Corethrella obtusa Amaral & Pinho, 2025

Corethrella obtusa Amaral & Pinho sp. nov.

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Figs. 7–8 View FIGURE 7 View FIGURE 8

Type material. Holotype: ♂ adult: COLOMBIA: Amazonas , Leticia, 11 km, Tanimboca Forest Reserve, 4°7'10"S, 69°57'4"W. 7–14.XI.2017, Malaise Trap, G. Kvifte leg. (Colo08) ( CEUA) GoogleMaps . Paratypes: ♂ adult: as holotype, except: (Colo06) ( PERC) ; ♂ adult: as holotype, except Cerca Viva Natural Reserve , 4°7'22"S, 69°56'53"W. 3–7.XI.2017 (Colo09) ( CEMHS) GoogleMaps .

Etymology. The specific epithet is a reference to the blunt (obtuse) dorsomedial seta of the gonocoxite.

Diagnosis. Adult male. Only extant species of Corethrella with antenna with one sensillum coeloconicum on flagellomeres II–III, VIII–XIII ( Fig. 7A View FIGURE 7 ); complete coronal suture; ocular row with one thick ventral seta ( Fig. 8A View FIGURE 8 ); palpus as pigmented as head, with third segment only slightly longer than fourth, fifth segments; wing with distinct midlength band of dark scales, with more basal dark scales on C, Sc, and M ( Fig. 7D View FIGURE 7 ); halter pale; gonocoxite with dorsomedial seta stout and apically blunt ( Fig. 8D View FIGURE 8 ).

Description

Adult male (n = 3).

Head ( Fig. 7A View FIGURE 7 ). Light brown. Outline of head in anterior view laterally elongate; head W/L 1.57–1.93. Coronal suture complete, reaching ventral margin of interocular space ( Fig. 8A View FIGURE 8 ). Clypeus nearly square, 1.12–1.13 times wider than long, with 1–2 dorsal setae ( Fig. 8A View FIGURE 8 ). Palpus with same degree of pigmentation as head; third segment roughly cylindrical, about 1.2 length of fifth. Mandibles not clearly visible, lacinia weakly sclerotized.Antenna ( Fig. 7A View FIGURE 7 ): pedicel medium brown, with at least one thicker, distinctive elongate dorsal seta; flagellum as dark as head; flagellomeres I–III moderately elongate, or I elongate, II–III moderately elongate; XI–XIII elongate; flagellomere XIII with apical bifurcation. Sensilla coeloconica distribution: 1(II–III, [VII], VIII–XIII), 2(I). Cranial sensilla ( Fig. 8A View FIGURE 8 ): Ocular row with 1 thick offset seta at ventral part; 13–14 thick setae extending to posterior part of head; vertex with few slender setae. Subocular row inconspicuous. Postgenal row with 6–9 intermediate setae. With 2 ventromedial thick setae.

Thorax ( Fig. 7B View FIGURE 7 ). Light/medium brown, with darker pigmentation on anterior portion of anepimeron and around anterior spiracle. Prescutal suture short, ending halfway towards dorsocentral row of setae ( Fig. 8B View FIGURE 8 ). Anterior anepisternum divided longitudinally by sinuous suture. Posterior anepisternum divided by a faint diagonal suture, inferior portion triangular with anterodorsal margin thick, ventral margin poorly defined. Sensilla ( Fig. 8B View FIGURE 8 ): Antepronotum with 4 thick, 2 slender ventral setae. Postpronotum with 1 thick dorsal seta, 1 intermediate, 2 slender more posteriorly. Scutum, prescutal area, about 4 slender/intermediate anterior setae, row of 3 thick setae dorsoventrally aligned near prescutal suture, about 4 intermediate surrounding. Antealar area anterior portion with 3–4 thick setae dorsoventrally aligned and with 6 intermediate/thick setae forming U-shape on ventral portion, about 10 slender setae scattered from ventral to dorsal portions. Supraalar area with 1–2 thick setae with about 16 slender/intermediate surrounding. Dorsocentral row, posterior part with cluster of 4 thick setae; about 15 thick, 14 intermediate setae completing the row. Scutellum with 14 thick setae. Posterior anepisternum without setae. Anepimeron with 4–5 slender setae.

Wings ( Fig. 7D View FIGURE 7 ). Light brown, with darker midlength band on all veins, subbasal spot on M, basal spot on C, Sc. Non-marginal veins with narrow scales. Apex of R 2 equal to apex of M 1. Halter lightly pigmented, distinctly lighter than scutellum. Wing length 0.96–1.05 mm. R 3 /R 1: 0.44–0.47. R 2+3 /R 2: 0.64–0.80.

Legs ( Fig. 7C View FIGURE 7 ). Light/medium brown, with distal 0.4 of hind femur pale; hind tibia with well-defined basal, apical bands of darker pigmentation. Legs without scales. Midleg tarsomeres 1–3 with thick subapical setae. Tarsal claws on foreleg unequal; mid-, hind leg equal; apically inserted. Empodium with intermediate thickness; intermediate length; with 5 bifid branches ( Fig. 8C View FIGURE 8 ). Apices of fore-, midtarsi not bilobed. Ta1/Ta2: 2.88–3.14. Ta3/Ta4: 0.81–0.98.

Abdomen ( Fig. 7E View FIGURE 7 ). Medium brown, with segment 9 somewhat more darkly pigmented.

Genitalia ( Fig. 7E View FIGURE 7 ). Gonocoxite ( Fig. 8D View FIGURE 8 ) brown at base, pale at apex; elongate; without distinctively elongate spicules on anteromedial area; dorsomedial row well-defined. With 5 dorsal to dorsomedial setae, somewhat thicker than other setae on gonocoxite, strongly tapering distally. With 1 dorsomedial stout seta, apically blunt, located at 0.26 gonocoxite length from base; without sclerotized plate at base. Gonostylus slender, curved subapically; subbasal seta simple, elongate; anteriorly located. Apical seta slender, elongate. Aedeagus elongate; fused apically, with pointed apex ( Fig. 8E View FIGURE 8 ).

Adult female: Unknown

Immatures: Unknown

Remarks. This species somewhat keys to couplets 84 or 96 - C. selvicola Lane in Amaral et al. (2023). It can be distinguished from C. selvicola by the elongate coronal suture; the abdominal segment IX somewhat more darkly pigmented than the VIII; and a blunt dorsomedial seta on the gonocoxite. Corethrella obtusa Amaral & Pinho sp. nov. has a combination of apomorphic character states shared with the clade which comprises the fulva, appendiculata , quadrivittata , brakeleyi, and wirthi species groups, according to the phylogeny of Borkent (2008). More inclusively, the presence of a sensillum coeloconicum on flagellomere III would place it among the wirthi group. This character is quite variable across the family and is considered a weak indication of relationship. Corethrella obtusa sp. nov. is similar to C. selvicola Lane and C. atricornis Borkent , differing from the first by having an elongate coronal suture, a distinct pigmentation pattern on the thorax, four posterior setae on the dorsocentral row, and a blunt dorsomedial seta on the gonocoxite. Corethrella atricornis is only known by female specimens, so the comparison is limited. Nevertheless, considering the sexual dimorphism and intraspecific variations observed in other species, C. obtusa sp. nov. may be distinguished by the shape of the palpus, its darker coloration, and by having 4–5 setae on the anepimeron ( 15 in C. atricornis ).