Corethrella (Corethrella) brevivena Borkent, 2008

Published, First, 2008, The Frog-Biting Midges of the World (Corethrellidae: Diptera), Zootaxa 1804, pp. 1-456 : 66-67

Corethrella (Corethrella) brevivena Borkent , new species

DIAGNOSIS: Male and female adults: only extant species of Corethrella with an extremely short R 2, terminating about 0.6 of the distance between the apex of R 1 and R 3 (Figs. 61K, 67F); also the only species in which the anal vein does not reach the wing margin (Figs. 61K, 67F).

DESCRIPTION: Male adult. Descriptive statistics: see Tables 2–5. Head: Outline in anterior view nearly circular (as in Fig. 7D). Two large setae on frons between ventromedial area of ommatida (as in Fig. 16C). Antenna uniformly brown; pedicel without distinctive, more elongate, stout, dorsal or dorsolateral setae; flagellomeres as in Fig. 19J, sensilla coeloconica distributed as in Table 1; flagellomere 13 with welldeveloped apical bifurcation. Palpus brown; segment 3 swollen apically. Thorax (as in Fig. 41C): nearly uniformly brown, with pale spot on posterior border of katepisternum, pale sclerites around base of wing. Posterior portion of dorsocentral row with 2 elongate setae situated somewhat lateral to one another. Prescutal suture short, not extending more than half way to dorsocentral row of setae. Anterior anepisternum divided diagonally by sinuous suture, dorsal portion about equal to ventral portion. Ventral portion of posterior anepisternum not differentiated from dorsal portion, anterior margin more darkly pigmented than posterior margin. Wing (Fig. 61K): Apex of R 2 basal to apex of M 1. Plain, without pattern of pigmented veins and/or scales; veins (other than costa and wing margin) with only setae. Halter as slightly lighter than scutellum. Legs (as in Fig. 41C): Uniformly pigmented. With only slender setae, lacking scales (except for some in patch of whip-like setae on posterior portion of hind tibia). Midleg with thick, subapical setae on each of at least tarsomeres 1–3. Apices of fore–, midleg fifth tarsomeres undivided, with claws slightly subapical to apical (as in Fig. 75F). Claw of foreleg longer than those of mid–, hind leg. Each claw without inner tooth. Anterior claws of each leg without a basal prong. Foreleg claws unequal. Midleg claws equal. Foreleg third tarsomere longer than fourth tarsomere. Empodia slender. Abdomen (Fig. 76K): Uniformly brown. Genitalia (Fig. 85C): Gonocoxite uniformly medium brown, gently tapering; anteromedial area with spicules similar in length to those elsewhere on gonocoxite; with poorly-defined dorsal row of setae, with most setae of similar thickness as some other setae on gonocoxite, most posterior seta of row largest, with row curving posteromedially with posteriormost seta of row positioned dorsomedially. With one dorsomedial stout seta, tapering from base. Gonostylus (in retracted position) nearly straight, somewhat thick, base thicker than remainder, rounded apically; one elongate, thick subbasal seta, situated posteroventrally or posteriorly; with well-developed apical peg. Aedeagus slender, elongate, tapering from base but with abrupt narrowing subapically, pointed apically, with lateral margins fused at apex.

Female adult. Descriptive statistics: see Tables 6–11. As for male, with following differences. Head: Coronal suture absent (as in Fig. 16C). Antennal flagellomeres as in Fig. 26K, sensilla coeloconica distributed as in Table 1. Clypeus ( Fig. 17O) squarish. Mandible with small, pointed teeth. Palpus as in Fig. 33Q. Wing (Fig. 67F). Legs: Claws of each leg equal to those of others; equal on each leg, simple (without inner teeth). Abdomen: Uniformly brown.

Immatures. Unknown.

DISTRIBUTION AND BIONOMICS: Corethrella brevivena is known only from the property of Cabinas Chimuri, near Puerto Viejo on the east coast of Costa Rica (Fig. 119A) at an altitude of about 50 m. Specimens were collected by sweeping along a stream and small waterfall.

TAXONOMIC DISCUSSION: Males and females were associated through the shared presence of a unique wing venation and were collected at the same place and date.

TYPES: Holotype, male adult on microscope slide, labeled " HOLOTYPE Corethrella brevivena Borkent , 1 km W. Puerto Viejo, Limón, Costa Rica, 30-X-1993, A. Borkent CD1644" ( CNCI) . Allotype, female adult on microscope slide, labeled as for holotype ( CNCI) . Paratypes: 1 ♂, 1 ♀ from type locality ( USNM) .

DERIVATION OF SPECIFIC EPITHET: The name brevivena (short, vein) refers to the uniquely shortened terminal veins of the wing.