Hercostomus spinitibialis Negrobov, Kumazawa & Tago

Negrobov, O. P., Kumazawa, T., Tago, T. & Sato, M., 2016, New species of Hercostomus Loew, 1857 (Dolichopodidae, Diptera) from Japan, Zootaxa 4158 (1), pp. 65-80 : 74-76

Hercostomus spinitibialis Negrobov, Kumazawa & Tago sp. nov.

( Figs 6 A–E, 8F)

Hercostomus sp. № 6t. Tago, 2010: 9.

Type material. HOLOTYPE Ƌ, labelled: Japan, Saitama pref., Iwabuchi, Hannou City , 17.vi.2006, leg. Tago ( OMNH) . PARATYPES: 1 Ƌ, 1 ♀, same data as holotype (1 ♀ OMNH, 1 Ƌ VSU) .

Description. Male. Head with frons green with blue tinge and white pollinosity. Face silvery-white, not reaching lower eye margin, middle part narrower than postpedicel width. Proboscis and palpus yellow, palpus with black hairs. Antenna ( Fig. 6 C) yellow, apical half of postpedicel brown. Postpedicel obtuse apically, longer than wide, with small ventral apical process. Ratio of 1st and 2nd segments of stylus: 2.9: 2.3. Ratio of postpedicel length to width and stylus length: 2.8: 1.5: 5.2. Stylus placed at middle of dorsal part of postpedicel, with short hairs. Postocular setae black. Thorax green with metallic tinge, with weak silvery pollinosity. Pleura metallic green, with grey-white pollinosity. Propleuron with 1 black seta below and group of black hairs above. Scutellum bare above, with 2 strong black lateral setae and small marginal hairs. Legs yellow, mid coxa brown in basal half, with black setae and hairs. Tarsomeres simple, not widened. Femora without long hairs below. Fore tibia without long apicoventral seta, with 2 strong anterodorsal and 1 strong posterodorsal setae, with row of small anteroventral hairs in upper 2/3. Ratio of length of fore tibia and tarsomeres (from 1st to 5th): 8.5: 4.5: 2.5: 2.1: 1.5: 1.0. Mid femur with 1 preapical seta above on outer side and 2–3 small preapical hairs on inner side. Mid tibia with 3 strong and 1 small anterodorsal, 2 posterodorsal and 1 ventral setae. Tarsomere 1 of mid tarsus with 3–4 short ventral setae. Ratio of length of mid tibia and tarsomeres (from 1st to 5th): 10.0: 2.5: 3.9: 2.8: 1.7: 1.0. Hind coxa with 1 black outer seta. Hind femur with 1 preapical outer seta. Hind tibia with 3 long anterodorsal, 3 posterodorsal and 3 short anteroventral setae. Ratio of length of hind tibia and tarsomeres (from 1st to 5th): 14.1: 4.7: 4.2: 2.9: 1.8: 1.6. Tarsomere 1 of hind tarsus without strong dorsal setae, with 2–3 small ventral setae. Wing darkened. Costal vein without thickening at tip of R1. Ratio of costal section between R2+3 and R4+5 to that between R4+5 and M1+2—2.6: 0.7. R4+5 and M1+2 convergent apically. Ratio of m-cu to apical part of M3+4—1.8: 2.9. Anal angle obtuse. Calypter yellow with black cilia. Halter yellow. Abdomen metallic green with blue tinge, with purple stripes on lateral parts of tergites, with black setae and hairs. Abdominal segment 8 black, covered by short black hairs. Epandrium ( Figs 6 A, E) black, roundish, approximately as long as wide. Asymmetrical epandrial lobe in form of wide-oval plate placed on right side. Surstylus ( Fig. 6 D) yellow, brown at apex. Cercus yellow with darkened apex, with black hairs, almost 2 times as long as width. Female. Similar to male except: face 2 times broader than postpedicel width (1.8: 0.9). Length (mm): body: 2.8–3.0, wing: 2.7–2.8.

Etymology. The species is named for the claw-like setae on the hind tibia.

Remarks. According to Stackelberg (1934), the new species is included in the third group of Hercostomus (femora yellow, postocular setae black). In the key to Palaearctic species (Selivanova et al. 2012), the new species runs to Hercostomus beijingensis Yang, 1996 , but can be distinguished from the latter by the morphology of hypopygium and following characters:

- Postpedicel with sharp apex. Cercus oval, sharply curved at base, oval at apex............ Hercostomus beijingensis Yang - Postpedicel with blunt apex. Cercus narrow long, straight, not curved at base........... Hercostomus spinitibialis sp. nov.

In the key to Chinese species ( Yang et al. 2011), the new species runs to Hercostomus xiaolongmensis Yang & Saigusa, 2001 , but can be distinguished from the latter by the following characters:

- Antennae black. Postpedicel approximately as long as wide. Base of abdomen yellow. Pleura brown-yellow. Cercus curved................................................................. Hercostomus xiaolongmensis Yang & Saigusa - Antennae mostly yellow. Postpedicel longer than wide. Base of abdomen and pleura green. Cercus straight......................................................................................... Hercostomus spinitibialis sp. nov.

Figures

FIGURE 6. Hercostomus spinitibialis sp. nov. (A) hypopygium, left lateral view; (B) hypopygium, right lateral view; (C) antenna, lateral view; (D) surstylus, lateral view; (E) hypopygium, ventral view.