Cobanocythere sp.

Smith, Robin James & Chang, Cheon Young, 2022, Two new species of non-marine Ostracoda (Crustacea) of the genera Vestalenula Rossetti & Martens, 1998 (Darwinuloidea) and Microloxoconcha Hartmann, 1954 (Cytheroidea) from Tsushima, Japan, and a summary of the non-marine ostracod fauna of the island, Zootaxa 5150 (4), pp. 529-555 : 541

Cobanocythere sp.

( Fig. 6A–D )

JAPAN — Nagasaki Prefecture, Tsushima • 2 ♀♀, one with soft parts dissected in glycerine and sealed in a glass slide, valves stored dry in a micropalaeontological slide, one stored whole and dry in a micropalaeontological slide; Kamitsushima-machi Kawachi ; 34.67306º N, 129.42726º E; alt. 1 m; 30 Aug. 2019; Robin J. Smith, Cheon Y. Chang, Jimin Lee leg.; small tidal river with concrete banks, substrate flattened pebbles of sedimentary rock, low tide, salinity 0.3%; sample 190830-03A .

Brief description. Carapace length 386–398 µm (n=2), height 146 µm (n=1), width 231 µm (n=1). Lateral view very elongate with maximum height anterior of mid-length ( Fig. 6A & B ). Dorsal margin strongly curved, ventral margin flattened to slightly convex anteriorly. Anterior margin tightly rounded with apex below mid-length, posterior margin sharply angled. Dorsal view tear-drop shaped, with pointed anterior end and rounded posterior end ( Fig. 6D ). Ventral view with five to six (sub) parallel ridges running lengthwise on ventral surface of each valve ( Fig. 6C ).

Remarks. This is probably an undescribed species, but considering the paucity of specimens and lack of males, it is not described herein. This species can be distinguished from most others of the genus by its dorsal view, which is much wider and tear-drop shaped. Two species that come close are Cobanocythere ? japonica Schornikov, 1975 from Japan, and Cobanocythere guttaeformis Gottwald, 1983 from the Galapagos Islands. Compared with C.? japonica the posterior margin is significantly more strongly angled in Cobanocythere sp. Additionally, Cobanocythere sp. has five to six (sub) parallel ridges running lengthwise on the ventral surface of each valve, which have not been reported for C.? japonica . Cobanocythere guttaeformis has a lower height in lateral view compared with Cobanocythere sp. , and also appears to be missing the ridges on the ventral surface of the valves.

Distribution and ecology. This species was found once, in the same sample as Microloxoconcha semicircularis sp. nov. (see below).

Figures

FIGURE 6. A–D, Cobanocythere sp. A, LV, ext. B, RV, int. C, Cp, vent., anterior to right. D, Cp, dor., anterior to left. E–J, Microloxoconcha semicircularis sp. nov. (female, LBM 1430009564). E, LV, ext. F, RV, ext. G, LV, ext., detail of postero-ventral margin. H, RV, ext., detail of postero-ventral margin. I, LV, int. J, RV, int. Scale bar = 100 µm for A, B, E, F, 126 µm for G–J, and 23 µm for C & D. White triangles indicate the two semicircular depressions on the valves.