Diamesa

Willassen, Endre, 2005, New species of Diamesa (Diptera: Chironomidae) from Tibet: conspecific males and females associated with mitochondrial DNA, Zootaxa 1049, pp. 19-32 : 28-30

Diamesa sp. Himalaya1

( Figs. 3A–B )

Female imago (n = 2)

Head: Antenna with 7 flagellomeres. AR 0.50–0.53. Pedicel with 2 setae. Dorsal sensilla coeloconica on flagellomeres 1–3. Coronal suture distinct. Temporal setae weak, 32–36 in number including 11–13 postorbitals, frontals slightly separated from remaining temporals. Eyes hairy, moderately projecting dorsomesally. Clypeus 123–133 long, 123–133 wide, with 11–16 setae. Lengths of palpomeres (µm): 38, 76, 109, 118, 241. Second palpomere with distal campaniform sensilla. Third palpomere with sensory pit. Tentorium with conspicuous anterolateral projection.

Thorax: Antepronotum with 6–9 lateral setae. Acrostichals absent. Dorsocentrals 9–11 in 1 row, 7–9 prealars behind callus, 39–41 scutellars. Protuberance of epimeron II with 4–6 setae.

Wing: Length 3.14–3.19 mm. VR 0.85–0.89. Punctuation of membrane visible with 125x magnification. Costa moderately produced beyond R4+5. R with 12 setae. R1 with 13 or 14 setae and 2 sensillae campaniformia. R2+3 with 2 sensillae campaniformia. R4+5 with 10 or 11 setae and 4–6 sensillae campaniformia. Alula with 7 or 8 setae. Squama with marginal fringe of about 32–35 setae.

Legs: Comb of hind tibia with 13 setae. Tarsi 1–3 respectively with following numbers of apical/preapical pseudospurs: 2/0, 2/0, 0/0 on p1; 2/10, 2/2, 0/0 on p2; 2/14, 2/4, 0/0 on p3. Hind leg with dense sensilla chaetica distributed from 0.08 to 0.63 on in ta1. Ta4 cordiform.

Genitalia ( Figs. 3A–B ): Sternite VIII with 16–20 setae on each side. Gonocoxapodeme fairly distinct, with caudally displaced separate part running near posterior margin of gonapophysis. Gonapophysis VIII with flap composed of 2 parts, a mesal part with acute projection, and a lateral tonguelike lobe separated by rugulose cavity near base of ventrolateral lobe. Seminal capsules with short, sclerotised neck, capsule surface with weak granulation. Seminal ducts relatively short. Gonocoxite IX with 26–28 setae distributed from base to apex over longitudinal ridge; projection at apex relatively weak. Tergite IX deeply divided into 2 plates, each with 11 or 12 setae and a knoblike projection posterolaterally. Segment X with prominent protrusion directed slightly anterolaterad. Cerci somewhat boot­shaped in lateral view.

Remarks: The female genitalia of this species are unique but the specimens cannot at present be associated with any males of Diamesa . I refrain from describing it as a new species because there are several possible candidates of Himalayan Diamesa with unknown females. The concave margin of the gonapophysis is particularly distinctive. It makes the flap appear more or less with two pointed lobes. The somewhat rugulose area between these lobes extends to a cavity beneath the flap and may fit the ventral projection of the cerci during oviposition. The characteristic shape of the cerci seems similar to a species described ( Tokunaga 1966:fig.7b) from Afghanistan as Diamesa sp. near confluens Kieffer.

Material studied: China: Tibet, Rongbuk, 7.Jul. 1993, leg. T. Solhøy, det. E.Willassen, EW70, 1 female; China: Tibet, Rongbuk, water trap, 8–10.7 1993, leg. T. Solhøy, det. E. Willassen, EW96 ( IZAS).

Genetics: Genbank accession numbers AM 051227 –28, mitochondrial COII gene for cytochrome oxidase subunit II.

Figures

FIGURES 3 A – C. Diamesa spp., female genitalia. A – B, Diamesa sp. Himalaya 1 in ventral and lateral view. C, Diamesa sp. Himalaya 2 in ventral view.