off Punta Peck. PANAMA, BOCAS DEL TORO Mona (Punta Carreta), 6-15 m, coll. G. Hen- PROV.: (LACM 2003-51.6), 1 alc, Sta. BDT dler; (LACM 1986-137.1), 1 alc, Sta. CRA 03-4, 4 Aug. 2003, 9°20.66Ј N, 82 ° 10.33Ј, 86-23, 28 Jul. 1986, 9° 44.18Ј N, 82° 48.6Ј W, Wild Cane Key, N. Bastimentos Id., 0.9-4.2 Punta Cahuita Reef, 2-9 m, coll. G. Hendler; m, coll. G. Hendler et al.; (LACM 2003- (LACM 1986-141.2), 1 alc, Sta. CRA 86-27, 64.3), 1 alc, Sta. BDT 03-16, 7 Aug. 2003, Ј Ј 29 Jul. 1986, 9°44.18 N, 82°48.6 W, Punta 9°27.2Ј N, 82°18.02Ј W, S. Swan Key, 3 m, Cahuita Reef, 2-6 m, coll. G. Hendler; coll. G. Hendler et al.; (LACM 2003-65.3), 1 (LACM 1986-154.2), 3 alc, Sta. CRA 86-37, alc, Sta. BDT 03-17, 7 Aug. 2003, 9°25.6Ј N, Ј Ј 31 Jul. 1986, 9°39.7 N, 82°45.53 W, off Pu- 82°19.5Ј W, Boca del Drago, N. W. Colon erto Viejo, 1-4 m, coll. G. Hendler; (LACM Id., 4.5 m, coll. G. Hendler et al. PANAMA, 1986-197.2), 1 alc, 29 Oct. 1986, 9°44.18Ј N, Ј COLON PROV.: (LACM 1939-181.3), 1 dry, 82°48.7 W, Punta Cahuita Reef, 1-5 m, coll. Sta. AHF A8-39, R/V Velero III, 4 Apr.