Hercostomus setitibia Kazerani & Pollet

Kazerani, Farzaneh, Khaghaninia, Samad, Talebi, Ali Asghar, Persson, Magnus & Pollet, Marc, 2017, Eight new species of Dolichopodinae (Diptera: Dolichopodidae) from northern Iran, Zootaxa 4242 (1), pp. 111-141 : 130-133

Hercostomus setitibia Kazerani & Pollet sp. nov.

( Figs 26–29 )

Diagnosis. Male. Rather large species, with dark metallic green body. Face silvery white, narrow. All postocular bristles black. Antenna entirely black, with postpedicel rounded subrectangular, about 1.3 x as long as deep. Legs nearly entirely black, with only coxa I–II, trochanters I–II, knees of femur I–III and tarsus I at least partly pale. Tibia II with conspicuous brush of inclined av and long erect vt bristles in basal ½ (MSSC). Tibia I with 4 very strong curved preapical bristles (MSSC). Tarsomeres taI3-5 with rows of long rather erect ds setae (MSSC). Hypopygium mainly blackish brown with basoventral part of epandrium reddish yellow. Cercus large, black, crescent-shaped, about 2.3 x as long as wide, with multiple black marginal setae, and a slender apicodorsal process bearing three curved bristles.

Description. Male. Body length: 5.3 mm; wing length: 5.2 (n=1). Head. Face silvery white, distinctly narrowing below antenna, then widening towards clypeus, at narrowest width about 0.3 x as wide as postpedicel (length), bare. Frons dark metallic green, entirely dusted silvery white. Occiput dark metallic green, slightly convex. Palpus rather small, about 1/6 of eye, ovoid, dark brown, with black pubescence and 1 strong black apical bristle. Proboscis dark brown. Eyes red with short white pubescence. All postocular bristles black. Two-three pairs of black postocellar bristles. Antenna entirely black, postpedicel rounded subrectangular, 1.3 x as long as deep, and about as long as scape and pedicel combined, with silverish pruinosity; stylus dorsal, inserted at apical 1/3, about 1.3 x as long as first three antennal segments combined, with short pubescence. Thorax. Entirely dark metallic green, brilliant; pleura and metapleura with distinct greyish pruinosity; scutellum bare on dorsum, with 2 strong median, and two thin, smaller lateral bristles. Thoracic bristles black. Six dc; 12 ac, biserial, reaching almost to level of 5th dc, 2 x as long as distance between rows; 1 large and 2 minute ant pprn, 1 internal and 1 external bas pprn, 1 psut ial, 1 equal-sized sut ial, about as long as dc, 2 npl, 2 spal, and 1 pal bristles; with additional short pubescence on anterior part of thorax. Upper proepisternum with about 5 black and many long yellow setae, lower proepisternum with one strong black bristle, and multiple, rather long and thin yellow setae. Wing. Only very slightly infuscate. Veins R4+5 gently curved, and M1+2 with smooth bend in apical ½ of wing, both converging towards wing apex, and parallel near apex. Proximal section of M1+2 0.9 x as long as apical section. Proximal section of CuA1 1.5 x as long as apical section. CuA x ratio: 2.6. Halter white, calypteral fringe with apical setae black and basal ones paler (brownish). Legs. Nearly entirely black, with only coxa I–II, trochanters I–II, knees of femur I–III and tarsus I at least partly pale. Bristles black. All coxa with greyish pruinosity. Coxa I with apical margin, coxa II with apical 1/5 (anterior and posterior face), and coxa III near apex (anterior face) reddish yellow; latter with external bristle inserted at about middle. Trochanter I entirely reddish, trochanter II with basal ½ reddish yellow. All femora with narrow yellow knees; femur I with 1 small av and 1 larger pv preapical bristle; femur II with 1 strong ad, 1 smaller av and 1 pv preapical bristles; with 4 vt and 5 pv bristles on about basal ¼, about 0.8 x as long as femur is long; femur III with 1 strong ad preapical bristle, 1 small av and 1 larger pv preapical bristles; with multiple ad and vt rows of thin black strongly inclined setae on entire length, longest at middle and about as long as femur is deep (MSSC); with rather erect ds bristles on about basal 1/3, about 0.5 x as long as femur is deep. Tibia I slightly swollen towards apex with 4 ad (basalmost bristle smaller) and 4 pd bristles, longest 1.6 x as long as tibia is deep; with 2 pv bristles, about 2.2 x as long as tibia is deep; with 4 apv bristles, with two exceptionally long and distinctly curved ones, 4 x as long as tibia is deep (MSSC). Tibia II slightly swollen in basal ½, with 5 ad and 3 pd bristles, longest ones 2.7 x as long as tibia is deep; with dense av pubescence of thin setae on basal 2/3, about as long as tibia is deep, and 2 av bristles, basalmost one 1.7 x as long as tibia is long (MSSC); with group of rather thin erect vt bristles on basal ½, 2.5 x as long as tibia is long (MSSC); and with 5 ap bristles. Tibia III with 7 ad, and 5 large and some smaller pd bristles, longest 3 x as long as tibia is deep, and with 2 ap bristles; with distinct pd row of bristles on about apical 3/4; with dense vt and av pubescence, including 4 distinct vt bristles, about as long as tibia is deep. Tarsus I with taI1 black, becoming paler from taI2 onwards, with taI3-5 yellowish brown; with taI1 slightly curved towards apex, with vt pubescence, as long as taI1 is deep, and two longer erect vt bristles at basis, longest one 3 x as long as taI1 is deep; taI3-5 with rows of rather erect ds setae, about 2 x as long as taI3-5 are deep (MSSC). Tarsus II with taII1 with short vt bristle at basis, taII1-4 with short pv pubescence along entire length, about as long as tarsomeres are deep, and each with 4–6 short robust apical bristles. Tarsus III with taIII1-2 with strong vt bristles among dense pubescence, about as long as taIII1-2 is deep. Lengths ratio of femur/tibia/tarsomeres 1–5 in leg I: 5.1/5.2/2.6/1.4/1.2/1.2/1, in leg II: 8.2/9.2/4.3/2.2/1.8/1.5/1, and in leg III: 7.8/9.8/3.2/3.6/2.4/1.6/1. Abdomen. With 5 pubescent segments, T6 small but visible, about 0.6 x as long as T5. Tergites entirely dark metallic green, brilliant, concolorous with mesonotum, with black bristles; T1-5 with strong bristles on posterior margin. Sternites dark metallic green, with short pale pubescence. Hypopygium ( Fig. 29 ) distinctly pedunculate with epandrium mainly brownish black, with ventral half largely reddish yellow; hypandrium short, triangular; phallus dark brown with strong, hook-like subapical dorsal process; bv epandrial lobe small with long yellow seta, apv lobe well-developed with 3 yellow setae on caudal margin; surstylus yellow, with ventral surstylar lobe short, with distinctly enlarged triangular apex, and dorsal surstylar lobe larger, with ovoid apex, bearing one strong black ds bristle; postgonites slender with triangular apex; cerci large, black, crescent-shaped, about 2.3 x as long as wide, with multiple black setae, and slender apicodorsal process bearing 3 curved bristles. Female. Unknown.

Type material. HOLOTYPE ♂, IRAN: Guilan, Ghazichak (sampling site: Guilan _8), 36°45′57.54"N, 50°19′35.22"E, 1803 m, 27.vii–3.viii.2010, MT, leg. Mohammad Khairandish & Ahmad Nadimi ( TMUC) . PARATYPES: IRAN: 1♂, same data as holotype ( MAPC) ; 1♂, Guilan, Orkom (sampling site: Guilan _5), 36˚45.739′N, 50°18.198′E, 1201 m, 22–29.vi.2010, MT, leg. M. Khairandish & A. Nadimi ( ICHMM) .

Distribution and ecology. The species has thus far only been collected in forest habitats in the northern Iranian province of Guilan.

Etymology. The species is named after its most conspicuous feature, namely the brush of black ventral setae on tibia II.

Remarks. Hercostomus setitibia sp. nov. clearly belongs to the Hercostomus nigrilamellatus species group sensu Pollet et al. (2010). This group contains large, dark-coloured species with a large hypopygium and a crescent-shaped cercus. MSSCs are found in the fore tibia (curved preapical bristle in H. nigriplantis (Stannius, 1831) , H. nigrilamellatus (Macquart, 1827) and H. setitibia sp. nov.), the mid tarsus (strong vt bristles on taII 1 in H. sahlbergi (Zetterstedt, 1838) and H. vockerothi Assis Fonseca, 1976 ), and as observed for the first time, also in the mid tibia (brush of long av bristles in H. setitibia sp. nov.).

In the keys of Parent (1938) and Stackelberg (1933), H. setitibia sp. nov. might run to the couplet that leads to H. nigrilamellatus , if the presence of more than one curved preapical bristle on tibia I would be ignored. Both species differ quite substantially and the most useful diagnostic features are the following:

1 Tibia II with conspicuous brush of inclined long av erect black bristles in basal ½ ( Fig. 28 ). Tibia I with 4 very strong curved preapical black bristles. Wing nearly hyaline. Epandrium ( Fig. 29 ) with basodorsal part reddish yellow and relatively small apv epandrial lobe. Cercus ( Fig. 29 ) rather narrow, with a slender apicodorsal process bearing three curved bristles.................................................................... Hercostomus setitibia sp. nov. Kazerani & Pollet ( Iran)

- Tibia II with normal vestiture, without av brush of bristles. Tibia I with 1 curved preapical black bristle. Wing slightly, evenly infuscate. Epandrium nearly entirely dark with massive apv epandrial lobe. Cercus broader, without apicodorsal process and regular arrangement of tubercles on apical margin, bearing curved bristles....................................................................................... Hercostomus nigrilamellatus (Europe, eastern and southern Russia)

Figures

FIGURE 29. Hercostomus setitibia sp. nov., male, hypopygium. Abbreviations: apv lobe: apicoventral epandrial lobe, bv lobe: basoventral epandrial lobe, cerc: cercus, dsur: dorsal surstylar lobe, hyp: hypandrium, pgo: postgonites, vsur: ventral surstylar lobe.

FIGURES 26 – 28. Hercostomus setitibia sp. nov., male. (26) habitus: (27) antenna; (28) tibia II.