Smittia solominae Makarchenko, Semenchenko et Palatov, 2024

Makarchenko, Eugenyi A., Semenchenko, Alexander A. & Palatov, Dmitry M., 2024, Smittia solominae sp. nov. (Diptera: Chironomidae: Orthocladiinae), living on ice of high mountain glaciers of the Elbrus Region (North Caucasus), Zootaxa 5415 (4), pp. 561-569 : 562-566

Smittia solominae Makarchenko, Semenchenko et Palatov , sp. nov.

http://zoobank.org/NomenclaturalActs/ 37B17E4B-BAC8-4F65-B567-476C8C7A48BE

( Figs. 1–20 )

Type material. Holotype, adult male, RUSSIA, North Caucasus, Kabardino -Balkarian Republic, Elbrus Region, Bashkara Glacier , collection from ice under stones, alt. 2603 m a.s.l., 1.VIII. 2023, 43.206675 N, 42.723542 E, leg. D. Palatov. Paratypes, 7 adult males, 4 pupae, 8 larvae, the same data as holotype ; 5 adult males, 1 pupa, 7 larvae, the same data as holotype, except Bezingi Glacier near Barankosh alpine site, alt. 2750 m a.s.l., 25.VII. 2022, 43.064789 N, 43.087328 E., leg. D. Palatov ; 4 larvae, the same data as holotype, except Kashkatash Glacier , collection from ice under stones, alt. 2625± 5 m a.s.l., 43.209886 N, 42.683997 E, 23.VII. 2023, leg. D. Palatov.

Derivatio nominis. The species is named after the Russian glaciologist and paleoclimatologist Dr. Olga Nikolaevna Solomina (Institute of Geography, Russian Academy of Sciences), who devoted her entire life to studying the glaciers of the Greater Caucasus.

Description

Adult male (n = 5, except when otherwise stated). Total length 2.0– 3.4 mm. Total length/wing length 0.96– 1.55.

Coloration. Dark brown to black. Wings greyish.

Head. Eyes reniform, hairy. Temporal setae including 4 inner verticals and 5–6 outer verticals. Clypeus with 7–13 setae. Antenna with 13 flagellomeres and normal plume of setae, 148–213 μm long; terminal flagellomere with 1 subapical seta, 36–44 μm long; AR 0.86–0.91. Palpomere length (μm): 20–24, 36, 76–92, 56–72, 80–108. Head width/palpal length 1.5–1.8.

Thorax.Antepronotum with 3–4 ventrolateral setae. Acrostichals 5–6, 4–6 μm long; dorsocentrals 11–16, 72–92 μm long; prealars 4–7, 56–60 μm long. Scutellum with 9–12 setae, 48–68 μm long (in 1 row).

Wing. Length 2.08–2.2 mm, width 0.56–0.58 mm. Costal extension 80–82 μm long. Anal lobe slightly reduced, rounded. Squama without setae. R with 4–7 setae, R 1 with 0–1 seta, R 4+5 without setae. R 2+3 unclearly expressed. Legs. Spur of front tibia 36–64 µm long. Spurs of mid tibia 20–22 µm long. Spurs of hind tibia 44–48 µm and 20–44 µm. Hind tibial comb with ca 16 setae. Length (μm) and proportions of leg segments are as in Table 1 .

Hypopygium ( Figs. 1–8 ). Tergite IX with 4–6 setae, ca 8 µm long, edge of Tergite IX reaches anal point in middle part ( Fig. 8 ). Anal point bare, narrowed distally, finger-shaped ( Figs. 5, 8 ), 120–132 μm long. Laterosternite IX with 1 long setae, 68–73 μm long ( Fig. 1 ). Transverse sternapodeme narrow, wide triangular ( Fig. 2 ). Phallapodeme sclerotized, 76–88 µm long. Gonocoxite 236–248 µm long; inferior volsella flat and broadly triangular, covered with setae and macrotrichia ( Figs. 1, 6 ); superior volsella reduced. Gonostylus 144–148 µm long, in distal quarter with triangular crista dorsalis, small, 8–14 µm height; along the inner edge with 4–6 setae, 12–20 µm long; apex with macroseta, 8–12 µm long ( Figs. 3–4, 6–7 ); HR 1.64–1.68.

Pupa (n=5). Total length 2.7–3.6 mm. Coloration brownish brown ( Fig. 9 ). Exuviae brownish gray.

Cephalothorax. Cephalic area without warts or tubercles. Frontal setae absent. Thorax wrinkled, in anterodorsal and lateral parts slightly granulated. Thoracic horn absent. Precorneal setae lengths (μm): Pc 1 –32–36, Pc 2 –40–60, Pc 3 –28–48. Antepronotum and mesonotum without setae.

Abdomen. Tergite I bare or with some spinules in the back. Tergites II –IX evenly covered with spinules ( Fig. 11 ); sternites V —I X with some shagreen in middle posteriorly. Apophyses absent. Pedes spurii A and B absent. Abdominal setation very weak; lateral setae segments II–VIII only 1 pair, 16–20 μm long. Anal lobe absent. Tergite IX reduced, apically rounded with posterior margin medially indented, without setae. Genital sac of male extending beyond tergite IX, without basal spinules ( Fig. 10 ).

Fourth instar larva (n = 6, except when otherwise stated). Coloration of fixed larvae greenish-bluish, head yellow ( Fig. 20 ). Total length 4.3–5.8 mm (n=10).

Head capsule 262–295 µm long and 230–246 µm wide; postoccipital margin black and narrow. Labral setae S I divided into 3–4 unequal sized branches ( Fig. 12 ); S II simple. Premandible with 2 apical teeth ( Fig. 12 ). Antenna 4 segmented, total length 54–59 µm; length of segments (µm): 25–30, 21–23, 3.3–5, 2.5–3. Antennal blade 26–31 µm long, reaches base of 4 th segment; segment 2 with weak Lauterborn organs; large ring organ with a diameter of 4.5–5 µm is located in distal half of basal segment ( Figs. 13, 17–18 ); AR 0.97–1.17. Mandible dark brown or black in distal part; total length 116–133 µm; with apical tooth and 3 true inner teeth and one false tooth; apical tooth shorter than combined width of 3 inner teeth; seta subdentalis reaches top of lower inner tooth; seta interna with 4–6 terminally serrate branches ( Fig. 16 ). Mentum with 5 pairs of lateral teeth and wide median tooth which has a rounded or ground straight edge and is 3.4–4 times wider than first lateral tooth; ventromental plates weak ( Figs. 14–15 ). Anterior parapods basally fused, with numerous fine spines in basal part and claws at apex. Posterior parapods reduced and bearing simple claws ( Fig. 19 ). Procercus absent; anal tubules slightly reduced but good visible ( Fig. 19 ).

Diagnosis. The adult male of the new species differs from all known representatives of the genus Smittia in the structure of the hypopygium and the following characters. Total length 2.0– 3.4 mm. Wing length 2.08–2.2 mm. AR 0.86–0.91. Acrostichals 5–6, dorsocentrals 11–16, prealars 4–7, scutellars 9–12 setae in 1 row. LR 1 0.44–0.46, BV 1 3.05–3.29, SV 1 4.0–4.10. Tergite IX with 4–6 setae only along edge of anal point in middle part. Anal point bare, narrowed distally, finger-shaped. Transverse sternapodeme narrow, wide triangular. Inferior volsella flat and broadly triangular, covered with setae and macrotrichia; superior volsella reduced. Gonostylus in distal quarter with triangular crista dorsalis; along the inner edge with 4–6 setae; apex with macroseta; HR 1.64–1.68. The pupa and larva are typical for the genus and can hardly be distinguished from other species, for most of which the preimaginal stages of development are still unknown.

Biology and distribution. Currently, adults, pupal and larval stages of S. solominae sp. nov. have been found on two glaciers in the Greater Caucasus mountain range within the Kabardino-Balkaria Republic : Bashkara Glacier (43.206675 N, 42.723542 E, elevation – 2600 m above sea level) and Bezingi Glacier (43.064789 N, 43.087328 E., elevation – 2750 m above sea level). Only larvae have been found on Kashkatash Glacier (43.209886 N, 42.683997 E, elevation – 2610 m above sea level), also within Kabardino-Balkaria ( Figs. 21–22 ).

Thus, the new species inhabits the surface of large valley glaciers in the Central Caucasus at elevations ranging from 2600 m above sea level.

In all cases, S. solominae sp. nov. was found relatively far from the glacier edge, usually several hundred meters away. The larvae, pupae, and adults of this species inhabit spaces beneath large rocks that fall onto the glacier from the surrounding rocky slopes of the valleys. They have been found both on the underside of rocks directly adjacent to the ice and on the surface of the ice beneath the rocks. Adult individuals were not observed flying (possibly due to constant strong winds), although clusters of adults (including mating individuals) were found on the underside of rocks ( Figs. 23–24 ). In some cases, the density of S. solominae sp. nov. adults and pupae on the ice reached 15–20 individuals per square meter, while larvae on the surface of rocks ranged from 0.9–2.4 individuals per square decimeter; however, their distribution on the glacier surface is highly uneven. The larvae are likely algophagous and feed on algae covering the glacier surface and rocks. Their distribution may be related to algal accumulations on the glacier surface. The presence of larvae of different ages, pupae, and adults simultaneously indicates an extended period of emergence for this species. S. solominae sp. nov. individuals were not observed outside the glacier surface. During nighttime, adults did not fly towards specially installed light traps located outside the glacier boundaries. It is possible that adult individuals of this species do not have the ability to actively move, partly due to the constant sub-zero temperatures at the surface.

Figures

FIGURES 1–8. Adult male of Smittia solominae sp. nov. 1, 7, hypopygium in dorsal view; 2, transverse sternapodeme; 3–4, gonostylus; 5, anal point in lateral view; 6, gonocoxite and gonostylus; 8, anal point in dorsal view.

FIGURES 9–20. Pupa (9–11) and larva (12–20) of Smittia solominae sp. nov. 9, abdomen; 10, anal segment; 11, shagreen of tergites; 12, labrum and premandibles; 13, 17, antenna; 14, median teeth of mentum; 15, mentum; 16, mandible; 18, 2–4 antennal segments; 19, anal segment; 20, total view of larva. Scale bars: 20 μm.

FIGURES 21–24. Habitat of Smittia solominae sp. nov. on Bashkara (21) and Bezingi (22) Glaciers. 23, larvae crawling on the ice surface; 24, larvae on the underside of a rock lying on the glacier.