Scoliorhapis H. L. Clark 1946

Genus Scoliorhapis H.L. Clark, 1946

Scoliorhapis H. L. Clark, 1946: 461.—Rowe in Rowe and Gates, 1995: 267.— Smirnov, 1998: 519.— O’Loughlin and VandenSpiegel, 2010: 76.— Solis-Marin et al., 2014: 324.

Scoliodotella Oguro, 1961: 2.

Scoliodota Heding, 1928: 319 (junior homonym of Scoliodota H. L. Clark, 1908).

Diagnosis (after H. L. Clark, 1946 and O’Loughlin and VandenSpiegel, 2010, emended here).

Taeniogyrinae with 10 or 12 peltato-digitate tentacles, each with up to 8 pairs of digits. Single polian vesicle. Intestine without loop. Ossicles: body wall ossicles sigmoid hooks or two-pointed sigmoids only; sigmoid hooks and two-pointed sigmoids scattered but some clastered or aligned; wheels lacking in body wall; tentacle ossicles bracket-shaped or rods.

Type species. Scoliodota theelii Heding, 1928 (Eastern Australia, from Port Denison (North Queensland) till Port Davis Creek (Spencer Gulf, South Australia), Tasmania, Rottnest Is. (Western Australia), 0–5 m..

Other species. Scoliorhapis biopearli O’Loughlin and VandenSpiegel, 2010 (Scotia Sea, South Shetland Is., 1544 m); Scoliorhapis dianthus Solis-Marin et al., 2014 (Sea of Japan, Sado Is., 0.5–1 m); Scoliodota lindbergi Djakonov in Djakonov, Baranova and Saveleva, 1958 (North Japan Sea, Hokkaido, South Sakhalin, South Kurile Is, 0–65 m); Scoliorhapis massini O’Loughlin and VandenSpiegel, 2010 (Scotia Sea, Shag Rocks, 206 m; Falkland Islands, 118 m,); Scoliorhapis stepanovi sp. nov. (East Kamchatka, Avacha Bay, North Kuril Is., Paramushir Is., Middle Kurile Is., Matua Is., 10–24 m).

Remarks. H. L. Clark (1908) established the new monotypic genus Scoliodota for Chiridota japonica v. Marenzeller, 1881, described from Japan. According to v. Marenzeller (1881) description this species had only sigmoid hooks that were clustered in the papillae. Clark used the following characters to diagnose the new genus Scoliodota: “Tentacles 10. Digits 10 or more. Wheels wanting; calcareous particles sigmoid bodies only, commonly arranged in groups” (Clark, 1908: 125). Clark had no Japanese specimens on hand but following Théel (1886) assigned a specimen from Port Jackson, Australia that he had studied to this species: “There is a single specimen in the collection, one of those taken by the "Challenger" at Port Jackson, New South Wales, and already described by Théel. There can be no doubt that wheels are entirely wanting” (Clark, 1908: 30).

Ohshima (1913, 1914) studied synaptids from Misaki, near the type locality of Chiridota japonica v. Marenzeller, 1881, and found that synaptids with sigmoid hooks clustered in papillae as described for Scoliodota japonica (v. Marenzeller, 1881) also had wheels in the body wall, which “…are extremely infrequent, though near the base of tentacles they can be found without much difficulty” (Ohshima, 1914: 480; see drawings of the wheels in Ohshima, 1913: 260, text-figs. C, D; pl. 6, fig. 1). Ohshima thus concluded that this species could be transferred to Trochodota and Scoliodota Clark, 1908 thus was synonymized with Trochodota Ludwig, 1892. Clark agreed (Oguro, 1961), and the final list of holothurians collected by the “Albatross” in the Northwestern Pacific during the summer 1906 included Trochodota japonica (v. Marenzeller, 1881) (Ohshima, 1919: 149).

Clark (1921: 164) continued the synonymization of his genus Scoliodota with Trochodota.

Rowe (1976) transferred Trochodota japonica to Taeniogyrus Semper, 1867, so Scoliodota became a synonym of Taeniogyrus.

Heding (1928) studied specimens from Port Jackson, Australia, determined earlier as Chiridota / Scoliodota japonica by Théel (1886) and Clark (1908), but found no wheels in the body wall. He described these as a new species, Scoliodota theeli, characterized by the presence in the body wall of sigmoid hooks only, clustered in body wall papillae. Heding resurrected Scoliodota Clark and designated S. theeli as the type species of the restored genus. Heding’s (1928: 319) diagnosis was: “Tentacles ten, peltated, digitate. Wheels wanting; calcareous deposits in the skin sigmoid bodies only. In the tentacles rods may occur. Calcareous ring bilaterally symmetrical. Polian vesicle and stone-canal single”. He did not refer to the arrangement of the sigmoid hooks, whether scattered or clustered. Because Scoliodota was already typified through monotypy by Clark (1908), Heding’s type designation was not valid. Clark (1946) suggested a new genus name Scoliorhapis for Scoliodota sensu Heding, 1928 (non Clark, 1908) with the type species Scoliodota theeli Heding, 1928.

Djakonov (in Djakonov, Baranova and Saveljeva, 1958) described Scoliodota lindbergi from the South Sakhalin and South Kuril Islands, with only scattered sigmoid hooks in the body wall. Evidently Djakonov was unaware of Clark’s 1946 monograph, and used Heding’s interpretation of Scoliodota.

Three years later Oguro (1961) described the new genus and species Scoliodotella uchidai from Hokkaido, with sigmoids hooks only in the body wall, scattered and not clustered. He also appeared to have been unaware of Clark’s 1946 monograph and did not refer to Scoliorhapis. He also was unaware of Djakonov’s paper published in Russian and did not compare his new species with Djakonov’s. Oguro (1961) differentiated his new genus Scoliodotella from Scoliodota (sensu Heding, 1928) in having scattered rather than clustered sigmoid hooks, although Heding did not mention the arrangement of hooks in diagnosis of Scoliodota.

Levin (1982) synonymized Scoliodotella uchidae with Scoliodota lindbergi. He followed Oguro’s opinion that the arrangement of sigmoid hooks in the body wall (scattered or clustered) is a character of the genus level, which distinguishes Scoliodotella and Scoliodota sensu Heding, 1928. Levin referred Scoliodota lindbergi to the Scoliodotella.

O’Loughlin & VandenSpiegel (2010) described two new species of Scoliorhapis from the Scotia Sea— S. biopearli and a 12-tentacled species S. massini. Unfortunately, poor preservation of specimens precluded detailed study of the internal anatomy and calcareous ring structure of these species. These authors considered that scattering or clustering of sigmoid hooks is not a genus level character and synonymized Scoliodotella with Scoliorhapis. They emended the diagnosis Scoliorhapis to include species with scattered as well as those with grouped sigmoid hooks, and with 10 and 12 tentacles.

Inoue & Kajihara (2012) re-described Scoliorhapis specimens from Akkeshi Bay, Hokkaido, Japan (the type locality of Scoliodotella uchidai) and confirmed Levin’s synonymization of this species with Scoliorhapis lindbergi.

Solis-Marin et al. (2014) described a new Scoliorhapis species, S. dianthus, from the side of Niigata, Honshu Is., Sea of Japan.

Together with Scoliorhapis stepanovi, n. sp. described below, Scoliorhapis now contains 6 valid species.

O’Loughlin & VandenSpiegel (2010: 76) emended the diagnosis of Scoliorhapis, to include species with 12 tentacles. However, the same authors, distinguished two genera of Taeniogyrinae, Taeniogyrus Semper, 1867 and Sigmodota Studer, 1876, based on tentacle number and correspondingly the structure of the calcareous ring: 10 in Taeniogyrus and 12 in Scoliodota. In our opinion, the number of tentacles in the Synaptida is a “good” character at the genus level, although reduction from 12 to 10 may have taken place independently in different clades (Smirnov, 2015). Thus we retain the 12-tentacled species Scoliorhapis massini to Scoliorhapis with reservation. Future study may show this species should be referred to a new genus or perhaps Sigmodota pending a latter revision.