Alavesia leukoprosopa, Amorim & Riccardi & Rafael, 2020

Amorim, Dalton De Souza, Riccardi, Paula Raile & Rafael, José Albertino, 2020, First known extant species of Alavesia (Diptera: Atelestidae) in the Neotropical region: Alavesia leukoprosopa, sp. nov., from the southern Atlantic Forest, Brazil, American Museum Novitates 2020 (3962), pp. 1-12 : 3-9

Alavesia leukoprosopa , new species

Figures 1–4

DIAGNOSIS: Postpedicel slightly longer than scutum; face with whitish pruinosity; thorax dark, with a whitish pruinosity; head and thorax setulae pale; legs yellow; M 1+2 slightly sinuose along its length; ventrolateral of epandrium longitudinally sclerotized (fig. 4D, arrow); hypoproct longer than cercus; postgonites not jointed mesally, long, curved anteriorly; hypandrium indistinct.

DESCRIPTION: Male. Body length, 2.2 mm (fig. 1A). Head (figs. 1B–C): Frons black, with some grayish pruinosity, face whitish with dense white pruinosity, occiput black on dorsal half, thinly pruinose, grayish on ventral half, more densely pruinose. Gena very narrow. Ocelli on slightly projected vertex, mid ocelli only slightly displaced anteriorly in relation to lateral ocelli. Frons without setae, occiput with crown of yellowish postocular setae, face without setae. Eye bare; eyes dichoptic, large, with a rather metallic reddish color. Scape whitish, pedicel pale yellow, postpedicel dark brown. Postpedicel greatly lengthened, longer than scutum; stylus short, postpedicel about 5.8 length of stylus (fig. 3B). Maxillary palpus whitish, close to each other at tip; labellum light brownish yellow at base, whitish toward apex; labrum slender, elongate. Prementum well developed, whitish, setose.

Thorax (figs. 2A–B): Scutum and scutellum black, entirely covered with scattered pruinosity, denser on postpronotal lobe; 3–5 rows of short acrostichals clearly separated from 4–6 rows of short dorsocentral setae; pair of strong notopleurals, pair of long postalars, and an irregular row of stronger postsutural. Antepronotum blackish, proepisternum ochre-yellow. Anepisternum blackish; katepisternum mostly ochreous yellow, with small dorsoposterior brownish mark. Anepimeron blackish, with brownish area along meso-dorsal suture, katepimeron reaching ventral margin of thoracic pleura, weakly sclerotized, cream-yellow. Meron brownish yellow, dark brown along contact with metepisternum. Metepisternum blackish brown, metepimeron dirty yellow, darker dorsally. Laterotergite and mediotergite blackish brown. Elongate membranous area between anepisternum and katepisternum (fig. 2A, seta). Postpronotum densely microtrichose. One pale proepisternal seta present. Anepisternum densely pruinose, bare of setae; katepisternum shiny, no pruinosity or setae. Anepimeron, katepimeron, metepisternum, metepimeron, laterotergite and mediotergite pruinose, devoid of setae. Meron thinly pruinose, without setae. Halter stalk light brown, knob whitish, without setae.

Legs (fig. 1A, 3C–D): Coxae whitish yellow, forecoxa lighter, femora light brownish yellow, front and mid tibiae light brownish yellow, hind tibia darker, tarsi brownish yellow, darker towards apex. Femora with longitudinal area devoid of setulae, but no furrow; tibiae with rows of palisades with furrows in between. Hind tibia modified, more sclerotized than front and mid tibiae, with conspicuous sensorial organ dorsally on basal fourth, bearing ellipsoidal opening (fig. 3D).

Wing (fig. 3A): Length, 1.5 mm. Rather short compared to other congeneric species, oval shaped. Costal sections 1–4: 10; 1.5; 6; 3. C without spines. H present, weakly developed, Sc relatively long, extending beyond level of r-m, but incomplete; R 1 ending at distal third of wing, with one basal (fig. 3A, arrow) and two distal sensorial pits; R 2+3 ending at C slightly beyond tip of R 1. R 4+5 reaching C well before tip of wing, with three distal sensorial pits; M 1+2 almost as sclerotized as R 4+5, slightly sinuous along its length; cell dm present, small, restrict to basal third of wing, cells br and bm also short; dm-cu connecting M 1+2 to M 4, nearly transverse. Cell cua short, CuA+CuP reaching wing margin; long conspicuous anal fold almost reaching wing margin.

Abdomen (fig. 1A): Tergites 1–5 blackish brown medially, yellowish at lateral margins, sternites 1–5 pale brownish yellow. Tergites 6–7 more sclerotized along posterior margin, rather dark brown; tergite 8 membranous, slender, bare of setation.

Terminalia (figs. 4A–D): Hypandrium not discernible. Gonocoxal apodeme slender and greatly lengthened rod-like process, as long as ejaculatory apodeme, narrow in ventral view. Postgonites not joined medially, striplike, very long and bent anteriorly. Phallus tube-like, short, apex arched ventrally; ejaculatory apodeme long, articulated at base of phallus, posterior end slightly broadened. Epandrium U-shaped, with slender dorsal bridge anteriorly to cerci; setae concentrated along ventro-lateral margin; ventrolateral edge longitudinally sclerotized (fig. 4D, arrow), basally attached to epandrium, projected apically. Surstylus subapical, divided into pair of pointed lobes, each dorsal lobe with pair of setae along inner margin. Hypoproct longer than cercus, with setulae. Cercus sclerotized, ovoid, setose.

Female: Unknown.

TYPE MATERIAL: Holotype male, BRAZIL, São Paulo, Ribeirão Preto, University of São Paulo – campus of Ribeirão Preto , in front Guest House , S21°09′54″ W47°50′56″, 593 m, Malaise trap, 19.xi-3.xii.2019, P. R. Riccardi and H.F. Flores leg. [ MZUSP].

ETYMOLOGY: The specific epithet of the species name refers to the face (Greek, prosopa) with white (Greek, leukos) pruinosity in the described species.

REMARKS: This Neotropical representative of Alavesia differs in significant details from both known extant species described from Namibia. The postpedicel is longer than in both extant species of the genus. The scutum is yellow in A. brandbergensis , and black in A. daura and A. leukoprosopa , sp. nov. As in A. brandbergensis , the legs in A. leukoprosopa are yellowish, without the dark apex of mid and hind tibiae in A. daura . Compared to A. daura , the wing shape is more rounded and the venation of the Neotropical species has a slightly wider cell c and a more slender cell r 1. Although Tergite 8 is about the same width, it is more membranous than in A. brandbergensis , and without setulae. The male terminalia has the same general pattern in the three extant species, but with some differences. The epandrium in A. leukoprosopa is wider than in the remaining extant species. Also, the hypoproct and the postgonite in A. leukoprosopa are much longer than in A. brandbergensis , bent ventrally in this latter species. The connection between the gonocoxal apodemes and the hypandrium is indistinct in A. leukoprosopa , while these structures are visible in A. brandbergensis . Alavesia leukoprosopa seems to be the only known species in the genus, extant or extinct, with a dorsal sensory organ at the basal fourth of the hind tibia.