Robustagramma obscuratum Cui and Marshall, 2005

Marshall, Stephen A. & Cui, Yongsheng, 2005, Systematics of Robustagramma, a new genus of New World Sphaeroceridae (Diptera), Zootaxa 1026 (1), pp. 1-122 : 39-42

Robustagramma obscuratum Cui and Marshall , new species

( Figs. 74–80 )

As described for Robustagramma binitidum except as follows.

Body length 1.0– 1.6 mm. Interfrontal bristles in 3 (rarely in 2) pairs. Postvertical bristles convergent, ca. 3/5 as long as inner occipital. Postocellar bristles absent. Eye height ca. 2.8–3.6 times genal height.

Dorsocentral bristles in 2 postsutural pairs, anterior dorsocentral bristles slightly shorter than prescutellar acrostichal bristles. Acrostichal setulae in 6–8 irregular rows between anterior dorsocentral bristles. Posterodorsal katepisternal bristle over half as long as distance between bristle base and wing base; anterodorsal katepisternal bristle small, slightly longer than half of posterodorsal. Wing with length ratio of second to third costal sector ca. 0.48–0.58. Mid femur of male with 4–6 ventral proximal bristles.

Male terminalia: Sternite 5 ca. 1.5 times as long as sternite 4, obscure (without shining patches), with many club­like scales on posteromedial margin, a distinct borderline between dark anterior and pale posteromedial area, and a central patch of short, stout bristles. Dorsomedial length of ependrium ca. 0.3X length of sternite 8. Surstylus setose except for almost bare anteroventral lobe. Postgonite pointed apically. Ejaculatory apodeme small.

Female terminalia: Tergite10 with two small bristles and a posteromedial patch of small setulae. Cerci short, setose. Sternite 7 longer than sternite 6, rounded posteriorly. Sternite 8 absent. Sternite10 short, setulose. Spermathecae with distal portions shorter than basal portions. Paired spermathecae with ducts ca. 3 times as long as spermathecae.

Holotype (♂, DEBU) and paratypes (13 ♂, 11 ♀, DEBU): BELIZE: San Ignacio , Maya Mountain Lodge , dung trap, 7–8.i.1991, S.A. Marshall.

Other paratypes: BELIZE: San Ignacio, Maya Mountain lodge, sweep, second growth forest, 2.i.1991 (2 ♀, DEBU) ; malaise, 7.i.1991 (1 ♂, DEBU) ; sweep trail (2 ♂, DEBU) , malaise forest edge (1 ♂, DEBU) , 19.i.1991, S.A. Marshall. Mountain Pine Ridge, Hidden Valley Inst. , 2500ft., grass­pine, dung traps, 10–15.i.1991, S.A. Marshall (1 ♀, DEBU) . COLUMBIA: Valle, RF Bosque de Yotoco , dung of “ Alovata seniculos”, 16.xi.1997, C.A. Medina (1 ♂, 2 ♀, DEBU) . COSTA RICA: Alajuela, Volcán Tenorio, N slope nr. Bijagua Biol. Stn. , 700m, sweep over Atta mound, 18.vi.2000, S. A. Marshall (1 ♂, 2 ♀, DEBU) . Estrella valley, Pandora , 20.ii.1984, carrion trap, H. Howden (2 ♂, DEBU) . Guanacaste. Guanacaste Cons. Area, Rincon de la Vieja, Las Pailas , 1400m, Clusea rosea forest litter, 18.ii.1996, R. Anderson (1 ♀, DEBU) . Heredia, La Selva near Puerto Viejo , around dung ball rolled by Canthon monillatus , 2.ii.1990, N. Greig (1 ♂, DEBU) . ECUA­ DOR: Pichincha. Río Palenque Stn , 25.ii.1979, dung, S.A. Marshall (1 ♂, DEBU) . Esmeraldas. 11 km SE San Lorenzo, La Chiqita, 5m, dung trap, 10–11.vi.1975 (3 ♀, DEBU) ; carrion, 9–10.vi.1975 (1 ♀, DEBU) , S. Peck. GUATEMALA: Peten, Tikal , dung trap, 28– 30.vii.1978, Helava & Kukal (1 ♀, DEBU) . GUYANA: Mazaruni­Potaro Dist., Tukelt Falls , Potaro R. 300', primary rainforest, human dung trap, 27–29.ix.1990, B. Hubley (2 ♀, DEBU) . MEXICO: Veracruz, 8 mi NNW Sontecomapan , rainforest, human dung, vii– viii.1971, A. Newton (3 ♂, 2 ♀, DEBU) . PANAMA: BCI, Barro Colorado , excremento, 10.iii.1996, N. Eberhyid (3 ♂, 3 ♀, DEBU) . Canal Zone, Barro Colorado Island , malaise trap, vii.1967, W. W. Wirth (2 ♂, 2 ♀, USNM) . Canal Zone, Gamboa, Pipeline Rd. , vii.1967, malaise trap, W.W. Wirth (3 ♀, USNM) . Canal Zone, Isla de Barro Colorado , siguiendo una bola de excremento de Canthon moniliatus , 10.vi.1996, C. A. Medina (1 ♂, 6 ♀, DEBU) . PERU: Madre de Dios Prov., Manu Natl. Pk, Cocha Cashu Biol. Sta. , 380m, mal. trap, 23–30.viii.1986, D.C. Darling (1 ♂, DEBU) . VENEZUELA: Bolívar, 10 km S El. Dorado , 200m, 17.vii–7.viii.1986, B. Gill (57 ♂, 54 ♀, DEBU) . Bolívar, km 40 Sta. Elena­ Icabaru Rd. , 100m, 4–6.viii.1986, B. Gill (2 ♂, DEBU) . Bolívar, 20 km S El Dorado , 220m, 20–23.vii.1986 B.Gill (5 ♂, 2 ♀, DEBU) . Bolívar, 33 km S El Dorado , 220m, 2–7.viii.1986, B. Gill (22 ♂, 14 ♀, DEBU) . Bolívar, 22 km S El Dorado , lowland rainforest, FIT, 25.vi–12.vii.1987, S.& J. Peck (63 ♂, 37 ♀, DEBU) . Aragua, Henri Pittier Natl. Pk., Rancho Grande Biol. Stn. , v. 1998, Ashe, Brooks & Hanley (2 ♂, DEBU) .

Etymology: The specific epithet refers to the lack of shining patches on the male sternite 5.

Comments: The observation that this species sometimes follows dung­rolling scarab beetles (see records by C.A. Medina above) suggests that it might be at least facultatively kleptoparasitic in the dung stores of scarabaeines. Obligate keptoparasitic sphaerocerids occur amongst southern Nearctic species in the genera Ceroptera and Norbommia, but kleptoparasitism has not yet been documented in neotropical sphaerocerids. Other Robustagramma species (see notes under R. biangulatum ) have been collected on dung being rolled by scarab beetles.

Figures

FIGURES 74–80. Robustagramma obscuratum sp. nov.: 74, posterior view of male terminalia; 75, lateral view of male terminalia; 76, lateral view of male internal genitalia; 77, male sternite 5; 78, dorsal view of female terminalia; 79, ventral view of female terminalia; 80, spermathecae.