Corethrella (Corethrella) unizona Borkent, Grafe

Borkent, Art & Grafe, Ulmar, 2012, The Frog-Biting Midges of Borneo — From Two to Eleven Species (Corethrellidae: Diptera), Zootaxa 3279, pp. 1-45 : 13

Corethrella (Corethrella) unizona Borkent, Grafe & Miyagi, new species

( Figs. 5 A, 6F, 8G, 10B, 12G, 13F, 14A)

DIAGNOSIS: Male adult. Unknown. Female adult. Only extant species of Corethrella in the Palaearctic, Oriental, Oceanian and northern Australasian Regions with the combination of the palpus and clypeus equally dark brown ( Fig. 6 F), a single, midlength wing band ( Fig. 12G ), tergites 2–6 uniformly brown ( Fig. 13F ), midfemur either uniformly brown or lighter apically (non-discrete), and hind tibia with dark pigmentation at apex (in some very light pigmentation basally) ( Fig. 10B ). Only extant species in Borneo with the combination of the palpus and clypeus equally dark brown, a single, midlength wing band, hind tibia with dark pigmentation at apex (in some very light pigmentation basally), and with tergites 2–6 uniformly brown.

DESCRIPTION: Male adult. Unknown. Female adult. Descriptive statistics: See Tables 1 –5. Head: Outline in anterior view somewhat circular ( Fig. 6 F). Coronal suture elongate, extending ventrally past ommatidia. Two large setae on frons between ventromedial area of ommatidia. Antenna uniformly medium brown; pedicel with distinctive elongate, stout setae. Antennal flagellomeres as in Fig. 8 G; sensilla coeloconica on flagellomeres 1, 9–13, flagellomeres 1 with several, (9), 10–12 with 2 sensilla; flagellomere 13 with well-developed apical bifurcation. Clypeus ( Fig. 6 F) wide. Mandible with very small, pointed teeth. Palpus ( Fig. 6 F) medium brown; segment 3 swollen apically. Thorax ( Fig. 10B ): Uniformly medium brown. Posterior portion of dorsocentral row with 2 elongate setae situated somewhat lateral to one another. Prescutal suture elongate, thick, interrupted by area of pale cuticle, extending nearly 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. 12G ): Apex of R2 slightly distal to apex of M1. Anterior margin with differently, discretely pigmented scales (indicating anterior margin of basal, midlength bands), with basal, midlength bands; veins (other than costa and wing margin) with well-developed scales. Halter medium brown, equal to scutellum. Legs ( Fig. 10B ): Medium brown, with poorly defined paler areas on apex of fore-, midfemur and base of fore-, midtibia in some, with paler area on apical about 0.4–0.7 of hind femur, hind tibia in some with narrow basal band of darker pigmentation, very apex of hind tibia with dark pigmentation. With only slender setae, lacking scales. 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 slender. Abdomen ( Fig. 13F ): Uniformly medium brown, with segments 8–9. Cercus darker brown.

Immature stages. Unknown.

DISTRIBUTION AND BIONOMICS: Corethrella unizona is known from female specimens from one locality in Brunei and two closely approximated sites in Sarawak 30–1083 m ( Fig. 14A ). Habitats include lowland peat swamp and mid-elevation peat swamp or a nearby river ( Fig. 1 G). Specimens were collected with frog-call traps, always in very low numbers on a given evening and have not been observed feeding on frogs (Table 7).

TAXONOMIC DISCUSSION: Corethrella unizona belongs to the clade defined by synapomorphies 39–44 ( Borkent 2008: fig. 141) ( Fig. 19 ). It has all these features except for 44 which could not be scored because it depends on knowledge of the male (unknown for C. unizona ). There were no further features which would allow for further placement phylogenetically.

TYPES: Holotype, female adult on microscope slide, labeled " HOLOTYPE Corethrella unizona Borkent, Grafe and Miyagi", " 15 km S. Liang, Brunei, 7-VI-2007; frog-call trap with synthetic tone + 200, U. Grafe; 76-4/1 DNA extracted", "076-4/1 080108 " (CNCI). Paratypes on microscope slides: 1 Ƥ, labeled as for holotype but 22- V-2007, 49-3/1, 49-3/1 301107 (UBD); 15 Ƥ, Bario, Sarawak, Malaysia, 1060 m, on several dates: 29-VIII-2008, 2, 5, 6-IX-2007, 5,10- IX-2009 (14, CNCI; 1, UBD). Paratype on pin: 1 Ƥ, Pa Umor, 5 km E. Bario, Sarawak, Malaysia, 1083 m, 25-XI-2010 (CNCI).

DERIVATION OF SPECIFIC EPITHET: The name unizona (single belt) refers to the single wing band of females of this species.

Figures

FIGURE 1. Habitats from which Corethrella adults were collected with a frog-call trap in Brunei (species collected given in parentheses). A. 12 km S. Liang, Brunei (C. tigrina, C. lutea, C. calathicola, C. pauciseta, C. gilva) (authors, for scale). B. Nepenthes ampullaria, 12 km S. Liang, Brunei (C. calathicola). C. 12.5 km S. Liang, Brunei (same species as for A) (first author, for scale). D. 20 km N. Labi, Luagan Lalak Forestry Rec. Site, Brunei (C. lutea). E. Belalong River, Kuala Belalong Field Studies Centre, Brunei (C. lutea, C. bipigmenta, C. mitra). F. Sungai Esu, Ulu Temburong NP, Brunei (C. tigrina, C. bipigmenta, C. mitra) (first author's wife Annette, for scale). G. Pa Umor, 5 km E. Bario (C. bicincta, C. unizona).

FIGURE 5. Habitus of adult female Corethrella, in lateral view, all in alcohol.

FIGURE 6. Head capsules of female Corethrella, anterior view.

FIGURE 8. Antennae and male genitalia of Corethrella. A – K. Antennae of female Corethrella. L. Antenna of male C. tigrina. M. Male genitalia of C. tigrina, dorsal view; parts drawn in proportion to each other.

FIGURE 19. Phylogenetic relationships of Corethrella from Borneo to other species and showing their distributions. Numbers refer to character states given in Borkent (2008). Evidence for cladistic relationships given in Borkent (2008).

FIGURE 12. A – K. Wings of female Corethrella.

FIGURE 13. A – J. Abdomens of female Corethrella, ventral view.

FIGURE 10. A – D. Thoraces and legs of female Corethrella, lateral view; slide-mounted.

FIGURE 14. A – B. Distributions of species of Corethrella from Borneo.