Ilyocryptus cuneatus Štifter, 1988

Kotov, Alexey A., Jeong, Hyun Gi & Lee, Wonchoel, 2012, Cladocera (Crustacea: Branchiopoda) of the south-east of the Korean Peninsula, with twenty new records for Korea *, Zootaxa 3368, pp. 50-90 : 61-62

6. Ilyocryptus cuneatus Štifter, 1988

Figs 8–9

Synonymy. Ilyocryptus cuneatus Štifter, 1988 , p. 292–296, Figs 7–19; Tanaka 2001, p. 221, Fig. 3 A–E; Kotov & Štifter 2006, p. 76–81, Figs 2 G, 35–38; Kotov et al. 2011 a, p. 405.

Type locality. “West Bohemia, Březová reservoir on the river Teplá, 5 km south of Karlovy Vary” ( Štifter 1988), Czech Republic.

Localities in Korea. 6 a, 7 b, 8, 14 (see Fig. 1 and Table 1).

Parthenogenetic female. Body triangular-ovoid, postero-dorsal angle expressed ( Fig. 8 A). In anterior view, body thick, with thick and low dorsal keel, without lateral horns. Moulting incomplete. Ocellus small ( Fig. 8 B). Head shield with mandibular articulation as a small projection ( Fig. 8 C). Setae at ventral margin plumose ( Fig. 8 D). Each seta at posterior margin with a long, stout basal part, than with a series of 2–4 stout spine-like setules along one side in its basal portion, and with fine hairs in distal portion ( Fig. 8 E). Anus opens in the middle between base and distal extremity of postabdomen; preanal teeth 10–12, subequal in size, both doubled and single in the same specimen, few denticles on postabdomen base laterally ( Fig. 8 F). Paired spines shorter than large lateral setae. Postabdominal claw with a single denticle in distal part, no denticles in its middle part, distal and proximal spines on claw base subequal in size; setules situated on base of claw ventrally long ( Fig. 8 G). Antenna I relatively long, with transverse ridges ( Fig. 8 B). Proximal segment with a finger-like projection and few low hillocks ( Fig. 8 H). The longest aesthetasc about half the distal segment. Antenna II short, distal burrowing spine relatively short, with tip almost reaching or reaching distal border of basal segment ( Fig. 9 A). Both antennal branches short ( Fig. 9 B–C). Apical swimming setae relatively short, armed with short setules distally ( Fig. 9 D). Proximal lateral swimming seta shorter than distal one, both without hooks on tips and armed along one side with setules analogous to these of apical setae, and more stout and long setules along other side ( Fig. 9 E–F). Spine on second segment of exopod equal to or somewhat shorter than half of third segment ( Fig. 9 B–C). A large seta near ejector hooks of limb I. Gnathobase I as a setulated hillock. Limb VI with row of long setules along inner margin subdivided into six bundles by small incisions on the margin. Size in our material 0.61–0.83 mm.

Notes. The species is widely distributed in the Northern Palaearctic and Nearctic ( Kotov & Štifter 2006) and found close to Korea: Japan ( Tanaka 2001) and the Amur basin in Far East of Russia, where it is quite common ( Kotov et al. 2011 a). We found it also to be common in the Korean Peninsula, which could be the southernmost area of its distribution in Asia. Unfortunately, there is no information on its presence in China, and previous descriptions of ilyocryptids ( Chiang & Du 1979) are not detailed enough to separate sordidus -like species sensu Kotov & Elías-Gutiérrez (2009). Korean specimens are somewhat different from European ones in: (1) only few denticles on postabdomen base laterally; (2) ridges, although ill-expressed, on distal segment of antenna I. It is possible that populations from the Far East form a separate taxon, but this idea could be confirmed only in the course of a global revision of the cuneatus -like populations in the Palaearctic.