Pseudothyone belli ( Ludwig, 1887 )

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 : 432-435

Pseudothyone belli ( Ludwig, 1887)

( Figure 16 )

Thyone belli Ludwig, 1887: 21 , pl. I, fig. 6; Deichmann 1930: 176–177, figs 1–6; Brito 1962: 4; Tommasi 1969: 13; Tommasi 1971: 2.

Thyone micropuntacta: Sluiter, 1910: 338 , fig. d; Deichmann 1930: 171, figs 14–18.

Pseudothyone belli: Panning 1949: 456 ; Miller & Pawson 1984: 27, figs 19–20; Hendler et al. 1995: 268, figs 180a–c.

Material examined. Paraíba State, Brazil: 4 spec. 659’01”S; 3447’23”W ( UFPB.ECH-2095); 8 spec., João Pessoa, 701’00”S; 3446’02”W ( UFPB.ECH-146); 1 spec., 701’02”S; 3447’35”W ( UFPB.ECH-2097); 1 spec., 703’18”S; 3445’10”W ( UFPB.ECH-2098); 14 spec., João Pessoa, 703’50”S; 3447’19”W ( UFPB.ECH-144); 1 spec., João Pessoa ( UFPB.ECH-2099); 1 spec., Ponta do Cabo Branco , João Pessoa ( UFPB.ECH-2043); 10 spec., 0704’24.4”S; 3447’49”W ( UFPB.ECH-2096); 1 spec., 0704’26”S; 3449’51”W, ( UFPB.ECH-2044); 1 spec., 706’59”S; 3446’04”W ( UFPB.ECH-2016); 1 spec., Atolzinho, Bessa Beach, João Pessoa ( UFPB.ECH-1990); 1 spec., Reefs in front of Iate Club of Paraíba, Bessa Beach ( UFPB.ECH-1959), 2 spec., Reefs in front of Iate Club of Paraíba, Bessa Beach ( UFPB.ECH-2094).

Type locality. Abrolhos, Bahia, Brazil ( Deichmann 1930).

Description. Specimen UFPB.ECH-2097. Sub-cylindrical body, elongated ( Fig. 16A ), about 1 cm long, with 5 mm in breadth in mid-body. Rough skin, due to the large number of ossicles. Color light brown to white, with few brown spots in life, whitish in alcohol. Mouth and anus terminal. Tentacles 10, bushy, the two most ventral reduced. Introvert short, without tube feet. Tube feet distributed in two rows in the radii, with numerous tube feet also in the interradii, more abundant ventrally. Calcareous ring complex, fragile, with long posterior processes ( Fig. 16B ). Radial plates slender, with posterior processes tapered and anterior end with a short bifurcation. Interradial plates slender, short, about 1/2 the length of the radial plate, with anterior margin pointed. Madreporite cotyledon shaped, stone canal elongated; Polian vesicle small, single. Retractor muscles thick, about 1/3 of body length. Longitudinal muscles thin. Respiratory trees little branched. Gonad in single tuft, tubules short, unbranched. Body wall ossicles consist of elongated knobbed buttons of four to six central holes (100 µm long) ( Figs. 16 G–H), large knobbed perforated plates, smooth margin and numerous holes, the central ones bigger ( Fig. 16I ). Tube feet include elongated supporting tables with small holes in the ends, formed by three short pillars ending in three teeth (115 µm long) ( Fig. 16J ), plates with two large central holes and a few marginal holes (90 µm long) ( Fig. 16K ), and large endplates (95 µm long). Introvert includes elongated to rounded tables (Figs. 146D–E) and small rosettes ( Fig. 16F ). Tentacles with rosettes ( Fig. 16C ).

Morphological variations. A total of 48 specimens were analyzed. The size varied from 7–21 mm long, and 3–6 mm in breadth in mid-body, 2–3 mm in breadth in anterior end, and 1.5–2 mm in breadth in posterior end. Juvenile specimens present tube feet only in the radii and show gray spots on the body ( Fig. 16L ).

Geographical distribution. Bermudas, Gulf of Mexico, Antilles, Panama, Puerto Rico, and Brazil ( Pawson et al. 2010). In Brazil from Paraíba to Bahia in Northeast coast. The species was recorded in depths down to 70 m ( Hendler et al. 1995). The specimens analyzed were found between 10–15 m depth.

Remarks. This is the only species of the genus Pseudothyone recorded from the West Atlantic. The species Thyone micropuntacta Sluiter, 1910 was referred to as a synonym of juvenile P. belli .

Ecological notes. The specimens observed were found associated with rhodoliths, phytal of Halimeda opuntia and Sargassum sp. The specimens from rhodoliths were found co-occurring with Pentamera paraibanensis Prata & Christoffersen, 2016 and Thyone pseudofusus Deichmann, 1930 . These specimens also showed a loss of the calcareous ring with their tentacles and structures linked to the ring, such as the gonad and retractor muscles. This is a defense tactic for small species.

Figures

FIGURE 16. Pseudothyone belli (Ludwig, 1887), UFPB.ECH-2097. A, external view of animal; B, calcareous ring; C, rosette from tentacles; D–E, elongated to rounded tables from introvert; F, rosettes from introvert; G–H, knobbed buttons from body wall; I, large knobbed plate from body wall; J, supporting table from tube feet; K, supporting plate from tube feet; L, external view of a young specimen.