Ophiothrix suensoni Lütken, 1856

Santana, Alisson, Manso, Cynthia L. C., Almeida, Ana C. S. & Alves, Orane F. S., 2020, Taxonomic review of Ophiothrix Müller & Troschel, 1840 (Echinodermata Ophiuroidea) from Brazil, with the description of four new species, Zootaxa 4808 (1), pp. 51-78 : 55-57

Ophiothrix suensoni Lütken, 1856

( Figs. 3 , 4 )

Ophiothrix suensoni Lütken, 1856: 1–19 . [Antilles, Caribbean]

Ophiothrix suensoni: Rathbun 1879: 153 . [Rio de Janeiro, Brazil]

Ophiothrix (Acanthophiothrix) suensoni: Tommasi 1970: 63 . [Florida, United States]

Ophiothrix suensoni: Hendler et al. 1995: 187–188 , fig. 99. [Florida and Texas, United States; Mexico; Bermudas]

Ophiothrix (Acanthophiothrix) suensoni: Pomory, 2003: 97–98 , fig. 47. [Texas, United States]

Ophiothrix suensoni: Benavides-Serrato et al. 2011: 308 . [ Colombia]

Material examined. USMN 8913 (01 specimen), Bacia de Campos , Rio de Janeiro, Brazil, 24º00’S, 40º00’W, coll. 1876 by T. Lyman. Additional material . USMN E 13642 (03 specimens), Florida, United States, 30º38’N, 80º85’W, 26 m, coll. II/1980 ; ZUEC 01892 (01 specimen), Carrie Bow Bay , Belize, 18–55 m, coll. 13/ III /1989 by G. Hendler.

Type locality. Antilles, Caribbean.

Diagnosis (modified from Benavides-Serrato et al. 2011). Disc (interradial regions) covered by long needleshaped spines and with tubercle-like spines between the long spines; radial shields naked; ventral arm plates square, with depressed distal edge.

Description. A specimen with 9.34 mm of disc diameter. Five arms dorsoventrally compressed. Disc circular, excavated between the arms; interradial regions covered by small, rounded and imbricated scales that support long needle-shaped spines; short, smooth and tapering spines among the long spines. Disc coverage sparse. Central primary plates and radial primary plates not visible ( Fig. 3A ). Scales at the lateral disc edge bear short and smooth spines, similar to those among the long needle-shaped spines on the disc ( Fig. 3C ). Radial shields long, flat, naked, scalene triangular, wider than long, proximally tapered, separated by 1–2 scales and distally rounded, in contact ( Fig. 3B ). Ventral interradius covered only by scales, without spines. Genital plates at the base of arms. Oral shields lozenge-shaped, wider than long, distal edge straight and proximal and lateral rounded. Madreporite wider than other oral shields and oval in shape. Adoral shields triangular or without a distinct shape, in contact proximally or separated by oral shields. Cluster of dental papillae on the apex of the jaw, covering at least half the height of the dental plate. Infradental papilla and oral papillae absent. Oral tentacle pore visible ( Fig. 3D ). Dorsal arm plates flabeliform, as wide as long ( Fig. 3E ). Ventral arm plates squared, with concave distal and lateral edges ( Fig. 3F ). Lateral arm plate occupying part of the dorsal surface of the arm, bearing 6-8 needle-shaped glassy spines, laterally smooth and with crown of spines at the apex; the ventral arm spine can be modified into a hook. One spiniform tentacle scale.

Variations. The shape of the disc varies in shape from pentagonal to circular in juvenile specimens ( Figs. 4A, B ). In some specimens, the spines on the disc are supported by thick scales that resembles granules. The needleshaped spines vary in length from short (about 1,3 mm long) in the interradial regions of the disc to very long in the center of the disc (up to 2,6 mm long).

Color patterns. The external coloration is variable, including purple, orange, pink ( Benavides-Serrato et al. 2011) and white specimens (present study). Sometimes longitudinal black stripes that extend from the radial shields to the distal margin of the arms are seen.

Remarks. The first and unique record of O. suensoni for the Brazilian coast was made by Rathbun (1879) based on specimens from Rio de Janeiro State. This specimen was analyzed here (USMN 8913) and show all diagnostic characters of O. suensoni . However, because of its bad preservation condition, we were not able to illustrate it. Barboza & Borges (2012) listed O. suensoni referring to specimens analyzed by Tommasi (1970) on the checklist of Ophiuroidea from Brazil. However, these specimens are from Florida and not from Brazil (see Tommasi 1970).

The main character to distinguish O. suensoni from other congeners with naked radial shields are the long needle-shaped spines interspersed by tubercle-like spines that cover the interradial regions of the disc ( Figs. 3 A–C, 4A, B).

Distribution. Western Atlantic: Florida and Texas ( United States), Gulf of Mexico ( Mexico), Bermudas, Antilles, Central America, Colombia, Venezuela and Brazil (Rio de Janeiro) ( Lütken 1856; Rathbun 1879; Hendler et al. 1995; Pomory 2003; Benavides-Serrato et al. 2011).

Figures

FIGURE 3. Ophiothrix suensoni: A, Dorsal view of disc showing long needle-shaped spines; B, detail of naked radial shields; C, detail of the edge of the disc showing short conical spines; D, oral frame; E, dorsal arm plates; F, ventral arm plates with lower arm spines modified in a hook (ZUEC 01892, Carrie Bow Bay, Belize A–D, F; USMN 19642, Florida, United States, E). Scale bars: A = 2 mm; B–F = 1 mm.

FIGURE 4. Differences of the shape of the disc between specimens of Ophiothrix suensoni: A, disc pentagonal; B, disc circular (USMN 19642, Florida, United States). Scale bars: 1 mm.