Thyonella sabanillaensis ( Deichmann, 1930 )

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 : 78-79

Thyonella sabanillaensis ( Deichmann, 1930)

( Figs. 3–4 )

Thyone sabanillaensis Deichmann, 1930: 178 –179, plate 16, figs 4–9

Thyonacta sabanillaensis— Deichmann, 1941: 101

Thyonella sabanillaensis— Deichmann, 1954, 399

Thyonella sabanillaensis— Cherbonnier, 1957: 537 –540, fig. 1.

Thyonella sabanillaensis— Miller & Pawson, 1984: 25 –27, figs. 17, 18.

Material examined. Brazil: Espirito Santo, Piúma , 30. X. 1966, depth unknown, 1 spm, 80 mm (EH-IBZ/ UFRJ 144 ) . United States: Florida, 23. viii. 1971, 6 m, 1 spm, 150 mm ( USNM E22336) ; French Guiana, 6. xi.1955, 1 spm, 80 mm ( MNHN 3329 ) .

Type locality. Sabanilla , Colombia ( Deichmann, 1930) .

Distribution. Gulf of Mexico, Colombia, French Guiana (WoRMS, 2018) and Southwestern Brazil, Espirito Santo (present paper). Bathymetric range: currently known to inhabit quartz and shell bottoms, covered with algae mostly between 4 and 30 m ( Miller & Pawson, 1984).

Diagnosis. Tube feet papilliform distributed along the ambulacra in two rows and scattered in the interambulacra (mainly in the middle of body). Body wall ossicles include deep cups; four-holed knobbed buttons; knobbed and smooth plates. Introvert ossicles are rosettes. The tentacles hold rods.

Description. Body U-shaped, rough to touch ( Fig. 3A, D, E ). Color brownish in ethanol. Tube feet distributed along the ambulacra in two rows and scattered in the interambulacra (middle of body). Anal papillae present. Stone canal short and madreporite circular ( Fig. 3B ). Calcareous ring with short posterior processes; radial and interradial plates entire and equal in length; radial plates notched; interradial plates entire, narrowing anteriorly ( Fig. 3C, F ).

Body wall ossicles comprise four-holed knobbed buttons (40–80 µm long, Fig. 4A ); smooth perforated plates, irregular in outline (80–300 µm long, Fig. 4B ); perforated plates with spherical knobs (80–220 µm long, Fig. 4 C– D) and deep cups (40–60 µm long, Fig. 4 E–F). Introvert with buttons (20–60 µm long, Fig. 4G ). Tentacles with two types of perforated rods present: i) flat and elongated (200–400 µm long, Fig. 4H ) and ii) flat and irregular in outline (200–400 µm long, Fig. 4I ). Tube feet with curved supporting rods (200–300 µm long, Fig. 4J ) in papillae triangular plates (200–400 µm long Fig. 4K ) end plate absent. Anal region with large perforated plates (500–700 µm long Fig. 4L ).

Remarks. Thyonella sabanillaensis was previously known only from the Gulf of Mexico to French Guiana and it is reported here for the first time from the Southwestern Atlantic ( Brazil, Espírito Santo ~21° S). The specimens herein identified as T. sabanillaensis agree with the description provided by Deichmann (1930) except in the composition of the introvert ossicles. Deichmann (1930) did not comment on the composition of introvert ossicles. However, Deichmann (1954) described rosettes in the introvert. In the material examined, rosettes have not been not found, but buttons are present.

The differences observed between specimens from Brazil and French Guiana were in relation to the morphology of the calcareous ring. In the specimen from French Guiana, plates of the calcareous ring are slightly broader ( Fig. 3F ) than plates from the material examined herein ( Fig. 3 C ). No significant differences were observed between specimens from Brazil and Florida.

Figures

FIGURE 3. Thyonella sabanillaensis (Deichmann, 1930) (EH-IBZ/UFRJ 144). (A) Specimen preserved in ethanol; (B) madreporite (black arrow); (C) calcareous ring; (D) specimen preserved in ethanol (USNM 22336); (E) specimen preserved in ethanol (MNHN 3329) and (F) calcareous ring from (MNHN 3329). R, radial plate; IR, interradial plate. Scale bars: A, 40 mm; C, 10 µm; D 50 mm; E, 40 mm; F, 10 mm.

FIGURE 4. Thyonella sabanillaensis (Deichmann, 1930) (EH-IBZ/UFRJ 144). SEM images of the ossicles: (A) four-holed button from body wall; (B) smooth plate from body wall; (C–D) knobbed plate from body wall; cup in dorsal (E) and ventral (F) view; (G) button from introvert, (H–I) rods from tentacles and (J) rods from tube feet; (K) triangular plate from body papillae; (L) anal plate. Scale bars: A, 50 µm; B, 100 µm; C, 40 µm; D, 100 µm; E–G, 20 µm; H–L, 100 µm