Corethrella cambirela, Amaral & Mariano & Pinho, 2019

Amaral, André P., Mariano, Rodolfo & Pinho, Luiz Carlos, 2019, Four new species and some new records of Brazilian frog-biting midges (Diptera Corethrellidae), Zootaxa 4706 (1), pp. 103-120 : 113-116

Corethrella cambirela sp. n.

( Figures 6–8 )

Type material. Holotype, male adult, slide mounted: “HOLÓTIPO Corehtrella cambirela Amaral, Mariano & Pinho ♂, BR SC SA da Imperatriz, Plaza Caldas – PEST, S27°44’30” W48°48’25” 424m, 09-10.VIII.2017 – CDC trap, LC PINHO et al. leg.” ( MZUSP) . Allotype, adult female slide mounted: “ALÓTIPO Corehtrella cambirela Amaral, Mariano & Pinho ♀, BR SC SA da Imperatriz, Plaza Caldas – PEST, S27°44’35” W48°48’27” 433m, 25.IV.2013 – frog call trap (P. lateristriga) - 2ª3, A AMBROZIO-ASSIS leg.” ( MZUSP) . Paratypes: 4 adult males, as holotype

( UFSC). 1 adult female as allotype, except: “ 31.III.2013 – frog call trap (Hypsiboas poaju)” ( UFSC) .

Etymology. The specific epithet is a Tupi-Guarani word which the native people used to refer to the type locality, Santo Amaro da Imperatriz. The name is to be regarded as a noun in apposition.

Diagnostic characters. This species differs from other extant Corethrella by the following combination of characters (Adult females and males): Ventral portion of posterior anepisternum triangular shaped with anterodorsal margin thick and well developed; wings uniformly pigmented; legs almost uniformly pigmented, with apex of fore- and hind tibiae slightly darker; two thick setae on frons, near ventral margin of eye bridge; foreleg (only in males) with tarsomere 3 shorter than 4.

Description. Adult male (n=5). ( Tables 1 , 2 , Figs. 6 , 7 A–C)

Head ( Fig. 6A ). Broad in anterior view. Coronal suture elongate, reaching ventral margin of eye bridge. Two thick setae on frons. Palpus (as in Fig. 7D ) same color as head with 3rd segment with about constant width. Clypeus ( Fig. 7A ) square, with one central seta on dorsal surface. Antenna ( Fig. 7F ) uniformly light brown with flagellomere 13 bifurcated at the apex. Sensilla coeloconica distributed according to table 1.

Thorax ( Fig. 6B ). Uniformly medium brown, with paler sclerites around wing base. Prescutal suture elongate, almost reaching dorsocentral row of setae. Posterior portion of dorsocentral row with group of three setae. Anterior anepisternum divided longitudinally by a senoidal suture, posterior anepisternum divided by a diagonal suture, forming a triangle at inferior portion with darker pigmentation, anterodorsal margin thick. Anepimeron with six setae.

Wings (as in Fig. 8C ). Almost uniformly light brown to yellowish, with anterior veins slightly more pigmented. Apex of R 2 basal to apex of M 1. Halter slightly less pigmented than scutellum.

Legs (as in Fig. 8B ). Uniformly pigmented, except for apex of hind and foretibiae slightly darker. Without scales. Mid and hind tarsal claws equal, foreleg tarsal claws unequal, larger than hind and mid claws, apically inserted. Empodia (as in Fig. 7G ) with similar thickness to apical setae of last tarsomeres, with length similar to the average diameter of last tarsomeres, with 3 bifid branches.

Abdomen ( Fig. 6C ). Segments 1–7, 9 uniformly medium brown, segment 8 pale.

Genitalia ( Fig. 6C , 7B, C ). Gonocoxite ( Fig. 7B ) medium brown, width roughly constant; dorsal row with five setae a little thicker than the others; dorsomedial seta bold, with constant thickness on almost all its length, taper- ing near apex. Gonostylus slender, of constant width, straight throughout 2/3 of its extension, bending on last third, tapering subapically; subbasal seta thin, located anteroventrally, at 0.18 of gonostylus, length about 0.40 of gonostylus; apical seta (apparently missing in one individual) robust, elongate, divided (bifid or trifid). Aedeagus ( Fig. 7C ) elongate, tapering near a pointed apex; margins not fused.

Adult female: (n=2) ( Tables 1 , 2 , Figs. 7 D–F, 8) as for male, except:

Head ( Fig. 8A ). Coronal suture elongate, reaching ventral margin of eye bridge or a little further than halfway to that. Palpus ( Fig. 7D ) lightly pigmented. Clypeus ( Fig. 7E ) somewhat broader than long, 3–4 setae on dorsal surface. Sensilla coeloconica distributed according to table 1.

Thorax ( Fig. 8B ). Posterior portion of dorsocentral row with four setae placed laterally to one another. Anepimeron with 6–12 setae.

Legs ( Fig. 8B ). Tarsal claws equal, apically inserted.

Abdomen ( Fig. 8D ). Segments 1–7 uniformly medium brown, segments 8, 9 and cercus somewhat darker.

Immatures. Unknown.

Distribution and biology. This species is known from two females collected in frog-call traps playing the call of Physalaemus lateristriga (Steindachner) and Boana poaju Garcia, Peixoto, & Haddad, and five males collected using a CDC trap. So far this species is restricted to Serra do Tabuleiro State Park, in Santo Amaro da Imperatriz, SC, at elevations of 425– 434 m.

Physalaemus lateristriga is a ground dwelling frog found in southern São Paulo, Paraná and Santa Catarina states. Boana poaju is a tree frog endemic to three municipalities of east Santa Catarina. This species of Corethrella has been caught during a study using frog call traps at 0.5m from the ground, broadcasting the calls of six frog species, totalling 360 hours of trapping (two specimens identified as Corethrella sp. 2 in Ambrozio-Assis et al., 2018). It is noteworthy that these midges were attracted by the calls of only those two species of frogs, which could mean an acoustic preference. Unfortunately, the sample is too small to draw any conclusions on this matter.

Taxonomic discussion. The position of this species in the phylogeny of Corethrellidae is somewhat uncertain. Based on the synapomorphies delineated by Borkent (2008), Corethrella cambirela sp. n. fits somewhere among the fulva or wirthi species groups. Male abdominal segment 8 paler than both 7 and 9 is synapomorphy of all members of fulva group, except C. fuscipalpis Borkent , and is present in C. cambirela sp. n. That would place C. cambirela sp. n. in a polytomy at the base of fulva group, after the node that separates C. fuscipalpis from the other species. Corethrella cambirela sp. n. also shares a synapomorphy with wirthi group members – presence of a sensillum coeloconicum in the third flagellomere of the female antenna. Borkent considers this character a weaker indicator of relationship because it is homoplastic throughout the phylogeny. New phylogenetic analyses including all known species and additional evidence are needed to securely place C. cambirela sp. n. Males and females were associated by shared diagnostic characters of pigmentation patterns of wings and legs, thoracic sclerites and the setae on frons, as well as the collecting site.

Figures

FIGURE 6. Corethrella cambirela sp. n., adult male. A, head in anterior view. B, thorax in lateral view. C, tergites 6–9 and genitalia.

FIGURE 7. Corethrella cambirela sp. n., adult male (A–C) and female (D–G).A, clypeus in dorsal view. B, 9th abdominal segment, gonocoxite and gonostylus in dorsal view. C, aedeagus. D, palpus. E, clypeus in dorsal view. F, tarsal claw and empodium. G, antennal flagellum.

FIGURE 8. Corethrella cambirela sp. n., adult female. A, head in anterior view. B, thorax and legs in lateral view. C, wing. D, abdomen in lateral view.