Camptocercus streletskayae Smirnov 1998

Camptocercus streletskayae Smirnov, 1998

(fig. 6)

Smirnov 1998: 70–71, fig. 28–44, Pl. 2; Sinev 2015a: 170–174, fig. 1–2. Material examined. Over 150 parthenogenetic females and over 10 males from water body near Jaap pond, Barrow, Alaska, USA, 31.08.1975, coll. J. Honey, DGF 6327.

Description. Parthenogenetic female (Fig 6A–J). From studied populations fully agree with the earlier descriptions (see Sinev 2015a); diagnostic features of the species include peculiar morphology of marginal denticles of postabdomen (Fig 6F–G) and postabdominal claw (Fig 6H–J), and IDL with hook-like, thick seta 1 (Fig 6J). The only difference between Asian and American populations is the absence of denticles on posteroventral angle of valves in the latter ones (Fig 6B).

Male. General. Body lower than in female, low oval (Fig. 6K), with well developed dorsal keel on head and valves; height/length ratio about 0.57; maximum height before the midline. Body strongly compressed laterally.

Head (Fig. 6L) with truncated rostrum. Ocellus and eye of same proportion as in female.

Postabdomen (Fig. 6M) long and narrow, evenly narrowing distally in postanal portion, without defined distal margin. Рostabdomen height at postanal angle 3 times greater than at the distalmost group of marginal setulae. Length about 5.5 height. Sperm ducts opening located laterally at the end of postabdomen at some distance from the basis of claws. Weak incursion between basis of claws and dorsal margin. Dorsal margin weakly concave straight in postanal portion and straight in anal one, with postanal portion four times longer than anal one. Рreanal and postanal angles weakly defined. Рreanal margin convex. Marginal denticles replaced with clusters of 4–9 setulae, in distalmost groups setulae rather thick. Lateral fascicles of setulae as in female. Рostabdominal claw strongly bent at the 1/3 length from the base, shorter than in female, with basal pecten consisting of about 10 setulae; length of distalmost spines less than width of the claw at the spot. Basal spine short, curved, adpressed to the claw, with about 10 very short setulae.

Antennule (Fig. 6N) shorter than in female, weakly curved, reaching before the end of rostrum. Length about 4 widths. Male seta long, about 1/3 length of antennule, arising at 1/3 distance from the base. Ten terminal aesthetascs of about 1/3 – 2/3 length of antennule.

Limb I (Fig. 6O –Р) with U-shaped copulatory hook, 1.5 times shorter than limb itself. IDL seta 1 strongly reduced in size in comparison with that of female, thin, and about 1/3 length of seta 3; setae 2 and 3 shorter and thinner than in female; male seta almost straight, of moderate thickness, about 2/3 length long of IDL seta 3. Ventral face of limb below copulatory hook with several rows of short thick setulae (over 60 in total) and row of about 8 shorter setulae at endite 3 base.

Size. Length of males in studied material was 0.66–0.69 mm, height 0.38–0.4 mm.

Distribution. North of the Eastern Siberia, Chukotka, Alaska. This is the first record of C. streletskaye in North America.