Corethrella (Corethrella) fuscifimbria 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 : 23-24

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

urn:lsid:zoobank.org:act:26B5C6CC-46FD-49D9-A1F3-DABA9BBBFB19

Fig. 9

Diagnosis

Female adult

Only extant species with the following combination of characters: clypeus squarish, bearing 2–3 setae ( Fig. 9B ); a complete coronal suture ( Fig. 9B ); thorax dark brown ( Fig. 9G ); wings with midlength band of dark scales on all veins and a band of dark scales on apex ( Fig. 9J ); halter pale ( Fig. 9G ); hind tibia with discrete apical and basal band of dark pigmentation ( Fig. 9F ); femora without scales; empodia with 4 branches; and abdominal segments I–VII uniformly pigmented ( Fig. 9L ).

Male

Unknown.

Etymology

The specific epithet – fuscifimbria – (from Latin, ‘ fuscus ’ = ‘dark’; ‘ fimbria ’ = ‘fringe’) is a reference to the dark scales on the apex of the wings.

Material examined

Holotype

BRAZIL – Bahia State • ♀, adult; Rio de Contas, Parque Natural Serra das Almas, “Brejo do junco” [reed marsh]; 13°32ʹ19ʺ S, 41°52ʹ36ʺ W; 1202 m a.s.l.; 3 Dec. 2019; A.P. Amaral leg.; frog-call trap (chorus); slide-mounted; MZUSP.

Paratypes

BRAZIL – Bahia State • 3 ♀♀, adults; same collection data as for holotype; CE-MHS • 1 ♀, adult; same collection data as for holotype, except 2 Dec. 2019; CE-MHS • 2 ♀♀, adults; Rio de Contas, RPPN Volta do Rio, streamside ; 13°32ʹ07ʺ S, 41°54ʹ44ʺ W; 1318 m a.s.l.; 1 Dec. 2019, A.P. Amaral leg.; frog-call trap ( Boana faber ); CE-MHS • 3 ♀♀, adults; same collection data as for holotype, except Vale do Queiroz , “mata de galeria” [riparian woodland]; 13°31ʹ28ʺ S, 41°57ʹ24ʺ W; 1579 m a.s.l.; 30 Nov. 2019; CE-MHS .

Description

Female adult (n = 10)

HEAD ( Fig. 9A ). Dark brown. Outline in anterior view moderately laterally elongate, about 1.39 (1.30– 1.59) times as wide as long. Coronal suture complete, reaching ventral margin of interocular space. Clypeus ( Fig. 9B ) square to slightly wide, 1.24 (1.11–1.43) times as wide as long, with 2–3 dorsal setae of equal thickness. Mandibles serrate. Palpus ( Fig. 9C ) slightly less pigmented than head, third segment with constant width, about 0.8 times length of fifth. Antenna ( Fig. 9D ): pedicel and flagellum uniformly dark brown, flagellomeres ( Fig. 9E ) I–III elongate. Flagellomere XIII apically bifurcated. Sensilla coeloconica distribution: 1(II, [VIII], IX–XIII), 4(I). Sensilla ( Fig. 9B ): Ocular row with 1 ventral, 1 more dorsal, and 13–16 thick setae from vertex to mid-posterior portion; without well-defined subocular row, few setae on vertex; postgenal row with 6–9 intermediate and about 6 slender setae on mid-posterior portion. With 2 ventromedial thick setae.

THORAX ( Fig. 9F–G ). Dark brown, with ventral portion of anepimeron and sclerites around wing pale. Prescutal suture elongate, almost reaching dorsocentral row of setae. Anterior anepisternum longitudinally divided by sinuous suture. Posterior anepisternum divided by a diagonal suture, forming a triangle at inferior portion, with thick anterodorsal margin. Sensilla ( Fig. 9H ): Antepronotum with 2 anterodorsal and 7–8 lateroventral slender setae. Postpronotum with 1 thick dorsal, 1 intermediate, and 2–6 slender setae more posteriorly. Scutum, prescutal area with about 9–13 slender/intermediate setae anteriorly grouped; 2 thick and 1 intermediate setae near prescutal suture, dorsoventrally aligned; 8–13 scattered slender/intermediate setae. Antealar area with 4–5 thick/intermediate setae dorsoventrally aligned anteriorly, 7–9 thick/intermediate setae more posteriorly, forming a U-shape; 15–18 slender setae spread from ventral to dorsal portion. Supraalar area with 2–3 thick setae aligned longitudinally, 8–13 slender ones surrounding; 3–5 intermediate setae more anteriorly. Dorsocentral row, posterior portion with group of 4–6 thick offset setae; 17–24 thick/intermediate and 21–34 slender setae completing row. Scutellum with 8–10 thick setae. Posterior anepisternum bare. Anepimeron with 9–11 slender setae.

WING ( Fig. 9I, J ). Light brown, with midlength band of dark scales present on all veins. With darker scales on apex, anterobasal region and posterobasal margin. Non-marginal veins with narrow scales. Halter pale. R 3 /R 1: 0.55 (0.50–0.58); R 2+3 /R 2: 0.61 (0.53–0.74).

LEGS ( Fig. 9F ). Dark brown. Hind tibia with discrete basal and apical pigmentation. Mid- and foretibiae apically darker. Tarsi uniformly light brown. Legs without scales. Midleg tarsomeres 1–3 with thick subapical setae. Tarsal claws of each leg equal to those of others; equal on each leg, simple. Empodium ( Fig. 9K ) slender, of intermediate length, with 4 branches.

ABDOMEN ( Fig. 9L ). Medium to dark brown, with segments VIII, IX, and cercus darker.

Male and immatures

Unknown.

Distribution and biology

Adult Corethrella fuscifimbria sp. nov. were collected with frog-call pan traps (playing a chorus of Boana faber , Physalaemus cuvieri and P. nanus ) in Rio de Contas municipality, Bahia, at altitudes ranging from 1202 to 1579 m a.s.l. in a large marsh area and in a streamside forest. Rio de Contas is located in the Espinhaço mountain range, a national hotspot for conservation, home to many endemic species. Even though the specimens were captured in large numbers with sound traps, attempts to collect immatures were unsuccessful. The attraction to frog-call traps and the serrate mandibles of females indicate that they feed on frog blood.

Remarks

The specimens of C. fuscifimbria sp. nov. keyed to C. orthicola Borkent, 2008 in Borkent (2008), but differed from it in the length of the coronal suture (short in C. orthicola ), distribution of sensilla coeloconica ( C. orthicola with one sensillum on each of flagellomeres I–II, VII–XIII), pigmentation pattern of the thorax, pigmentation of sternites I–II (darker than the remainder of sternites in C. orthicola ), and the presence of an apical band on the wing, the latter being a synapomorphy of the brakeleyi species group. In fact, C. fuscifimbria is very similar to C. ranapungens Borkent, 2008 , which belongs to the brakeleyi group, differing only by the lighter pigmentation of the halters, the discrete pigmentation on the hind tibia, and the empodia with 4 branches (2 in C. ranapungens ; Fig. 36C ). Collections near the type locality retrieved four specimens of C. ranapungens which precisely fit the species description, enabling the comparison and distinction of C. fuscifimbria , which would be otherwise problematic due to the somewhat subtle differences between these two species. Borkent (2008) pointed out that C. ranapungens was strikingly variable and likely the name represented more than one species.

Figures

Fig. 9. Corethrella fuscifimbria 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. L. Abdomen, lateral view. Scale bars: 0.1 mm.

Fig. 36. Corethrella ranapungens Borkent, 2008, female adult. A. Cranial setae, anterior and posterior views, and clypeus in anterior view. B. Thoracic setae, lateral view. C. Hind leg claw and empodium, lateral view.