Camptocercus uncinatus Smirnov, 1971

Sinev, Artem Y., 2014, A comparative morphological analyses of four species of Camptocercus Baird, 1843 (Cladocera: Anomopoda: Chydoridae), Zootaxa 3895 (2), pp. 183-207 : 190-195

Camptocercus uncinatus Smirnov, 1971

( Figs. 5–8 )

Smirnov, 1971: 436–438, Fig. 128, 532; Dumont & Van De Velde, 1977: 87, fig. 6D, E; Dumont et al., 1979: 264, fig. 6; Negrea: 1982: 112–115, fig. 1; 1983: 309–312, fig. 126; Rane, 1985: 113–116, Fig. 1–8 ( latikae ); Margaritora, 1985: 289–290, fig, 114 ( australis ); Kim 1988, Fig. 58–59 (rectirostri s); Smirnov, 1998: 76–77, Fig. 51–57; Kotov, Jeong & Lee, 2012: 76–77, Fig. 21.

Material examined. Over 70 parthenogenetic and ephippial females, 3 males from Russia, Tyva Republic, Kyzyl city, flow-through ditch near the Tonmas-Sug River, 17.08.2010, coll. A.Y. Sinev.

Description. Parthenogenetic female. Body ( Fig. 5 A,C; 6A,B) with a well-expressed dorsal keel, moderately high, fusiform in lateral view (height/length ratio about 0.65 in adult), with maximum height in the second quarter of body; strongly compressed laterally. Dorsal margin highly arched, without depression between valves and head shield. Posterodorsal angle broadly rounded; posterior margin convex. Posteroventral angle broadly rounded. Ventral margin from almost straight to irregularly convex, with about 55–70 short ventral setae ( Fig. 5 D). Row of ventral setae ends at about 2/3 length of ventral margin, followed by numerous very short setules, subdivided into unclear groups. On posteroventral angle ( Fig. 5 E), groups of setules clearly defined; last setules in each group being largest, denticle-like. Anteroventral angle rounded. Valves with prominent diagonal lines, almost never anostomosing; in anteroventral portion of valves, curved upward. Keel oblique on both valves and shield.

Head ( Fig. 6 C, 7A) with sharp triangular rostrum, protruding downward. Head keel wide; distance from eye to the keel margin about 2.5–3 diameters of eye. Ocellus smaller than eye; distance from tip of rostrum to ocellus two times greater than distance between ocellus and eye. Three connected major head pores located at flattened portion of dorsal keel ( Fig. 6 D), PP about 1 IP. Lateral pores minute, located at little less than 1 IP distance from midline.

Labrum ( Fig. 7 C,D) of moderate size. Labral keel moderately wide (height about 1.5–2 widths), with moderately acute apex. Anterior margin of keel irregularly convex to straight; posterior margin almost straight, with 2–4 clusters of short setules, and small spinule in some specimens.

Thorax and abdomen ( Fig. 7 B) of similar length. Dorsal surface of middle abdominal segment saddle-shaped. Abdominal joint well-developed.

Postabdomen ( Fig. 5 F,G; 6E) very long and narrow, unevenly narrowing distally, without defined distal margin. Length about 6–6.5 heights. Ventral margin straight. Basis of claws elongated, bordered from dorsal margin by weak incision. Dorsal margin straight or weakly concave in postanal portion and weakly concave in anal one, with distal part about 4–4.5 times longer than preanal one; postanal portion 3.5 times longer than anal one. Preanal angle well expressed, prominent. Postanal angle weakly defined. Preanal margin convex. Postanal margin ( Fig. 5 H) with 11–13 single, triangular denticles, with serrated anterior margin distally, followed by 5–7 groups of smaller denticles-spinules in groups. Distalmost denticle large, with length exceeding the width of base of postabdominal claw, followed by denticles two times shorter. Postanal portion with 13–15 lateral fascicles of 6–8 thin setules; distalmost setula in each fascicle being longest. Postabdominal claw ( Fig. 5 I, 6J) straight, with curved distal portion; very long, about 1.5 lengths of preanal portion of postabdomen, with distinctive pecten of setules on dorsal margin. Several distal elements in basal pecten are spines, length of distalmost spine about width of the claw at the spot. Basal spine slender, about 1/6 length of the claw, with short spinules on dorsal margin.

Antennule ( Fig. 7 E) very long, curved at the base, length about 4.5 widths. Antennular seta short, about 1/4 length of antennule itself, arising at the middle of antennule. Nine terminal aesthetascs. Length of two longest aesthetascs about 1 and 0.9 length of antennule, respectively. All other much shorter and thinner, less than 1/2 length of antennule.

Antenna ( Fig. 7 F) with antennal formula: setae 0-0-3/0-1-3; spines 1-0-1/0-0-1. Basal segment robust, with very short seta between branches. Branches long and slender; in both branches basal segment 1.5 times longer than apical segment, middle segment being shortest, 2 times shorter than basal segment. Seta arising from middle segment of endopodite of same length as endopodite. All apical setae of similar thickness. All spines very short.

Limb I large and massive ( Fig. 8 A,B). Epipodite oval, with projection three times longer than epipodite body.

Accessory seta long, about 2/3 length of ODL seta. ODL seta thick, with short setules in distal portion. IDL with three setae and two clusters of very short setules. IDL seta 1 of moderate size, about 1/3 length of ODL seta. Setae 2 and 3 thick, curved, hook-like with thin, setulated distal portion; seta 3 slightly shorter than ODL seta; seta 2 about 2/3 length of seta 3. Endite 3 as in the previous species. Endite 2 similar to the previous species but seta e of moderate length, almost two times shorter than limb itself; seta f slightly shorter. Endite 1 as in the previous species Ventral face of limb with clusters of short setules. Ejector hook, and maxillar process elongated, thick, with short setulated seta in distal part.

Limb II ( Fig. 8 C,D) as in the previous species, but exopodite with curved backward seta.

Limb III ( Fig. 8 E,G). Epipodite oval, with finger-like projection as long as epipodite itself. Exopodite ( Fig. 8 E) of irregular shape, with seven setae; seta 3 being longest, seta 6 and 7 about 2/3 and 1/2 length of seta 3 respectively, setae 1 and 4 less than 1/3 length of seta 3, setae 2 and 5 short. Seta 3 unilaterally armed with long thin setules in distal half; seta 4 armed with long thick setules; setae 6–7 naked; other setae armed with short setules. Inner portion of limb as in the previous species, but basal endite with 4 stiff setae (a–d) of unusual for Aloninae morphology, with especially wide bases and wide distal part, strongly increasing in length basally; seta a four times shorter than seta d.

Limb IV ( Fig. 8 H,J) as in the previous species, but inner portion with three very small inner setae (a–c).

Limb V ( Fig. 8 K) much smaller in size than in previous species. Exopodite with seta 2 being longest. Setae 1–2 of similar length; seta 3 and 4 about 2/3 and 1/3 length of seta 2 respectively; setae 1–3 of exopodite of same length; seta 4 four times shorter. Filter plate with single short seta.

Ephippial female ( Fig. 5 J) with body slightly higher than in parthenogenetic female. Ephippium yellowbrown, with sculpture in shape of longitudinal lines thicker than on the rest of valve.

Male. Body lower than in female, fusiform ( Fig. 5 K, 6G), with well developed dorsal keel on head and valves; height/length ratio about 0.6; maximum height before the midline. Body strongly compressed laterally. Head ( Fig. 7 G) with truncated rostrum. Ocellus and eye slightly larger than in female.

Postabdomen ( Fig. 5 L, 6I) moderately long and narrow, unevenly curved and narrowing distally in postanal portion, without defined distal margin. Length about 5 heights. Sperm ducts opening located at the end of postabdomen at some distance from the basis of claws. Weak incursion between basis of claws and dorsal margin.

Dorsal margin concave in postanal portion and convex in anal one, with postanal portion 1.8–2 times longer than anal one. Preanal and postanal angles not defined. Preanal margin convex. Marginal denticles replaced with clusters of setules, 3–4 setules in each ( Fig. 5 M). Lateral fascicles of setules as in female. Postabdominal claw ( Fig. 5 L, 6J) unevenly curved at the middle, shorter than in female, with basal pecten consisting of about 20 setules; length of distalmost spines less than width of the claw at the spot. Basal spine very short, addressed to the claw, with 7–8 very long setules.

Antennule ( Fig. 7 H) shorter than in female, curved in basal portion, reaching before the end of rostrum; length about 5 widths. Male seta long, arising at 4/5 distance from the base, about 2/5 length of antennule. Ten terminal aesthetascs of about 1/3 – 2/3 length of antennule.

Limb I ( Fig. 8 L–M) with U-shaped copulatory hook, 2 times shorter than limb itself. IDL setae 1–3 strongly reduced in size in comparison with those of female; setae 2 and 3 not hook-like, with long distal portion, armed with thin setules; male seta straight, of moderate thickness, as long as IDL seta 2. Ventral face of limb below copulatory hook with a row of 30–35 short setules. Endite 3 with inner seta longer and thinner than in female.

Size. In instar I juvenile female, length 0.46–0.53 mm, height 0.3–0.34 mm. In instar II juvenile female, length 0.59–0.62 mm, height 0.37–0.41 mm. In adult females, length 0.73–0.85 mm, height 0.50–0.54 mm. In adult males, length 0.55–0.59 mm, height 0.36–0.38 mm.

Notes. Morphology of females from studied populations corresponds well to the previous description of the species ( Smirnov 1971, 1998; Kotov et al. 2012). Morphology of specimens from Romania and Italy ( Negrea 1983; Margaritora 1985; Margaritora & Vagaggini 2002) did not differ from that of Asian populations. But C. uncinatus , not recorded from Spain, Germany, Norway and European Russia, seems to be confined to South Europe. Records from Turkey ( Yalim 2001), Iran, Ethiopia, Egypt and Lake Victoria ( Smirnov 1998) suggest that the species should be also present in South-West Asia and North-East Africa. Records from Guatemala ( Smirnov 1998) should be re-checked, presence of C. uncinatus s. str. in East Hemisphere contradicts Frey's (1982) noncosmopolitanism paradigm.

Figures

FIGURE 1. Camptocercus oklahomensis from USA, Louisiana, Pointe Coupe Parish, roadside ditch about 2 miles north from Highway 190 on Highway 1. A, outline of juvenile female of instar II. B – K, parthenogenetic female. B – C, lateral view. D, head shield. E – F, ventral margin of valve. G, posteroventral angle of valve. H – I, postabdomen. J, distal portion of postabdomen. K, postabdominal claw. L, ephippial female. M – N, juvenile male of instar II. M, outline. N, postabdomen. O – P, adult male. O, lateral view. P, postabdomen.

FIGURE 2. Camptocercus oklahomensis from USA, Louisiana, Pointe Coupe Parish, roadside ditch about 2 miles north from Highway 190 on Highway 1. A – F, parthenogenetic female. A – B, lateral view. C, dorsolateral view. D, posterior part of ventral margin of valves. E, postabdomen. F, antenna. G – I, ephippial female. G, lateral view. H, dorsal view. I, sculpture of ephippium. J – K, male. J, lateral view. K, postabdomen. Scale bars denote 0.1 mm for A – C, G – H, J, 0.05 mm for D – E, I, K, 0.01 mm for I.

FIGURE 3. Camptocercus oklahomensis from USA, Louisiana, Pointe Coupe Parish, roadside ditch about 2 miles north from Highway 190 on Highway 1. A – G, parthenogenetic female. A, head. B, head pores. C – D, labrum. E, antennule. F, antenna. G, antennule of instar II juvenile male. H – I, adult male. H, head. I, antennule and outline of rostrum.

FIGURE 4. Camptocercus oklahomensis from USA, Louisiana, Pointe Coupe Parish, roadside ditch about 2 miles north from Highway 190 on Highway 1. A – J, thoracic limbs of parthenogenetic female. A, limb I. B, IDL of limb I. C, limb II. D, exopodite of limb II. E, exopodite of limb III. F, inner portion of limb III. G, exopodite of limb IV. H – I, inner portion of limb IV. J, limb V. K – L, thoracic limb I of instar II juvenile male. M – N, thoracic limb I of adult male.

FIGURE 5. Camptocercus uncinatus from Russia, Tyva Republic, Kyzyl city, flow-through ditch near the Tonmas-Sug river. A – B, outlines of juvenile female of instar I and II. C – I, parthenogenetic female. C, lateral view. D, ventral margin of valve. E, posteroventral angle of valve. F – G, postabdomen. H, distal portion of postabdomen. I, postabdominal claw. J, ephippial female. K – N, adult male. K, lateral view. L, postabdomen, M, distal portion of postabdomen. N, postabdominal claw.

FIGURE 6. Camptocercus uncinatus from Russia, Tyva Republic, Kyzyl city, flow-through ditch near the Tonmas-Sug river. A – F, parthenogenetic female. A – B, lateral view; C, head. D, head pores. E, postabdomen. F, postabdominal claw. G – J, adult male. G, lateral view. H, head. I, postabdomen. J, postabdominal claw. Scale bars: 0.1 mm for A – B, G, 0.05 mm for C, E, H – I, 0.01 mm for D, F, J.

FIGURE 7. Camptocercus uncinatus from Russia, Tyva Republic, Kyzyl city, flow-through ditch near the Tonmas-Sug river. A – F, parthenogenetic female. A, head. B, abdomen. C – D, labrum. E, antennule. F, antenna. G – H, adult male. G, head. H, antennule.

FIGURE 8. Camptocercus uncinatus from Russia, Tyva Republic, Kyzyl city, flow-through ditch near the Tonmas-Sug river. A – G, thoracic limbs of parthenogenetic female. A, limb I. B, IDL of limb I. C, limb II. D, exopodite of limb II. E, exopodite of limb III. F – G, inner portion of limb III. H, exopodite of limb IV. I – J, inner portion of limb IV. K, limb V. L – M, thoracic limb I of adult male and its IDL.