Eumeka koghii, McAlpine, 2007

McAlpine, D. K., 2007, New Taxa of Signal Flies (Diptera: Platystomatidae) of New Caledonia, Records of the Australian Museum 59 (1), pp. 65-77 : 70-71

Eumeka koghii n.sp.

Fig. 5

Type. HOLOTYPE! (unique), New Caledonia: Mount Koghi [or Montagnes des Koghis], 600 m, 26–30.i.1963, C.Y., N.L.K., light trap ( BPB).

Description. Female (male unknown). Resembling E. hendeli McAlpine (see McAlpine, 2001) but smaller.

Coloration. Head with ground-colour largely brown; cheek and lower occiput brownish-tawny; fronto-orbital margin, parafacial, and postgenal region densely silvery-pruinescent; antennal groove more finely and thinly silvery-pruinescent. Palpus brown to tawny-brown. Mesoscutum with blackish ground-colour, becoming brown towards lateral margins, with median silver-grey pruinescent stripe joined to transverse prescutellar pruinescent zone, and with broader lateral pruinescent zone both before and behind transverse suture; humeral callus whitish-pruinescent only towards posterior margin, otherwise shining brown with pale yellowish hairs; scutellum shining blackish, with anterodorsal zone of thin greyish pruinescence; pleura brown and shining in part; mesopleuron with silvery-pruinescent posterior marginal band narrowed dorsally, ventrally extending broadly across sternopleuron; pleurotergite with silvery-white pubescence-pruinescence. Coxae brown to tawny; fore coxa densely silvery-pruinescent on anterior surface; femora yellow; tibiae and tarsi dark brown to tawnybrown. Wing ( Fig. 5 ) differing from other Eumeka spp. in broader brown costal band between veins 1 and 4 and large brown mark enclosing both anterior and discal crossveins; axillary lobe and squama white. Halter with tawny-yellow base and brown capitellum. Abdomen dark brown to tawny brown, largely shining with whitish hairs on tergites 1 and 2, mostly blackish hairs on other tergites; tergite 2 with rather small median whitish-pruinescent zone on posterior margin; tergite 3 with whitish-pruinescent zone on anterior margin which does not extend to lateral margin; tergite 4 with whitish-pruinescent zone on anterior margin, which broadens laterally and extends broadly over whole lateral margin; tergite 5 broadly whitish-pruinescent on lateral margin only; sternite 1 brown, shining, whitish-pruinescent on lateral margin and more narrowly so on posterior margin; sternites 2 and 3 almost entirely whitish-pruinescent; ovipositor sheath dark brown; aculeus yellow.

Head of similar shape and proportions to that of E. hendeli ; facial carina almost flat-topped, depressed near mid-length so that central part is not visible in profile; height of cheek 0.28 of height of eye; fronto-orbital bristles two, reclinate, but posterior one strongly curved outwards; postgenal bristle large; setulae present on parafacial, but those near and just above its mid-height smaller and inconspicuous. Antenna (without arista) slightly shorter than face; arista almost twice as long as rest of antenna; segment 6 with sparse very minute pubescence near base only. Prelabrum moderately developed; its anterior surface almost vertical.

Thorax. Setulae on mesopleuron (perhaps sexually dimorphic) shorter than in either sex of E. hendeli , those near posterior margin moderately short, black, moderately thick, those on upper part fine, minute, and pale, those in compact ventral group black, thick and somewhat spinescent; setulae on anterior part of pteropleuron short, rather thick, black; thoracic chaetotaxy as for genus. Legs as for genus; bristles on hind femur rather weak, especially the pale anterior ones on basal half. Wing: vein 1 without ventral setulae; distal section of vein 4 slightly arched, apically slightly diverging from vein 3; cell-4 index = 0.76; first basal cell more extensively microtrichose than in other Eumeka species, particularly on distal half; alula entirely microtrichose; squama rather narrowly rounded, not at all produced posteriorly (in contrast to E. hendeli ).

Abdomen rather broad anteriorly, with no tendency towards petiolation; tergite 5 distinctly shorter than tergite 4; aculeus very slender; spiracle 5 apparently situated in pleural membrane below mid-length of tergite 5.

Dimensions. Total length 5.4 mm (abdomen flexed); length of thorax 2.7 mm; length of wing 6.1 mm.

Distribution New Caledonia: mountains in south of Grande Terre.

Notes

From comparison of certain species in the platystomatine genera Rhytidortalis Hendel , Euprosopia Macquart , and Pseudocleitamia Malloch the armature of the mesopleuron seems likely to be sexually dimorphic (see McAlpine, 2000 for Rhytidortalis ; 1973 for Euprosopia ; 2001 for Pseudocleitamia ).

Figures

Figs 5, 6. Wings of signal flies. (5) Eumeka koghii. (6) Pogonortalis monteithi.