Cliona argus var. laevicollis Thiele, 1898

(Fig. 8A)

Cliona argus var. laevicollis Thiele, 1898: 41, pl. VIII fig. 15; Hoshino 1987: 14 (listed only); Ise 2017: 373 (listed only).

The variety was described by Thiele from S of Enoshima, Japan, (Doderlein’s map nr. 17) approximate coordinates 35.2667°N 139.6667°E, depth 140 m (type material not identified, not in online type catalogues of ZMB and MZS, possibly in ZMB labeled only as Cliona argus). The variety was judged to be different from the typical variety also described by Thiele (1898: 41, pl. VIII fig. 14, from Hakodate, Hokkaido, Japan, approximate coordinates 41.72°N 140.7°E, ‘holotype’ two specimens ZMB 2200 and 2745) in the size of the papillae, and differences in the size of the smaller tylostyle category (240 µm in the var. laevicollis and 120–140 µm in the typical variety). A further difference mentioned by Thiele is the depth of occurrence of the variety laevicollis (140 m), although no depth was mentioned for the typical variety, presumably because it was from shallow water. Thiele also made remarks on the variability of the tylostyle heads in the typical variety and reduced blunt shapes in some tylostyles of the var. laevicollis, but such variability is common in many Cliona species. The short spirasters with knobby conical rays of both varieties (resembling those described for e.g. Cliona caledoniae Van Soest & Beglinger, 2009: 330) were similar in shape and size. In view of the latter and the likely variability of tylostyles in Cliona s.l. I deem it unlikely that two Cliona species with such characteristic microscleres occur almost sympatrically. Accordingly, I propose to merge the two varieties into a single species Cliona argus Thiele, 1898 .