Corethrella (Corethrella) kerrvillensis (Stone)

Published, First, 2008, The Frog-Biting Midges of the World (Corethrellidae: Diptera), Zootaxa 1804, pp. 1-456 : 62-63

Corethrella (Corethrella) kerrvillensis (Stone)

Lutzomiops kerrvillensis Stone 1965:231 . Type locality: Kerrville, Kerr Co., Texas, U.S.A. Holotype ♀ (USNM). Corethrella kerrvillensis: Borkent 1993:10 .

DIAGNOSIS: Male adult: unknown. Female adult: only extant species of Corethrella with a plain wing (Fig. 67D), and the pleura of the thorax nearly completely pale with a patch of dark pigmentation only on the dorsal portion of the katepisternum and on the metanepisternum ( Fig. 40D).

DESCRIPTION: Male adult. Unknown. Female adult: Descriptive statistics: see Tables 6–11. Head: Outline in anterior view nearly circular ( Fig. 7B). Coronal suture absent ( Fig. 16C). Two large setae on frons between ventromedial area of ommatida ( Fig. 16C). Antenna uniformly brown; pedicel without distinctive, more elongate, stout, dorsal or dorsolateral setae; flagellomeres as in Fig. 26I, sensilla coeloconica distributed as in Table 1; flagellomere 13 with well-developed apical bifurcation. Clypeus ( Fig. 17M) squarish. Mandible with small, pointed teeth. Palpus ( Fig. 33O) brown; segment 3 swollen apically. Thorax ( Fig. 40D): Scutum light brown with darker pigmentation on lateral vitta, are just dorsal to paratergite and anterior margin; pleuron pale with patch of darker pigmentation on dorsal portion of katepisternum, metanepisternum. 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 division uncertain. Ventral portion of posterior anepisternum not differentiated from dorsal portion, pale. Wing (Fig. 67D): Apex of R 2 basal to apex of M 1. Plain, without pattern of pigmented veins and/or scales; veins (other than costa and wing margin) with only setae. Halter light brown, equal in pigmentation to scutellum. Legs ( Fig. 40D): Nearly uniformly light brown, with bases of femora 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. Claws of each leg equal to those of others; equal on each leg, simple (without inner teeth). Empodia thick. Abdomen: Segments uniformly medium brown.

Immatures. Unknown (but see below).

DISTRIBUTION AND BIONOMICS: Corethrella kerrvillensis is known only from the type locality in Kerrville , Texas, USA (Fig. 117A) at an altitude of 492 m. It is unknown how the specimens were collected .

Fourth instar Corethrella larvae have been collected from the hyporheic zone of small streams in Arizona ( Boulton et al. 1992) and from Barton Creek, Travis Co., Texas but were not reared. The larvae key to C. laneana in McKeever and French (1991b) but differ from that species by their very pale color, slightly plumose lateral head capsule spines and lack of dorsal plaques on abdominal segments. There are two named species of Corethrella known as adults which occur or potentially occur in this area. Corethrella appendiculata from Arizona has been reared from a treehole and a stream pool and the larva of this species clearly differs from those at hand. The immature stages of C. kerrvillensis are unknown and these pale larvae from the hyporheic may belong to this species or to a presently unknown species. It would be fascinating to rear some live specimens of these larvae to confirm their identity and to study their peculiar biology in the hyporheic, certainly an unusual habitat for a member of the Culicoidea with a functional siphon.

TAXONOMIC DISCUSSION: The holotype was originally on a pin and is now on a microscope slide. I have added the label “ Corethrella kerrvillensis ” to the holotype to clarify its current, correct name. Stone (1965) noted the presence of four female paratypes but these could not be located at the USNM (T. Gaffigan pers. comm.). However, I did examine three pinned paratypes at the USNM in 1976 and they may yet be located there.

MATERIAL EXAMINED: Holotype, adult female on microscope slide, labeled “ HOLOTYPE Lutzomiops kervillensis (sic) Stone USNM 67423, Kerrville, Tex, May, 1954, L.J. Bottimer”, “ Corethrella kerrvillensis ” (USNM) .

DERIVATION OF SPECIFIC EPITHET: The name kerrvillensis refers to the type locality in Kerrville , Texas .