Ophiothela angulata
Creators: name: Alitto, Renata A. S.
name: Bueno, Maristela L.
name: Guilherme, Pablo D. B.
name: Domenico, Maikon Di
name: Christensen, Ana Beardsley
name: Borges, Michela
Publisher: name: Zenodo
Year: 2018
Subjects: Biodiversity
Taxonomy
Animalia
Echinodermata
Ophiuroidea
Ophiurida
Ophiotrichidae
Ophiothela
Ophiothela angulata

description: Ophiothrix angulata (Say, 1825)
(Fig. 6)
Type locality. Charleston Harbour, South Carolina (United States).
Maximum size. dd up to 10 mm (Borges & Amaral 2005).
Material examined. 22 specimens (dd: 1.1–8.6 mm). Subtidal: ZUEC OPH 2172, St. VI, 1 spm; ZUEC OPH 2177, St. XII, 1 spm; ZUEC OPH 2194, St. XI, 4 spms; ZUEC OPH 2282, St. XXVI, 6 spms; ZUEC OPH 2356, St. XXXIV, 1 spm. From rocky shore in sponge: ZUEC OPH 2149, St. 2C, 3 spms; ZUEC OPH 2433, St. 10C, 1 spm; ZUEC OPH 2435, St. 11C, 1 spm; ZUEC OPH 2439, St. 12C, 1 spm, ZUEC OPH 2455, St. 15C, 3 spms.
Description. Disc: (dd: 5.7 mm) pentagonal, covered by small hyaline, bifid and/or trifid spines. Radial shields triangular, twice as long as wide, one-third of dd, united distally and separated proximally, covered by bifid and/or trifid spines (Fig. 6A). Ventral interradius covered by scales with small spines, smaller than the dorsal, except near the oral shields and bursal slits (Fig. 6B). Oral shields twice as wide as long, tapered proximally and with a slight projection at the distal edge. Madreporite larger than other oral shields, but with a similar shape. Adoral shields broadened distally and separated proximally. Depression between two oral plates. A cluster of dental papillae on the dental plate and without lateral oral papilla. Oral tentacle pore visible (Fig. 6C).
Arms: dorsal arm plates fan-triangular, as long as wide and contiguous (Fig. 6D,F). Ventral arm plates with distal edge concave, proximal edge straight, lateral edges convex and slightly as long as wide (Fig. 6E,G). One tentacle scale. Five to eight long arm spines (longest about three arm joints), vitreous and denticulate, the second to ventral-most being the smallest and the ventral-most modified into a hook with hyaline teeth facing the disc (Fig. 6E).
Lateral arm plates (Fig. 6H, I): general outline: ventral portion projecting ventro-proximalwards; ventro-distal tip not projecting ventralwards. Outer surface ornamentation: trabecular intersections protruding to form knobs larger than stereom pores on most of outer surface. Outer proximal edge: surface lined by discernible band of different stereom structure, restricted to central part; without spurs; central part protruding; surface without horizontal striation. Spine articulations: on elevated portion not bordered proximally by ridge, middle spine articulation(s) larger; distance between spine articulations increasing dorsalwards. Lobes merged at their proximal tips by smooth connection, dorsal lobe clearly larger than the ventral lobe; lobes parallel, bent, with tilted orientation; stereom with perforations; sigmoidal fold absent. Inner side, ridges and knobs: dominated by two separate central knobs on inner side with a ridge; without additional dorsal structure on inner side; single large perforation on inner side.
Vertebrae: zygospondylous of universal type and keeled. Large groove on proximal side of vertebrae dorsally corresponding to distalwards projecting dorso-distal muscular fossae of distal side (Fig. 6J). Zygocondyles dorsalwards converging and zygosphene fused with pair of zygocondyles (Fig. 6K). Dorso-distal muscular fossae transformed distalwards clearly projecting beyond zygocondyles (true keel) (Fig. 6L). Zygosphene projecting beyond ventral edge of zygocondyles with projecting part longer than zygocondyles (Fig. 6M).
Taxonomic comments. The vertebrae possess a dorsal distal keel, dorsal projections, and depressions connected by dorsal accessory muscles. These are also evident at the dorsal vertebral surface. Six specimens were classified as juvenile due a bright whitish circle in the center of the disc and absence of central scales. Various color patterns are reported in this species, varying from pink to dark violet, and sometimes displaying a black or white stripe on the arm surface (Tommasi 1970; Hendler et al. 1995; Manso et al. 2008). Specimens from type-locality (National Museum of Natural History, Smithsonian Institution, accession number E24138) were compared with our samples. The only difference observed was the shape of the ventral arm plates: slightly concave distally in our specimens while it is cordiform in specimens from type-locality. This variety of phenotypes demonstrates an imperative need for a taxonomic revision, especially when comparing populations from different regions, such as the Brazilian South-east and North-Northeast (Paim et al. 2015). The name O. angulata was applied here as that is what is currently considered valid.
Remarks. It is commonly found on rubble bottom and with other Ophiothrix and Ophiactis species, constituting the main component of the fauna associated with the biological substrate (Paim et al. 2015) particularly sponges (Tommasi 1970; Hendler et al. 1995). O. angulata has also been sampled in brown alga Sargassum spp. (Jacobucci et al. 2006), colonies of the bryozoan Schizoporella errata (Morgado & Tanaka 2001), tubes of the polychaete Phyllochaetopterus socialis (Nalesso et al. 1995), oyster banks, mangroves, seagrass beds and on sessile animals, such as Millepora sp. and gorgonians (Hendler et al. 1995). O. angulata was collected from rubble bottom with a dredge (80% of spms) or associated with the sponge Amphimedon viridis.
Distribution. Temperate Northern Atlantic (realm), Warm Temperate Northwest Atlantic (province): Carolinian and Northern Gulf of Mexico (Hendler et al. 1995; Durán-González et al. 2005; Laguarda-Figueras et al. 2005; Alvarado et al. 2008; Hernández-Herrejón et al. 2008). Tropical Atlantic (realm), Tropical Northwestern Atlantic (province): Southern Gulf of Mexico to Eastern Caribbean (Devaney 1974; Chavarro et al. 2004; Pomory 2007; Borrero-Pérez et al. 2008); Tropical Southwestern Atlantic (province): São Pedro and São Paulo Islands (Barboza et al. 2015b), Northeastern and Eastern Brazil (Alves & Cerqueira 2000; Neves et al. 2007; Gondim & Giacometti 2010; Miranda et al. 2012; Gondim et al. 2013a; Gondim et al. 2013b). Temperate South America (realm), Warm Temperate Southwestern Atlantic (province): Southeastern Brazil (Tommasi 1970; Manso & Absalão 1988; Borges & Amaral 2005; Netto et al. 2005); Rio Grande, Rio de la Plata and Uruguay – Buenos Aires Shelf (Tommasi 1970; Martínez 2008; Oliveira et al. 2010; Xavier 2010).
From intertidal up to 540 m depth (Alvarado & Solís-Marín 2013). The present study samples occurred at depths ranging from intertidal to 21.5 m.
Selected references. Say (1825): p. 145 [as Ophiura angulata]; Parslow & Clark (1963): p. 45; Monteiro (1987): p. 90, est. IXa–d; Hendler et al. (1995): p. 180, fig. 95; Borges et al. (2002): p. 58, fig. 34c,d; Borges & Amaral (2005): p. 271, fig. a–c; Manso et al. (2008): p. 194, fig. 21a–c [as Ophiothrix angulata]; Tommasi (1970): p. 60, fig.53–54; Albuquerque (1986): p. 170, fig. 27a–c; Gondim et al. (2013a): p. 67, fig. 2 f–j, 14 c; Paim et al. (2015): p. 14, fig. 9a–d [as Ophiothrix (Ophiothrix) angulata]; Ayres (1854): p. 249 [as Ophiothrix hispida].
description: Published as part of Alitto, Renata A. S., Bueno, Maristela L., Guilherme, Pablo D. B., Domenico, Maikon Di, Christensen, Ana Beardsley & Borges, Michela, 2018, Shallow-water brittle stars (Echinodermata: Ophiuroidea) from Araçá Bay (Southeastern Brazil), with spatial distribution considerations, pp. 1-66 in Zootaxa 4405 (1) on pages 21-23, DOI: 10.11646/zootaxa.4405.1.1, http://zenodo.org/record/3097993