Acrocephalomyia torulosa, Alvim, Edgar & Ale-Rocha, Rosaly, 2016

Alvim, Edgar & Ale-Rocha, Rosaly, 2016, Two new species of Acrocephalomyia Ibáñez-Bernal & Hernández-Ortiz, 2012 from Brazil (Diptera: Ropalomeridae) and a key to known species, Zootaxa 4067 (1), pp. 57-64 : 60-64

Acrocephalomyia torulosa sp. nov.

( Figs. 6–18 )

Diagnosis. Face covered with white pruinescence; ocelli almost imperceptible, but present; wing yellow, darker between Costal vein and vein R4+5; legs light brown except for yellow first tarsomeres, all femora with dark brown stripes anteriorly at apical third and dorsal rounded silvery spot medially; hind coxa of male with thorn-shaped expansion; fore femur with anteroventral with 8 spine-like bristles and ventral surface covered with short yellow setulae on basal half; mid femur with 2 strong and long posterodorsal bristles at apical third, anterior row with 5 spine-like bristles and anteroventral row with 9 spine-like bristles; hind femur with anterior row bearing 2 spinelike bristles, anteroventral row with 5 spine-like bristles and posteroventral row with 4 spine-like bristles; hind tibia arched.

Description. Holotype male. Body: 13 mm; wing: 11 mm ( Fig. 6 ). Head: Frons ( Figs. 7, 8 and 10 ) concave; predominantly brown, laterally with two black stripes converging anteriorly; posteriorly with triangular, densely silvery pruinescent spot extending from occiput to dorsal half of frons on a depressed line that divides frons in half. Ocellar tubercle absent; ocelli almost imperceptible. Ocellar, postocellar and inner vertical bristles absent. Face pale brown covered with white pruinescence ( Fig. 10 ). Antenna brown, scape and pedicel covered with some short black setulae, especially on dorsal surface and distoventral surface of pedicel; first flagellomere dark brown, almost the same size as pedicel. Palpus elongated, with rounded apex and parallel sides, pale brown with yellowish setulae. Gena ( Fig. 9 ) concolor with face, covered with white pruinescence, with some black setulae and long white and yellow setulae on postgena. Thorax: Scutum brown, about two times longer than wide; four longitudinal silvery pruinescent stripes, one dorsocentral pair and one stripe on each side extending from postpronotal lobe to scuto-scutellar suture; two dark brown acrostichal stripes that do not reach posterior margin of scutum, in addition to one presutural and one postsutural dark brown spot on each side between lateral silvery stripe, and dorsocentral dark brown stripe ( Fig. 7 ). Chaetotaxy: 2 notopleural, 1 postsutural supra-alar, 1 postalar, 1 intra-alar, and 1 intrapostalar. Scutellum shaped as an isosceles triangle; covered with short black setulae and sparse silver pruinescence; one apical pair of bristles, inserted very close to each other. Mesopleuron with silvery pruinescent stripe extending to anepisternum; bristles mostly lacking, but anepisternum, anepimeron and katepisternum with weak, scattered setulae, posterior spiracle without bristles. Wings: yellow, darker between Costal vein and vein R4+5 ( Fig. 7 ). Legs: light brown except for yellow first tarsomeres; all femora with dark brown stripes anteriorly at apical third and dorsal rounded silvery spot medially. Fore coxa covered with silvery pruinescence; hind coxa with a large thornshaped lateral expansion ( Fig. 12 ). All femora covered with fine black setulae; fore femur with anteroventral row with 8 spine-like bristles, posteroventral surface lacking spine-like bristles, ventral surface covered with short yellow setulae on basal half; mid femur ventrally covered with short white setulae, with 2 strong and long posterodorsal bristles on apical third, anterior row with 5 spine-like bristles and anteroventral row with 9 spine-like bristles, posteroventral surface lacking spine-like bristles and dorsally without concavity on basal third; hind femur with anterior row bearing 2 spine-like bristles, anteroventral row with 5 spine-like bristles and posteroventral row with 4 spine-like bristles, and with long black bristles ventrally. Fore tibia with long black bristles, anterior surface with short yellow setulae, denser apically; mid tibia slightly arched, sickle-shaped, becoming wider from basal third, posterodorsal row with 9 spine-like bristles, last three spine-like bristles inserted on tubercle, apical third of ventral surface with 2 tubercles without setulae and 3 subapical spine-like bristles, ventral setulae not dense and ventroapical spine-like bristles lacking; hind tibia arched, ventrally with dense, thin and long black bristles, without tuft of ventroapical short yellow setulae. Abdomen: Tergites 1-5 brown in ground color, evenly covered with short, black setulae and sparse pruinescence laterally. Sternum 5 membranous medially, with some setulae laterally ( Fig. 11 ). Terminalia. Cerci long and fused on basal 1/3; distal 2/3 free and with long, slender bristles laterally and apically ( Fig. 13 ). Surstylus smaller than cerci ( Fig. 14 ), base wider than apex and with medial sclerotized projection ( Fig. 16 ), postgonite bilobed and unusually wide ( Figs. 17 and 18 ). Phallus with two projections on ventral surface medially ( Figs. 15, 17 and 18 ). Dorsal process of hypandrial arms (= “epiphallus”, see discussion below) slender, slightly curved, with apical portion hook shaped ( Figs. 15, 17 and 18 ).

Female. Unknown.

Type material. Holotype male ( DZUP) BRAZIL, labelled: Dourados–M[a]T[o] [Grosso] [do] [Sul], Brasil 27-28, xii.1976, J. Lorenzoni col[etor]. DZUP 200449.

Geographical records. Only the type locality, Brazil (Mato Grosso do Sul).

Etymology. From Latin, torus = elevation, protuberance. Refers to big thorn-shaped expansion on hind coxa.

Discussion. This species can be easily distinguished from congeners by the hind coxa with thorn-shaped expansion.

The morphology of the male terminalia of Acrocephalomyia torulosa sp. nov. suggests that in this genus the terminalia fits the pattern of the family, with epandrium curved ventrally, cerci partially fused, surstylus elongate, postgonite bilobed, phallus membranous and dorsal process of hypandrial arms shaped as a spur. In Acrocephalomyia torulosa sp. nov the phallus bears sclerotized spine-like projections medially. Projections in the phallus have been found only in Ropalomera femorata ( Fabricius, 1805) , but are different in shape and in position, which is preapical. Another very distinct character of this species is the exceptionally widened postgonite, width greater than 2/3 the length, usually less than 2/3 the length in Ropalomeridae .

In Ropalomeridae , the hypandrial arms are fused dorsally, above the base of phallus, from which emerges a curved and sclerotized process. Steyskal (1957) called this structure “spinus titillatorious”, a synonym for the epiphallus of Calyptratae according Griffiths (1972). However, Griffithis (1972) argued that this structure could not be called epiphallus since this sclerotized process is confluent with the hypandrial arms, the dorsal extension of hypandrium ( Cumming & Wood 2009), not with the base of the phallus. Nevertheless, despite the observation made by Griffiths (1972). In this paper we called this process as dorsal process of hypandrial arms.

Figures

FIGURES 6 – 10. Acrocephalomyia torulosa sp. nov.: Habitus: 6, lateral view; 7, dorsal view; Head: 8, dorsal view; 9, lateral view; 10, frontal view. Scale = 1 mm.

FIGURES 11 – 12. Acrocephalomyia torulosa sp. nov.: 11, sternum 5; 12, hind coxa with thorn-shaped expansion.

FIGURES 13 – 18. Acrocephalomyia torulosa sp. nov.: Male terminalia: 13 – 14, epandrium, ventral and lateral view; 15 - 18, inner male terminalia, 15, surstylus, dorsal view; 16, lateral view; 17 – 18, inner male terminalia, ventral and posterior view. Scale = 0,5 mm. Abbreviations: cerc, cercus; dor proc: dorsal process; epand, epandrium; gon, gonocoxite; hypd, hypandrium; phal, phallus; phal proj, phallus projection; postg, postgonite; sur, surstylus.