Corethrella (Corethrella) picticollis Edwards

Published, First, 2008, The Frog-Biting Midges of the World (Corethrellidae: Diptera), Zootaxa 1804, pp. 1-456 : 95-96

Corethrella (Corethrella) picticollis Edwards

Corethrella picticollis Edwards 1930:531 . Type locality: Lagos, Nigeria. Lectotype male adult, here designated (BMNH). Freeman 1962:43.

DIAGNOSIS: Male adult: only extant species of Corethrella in the Afrotropical Region with a midlength wing band (Fig. 62K), the hind tibia with discrete basal and apical dark pigmentation (as in Fig. 45D), with the apex of the aedeagus shallowly bifid and gonostylus with apical peg short and slender (Fig. 89A). Female adult: only extant species of Corethrella in the Afrotropical Region with a midlength wing band (Fig. 68H), with a wing length of 1.25–1.38 mm and the hind tibia with discrete basal and apical dark pigmentation ( Fig. 45D).

DESCRIPTION: Male adult. Descriptive statistics: see Tables 2–5. Head: Outline in anterior view laterally elongate (as in Fig. 8I). 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. 21E, sensilla coeloconica distributed as in Table 1; flagellomere 13 with welldeveloped apical bifurcation. Palpus pale; segment 3 of nearly constant width. Thorax (as in Fig. 45D): Uniformly medium brown. Posterior portion of dorsocentral row with single 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. 62K): 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 (darker anteriorly, posteriorly); veins (other than costa and wing margin) with well-developed scales. Halter pale, paler than scutellum. Legs (as in Fig. 45D): Medium brown, with apical ½–3/4 of hind femur pale, hind tibia pale with discrete basal, apical dark brown pigmentation; mid-, hind tarsi with at least tarsomeres 2–4 with slight 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. 77L): Light brown, with posterior margins of tergites 6, 7, segments 8–9 medium brown. Genitalia (Fig. 89A): Gonocoxite uniformly medium brown, strongly tapering; anteromedial area with spicules similar in length to those elsewhere on gonocoxite; with well-defined dorsal row of three setae, with setae 1, 2, 3 progressively thicker, with row restricted to dorsal portion of gonocoxite (2–3 small dorsomedial setae present, possibly part of row). With one dorsomedial stout seta, tapering from base. Gonostylus (partially extended) basal 2/3 straight, gently curved for apical 1/3, basal half thicker, tapering to apical half of more or less equal thickness, tapered apically; without subbasal seta; with short, thick apical seta. Aedeagus slender, elongate, tapering from base but with more abrupt narrowing subapically, rounded apically with bifid apex, 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; with flagellomeres as in Fig. 28B, sensilla coeloconica distributed as in Table 1. Clypeus ( Fig. 17 AE) squarish or somewhat wider than long. Mandible with small, pointed teeth. Palpus as in Fig. 34A. Wing (Fig. 68H). Legs ( Fig. 45D): As for male but apical 1/4–1/2 hind femur pale. Claws of each leg equal to those of others; equal on each leg, simple (without inner teeth). Abdomen: Medium brown with segments 8–9 dark brown; some with posterior margins of tergites 5–7 with darker pigmentation. Cercus dark brown.

Immatures. Unknown.

DISTRIBUTION AND BIONOMICS: Corethrella picticollis is known from Liberia, Ghana and Nigeria (Fig. 114) at altitudes ranging from 34–293 m. Specimens in Ghana have been collected using light traps.

TAXONOMIC DISCUSSION: Males and females were associated through the shared presence of a common pigmentation pattern and were collected together at two locations in Ghana.

Edwards (1930) based his description of this species on one male and two females without designating a holotype. I have chosen the male to be the lectotype and the two females as paralectotypes. The lectotype and one female paralectotype were originally on pins (with the male genitalia stained red and mounted on a piece of celluloid) and both are now on microscope slides. The second female paralectotype remains on the pin but is in very poor condition with only part of the thorax and one wing remaining.

The lectotype did not have a locality label but it is almost certain that it has been lost after Edwards (1930) described this species, as he specifically reported the locality and date as Lagos, Nigeria, 8-XI-1909. I did not reexamine two Ugandan males from nr. Kampala and Namanve reported by Freeman (1962) (and present in the BMNH) but it seems more likely, based on their distributions, that they are members of C. ugandensis .

MATERIAL EXAMINED: Lectotype, here designated, adult male on microscope slide, labeled “ Corethrella picticollis Edwards , Lectotype, desig. A. Borkent”, “ Corethrella picticollis Edw., F.W. Edwards. det. 1930", “ Syntype ”, “ Syntype Corethrella picticollis Edwards det. J.E. Chainey, 1995", “Type” ( BMNH). Paralectotypes: 2 ♀, Lagos, Nigeria, IX-1929 ( BMNH) . Other material: 2 ♀, Marshall , Liberia, 89 m, 29-XII-1951 ( USNM) ; 2 ♂, Bechem , Brong Afaho Region, Ghana, 293 m, 7-VIII-1991 ( BMNH) ; 1 ♂, 1 ♀, Assin Foso Cocoa Station , Central Region, Ghana, 26-?-1991 ( BMNH) ; 2 ♂, 1 ♀, Bieni Cocoa Station , Eastern Region, Ghana, 151 m, 24-X-1991 ( BMNH) .

DERIVATION OF SPECIFIC EPITHET: The name picticollis (painted, hill) probably refers to the variably patterned thorax evident in the pinned specimen and noted by Edwards (1930).