Pseudeurybata alces Marshall, 2016, new species

Pseudeurybata alces new species

Figs. 1–7

Description. 16–18mm. Head with epicephalon shining but otherwise pollinose. Frontal vitta broad, barely distinguishable from narrow orbital strips or similarly pigmented epicephalon, posterior part of vitta continuing very broad and parallel-sided almost to level of inner vertical setae, then abruptly tapered to postocellar setae. One lower fronto-orbital seta. Arista brown, slightly paler and slightly swollen at base, finely pubescent in basal third. Clypeus shining but very finely and evenly setulose.

Thorax uniformly orange except darker lower margin of propleuron. Anepisternum and anterior part of katepisternum with sparse small dark setae.

Legs black except for orange base of fore coxa, base of mid and hind femora, and long preapical rings on mid and hind femora. Fore tarsomere one and apex of fore tibia with a contrasting ventral fringe of golden-yellow setulae. Wing uniformly lightly infuscated; halter knob black.

Female abdomen with pleuron cream yellow ventrally, brown on dorsal half or slightly more. Oviscape very broad and reddish basally, abruptly tapered and black distally, 3X length of T6. Both spermathecal ducts ringed with striae, paired spermathecae very large, stems dense and tuberculate.

Male abdomen with pleuron 2 forming a broadly expanded pleural sac, cream yellow on ventral half and dark on dorsal half; pleuron 2 dark on anterior margin, pleuron otherwise cream yellow except along dorsal third. Genital fork of sternite 5 greatly enlarged, with inner basal process very long and arm so strongly arched it is bent at a right angle. Distiphallus broad, terminating in a dense phallic bulb half as long as basal part of phallus.

Type material (all Costa Rica). Holotype (♂, MNCR). Estacion Cacao, 1000–1400m, Lado SO Volcan Cacao, P.N. Guanacaste, M. A. Zumbado, 21–29.May.1992, L-N 323300–375700. Paratypes. Alajuela, San Ramon Biol. Res, 900m, May.2000, P. Hanson (6♀, DEBU); Alajuela, San Ramon Biol. Res, 75. Oct.1995, yellow pans, 700m, G. Carballo (1♀, DEBU); La Suiza 24, Pablo Schild (1♀, USNM); Est. Cacao, 1000–1400m, Lado SO Volcan Cacao, P.N. Guanacaste, second parataxonomist course, June 1990 L-N- 323300-375700 (♂, MNCR); Puntarenas, Buen Amigo, San Luis Monteverde, A.C. Arenal, 1000–1350m, May.1994, Z. Fuentes (♀, MNCR); same as previous but Malaise trap, Apr.1995 (♀, MNCR); Puntarenas, Monteverde Biol. Stn, lower trail, 14–18.Aug.2010, S.A. Marshall (1♀, DEBU).

Etymology. The specific name of Pseudeurybata alces refers to the antler-like male genital fork, which resembles a young moose (Alces alces) antler.

Distribution. Costa Rica.

Remarks. Pseudeurybata alces has been observed ovipositing in rotting logs at Monteverde, Costa Rica (Figs. 2–3). All flies seen at that time were female, as are all specimens in the type series with the exception of the male holotype and a single male paratype, both taken at the Cacao Station in Guanacaste National Park. The remarkable genital fork distinguishes males of this species from all other Micropezidae. Females are recognizable by the combination of brown tarsi, orange scutum and orange-banded hind femora.