Baicalocandona Mazepova, 1976

Karanovic, Ivana & Sitnikova, Tatiana Ya., 2017, Morphological and molecular diversity of Lake Baikal candonid ostracods, with description of a new genus, ZooKeys 684, pp. 19-56 : 30

Genus Baicalocandona Mazepova, 1976

Type species.

Baicalocandona bivia Mazepova, 1976

Amended diagnosis.

Shell shape (always) trapezoidal, surface ornamented in most species, at least in some parts. A1 7, 6 or 5-segmented. Male A2 with t-setae transformed into sensory setae, z-setae transformed into claws. Female A2 with G2-claw as long as G1 or G3. Exopod of A2 consisting of small plate and three setae of which one long. Male prehensile palps asymmetrical and both with hook-like fingers, but right palp with shorter, stockier and considerably less hook-like finger. L6 with basal seta and with one seta on each endopodal segment, except last, which carries two setae and one claw. L7 with only d1- and dp-seta on basal segment, e- and f-setae missing, g-seta long; terminal segment with short h1-seta and h2- and h3-setae equally long; penultimate segment fused without any notable subdivision. UR with both claws and setae present. Zenker organ with 4+2 whorls of spines. The anterior part (cap) more hemispherical and margin not sclerotized, lattice-like structure not well-developed; cap also with long radiating spine-like projections. Hemipenis with relatively large a-lobe not projecting laterally. M-peace terminally foot-like; ejaculatory process (bursa copulatrix) not terminally pointed, and with broad, rounded, finger-like extension; this process also with lateral thorn-like ornamented part.

Remarks.

Baicalocandona at the moment includes 11 species and 11 subspecies. According to the diagnosis ( Mazepova 1976, 1990), all species have a trapezoidal valve shape, males have sexual bristles on the second antenna, and the Zenker organ bears six whorls of spines. One species we redescribe below falls within this diagnosis, although it was originally described in Candona . We also noted some other morphological characters that improve the genus diagnosis, such as a very short finger on the right prehensile palp, a short basal seta (d1) on the walking leg, undivided penultimate segment of the cleaning leg, a foot-like shape of the M-peace of hemipenis, and ejaculatory process finger like and pronounced. Females also seem to have a long G2-claw on the second antenna, and Zenker organ has long spine-like projections on anterior end. Based on the redescription of two Pseudocandona species, P. ceratina and P. gajewskaye , only the absence of the male sexual bristles on the second antenna separates this genus from Baicalocandona . The number of A1 segments, as well as the number of setae on the second segment of the Md-palp seems to be variable. Baicalocandona is very similar to the European subterranean genus, Schellencandona , both in the shell shape and morphology of the hemipenis.