Bregmosina obunca, Marshall, Stephen A., 2013

Marshall, Stephen A., 2013, Bregmosina, a new Neotropical genus of Limosininae (Diptera: Sphaeroceridae), Zootaxa 3641 (3), pp. 260-270 : 266-268

Bregmosina obunca new species

Figs. 18–22

Description. Size (antennal base to wing tip) 1.9–2.0 mm. Eye height 2.5–2.6X genal height. Lower orbital bristle thin, 0.3–0.4X as long as upper orbital bristle. Tarsomeres 2–5 of fore leg short, slightly flattened and widened; tarsomeres 2, 3 and 5 equal in length, tarsomere 4 shorter. Tarsomeres 1 and 2 of hind leg weakly swollen, second tarsomere as long as tarsomeres 3, 4, and 5 combined. Mid tibia with 3 distal dorsal bristle, including a long anterodorsal, a long dorsal, and a short posterodorsal (length equals tibial width). Wing: Second costal sector 0.6– 0.7 times as long as third; R2+3 evenly bowed, not sinuate.

Female abdomen: Tergite 8 shortened dorsomedially, broad laterally. Cercus as long as middle part of tergite 8, with a long apical bristle. Spermathecae large (diameter greater than length of sternite 7), spherical with a small conical base; ducts thin and sclerotized, longer than spermatheca. Sternite 8 pale anteromedially. Sternite 10 divided posteromedially, forming two posterior lobes.

Male abdomen: Sternite 4 extensively overlapping sternite 5, posteromedial part with two short, rounded lobes. Sternite 5 desclerotized medially, made up mostly of two long posterolateral lobes and their broad bases, lobes as long as rest of sternite and pointed and slightly incurved distally. Posteromedial point of sternite 5 weakly ridged. Ventral part of sternite 6 relatively broad, concave posteromedially. Ring sclerite complete. Cerci separate, elongate-rectangular. Surstylus elongate and sinuate, ending in a conspicuously long, anteroventrally pointed apex. Postgonite "can opener"-shaped, posterior lobe conspicuously longer than broader anterior lobe. Basiphallus with a short, broad epiphallus. Distiphallus narrow, dorsal surface with inconspicuous spiked surface near base.

Type material. Holotype male (INBIO) and 3 paratypes (13, 2Ƥ, DEBU): COSTA RICA. Alajuela. Volcan Tenorio, N slope nr. Bijagua Biological Station, 700 m, pans in treefall, 18.vi.2000, Buck and Marshall. Other paratypes: COSTA RICA. Heredia. Pico Viejo, La Selva Biological Station, 8–15.v.1989, B. Brown and D. Feener, Malaise trap, CC100 (13, DEBU); Puntarenas, R.F. Golfo Dulce, 3 km SW Rincon, 10 m, x–xii.1990, P. Hanson (13, 1Ƥ DEBU); Braulio Carrillo National Park, 10.iv. 1985, 500 m, H. Goulet, L. Masner (1Ƥ, DEBU). GUYANA. Mazaruni-Potaro Distr., Tukelt Creek on E. side Potaro, 300’, rainforest, Malaise, 26–30.ix.1990, B. Hubley, L.D. Coote (1Ƥ, 13, ROM 905019).

Etymology. Bregmosina obunca is named for the hooked surstylus (from the Latin obuncus, bent in or hooked).

Comments. Bregmosina obunca and B. howdeni are obviously closely related but B. obunca is distinct for the long, pointed anteroventral surstylus apex and the bilobed posterior margin of male sternite 4. Both species differ from congeners by their greatly reduced lower orbital bristle and by the strikingly large posterolateral processes of the male fifth sternite. The holotype was collected at the same time and place as B. buck, but these species are extremely different in male and female abdominal characters.

Figures

FIGURES 18 – 22. Bregmosina obunca and B. howdeni. 18, B. obunca female terminalia; 19, B. obunca aedeagus and associated structures left lateral; 20, B. obunca male terminalia ventral; 21, B. obunca epandrium and associated structures left lateral; 22, B. howdeni epandrium and associated structures left lateral. Abbreviations: SP, spermatheca; T 7, T 8, S 5, S 7, S 8, sternites and tergites; P, phallapodeme; PG, postgonite; H, hypandrium; C, cercus; B, basiphallus; D, distiphallus; SU, surstylus.