Simocephalus congener ( Koch, 1841 )

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 : 58-60

4. Simocephalus congener ( Koch, 1841)

Fig. 6

Synonymy. Daphnia congener Koch, 1841 , p. 35.13 (no figures); Orlova-Bienkowskaja 1998, p. 25–26, Fig. 34; Orlova- Bienkowskaja 2001, p. 78–80, Figs 51–57, 114–115, Pl. 6: fig. 30; Kotov et al. 2011a, p. 405.

Type locality. Not indicated in the original description. Probably in Germany ( Orlova-Bienkowskaja 1998). Locality in Korea. 6a (see Fig. 1 and Table 1 ).

Parthenogenetic female. Body subovoid, dorsal margin with a shallow cervical incision, postero-dorsal angle broadly rounded, without any projection and prominence anterior to it, posterior margin almost straight, fluently turned to ventral margin without any angle, ventral margin convex ( Fig. 6 A). Head with a small rostrum; large compound eye occupies antero-ventral portion of head; ocellus small, of irregular shape ( Fig. 6 B). Labrum fleshy, with a large, setulated distal labral plate. Valve with a row of numerous setae submarginally near ventral margin; in its posterior portion it turns to a row of grouped setules, with size increasing dorsally in each series ( Fig. 6 C). Postabdomen with an undulated preanal margin, strongly prominent preanal angle, convex anal margin, undistinguishable postanal angle and a very small postanal margin ( Fig. 6 D). Few strong, single postanal teeth, bearing minute setules ( Fig. 6 E). Postabdominal claw long, slightly curved, with about 15 small, thin teeth in first (proximal) pecten, more than 20 relatively thin teeth in second pecten, and numerous fine setules in third pecten ( Fig. 6 E). Antenna I short, with a strong antennular sensory seta on a special projection and nine terminal aesthetascs ( Fig. 6 B, F). Antenna II long, antennal formula: setae 0-0-1-3/1-1-3, a small spine on proximal segment of exopod ( Fig. 6 G). Limb I as illustrated in Fig. 6 H. Other limbs described by Orlova-Bienkowskaja (1998). Size in our material 1.5–1.9 mm.

Notes. Orlova-Bienkowskaja (2001) stated that "This species was previously confused with S. exspinosus , so its range needs to be redefined. It occurs with certainty in Central and Eastern Europe and Siberia". Recently this taxon was also found in the Far East of Russia ( Kotov et al. 2011b). Most probably, S. exspinosus ( Koch, 1841) illustrated by Kim & Yoon (1987) and Yoon (2010) could also be S. congener , but the distal portion of the postabdominal claw was illustrated inadequately. At this moment, this taxon could be regarded as Palaearctic, penetrating to the South.

Figures

FIGURE 6. Simocephalus congener (Koch, 1841), parthenogenetic female from Bak Sil Ji 1, locality 6 a: A, lateral view; B, head; C, postero-ventral portion of valve, inner view; D, postabdomen; E, its distal portion; F, antenna I; G, antenna II; H, limb I. Scale bars: 0.1 mm.