Corethrella (Corethrella) nudistyla Borkent and Szadziewski

Published, First, 2008, The Frog-Biting Midges of the World (Corethrellidae: Diptera), Zootaxa 1804, pp. 1-456 : 204-205

Corethrella (Corethrella) nudistyla Borkent and Szadziewski

Corethrella nudistyla Borkent and Szadziewski 1992:460 . Type-locality: Dominican Republic. Holotype ♂ (AMNH).

DIAGNOSIS: Male adult: only fossil species of Corethrella with slender scales on midfemur (as in Fig. 74A) and with elongate R 2 and R 3 (as in Fig. 62A). Female adult: unknown.

DESCRIPTION: Male adult. Habitus as in Fig. 113C. Descriptive statistics: see Tables 2–5. Head: Outline in anterior view laterally elongate (as in Fig. 7G). Number of large setae on frons between ventromedial area of ommatida uncertain. Antenna: pedicel pedicel with at least one distinctive, more elongate, stout, dorsal or dorsolateral seta; flagellomeres as in Fig. 25F; sensilla coeloconica on flagellomeres 1, 9–13, flagellomere 1 with two sensilla coeloconica, others with one each; flagellomere 13 with well-developed apical bifurcation. Palpus with segment 3 somewhat swollen at or near midlength. Thorax: Posterior portion of dorsocentral row somewhat uncertain but probably with 3 elongate setae situated somewhat lateral to one another. Prescutal suture uncertain. Shapes of pleurites uncertain. Wing: Appressed against abdomen but generally similar to those of other Corethrella ; veins (other than costa and wing margin) with well-developed scales. Other details uncertain. Legs: With some thick setae on midfemur, slender on other legs (mostly denuded) (also scales in patch of whip-like setae on posterior portion of hind tibia) Anterior claws of foreleg without a basal prong. Midleg with thick, subapical setae on each of at least tarsomeres 1–3. Apex of foreleg fifth tarsomeres undivided, with claws slightly subapical to apical. Apex of midleg fifth tarsomere absent. Foreleg claws unequal. Mid-, hind leg claws absent. Foreleg third tarsomere longer than fourth tarsomere. Empodia not visible. Genitalia ( Fig. 2C in Borkent and Szadziewski 1992): Gonocoxite gently tapering; anteromedial area with spicules similar in length to those elsewhere on gonocoxite; with well-defined dorsal row of setae, with setae 2, 3, 4 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 (Fig. 99B) (in retracted position) evenly curved, slender, slender at midlength, tapered apically; one elongate, slender subbasal seta, situated anteriorly; apical seta slender, elongate, simple. Aedeagus mostly not visible, pointed apically.

Female adult and immatures. Unknown.

DISTRIBUTION AND BIONOMICS: Corethrella nudistyla is known only from Dominican amber (Fig. 139), dated at 19 million years old. Part of a female Psychodidae was also in the amber bearing the holotype.

TAXONOMIC DISCUSSION: The state of the specimen was described by Borkent and Szadziewski (1992). The specimen was further ground to enhance visibility. Contrary to Borkent and Szadziewski (1992), the male does have a subbasal seta on the gonostylus (hence the species is poorly named). In addition, an elongate, slender seta was visible at the apex of the gonostylus.

There are three female Corethrella in the AMNH, any of which may or may not be the female of C. nudistyla (DR-8-103, DR-14-720, DR-14-999). Each was in excellent condition, mostly opaque and difficult, therefore, to see some features of taxonomic importance (DR-8-103 is shown in Fig. 113D). The shape of their flagellomeres and palpal segments were similar. I did not consider them worth describing and naming because they provide so little information and could not be distinguished from numbers of extant species (especially considering that their original pigmentation is unknown). A fourth specimen (DR-13, AMNH), had a somewhat longer first antennal flagellomere and may represent another species but, again, such small differences provide little taxonomic information. All of these four females provide no more phylogenetic information than is available from the male holotype of C. nudistyla .

MATERIAL EXAMINED: Male adult in amber mounted in Canada Balsam on a microscope slide, labeled " HOLOTYPE Corethrella nudistyla Borkent and Szadziewski ", "Dominican amber, Jorge Wunderlich, June 1989, AMNH No. W-DR-46-b" ( AMNH) .

DERIVATION OF SPECIFIC EPITHET: The name nudistyla (bare, stylus) refers to the bare gonostylus originally (but mistakenly) thought to present in this species.