Corethrella (Corethrella) unifasciata Amaral & Pinho, 2023

Amaral, André P., Mariano, Rodolfo & Pinho, Luiz Carlos, 2023, Description of five new species of frog-biting midges (Diptera, Corethrellidae) from Brazil and examination of new morphological characters with utility for taxonomic and phylogenetic studies, European Journal of Taxonomy 874 (1), pp. 1-120 : 26-28

Corethrella (Corethrella) unifasciata Amaral & Pinho sp. nov.

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Fig. 10

Diagnosis

Female adult

Only extant species with the following combination of characters: most of the thorax pale, with katerpisternum, mediotergite, ventral portion of posterior anepisternum and anterodorsal region of anepimeron more darkly pigmented ( Fig. 10G ); hind tibia pale with darker apical band ( Fig. 10F ).

Etymology

The specific epithet – unifasciata – (from Latin, ‘ uno ’ = ‘one’; ‘ fascia ’ = ‘band’) is a reference to the pigmentation of the hind tibia, also present in related species.

Material examined

Holotype

BRAZIL – Bahia State • ♀, adult; Porto Seguro, RPPN Estação Veracel, “trilha escolar” [educational trail]; 16°23ʹ10ʺ S, 39°10ʹ11ʺ W; 89 m a.s.l.; 28 Aug. 2019; A.P. Amaral leg.; frog-call trap (chorus); MZUSP.

Paratype

BRAZIL – Bahia State • 1 ♀, adult; same collection data as for holotype, except mussununga; 16°21ʹ33ʺ S, 39°08ʹ15ʺ W; 72 m a.s.l.; 30 Aug. 2019; CE-MHS.

Description

Female adult (n = 2)

HEAD ( Fig. 10A ). Medium brown. Outline in anterior view laterally elongate, 1.41–1.45 times as wide as long. Coronal suture complete, reaching ventral margin of interocular space. Clypeus ( Fig. 10B ) wide, 1.15–1.27 times as wide as long, somewhat rounded, with 1 thick dorsal seta and 2–3 slightly less thick ones. Mandibles serrate. Palpus ( Fig. 10C ) pale, third segment with constant width, of about same length as fifth. Antenna ( Fig. 10D ): pedicel dark brown, flagellum pale from I–VII, dark brown from VIII–XIII; flagellomeres ( Fig. 10E ) I–III elongate. Flagellomere XIII with apical bifurcation. Sensilla coeloconica distribution: 1(II–III, VIII–IX, XII–XIII), 2([IX], X–XI, [XII]), 4(I). Sensilla ( Fig. 10B ): Ocular row with 2 thick offset setae at ventral part, 15–19 ones more dorsally, extending posteriorly to midlength. Without well-defined subocular row; vertex with numerous slender setae. Postgenal row with 9–10 intermediate setae, restricted to mid-posterior region. With 2–3 thick ventromedial setae.

THORAX ( Fig. 10F–G ). With following sclerites medium brown: proepisternum, antepronotum, ventral portion of posterior anepisternum, katepisternum, anterodorsal portion of anepimeron, ventral portion of scutum, mediotergite and coxae; elsewhere pale. Prescutal suture very short, barely visible. Anterior anepisternum divided longitudinally by sinuous suture. Posterior anepisternum divided by diagonal suture, forming a triangle at inferior portion, with anterodorsal margin thick. Sensilla ( Fig. 10H ): Antepronotum with 5–7 intermediate setae from anterolateral to posterior margins. Postpronotum with 1 thick dorsal seta, 2–3 intermediate posterior, and 0–1 slender posteroventral setae. Scutum, prescutal area 4–5 thick posterior, dorsoventrally aligned setae; 5–6 intermediate and 12–13 slender setae more anteriorly, merging with anterior portion of dorsocentral row; about 14 slender posterodorsal setae, extending to antealar area. Antealar area, anterior portion with 3–4 thick and 2–4 intermediate setae dorsoventrally aligned; more posteriorly, 2–4 thick and 8–10 intermediate setae forming a U-shape just above paranotal suture; about 50 slender setae spread from ventral to dorsal portions. Supraalar area, 4–6 thick/intermediate setae anteroposteriorly aligned, about 45 slender setae spread from ventral to dorsal portions. Dorsocentral row, posterior portion with group of 9–10 thick and 3 slender setae; 12 thick and about 60 slender/intermediate setae completing the row. Scutellum with 14 thick setae. Posterior anepisternum bare. Anepimeron with 15–16 slender setae posterodorsally located.

WING ( Fig. 10I–J ). Light brown, non-marginal veins with narrow scales. Midlength band of darker scales present, missing on R 4+5 and CuP; distally dislocated on apex of CuA; darker on C, Sc, R 1, and M 4. Apex of R 2 basal to apex of M 1. Halter as pale as scutellum. R 3 /R 1: 0.48–0.49; R 2+3 /R 2: 0.55–0.57.

LEGS ( Fig. 10F ). Light brown. Fore femur basal 0.6 and hind femur basal 0.3 darker; midfemur with apex slightly paler. Base of hind tibia light brown; all tibiae with dark bands on apex. Tarsomeres 2–5 somewhat darker. Legs without scales. Midleg tarsomeres 1–3 with large subapical setae. Empodium ( Fig. 10K ) of intermediate length and thickness, with 6 branches. Ta1/Ta2: 2.79–2.95; Ta3/Ta4: 1.19– 1.19.

ABDOMEN ( Fig. 10L ). Light to medium brown, with segments VIII, IX, and cercus darker.

Male and immatures

Unknown.

Distribution and biology

The two females were collected at two neighboring localities at the RPPN Estação Veracel, Porto Seguro, Bahia, at altitudes of 72 m a.s.l. and 89 m a.s.l. with frog-call traps playing a chorus of Atlantic forest frogs ( Boana faber , Physalaemus cuvieri and P. nanus ). Extensive efforts to collect immatures were made in the areas, in ground pools and phytotelmata, retrieving immatures of other species, but not C. unifasciata sp. nov.

The attraction to frog-call traps and the serrate mandibles indicate that females feed on frog blood in nature.

Remarks

Corethrella unifasciata sp. nov., only known for females, has character states shared by the clade formed by C. lepida Borkent, 2008 and C. caribbeana Borkent, 2008 , which have the apex of R 2 more basal than the apex of M 1, the ventral portion of the ocular row with two stout setae (four setae on the ventromedial area of the frons in Borkent’s terminology), the posterior end of the dorsocentral row with a group of more than three thick setae, and the hind tibia basally pale. This species can be distinguished from C. lepida by the presence of two sensilla coeloconica on each of flagellomeres X–XI, the ocular row of setae extending to the mid-posterior part of the head, the presence of 9–10 thick offset setae on the posterior portion of the dorsocentral row, the antealar and supraalar areas with numerous slender setae, the wing band without dark scales on R 4+5, and the peculiar pattern of thoracic pigmentation. This species differs from C. caribbeana by the following features: longer flagellomeres I–III, palpus without a pigmented segment V, posterior portion of dorsocentral row with more than 5 setae, patterns of wing pigmentation, and thoracic pigmentation.

Complementary descriptions and diagnoses

Emended descriptions of adults and immatures are given for 33 Corethrella species , based on additional material collected in Brazil, in order to detail new characters (see Morphology remarks, below).Diagnoses for immatures are provided. References for descriptions and pertinent taxonomic publications are found in Appendix 1. Species are ordered according to phylogenetic affinities.

Figures

Fig. 10. Corethrella unifasciata sp. nov., female adult, holotype (MZUSP). A. Head, anterior view. B. Cranial setae, anterior and posterior views, and clypeus in anterior view. C. Left palpus, lateral view. D. Antenna, lateral view. E. Pedicel and flagellomeres, lateral view. F. Thorax and legs, lateral view. G. Detail of thorax, lateral view. H. Thoracic setae, lateral view. I. Wing veins. J. Wing. K. Hind leg claw and empodium, lateral view. L. Abdomen, dorsal view. Scale bars: 0.1 mm.