Diamesa solhoyi, Willassen, Endre, 2005

Willassen, Endre, 2005, New species of Diamesa (Diptera: Chironomidae) from Tibet: conspecific males and females associated with mitochondrial DNA, Zootaxa 1049, pp. 19-32 : 22-25

Diamesa solhoyi new species

( Figs. 1A–E )

Type material: Holotype male labelled: China: Tibet, Rongbuk, 5000 m a.sl., 10.Jul. 93, leg. T. Solhøy, det. E.Willassen, EW41. Paratypes with same locality as holotype except: 7.Jul.1993, EW69, 1 female; 8– 10.7 .93, EW164, 1 female; 8– 10.7 .93, 1 female. All specimens in Academica Sinica, Zoological Institute, Beijing, China.

Etymology: This species is named after Torstein Solhøy, University of Bergen, who collected the specimens.

Genetics: Genbank accession numbers AM 051230 –32, mitochondrial COII gene for cytochrome oxidase subunit II.

Male imago (n = 1)

Head: Flagellomeres lost. Antennal pedicel large, with 3 setae. Eyes hairy, moderately projecting dorsomesally. Coronal suture complete. Temporal setae weak and transparent, including 18–20 verticals and six postorbitals. Clypeus 152 m long, 143 m wide; with 9 setae. Palps partly lost. Tentorium ( Fig. 1A ) with conspicuous anterolateral projection.

Thorax damaged in DNA preparation.

Wing: Length 3.98 mm. VR 0.85. Membrane without setae, punctuation of microtrichia distinct at 100x magnification. Costa produced beyond R4+5. R with 20 setae. R1 with 14 setae and 2 sensillae campaniformia. R2+3 with 2 sensillae campaniformia. R4+5 with 6 setae and 3 sensillae campaniformia. Alula without setae. Squama with marginal fringe of about 40 setae.

Legs: Comb on ti3 with 17 setae. Tarsi 1–3 respectively with following numbers of apical/preapical pseudospurs: 2/6, 2/0, 2/0 on p1; 2/13, 2/6, 2/1 on p2; 2/14, 2/6, 2/1 on p3. Hind leg with about 45 sensillae chaetica distributed from 0.3 to 0.6 of ta1.

Hypopygium ( Fig. 1B–C ): Sternapodeme trapezoid with concave anterior margin, pigmentation weak. Pars ventralis long and broad, basal ¾ with microtrichia. Aedeagal lobes visible as faint hyaline plates with rounded, weakly pigmented margins. Basal plate of gonocoxite with blunt caudal projection reaching superior volsella; ventromesal surface with long microtrichia. Basimedial setal cluster well developed, slightly directed anteriad; base somewhat prolonged caudally to ledge with marginal setae. Superior volsella somewhat orthoclad­like, nearly devoid of microtrichia, but with few weak setae dorsally and ventrally. Medial field well delineated; with dense microtrichia, but with setae near ventral margin only. Gonostyli massive with distal constriction, apex acutely pointed with 1 megaseta. Tergite IX divided into 2 protrusions, each with about 20 weak setae. Tergal bands inconspicuous. Anal point inserted below tergal protrusions; base broad and triangular, distal part slender with indication of longitudinal ridge and with setiform sensilla at apex.

Female imago (n = 2)

Head: Antenna with 7 flagellomeres. AR 0.28–0.39. Scape occasionally with 1 seta. Pedicel with 2 or 3 setae. Dorsal sensilla coeloconica on flagellomeres 1–3. Coronal suture distinct. Number of temporal setae 34–46, including 13–14 postorbitals. Eyes hairy, moderately projecting dorsomesally. Clypeus 143–160 long 166–180 wide, with 12–15 setae. Lengths of palpomeres (µm): 47–57, 57–114, 162–180, 152–199, 238–322. Second palpomere with dorsodistal campaniform sensilla. Third palpomere with sensory pit. Tentorium with conspicuous anterolateral projection.

Thorax: Antepronotum with 14–23 lateral setae. Acrostichals absent. Dorsocentrals 14–17 in 1 row except anteriorly, 11–13 prealars behind callus, about 45–50 scutellars. Protuberance of epimeron II with 3–10 setae.

Wing: Length 4.32–4.56 mm. VR 0.86–0.88. Punctuation of membrane distinct at 40x magnification. Costa moderately produced beyond R4+5. R with 21 or 22 setae. R1 with 19–26 setae and 2 sensillae campaniformia. R2+3 with 2 or 3 sensillae campaniformia. R4+5 with 18–21 setae and 3 or 4 sensillae campaniformia. Alula with 7–9 setae. Squama with marginal fringe of about 55 setae.

Legs: Comb of hind tibia with 17 setae. Tarsi 1–3 respectively with following numbers of apical/preapical pseudospurs: 2/8–13, 2/0–4, 2/0 on p1; 2/14–16, 2/7, 2/0–2 on p2; 2/ 20–22, 2/8, 2/4 on p3. Hind leg with about 350 or more sensilla chaetica distributed from 0.09–0.1 to 0.70–0.74 on in ta1. Ta4 cordiform.

Genitalia ( Fig. 1D–E ): Sternite VIII with 14–17 setae on each side, gonocoxapodeme fairly distinct. Gonapophysis VIII with slightly elevated ridge and weak flap that barely covers base of ventrolateral lobe. Seminal capsules with short, sclerotised neck, capsule surface with weak granulation. Seminal ducts relatively short. Gonocoxite IX with thumblike projection curving mesad, 16–19 setae mainly on projection. Tergite IX deeply divided into 2 protrusions, each with about 16 or 17 setae near posterior and lateral margin. Segment X more or less concealed by projection of GcIX, posterolateral protrusion somewhat oval in lateral and triangular in ventral view. Cerci ear­shaped in lateral view.

Remarks: Males of D. solhoyi may be readily identified by the unique combination of genitalic characters. Although the flagellomeres are lost in the single available male specimen, the size of the pedicel and the conspicuous anterolateral projection of the tentorium ( Fig.1A ) indicate that the male antennae are normal sized with 13 flagellomeres.

Females may be recognised by the thumb­shaped gonocoxite IX, which has a roughly trapezoid profile in lateral view.

Figures

FIGURES 1 A – E. Diamesa solhoyi new species. A, male tentorium. B, male genitalia in dorsal view. C, ventral view of pars ventralis (pv), basal plate (bp), basimedial setal cluster (bs) and aedeagal lobe (al). D, female genitalia in lateral view. E, female genitalia in ventral view. Scale bars (C – D) are 250 µm.