Thyonella pervicax ( Théel, 1886 )

Martins, Luciana, 2018, Taxonomy of the genus Thyonella (Holothuroidea: Dendrochirotida), with mention of the first record of T. sabanillaensis from the southwestern Atlantic Ocean, Zootaxa 4527 (1), pp. 75-86 : 76-77

Thyonella pervicax ( Théel, 1886)

( Figs. 1–2 )

Thyone pervicax Théel, 1886: 93 –94, plate V; fig. 9; plate XII, fig 3

Thyonella pervicax— Deichmann, 1954: 398 –399, fig. 67, 12–20

Thyonella pervicax— Miller & Pawson, 1984: 23, figs 15, 16

Thyonella pervicax— Hendler et al., 1995: 264 –265, plate 144, figs. 179 E–H

Thyonella pervicax— Pawson et al., 2010: 20 –22, figs 6B, 13.

Material examined. Thyonella pervicax . Brazil: São Paulo, ii.1990, depth unknown, 1 spm, 30 mm ( MZUSP 1350 ) ; Espírito Santo, Vitória , depth unknown, 1 spm, 30 mm ( MZUSP 1643 ) ; United States: Florida, 25. iv. 1983, 27 m, 2 spms, 50–60 mm ( USNM E33170 ) ; 25.iv. 1983, 64 m, 2 spms, 40–50 mm ( USNM E33164 ) .

Type locality. Off Bahia, 13° 06’; 38° 07’ ( Théel, 1886) .

Distribution. From Massachusetts to Brazil, Bahia (São Paulo, Brazil present paper). Inhabits quartz and shell bottoms, covered with algae and seagrass mostly between 6 and 70 m ( Miller & Pawson, 1984; Hendler et al., 1995).

Diagnosis. (amended from Théel, 1886)

Tube feet scattered over body and modified into low warts. Body wall ossicles include shallow cups, fourholed to multilocular; four-holed knobbed buttons and knobbed perforated plates. Introvert ossicles buttons, tentacles with rods.

Description. Body U-shaped, slightly upturned at both ends and rough to touch; color whitish or brownish in ethanol ( Fig. 1A ). Tube feet in double rows in the ambulacra and scattered over interambulacra. Anal papillae present ( Fig. 1B ). Stone canal short, madreporite bean-shaped; Polian vesicle single ( Fig. 1C ). Calcareous ring with short posterior processes; radial and interradial plates entire and equal in length; radial plates notched; interradial plates entire and narrowing anteriorly ( Fig. 1D ).

Body wall ossicles four holed-buttons strongly knobbed (50–100 µm long, Fig. 2A ); four-holed to multilocular shallow cups (30–50 µm long, Fig. 2 B–C); knobbed perforated plates with triangular knobs (340–600 µm long, Fig. 2D ); Introvert with buttons undulating at margins and slightly knobbed (50–60 µm long, Fig. 2E ). In the tentacles, three types of perforated rods: i) flattened and elongated (300–400 µm long, Fig. 2F ); ii) flattened and irregular in outline, often two-armed (200–300 µm long, Fig. 2G ) and iii) curved rods at base of tentacles (100–300 µm long, Fig. 2H ). In the tube feet, supporting rods curved (100–200 µm long, Fig 2I ); end plate absent.

Remarks. Thyonella pervicax was described by Théel (1886) based on a single specimen from Bahia, Brazil. The specimens herein described as T. pervicax concurs with the description provided by Théel (1886) except in the arrangement of tube feet. According to Théel (1886), the tube feet in T. pervicax were not arranged in two rows. The specimens studied, however, show a double row of tube feet ( Fig. 1A ). The other difference from Théel's (1886) specimen and those under study here, relates to the cup shaped ossicles reported by Théel as four-holed cups are more common than multiperforated cups. However, it was found that multilocular cups are more common than four-holed cups.

Some characters of T. pervicax , such as the introvert and tentacle ossicles were not described from the single holotype.

Deichmann (1930, 1954) reported the presence of buttons in the introvert and rods in the tentacles were described. Miller & Pawson (1984), however, noted that buttons and cups are present in the introvert. In all analyzed specimens, no cups were found in the introvert, and the presence of these ossicles may be probably due to contamination or possibly geographic variation

Figures

FIGURE 1. Thyonella pervicax (Théel, 1886) (MZUSP 1350). (A) Specimen preserved in ethanol above (MZUSP 1350) and below (USNM E33170), (B) anal papillae (black arrow), (C) Polian vesicle, stone canal and madreporite (red, black and white arrows, respectively) and (D) calcareous ring. R, radial plate; IR, interradial plate. Scale bars: A, 30 mm; B, 400 µm, D, 200 µm.

FIGURE 2. Thyonella pervicax (Théel, 1886) (MZUSP 1350). SEM images of the ossicles: (A) four-holed button from body wall, (B) cups in lateral and (C) ventral view, (D) knobbed plate from body wall, (E) button from introvert, (F–H) rods from tentacles and (I) supporting rods from tube feet. Scale bars: A–C, 50 µm; D, 200 µm; E, 30 µm; F–H, 200 µm; I, 100 µm