Planinasus nigritarsus, Mathis, Wayne N., Rung, Alessandra & Kotrba, Marion, 2012

Mathis, Wayne N., Rung, Alessandra & Kotrba, Marion, 2012, A revision of the genus Planinasus Cresson (Diptera, Periscelididae), ZooKeys 225, pp. 1-83 : 48-51

12. Planinasus nigritarsus sp. n. Figures 65-69

Description of male.

Moderately small flies, body length 2.10-2.80 mm.

Head: Head ratio 0.56-0.60; frons generally brownish black to black, mostly bare, shiny, except for microtomentose, velvety-appearing, anterolateral angles and overcut, anterior margin, anterolateral area setulose; frons conspicuously wider than long, frontal ratio 0.47-0.50; interfrontal seta shallowly curved, elongate, length subequal to length of lateral vertical seta. Antenna mostly yellowish orange, especially medially and ventrally; pedicel mostly yellowish, especially medially, brown dorsally; basal flagellomere moderately long, length conspicuously greater than height at base, tapered to moderately acute point at apex, both dorsal and ventral margins curved; pedicel with ventral projection short, not extended anteriorly much beyond dorsal margin, bearing long, ventroapical seta (extended slightly beyond apex of basal flagellomere), 1 dorsomedial seta and 1 medial seta; arista bearing 13-14 dorsal rays, 3-4 ventral rays. Face comparatively wide, facial ratio 0.60-0.64; dorsad of transverse carina moderately microtomentose, appearing subshiny, mostly blackish brown, but antennal grooves yellowish and with silvery white microtomentum immediately dorsal of transverse carina; ventrad of transverse carina densely microtomentose, silvery white, sericeous; large facial setae arranged in a single transverse row of about 8 setae, medial pair of setae approximate, ventroclinate, next seta curved dorsally, lateral 2 setae ventroclinate. Clypeus and palpus brownish black; clypeus with some silvery white microtomentum.

Thorax: Mesonotum generally brownish black to black, sparsely microtomentose, subshiny to shiny; postpronotum brown with some yellowish coloration around margin; area from postpronotum and through notopleuron mostly bare, finely microtomentose, dull; pleural areas finely microtomentose, dull, blackish brown; anepisternum mostly bare but with several setulae dorsally and posteriorly, 3-4 setulae along posterior margin longer than others; katepisternum generally setulose, bearing 2 setae toward dorsal margin. Wing without pattern, generally infumate, slightly more so anteriorly, base hyaline. Coxae and trochanters whitish yellow to yellow; femora and tibiae uniformly brownish black; base of femora yellowish; forefemur with a preapical, pale area medially; foretarsus mostly dark, especially dorsally, brownish to blackish, paler ventrally, yellowish; mid- and hindtarsi mostly yellowish, apical 2-3 tarsomeres becoming darker; forefemur bearing 1 seta at apical 1/3 along posteroventral surface.

Abdomen: Uniformly blackish brown, mostly dull to faintly subshiny, moderately invested with microtomentum. Male abdomen: Tergites 1+2-6 well developed, lengths of tergites 3-6 subequal; tergite 7 narrow; sternite 3 only slightly wider than long, posterior margin nearly straight; sternite 4 rectangular with width about 1.5X length; sternite 5 rectangular with width about twice length, becoming slighter wider posteriorly, posterior margin of sclerotized portion nearly straight; sternite 6 apparently absent; sternite 7 narrow, band-like, forming an annulus with tergite 7. Male terminalia (Figs 65-68): Epandrium in lateral view (Fig. 65) broadly rectangular on anterior half, greatest width as wide as high, narrowed dorsally, anterior margin very shallowly emarginate, posterior margin straight, angled posteriorly, forming a pointed, broadly based projection; surstylus length 1/3 length of epandrium, extended from posteroventral margin of epandrium in nearly oblique alignment with it, in lateral view (Fig. 65) relatively short, bilobed, dorsal lobe smaller, length half that of ventral lobe, bearing apical, elongate setulae, ventral lobe as a parallelogram, more robustly developed than dorsal lobe, bearing several shorter setulae; hypandrium in ventral view (Fig. 66) angularly and robustly U-shaped, arms only slightly narrower than anterior margin, anterior margin nearly straight, robustly developed; postgonite in ventral view (Fig. 66) robust, bearing densely setulose lobe, length of lobe more than twice width,, lobe in lateral view (Fig. 68) ovate, apex expanded, bearing more than 20 setulae; phallus in ventral view forming complex, convoluted structure with pre- and postgonites, in lateral view (Fig. 68) with narrow, bar-like processes; phallapodeme in lateral and ventral views (Figs 68, 66) elongate, in ventral view (Fig. 66) parallel sided, bluntly rounded apically, in lateral view slightly curved, especially along dorsal margin, slightly dilated basally, apical 1/3 parallel sided; ejaculatory apodeme in lateral view (Fig. 67) enlarged, longer than phallapodeme, basal half relatively slender, almost parallel-sided, apical 1/3 greatly expanded, fan-like.

Description of female.

As in male except as follows: Head generally narrower, head ratio 0.60-0.62; frontal ratio 0.61-0.64; facial ratio 0.27-0.31.

Type material.

The holotype male is labeled "GUYANA. CEIBA (ca. 40 km S Georgetown)[,] 06°29.9'N, 58°13.1'W [,] 21 April 1995[,] Wayne N. Mathis/USNM ENT 00134161 [plastic bar code label]/HOLOTYPE ♂ Planinasus nigritarsus Mathis & Rung USNM [red]". The holotype is double mounted (minuten in a block of plastic elastomere), is in excellent condition, and is held in trust at the USNM for eventual deposit in Guyana. Nineteen paratypes (13♂, 6♀; USNM) bear the same label data as the holotype. Other paratypes are as follows: Same locality as the holotype but with dates from 13 Apr-28 Aug 1994, 1997 (17♂, 5♀; USNM).

Type locality.

Guyana. Conservation of Ecological Interactions and Biotic Associations (CEIBA; ca. 40 km S Georgetown; 06°29.9'N, 58°13.1'W).

Other specimens examined.

BOLIVIA. La Paz: Mapiri (5 km W; Arroyo Tuhiri; 15°17.8'S, 68°15.6'W; 750 m), 16-19 Mar 2001, S. D. Gaimari, W. N. Mathis (3♂; USNM).

BRAZIL. Amapá: Serra do Navio (0°52'N, 52°01.5'W; Malaise trap), 15-17 May 1989, N. Bittencourt (1♀; INPA). Amazonas: Manaus, Universidade Federal do Amazonas (03°05.9'S, 59°58.2'W; 50 m), 7 May 2010, D. and W. N. Mathis (1♂; USNM); Reserva da Campina, Rio Abacaxis (04°35.8'S, 58°13.2'W), 30-31 May 2008, J. A. Rafael (1♀; INPA); Reserva Florestal Adolpho Ducke (02°55.8'S, 59°58.5'W; 40 m), 5 May 2010, D. and W. N. Mathis (1♂; USNM); Reserva Florestal Adolpho Ducke, baixio trilha leste-oeste (02°55.8'S, 59°58.5'W; suspension trap), Mar 2004, G. Freitas, J. Vidal (1♂, 1♀; INPA); Reserva Florestal Adolpho Ducke, Platô, trilha leste-oeste (02°55.8'S, 59°58.5'W; suspension trap), 14 Feb-6 Mar 2007, G. Freitas (1♀; INPA); Reserva Florestal Adolpho Ducke, Igarapé Barro Branco (02°58.1'S, 60°0.3'W; Malaise trap, suspension trap at 25 m), Feb 2004, A. Henriques (2♀; INPA); Reserva Florestal Adolpho Ducke, Igarapé Tinga (02°55.8'S, 59°58.5'W; Malaise trap, suspension trap at 25 m), Mar-23 Sep 2004, A. Henriques (2♀; INPA); Sítio Vida Tropical (02°51.9'S, 59°55.9'W; 60 m), 5 May 2010, D. and W. N. Mathis (1♂; USNM); Urini (03°03'S, 65°41.7'W), 22 Jul-3 Aug 1995, N. Aguiar, P. Bűhmhein (1♀; INPA). Maranhão: São Pedro da Água Branca, Fazenda Santa Rosa (05°07.8'S, 48°15.2'W), 6 Dec 2001, F. L. Oliveira, J. A. Rafael, J. Vidal (1♀; INPA). Pará: Óbidos, Fazenda Pajurá (01°37.4'S, 55°23.2'W), 1 Sep 2001, J. A. Rafael, J. Vidal (1♂; INPA); Rio Zingu Camp (03°39'S, 52°22'W; ca. 60 km S Altamira), 2-8 Oct 1986, O. S. Flint, P. Spangler (2♀; USNM); Apr 1930, N. C. Davis (1♂; USNM); Tucurui, Rio Tocantins (03°45.1'S, 49°40.5'W), 9-11 Jun 1984, (1♀; INPA).

PERU. Madre de Dios: Río Manu, Pakitza (11°56.6'S, 71°16.9'W; 250 m), 9-23 Sep 1988, A. Freidberg, W. N. Mathis (6♂, 2♀; USNM).

Distribution

(Fig. 69). Neotropical: Bolivia (La Paz), Brazil ( Amapá, Amazonas, Maranhão, Pará), Guyana, and Peru (Madre de Dios).

Etymology.

The specific epithet, nigritarsus, is of Latin derivation and alludes to the dark tarsomeres of the foreleg.

Remarks.

See “Remarks” under Planinasus argentifacies for a discussion on distinguishing characters as well as similar morphological characters.

The nigrifacies group

Included species. Planinasus atriclypeus sp. n., Planinasus atrifrons sp. n., Planinasus flavicoxalis sp. n., Planinasus mcalpineorum sp. n., and Planinasus nigrifacies sp. n.

Diagnosis. This species group is distinguished by the following combination of characters: Head: Interfrontal seta short, about half length of lateral vertical seta. Antennal coloration variable; pedicel with short ventral projection; basal flagellomere short, about as high as long. Large facial setae arranged in 2-3 transverse rows; face of males and females similar in shape and color. Thorax: Anepisternum with 1 large seta along posterior margin. Wing hyaline to faintly infumate. Forefemur lacking su bapical, irregular, pale-colored annulus, bearing 2 large seta at apical 1/3 along posteroventral surface. Abdomen: Surstylus in nearly oblique alignment with epandrium, generally bearing a posterior process, or lobe, with a setula; postgonite generally with a digitiform lobe bearing a few setulae apically; phallus mostly membranous; ejaculatory apodeme generally greatly reduced.

Discussion. This species group may not be monophyletic, being based primarily on plesiomorphic characters, and comprises the “remainders” species that could not be conveniently placed in other groups. Species of this group share, with those of the shannoni group, and with Planinasus obscuripennis the greatly reduced phallapodeme (conspicuous only in Planinasus nigrifacies in this group) and the small number of setulae on the lobe of the postgonite (less than 6). Furthermore, in the shannoni and nigrifacies groups, the phallus is only partially sclerotized, contrasting with the heavily sclerotized phallus typical of species of the nigritarsus and ambiguus groups.