Stilobezzia (Stilobezzia) biscutata, Cazorla & Unlp, 2013

Cazorla, Carla G. & Unlp, 2013, A new species of Stilobezzia (Diptera: Ceratopogonidae) from northern Argentina, Acta Entomologica Musei Nationalis Pragae 53 (1), pp. 323-327 : 324-326

Stilobezzia (Stilobezzia) biscutata sp. nov.

( Figs 1–11 )

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 ). Head ( Fig. 1 ) 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 ) 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 ). Genitalia ( Figs 4–6 ): 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 ). Similar to male, except for the following differences: Head ( Fig. 7 ). 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 ). 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 ) 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 ). Pigmentation as in Fig. 10 . Genitalia ( Fig. 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).

Figures

Figs 1–6. Stilobezzia (S.) biscutata sp. nov., holotype male:1 – head (dorsal view); 2 – wing; 3 – abdomen (laterodorsal view); 4 – genitalia; 5 – detail of genitalia (ventral view); 6 – parameres removed. Scale bars: 0.05 mm.

Figs 7–11. Stilobezzia (S.) biscutata sp. nov., allotype female: 7 – head (dorsal view); 8 – wing; 9 – thorax (lateral view); 10 – abdomen (dorsal view); 11 – genitalia (ventral view). Scale bars: 0.05 mm.