Sclerothyone reichi, Martins & Tavares, 2019

Martins, Luciana & Tavares, Marcos, 2019, Two new species of Sclerothyone from the southwestern Atlantic Ocean, with a key to genera and species of Sclerothyoninae (Holothuroidea: Dendrochirotida: Sclerodactylidae), Zootaxa 4658 (2), pp. 375-382 : 376-378

Sclerothyone reichi sp. nov.

( Fig. 1 , Table 1 )

Type material. REVIZEE, off coast of São Paulo, Brazil, 24°07’S, 44°42’W, 11.i. 1998, 101m, holotype 30 mm ( MZUSP 1644).

Etymology. This species is named in honor of Dr. Mike Reich in recognition for his contributions to the systematics of fossil Holothuroidea.

Diagnosis. Body U-shapped. Ten tentacles, ventral-most pair smaller. Tube feet scattered over body. Calcareous ring plates undivided; posterior processes subdivided and long, up to two times height of calcareous ring plate. Body wall with multilocular two pillared tables; tentacles with rods and introvert with two pillared tables and rosettes. Tube feet with only end plates.

Description. Body U-shaped, slightly upturned at both ends rough to touch ( Fig. 1a ). Ten dendritic tentacles, ventral pair reduced. Anal papillae present ( Fig. 1b ). Tube feet scattered throughout body. Radial and interradial plates of the calcareous ring of same length, entire, united at base only ( Fig. 1c ). Radial plates notched anteriorly for the passage of the radial nerves and radial canal; posterior processes subdivided into about 4 pieces. Interradial plates arrow-shaped, with an anterior depression. Longitudinal muscles thin, split into two in the anterior region of body; retractor muscle short, flat, attached between the muscular processes. Internal organs degraded (i.e., Polian vesicle, stone canal and madreporitenot not observed). Color brown in ethanol.

Ossicles: Body wall with two-pillared tables with circular disc, multiperforated by several holes and undulating margin; spire short, ending in a crown of teeth (80–100 μm long, Fig. 1 d–e). Introvert with two pillared tables with multiperforated, circular disc; undulating margin; spire short, ending in crown of teeth (40–60 μm long, ( Fig. 1f ) and rosettes 30–50 μm long ( Fig. 1g ). Tentacles with curved rods perforated at ends (60–80 μm long, Fig. 1h ). Tube feet with only end plates circular (up to 100 μm long, Fig. 1i )

Type locality. Brazil, off coast of São Paulo, 24°07’S, 44°42’W, 101 m.

Distribution. Known only from the type locality.

Remarks. Sclerothyone reichi sp. nov. superficially resembles S. velligera and S. unicolumnus , but differs from both species by having (1) multilocular tables in the body wall ( Fig. 1d, e ) and tentacles provided with rods only ( Fig. 1h ) (vs. four-holed tables in the body wall and tentacles with rods and plates in S. velligera ; and (2) unfused pillars in the body wall tables ( Fig. 1d, e ), and tables and rosettes in the introvert, ( Fig. 1f, g ) (vs. fused pillars in the body wall tables and no ossicles in the introvert in S. unicolumnus ).

Figures

FIGURE 1. Sclerothyone reichi sp. nov., holotype (MZUSP 1644). (A) lateral view of the body (mouth in red arrow and anus white arrow); (B) anal papillae (black arrow) and (C) calcareous ring; (D) body wall table in upper view (E) and lower view (F); introvert wall table in upper view; (G) rosette from introvert; (H) rod from tentacle and (I) end plate from tube feet. R, radial plate; IR, interradial plate; labels on calcareous ring follow Ludwig’s (1889–1892) scheme. Scale bars: A, 10mm; B–C, 1mm; D–E 50 μm; F–G, 30 μm; H, 50 μm.