Thyone crassidisca Miller & Pawson, 1981

Prata, Jéssica, Manso, Cynthia Lara De Castro & Christoffersen, Martin Lindsey, 2020, Dendrochirotida (Echinodermata: Holothuroidea) from the northeastern coast of Brazil, Zootaxa 4755 (3), pp. 401-453 : 419

Thyone crassidisca Miller & Pawson, 1981

( Figures 9–10 )

Thyone crassidisca Pawson & Miller, 1981: 400 , figs 1, 2b, 4a–d; Miller & Pawson 1984: 37, figs 29–30; Pawson et al. 2010: 27–28 , fig. 20; Martins & Tavares 2018: 534–535 , figs 1–2.

Material examined. Paraíba State, Brazil: 1 spec. 701’02”S; 3447’55”W ( UFPB.ECH-2113); 1 spec., 701’S; 3444’41”W ( UFPB.ECH-2115); 1 spec., 701’S; 3445’W ( UFPB.ECH-2021) .

Type locality. Florida, United States ( Pawson & Miller 1981).

Description. Specimen UFPB.ECH-2113. Fusiform body, curved, tapered in the ends, reaching 28 mm long, 5 mm in breadth in the middle of the body, posterior end slender ( Fig. 9A ). Skin thin, rough. Color whitish pink, with tentacles light brown, in alcohol whitish. Mouth and anus terminal, slightly upturned. Tentacles 10, bushy, two most ventral ones smaller. Introvert short. Tube feet arranged in double rows in the radii, present also in the interradii, covering the body; more abundant ventrally. Calcareous ring complex, tubular, with long posterior processes ( Fig. 9B ). Radial plates narrow with long processes posteriorly, and anterior end pointed. Posterior processes tapered distally, divided into small pieces. Interradial plates narrow, elongated, pointed anteriorly. Interradial plate attached to radial up to about half the length of the posterior processes. Madreporite rounded, stone canal long. Polian vesicle single, narrow, cylindrical. Retractor muscles short, reaching 1/3 of the body, longitudinal muscles slender. Respiratory trees with elongated branches. Gonads in single tuft, tubules short, unbranched. Body wall ossicles include tables of four holes, oval disc and robust two-pillared spire ending in a blunt spine (70 µm long) ( Figs. 9G , 10 D–E). Tube feet include numerous two-pillared supporting tables, with four central holes and one or more holes in the ends (110 µm long) ( Figs. 9H , 10 A–B), supporting plates ( Fig. 9I ) and endplates ( Fig. 10C ). Introvert with two-pillared tables of oval disc (60 µm long) with four central holes and numerous holes in each side ( Fig. 9D ), spire ending in one to four spines; and numerous rosettes (30 µm long). Tentacles with elongated rods (90 µm long) ( Fig. 9E ), rosettes (40 µm long) ( Fig. 9F ) and tables similar to those of the introvert ( Fig. 9C ).

Geographical distribution. North Carolina, Florida, eastern Gulf of Mexico ( Pawson et al. 2010) and Brazil (from Paraíba to São Paulo). This species was found between 4–45 m deep ( Pawson et al. 2010; Martins & Tavares 2018). Our material was found between 10–20 m deep.

Remarks. Thyone crassidisca differs from other species known for the West Atlantic, Thyone pseudofusus Deichmann, 1930 , Thyone deichmannae Madsen, 1941 , Thyone pawsoni Tommasi, 1972 and Thyone waltinhoi Martins & Souto, 2018 , by the body wall tables spire ending in a single blunt point. Thyone crassidisca differs from Thyone florianoi Martins & Tavares, 2018 by oval shape of the introvert table disc, oval with handles and knobbed margin of the body wall table disc, and also by the calcareous ring morphology.

Ecological notes. The specimens analyzed were found associated to rhodoliths. According to Pawson et al. (2010) Thyone crassidisca inhabits quartz sand and crushed shell bottoms.

Figures

FIGURE 9. Thyone crassidisca Pawson & Miller, 1981, UFPB.ECH-2113.A, external view; B, calcareous ring; C, tables from tentacles; D, tables from introvert; E, perforated rods from tentacles; F, rosette from tentacles; G, base of table from body wall; H, supporting tables from tube feet; I, supporting plate from tube feet.

FIGURE 10. Thyone crassidisca Pawson & Miller, 1981, UFPB.ECH-2113. A–B, supporting tables from tube feet; C, endplate; D–E, tables from body wall.