Bradysia similigibbosa, 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 : 64-66

Bradysia similigibbosa sp. n.

( Figs 1 , 3–7 )

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). Paratypes, same data as holotype (1♂, MNHN; 5♂, SDEI; 2♂, CSCA); same locality, Malaise trap, 29.XI.–13.XII.1998, leg. N.J. Mary & M.E. Irwin (1♂, MNHN; 2♂, SDEI; 1♂, CSCA).

Description. Male. Head. Brown; eye bridge 4 facets wide. Antenna unicolourous brown except yellow scape and pedicel; basal part of 4th flagellomere 2.6–3.3 times as long as wide, total length of 4th flagellomere 3.1–3.9 times as long as wide ( Fig. 3 ); necks of flagellomeres bicoloured, edges contrasting brown to pale base; basal part of flagellomeres without sensilla. Maxillary palpus yellow slightly darker than scape and pedicel; segment 1 usually longer than segment 2 with 1–3 bristles and a dorsal flat patch of sensilla, segment 2 with one long outer bristle, segment 3 longest, 1.5 times longer than segment 1. Thorax ( Fig. 1 ). Pale brown in contrast to the brown head. Posterior pronotum bare. Anterior pronotum with 3–6 bristles. Episternum 1 with 6–14 bristles. Mesonotum with some stronger dorsocentrals and with 3–5 long and some weaker laterals. Scutellum with 4 strong and some minor bristles. Katepisternum slightly longer than high. Wing ( Fig. 5 ). Length = 2.3–2.6 mm; width/length = 0.36– 0.39. Wing membrane transparent, without macrotrichia; anal area well developed; veins distinct except weak mstem; all posterior veins without macrotrichia; R and R1 with dorsal macrotrichia only; apical part of R5 with ventral and dorsal macrotrichia; R1/R = 0.70–0.86; c/w = 0.58–0.67; r-m/bM = 0.64–0.90. Halteres yellow. Legs yellow; coxal bristles pale. Foretibia with some longer bristles within vestiture; tibial organ on foretibia ( Fig. 4 ) with a comb-like row of bristles wider than half of tibial apex width. All tibial spurs long; spurs of midtibia and hind tibia equal. Claws with fine teeth. Abdomen ( Fig. 1 ). Pale brown, same colour as thorax, sometimes slightly darker. Hypopygium ( Fig. 7 ). As brown as abdomen. Gonocoxites wider than long, with normal setosity; ventral, inner-side of gonocoxites u-shaped and lighter, without basal lobe of bristles. Gonostylus ( Fig. 6 ) 2.5 to 3.0 times as long as wide, basal and apical inner-side of gonostylus impressed, widest at middle; apex of gonostylus distinctly tapered and with a subapical group of 4 long spines, and one apical spine on the adjacent outer side. Tegmen trapezoidal, with long and strongly sclerotized basal apodemes; area of teeth large, with numerous strong, triangular teeth. Ejaculatory apodeme short and strong.

Body size: 2.5 to 3.0 mm.

Female. Unknown.

Etymology. The species epithet refers to the similarity of this species to Bradysia gibbosa Vilkamaa, Hippa & Mohrig, 2012 . The Latin word similis means similar.

Discussion. Bradysia similigibbosa resembles B. gibbosa Vilkamaa, Hippa & Mohrig, 2012 , which was also described from New Caledonia. They share a similar gonostylus shape, but that of B. similigibbosa is more elongate than that of B. gibbosa . The ratio of length vs. width of gonostylus is 2.5–3.0 in B. similigibbosa compared to 2.2–2.6 in B. gibbosa . Despite the small overlap, a good diagnostic feature is the spine on the outside of the gonostylus which is lacking in B. gibbosa . In contrast to the original description of B. gibbosa , which states that the number of subapical spines (megasetae sensu Vilkamaa et al. 2012c) is three, all specimens of B. gibbosa examined by us have four subapical spines (see below). Therefore this is not a useful diagnostic character. Further differences between these species are the number of facets forming the eye bridge (2-3 in B. gibbosa vs. 4 in B. similigibbosa ), colour of scape and pedicel (yellow vs. slightly paler than flagellum), thorax colour (pale brown vs. brown) and the general body size (2.5–3.0 mm vs. 2.1–2.7 mm). Bradysia similigibbosa and B. gibbosa could not be placed in one of Bradysia species groups of Menzel & Mohrig (2000). These species have the following characters in common: bicoloured neck of flagellomeres, segment 2 with a long bristle, claws with teeth, scutellum with 4 strong bristles, macrotrichia on both sides of the apex of R5, ventral inner-side of gonocoxites u-shaped, a trapezoidal tegmen and a short ejaculatory apodeme. On the basis of this set of characters both species are placed in the newly erected Bradysia gibbosa group. This species group appears to be related to 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 3 – 7. Bradysia similigibbosa, holotype, male. 3. 4 th flagellomere, lateral. 4. Tibial organ on inner-side of foretibia. 5. Wing. 6. Gonostylus, ventral. 7. Hypopygium, ventral. Scale bars: Figs 3, 4, 6, 7 = 0.1 mm; Fig. 5 = 1 mm.