Brahemyia, Amorim, Dalton De Souza, 2007

Amorim, Dalton De Souza, 2007, Two new genera of Swammerdamellini (Diptera, Scatopsidae), with a discussion of the position of the species of Rhexoza, Zootaxa 1640, pp. 41-53 : 48-50

Brahemyia , gen.n.

( Figs 17–22 )

Type –species. Rhexoza lobata Cook (by present designation).

Diagnosis. Two regular whorls of setae on flagellomeres. Antepronotum entirely divided. Length of cell r5 at least six times its width at base. Sternites 1–6 unsclerotized. Pre–tergites 2 and 3 produced. Aedeagal plate present, shape variable, not flattened. Tergite 9 deeply divided by a distal incision, with lateral halves well separated; gonostylus absent, parameres extended laterally; sperm duct coming out from a hole in the aedeagal sclerite.

Etymology. This genus is named after the Danish astronomer Ticho Brahe (1546–1601).

Description. Body length, 1.50–2.67 mm long. Most species rather shining, blackish brown, except for light brownish–yellow tarsi. Flagellum always with 8 flagellomeres, each with two regular crowns of setae. Maxillary palpus long, reniform, with shallow, elongated, poorly defined sensorial pit. Thorax only slightly elongated. Anterior margin of antepronotum completely divided into an anterior and a posterior portion by an oblique line of desesclerotization. Wing hyaline, venation as other Swammerdamellini except for a discrete angle on anterior fourth of M 1 in most species; L/C1 about 3.7, L/C2 about 4.3, L/C1+C2 about 2.0. Pretergites present on both segments 2 and 3. Sternites 5 and 6 not produced. Segment 7 well produced, tergite 7 and sternite 7 both with a line of strong sclerotization along anterior margin; sternite 7 always with a posterior incision. Aedeagal sclerite with an anterior hole through which the efferent duct comes out. Parameres short distally, bare of setae. Tergite 9 with a deep incision, completely dividing it into a pair of lateral, elongated sclerites. Sternite 9 well developed, with elongated arms; epandrium restricted to a pair of short, lateral setose sclerites connected anteriorly. Cerci absent.

Discussion. This new genus presently includes only the type –species, but there is quite a number of Neotropical species to be described. Brahemyia is undoubtedly monophyletic, as indicated by the complete division of the antepronotum, the unsclerotized sternites 5–6, and the shape of the aedeagal plate. Sternite 7 in most species has a wide and deep notch, resulting in a pair of elongated, rectangular posterior arms projected from a short anterior base; tergite 7 is also modified in some species. In all species the aedeagal sclerite has an anterior hole through which the efferent duct comes out. The shape of the aedeagal plate distally varies considerably among the species. In some species the posterior incision of tergite 9 completely divides it into a pair of separate, lateral, elongated sclerites. The sternite 9 is usually well developed, elongated in some species, as seen in other species of the higher Swammerdamellini. Even though the male terminalia of some species of the genus do not differ too strongly from the condition seen in Quateiella and Cooka n.gen., some species have diverged considerably, especially with modifications in the shape of tergite 9. The genus would compose a clade with Quateiella , Abrhexosa , and Cooka , gen.n. and, as commented above, within this clade it would join Cooka , gen.n. in a smaller monophyletic group.

Species included. Neotropical: B. lobata (Cook, 1956) , n.comb.

Figures

FIGURES 17 – 22. Brahemyia lobata (Cook). Male holotype. 17, head. 18, wing. 19, thorax. 20, segment 7. 21, male terminalia, ventral view. 22, same, dorsal view. Arrow indicates the complete division of the antepronotum, an autapomorphy of Brahemyia.