Syringogaster nigrithorax Marshall & Buck

Marshall, S. A., Buck, M., Skevington, J. H. & Grimaldi, D., 2009, A revision of the family Syringogastridae (Diptera: Diopsoidea), Zootaxa 1996 (1), pp. 1-80: 50-53

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Syringogaster nigrithorax Marshall & Buck

new species

Syringogaster nigrithorax Marshall & Buck   , new species

Figs. 40–42; Map 7

DESCRIPTION: Head brown to reddish brown, anterior part of frons, face and gena yellowish brown. Vertex almost straight, very weakly convex at middle. Frons tomentose, contrasting with shining ocellar triangle; latter bordered on each side by a row of minute inclinate bristles, anterior apex separated from frontal margin by width of first flagellomere. Ocellar bristles absent. Entire pedicel tomentose. Parafacial setulae inconspicuous, scattered around vibrissal angle. Gena and subgena subequal in height, gena with a row of fine brown bristles. Supracervical collar strongly developed, ca. 3X as long as pronotum at middle.

Thorax, except legs, entirely black, tomentose except for the following shining to subshining (dulled by fine, shagreened surface sculpture) areas: prosternum, postpronotum, humeral carina, anterior third of anepisternum, katepisternum except narrow dorsal strip and small band along midventral suture and postmetacoxal bridge. Antepronotum setulose except for a narrow ventral strip. Anterior margin of humeral pit with a prominent carina extending well lateral of pit. First prespiracular process small, narrowly triangular, second prespiracular process broad and blunt, shining dorsally. Subspiracular lamella entirely tomentose. Fore coxa and trochanter ivory, otherwise fore leg yellow to pale brown. Anteroventral margin of distal part of fore femur with row of 10–12 short stout bristles. Mid femur ivory basally, rest of leg pale brown. Mid tarsomeres 1–3 and basal 4/5 of tarsomere 4 with antero- and posterodorsal sawlines. Hind trochanter pale yellow. Hind femur orange-brown with slightly paler base, with a broad, brown, longitudinal stripe from base to apex, and dark anteroventral stripe in distal third just above row of spines. Hind femur evenly convex dorsobasally, concave dorsally on distal third; anteroventral row of 13–14 spine-like bristles extending over distal 3/4–5/6 of femur, posterior row shorter. Hind tibia with apex strongly trilobate, anteroventral lobe longer than in any other species, its length nearly as great as width of basitarsus. Hind tarsomere 1 with anteroventral sawlines, tarsomeres 2–4 with antero- and posteroventral sawlines, those on tarsomere 4 well developed and extending nearly whole length of tarsomere.

Wing dark with clear patches before and after crossvein dm-cu and between crossveins r-m and bm-cu. R 2+3 running almost parallel to costa distally, not distinctly turned up to costa near apex. Cell r 4+5 moderately tapered from apex to level of r-m; r-m less than one third as long as dm-cu. Fork of CuA distal to bm-cu, separated from bm-cu by approximately the length of bm-cu (bm-cu weak); CuA 1 and A 1 +CuA 2 both extending more than half way to wing margin.

Abdomen: Syntergite 1–3 petiolate, tergite 1–2 parallel-sided, tergite 3 twice as wide at apex as base. Syntergite 1–3 densely microsculptured, with well-developed tomentosity except at base of tergite 3. Abdominal tergites medium brown, distal segments slightly paler. Tergite 4 separate from tergite 3.

Male terminalia: Tergite 5 with ventrolateral margins unmodified, ventrolateral margin of tergite 6 with a tapered anteroventral corner; spiracles 5 and 6 in tergite close to lateral margin. Sternite 5 divided into two small, widely separated elongate sclerites, both devoid of setulae; sternite 6 of highly unusual shape: posterior portion transverse with irregular row of setulae, on left side with sclerotized anterior process that is part of a tab-like rounded projection covering area between halves of sternite 5 (including most of right half of latter); tab with small sclerite on right side, similar in shape and position to right half of sternite 5. Synsternite 7+8 with lateral apodeme on left side, ventral part narrow, left spiracle slightly more dorsal than left one. Epandrium wider than long, anteriorly on each side with large but translucent apodeme. Cercus slender and parallel-sided, 4X as long as wide, with numerous long setae. Surstylus contiguous with cercus, relatively short, 3X as long as wide and widest near middle, convex lateral margin with two long and several short setae. Hypandrium with one pair of breaks and one pair of weakenings: a weakening on each side between basal Ushaped portion and base of hypandrial arm (but not between hypandrial bridge and mesal base of each hypandrial arm) and a break near middle of each hypandrial arm posterior to ventral hypandrial lobe. Anterior U-shaped portion moderately robust, with a pair of well-developed but translucent, paramedian anterior apodemes. Hypandrial bridge broad and robust, with narrow, but well-defined, medial interruption. Phallapodeme very robust, connected at apex of basal third to basal portion of hypandrium through translucent phallic guide. Posterior part of hypandrial arm broad, short ventral lobe with broadly truncate apex; edge of lobe densely setose, posterior margin above lobe also setose. Postgonite of somewhat irregular shape, apical portion weakly sclerotized and projecting beyond base of pregonite. Pregonite with longitudinal dorsal, ventral and medial carinae. Basiphallus straight, slender and parallel-sided (in posterior view), its apex expanded dorsoventrally, lacking lateral lobes. Distiphallus slightly bent towards left side. Basal sclerite of distiphallus strongly sclerotized, much longer than wide and slightly bent near middle, with peculiar, straight, slender, ventrally directed process arising just above middle of left side. Apical sclerites of distiphallus relatively small and of various shapes; distal sclerite made up of two small lamellae enclosing acute angle.

TYPE MATERIAL: Holotype ♂ ( USNM): ECUADOR. Dpto. Orellana, near Yasuní Natl. Pk. , Tiputini Biodiversity Station , 0°37’55”S, 76°8’39”W, 220–250 m, 6.ii.1999, Trans. 7, Sta. 5, fogging in terra firme forest, Lot #2064, T GoogleMaps   . Erwin et al. Paratype: Reserva Etnica Waorani, 1 km S Onkone Gare Camp, Transect Ent. , 0°39’25.7”S, 76°27’10.8”W, 216.3 m, 4.x.1996, Trans. 9, Sta. 4, fogging in terra firme forest, T GoogleMaps   . L. Erwin et al., Lot #1744 (1♂, USNM)   .

COMMENTS: Although similar in color to S. subnearctica   , S. nigrithorax   is characterized by a large suite of unique characters including the following: meron, metapleuron (excluding postmetacoxal bridge) and metasternum entirely tomentose (completely or almost completely atomentose in other species); apex of hind tibia with unusually long anteroventral process; male sternite 6 strongly asymmetrical, projecting tab-like above venter of segment 5 (sometimes asymmetrical but never tab-like in other species); ventral hypandrial lobe with broadly truncate apex (rounded in other species); basal sclerite of distiphallus with slender, fingerlike process on left side above middle (absent in other species). This species is known only from canopy fogging samples in primary rain forest.


Smithsonian Institution, National Museum of Natural History


Tavera, Department of Geology and Geophysics