Camptocercus dadayi Stingelin 1913

Sinev, Artem Y., 2015, Morphology and phylogenetic position of three species of genus Camptocercus Baird, 1843 (Cladocera: Anomopoda: Chydoridae), Zootaxa 4040 (2), pp. 169-186 : 179-183

Camptocercus dadayi Stingelin 1913

( Figs. 6–8 )

Daday 1902: 266 –269, Tab. X, fig. 2–5 ( australis ); Daday 1905: 189 ; Tab. 12, fig. 4 ( australis ); Stingelin 1913: 620 –621, fig. 21–22 (australi s var. dadayi ); Smirnov 1971, p. 438, fig. 539 ( lilljeborgi var. dadayi ); Rey & Vasquez 1986: 177 –180, fig. 1–13; Frenzel 1987: 498 –501, Abb. 4A–H ( australis var. dadayi ); Ciros-Pérez & Elías-Gutiérrez 1996: 298, fig. 3; Elías- Gutiérrez et al. 1997: 69–70, fig. 14–18.

Type locality. " 2528 m ü.M., 1/2 Tagesreise von Bogota, auf einem Hochplateau über dem Magdalenenstromtale", Colombia.

Lectotype. Parthenogenetic female at Naturmuseum Olten ( Switzerland), T. Stingelin collection, slide II/44, established by Frenzel (1987).

Studied material. Over 40 parthenogenetic females from Mexico, a channel at El Guao lagoon, 18.28964º N, 92.32584º W, 13.01.1998, coll. M. Elías-Gutiérrez & I. Castellanos-Osorio, AAK 2002-071.

Description. Parthenogenetic female. General. Body ( Fig. 6 A–C, 7A–C) with a well-expressed dorsal keel, moderately high, slightly fusiform in lateral view (height/length ratio about 0.65 in adult), with maximum height before at 1/3 of the body, strongly compressed laterally. Dorsal margin highly arched, without a 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 55–65 short ventral setae ( Fig. 6 D, 7D). Row of ventral setae ends at the middle of ventral margin, followed by numerous very short setulae, subdivided into unclear groups. Posteroventral angle without denticles ( Fig. 6 E). Valves with prominent diagonal lines, rarely anastomosing, no striae on valves and head shield.

Head ( Fig. 6 F) with moderately wide rostrum truncated at the end, protruding downward. Head keel moderately wide; distance from compound eye to the keel margin about 2 diameters of eye. Ocellus much smaller than eye; distance from tip of rostrum to ocellus 1.5 times greater than distance between ocellus and eye. Three major head pores with narrow connection between them located at the flattened portion of dorsal keel ( Fig. 7 E), PP less than 1 IP. Lateral pores minute, located at about 1.5 IP distance from midline.

Labrum ( Fig. 8 A, B) rather large. Labral keel moderately wide (height of about 1.2–1.3 widths), with a rounded apex. Anterior margin of keel convex, posterior margin weakly convex, with two clusters of short setules.

Thorax and abdomen ( Fig. 7 F) of similar length. Dorsal surface of middle abdominal segment saddle-shaped. Abdominal joint ( Fig. 6 G) well-developed.

Postabdomen ( Fig. 6 H, I, 7F) very long and narrow, narrowing distally in basal part, with almost parallel margins in distal half of postanal part, without defined distal margin. Length about 5 heights. Ventral margin straight. Basis of claws elongated, bordered from dorsal margin by unclear incision. Dorsal margin weakly concave in postanal portion and weakly concave in anal one, with distal part about 5.5 times longer than preanal one; postanal portion 3 times longer than anal one. Preanal angle well expressed. Postanal angle weakly defined. Preanal margin weakly convex. Postanal margin ( Fig. 6 J, 7G) with 10–14 composite denticles with serrated margin, followed by 4–7 groups of elementary denticles. Distalmost 1–3 denticles long, with length slightly less than width of postabdominal claw base, following denticles much shorter. Postanal portion with 13–15 lateral fascicles of about 5–10 setules; number of setulae by fascicle decreased distally. Distalmost setula in each fascicle being longest and much thicker than others. Postabdominal claw ( Fig. 6 K, 7H) weakly curved, long, about 2 lengths of preanal portion of postabdomen, with distinctive pecten of setulae on dorsal margin. Several distal elements in basal pecten are massive spines; length of distalmost spine about 1.5 width of the claw at the spot. Basal spine of usual shape, about 0.15 length of the claw, with short spinules on dorsal margin.

Antennule ( Fig. 6 L) long, slightly curved, length about 4–4.5 widths. Anterior face of antennule with 3 clusters of short setulae. Antennular seta short, about 1/4 length of antennule itself, arising at 2/3 distance from the base of antennule from well-defined tubercle. Nine terminal aesthetascs, two longest of about 4/5 length of antennule, other of 1/2–2/3 length of antennule.

Antenna ( Fig. 6 M) similar to that of the previous species.

Limb I large and massive ( Fig. 8 C,D). Epipodite oval, with a projection two times longer than epipodite itself. Accessory seta long, about 1/3 length of ODL seta. ODL seta thick, with thin setulae, longer than in two previous species, in distal portion. IDL with three setae and two clusters of very short setulae. IDL seta 1 thin, with narrow base, with length about 1/3 length of ODL seta. Setae 2 and 3 massive, curved, 1.5 times thicker than ODL seta, with distal portion armed by strong spines, length of basalmost spines equal or exceeding width of seta base; seta 3 about 2/3 length of ODL seta, seta 2 only slightly shorter than seta 3. Endite 3 with setae of similar length, seta 1 much longer than in the previous species. Endites 1 and 2 of similar morphology than two previous species. Ventral face of limb with clusters of short setulae. Two ejector hooks, one 1.5 times longer and slightly thicker than other.

Limb II ( Fig. 8 E) similar to that of the previous species, but exopodite oval, with longer seta.

Limb III ( Fig. 8 F,G). Epipodite oval, with finger-like projection as long as the epipodite itself. Exopodite of irregular shape, much larger than in the previous species, with seven setae: seta 3 being longest; seta 6 and 7 of similar length, about 1/2 length of seta 3; setae 1 and 4 of similar length, about 1/3 length of seta 3; seta 2 short, seta 5 very short. Seta 3 unilaterally armed with long setules along all its length; setae 6–7 armed with very short setulae; seta 5 naked, seta 4 with long thick setulae in distal part, setae 1–2 plumose. Inner portion similar to that of C. streletskaye .

Limb IV ( Fig. 8 H–J). Preepipodite setulated; epipodite with finger-like projection 1.5 times longer than epipodite itself. Exopodite of irregular shape, with six setae, seta 3 being longest. Setae 5 and 6 of about 1/2 and 1/ 3 length of seta 3, respectively; other setae very short. Setae 1–2 and 5–6 naked; seta 3 and 4 plumose. Inner portion similar to that of C. streletskaye .

Limb V ( Fig. 8 K–L). Preepipodite setulated; epipodite oval, with thick finger-like projection 1.5 times longer than epipodite itself. Exopodite moderately large, not separated into two lobes, with four plumose setae evenly decreasing in length basally; seta 4 three times shorter than seta 1. Inner lobe long and narrow, with densely setulated end. At inner face, two setae densely setulated in distal part, distal seta almost 2 times longer than basal one. Filter plate not found.

Ephippial female. According to Elías-Gutiérrez et al. (1997), ephippium with parallel longitudinal grooves, deeper on the dorsal region.

Male. According to Elías-Gutiérrez et al. (1997), body lower than in female, height/length ratio 0.6; maximum height at 1/3 of the length. Body strongly compressed laterally. Head with a strongly truncated rostrum. Ocellus larger than in female, eye of same size as in female. Postabdomen long and narrow, evenly narrowing distally in postanal portion, without defined distal margin. Length about 5.5 heights. Sperm duct openings located at the end of postabdomen above the elongated base of claws. Incursion between basis of claws and dorsal margin weakly defined. Dorsal margin almost straight in both anal and postanal portions, with postanal portion 2 times longer than anal one. Preanal angle well-defined, postanal angle not defined. Preanal margin convex. Marginal denticles replaced with clusters of short setulae, 6–10 setules in each. Lateral fascicles of setules as in female. Postabdominal claw straight, shorter than in female, with basal pecten consisting of about 10 spines; length of distalmost spines exceeding width of the claw at the spot. Basal spine similar to that of female, but shorter. Limb I with U-shaped copulatory hook. IDL setae 2–3 much thinner than in female, of similar length, armed with thin setulae; male seta straight and thin, slightly shorter than IDL seta 2; seta 1 not present on the drawing ( Elías-Gutiérrez et al. 1997, fig. 15).

Size. In studied material, in instar I juvenile female length was 0.45–0.46 mm, height 0.28 mm; in instar II juvenile female length was 0.59–0.6 mm, height 0.36–0.38 mm; in adult parthenogenetic female length was 0.66– 0.85 mm, height 0.4–0.52 mm. According to Elías-Gutiérrez et al. (1997), length of male 0.5–0.55 mm.

Differential diagnosis. C. dadayi clearly differs from C. aloniceps and C. oklahomensis in presence of a dorsal keel; from C. streletskayae and C. fennicus in normal, narrowing distally basal spine of postabdominal claw and by distalmost marginal denticles of postabdomen of similar size as neighbors; from C. rectirostris in absence of denticles on posteroventral margins of valves and different morphology of IDL; from C. lilljeborgi in morphology of ventral setae of valves and morphology of exopodites III–V; from C. similis in IDL setae 2–3 armed with spines and by distalmost marginal denticles of postabdomen of similar size as neighbors; from C. australis in a normal morphology of lateral head pores and truncated rostrum; from C. uncinatu s and C. vietnamensis in (1) a truncated rostrum, (2) IDL setae 2–3 with less developed basalmost denticle and more developed distal portion and (3) pecten of postabdominal claw composed of less than 10 robust spines.

Notes. Studied specimens differ from type material redescribed by Frenzel (1987) in a less truncated rostrum, but rostrum shape is rather variable in at least some species of Camptocercus , like C. rectirostris (see Smirnov 1998). Also, the specimen in Frenzel's drawing is obviously distorted. Specimens from Paraguay, described by Daday (1905) , have intermediate state of rostrum morphology.

Distribution. Mexico, Central and South America.

Figures

FIGURE 6. Camptocercus dadayi Stingelin, 1913 from Mexico, a channel at El Guao lagoon: A – B, juvenile females of instar I and II. C – M, parthenogenetic female. C, lateral view. D, ventral margin of valve. E, posteroventral angle of valves. F, head. G, abdomen. H – I, postabdomen. J, postanal margin of postabdomen. K, postabdominal claw. L, antennule. M, antenna.

FIGURE 7. Camptocercus dadayi Stingelin, 1913, parthenogenetic female from Mexico, a channel at El Guao lagoon. A, lateral view. B, ventral view. C, dorsolateral view. D, setae from ventral margin of valves of posterior group. E, head pores. F, abdomen and postabdomen. G, distal portion of postabdomen. H, postabdominal claw.

FIGURE 8. Camptocercus dadayi Stingelin, 1913, parthenogenetic female from Mexico, a channel at El Guao lagoon. A – B, labrum. C, limb I. D, IDL and ODL of limb I. E, limb II. F, exopodite of limb III. G, inner portion of limb III. H, exopodite of limb IV. I – J, inner portion of limb IV. K, exopodite of limb V. L, inner lobe of limb V.