Corethrella (Corethrella) carariensis Borkent, 2008

Published, First, 2008, The Frog-Biting Midges of the World (Corethrellidae: Diptera), Zootaxa 1804, pp. 1-456 : 68-69

Corethrella (Corethrella) carariensis Borkent , new species

DIAGNOSIS: Male adult: only extant species of Corethrella with a gonocoxite with 3 stout dorsomedial setae originating from a sclerotized plate and with the setae of the dorsal row all slender and not bent subapically (Fig. 85D). Female adult: only extant species of Corethrella in the New World with a plain wing (Fig. 67H), a medium to dark brown katepisternum with the dorsal margin pale ( Fig. 42A), with nearly uniformly medium brown legs (with only the base of the midfemur slightly more pale in some specimens) and about the basal half of the hind femur pale and with the fore trochanter pale, contrasting with the dark base of the forefemur ( Fig. 42A), all femora lacking scales.

DESCRIPTION: Male adult. Descriptive statistics: see Tables 2–5. Head: Outline in anterior view laterally elongate (as in Fig. 7E). Four large setae on frons between ventromedial area of ommatida (as in Fig. 16D) Antenna uniformly brown; pedicel without distinctive, more elongate, stout, dorsal or dorsolateral setae; flagellomeres as in Fig. 19K, sensilla coeloconica distributed as in Table 1; flagellomere 13 with well-developed apical bifurcation. Palpus brown; segment 3 slightly ovoid. Thorax (as in Fig. 42A): Scutum light brown with darker lateral patch, pleuron mostly pale with postpronotum light brown to nearly completely darkly pigmented, with ventral portion of katepisternum, dorsal portion of anterior anepisternum, all of posterior anepisternum more darkly pigmented, anepimeron with to dark brown pigmentation. 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 triangular, uniformly brown, with anterodorsal margin thick. Wing (Fig. 61L): Apex of R 2 equal to apex of M 1. Plain, without pattern of pigmented veins and/or scales; veins (other than costa and wing margin) with welldeveloped scales. Halter dark brown, equal to scutellum. Legs (as in Fig. 42A): Nearly uniformly medium brown legs with base of midfemur slightly more pale, about basal half of hind femur pale. 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. Apex of foreleg fifth tarsomeres undivided, with claws apical. Apex of midleg fifth tarsomeres bilobed in dorsoventral view, with claws subapical. Elongate claw of foreleg shorter than that of midleg, both longer than those of hind leg. Each claw without inner tooth. Anterior claws of each leg without a basal prong. Foreleg claws unequal. Midleg claws unequal. Foreleg third tarsomere longer than fourth tarsomere. Empodia slender. Abdomen (Fig. 76L): Segments 1–7 medium brown, segment 8 pale, lateral portions of tergite 9 medium brown (pale medially). Genitalia (Fig. 85D): Gonocoxite uniformly pale or light brown, tapering; anteromedial area with spicules similar in length to those elsewhere on gonocoxite; with well-defined dorsal row of setae, all slender, with row restricted to dorsal portion of gonocoxite. With three dorsomedial stout setae, tapering from base, similar in size and length, bases joined by sclerotized plate. Gonostylus (in retracted position) slightly curved subapically, thicker for basal third and apical 1/4, rounded apically; one elongate, thick subbasal setae, situated posteroventrally; apical seta moderately thick, elongate, simple. Aedeagus slender, tapering gradually to apex, pointed apically, with lateral margins fused at very 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. 16D). Antenna brown; with flagellomeres as in Fig. 27A, sensilla coeloconica distributed as in Table 1. Clypeus ( Fig. 17Q) squarish. Mandible with large, triangular teeth. Palpus as in Fig. 33S. Wing (Fig. 67H). Legs: Claws of each leg equal to those of others; equal on each leg, simple (without inner teeth). Abdomen: Segments uniformly medium brown.

Immatures. Unknown.

DISTRIBUTION AND BIONOMICS: Corethrella carariensis is known from the western and eastern lowlands of Costa Rica (Fig. 119B) at altitudes ranging from 0– 100 m. Specimens have been collected with a Malaise trap (male) and a frog-call trap. 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 are tentatively associated. They share a similar pigmentation pattern and are the only members of the peruviana species group, other than C. manaosensis (from Brazil), in which the legs do not have well-developed scales. The adult thoracic pigmentation of the females is strikingly variable, ranging from most pleural sclerites quite pale to dark brown, with the specimens from western Costa Rica being lighter than those from the east coast (Hitoy Cerere). Degree of pigmentation is generally only slightly variable in other species of Corethrella , suggesting the presence of more than one species here. However, I could find no other differences and the specimens from Hitoy Cerere showed significant variation within one sample (with the anepimeron light to dark brown).

TYPES: Holotype, male adult on microscope slide, labeled " HOLOTYPE Corethrella carariensis Borkent ”, “ Costa Rica, Prov. Guanacaste, R. Priv. Nosara, Desemboc, Rio Nosara, 0– 5 m. 13–17-VI-2004. B. Gamboa, D. Briceno, M. Moraga, Y. Cardenas, Malaise, L.N. 217060 352800, #77439" (INBC). Allotype, female adult on microscope slide, 5 km NE Tárcoles , Costa Rica, 20-VII-1993, A. Borkent ( CNCI) . Paratypes: 3 ♀, from allotype locality (1, INBC; 2, CNCI) ; 1 ♀ from type locality but 2-IX-1993 ( CNCI) ; 1 ♀, Manuel Antonio National Park , Costa Rica, 17-XI-1993 ( CNCI) ; 1 ♀, Punta Marenco , 8°41'06"N 83°42'32"W, Puntarenas, Costa Rica, 4-III-2001, J.V. Dahlem ( INBC) ; 8 ♀, Hitoy Cerere Biological Reserve , nr. administration building (9°40.30'N, 83°01.20'W), Costa Rica, 100 m, 11-X-2003 (6, CNCI; 1, INBC; 1 USNM) .

DERIVATION OF SPECIFIC EPITHET: The name carariensis refers to the collecting site of the allotype in Carara National Park, where the author spent many wonderful hours collecting Corethrella and other Diptera in 1993–94.