Corethrella (Corethrella) curta Borkent, 2008

Published, First, 2008, The Frog-Biting Midges of the World (Corethrellidae: Diptera), Zootaxa 1804, pp. 1-456 : 163-164

Corethrella (Corethrella) curta Borkent , new species

DIAGNOSIS: Male adult: only extant species of Corethrella in the New World with flagellomeres 4–10 each with few sensilla trichodea (Fig. 65L), flagellomeres 9–12 each with one sensillum coeloconicum, a distinct midlength wing band (Fig. 64L), thorax dark brown (as in Fig. 55B), halter and scutellum equally dark brown, midfemur dark brown and equal to that of base of hind femur, base of hind tibia darkly pigmented (contrasting with pale apex of hind femur), with apical 0.2–0.3 of hind tibia pale (as in Fig. 55B), midfemur without scales, abdominal segments 7–9 and base of gonocoxite similar in pigmentation (Fig. 80E). Female adult: only extant species of Corethrella in the New World with flagellomeres 2 and 3 very short ( Fig. 31D), a distinct midlength wing band (Fig. 71D), thorax dark brown ( Fig. 55B), halter and scutellum equally dark brown, midfemur dark brown and equal to that of base of hind femur, base of hind tibia darkly pigmented (contrasting with pale apex of hind femur) ( Fig. 55B), and midfemur without scales.

DESCRIPTION: Male adult. Descriptive statistics: see Tables 2–5. Head: Outline in anterior view laterally elongate (as in Fig. 13B). Two large setae on frons between ventromedial area of ommatida (as in Fig. 16B). Antenna medium brown; pedicel with at least one distinctive, more elongate, stout, dorsal or dorsolateral seta; flagellomeres as in Fig. 24A, sensilla coeloconica distributed as in Table 1; flagellomere 13 with well-developed apical bifurcation. Palpus medium brown; segment 3 somewhat ovoid, swollen at or near midlength. Thorax (as in Fig. 55B): Medium brown, pale sclerites around base of wing. Posterior portion of dorsocentral row with group of about 3 elongate setae. 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 triangular, uniformly brown, with anterodorsal margin thick. Wing (Fig. 64L): Apex of R 2 basal to apex of M 1. Anterior margin with differently, discretely pigmented scales (indicating anterior margin of midlength band), with midlength band, more basal dark scales on C, Sc, R, M, subapical dark scales on R 2, R 3, in some a few on R 4+5; veins (other than costa and wing margin) with well-developed scales. Halter as dark as scutellum. Legs (as in Fig. 55B): Dark brown, with apical 0.2–0.3 hind femur pale, hind tibia with non-discrete apical slightly darker pigmentation. 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 shorter than fourth tarsomere. Empodia slender. Abdomen (Fig. 80E): Medium to dark brown, with posterior margins of each of tergites 5–7 slightly darker in some. Genitalia (Fig. 96A): Gonocoxite medium to dark brown, strongly tapering; anteromedial area with spicules similar in length to those elsewhere on gonocoxite; with well-defined dorsal row of setae, with seta 2 slightly thicker than others, with row restricted to dorsal portion of gonocoxite. With one dorsomedial stout seta, more or less of even thickness for most of length, tapering near apex. Gonostylus (partially extended) straight or gently curved, more curved apically, slender, expanded apically, of more or less equal thickness for entire length, pointed apically; one elongate, slender subbasal seta, situated anteriorly or anteroventrally; apical seta slender, elongate, simple. Aedeagus slender, elongate, tapering gradually to apex, 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 elongate, extending ventrally past ommatida (as in Fig. 16B). Antenna medium to dark brown; with flagellomeres as in Fig. 31D, sensilla coeloconica distributed as in Table 1. Clypeus ( Fig. 18 AA) squarish. Mandible with small, pointed teeth. Palpus as in Fig. 35G. Wing (Fig. 71D). Legs: Claws of each leg equal to those of others; equal on each leg, simple (without inner teeth). Abdomen: Medium to dark brown with segments 8–9 darker brown in those with anterior portion of abdomen medium brown. Cercus dark brown.

Immatures. Unknown.

DISTRIBUTION AND BIONOMICS: Corethrella curta is known only from Costa Rica (Fig. 121B) at altitudes ranging from 500–1850 m (possibly as low as 400 m). Specimens have been collected using light, Malaise and frog-call traps. The serrate mandibles of the female adults and their attraction to Hyla gratiosa calls suggest that they feed on frog blood in nature.

TAXONOMIC DISCUSSION: Males and females were associated through the shared presence of a common pigmentation pattern and reduced antennal flagellomeres 1–3. They were collected together at Tapantí National Park, Costa Rica. Males look very similar to those of C. ranapungens but are distinguished by the presence of far fewer setae on flagellomeres 4–10. Some C. ranapungens males have short flagellomeres 1– 3, similar to those of C. curta .

TYPES: Holotype, male adult on microscope slide, labeled " HOLOTYPE Corethrella curta Borkent ”, “ 8 km SE Orosi, Tapantí National Park, CR, 11-XII-1999, A. Picado y A. Borkent, 193200N/560200E, 1200 m, CD5032” (CNCI). Allotype, female adult on microscope slide, labeled as for holotype ( CNCI) . Paratypes: 2 ♀, Estación Cabro Muco , Macizo Miravalles, Guanacaste, Costa Rica, 1100 m, 24–25-IX-2003 ( INBC) ; 1 ♀, from previous locality but 28-IX–5-X-2003 ( INBC) ; 1♀, Volcán Tenorio, Guanacaste, Costa Rica, 1650 m, 5– VIII-5-X-2003 ( INBC) ; 2 ♀, Eladio’s, Reserva Monteverde, Costa Rica, 830 m, 26–28-X-2005 ( INBC) ; 1 ♂, 11 ♀, from type locality (1 ♂, 6 ♀, CNCI; 5 ♀, INBC) ; 1 ♀, from type locality but 12-XII-1999, 1600 m ( INBC) ; 2 ♀, between Porras and Villegas Rivers , Costado Torre del I.C.E., Sector La Represa, Costa Rica, 1800 m, XI-1996 ( INBC) ; 1 ♀ as for previous locality but IV-1997 ( USNM) ; 1 ♂, Estación Quebrada González, Braulio Carrillo National Park , Costa Rica, 400–500 m, 24-IX-2002 ( INBC) ; 1 ♀, Est. Santa Elena, Chirripó NP, San Jose, Costa Rica, 1850 m, 20-III–15-IV-1997 ( INBC) .

DERIVATION OF SPECIFIC EPITHET: The name curta (short) refers to the short flagellomeres 1–3 of the adults of this species.