Pleuroxus (Picripleuroxus) denticulatus Birge, 1879

Lee, Sue Yeon, Yoo, Jung Sun & Kim, Seung Tae, 2017, Recent progress in studies of the Cladocera (Crustacea: Branchiopoda) of South Korea with seven new records for the Korean Peninsula, Journal of Species Research 6, pp. 227-246 : 232

3. Pleuroxus (Picripleuroxus) denticulatus Birge, 1879

( Fig. 3)

Material deposited to NIBR. 5 parthenogenetic females from oxbow 1 of Isa River (N 34.9376°, E 127.455°) near Gyolyang Bridge , Jeollanam-do, coll. in 16 Jul 2017 by A.A. Kotov and K.S. Chae, NIBRIV0000812493 .

Parthenogenetic female. Body without very distinct sculpture, low in juveniles ( Fig. 3A, B) and higher in adults ( Fig. 3C), somewhat compressed laterally, posterior margin regularly curved from tip of rostrum to distinct postero-dorsal angle, posterior margin almost straight, ventral margin with exactly marginal setae of different length in different portions of it ( Fig. 3 D-G), postero-ventral angle with 1-2 thin and sparsely located denticles (distance between them is obviously larger than the denticle thickness at its base ( Fig. 3H, I). Head with a regularly curved, elongated rostrum, its tip sharp ( Fig. 3J, K) and projected exactly ventrally ( Fig. 3 A-C), ocellus somewhat smaller than compound eye. Head shield with two major head pores, postpore distance = about four interpore distance, two minute pores in midline, located somewhat closely to anterior major pore ( Fig. 3L, M). Labral keel large, with rounded apex ( Fig. 3N). Postabdomen long, in general slightly narrowing distally, ventral margin somewhat convex, preanal margin longer than anal one, almost straight; preanal angle well-expressed; anal margin concave; postanal angle expressed; postanal margin in general straight, but region of dorso-distal angle projected ( Fig. 3O). On distal portion, about 10 postanal teeth with size slightly increasing distally, each tooth accompanied of short series of additional small denticles, few (usually 3) distalmost teeth located on dorso-distal angle, very closely to each other. Postabdominal claw relatively thin, slightly curved, with two basal spines, length of the distal spine about 0.3 claw length, proximal spine two times shorter that distal one. Antenna I short, with antennular sensory seta located at 1/3 of appendage length from its distal end ( Fig. 3P), nine terminal aesthetascs of subequal size. Antenna II short, with two short sensory setae in coxal portion, basal segment with a minute spine distally ( Fig. 3Q). Antennal formula: setae 0-0-3/0-1-3, spines 1-0-1/0-0-1; a spine on proximal segment of exopod small; apical spines shorter than apical segments. Limb I with ODL supplied with a long seta and a small lateral seta; IDL with two large setae setulated distally ( Fig. 3R: 2 and 3) and a shorter naked seta (1). Size in our material 0.5-0.6 mm.

Notes. Note that P. denticulatus in Korea could be an anthropogenically introduced taxon. See further comments on P. quasidenticulatus .