Pseudodiamesa, Goetghebuer, 1939

Makarchenko, Eugenyi A., 2022, Redescription of two little-known Palaearctic species of Pseudodiamesa Goetghebuer (Diptera: Chironomidae: Diamesinae), Zootaxa 5092 (5), pp. 596-600 : 598-600

Pseudodiamesa (s. str.) venusta Makarchenko

( Figs. 6–13 ) Pseudodiamesa (s. str.) venusta Makarchenko, 1984: 62; Ashe & O’Connor 2009: 306.

Material examined. Holotype: adult male, Mongolian People’s Republic , Khubsugul Lake basin, mouth of Khoroo-gol River, neighborhood of the Turtu Village, 3.VIII.1979, leg. E. Erbayeva. Paratypes: 3 adult males, same data as holotype, except 3–6.XIII.1979, leg. E. Erbayeva ; 1 adult male, same data as holotype, except 14.XII.1980, leg. E. Erbayeva.

Adult male (n = 4).

Total length 6.1–7.3 mm. Wing length 5.4–5.5 mm. Total length/wing length 1.1–1.3.

Coloration. Head, thorax, legs, and abdomen dark brown to black; antennae brown to dark brown; wings greyish.

Head. Eyes bare and extended dorsomedially. Temporal setae including 14–20 preoculars, 12–16 verticals and 14–20 postorbitals. Clypeus with ca 40–60 setae. Antenna with 13 flagellomeres and developed plume, setae of which 459–1190 μm long; pedicel without setae; terminal flagellomere with 1 subapical setae 58–60 μm long; AR 4.0–4.8. Palpomere lengths (in μm): 40–48; 162–189; 232–248; 228–235; 244–252. Palpomere 3 distally with sensilla capitata (diameter 18–20 μm). Palpomeres 1–5 length/head width 0.94–0.97.

Thorax. Antepronotum with 26–29 lateral setae. Acrostichals absent, dorsocentrals 52–54 (in 2 rows in anterior 2/3 and in 3–4 rows in posterior 1/3), prealars 40–53 (in 2–3 rows), scutellars ca 80–90.

Wing. Length 5.4–5.5 mm; width 1.2–1.3 mm. Membrane without setae. R and R 1 with 11–19 setae; R 4+5 with 0–3 setae on apex. RM length/MCu length 3.1–4.0. Anal lobe developed, outline rounded. Squama with ca 60–80 setae, 139–180 μm long, in 2–3 rows. VR 1.0–1.02.

Legs. Spur of fore tibia 152–189 μm long; spurs of mid tibia 96–118 μm and 104–118 μm; of hind tibia 156–160 μm and 100–109 μm long. Hind tibial comb with 14–18 setae. Lengths and proportions of leg segments as in Table 2.

Hypopygium ( Figs. 6–13 ). Tergite IX with 30–32 setae on each side, 40–76 μm long. Anal point in most specimens with a narrow seta-like distal part ( Figs.6–8 ), and in only one male it is wide at the base and tapering to pointed apex ( Fig. 9 ), 140–172 μm long. Laterosternite IX with 12–16 setae. Gonocoxite 376–392 μm long; basal lobe large, rounded, with some long setae on the surface (Figs. 6,10, 12). Gonostylus 240–292 μm long, in dorsal view wide in basal half, and narrower finger-like in the distal half (Figs. 6,10, 12); shape in ventral view as in Fig. 11 ; megaseta absent. HR 1.34–1.57. Transverse sternapodeme arc-shaped, 296–308 μm long and 36–40 μm wide, without oral projections ( Fig. 13 ). Lateral aedeagal lobe of phallapodeme 220–288 μm long, with wide basal 1/3 and narrow distal 2/3, slightly curved and elongated in rounded apex ( Fig. 13 ).

Hypopygium ( Figs. 6–13 ). Tergite IX with 30–32 setae on each side, 40–76 μm long. Anal point in most specimens with a narrow seta-like distal part ( Figs.6–8 ), and in only one male it is wide at the base and tapering to pointed apex ( Fig. 9 ), 140–172 μm long. Laterosternite IX with 12–16 setae. Gonocoxite 376–392 μm long; basal lobe large, rounded, with some long setae on the surface (Figs. 6,10, 12). Gonostylus 240–292 μm long, in dorsal view wide in basal half, and narrower finger-like in the distal half (Figs. 6,10, 12); shape in ventral view as in Fig. 11 ; megaseta absent. HR 1.34–1.57. Transverse sternapodeme arc-shaped, 296–308 μm long and 36–40 μm wide, without oral projections ( Fig. 13 ). Lateral aedeagal lobe of phallapodeme 220–288 μm long, with wide basal 1/3 and narrow distal 2/3, slightly curved and elongated in rounded apex ( Fig. 13 ).

Pupa and larva unknown.

Remaks. I include this species in the nivosa group. In the original description ( Makarchenko 1984), a mistake was made in indicating the terminal spine on the gonostylus. An analysis of the gonostylus of all available specimens showed that one of the setae near the apex was taken as a short terminal spine. Also, there was no information on the shape and structure of the transverse sternapodeme and there were inaccuracies in the number of setae and measurements of some parts of the male adult. P. (s. str.) venusta differs from other members of the genus mainly in the structure of the hypopygium, namely in the shape of the gonostylus which is wide in the basal part and finger-shaped in the distal part, as well as in the shape and structure of the gonocoxite, the anal point, and other features given in the redescription.

Distribution. Known only from type locality in Khubsugul Lake basin ( Mongolia).

Figures

FIGURES 6–13. Male of Pseudodiamesa (s. str.) venusta Makarchenko. 6, hypopygium in dorsal view; 7–9, anal point; 10, 12, gonocoxite and gonostylus in dorsal view; 11, gonostylus in ventral view; 13, transverse sternapodeme and lateral aedeagal lobes.