Corethrella (Corethrella) remiantennalis Borkent, 2008

Published, First, 2008, The Frog-Biting Midges of the World (Corethrellidae: Diptera), Zootaxa 1804, pp. 1-456 : 63-64

Corethrella (Corethrella) remiantennalis Borkent , new species

DIAGNOSIS: Male adult: only extant species of Corethrella with an elongate, flattened bristle on flagellomere 10 ( Fig. 20A). Female adult: unknown.

DESCRIPTION: Male adult. Descriptive statistics: see Tables 2–5. Head: Outline in anterior view nearly circular (as in Fig. 7C). 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. 20A, sensilla coeloconica distributed as in Table 1; flagellomere 13 with welldeveloped apical bifurcation; flagellomere 10 with very elongate stout seta, flattened at apex, narrowing to sharp tip ( Fig. 20A). Clypeus squarish. Palpus (as in Fig. 33O) brown; segment 3 swollen apically. Thorax ( Fig. 41A): nearly uniformly brown, posterior portion of posterior anepisternum pale, 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. 61I): Apex of R 2 equal to apex of M 1. Plain, without pattern of pigmented veins and/or scales; veins (other than wing margin) with very slender scales. Halter nearly as dark as scutellum. Legs ( Fig. 41A): Uniformly medium brown, with midfemur either uniformly pigmented or with very base paler; basal 0.3 of hind femur somewhat lighter. 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. 76I): Tergites, sternites nearly uniformly pigmented brown, with very narrow band of dark brown on posterior margin segment 7. Genitalia (Fig. 85A): Gonocoxite uniformly medium brown, gently tapering; anteromedial area with spicules similar in length to those elsewhere on gonocoxite; with well-defined dorsal row of setae, basal seta of row thinnest, 3 rd and 4 th largest (from 2 km NE Tárcoles) or with all uniformly slender (from Barbilla National Park), with row curving posteromedially with posteriormost seta of row positioned dorsomedially. With one dorsomedial stout seta, more or less of even thickness for most of length, tapering near apex. Gonostylus (in retracted position) slightly curved, thicker basally, slender for apical half, rounded apically; one elongate, thick subbasal seta, situated ventrally; with well-developed apical peg. Aedeagus slender, elongate, tapering gradually to apex, pointed apically, with lateral margins separate apically.

Female adult and immatures. Unknown.

DISTRIBUTION AND BIONOMICS: Corethrella remiantennalis is known from two localities in Costa Rica, one on west coast and the other on the east coast (Fig. 120B) at altitudes of 100–300 m. The holotype was collected by sweeping near the tank providing water to the administration building at Carara National Park and the paratype was taken with a yellow pan trap .

TAXONOMIC DISCUSSION: The distinctive and highly modified seta on the male flagellomere 10 ( Fig. 20A) is unique in the Culicomorpha . The male of C. blandafemur also has a modified seta on its antenna but it is on flagellomere 6 ( Fig. 20B).

The two males representing this species differed in some details of pigmentation (base of midfemur), pattern of sensilla coeloconica on the antenna, and degree of development of setae in the dorsal row and position of the dorsomedial seta on the gonocoxite. It is quite possible that they represent two species.

The male from Barbilla National Park was collected with six females ( INBC), none of, or any of which, could include the female of this species. However, it was clear that there were at least two species represented by these females (not described here) and none matched the male exactly in size and details of thoracic pigmentation .

TYPES: Holotype, male adult on microscope slide, labeled " HOLOTYPE Corethrella remiantennalis Borkent , 2 km NE Tárcoles, Costa Rica, 1-I-1994, A. Borkent CD1727" ( CNCI). 1 ♂ paratype, 2 km S. de Estación por la Quebrada, Barbilla National Park, Turrialba , Cartago, Costa Rica, 300 m, 15-18-I-2001 ( INBC).

DERIVATION OF SPECIFIC EPITHET: The name remiantennalis (oar, antenna) refers to the peculiar, highly modified seta arising from the 10 th antennal flagellomere of the male of this species.