Scoliodota theelii Heding, 1928

Yamana, Yusuke, Yamamoto, Masaki, Ota, Yuzo, Kohtsuka, Hisanori, Omori, Akihito, Iwasaki, Kazuma & Setiamarga, Davin H. E., 2022, Partial redescriptions of three holothurians with “ hook papillae ” (Apodida Chiridotidae): Taeniogyrus japonicus (Marenzeller, 1882), T. dendyi (Mortensen 1925), Scoliorhapis theelii (Heding, 1928), Zootaxa 5138 (4), pp. 351-387 : 374-376

Scoliodota theelii Heding, 1928

( Figs 13 , 14 )

Chirodota japonica Marenzeller, 1882 : Théel 1886: 17, Pl. 2. fig. 3.

Scoliodota japonica ( Marenzeller, 1882) : Clark 1908: 30, pl. 7. fig. 5.

Scoliodota theelii Heding, 1928: 319–322 , Fig. 69.

Scoliorhapis theelii ( Heding, 1928) : Clark 1946: 461; Rowe and Gates 1995: 267: O’Loughlin and VandenSpiegel 2010: 76–78, Table 3 .

Scoliorhapis theeli: Rowe et al. 2017: 481 .

Comparative material. Two syntypes ZMUC-HOL-220 (one male and one female), collected by Dr.Th. Mortensen, on Oct. 8, 1914, from 6–9 m deep off Port Jackson , Australia. These were dissected by Mortensen or Heding, and one specimen was labeled as “ ♂ ” (length 45 mm, width 3–7 mm) and the other as “ ♀ ” (length 32 mm, width 4–8 mm) .

Description. Preserved color pale grey to ocher yellow. Numerous “hook papillae” in all inter-radii ( Fig. 13 ), along length of body. Color of hook papillae same as adjacent skin. Minute verrucae of hook papillae densely distributing anterior skin surface ( Fig. 13 A').

Ten stout tentacles with 14 digits ( Table 3 ); distal digit pair largest. Sensory cups absent. Both specimens were dissected and calcareous ring removed, however, it can be observed that traces of large retractor muscles or ligaments which combined calcareous ring with longitudinal muscles were remaining. Calcareous ring inclined toward ventral side, composed of five thick radial and five thick inter-radial plates ( Fig. 13C ). All plates with a posterior depression, approximately rectangular on ventral and triangular on dorsal surface. Trapezoid anterior projection with central notch in RI, and low triangle anterior projection in IR5, no perforation present. Other eight plates have an anterior projection on near dorsal end. Polian vesicle single, in RI. Single stone canal reported was not detected, apparently removed. The intestine without loop. Gonadal tubules on both sides of anterior dorsal mesentery, growing in clusters, branched. One sparse row of ciliated funnels situated in right side of dorsal mesentery IR5, another on left dorsolateral inter-radius IR3, along left ventrolateral longitudinal muscle RII. Funnels short (approximately 0.10 mm long), with short stalk.

Antero-dorsal body wall with sigmoid-hooks only in both specimens ( Figs 13 , 14 ). Sigmoid-hooks without spinelets ( Fig. 14 ) 97–137 µm and 105–134 µm, in anterior body of “ ♂ ” and “ ♀ ” specimens, respectively ( Table 6).

Tentacles ossicles curved, distally expanded rods, occasionally with minute, inwardly directed distal teeth ( Fig. 13 ), 32–59 µm long in “ ♀ ” specimen ( Table 6).

Remarks. The present observations agree with Théel’s (1886) and Heding’s (1928) observations. However, we documented another band of funnels in the left dorsolateral inter-radius, that were not previously reported ( Heding 1928). Although the presence of retractor organ itself was not observed in the present study, Heding (1928) had reported as follow: retractor muscles are large united with the body-wall by a mesentery-like tissue ( Heding, 1928, p321). In the present study, the anterior projection of the medioventral piece of the calcareous ring in the female specimen ( Heding 1928) was not observed, but the remaining of the retractor organ was observed. Consequently, it will be inferred that this apodid sea cucumber also with retractable tentacle as well as other two congeners.

Distribution. Port Jackson, Australia, from 6–9 m deep ( Heding 1928) and 2–10 fathoms (ca. 3.6–18.3 m) ( Théel 1886): Port Jackson, NSW; 5.4–9 m ( Heding 1928). NE coast, Great Barrier Reef, SE coast, Bass Strait, Tasmanian coast, W coast, QLD, NSW, TAS, WA; Port Denison to Heron Island, QLD and Port Jackson, NSW to SE TAS, and Rottnest Island; depth 0-5 m; temperate, (sub-tropical), endemic; benthic, inshore, detritus feeder, deposit feeder ( Clark 1946; Rowe and Gates 1995). Endemic Australian, relatively uncommon; shallow temperate to subtropical waters from Western Australia to Victoria and Tasmania and north through New South Wales to northeastern Australia ( Rowe and Gates 1995; Rowe et al. 2017). Rottnest Island: Nancy Cove and Thomson Bay; 3-7.5 m; sand ( Marsh and Pawson 1993).

Figures

FIG. 13. Scoliodota theelii Heding, two syntypes of the Zoological Museum of University of Copenhagen (ZMUC). A–C, lateral views of the “♀” specimen of the ZMUC-HOL-220 (A); the “♂” specimen of the ZMUC-HOL-220 (B); enlarged photo of its anterior body surface (B') and calcareous ring of the “♂” specimen of the ZMUC-HOL-220 (C), anterior left, dorsal upper. D and E, microphotograph of skin containing ossicles in anterior dorsal side of the “♀” specimen of the ZMUC-HOL-220 (D); and the “♂” specimen of the ZMUC-HOL-220 (E). Abbreviations: ad, anterior dorsal; ca, calcareous ring; po, Polian vesicle; sh, sigmoid-hook ossicle; te, tentacles.

FIG. 14. Scoliodota theelii Heding, 1928, two syntypes of the Zoological Museum of University of Copenhagen (ZMUC).A, B, ossicles from anterior dorsal body wall of the “♂” specimen of the ZMUC-HOL-220 (A); and ossicles from anterior dorsal body wall and tentacle of the “♀” specimen of the ZMUC-HOL-220 (B). Abbreviations: ad, anterior dorsal; te, tentacle.