Acrocephalomyia Ibáñez-Bernal & Hernández-Ortiz, 2012

Ibáñez-Bernal, Sergio & Hernández-Ortiz, Vicente, 2012, The new genus Acrocephalomyia, and a new species of Ropalomera from Costa Rica, with additional records for other Mesoamerican species (Diptera: Ropalomeridae), Zootaxa 3478, pp. 553-569 : 554

Acrocephalomyia Ibáñez-Bernal & Hernández-Ortiz , gen. nov.

Type –species. Acrocephalomyia zumbadoi Ibáñez-Bernal and Hernández-Ortiz sp. nov.

Etymology. From Greek ἄκρον, akron = top, peak, at the end; κεφαλή, cephalon = head; μύγα, myia= fly; referring to the anteriorly angled head that resembles a peak in lateral view. Gender feminine.

Description. Flies of medium size with body length about 14 mm; frons flat, extending forward and forming an acute angle with face in front of anterior margin of eyes; face flat, without tubercle or cavities; arista bare, orbital bristles very small, nearly obsolete; ocelli absent; frons devoid of setae excluding outer divergent verticals. Scutum and scutellum evenly covered with short setulae; postpronotum without bristle; scutum with two notopleural, one postsutural supra-alar, one postalar, one intra–alar and one intra-postalar bristles. Scutellum subtriangular with length exceeding basal width, without marginal or discal bristles excluding short divergent apical pair with bases closely approximated. Femora not strongly enlarged, tibiae not strongly flattened. Wing slender, with length approximately 3 times maximum width, evenly fumose. Male and female terminalia were not dissected so as not to affect the type specimens.

Comments. Genus Acrocephalomyia is easily distinguishable from all other genera of Ropalomeridae by the angular anterior projection of the head, absence of ocelli, flat face, antennal arista bare, elongated scutum and elongate, dorsally flattened, subtriangular scutellum, with only one pair of closely spaced apical bristles. The absence of postpronotal bristles in Acrocephalomyia is shared with Mexicoa Steyskal , Apophorhynchus Williston , and Dactylissa Fischer. Dactylissa differs by having a micropubescent arista, first flagellomere with length twice width, the ocellar, postocellar, inner and outer vertical bristles present. Mexicoa and Apophorynchus also differ by the plumose arista and inner and outer verticals bristles present.

The discovery of Acrocephalomyia zumbadoi should modify slightly the diagnosis of the family Ropalomeridae as stated by Steyskal (1987), as the ocelli and the ocellar, postocellar and inner vertical bristles are secondary lost in Acrocephalomyia .