Bradysia irwini, Köhler, Arne & Menzel, Frank, 2013

Köhler, Arne & Menzel, Frank, 2013, New records of Black Fungus Gnats (Diptera: Sciaridae) from New Caledonia, with the description of two new Bradysia species and an updated checklist, Zootaxa 3718 (1), pp. 63-72 : 66-68

Bradysia irwini sp. n.

( Figs 2 , 8–12 )

Material examined. Holotype, male. NEW CALEDONIA: Province South, Mt. Koghis, 17 km NNE of Noumeá, 550 m a.s.l. Malaise trap, 13.XII.–20.XII.1998, leg. N.J. Mary & M.E. Irwin (MNHN).

Description. Male. Head. Brown; eye bridge 3–4 facets wide. Antenna slightly paler, scape and pedicel yellowish; surface of flagellomeres rough, basal part of 4th flagellomere 2.3 times as long as wide, total length of flagellomere 4 ( Fig. 8 ) 2.8 times as long as basal wide; setae on basal part of flagellomeres slightly shorter than width of flagellomeres with small sensilla among them. Maxillary palpus yellow; segment 1 as long as segment 2, with 2 bristles and a dorsal flat patch of sensilla; segment 2 with one long outer bristle; segment 3 is longest, 1.3 times as long as segment 1. Thorax ( Fig. 2 ). Yellow-brown, posterior gradually darkened; thoracic bristles pale. Posterior pronotum bare. Anterior pronotum with 2 bristles. Episternum 1 with 6 bristles. Mesonotum with some stronger dorsocentrals (broken and missing on holotype) and with 4–5 longer and some weaker laterals. Scutellum with 2 strong and some shorter bristles. Katepisternum yellow coloured and as long as high. Wing ( Fig. 10 ). Length = 1.6 mm; width/length = 0.40. Wing membrane transparent, without macrotrichia; anal area well developed; all posterior veins without macrotrichia; veins distinct except slight m-stem; R, R1 and R5 only with dorsal macrotrichia; R1/R = 0.48; c/w = 0.62; r-m/bM = 0.77. Halteres brownish. Legs yellow; coxal bristles pale. Foretibia without small bristles among vestiture; tibial organ ( Fig. 9 ) with a comb-like row of 9 bristles, more than half of tibial apex wide. Tibial spur slightly longer than width of tibial apex of foretibia, apically slightly bent towards tibia. Hind tibia with a posterodorsal row of dark bristles, extend 0.7 of tibial length. Claws with fine teeth. Abdomen ( Fig. 2 ). Brown, with dark bristles. Hypopygium ( Fig. 12 ). As brown as abdomen. Gonocoxites longer than wide, normal setosity; ventral, inner-side of gonocoxites v-shaped and without basal lobe of bristles. Gonostylus ( Fig. 11 ) narrow, 2.75 times as long as wide and swollen at middle; apex of gonostylus rounded, slightly bent inwards and subapically with 2 equally long spines. Tegmen trapezoidal and membranous, with short and strongly sclerotized basal apodemes; area of teeth large, with strong, triangular teeth. Ejaculatory apodeme short and strong.

Body size: 1.6 mm.

Female. Unknown.

Etymology. We dedicate this new species to the collector Michael E. Irwin, Vail, Arizona [formerly of Urbana, Illinois] ( USA), who sent us samples from different regions for our studies in the systematics of Sciaridae .

Discussion. Amongst the New Caledonian sciarids, B. irwini is similar to B. gemellata Vilkamaa, Hippa & Mohrig, 2012 in having two gonostylar spines (megasetae sensu Vilkamaa et al. 2012c). This reduced number of gonostylar spines was construed as a unique feature of B. gemellata among the New Caledonia sciarids (Vilkamaa et al. 2012c). Bradysia irwini may be distinguished from B. gemellata by the longer flagellomeres, the toothed claws, the inner-side of gonocoxites v-shaped and the slight subapical emargination of the gonostylus. Furthermore the c/w and r-m/bM ratios differ (c/w = 0.62 in B. irwini vs. c/w = 0.70–0.85 in B. gemellata ; r-m/bM = 0.77 in B. irwini vs. both veins subequal in B. gemellata ). In contrast to B. gemellata (belonging to B. hilaris group), B. irwini could be placed in the B. fungicola group sensu Menzel & Mohrig (2000). Characters like the long bristle on segment 2, claws with fine teeth and the v-shaped gonocoxal inner-side support this classification, although the absence of bristles in the vestiture of the foretibia and the trapezoidal tegmen are not typical characters of the B. fungicola group.

Figures

FIGURES 1, 2. Habitus of males, genitalia removed, lateral. 1. Bradysia similigibbosa, holotype. 2. Bradysia irwini, holotype. Scale bars: 1 mm.

FIGURES 8 – 12. Bradysia irwini, holotype, male. 8. 4 th flagellomere, lateral. 9. Tibial organ on inner-side of foretibia. 10. Wing. 11. Gonostylus, ventral. 12. Hypopygium, ventral. Scale bars: Figs 8, 9, 11, 12 = 0.1 mm; Fig. 10 = 0.5 mm.