Brachypogon (Isohelea) borkenti, Spinelli, Gustavo R. & Cazorla, Carla G., 2004

Spinelli, Gustavo R. & Cazorla, Carla G., 2004, A new species of Brachypogon (Isohelea) from arid zones of Argentina (Diptera: Ceratopogonidae), Zootaxa 570, pp. 1-6 : 3-5

Brachypogon (Isohelea) borkenti n. sp.

( Figs. 1–6 )

Diagnosis

A medium­size species of Brachypogon (Isohelea) distinguished by the following combination of characters: scape of antenna with three setae; one katepisternal seta; wing membrane infuscated, anterior margin with significant dip, vein M2 obsolete, veins M1, CuA1, CuA2 not abutting wing margin; two subequal­sized ovoid spermathecae; tergite 9 of male quadrate; posterior projection heptagonal with heavily sclerotized margins; gonocoxite without mesobasal lobe; parameres separated, each half represented by two heavily sclerotized, narrowly pointed and recurved sclerites.

Description of female

Head. Dark brown. Ommatidia with interfacetal setae, narrowly abutting medially. Scape of antenna with three setae; flagellum ( Fig. 1 ) uniformly dark brown; flagellomere 1 with three apical sensilla coeloconica; antennal ratio 1.20 (1.15–1.25, n=2). Clypeus with two dorsolateral setae, two ventrolateral ones. Maxillary palpus ( Fig. 2 ) dark brown; segment 3 with apical, round, shallow sensory pit; segment 4 with two large setae; palpal ratio 2.76 (2.75–2.77, n=2). Proboscis short, length 0.10 (n=2) mm. Mandible with nine stout teeth and 3–4 smaller more basal teeth.

Thorax. Uniformly dark brown; 5 prealar setae; one katepisternal seta. Legs dark brown, tarsi slightly paler; hindtibial spur bifid, hindtibial comb with six spines; hind tarsal ratio 2.12 (2.00–2.25, n=2); tarsomere 1 of hind leg with dense ventral palisade setae; tarsomeres 4 cordiform; tarsomeres 5 with moderately large unequal claws with long basal inner tooth; lengths of claws in proportion of 22:16 on all legs. Wing ( Fig. 3 ) membrane infuscated; anterior margin with a significant dip; stigma, veins brown; r­m crossvein oblique; vein M2 obsolete; veins M1, CuA1, CuA2 not abutting wing margin; macrotrichiae present in margin of cells r3, m2, cua1, anal; two radial cells, 1st twice as long as 2nd; wing length 0.99 (0.97–1.01, n= 2) mm; breadth 0.45 (0.42–0.48, n=2) mm; costal ratio 0.57 (0.56–0.58, n=2). Halter stem brown, knob whitish.

Abdomen. Dark brown. Sternite 9 with slender halves ( Fig. 4 ); sternite 10 with one pair large setae. Two ovoid, subequal­sized, partially collapsed spermatheca with short, narrow necks ( Fig. 5 ), measuring 0.075 by 0.052 mm, 0.066 by 0.048 mm.

Male. As for female, with usual sexual differences. Lengths of flagellomeres in proportion of 27­16­13­12 ­ 12­12­14­14 ­14­15­40­30­37. Wing length 1.00 mm; costal ratio 0.52. Genitalia ( Fig. 6 ): Tergite 9 quadrate, as long as breadth, posterior margin truncate; posterior projection heptagonal with heavily sclerotized margins, apicolateral processes slender, moderately long, each with one apical seta, cercus short; sternite 9 0.2 as long as wide, posterior margin irregular. Gonocoxite stout, without mesobasal lobe; gonostylus 0.75 as long as gonocoxite, nearly straight, tip pointed. Parameres separated, each half represented by two heavily sclerotized, narrowly pointed recurved sclerites, one directed anteriorly, other bifid, directed posteriorly. Aedeagus stout; basal arms short, recurved; basal arch very low, irregular; apex not visible.

Distribution

Brachypogon (I.) borkenti n. sp. is presently known only from the steppe areas of the Argentinean provinces Mendoza and RÌo Negro.

Types

Holotype male, allotype female, ARGENTINA, Mendoza, prov. route no. 173, between Valle Grande and Nihuil, 10­XI­1994, G. Spinelli, sweep net (MLPA); paratype female, Río Negro, Somuncura plateau, Estancia “El Rincón”, 26/ 30­XI­1995, G. Spinelli, Malaise trap (MLPA).

Etymology

The species is named after our colleague and good friend, Dr. Art Borkent, in recognition of his superb contributions on systematics of Ceratopogonidae .

Figures

FIGURES 1 – 6. Brachypogon (Isohelea) borkenti, n. sp. 1 – 5. female; 6. male. 1. flagellum; 2. maxillary palpus; 3. wing; 4. sternite 9; 5. spermathecae; 6. genitalia. Scale bars = 0.05 mm.