Trachythyone crassipeda Cherbonnier 1961

Trachythyone crassipeda Cherbonnier, 1961

(Figure 6)

Trachythyone crassipeda Cherbonnier, 1961: 613–615, figs 2a–r; Tommasi 1969: 14, fig. 21; Mondin 1973: 9, fig. 4; Miranda et al. 2015: 116, figs 5e–f; Bueno et al. 2018: 196–198, fig. 30.

Material examined. Bahia State, Brazil: 1 spec., Ponta de Aratuba, Itaparica (UFPB.ECH-2093); 1 spec., Itapo Beach, Salvador (UFPB.ECH-2032); 1 spec., Penha Beach, Vera Cruz, Island of Itaparica (UFPB.ECH-2026); 4 spec., Tarra Reef, Prado (EQMN-1688).

Type locality. Bahia, Brazil (Cherbonnier 1961).

Description. Specimen UFPB.ECH-2032. Small barrel-shaped body, about 4 cm long, 2.5 cm in breadth at mid-body (Fig. 6A). Soft skin, color light brown, with yellowish brown stripes in the radii. Mouth and anus slightly upturned. Anus with five small papillae and five anal teeth present. Introvert short. Tentacles 10, bushy, thick, equal in size. Tube feet short, numerous, distributed in double rows in radii, and several rows in the interradii, covering the body, being more abundant ventrally. Calcareous ring simple, large, formed by 10 sub-equal triangular shaped plates, without posterior processes (Fig. 6B). Madreporite rounded, brain-like; stone canal spiraled. Polian vesicle single, large. Retractor muscles thick, about half body length. Longitudinal muscles thin. Respiratory trees well branched, about 3/4 of the body length from posterior end. Gonad in single tuft, with tubules very elongate, unbranched. Body wall ossicles consist of plates, elongated to rounded, about six or more holes, two central ones bigger (200 μm long) (Fig. 6J); and shallow baskets (60 μm long) with four holes, and 10–12 spines in the margin (Fig. 6K). Posterior end includes also irregular, oblong to rectangular perforated plates (Fig. 6L), some with a dense second layer of calcite, similar to scales (200 μm long). Tube feet have elongated rods (200 μm long), with small holes (Fig. 6O), irregular supporting plates with numerous holes (150 μm long) (Fig. 6M) and endplate (150 μm long) (Fig. 6N). Introvert with rosettes (60 μm long) (Fig. 6I), baskets, some knobbed (50 μm long) (Fig. 6G), and elongated plates (150 μm long) (Fig. 6H). Tentacles include perforated rods (200 μm long) (Fig. 6F), irregular plates (80 μm long) (Fig. 6E), irregular baskets (40 μm long) (Fig. 6D), and large to small rosettes (60 μm long) (Fig. 6C).

Morphological variations. A total of seven specimens were analyzed, the size varied from 40 mm long, 18–25 mm in breadth in mid-body, 8.5–15 mm breadth in anterior end, and 10–18 mm breadth in posterior end. The color varied from brown to grayish brown, with yellowish stripes in the radial areas. Dark brown spots can also occur over the radii, tube feet and tentacles.

Geographical distribution. Brazil, from Bahia to Paran (Bueno et al. 2018). It is found in the intertidal zone (Mondin 1973). The material analyzed was found in tide pools, near coralline rocks.

Remarks. According to Cherbonnier (1961) Trachythyone crassipeda has affinities with Trachythyone parva (Ludwig, 1875), from the Chilean coast, but it differs in the arrangement of the ventral tube feet, uniform size of the tentacles, absence of “X-shaped ossicles and presence of plates.