Sthenocephalus indicus Koehler, 1898

Baker, Alan N., Okanishi, Masanori & Pawson, David L., 2018, Euryalid brittle stars from the International Indian Ocean Expedition 1963 - 64 (Echinodermata: Ophiuroidea: Euryalida), Zootaxa 4392 (1), pp. 1-27 : 5-6

Sthenocephalus indicus Koehler, 1898

( Figs. 2E–F , 3 )

Sthenocephalus indicus Koehler, 1898: 112 , pl. 5 figs. 48,49; Döderlein, 1927: 82, pl. 8 figs. 3-6.

Material Examined. USNM 1072462 , Anton Bruun Cruise 1 Station 17, southern Andaman Sea, 7° 38’N 97° 09’E, 275–280m, 21 March 1963, 1 specimen ( Fig. 2E–F ).

Remarks. This specimen (18.5 mm disc diameter and 100 mm arm length) has 22 arm segments before the first arm branch ( Fig. 2E–F ), thus identifying it as S. indicus rather than the closely related S. anopla ( H. L. Clark 1911) , from the East China Sea, which has 12–17 pre-branch segments ( Irimura & Kubodera 1998). There are at least 6 arm bifurcations in total. The distal ends of the radial shields carry granules and fine tubercles ( Fig. 2E ), and the arms have a double median row of small round tubercles up to the first branch ( Fig. 3A ), and small grains thereafter over the rest of the arm ( Fig. 3B ). There are hook-shaped arm spines distally ( Fig. 3C ), and two clubshaped arm spines proximally ( Fig. 3D ). The lateral arm plates meet on the oral midline ( Fig. 3D ); this is a feature of this genus.

The type specimen of S. indicus was collected at Gaspar Strait in Indonesia by the survey vessel Investigator ( Koehler 1898) , and further material has since been recorded from the Indian Ocean in 36–467 meters. The present specimen was taken from the outer shelf in the southern Andaman Sea between Phuket and the Nicobar Islands. The material described by Liao & A. M. Clark (1995) as Sthenocephalus indicus may yet prove to be Sthenocephalus anopla ( Liao & A. M. Clark 1995) . Euryale anopla H. L. Clark, 1911 , from southern Japan, was redescribed by Mortensen (1933a) as Stenocephalus (sic) indicus var. anopla . Irimura & Kubodera (1998) restored anopla as a distinct species in their new combination Sthenocephalus anopla ( H. L. Clark, 1911) , a step that was followed by Fujita & Irimura (2005).

Figures

FIGURE 2. Asteromorpha capensis (USNM 1072577) (A–D) and Sthenocephalus indicus (USNM 1072462) (E–F). A, aboral view; B, oral view; C, aboral disc; D, oral disc; E, aboral view; F, oral view.

FIGURE 3. Sthenocephalus indicus (USNM 1072462) (A–D). A, aboral basal portion of the arm; B, aboral distal portion of the arm; C, oral distal portion of the arm; D, oral basal portion of the arm. Abbreviations. AS, arm spine; LAP, lateral arm plate.