Corethrella (Corethrella) contraria Borkent, 2008

Published, First, 2008, The Frog-Biting Midges of the World (Corethrellidae: Diptera), Zootaxa 1804, pp. 1-456 : 118-119

Corethrella (Corethrella) contraria Borkent , new species

DIAGNOSIS: Male adult: only extant species of Corethrella in the New World with a distinct midlength wing band (Fig. 63G), thorax dark brown and the halter as dark as the scutellum (as in Fig. 49C), 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) and with discrete basal and apical pigmentation (as in Fig. 49C), midfemur without scales, abdominal segment 8 lighter than segment 9 and the gonocoxite (Fig. 78J), and aedeagus rounded apically (Fig. 91B). Female adult: only extant species of Corethrella in the New World with palpus as dark as the clypeus ( Fig. 10F), wing broadly pigmented but without the midlength band well defined anteriorly (Fig. 69I), thorax dark brown ( Fig. 49C), midfemur uniformly dark brown, and hind tibia with discrete basal and apical pigmentation.

DESCRIPTION: Male adult. Descriptive statistics: see Tables 2–5. Head: Outline in anterior view laterally elongate (as in Fig. 10F). Two large setae on frons between ventromedial area of ommatida (as in Fig. 16B). Antenna light brown; pedicel with at least one distinctive, more elongate, stout, dorsal or dorsolateral seta; flagellomeres as in Fig. 22D, sensilla coeloconica distributed as in Table 1; flagellomere 13 with welldeveloped apical bifurcation. Palpus dark brown, with segments 4–5 slightly lighter; segment 3 of nearly constant width. Thorax (as in Fig. 49C): Uniformly dark brown, pale sclerites around base of wing, scutellum with darker anteromedial spot. 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. 63G): 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, likely dark scales more basally but specimen worn; veins (other than costa and wing margin) with well-developed scales. Halter as dark as scutellum. Legs (similar to Fig. 49C but see female below): Dark brown, 0.6 midlength of fore-, midtibiae somewhat lighter, hind femur with apical 0.6 paler (not discrete), hind tibia with discrete basal and apical dark brown 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 foreleg fifth tarsomeres undivided, with claws slightly subapical to apical (as in Fig. 75F). Claw of foreleg longer than those of hind leg (midleg claws missing). Each claw without inner tooth. Anterior claws of each leg without a basal prong. Foreleg claws unequal. Midleg claws unknown. Foreleg third tarsomere shorter than fourth tarsomere. Empodia slender. Abdomen (Fig. 78J): Light brown, with tergite 1, sternites 1–2 medium brown, posterior portion of tergites 6, 7 darker, segment 8 light brown, segment 9 medium brown. Genitalia (Fig. 91B): Gonocoxite medium brown, slightly lighter apically, 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, 1–4 thicker than 5, 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 (in retracted position) mostly straight, bent subapically, slender, of more or less equal thickness for entire length, somewhat expanded apically, apex rounded; one elongate, slender subbasal seta, situated anteriorly or anteroventrally; apical seta slender, elongate, simple. Aedeagus slender, elongate, narrow, tapering gradually to apex, rounded apically, with lateral margins not fused.

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 brown; with flagellomeres as in Fig. 29E, sensilla coeloconica distributed as in Table 1. Clypeus ( Fig. 18D) squarish. Mandible with moderately sized, pointed teeth. Palpus as in Fig. 34P. Wing (Fig. 69I): nearly entirely with dark scales, light patch over and just basal to r-m. Legs ( Fig. 49C): Pigmentation as for male but tibia with darker pigmentation apically, midtibia uniformly medium brown, hind femur with lighter apical portion poorly defined, in one specimen hind femur uniformly medium brown. Claws of each leg equal to those of others; equal on each leg, simple (without inner teeth). Abdomen: Medium brown. Cercus dark brown.

Immatures. Unknown.

DISTRIBUTION AND BIONOMICS: Corethrella contraria is known from two localities near San Carlos , Costa Rica (Fig. 119A) at an altitude of 50–100 m. Specimens were collected using Malaise and interception traps .

TAXONOMIC DISCUSSION: The single male and females were associated through the shared presence of a shared pigmentation pattern and were collected together at one locality. One female paratype (collected 23-VI–23-VII-2004) had more poorly defined leg pigmentation and overall appeared lighter. It may represent a somewhat teneral specimen or perhaps another unnamed species, emerging earlier than the others in the type series. Overall the variation in pigmentation of the female hind femur was greater than present in other species of Corethrella , also indicating the possibility of further taxa under this name.

TYPES: Holotype, male adult on microscope slide, labeled " HOLOTYPE Corethrella contraria Borkent ”, “ COSTA RICA. Prov. Alajuela, San Carlos, Boca Tapada , Laguna Lagarto Lodge , 50– 100 m. 23 JUL-17 SEP 2004. Tp. Malaise. B. Hernandez, LN 296095 516714 #78134” ( INBC) . Allotype, female adult on microscope slide, labeled as for holotype ( INBC) . Paratypes: 2 ♀ from type locality ( CNCI, INBC) ; 2 ♀ from type locality but 23-VI–23-VII-2004 ( CNCI; INBC) ; 2 ♀, Finca de Sergio Murillo, Boca Tapada, Pital, San Carlos, Costa Rica , 50–100 m, 23–24-VII-2004 ( INBC) .

DERIVATION OF SPECIFIC EPITHET: The name contraria (contrast) is proposed to reflect the discrete hind tibial pigmentation of adults of this species (also present in some others).