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 : 30-31

Diamesa sp. Himalaya2

( Fig. 3C )

Female imago (n = 1)

Head: Antenna with ultimate flagellomeres lost. Pedicel with 1 seta. Dorsal sensilla coeloconica on flagellomeres 1–3. Coronal suture complete. Number of temporal setae 34, including 7 postorbitals; frontals and orbitals slightly separated from remaining verticals. Eyes hairy, fairly small and moderately projecting dorsomesally. Clypeus 130 m long, 170 m wide, without setae. Palps short; lengths of palpomeres (µm): 33, 55, 115, 72, 77. Second palpomere with or without distal campaniform sensilla. Third palpomere with sensory pit. Tentorium tube­like without anterolateral projection.

Thorax: Antepronotum with 11 lateral setae. Acrostichals absent. Dorsocentral setae, 10, in 1 row, 11 prealars behind callus, 36 scutellars. Protuberance of epimeron II with 14 setae.

Wing: Length 4.49 mm. VR 0.94. Punctuation of membrane visible with 125x magnification. Costa moderately produced beyond R4+5. R with 15 setae. R1 with 12 setae and 3 sensillae campaniformia. R2+3 with 1 sensillae campaniformia. R4+5 with 11 setae and 2 sensillae campaniformia. Alula without setae. Squama with marginal fringe of about 45 setae.

Legs: Comb of hind tibia with 19 setae. Tarsi 1–3 respectively with following numbers of apical/preapical pseudospurs: 2/8, 2/2, 2/1 on p1; 2/21, 2/19, ­/­ on p2; 2/25, 2/10, 2/2 on p3. Hind leg with about 170 sensilla chaetica distributed from 0.14 to 0.95 on in ta1. Ta4 cordiform.

fe ti ta1 ta2 ta3 ta4 ta5 LR BV SV p1 1630 1748 1087 483 313 123 189 0.62 4.03 3.11 p2 1890 1772 851 407 ­ ­ ­ 0.48 ­ 4.31 p3 2008 2055 1158 644 455 133 189 0.56 3.67 3.51 Genitalia ( Fig. 3C ): Sternite VIII with 12 or 13 setae on each side; caudolateral margin with deep incision near gonocoxite IX. Gonocoxapodeme distinct and running almost to anterior margin of genital chamber. Gonapophysis VIII with caudomesally projecting flap covering most of ventrolateral lobe. Seminal capsules large, ovoid, with short neck; capsule surface with weak granulation. Seminal ducts relatively long. Gonocoxite IX with massive rounded projection bearing close to 30 long setae. Tergite IX completely divided into 2 narrow plates, each with 10 setae. Segment X with small, ventrally directed protrusion. Cerci more or less oval in lateral view.

Remarks: The short palps, the relatively small clypeus which is devoid of setae, and the massive projections of the gonocoxites are distinctive features of this species. Sensilla chaetica distributed nearly to the distal end of ta1 is also unusual in Diamesa . Spermathecae of similar size have previously been observed only in the Diamesa dampfi group ( Willassen & Serra­Tosio 1988). Characteristics of the head, including the tubelike tentorium, indicate that the male of Diamesa sp. 2 has short antennae. I know of no likely candidates among described species and suggest that males of this species remain undiscovered.

Material studied: China: Tibet, Rongbuk, 5000 m asl., 8– 10.7 .93, leg T.Solhøy, det. E.Willassen, EW216 ( IZAS).

Genetics: Genbank accession number AM 051229 , 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.