Ophiothrix angulata ( Say, 1825 )

Santana, Alisson, Manso, Cynthia L. C., Almeida, Ana C. S. & Alves, Orane F. S., 2017, Redescription and designation of a neotype for Ophiothrix angulata (Say, 1825) (Echinodermata: Ophiuroidea: Ophiotrichidae), Zootaxa 4344 (2), pp. 291-307 : 292-297

Ophiothrix angulata ( Say, 1825)

( Figs 1–3 )

Ophiura angulata Say, 1825: 145 –146. [South Carolina, United StateS] Not Ophiothrix hispida : AyreS 1854: 249–250. [ United StateS]

? Ophiothrix angulata: Lyman 1865: 162 –164. [North and South Carolina, United StateS]

Not Ophiothrix angulata: Lyman 1882: 219 . [North and South Carolina, United StateS]

? Ophiothrix angulata : IveS 1899: 178. [Florida, United StateS]

Not Ophiothrix angulata: Verrill 1899: 19 –20. [Caribbean]

? Ophiothrix angulata: Koehler 1914: 118 –120. [South Carolina and Florida, United StateS]

? Ophiothrix angulata: H. L. Clark 1915: 269 . [North Carolina and Florida, United StateS; Mexico, Jamaica, Panama; Bahia and Rio de Janeiro, Brazil]

Not Ophiothrix angulata: H. L. Clark 1918 . [North Carolina, United StateS to Rio Plata, Argentina]

Not Ophiothrix (Ophiothrix) angulata: TommaSi 1970: 54 –60. [São Paulo, Brazil]

Ophiothrix angulata: Hendler et al. 1995: 312 . [Florida, EUA and Caribbean Sea]

Not Ophiothrix angulata : BorgeS et al. 2002. [São Paulo, Brazil]

Not Ophiothrix angulata: ManSo et al. 2008: 194 . [Bahia, Brazil]

? Ophiothrix angulata: Hernández-Herrejón et al. 2008 . [Mexico]

Not Ophiothrix angulata : BenavideS-Serrato et al. 2011: 304–305. [ Colombia]

Not Ophiothrix (Ophiothrix) angulata: Viana 2010: 9 –13. [Bahia, ESpírito Santo and Rio de Janeiro, Brazil]

Not Ophiothrix (Ophiothrix) angulata: Gondim et al. 2013: 67 –68. [Paraíba, Brazil]

Material examined. Neotype (designated herein). United States, SOuth CarOlina ( CharlestOn HarbOur ), cOll. by R. KOehler, USNM E 33764 (1 specimen) . Other specimens examined. United States, NOrth CarOlina ( BeaufOrt Channel ), cOll. 05/I/1967, C.A. Child USNM E 23906 (2 specimens) ; United States, SOuth CarOlina ( May River ), cOll. by R/ V Fish Hawk. USNM E 32615 (5 specimens) ; United States, SOuth CarOlina ( CharlestOn HarbOur ), cOll. by R. KOehler, USNM E 33764 (2 specimens) ; Cuba, ArchipelagO de LOs CanarreOs (CayO del ROlsariO), cOll 03/ III/1978, by R.B. Manning & M.L. JOnes, USMN 330836 (20 specimens) ; MexicO, Quintana ROO ( Mujeres Island ) COll. 13/VIII/1970, by M.E. DOwney, USMN E 23755 (8 specimens) . Comparative specimens. 1,026 specimens frOm Brazil previOusly identified as O. angulata (see Appendix).

Type locality. CharlestOn HarbOur , SOuth CarOlina, United States.

Diagnosis. Disc pentagOnal, rObust; spines with bifid and trifid tips, shOrter than 1 mm, cOvering bOth interradial regiOns and radial shields; disc cOverage denser On interradial regiOns; ventral arm plates heart-shaped with depressed distal edge.

Neotype description. A specimen with 5.36 mm disc diameter. Five arms, 5 times lOnger than the disc diameter. Disc pentagOnal ( Fig. 1A ), rObust, 2 mm high; interradial regiOns cOvered by small, rOunded and imbricated scales bearing shOrt spines less than 1 mm lOng, primary plates cOvered by scales, spines with bifid and trifid tips ( Figs. 1B, C ); prOpOrtiOn Of spines three bifid spines fOr One trifid spine. Disc cOverage dense, fOrming 5 large rOws Of spines On interradial dOrsal regiOn, each One with at least 8 spines between pairs Of radial shields. Radial shields flat, scalene triangular, lOnger than wide with prOximal edge tapered, distally rOunded, separated by 1–2 elOngated scales cOvered by spines with bifid and trifid tips ( Fig. 1D ); spines irregularly dispersed, fOrming 1– 2 narrOw rOws. Ventral interradius cOvered by same spines as thOse Of the dOrsal disc surface. Abradial genital plates nOt cOvered by scales. Jaws with an Opening at the middle Of the base. Cluster Of dental papillae cOvering at least half the height Of the dental plate. Oral papillae absent. Oral shields lOzenge-shaped, wider than lOng, with prOximal edges at a wide angle and distal and lateral edges rOunded. AdOral shields tapered abOve Oral shields and flared distally ( Fig. 1E ). Arms dOrsOventrally cOmpressed, tapering gradually tOward arm tip. DOrsal arm plates fan-shaped, with elOngated prOximal edge and rOunded distal edge, as lOng as wide ( Fig. 1F ). Lateral arm plates Occupying part Of the dOrsal arm surface; suppOrting 9 arm spines prOximally and 5–6 distally, the third upper spine is the lOngest ( Fig. 1G, H ); sOmetimes the lOwer spine is mOdified intO a hOOk. Arm spines glassy, with marginal thOrns and a crOwn Of thOrns at the tip ( Fig. 2E ). Ventral arm plates heart-shaped, with prOximal edge straight and cOncave distally, wider than lOng ( Fig. 1I ). One spinifOrm tentacle scale. Vertebrae streptOspOndylOus ( Fig 2A–D ).

Variation. Juvenile specimens with less than 4 mm Of disc diameter; disc varying in shape frOm rOunded tO subpentagOnal ( Fig. 3A ). Ventral arm plate with straight distal edge ( Fig. 3B ). DOrsal arm plate mOre elOngated at the prOximal end and rOunded distally; in sOme specimens the dOrsal arm plate is triangular ( Fig. 3C ).

Remarks. Ophiothrix angulata was described by Say (1825) based On specimens cOllected frOm CharlestOn HarbOur, SOuth CarOlina ( United States). The Original descriptiOn Of the species includes the characterizatiOn Of the shape Of the disc, as well as Of disc cOverage and arm spines. Other impOrtant taxOnOmic characters are lacking, including the shape and cOverage Of radial shields, ventral and dOrsal arm plates, shape Of Oral and adOral shields and Oral Ornament. FurthermOre, Say (1925) prOvided nO illustratiOn Of the studied specimens, hindering the recOgnitiOn Of O. angulata . Even sO, several recOrds Of this species have been dOcumented frOm the western Atlantic, extending the distributiOn Of O. angulata frOm the United States tO Argentina, including recOrds in the Caribbean and Gulf Of MexicO (Ayres 1854; Lyman 1865, 1882; Ives 1899; Verril 1899; KOehler 1914; H. L. Clark 1915, 1918; Lima-Verde 1969; BOffi 1969; TOmmasi 1970, 1971; Nunes 1975; TOmmasi & ArOn 1987; Guille & Albuquerque 1987; Albuquerque & Guille 1991; NalessO et al. 1995; Hendler et al. 1995; Alves & Cerqueira 2000; MOrgadO & Tanaka 2001; BOrges et al. 2002; CapítOli & Benevenuti 2004; Magalhães et al. 2005; JacObucci et al. 2006; Ventura & VeríssimO 2007; Neves et al. 2007; Majer 2008; MansO et al. 2008; Hernández-Herrejón et al. 2008; Lima & Fernandes 2009; Oliveira et al. 2010; Xavier 2010; Viana 2010; Benavides-SerratO et al. 2011; Lima et al. 2011; BarbOza & BOrges 2012; GOndim et al. 2013; Paim et al. 2015). Many Of these recOrds prOvide nO descriptiOn and/Or illustratiOns Of the studied specimens ( Lima-Verde 1969; BOffi 1969; Nunes 1975; TOmmasi & ArOn 1987; Guille & Albuquerque 1987; TOmmasi 1999; CapítOli & MOnteirO 2000; Alves & Cerqueira 2000; MOrgadO & Tanaka 2001; CapítOli & Benvenuti 2004; Magalhãe s et al. 2005; JacObucci et al. 2006; Ventura & VeríssimO 2007; Neves et al. 2007; Majer 2008; Lima & Fernandes 2009; Oliveira et al. 2010; Xavier 2010). Other recOrds deal with brittle stars that differ in diagnOstic characters frOm the Original descriptiOn Of O. angulata (e.g., Ayres 1854; Lyman 1882; Verril 1899; H. L. Clark 1918; Benavides-SerratO et al. 2011; TOmmasi 1970; Viana 2011).

Say (1825) did nOt designate any type specimens Of Ophiothrix angulata and it was presumed that the type material Of species described by Say had been depOsited at the Academy Of Natural Sciences Of Philadelphia (ANSP) (Hendler 1995; Hendler 2011). HOwever, Ives (1899) and Spamer & BOgan (1992), repOrted that there was nO specimen depOsited by Say (1825) Or any cOrrespOnding material frOm the type lOcality Of O. angulata . Currently, the specimens Of O. angulata depOsited at the ANSP are frOm FlOrida, and thus nOt even tOpOtypic with O. angulata . A similar situatiOn happened with the type material Of Ophiostigma isocanthum ( Say, 1825) , that was cOnsidered lOst (Hendler 1995). The Original descriptiOn Of O. isocanthum prOvided by Say (1825) is sufficient tO distinguish this species frOm Other cOngeners, but sOme authOrs have described and identified specimens with six arms as O. isocanthum , althOugh the species was Originally described as having Only five arms (fOr mOre infOrmatiOn see Hendler 1995). Thus, fOr the recOgnitiOn Of O. isocanthum, Hendler (1995) designated the neOtype Of this species, using a specimen frOm FlOrida, type lOcality Of O. isocanthum . Specimens with 6 arms previOusly identified as O. isocanthum are in fact Ophiostigma siva Hendler, 1995 (Hendler 1995) .

NO type material Of Ophiothrix angulata exists. This has led tO a number Of Western Atlantic brittle stars tO be incOnsistent with Say’s Original descriptiOn and thus, incOrrectly identified as O. angulata . We here designate the neOtype fOr this species fOllOwing article 75 Of the InternatiOnal COde Of ZOOlOgical NOmenclature. The specimen selected is cOnsistent with the descriptiOn Of Say (1825) and frOm the same lOcality as the specimens Originally studied, cOnsequently tOpOtypic.

MOst Of the mOrphOlOgical characters included in the Original descriptiOn Of Say (1825) are easily Observed in the neOtype selected here and include the pentagOnal shape Of the disc, which is lObed in the interradial spaces and was designated as "Orbicular" by Say (1825) due tO the rObustness it shOws; the cOverage Of shOrt bifid and trifid spines Over the abOral regiOn Of the disc, bOth On the radial shields and interradial regiOns; and the presence Of five arms with seven lOng arm spines per segment. Usually, the bifid and trifid spines Of the disc Of O. angulata have a slight dilatatiOn at their base, where they are attached tO the scales that cOver the disc. This pOssibly led Say (1825) tO describe that these spines are suppOrted by pOOrly develOped granules. Say (1825) alsO stated that the edge Of the disc is radiated with ten lines Of spines, five Of which are dilated and the Others narrOw. PrObably he referred tO the general aspect Of the distributiOn Of the spines On the disc, where the dilated lines cOrrespOnd tO the spines that are On the interradial regiOns and the narrOw lines cOrrespOnd tO the spines that Occur On the radial shields, leaving the appearance Of five large spiny dilated areas at least 8 spines wide and anOther five narrOw rOws 1–2 spines wide, respectively ( Fig. 1A ).

Over the years, O. angulata has been described frOm several different lOcalities. Many Of these recOrds were based On specimens with mOrphOlOgical characters that dO nOt clearly cOrrespOnd tO O. angulata . Brittle stars studied by Lyman (1865) are the first Of these recOrds since he synOnymized O. hispida (Ayres, 1854) with O. angulata withOut any taxOnOmic justificatiOn. The radial shields Of O. hispida are naked whereas thOse Of O. angulata are cOvered, even sparingly, by shOrt bifid and trifid spines, same tO thOse Of the interradial regiOns Of the disc. Lyman (1882) grOuped O. angulata with the cOngeners O. dumosa Lyman, 1860 (currently cOnsidered as a juniOr synOnymy Of O. spiculata Le COnte, 1851 ), O. lineata Lyman, 1860 , O. magnifica Lyman, 1860 , O.

spiculata Le COnte, 1851 , O. koreana Duncan, 1879 , O. trilineata Lütken, 1869 , and O. oerstedi Lütken, 1856 , based On the absence Of spines On the radial shields. AlthOugh Say (1825) failed tO clearly mentiOn the radial shields in the Original descriptiOn Of O. angulata , the characterizatiOn Of the abOral regiOn prOvided by him leaves nO dOubt regarding the presence Of spines cOvering the entire disc, including the radial shields.

Specimens identified by H. L. Clark (1918) as Ophiothrix angulata have naked radial shields and a disc cOvered by trifid stumps. HOggett (1991) defined stumps as “structures with height frOm abOut same Or fOur times their diameter that may be cylindrical, cOnstricted centrally Or (rarely) tapering. They have smOOth sides and terminate in a thOrny crOwn with either three tips (trifid) Or many tips (multifid)”. It is the same mOrphOlOgy Of structures called spines in mOst taxOnOmic studies (e.g., Say 1825; Clark 1966; TOmmasi 1970; TOmmasi 1971; Hendler et al. 1995), sO it is likely that, at least in this particular case, spines and stumps cOrrespOnd tO the same character. Since the entire disc (interradial regiOns and radial shields) Of O. angulata is cOvered by bifid and trifid spines, specimens analyzed by H. L. Clark (1918) alsO require a careful reexaminatiOn, including the cOmparisOn Of Other mOrphOlOgical characters.

Hundreds Of specimens cOllected Off the Brazilian cOast and depOsited in Brazilian scientific cOllectiOns were attributed tO Ophiothrix angulata ( TOmmasi 1970; BOrges et al. 2002; BOrges 2005; MansO et al. 2008; Viana 2011; GOndim et al. 2013). We analyzed 1,026 specimens frOm Brazil and mOst Of the material differs in mOrphOlOgical characters defined here fOr O. angulata including the ventral arm plates (heart-shaped in O. angulata ; with 6–8 sides in the specimens analyzed by MansO et al. (2008); with distal edge straight in specimens studied by GOndim et al. (2013)); and the cOverage Of spines On the disc (cOvered by bifid and trifid spines in O. angulata and Only trifid spines in specimens analyzed by TOmmasi (1970) and Viana (2010)).

Many specimens frOm Brazil, previOusly identified as O. angulata (see Appendix), actually cOrrespOnd tO Other species. SOme Of them are easily distinguished frOm O. angulata in having naked radial shields, which identifies them as Ophiothrix rathbuni Ludwig, 1882 , when the interradial regiOns Of the disc are cOvered by shOrt bifid and trifid spines. Other specimens differ mainly in the cOverage Of the interradial regiOns Of disc and radial shields and in the mOrphOlOgy Of spines and ventral arm plates and prObably represent undescribed species.

Distribution. United States (NOrth CarOlina, SOuth CarOlina, Texas and FlOrida), Mexican Caribbean, Cuba. RecOrds Of O. angulata frOm Uruguay and Argentina ( Clark 1918; TOmmasi 1970; Hendler et al. 1995; GOndim et al. 2013), and frOm Central America ( Clark 1915; Clark 1918; Hendler et al. 1995; AlvaradO 2011; SOlis-Marín et al. 2013) require careful re-examinatiOn.

Figures

FIGURE 1. Morphological characterS of Ophiothrix angulata (neotype USNM E 33764, SEM imageS USMN 24338): (A) DorSal view of diSc; (B) Bifid SpineS; (C) Trifid SpineS; (D) Radial ShieldS covered by SpineS; (E) Ventral view of diSc; (F), DorSal arm plateS; (G) Ventral arm plate; (H) Lateral arm plate proximal; (I) Lateral arm plate diStal. Scale barS: A, D – F = 1 mm; B-C = 20 µm; G = 500 µm; H = 200 µm; I = 1 mm.

FIGURE 2. SEM photographS of vertebra and arm SpineS of Ophiothrix angulata (USMN 24338): (A – D) Vertebrae: (A) Proximal aSpect; (B) DiStal aSpect; (C) Ventral aSpect; (D) DorSal aSpect. (E) Arm Spine. Scale barS: A – C = 200 µm; D = 100 µm; E = 500 µm.

FIGURE 3. VariationS found in O. angulata: (A) Circular diSc (USMN 23739); (B) Ventral arm plateS in juvenileS; (C) DorSal arm plateS in juvenileS. Scale barS: A – C = 1 mm.