Chironomus salinarius Kieffer, 1915

Orel, Oksana V., Istomina, Albina G., Kiknadze, Iya I., Zinchenko, Tatiana D. & Golovatyuk, Larisa V., 2014, Redescription of larva, pupa and imago male of Chironomus (Chironomus) salinarius Kieffer from the saline rivers of the Lake Elton basin (Russia), its karyotype and ecology, Zootaxa 3841 (4), pp. 528-550 : 533-537

Chironomus salinarius Kieffer, 1915

( Figs 2–18 )

Chironomus salinarius Kieffer in Thienemann, 1915: 451; Goetghebuer (1928: 62); Thienemann, Strenzke (1951: 15); Strenzke (1959: 22, fig. 11); Keyl & Keyl (1959: 1); Keyl (1962: 464); Linevich & Erbaeva (1971: 156, figs 73–80); Michailova (1973: 348), ( 1980: 141), (1989: 108); Pinder (1978: 114, fig. 145D); Sasa (1978: 20, figs 57–63); Grinchuk (1979: 44), ( 1984: 751); Pankratova (1983: 139); Ali & Majori (1984: 17); Webb & Scholl (1985: 353); Webb, Scholl & Ryser (1985: 373); Ceretti et al. (1987: 289); Chun (1989: 37); Yoon & Chun (1992: 1); Ali et al. (1994: 35); Drake & Arias (1995: 195); Sasa (1996: 94, fig. 8); Mirabdullayev et al. (2004: 101); Suemoto et al. (2004: 107); Fuentes et al. (2005: 289); Kim et al. (2005: 21); Ree & Yum (2006: 63, fig. 1); Gascon et al. (2007: 419); Ponti et al. (2007: 79); Marchini et al. (2008: 1076); Cartier et al. (2010: 637); Istomina et al. (2012: 55, figs 16–21); Kasatkina & Shubin (2012: 95).

Material. Male, pupa, larva, Russia, Volgograd region, the Lake Elton basin, the Chernavka River, 29.VI.2012, leg. L. Golovatyuk (rearing); male, pupa, larva, the same location, 6.VII.2012, leg. L. Golovatyuk (rearing); male, pupa, larva, the same location, 7.VII.2012, leg. L. Golovatyuk (rearing).

Diagnostic characters. The imago males of C. salinarius Kieffer can be separated from some species by following combination of features: dark brown or black colour midges, total length 5.0– 6.2 mm, wing length 2.40–3.25 mm, AR 2.84–3.20, LRP1 1.36–1.40, BRP1 5.0–7.9, Ac 18–22, Dc 19–25, Pa 6–7, Scts 17–35, Sq 15–21, legs yellowish brown, except to dark brown proximal and apical ends of femur, proximal ½ and apical end of tibia, ta1–5 gradually darken to end, tergite IX with 6–8 median setae, anal point expanded in apical third, superior volsella E-type, gonostylus the widest at proximal third. The pupa differs following combination of features: total length 6.0–7.0 mm, segment I with anterior and posterolateral Pedes spurii B; tergite VII in proximal half part with two patches of shagreen; tergite VIII with two patches of shagreen medially; tergites V–VII laterally with longitudinal rows of spinules; tergites V–VI with posterior-lateral patches of spines. The larva can be distinguished from the other members of the salinarius-type larva by following features: AR 1.85–2.15, L1 68–85 µm, L 2 17–22 µm, blade reached to the segment 5, ring organ situated in the proximal 2/3 basal segment; pecten epipharyngis with 17–24 teeth; anterior margin of the base maxilla with 1–2 tubercles; mandible II-type, with 1 yellowish dorsal tooth, dark brown apical and 3 inner teeth; type of mentum by the characters of the median teeth—I/II; type of mentum by the degree of development of the 4th lateral teeth—I; ventromental plate with 57–69 short striae, not reached inner spines series, type of strial termination IIIA, VmPR 0.36–0.45. VmPSR 1.6–2.4.

Male (n=3). Total length 5.0– 6.2 mm; wing length 2.4–2.5 mm. Total length / wing length 2.08–2.58. Coloration. Thorax and abdomen dark brown or black. Legs yellowish brown, except to dark brown proximal and apical ends of femur, proximal ½ and apical end of tibia, ta1–5 gradually darken to end.

Head. Head width 680 µm. Height of eyes 376–520 µm. HIR 6.07. Frontal tubercles finger-shaped, length 30–36 µm, width 12 µm. Antenna 1320–1386 µm long. Ultimate flagellomere 990–1056 µm long. AR 3.0–3.2. Verticals 22–26. Clypeus with 25–31 setae. Cibarial pump 120–129 µm long, 84–90 µm wide. Maxillary palp 606–657 µm long, lengths of last 4 palpomeres (in µm): 42–60; 147–156; 168–174; 243–270. CP 1.12; Al/Pl 2.00–2.18.

Thorax. Acrostichals 18–22; dorsocentrals 20–25; prealars 6–7; supraalars 1–2. Scutellum with 22–35 setae.

Wing. Length 2.4–2.5 mm, width 0.64–0.68 mm. Veins R, R1 with 41–46 setae, R4+5 with 11–16 setae. Squama with 15–20 setae; brachiolum with 2–3 setae. VR 1.0–1.06.

Legs. Spurs of middle tibia 24 and 30 µm, of hind tibia 24 and 30 µm long. TiR 1.96–2.08. Lengths and proportions of legs as in Table 2 .

Hypopygium ( Figs 2–5 ). Tergite IX with 6 median setae. Lateral tubercles sometimes present on tergite IX. Laterosternite IX with 5–8 setae. Anal point 90–105 µm long, 12–15 µm wide, expanded in the apical 1/3, sometimes the widest at about middle (depends on the position of hypopygium). Transverse sternapodeme 93–111 µm long, without oral projections. Phallapodeme 135–144 µm long. Gonocoxite 180–186 µm long, with 5–6 inner setae. Total length of superior volsella 75–90 µm, with 6–10 basal setae; height of apical finger-shaped part 60–69 µm, width—18–21 µm, base (15–21 µm high, 30–42 µm wide) cover microtrichia (E– type). Inferior volsella 135–144 µm long, with 32–40 setae. Gonostylus 156–165 µm long, 36–39 µm wide, widest at proximal 1/3, with 1 apical seta (15 µm long) and 3–4 subapical inner setae. GsR 4.1–4.6. HR 1.11–1.15.

Pupa (n =3, males). Total length 6.6–7.0 mm.

Cephalothorax ( Figs 6–7 ). Cephalic tubercles conical 63–75 µm long, 45–48 µm wide; frontal setae 66–75 µm long ( Fig 6 ). Base of thoracic horn 78–90 long µm, 45–60 µm wide. Prealar tubercle developed. Pc1 51–54 µm long, Pc2 51–54 µm long; MAps 111–135 µm long; Dc1 45–75 µm long, Dc2 45–90 µm long, Dc3 45–51 µm long, Dc4 48–60 µm long; distance between setae Dc1–Dc 2 10–84 µm, Dc3–Dc 4 18–36 µm, Dc2–Dc3 123–156 µm. Wing sheath length 237–246 µm, width 60 µm ( Fig 7 ).

Abdomen ( Figs 8–12 ) length 5.0– 5.5 mm. Tergites II–VI covered by square shagreen; tergite VII in proximal half part with two patches of shagreen; tergite VIII with two patches of shagreen medially. Tergites V–VII laterally with longitudinal rows of spinules; tergites V–VI with posterior-lateral patches of spines. Anal segment without shagreen, but in posterior part granulose. Hook row with 64–78 hooks; tops of median hooks with 1–5 little teeth ( Fig 8 ). Conjunctives IV/V and V/VI with little spinules, sometimes on conjunctives V–VI spinules absent. Sternite I usually with several spinules laterally; sternite II medially with shagreen and lateral longitudinal rows of spinules; sternites III in proximal part with median path of shagreen and several spinules laterally; sternite IV usually with several spinules laterally; sternites V–VI with posterior-lateral group of spinules; sternites VI–VIII with anteriorlateral group of shagreen. Segment I with anterior and posterolateral pedes spurii B ( Fig 9 ). Segment VIII with single dark brown spur, sometimes spur with three tips, covered by 5–7 dorsal spines ( Figs 11–12 ). Segment II–IV each with 3 L setae, V–VI each with 4 LS setae, VII with 3–4 LS setae, VIII with 5 LS setae. Anal lobe with 65–78 lamelliform setae. Length of anal lobe 400–432 µm, width 416–464 µm. ALR 0.86–1.04. Fourth instar larva (n=3).

Head ( Figs 13–18 ) yellowish brown, length 0.50–0.55 mm, width 0.45 mm, cephalic index (W/L) 0.82–0.90. Frontal apotome 408–440 µm long, 136–176 µm wide. Distance between setae S1– S1 69 –84 µm, S2– S2 96 –114 µm, S3– S3 93 –123 µm, S4– S4 96 –129 µm, S5– S5 96 –129 µm. Antenna 111–123 µm ( Fig. 13 ), length of each segment (in µm): 69–84; 18; 6; 9; 6. AR 1.85–2.15. Maximal width of basal segment 24–27 µm. Ring organ distribute in the proximal 2/3 basal segment; distance from ring organ to base of antenna 24 µm; ROR 2.9–3.5. Blade 42 µm long, reached to the segment 5; accessory blade 12 µm. S I 45 –48 µm long, S II 54 –60 µm long, S III 21 µm long, S IV 6 µm long. Pecten epipharyngis 42–45 µm long, with 17–24 teeth. Premandible 102–105 µm long, with 2 teeth; premandibular seta simple 15–24 µm long ( Fig. 14 ). Mandible 159–180 µm long, 87–99 µm wide; with 1 yellowish dorsal tooth, dark brown apical and 3 inner teeth; length apical tooth 21–24 µm ( Fig. 15 ). Type mandible II (some degree of pigmentation present on 3rd tooth and tooth partly free on lower margin). Seta subdentalis 15–21 µm long. Pecten mandible with 12–14 setae. Mola with 1–3 long spines (15–21 µm). Mandible basally with 8–16 radial grooves. Maxillary palp 24–30 µm long, 15–21 µm wide. Anterior margin of the base maxilla with 1–2 tubercles ( Fig. 16 ). Mentum 141–153 µm wide, central tooth conical 12–16.5 µm, median trifid tooth 27–42 µm wide, distance between first lateral teeth 48–66 µm, distance between second lateral teeth 72–84 µm; distance between the top of first lateral teeth 42–54 µm ( Figs 17 ). Type of mentum by the characters of the median teeth—I/ II; type of mentum by the degree of development of the 4th lateral teeth—I. Ventromental plate 150–168 µm wide and 60–78 µm height ( Fig. 18 ). Distance between ventromental plates 30–48 µm. Ventromental plates with 60–65 striae. VmPR 0.36–0.45. VmPSR 1.6–2.4.

Body. Lateral and ventral tubules absent. Procercus 21 µm height and 12 µm wide.

Figures

FIGURES 2 – 5. Imago male of C. salinarius Kieffer. 2 — hypopygium, dorsal view; 3 — lateral tubercles on tergite IX; 4 — anal point, dorsal view; 5 — superior volsella, dorsal view. Scale bar 100 µm.

FIGURES 6 – 12. Pupa of C. salinarius Kieffer. 6 — frontal apotome; 7 — thorax; 8 — median hooks in the posterior margin of tergite II, lateral view; 9 — tergites I – VI; 10 — tergites VII – IX; 11 – 12 — variability of anal spurs. Scale bar 100 µm.

FIGURES 13 – 18. Larva of C. salinarius Kieffer. 13 — antenna; 14 — labro-epipharyngeal region; 15 — mandible; 16 — anterior margin of base maxilla; 17 — median and 1 – 2 lateral teeth; 18 — mentum and ventromental plate. Scale bar 100 µm.

Tables

TABLE 2. Lengths (in µm) and proportion of legs C. salinarius

P	fe	ti	ta 1	ta 2	ta 3	ta 4	ta 5
P 1	1078–1122	1012–1100	1430–1496	792–836	594–638	528	264–308
P 2	1166–1276	1056–1166	594–682	396–440	286–308	176–220	154
P 3	1320–1408	1320–1430	968–1056	594–616	440–462	264–286	176–198