Hercostomus spathulatus Negrobov, Kumazawa, Tago & Sato

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 : 72-74

Hercostomus spathulatus Negrobov, Kumazawa, Tago & Sato sp. nov.

( Figs 5 A–I, 8E)

Hercostomus sp. № 8t. Tago, 2010: 9.

Type material. HOLOTYPE Ƌ, labeled: Japan, Tokyo, Katsushika ward, Yotsugi , 27.vi.2010, leg. T. Tago ( OMNH) . PARATYPES: 4 Ƌ, 4 ♀, Japan, Tokyo, Katsushika ward, Yotsugi , 27, 29.vi.2010, leg. T. Tago (2 Ƌ, 3 ♀ OMNH, 2 Ƌ, 1 ♀ VSU), 1 Ƌ, Okinawa, Ishigakijima, Nosoko, 24.vi.1998, leg. M. Sato (RTM).

Description. Male. Head with frons dull with dense silvery-white pollinosity. Face narrow with dense white pollinosity with golden tinge, without hairs, not reaching lower eye margin, middle part equal to postpedicel width. Proboscis brown. Palpus yellow, with 1 black seta and black hairs. Antenna ( Fig. 5 B) short, black, scape yellow below. Postpedicel pointed apically, slightly longer than wide. Stylus placed on dorsal side of postpedicel, nearer to apex, with short hairs. Ratio of postpedicel length to width and stylus length: 1.5: 1.4: 3.1. Postocular setae lightyellow. Thorax dark-green with purple tinge, with white pollinosity. Pleura green, with dense silvery-white pollinosity. Propleuron with 1 black seta and yellow hairs below and with yellow hairs above. Scutellum bare above, with 2 strong black lateral setae and small marginal hairs. Legs yellow, coxae green, apex of fore and mid coxae yellow, apex of 4th and 5th segments of mid tarsus black, apex of fore and hind tarsi darkened. Femora without long hairs below. Fore femur with short preapical outer seta. Fore tibia without long apicoventral seta, with 2 long and 1 short anterodorsal, 2 posterodorsal and 1 posteroventral setae, with row of small anteroventral setae in apical 2/3. Tarsomeres of fore tarsus ( Fig. 5 H) with small hairs, 2nd–4th segments shortened. Ratio of length of fore tibia and tarsomeres (from 1st to 5th): 5.8: 2.7: 0.7: 0.5: 0.3: 0.7. Mid femur with 1 long preapical outer seta. Mid tibia with 3 long anterodorsal, 2 posterodorsal and 2 anteroventral setae. Tarsomeres of mid tarsus with short ventral setae. Apex of tarsomeres 4 and 5 ( Figs 5 G, I) of mid tarsus widened, with short black hairs laterally. Ratio of length of mid tibia and tarsomeres (from 1st to 5th): 7.9: 4.6: 3.5: 2.8: 1.6: 1.4. Hind coxa with 1 black outer seta. Hind femur without preapical outer seta, with dense rows of black anterodorsal setae. Hind tibia thickened apically, with 4 long anterodorsal, 4 long posterodorsal and 5–6 short anteroventral setae. Ratio of length of hind tibia and tarsomeres (from 1st to 5th): 9.5: 3.4: 5.1: 3.1: 1.7: 1.2. Tarsomere 1 of hind tarsus with 1–2 small ventral setae, other segments of hind tarsus with small hairs. Wing hyaline. 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—3.1: 0.9. M1+2 gently curved. R4+5 and M1+2 convergent apically. Ratio of m-cu to apical part of M3+4—1.9: 2.4. Anal angle obtuse. Calypter yellow with yellow cilia. Halter yellow. Abdomen bright green with purple tinge, with dark stripes on anterior edges of tergites, with black setae and hairs, with dense silvery-white pollinosity. Abdominal segment 7 bright black, without pollinosity. Abdominal segment 8 dull black with small black hairs. Epandrium bright black, without pollinosity, oval, longer than wide. Surstylus black. Phallus black, with yellow apex. Hypandrium ( Figs 5 A, C) yellow. Cercus ( Fig. 5 D) brown, shorter than epandrium, triangular, with processes at apex and on dorsal side, with long black hairs. Female. Face broader than postpedicel width, face white with golden tinge. Length (mm): body: 2.9–3.1, wing: 3.1–3.4.

Etymology. The species is named for the widened apical tarsomeres on the mid tarsus.

Remarks. According to Stackelberg (1934), the new species is included in the first group of Hercostomus (femora yellow, postocular setae yellow, antennae partly yellow). The new species differs from all species in the fauna of China on the basis of the widened tarsomere 5 of mid tarsus. In the key to Palaearctic species ( Negrobov et al. 2008), the new species runs to Hercostomus gansuensis Yang, 1996 , but can be distinguished from the latter by the morphology of the hypopygium and following characters:

- Thorax and abdomen without silvery pollinosity. Tarsomere 5 of mid tarsus not widened. Fore coxa yellow...................................................................................... Hercostomus gansuensis Yang, 1996 - Thorax and abdomen with silvery pollinosity. Tarsomere 5 of mid tarsus widened. Fore coxa dark............................................................................................... Hercostomus spathulatus sp. nov.

Figures

FIGURE 5. Hercostomus spathulatus sp. nov. (A) hypopygium, left lateral view; (B) antenna, lateral view; (C) hypopygium, ventral view; (D) left cercus, dorsal view; (E) dorsal lobe of surstylus, left lateral view; (F) ventral lobe of surstylus, left lateral view; (G) fore tarsus, lateral view; (H) mid tarsus, dorsal view; (I) mid tarsus, lateral view.