Stilobezzia ( Stilobezzia ) biscutata, Cazorla & Unlp, 2013

Stilobezzia ( Stilobezzia) biscutata View in CoL sp. nov.

( Figs 1–11 View Figs 1–6 View Figs 7–11 )

Type material. HOLOTYPE (J), ALLOTYPE ( ♀): ARGENTINA: FORMOSA: Estancia La Marcela , 5 km E El Colorado, v.2005, F. Brusa, at light ( MLP) . PARATYPES: (3 JJ 2♀♀): same data as holotype, 1J 2♀♀ ( MLP). ARGENTINA: CORRIENTES: Colonia Pellegrini, 21/ 27.ix.2002, 1 J, M. C. Coscarón, Malaise trap ( MLP). CHACO: 26°48′32.38″S 59°36′26.13″E, next to Río Negro, 30.x.2010, 1 J, M. C. Melo, at light ( MLP).

Diagnosis. A small, yellowish species of Stilobezzia s. str. with the following combination of characters: proximal half portion of the scutum blackish brown except the pale yellowish humeral pits and a mesal anterodorsal narrow line, and the distal half portion bright yellowish; males have stout, S-shaped parameres and gonocoxites with a mesoventral lobe; females have the tarsomere 5 of all legs with two basal, stout, divergent spines and the abdomen is pale brown except dark brown segments 3, 4 and 7, segment 3 has a laterodistal pale spot and segments 4–5 are slightly darker dorsally.

Description. Male ( Figs 1–6 View Figs 1–6 ). Head ( Fig. 1 View Figs 1–6 ) brown. Antenna with flagellomeres brown, flagellomeres 1–5, 11–13 darker; plume brown, poorly developed; antennal ratio 0.90–0.95 (0.92, n = 2). Palpus brown except darker fifth segment; third segment slender with subapical sensory pit; palpal ratio 4.20–4.40 (4.35, n = 4).

Thorax. Proximal half portion of scutum blackish brown, humeral pits, mesal anterodorsal narrow line pale yellowish, distal half portion bright yellowish; scutellum pale yellowish with 4 stout setae; postscutellum dark brown; proximal half portion of pleura brown, distal portion pale yellowish. Legs brown; coxa pale brown; hind femur, tibia slightly darker, distal apex of tibia dark brown; tarsomere 1 of hind leg with three ventral rows of spines, tarsomere 1 of mid leg with basal spine; hind tibial comb with 9 spines; prothoracic tarsal ratio 2.00–2.30 (2.14, n = 4); mesothoracic tarsal ratio 2.38–2.75 (2.53, n = 4); metathoracic tarsal ratio 2.08–2.36 (2.24, n = 4). Wing ( Fig. 2 View Figs 1–6 ) length 1.51–1.60 (1.55, n = 4) mm; width 0.51–0.57 (0.53, n = 2) mm; membrane slightly infuscated with diffuse brown spot on r-m crossvein; second radial cell 4.00–5.00 (5.65, n = 3) times longer than first; cubital fork distal of level of base of r-m crossvein. Halter pale.

Abdomen. Pale brown except dark brown segments 3, 6, 7 with dorsomedial pale spot, segments 4–5 slightly darker dorsally ( Fig. 3 View Figs 1–6 ). Genitalia ( Figs 4–6 View Figs 1–6 ): tergite 9 reaching apex of gonocoxite, distal margin rounded with mesal notch; sternite 9 not clearly distinguished, flattened; cerci stout. Gonocoxite stout, 2.00 times as long as greatest breadth; mesoventral lobe reaching mesal pointed tubercle; gonostylus slender, as long as gonocoxite. Parameres separate, subparallel, S-shaped; distal 1/3 slender, hook shaped; basal apodemes stout, sclerotized, bilobate. Aedeagus represented by 2 slender, subparallel sclerites, each slightly sclerotized with proximal portion curved, distal portion pointed.

Female ( Figs 7–11 View Figs 7–11 ). Similar to male, except for the following differences: Head ( Fig. 7 View Figs 7–11 ). Antenna with flagellomeres brown; antennal ratio 1.29–1.43 (1.37, n = 3). Palpal ratio 3.50–4.40 (3.97, n = 3). Mandible with 8 teeth.

Thorax ( Fig. 9 View Figs 7–11 ). Tarsomere 5 of all legs with two basal, stout, divergent spines; prothoracic tarsal ratio 2.30–2.50 (2.40, n = 3); mesothoracic TR 2.54–2.80 (2.68, n = 3); metathoracic TR 2.27–2.44 (2.36, n = 3); claws as long as tarsomere 5, with conspicuous basal tooth. Wing ( Fig. 8 View Figs 7–11 ) length 1.49–1.77 (1.66, n = 3) mm; width 0.58–0.67 (0.64, n = 3) mm; second radial cell 5.33–6.60 (5.91, n = 3) times longer than first.

Abdomen. Pale brown except dark brown segments 3, 4, 7, segment 3 with laterodistal pale spot, segments 4–5 slightly darker dorsally ( Fig. 10 View Figs 7–11 ). Pigmentation as in Fig. 10 View Figs 7–11 . Genitalia ( Fig. 11 View Figs 7–11 ): sternite 8 pale, not clearly distinguishable, apparently rounded with posteromedi- an excavation U-shaped; sternite 10 pale, with 4 pairs of setae; cercus rounded, short. One globose spermatheca without neck, measuring 8.2 by 7.3 μm.

Differential diagnosis. Stilobezzia ( S.) biscutata sp. nov. strongly resembles S. ( S.) transversa Lane & Forattini, 1958 in the pigmentation pattern of the scutum and legs, but the latter species can be distinguished by uniformly brown abdomen, elongated parameres and wing membrane without a dark spot.

Etymology. The species name biscutata (-us, -um; = ‘having two scuta’) refers to the contrasting pigmentation of the scutum of this species, having the proximal half portion dark brown and the distal portion bright yellowish.

Distribution. Argentina ( Formosa, Chaco and Corrientes provinces) (this paper).