Thyone pawsoni Tommasi, 1972

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 : 422-423

Thyone pawsoni Tommasi, 1972

( Figure 11 )

Thyone pawsoni Tommasi, 1972: 19 , figs 12–15; Pawson & Miller 1981: 397–398, figs 2d–e; Miller & Pawson 1984: 42, 34–35; Pawson et al. 2010: 30 , fig. 22; Martins et al. 2012: 3–5, figs 3–4; Prata et al. 2017: 8–9, figs 9g–i; Prata & Christoffersen 2017: 53, fig. 2c.

Material examined. Paraíba State, Brazil: 1 spec., Seixas Reef ( UFPB.ECH-1992); 1 spec., 703’50”S; 3447’19”W ( UFPB.ECH-2119); 1 spec., Seixas Beach ( UFPB.ECH-2266).

Type locality. Gulf of Venezuela, “Oregon 5679 Station, Venezuela ( Tommasi 1972).

Description. Specimen UFPB.ECH-1992. Fusiform body, slightly curved, tapered in the anterior end, 13 mm long and 5 mm in breadth in mid-body ( Fig. 11A ). Thin skin, rough. Color brown to whitish brown, tube feet yellowish and tentacles dark brown. In alcohol, whitish brown. Mouth terminal, anus slightly upturned. Tentacles 10, bushy, retracted, the two ventral ones smaller. Introvert short. Tube feet elongated, numerous, scattered over the body, arranged in double rows in the radii and several rows in the interradii, more abundant and bigger ventrally. Ten small papillae near the anus, in two circles of five papillae, and five anal teeth. Calcareous ring complex, with long posterior processes, forming a tube ( Fig. 11B ). Radial plates elongated, with processes tapering distally, divided into several pieces. Interradial plates elongated, slender, anterior end pointed and posterior concave. The interradial plate attached to radial up to about half length of the posterior processes. Madreporite rounded, stone canal slender. Polian vesicle single, oblong. Retractor muscles slender, reaching about 1/3 of the body. Longitudinal muscles thin. Respiratory trees short, branched. Gonads in single tuft, tubules short, unbranched. Body wall ossicles include tables of disc oval, with four holes and high two-pillared spire, ending in two to four teeth (90 μm long) ( Fig. 11D ). Tube feet include elongated supporting tables (110 µm long), with four large central holes and one or more small holes in the extremities, supporting plates with irregular holes and endplate (145 µm long). Introvert with tables (95 µm long) ( Fig. 11C ), rosettes (50 µm long) and plates (150 µm long). Tentacles include rosettes (50 µm long) and small rods (40 µm long), some with holes and sometimes prolongations.

Morphological variations. We analyzed three specimens, the size varied from 13– 8 mm long, 3–5 mm in breadth in mid-body. In young specimens the tegument is slightly rough, the tube feet are distributed in zigzag or double rows in the radii, with some in the interradii ( Fig. 11E ).

Geographical distribution. North Carolina, Florida, Eastern Gulf of Mexico, Venezuela ( Pawson et al. 2010) and Brazil (from Paraíba to Bahia coast). This species was found from 6–51 m deep ( Pawson et al. 2010; Martins et al. 2012). Here we found Thyone pawsoni from 1.5 to 10 m of depth, thus the bathymetry for this species now is 1.5–51 m of depth.

Remarks. Thyone pawsoni Tommasi, 1972 differs from other species in the West Atlantic, Thyone pseudofusus Deichmann, 1930 and Thyone crassidisca Pawson & Miller, 1981 , by having tables with thin and irregular margins, sometimes with more than four holes. Thyone pawsoni differs from Thyone florianoi Martins & Tavares, 2018 by irregular shape of the introvert table disc, table disc from body wall oval with handles and spire ending in four teeth. That species also differs from Thyone waltinhoi Martins & Souto, 2018 by oval table disc from body wall with handles and tall spire ending in four teeth. T. pawsoni differs from Thyone deichmannae Madsen, 1941 by absence of more than 10 holes in the table disc. According to Tommasi (1972), the tables shape and supporting rods is close to group fuscus species, being similar to the species of the Pacific Ocean.

Ecological note. The studied specimens were found associated with rhodoliths. According to Pawson et al. (2010) Thyone pawsoni can be found buried in silt-covered quartz sand and crushed shell sediments.

Figures

FIGURE 11. Thyone pawsoni Tommasi, 1972, UFPB.ECH-1992. A, external view; B, calcareous ring; C, table from introvert; D, tables from body wall; E, young specimen (UFPB.ECH-2119).