Stolus parafusus ( Deichmann, 1941 ) Thandar, 2021

Thandar, Ahmed S., 2021, Nomenclatural changes in some sea cucumbers with the erection of a new genus and description of a Thyone? juvenile (? n. sp.) from the Gulf of California (Echinodermata: Holothuroidea: Dendrochirotida), Zootaxa 5026 (4), pp. 507-526 : 516-517

Stolus parafusus ( Deichmann, 1941) n. comb.

Figure 6

Thyone parafusus Deichmann, 1941: 106–107 , pl. 18, figs. 7–12; Solis-Marin et al. 2009: 80–81, pl. 15; Jacobson, et al 2015:84.

Diagnosis (see Deichmann, 1941).

Material examined. USNM E2221 , North Pacific Ocean , Mexico, Baja, California, det. M. Wright, 1977, 1 spec.

Remarks. This species was established on the basis of two specimens a few cm long, collected from Tenacatita Bay, Mexico, at about 45 m. The current specimen is elongated, about 155 mm long, with a bloated middle but attenuated ends. The tentacles are well branched and the calcareous ring incised, with deeply cleft radials. The body wall ossicles ( Figure 6A ), as described by Deichmann (1941) and Jacobson et al. (2015), comprise tables with a four- holed disc with often a short handle on one side and a spire of moderate height, terminating in a few teeth. Deichmann described the tube feet tables in the type as possessing a three-pillared spire, but in the current specimen this is not clearly evident. The introvert possesses numerous tables with a multilocular disc with the spire welldeveloped or reduced. The tentacle deposits comprise numerous rosettes but at the bases adjoining the introvert, there are numerous tables with a reduced disc. Deichmann (1941), however, described the tentacles as being packed with perforated, multilocular plates of different sizes – perhaps referring to the reduced table discs. The delicate rods described by Deichmann to be present in the terminal branches were not detected in the specimen at hand nor by Jacobson et al. (2015).

This species comes very close to Deichmann’s (1930) T. pseudofusus originally described from Yucatan, as a tapering form with mouth and anus directed upwards. This is the shape of the current specimen. According to Deichmann (1930), T. pseudofusus has tables with a short robust spire with numerous teeth and the tentacles lack the perforated plates present in the tentacles of T. parafusus . This is well illustrated by Jacobson et al. (2015). The placement of both these species in the genus Thyone is doubtful. Hence, due to the often presence of heavily knobbed table discs and handles or half-rings to most of the body wall tables ( Figure 6A ), both these species are here transferred to Stolus . S. parafusus n. comb. strongly resembles S. crassus Liao & Pawson, 2001 , from China, not only in body wall ossicles but also in the presence of tables in the introvert and rosettes in the tentacles. Hence, there is little justification in retaining these species in Thyone as none corresponds with the characters of the type species ( T. fusus ) of this genus.

Figures

FIGURE 6. Stolus parafusus (Deichmann, 1941) n. comb. USNM E2221. Knobbed tables/buttons from body wall; B. Table from tube foot. (All to same scale).