Chersodromia flavicaput, Grootaert, Patrick, Cumming, Jeffrey & Shamshev, Igor, 2007

Grootaert, Patrick, Cumming, Jeffrey & Shamshev, Igor, 2007, Non-marine Chersodromia Walker from Southeast Asia and Papua New Guinea (Diptera, Empidoidea, Hybotidae), Zootaxa 1661, pp. 55-61 : 56-59

Chersodromia flavicaput sp. nov.

( Figs. 1–9 )

Diagnosis. Occiput pale yellowish, almost white. No distinct vertical bristles. Three pairs of acrostichals. Hind tibia with 5 long bristles in apical half.

Description. Male. Body length 1.30–1.44 mm, wing length 1.1–1.2 mm. Head completely pale yellowish in ground-colour, almost white, including frons, occiput, face, genae, palpi and proboscis; eyes contrastingly black, ocellar triangle brown. Frons broadly triangular; in front as wide as antennal pedicel, but quickly widening towards ocellar triangle. Eyes touching on face, with ommatidia enlarged on lower half of eye. Anterior ocellars long (longer than basal antennal segments combined), brown; posterior ocellars half as long. No vertical bristles distinct from other postoculars. Gena broad. Occiput somewhat concave above neck. Antenna ( Fig. 1 ) with scape and pedicel yellow, postpedicel brownish; pedicel ventrally with 1 long brown bristle; postpedicel smaller than pedicel; style at least 4 times as long as pedicel and postpedicel combined. Palp small, white, with 1 brown terminal bristle and some concolorous hairs.

Thorax yellow in ground-colour, with dark brown bristles and hairs; scutum on anterior half with brown median vitta and on posterior half with concolorous, large, lateral patch meeting median vitta; katepisternum (= sternopleuron) and meron (= hypopleuron) with dark brown patch. Postpronotal lobe with 1 long inclinate bristle. Mesonotum with 1 short presutural supra-alar, 2 notopleurals, 2–3 minute postsutural supra-alars, 1 postalar and 2 very long cruciate scutellars (with 1 hair on each side); acrostichals indistinct, arranged in 3 pairs almost on one line; 3 long dorsocentrals.

Wing ( Fig. 2 ) normally developed, faintly greyish tinged, with pale brown veins. Costal bristle rather short, brown. Vein Rs nearly as long as crossvein bm-cu. Vein R2+3 very short, meeting costa before wing midway. Vein M turning up and ending near wing tip. No anal vein. Crossvein bm-cu strongly oblique. Crossvein r-m beyond cell bm. Squama minute, brown, with 2 brown cilia. Halter with dusky knob.

Legs almost entirely yellowish-white, only hind femur somewhat darkened at tip. Fore femur ( Fig. 3 ) thickened on basal three quarters; with row of brown posteroventral bristles and 2 long ventral bristles near base. Fore tibia with 1 ventral subapical bristle. Mid femur ( Fig. 4 ) half as stout as fore femur, with 1 strong, brown, anterior preapical bristle. Mid tibia with some weakly sclerotised spiny-bristles in apical half and 1 long posteroventral preapical bristle. Hind femur ( Fig. 5 ) slightly stouter than mid femur, with 1 very long, fine, basal ventral bristle. Hind tibia ( Fig. 5 ) with 5 long black bristles twice as long as tibia is wide (1 anterior, 1 anterodorsal, 3 dorsal) and 1 short ventral apical bristle. Tarsi unmodified.

Abdomen with tergite 1 weakly sclerotised, segment 8 white, otherwise unmodified, covered with short bristles. Terminalia ( Figs 6–9 ) orange yellow. Cerci separated, short, digitiform. Epandrium completely divided. Right epandrial lamella subtriangular, with several long unmodified bristles. Right surstylus not prominent. Left epandrial lamella fused with hypandrium, with several minute bristles apically. Left surstyli consisting of 2 lobes ( Figs 7, 9 ): lower lobe short, elongate oval, with several short, unmodified bristles; upper lobe bearing 4 apical spines and near middle with 1 long bristle sitting on tubercle. Hypandrium ( Figs 6, 7 ) bare. Phallus long, ending in corkscrew-shaped tip. Two rod-shaped apodemes.

Female. Body length 1.3–1.4 mm, wing length 1.1–1.2 mm. Abdominal segment 8 moderately long; cercus yellow, with several brown hairs. Otherwise as in male.

Material examined: Holotype male: PAPUA NEW GUINEA, Madang province, Baiteta, 8-11.V.1995 (rain forest, alt. 150 m, collected in white pan traps (reg. 95026, leg. P. Grootaert).

Paratypes: PAPUA NEW GUINEA: same origin as holotype: 1 male (reg. 95022); 4 males, 4 females (reg. 95023); 7 males, 3 females (reg. 95024); 23 males, 20 females (reg. 95025); 18 males, 12 females (reg. 95026); Baiteta, 25.V.1995, 10 males, 4 females (sweeping, leg. P. Grootaert); 19.V.1995, 8 males, 3 females (M2); 5.VI.1995, 16 males, 8 females (M6); 29.VI.1995, 16 males, 7 females; 29.VI.1995, 8 males, 2 females (A1, white pan traps, leg. O. Missa). THAILAND: 1 male Bok Kai waterfalls (Ranong prov.), 4.IV.1996, (sample n° 96023, leg. P. Grootaert). All preserved in alcohol in the collections of the R.B.I.N.S., Brussels.

Derivatio nominis: The name " flavicaput " alludes to the yellow head.

Distribution. Papua New Guinea, Thailand

Remarks. Similar to the new species described below. The fore coxa of the specimen figured in Fig. 3 bears two fungal like structures on the fore coxa. They probably represent Laboulbeniales.

Figures

FIGURES 1 – 5. Chersodromia flavicaput sp. nov. (Baiteta, Papua New Guinea; paratype male). 1. antenna. 2. wing. 3. fore leg posteriorly. 4. mid leg anteriorly. 5. hind femur and tibia anteriorly. Scale 0.1 mm. lab: Laboulbeniales on fore coxa.

FIGURES 6 – 9. Chersodromia flavicaput sp. nov. (Baiteta, Papua New Guinea; paratype male). 6. hypandrium with appendages. 7. hypopygium ventrally. 8. hypopygium with right epandrial lamella. 9. hypopygium with left cercus and left epandrial lamella. Scale 0.1 mm. lc: left cercus; ls: left surstylus; ph: phallus; rs: right surstylus.