Achalcus costaricensis, 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 : 39-41

ACHALCUS COSTARICENSIS SP. NOV. ( FIG. 5 )

Male. Small, rather slender species. Head. Face dark brown, dusted, as wide as ocellus with eyes almost touching above clypeus. Frons dark brown with strong blue reflection. Occiput flat, dark brown, shining. All postocular bristles dark. Palp large (2/5 of eye), ovoid, brown with basal 1/3 yellowish; with brown pubescence, and one strong brown apical bristle ( Fig. 5E ). Proboscis well developed, 0.6¥ as long as head. Antenna mainly brown with pedicel brownish yellow, infuscated dorsally; first flagellomere brown with basoventral half yellow, rounded triangular, 1.2¥ as long as deep and 1.2¥ as long as scape and pedicel combined. Arista 2.4¥ as long as first three joints of antenna, inserted apically on outer face; with 1st segment dark and 2nd white except for extreme basis; with short pubescence ( Fig. 5C ).

Thorax. Mesonotum and scutellum dark brown, shining bluish. Upper pleura dark brown, lower reddish yellow. Postnotum entirely dark brown with broad black frontolateral edge. Lower half of metapleura pale brown, upper half pale yellow. Three ac, more than 1.5¥ as long as distance between rows. One large sutural bristle present.

Abdomen with small bare 6th segment. Abdominal tergites including genital capsule dark brown, 2nd tergite and sternites slightly paler. Aedeagus with distinct subapical dorsal bend; ventral bristle of surstylus simple; VEP and DEP evident; postgonites pale but evident; cercus small, triangular ( Fig. 5F ).

Wing. Halter pale, squamal fringe brown. Wing pale, with R 4+5 and M 1+2 diverging. Proximal section of vein CuA 1 2.3¥ as long as apical section; CuAx ratio 2.2. Wing length 1.9–2.1 mm (n = 10) ( Fig. 5A ).

Legs yellow with coxae and trochanters pale yellow. Femur I without erect ventral bristle; with one av and one strong pv preapical bristles ( Fig. 5B ). Femur II with one strong ad, one strong av and one strong pv preapical bristles. Femur III with one strong ad and one strong av preapical bristles. Tibia I without dorsal bristles; tibia II with two moderate (1/7 of tibial length) ad and one smaller pd bristles, ad bristles inserted at about basal 1/3 and 2/5; tibia III with 2–3 rather small ad and three rather small pd bristles; with one true ventral bristle at apical 2/5. All tarsi entirely yellow. First tarsomere of leg III 0.9¥ as long as 2nd tarsomere. Body length 1.8–2.1 mm (n = 10).

Female. As in male, except for the following: face about as wide as ocellus. Palp rounded rectangular, with strong pubescence. Antenna entirely dark brown with 1st segment of arista brownish and 2nd white ( Fig. 5D ). Abdomen with six pubescent segments; 8th reddish brown with eight stout dark dornen; cercus reddish yellow, short. Body length 2.0– 2.3 mm, wing length 1.9–2.2 mm (n = 10).

Etymology. Refers to the country where the species was initially discovered. Thus far it has only been recorded from Costa Rica, where it has been found in sometimes large numbers at higher altitudes.

Holotype. 1♂, COSTA RICA: San José, 26 km N. of San Isidro , 2100 m, 9∞30¢N, 83∞43¢W, ix- x.1992, MT (Hanson) ( INBio; W).

Allotype. 1♀, same data.

Other paratypes. COSTA RICA: 1♀, San José, 2 km W. of Empalme , 2300 m, 9∞43¢N, 83∞58¢W, vi.1995 ; 2♀, vii.1995; 41♂, 73♀, 26 km N. of San Isidro , 2100 m ,

F

9∞30¢N, 83∞43¢W, ix- x.1992 (wing, antenna, leg I and hypopygium of 2♂; antenna of 1♀ mounted); 7♀, Zurqui de Moravia , 1600 m, 10∞03¢N, 84∞01¢W, ii.1995, all collected by MT (Hanson) ( INBio; W) .

Figures

Figure 5. Achalcus costaricensis sp. nov. (male, unless mentioned otherwise). A, wing; B, coxa and femur I; C, antenna; D, female antenna; E, palp; F, hypopygium.