Corethrella (Corethrella) douglasi Borkent, 2008

Published, First, 2008, The Frog-Biting Midges of the World (Corethrellidae: Diptera), Zootaxa 1804, pp. 1-456 : 109-111

Corethrella (Corethrella) douglasi Borkent , new species

DIAGNOSIS: Male and female adults: only extant species of Corethrella in the New World with the wing with a distinct midlength band (Figs. 63D, 69C), with the katepisternum darker dorsally than ventrally ( Fig. 48A), with a uniformly light brown midfemur (some with very faint apical darker pigmentation) contrasting with the dark base of the hind femur, and with the hind tibia with discrete basal and apical bands ( Fig. 48A).

DESCRIPTION: Male adult. Descriptive statistics: see Tables 2–5. Head: Outline in anterior view laterally elongate (as in Fig. 9I). Two large setae on frons between ventromedial area of ommatida (as in Fig. 16E). Antenna light brown; pedicel with at least one distinctive, more elongate, stout, dorsal or dorsolateral seta; flagellomeres as in Fig. 22A, sensilla coeloconica distributed as in Table 1; flagellomere 13 with welldeveloped apical bifurcation. Palpus pale; segment 3 of constant width or slightly oval. Thorax (as in Fig. 48A): Light brown with darker pigmentation in band from pronotum to anterior portion of anepimeron and dorsal portion of katepisternum. Posterior portion of dorsocentral row with group of about 11 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. 63D): 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; veins (other than costa and wing margin) with well-developed scales. Halter very light brown, lighter than scutellum. Legs (as in Fig. 48A): Light brown with mid-coxa, trochanter somewhat darker, apex of midfemur slightly pigmented in some; hind-coxa, trochanter, very base of hind femur dark brown; hind tibia with base, apex discrete dark brown, at least mid-, hind leg tarsomeres 2– 4 with banding. 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. 78G): Tergites 1–7 uniformly pigmented light brown, with slight pigmentation on posterior margin of tergites 6, 7 in some. Sternites 1–2 medium brown, 3–7 light brown with posterior margins medium brown. Segments 8 medium brown. Segment 9 medium brown in some. Genitalia (Fig. 90C): Gonocoxite light brown, strongly tapering; anteromedial area with spicules similar in length to those elsewhere on gonocoxite; with well-defined dorsal row of setae, with setae 1, 2 thicker than others, 2 thicker than 1, 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 (partially extended) basally straight, evenly curved for apical 1/3; slender, somewhat thicker for basal 1/ 3, of more or less equal thickness for remainder, tapered apically; one elongate, slender subbasal seta, situated anteriorly or anteroventrally; apical seta slender, short, simple. Aedeagus slender, elongate, tapering gradually to apex, pointed apically, with lateral margins fused subapically.

Female adult. Descriptive statistics: see Tables 6–11. As for male, with following differences. Head: Coronal suture short, not extending ventrally between ommatidia (as in Fig. 16E). Antenna flagellomeres 1–6 light brown, 7–13 somewhat darker; with flagellomeres as in Fig. 28K, sensilla coeloconica distributed as in Table 1. Clypeus ( Fig. 17 AN) squarish. Mandible with large, apically somewhat squared teeth. Palpus as in Fig. 34J. Wing (Fig. 69C). Legs: Claws of each leg equal to those of others; equal on each leg, simple (without inner teeth). Abdomen: Light brown, with sternites 1, 2, segment 8 medium brown. Cercus light brown.

Pupa. Mostly undescribed. Thorax: Scutum, metathorax each with spherical sensory pit (as in Fig. 100A). Respiratory organ (Fig. 102C): Tubular. Abdomen (Fig. 106D): Segments 3–7 not expanded laterally. Paddle only moderately elongate; apicodorsal thick spine articulating; apicoventral seta longer than thick spine.

Larva. Undescribed.

Egg. Unknown.

DISTRIBUTION AND BIONOMICS: Corethrella douglasi is known from Costa Rica (Fig. 120A) at altitudes ranging from 80–1090 m, with most records from over 500 meters. Specimens have been collected using a sweep net, Malaise traps and by rearing. Reared specimens were collected as larvae or pupae from the leaf axils of Dieffenbachia longispatha in Volcán Tenorio National Park and from a bromeliad, Pitcairnia valeni , in Reserva Biológica Alberto Ml. Brenes.

Three females were collected with an ABC/CO 2 /light trap at 5 km W. Rincón and one female with an ABC/light/octenol trap at Los Planes Station in Corcovado National Park. It is uncertain what these latter specimens were attracted to. Generally Corethrella are rare in light traps and a frog-call trap was run nearby the ABC trap at 5 km W. Rincón without collecting C. douglasi , suggesting that it is not attracted to the call of H. gratiosa . The female adults have serrate teeth indicating that they do indeed bite.

TAXONOMIC DISCUSSION: Males and females were associated through the shared presence of a distinctive pigmentation pattern and were reared together from a single collection of immatures. It is a striking feature of the distribution of this species that there appear to be two populations: one at upper elevations above 500 meters in most of Costa Rica and one in the Osa Peninsula in southwestern Costa Rica. This suggests the possibility of two species but I was unable to distinguish these on morphological grounds. Alternately, the lowland records in the Osa Peninsula may be specimens descending from higher elevations in the peninsula.

TYPES: Holotype, male adult with pupal exuviae on microscope slide, labeled " HOLOTYPE Corethrella douglasi Borkent , Costa Rica”, “ COSTA RICA, Prov. Alajuela, Upala, Bijaqua, ACA-T, P.N. Volcán Tenorio, Sendero al Volcán Tenorio, orilla del rio Roble, 850 m, 27 JUN 2004, G. Chaverri. En pecidos de Dieffenbachia longispatha (Araceae) , LN 297100 428543, LGCh-825.10” (INBC). Allotype, female adult with larval and pupal exuviae on microscope slide, labeled as for holotype, but LGCh-825.04 (INBC). Paratypes: 6 ♂, each with pupal exuviae, 1 ♂ with larval and pupal exuviae, 5 ♀ each with pupal exuviae, 3 pupae, 7 larvae, Sendero Pajaro Sombrilla, Reserva Biológica Alberto Ml. Brenes, Angeles , San Ramón, Alajuela, Costa Rica, 9-II-2005 (2 ♂, 2 ♀, each with pupal exuviae, CNCI; remainder to INBC) ; 1 ♀, Sector la Peninsula, Arenal National Park, Costa Rica , 600m, 6–10-II-2000 ( INBC) ; 1 ♂, 3 ♀, each with pupal exuviae, 1 ♀, with larval and pupal exuviae, 5 fourth instar larvae, labeled as for holotype ( INBC) ; 1 ♂, Cerro Rincón, Corcovado National Park, Costa Rica , 745 m, 2-VI–31-VII-2002 ( INBC) ; 1 ♂, Cerro Nicuesa, Piedras Blancas, Golfito , Puntarenas, Costa Rica , 579 m, 28-XI-2000 – 3-II-2001 ( CNCI) ; 1 ♀, Send. Purruja, Est. Agujas, Rio Agujas , Peninsula de Osa , Costa Rica , 300 m, 10–20-VIII-1996 ( INBC) ; 1 ♀, Est. Agujas, Peninsula de Osa, Costa Rica , 300 m, 15-VII–15-VIII-1999 ( INBC) ; 1 ♀, as for previous locality but 250–350 m, 4–20-VI-1999 ( CNCI) ; 1 ♀, as for previous locality but 15-VII–15-VIII-1999 ( INBC) ; 1 ♀, as for previous locality but Los Charcos , 600 m, 15-V–15-VI-1999 ( INBC) ; 1 ♀, Est. Los Planes, Corcovado National Park, Costa Rica , 180 m, 23–24-VII-2002 ( INBC) ; 1 ♀, Send. a Sirena, Est. Los Patos , Corcovado National Park , Costa Rica , 100 m, 26-XII-2000 ( INBC) ; 4 ♀, 5 km W. Rincón, Aguabuena, Sierpe , Centro Juvenil Tropical , Costa Rica , 10-VIII- 2001 (2, INBC; 2, CNCI) ; 1 ♀, 2 km SE de Estación, Barbilla National Park, Turrialba, Cartago, Costa Rica , 500–600 m, 2-VII–19-VIII-2000 ( INBC) ; 1 ♀, Sendero Ron Ron, Estación Biológica Copal, Pejibaye , Cartago, Costa Rica , 1090 m, 3–14-IV-2005 ( INBC) ; 1 ♂, Turrialba, Costa Rica , XI-1922 ( USNM) ; 1 ♀, Est. Quebrada González, Braulio Carillo National Park, Pococi , Limón, Costa Rica , 400–500 m, 15-X-2002 ( INBC) ; 1 ♀, Sendero Espavel, Valle de la Estrella, Hitoy Cerere , Costa Rica , 560 m, 18–22-IX-2003 ( INBC) .

DERIVATION OF SPECIFIC EPITHET: Douglas A. Craig was on the author’s masters committee in 1975–78 and during that time and since has been a sounding board for my tenuous concepts, provided good advice, and shared a wealth of perspectives and stimulating ideas. It has always been a pleasure to work with him and this species is named to acknowledge his major contribution to my understanding of entomology, as well as recognizing his excellent contributions to Dipterology.