Achalcus cyanocephalus, Pollet, 2005

Pollet, Marc, 2005, Systematic revision of Neotropical Achalcus and a related new genus (Diptera: Dolichopodidae, Achalcinae) with comments on their phylogeny, ecology and zoogeography, Zoological Journal of the Linnean Society 143 (1), pp. 27-73 : 41

ACHALCUS CYANOCEPHALUS SP. NOV. ( FIG. 6 )

Male. Small, rather stout species. Head. Face velvet black with grey patches laterally, narrow, eyes almost touching above clypeus. Frons brilliantly blue. Occiput with strong central concavity, sides bulbous, shining blue. Uppermost 4–5 postocular bristles brownish, lower 7–8 yellowish. Palp moderately large (1/4 of eye), ovoid, brown with paler basis. Antenna largely pale, with scape brown, paler on basal half; pedicel entirely yellow; first flagellomere brownish with less than basoventral half paler, trapezoid, as long as deep and 2¥ as long as scape and pedicel combined. Arista 3.4¥ as long as first three joints of antenna, distinctly apical, entirely brown, pubescent ( Fig. 6B ).

Thorax. Mesonotum with pleura and scutellum reddish yellow with brown areas between and laterad of dc rows; pleura with brownish patches. Postnotum dark reddish yellow with distinct frontolateral black triangle. Metapleura entirely dark brown. Three ac, 2¥ as long as distance between rows. Five dc with 1st dc small. One relatively strong sutural bristle present.

Abdomen with tergites including genital capsule brown. Sternites whitish yellow, with pale (dark yellow) pubescence. Hypopygium. Aedeagus with subapical dorsal bend; ventral bristle of surstylus simple; VEP and DEP present; postgonites not distinct; cercus small, triangular ( Fig. 6C ).

Wing. Halter brown. Wing pale, with R 4+5 and M 1+2 distinctly diverging. Proximal section of vein CuA 1 2.1¥ as long as apical section; CuAx ratio 2.3. Wing length 1.8 mm ( Fig. 6A ).

Legs pale yellow with coxae mainly brown; legs and coxae with brownish bristles. Coxa II brown, coxa III brown with anterior half pale yellow. Trochanter of leg I pale, of leg II and III brown. Femur I without erect ventral bristle and with one preapical av and pv bristles. Femur II with one strong ad, one small av and one strong pv preapical bristles. Femur III with one strong ad, inserted at lower 1/3, and one strong av preapical bristles. Tibia I without dorsal bristles; tibia II with two moderate (2.6–3.2 ¥ tibial depth) ad and one moderate (2 ¥ tibial depth) pd bristles, ad bristles inserted at basal 1/4 and <2/3; tibia III with three moderate ad and three moderate pd bristles; with two true av bristles on basal half and 2/3 amid other erect setae. All tarsi pale yellow with 5th tarsomeres dark. First tarsomere of leg III 0.7¥ as long as 2nd tarsomere.

Female. Unknown.

Etymology. Refers to the brilliantly blue frons in this species (a character shared with A. costaricensis and A. maculipennis ).

Holotype. 1♂, COLOMBIA: 27 mi. S. Popayan Cauca, 1750 m, 5.iii.1955 (Schlinger & Ross) ( CAS; D, hypopygium, antenna and wing mounted).

Figures

Figure 6. Achalcus cyanocephalus sp. nov. (male). A, wing; B, antenna; C, hypopgyium.