Euthyonidiella trita ( Sluiter, 1910 )

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 : 445

Euthyonidiella trita ( Sluiter, 1910)

( Figure 21 )

Thyone trita Sluiter, 1910: 339 , fig. e.

Phyllophorus tritus: Deichmann 1930: 147 , pl XVIII, figs 4–8.

Euthyonidiella trita: Hendler et al. 1995: 267 , figs 181g–h; Pawson et al. 2009: 1201; Pawson et al. 2010: 22 , fig. 14.

Material examined. 1 spec., Paraíba State, 703’50”S; 3447’19”W ( UFPB.ECH-2124).

Type locality. T ortugas, Florida, United States ( Deichmann 1930).

Description. Small body, barrel-shaped, about 1 cm in length ( Fig. 21A ). Soft skin. Color light pink. Mouth and anus terminal. Eighteen bushy, retracted tentacles. Introvert short. Tube feet numerous, covering the body, distributed in double rows in the radii, with several tube feet in the interradii. Calcareous ring complex, fragile, with moderate posterior processes ( Fig. 21B ). Radial plates rectangular, with posterior processes divided into some pieces. Interradial plates with the shape of an upside down heart, overlapping the radial plates. Madreporite rounded, stone canal long. Polian vesicle single. Retractor muscles thick. Longitudinal muscles thin. Respiratory trees with short branches. Gonad in single tuft, tubules branched, at least once. Ossicles of body wall include small tables (50 µm long) with four large holes, a few additional holes may be present ( Fig. 21 C–D); disc margin rounded to square, spire short, formed by two pillars, ending in some teeth. Tube feet have similar tables those from body wall, supporting plates ( Fig. 21E ) (80 µm long) and endplates (80 µm long) ( Fig. 21F ). Introvert with two-pillared tables of smooth disc with four large central holes and four smaller holes in the margin. Tentacles with rosettes and delicate rods, with a hole in both ends.

Geographical distribution. Florida, Virgin Islands, Antilles, Puerto Rico, Venezuela and Brazil ( Hendler et al. 1995, present study). Euthyonidiella trita was found in the State of Paraíba, associated with rhodoliths. It represents a new record for Brazilian coast. The species is found from the intertidal to depths of 4 m ( Pawson et al. 2010). Here, the species was found at a depth of 10 m, thus expanding its known bathymetric range.

Remarks. Deichmann (1930) mentions the presence of supporting rods on the tube feet of a specimen analyzed, a feature not recorded by Sluiter (1910). Deichmann (1930) attributed the absence of supporting rods in the other specimens to a possible loss of ossicles. The specimen analyzed here has elongated perforated plates in the tube feet, but supporting rods were not observed, it would need to observe more individuals to agree or disagree with that assumption of Deichmann (1930).

Ecological note. According to Pawson et al. (2010) Euthyonidiella trita occurs near the shoreline, under rocks, and in tidal pools. The specimen observed herein was found associated with rhodoliths.

Figures

FIGURE 21. Euthyonidiella trita (Sluiter, 1910), UFPB.ECH-2124.A, external view of animal; B, calcareous ring; C–D, tables from body wall; E, plates from tube feet; F, endplate.