Robustagramma biangulatum 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 : 68-71

Robustagramma biangulatum Cui and Marshall , new species

( Figs. 185–191 , 371 )

Body length 1.5–2.1 mm. General color reddish to dark brown, heavily pollinose but rarely with conspicuous patterns.

Head: Face, gena, antenna and lower frons reddish; head otherwise dark brown. Interfrontal bristles in three pairs. Two orbital bristles, anterior bristle half as long as posterior. Uppermost orbital setula present between orbital bristles; lower orbital setulae small. Postvertical bristles slightly smaller than inner occipitals, parallel or slightly convergent; postocellar bristles weak. Eye height ca. 2.3–2.4 times genal height. Arista dorsolateral, preapical, short, subequal to or slightly longer than head height. Aristal hairs very long, ca. 3 times basal width of arista. Palpus relatively thin, maximum palpal width ca 0.16–0.20 length of palpus. Palpus with two preapical bristles and 4 or 5 ventral setulae. Preapical palpal bristles nearly twice as long as maximum palpal width.

Thorax: Prosternum narrow, bare. Dorsocentral bristles in 2 postsutural pairs, anterior pair short, similar in length to middle prescutellar acrostichal bristle. Acrostichal setulae in 6–8 rows between anterior dorsocentral bristles; one pair of setulae between prescutellar acrostichal and dorsocentral bristles. Apical scutellar bristle ca. 1.7 times length of scutellum. Posterodorsal katepisternal bristle strong, ca. 2/3 as long as distance between bristle base and wing base; anterodorsal katepisternal bristle small, shorter than half of posterodorsal. Halter knob brown; stem pale yellow. Wing half as broad as long, lightly pigmented, with an inconspicuous brownish portion in front of R 2+3. Length of second costal sector ca. 0.43–0.46X length of third. First costal sector indistinctly thicker than second costal sector in anterior view. R 2+3 straight on basal 2/3, and indistinctly curved forward in distal third. R 4+5; costa ending together before wing apex. Discal cell rounded without appendices. Tarsi and fore tibiae yellow. Mid tibia with a single posterodorsal proximal bristle, an anterodorsal bristle near middle, and an anterodorsal, dorsal and posterodorsal distally. Middle anterodorsal and dorsal bristle small. Mid femur with 2 anterior preapical bristes and a posterodorsal apical bristle. Mid tibia of male with an apicoventral and several short ventral bristles on distal half; mid femur of male with 2 rows of 10–14 ventral proximal bristles.

Male abdomen: Syntergite1+2 with a very small anteromedial area, otherwise all abdominal tergites uniformly dark and similar in length. Sternite 5 ca. 1.5 times as long as sternite 4, with a finely setulose posteromedial margin and a central bare area flanked by stout bristles. Dorsomedial length of epandrium ca. 0.7X length of sternite 8. Surstylus reddish yellow, entirely setose, and subtriangular in shape. Cercus narrow, longer than surstylus. Ejaculatory apodeme large, half as long as aedeagal apodeme.

Female abdomen: Tergites 1–7 uniformly pigmented and entire. Cercus short, setose. Sternite 7 longer than sternite 6, rounded posteromedially; sternite 8 reduced to 2 small sclerites. Sternite 10 pale, transverse, setulose. Spermathecae peanut­shaped, with distal portion larger than basal portion; single spermatheca with a relatively short duct, ca. 1.5 times as long as spermatheca; paired spermathecae with relatively long ducts, nearly 3 times as long as spermatheca.

Holotype (♂, DEBU) and paratypes (30 ♂, 17 ♀, DEBU): MEXICO: Campeche. 87 mi E

Escarcega, 800ft., 8–14.viii.1971, tropical semi­evergreen, human dung, A. Newton.

Other paratypes: Same data as holotype, but 500ft (11 ♂, 7 ♀, DEBU) . BELIZE: San Ignacio. Maya Mountain Lodge , sweep, 6.i.1991 (2 ♂, DEBU) ; dung trap, 7–8.i.1991 (6 ♂, 7 ♀, DEBU) ; 19.i.1991, malaise forest edge (1 ♂, DEBU) , sweep trail (2 ♂, 6 ♀, DEBU) , S. A. Marshall. Caves , forest, dung, 23–29.viii.1972, S. & J. Peck (4 ♂, 3 ♀, DEBU) . Forest , dung, 6–12.viii.1972, S. & J. Peck (1 ♂, DEBU) . COSTA RICA: Cartago. Turrialba , CATIE, 600m, 26.ii.1980 (71 ♂, 74 ♀, DEBU) , 28.ii.1980 (8 ♂, 24 ♀, INBC) ; Florence Forest , cup traps, 28.ii.1980 (2 ♂, 3 ♀, DEBU) , H. & A. Howden. Florence Forest, dung trap, 28.ii.1980, H. Howden (10 ♂, 5 ♀, DEBU) . Heredia. La Selva Biol. Stn. , 10 24 N, 84 00 W, 15m, lowland, rainforest, screen sweep, 15–17.ii.1988, B. Hubley and D. C. Darling (3 ♂, DEBU) . La Selva , 50–100m, carrion trap, 18.ii.1980, H. F. Howden (1 ♂, 1 ♀, DEBU) . Pt . Viejo, La Selva Verde, FIT and dung traps, 3.iii.1991, S. Peck (18 ♂, 13 ♀, DEBU) . 10 km W Pt. Viejo, La Selva Verde , 2–4.iii1991, H. & A. Howden (12 ♂, 14 ♀, DEBU) . 10 km N Pt. Viejo, La Selva Verde , FIT, 3.iii.1991, H. & A. Howden (7 ♂, 11 ♀, DEBU) . La Selva, around dung ball rolled by Canthon moniliatus , 2.ii.1990, Nancy Greig (5 ♂, 2 ♀, DEBU) . Estrella Valley, Pandora , FIT, 16.iii.1984, G. V. Manley & H. F. Howden (1 ♂, 1 ♀, DEBU) . Estrella Valley, Pandora , 20.ii.1984, FIT (1 ♂, 6 ♀, DEBU) , carrion trap (8 ♂, 1 ♀, DEBU) , H. Howden. Guanacaste, Maritza Fld Stn. , malaise trap, 3– 9.ii.1996, J. Noyes (2 ♂, 3 ♀, DEBU) ; Maritza , 15–17.ii.1996, pan/dung, S. A, Marshall (2 ♂, 6 ♀, DEBU) ; Est. Maritza, 600m, Lado oeste del Volcán Orosi , viii.1990 (1 ♂, INBC) ; Est. Pitilla , 700m, 9 km S Sta. Cecilia, v.1990 (1 ♂, INBC) . Puntarenas. Monteverde, San Luis , 1000–1350m, malaise trap, i.1993, Z. Fuentes (1 ♂, DEBU) . Alajuela. San Mateo, Higuito , Pablo Schild (1 ♂, USNM) . GUATEMALA: Peten, Tikal , dung trap, 28– 30.vii.1978, Helava & Kukal (4 ♂, 1 ♀, DEBU) . HONDURAS: L. de Yajoa , 2600ft, dung trap, 1–2.vi.1994, H. & A. Howden (16 ♂, 12 ♀, DEBU) ; Zamorano , 5 km S, dung trap, 22.v.1994, H. & A. Howden (1 ♂, 1 ♀, DEBU) . MEXICO: Campeche. Escarcega , 6 km W El Tormento, 110m, evergreen tropical forest, 12–23.vii.1983, S. & J. Peck (2 ♂, 4 ♀, DEBU) . Veracruz. 8 mi NNW Sontecomapan , rainforest, dung (5 ♂, 4 ♀, DEBU) , human dung (1 ♂, DEBU) , vii–viii.(1971), A. Newton; 10 mi SW Teocelo, 4400ft, Oak , wet human dung, 11–16.vii.1971, A. Newton (2 ♂, 2 ♀, DEBU) ; 33 km NE Catemaca , 160m, Los Tuxtlas Biol. Stn., ridge rainforest FIT(2 ♂, 4 ♀, DEBU) , ravine rainforest FIT(1 ♂, DEBU) , 1.vii–1.viii.1983, S. Peck; Quintana Roo, Kohunlich , 68 km W Chetumal, 160m, tropical seasonal forest, FIT, 14–17.vii.1982, S. & J. Peck (2 ♂, 4 ♀, DEBU) ; 7 km E Huatusco , 1250m, cloud foresrt, FIT, 22.vi–2.viii.1983, S. & J. Peck (1 ♀, DEBU) ; 6 mi NE Catemaco , 1500ft, rainforest, human dung, 30.vii–8.viii.1970, A. Newton (1 ♀, DEBU) . Chiapas. Palenque , 80m, secondary evergreen forest, FIT, 2–23.vii.1983, S. & J. Peck (3 ♂, 3 ♀, DEBU) ; 4 mi S Palenque , rainforest, human dung, 600ft (4 ♂, 2 ♀, DEBU) , 700ft (10 ♂, 8 ♀, DEBU) , 7–15.viii.1971, A. Newton; Bonampok Road, 100 km SE Palenque , 230m, rainforest, FIT, 8–24.vii.1983, S. & J. Peck (1 ♀, DEBU) ; 11 mi NW Ocozocoautla , 3400ft, oak evergreen forest, human dung, 19–25.viii.1971, A. Newton (4 ♂, 4 ♀, DEBU) ; 16 km NW Ocozocoautla, Laguna Belgica , 970m, FIT, 13.vi.1990, H. & A. Howden & B. Gill (2 ♂, 1 ♀, DEBU) ; 5 mi S Bochil , 5000ft, oak, human dung, 18–24.viii.1971, A. Newton (1 ♂, DEBU) ; 20 mi N Bochil , 5600ft, pine, oak, human dung, 16–24.viii.1971, A Newton (1 ♂, DEBU) . Yucatán. 9 mi SE Santa Rosa , 100ft, km 137, tropical sub­decidous forest, human dung, 1/ 4.viii.1971, A. Newton (25 ♂, 8 ♀, DEBU) . Tabasco. 46 mi SE Villahermosa , km 74, 150ft, secondary evergreen rainforest, human dung, 8–15.viii.1971, A. Newton (5 ♂, 3 ♀, DEBU) . PANAMA: Chiriquí. 1360m, Lagunas , 5 km SW Hato del Volcán, dung, 22–27.v.1977 (1 ♂, DEBU) , 22–27.v.1977 (1 ♀, DEBU) , S. Peck.

Etymology: The specific epithet refers to the biangular surstylus.

Comments: The observation that this species sometimes follows dung­rolling scarab beetles (see record by Nancy Greig above) suggests that it might be at least facultatively kleptoparasitic in the dung stores of scarabaeines. See also comments under R. obscuratum .

Figures

FIGURES 185–191. Robustagramma biangulatum sp. nov.: 185, posterior view of male terminalia; 186, lateral view of male terminalia; 187, lateral view of male internal genitalia; 188, male sternite 5; 189, dorsal view of female terminalia; 190, ventral view of female terminalia; 191, spermathecae.

FIGURES 371–378. Robustagramma spp. wings (not to scale): 371, R. biangulatum sp. nov.; 372, R.triangulatum sp. nov.; 373, R. brevicauda sp. nov.; 374, R. cultriforme sp. nov.; 375, R. flavistylum sp. nov.; 376, R. disjunctum sp. nov.; 377, R. acutistylum sp. nov.; 378, R. mirabile sp. nov.