The geographic distribution of Ophioblenna antillensisLütken, 1859 is extended inside the Gulf of Mexico. This species is otherwise known in the Caribbean region as the “slimy snake of the Antilles”, and is recognizable by soft skin covering the entire body, arms 5 times the disc diameter with big dorsal arm plates, and 7 completely naked, pointed and thin arm spines.
La distribución geográfica de Ophioblenna antillensisLütken, 1859 se extiende dentro del golfo de México. Esta especie es bien conocida en la región caribeña como la “ofiuro serpiente de las Antillas” y es reconocible porque su disco está cubierto por piel delgada, sus brazos son 5 veces el diámetro del disco con placas dorsales grandes, 7 espinas braquiales completamente desnudas, puntiagudas y delgadas.
The family Ophiomyxidae comprises 28 genera, among which Ophioblenna is a monotypic genus, with the species Ophioblenna antillensisLütken, 1859. The distribution of this species is off The Bahamas, Puerto Rico, Saint Thomas, Belize, and Panama (Hendler, Miller, Pawson, & Kier, 1995). However, the bathymetrical distribution of Ophioblenna suggests that it could be more widespread in the Caribbean and Gulf of Mexico. Although recent studies in this area (Laguarda-Figueras, Hernández-Herrejón, Solís-Marín, & Durán-González, 2009) and recent detailed checklists of the Gulf of Mexico echinoderms have been published (Pawson, Vance, Messing, Solís-Marín, & Mah, 2009), this species has never been reported in Mexican waters. On August 2009 and April 2013, O. antillensis was found as part of the shallow brittle-star assemblages of the Gulf of Mexico in Alacranes Reef at 2m, and Blake Reef, occurring at 24m depth.
Ophioblenna antillensis lives under rubble on shallow reef flats, beneath dead coral slabs in the turbulent spur and groove zone, and in the interstices of corals on the fore reef slope (Hendler et al., 1995).
The specimens collected were compared with the diagnosis published by Lütken (1859) and deposited in the Colección Nacional de Equinodermos de México, Instituto de Ciencias del Mar y Limnología, Universidad Nacional Autónoma de México (ICML-UNAM).
Order Ophiurida Müller and Troschel, 1840
Family Ophiomyxidae Ljugman, 1867
Genus OphioblennaLütken, 1859
Ophioblenna antillensis Lütken, 1859 (Fig. 1A–F)
Figure 1.Ophioblenna antillensis: A, dorsal side; B, ventral side; C, detail of the ventral side showing the mouth and jaws; D, lateral view of the fan shaped arm spines; E, ventral side of an arm showing the tentacle scales and shape of the ventral arm plates; F, dorsal side of an arm showing the dorsal arm plates.
(0,33MB).Ophioblenna antillensisLütken, 1859: 239–240, Pl. 4, Fig. 4; 4; Ljungman, 1866: 327; Verrill, 1899: 379; H. L. Clark, 1901: 251; A. H. Clark et al., 1920: 41; Maddocks, 1987: 727; Hendler et al., 1995: 37, 98–99, Fig. 33; Hernández-Díaz, 2011: 27, 29, 30, 40, 17.
Disc pentagonal, covered with soft skin, lacking disc scales. Oral shields covered by soft skin, large and wide, proximally pointed and distally rounded. Seven oral papillae, outermost small, next pair wider and innermost one more pointed; teeth are narrower. Arms 5 times disc diameter. Dorsal arm plates of great size, on younger specimens oval, in adults broader, more arched with rounded margins. Arm spines 7 in number, about half as long as the joint, completely naked, pointed, thin, strongly serrated and hyaline, resembling Ophiothrix.
DescriptionDisc small (diameter 15mm in specimen from Blake Reef, 19mm in specimen from Alacranes Reef), pentagonal, covered with smooth skin. Radial shields covered by skin. Each jaw with 6–7 oral papillae, outermost rectangular with rounded tips, next 3 pairs pointed, infradental thicker and pointed. Oral shields elliptical, much broader than long, touching first lateral arm plate, with rounded tips. Adoral shields narrow. Genital slits prominent, thicker, not reaching periphery of disc. Five arms, longest one 95mm long. Dorsal arm plates large, oval, twice as wide as long; some arm segments fragmented. Ventral arm plates quadrangular, covered by skin. Lateral arm plates enlarged and flared at distal ends; second lateral arm plate particularly enlarged, nearly reaching edge of disc. Six to 7 arm spines proximally in Blake Reef specimen and 7–8 arm spines in Alacranes Reef specimen, ventralmost the largest (2.5mm), reaching almost 1 and one-half arm segments, distally 5–6 arm spines, terminal part of arms with 4–5 arm spines; pointed, hyaline, serrated, directed downwards. Tentacle pores large, widely open; each one armed with 2 large, elongated tentacle scales, outermost pore thicker and shorter than innermost one.
Color variation. The dorsal side of the Blake Reef specimen has a brown disc with yellow spots, the arms are also dark brown, and some arm segments and arm spines possess yellowish bands. The ventral surface of the disc is dark brown with yellow spots larger than those of the dorsal side. The disc of the Alacranes Reef specimen has a uniform purplish color, the arms are light purple; distally, some arm segments possess a yellowish band; spines are banded with yellow stripes; ventrally the mouth area is beige with brown interradial areas spotted with beige motes (Fig. 1).
Geographical distributionOff The Bahamas, Belize, Puerto Rico, Saint Thomas and Panama (these localities lack precise geographical coordinates; Hendler et al., 1995; Hotchkiss, 1982), Veracruz and Yucatán, Mexico (Fig. 2). The latter 2 records expand its geographic distribution to the southwest Gulf of Mexico.
Bathymetric distribution. 1–24m (Hendler et al., 1995; Hernández-Díaz, 2011).
Material examinedICML-UNAM 3.197.0, 1 specimen; Blake Reef, Gulf of Mexico (20°45′37.5″N, 96°59′31.1″W); 14 April 2013; 24m depth. ICML-UNAM 10162, 1 specimen; Alacranes Reef, Gulf of Mexico, Yucatán, Mexico (22°27′09.8″N, 89°45′44.9″W), coral rubble on shallow reef flat; 13 August 2009, 2m depth.
The genus Ophioblenna is poorly known and not well documented. Lütken (1859) described the genus for the West Indies, with O. antillensis as the only species. However, it has also been mentioned as Ophialcaea glabra H. L. Clark, 1901 and Ophiomitrella glabra H. L. Clark, 1901, but further information is needed regarding the systematic position of this species and the latter ones. Clark (1901) mentioned that the oral papillae of Ophialcaea glabra were very similar to those of Ophiacantha, but the taxon differed sharply from that genus in the arrangement of the dorsal arm plates, the arm spines, and the covering of the disc. In fact, the soft skin covering the disc, the pointed oral papillae and the number of arm spines characterized the genus Ophioblenna.
It has been reported that the ostracod Pontocypria hendleri is a commensal of this species (Hendler et al., 1995; Maddocks, 1987).
Ophioblenna antillensis was already reported for Mexico (Solís-Marín et al., 2013). However, recent analysis of the material deposited at ICML-UNAM shows that these records correspond to Ophiomyxa flaccida, hence these are the first records of O. antillensis for the Gulf of Mexico; they extend the geographic distribution of the species and highlight the need for further studies on the taxonomy and diversity of the echinoderm fauna of the Gulf of Mexico.
We thank Alicia Durán González (ICML, UNAM) for technical support. We also thank Conabio (Grant FB1194) for supporting the project “Esponjas, corales escleractinios, equinodermos y peces de los arrecifes coralinos del norte y sur de Veracruz”; SEP for partial support through “Bases para el Análisis y Síntesis de los Sistemas Costeros de Veracruz”, conducted within the framework of the network for “Análisis y síntesis de la zona costera veracruzana, golfo de México” (RASZCOV). Permits (Dgopa. 02698.260312.0743 and Dgopa. 5458.170512.1381) were issued by Sagarpa. Conacyt-Semarnat, for financial support for expedition to Alacranes Reef (Project No. 10828).
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