Lappodiamesa omelkoi Makarchenko et Makarchenko, 2013

Makarchenko, Eugenyi A. & Makarchenko, Marina A., 2013, A new species of Lappodiamesa Serra-Tosio (Diptera: Chironomidae: Diamesinae) from the Russian Far East, with a key to known species of the genus, Zootaxa 3709 (6), pp. 591-596 : 591-595

Lappodiamesa omelkoi Makarchenko et Makarchenko , sp. n.

( Figs. 1–19 )

Material. Holotype: male, reared from pupa. RUSSIA. Unnamed stream (N 4341'675", E 13209'293"), Mountain- Taiga Station of the Far Eastern Branch Russian Academy of Sciences , Gornotaezhnoe Village , Ussuryisky Region, Primorye Territory, 6.V. 2013, leg. E. Makarchenko & T. Tiunova . Paratypes: 1 male reared from pupae, 2 larvae, same data as holotype except 28.IV. 2013, leg. E. Makarchenko ; 1 mature pupa, same data as holotype except 23. V. 2012, leg. E. Makarchenko & M. Makarchenko ; 2 larvae, 1 male reared from pupa, 3 mature pupae, 1 pupa reared from larva, 1 pupal exuviae, 1 mature larva, same data as holotype except 6. V. 2013, leg. E. Makarchenko & T . Tiunova .

Adult male (n = 2). Total length 3.9–4.3 mm. Wing length 2.52–2.60 mm. Total length/wing length 1.55–1.65. Coloration: body uniformly brown to dark brown, wings grey or grayish.

Head. Eyes pubescent, with dorso-median prolongations. Temporal setae (on each side) 13–21 verticals and 11–13 postorbitals. Clypeus with 5–7 setae. Antenna with 13 flagellomeres and well-developed plume; 13 th flagellomere with 1–2 subapical setae; AR 1.82–2.04. Lengths (µm) of palpomeres 1–5: 28, 72–84, 80–120, 88– 104, 120–156; third palpomere with sensilla chaetica in distal part.

Thorax. Antepronotum with 5–6 lateral setae; distance between antepronotal lobes about 40 µm. Acrostichals 0–1 (in middle part of scutum), dorsocentrals 9–14, prealars 7–11. Scutellum with 20–27 setae in 2 rows.

Wing. Anal lobe well developed. Squama with 27–34 setae. R with 14–15 setae, R 1 with 2–3 setae, R 4+5 with 2– 3 setae subapically. Costal extension 72 µm long.

Legs. Spur of fore tibia 78 µm long. Spurs of mid tibia 36 µm and 48 µm long, of hind tibia 66 µm and 24 µm long. Hind tibial comb with 7–9 setae. Fore ta 1 with 2 apical pseudospurs, ta 2 with 0–1 pseudospurs. Mid ta 1 with 8– 11 pseudospurs, ta 2 with 2–4 pseudospurs. Hind ta 1 with 10–12 pseudospurs, ta 2 with 2–4 pseudospurs. Pulvilli small and needle-shaped. For length and proportions of leg segments see Table 1.

Hypopygium ( Figs. 1–5 ). Tergite IX with 11–18 setae in two groups. Anal point simple, thin and narrowed from base to tip, 100–104 µm long ( Figs. 1–2 ). Laterosternite IX with 12–15 setae on each side. Transverse sternapodeme 128–144 µm long and 8–12 µm wide, without oral projections. Medial aedeagal lobes sclerotized and club-shaped, 92–96 µm long; phallapodemes weakly sclerotized, rod-shaped with widened and dark subapical part, 80–104 µm long, sometimes curved ( Figs 4–5 ). Gonocoxite 260–272 µm long; basally with rounded superior volsella covered with 6–10 strong setae, inferior volsella weakly delineated. Gonostylus 120–140 µm long, with preapical crista dorsalis; megaseta 10–12 µm long. Pars ventralis weakly observable.

Pupa (n = 4). Total length 4.50–4.75 mm. Coloration light-brownish. Exuviae transparent, with beige tint. Abdomen with dark brown apophyses.

Cephalothorax. Frontal apotome without frontal tubercles or frontal setae. Median two antepronotals and one lateral antepronotal seta hair-like, 40–72 µm long. Precorneal setae lengths (µm): Pc 1 32–40, Pc 2 56–80, Pc 3 40–56. Distance between Pc 1 and Pc 2 16–26 µm; distance between Pc 2 and Pc 3 12–22 µm. Thoracic horn absent. Dorsocentrals 4; distance between Dc 1 and Dc 2 120 µm; distance between Dc 2 and Dc 3 136–180 µm; distance between Dc 3 and Dc 4 144–288 µm.

Abdomen. Tergite I with weak median shagreen in 2 groups. Tergites II–VII with anterior, median, lateral and posterior shagreen, as in Figs. 6–8 ; in posterior part spinules of shagreen often larger. Surface near apophysis of tergites VII–VIII with net-like shagreen ( Fig. 9 ). Tergite VIII of male with same shagreen as in tergites II–VII, but female with shagreen in anterior part ( Fig. 7 ). Tergite IX without shagreen. Sternite I without shagreen. Sternites II–VIII with weak shagreen of small spinules. Segment I with 4 pair of hair-like lateral setae 50–60 µm long. Segments II–VII with 4 pairs of lateral setae of different size: length of L 1–3 c. 100 µm, length L 4 40–100 µm. Segment VIII with 4 pair of lateral setae 40–60 µm long and displaced dorsomedial ( Figs. 7–8 ); sometimes lateral setae of tergite VIII bifid. Anal lobe 400–512 µm long, without apical tubercle or spines, with rugose outer edge in subapical part. Male genital sack not longer than anal lobe. Anal macrosetae 224–240 µm long, with folded apical part.

Fourth instar larva (n = 5). Colouration brownish. Total length 4.8–6.7 mm.

Head. Head capsule 0.37–0.40 mm long, dorsal surface light-brownish, lateral parts pale, postoccipital margin dark brown or black, moderately wide; distance between tentorium branches light. Labrum with simple S I –S IV setae; pecten epipharyngis consisting of 9 elongate scales. Premandible distally with 5 teeth ( Figs. 10–11 ). Antenna with 5 segments. Length of antennal segments (µm): 56–68, 10–12, 8–10, 4, 4. AR 2.0–2.43. Large ring organ and seta situated in basal 1/8 of first segment; antennal blade ending near apex of fourth segment ( Figs. 12–14 ). Mandible dark brown, with 5 subequal teeth, seta interna with 22–30 branches, seta subdentalis short ( Fig. 16 ). Mentum with 1 median and 8–9 lateral pairs of teeth; median tooth little wider and higher than first two lateral teeth; group of five median teeth lighter than other teeth ( Figs. 15, 19 ). Sometimes mature larvae with destroyed median part of mentum and median teeth effaced. Only in uncurled mentum all the 8-9 teeth are visible ( Fig. 18 ).

Abdomen. Body segments with some dorsal and ventral setae not more than 80 µm long; segments I–VII with 3 pairs of lateral setae 68–120 µm long; segment VIII with 1 pair lateral setae, segment IX without lateral setae. Procercus dark brown, 32–44 µm long, 28–40 µm wide, with 7–9 anal setae 560–608 µm long and 2 short and thin lateral setae ( Fig. 17 ). Supraanal setae 200–336 µm long. Posterior parapods 400–448 µm long, 112–128 µm wide, in basal part ventral with pair of hair-like setae 124–160 µm long. Anal tubules cone-shaped, subequal in size 160– 208 µm long.

Diagnosis. Lappodiamesa omelkoi is closely related to the Nearctic species L. boltoni in all life stages but may be easily separated from other known species of the genus by the shape of gonostylus and anal point of male hypopygium, by arrangement of pupal tergite shagreen, by the structure of larval mentum and the number of scales on pecten epipharingis, as well as by some other characters given in the key below.

Etymology. We dedicate the name to Dr. Mikhail M. Omelko, the entomologist from Mountain-Taiga Station of the FEB RAS, and thank for providing us with information on sampling site, where several new species of chironomids and may-flies were collected.

Distribution and biology. Lappodiamesa omelkoi is known only from the type locality. in unnamed stream near Mountain-Taiga Station of the FEB RAS in the southern part of Primorye Territory of the Russian Far East.

Pupae and larvae were collected in detritus with sand sampled from stream. During sampling in 2013 the water temperature ranged between 1.7–7.1°C, pH 7.8, depth 5–15 cm. One mature pupa was collected in 2012 (water temperature 12.4 °C).

Figures

FIGURES 1–5. Male of Lappodiamesa omelkoi sp. n. 1–2, hypopygium in dorsal view; 3, gonostylus; 4–5, transverse sternapodeme, aedeagal lobes, phallapodemes and superior volsellae. Scale bars 50 µm.

FIGURES 6–19. Pupa (6–9) and larva (10–19) of Lappodiamesa omelkoi sp. n. 6, tergite IV; 7, tergite VIII and anal segment of female; 8, tergites VII–VIII and anal segment of male; 9, detail of shagreen near apophysis of tergite VII; 10–11, premandible; 12, antenna; 13, antennal blade; 14, ring organ and seta in basal part of 1st antennal segment; 15, 19, normally developed mentum; 16, mandible; 17, procercus; 18, uncurled mentum with disclosed median teeth. Scale bars are as follows: Figs. 6–8: 200 µm; Fig. 9: 50 µm; Figs. 10–19: 40 µm.