Hercostomus (Hercostomus) siveci Zhang, Yang and Masunaga

Zhang, Lili, Yang, Ding & Masunaga, Kazuhiro, 2005, (Diptera, Dolichopodidae), Zootaxa 811, pp. 1-8 : 2-5

Hercostomus (Hercostomus) siveci Zhang, Yang and Masunaga , sp. nov.

( Figs. 1–5 )

Diagnosis. — Postocular bristles entirely black. Antenna black; first flagellomere 1.8 times longer than wide. Fore coxa yellow, mid and hind coxae blackish brown. Hind femur tinged with brownish on tip. Apicoventral lateral lobe on epandrium slender and curved apically with 2 apical bristles, basiventral lateral lobe with 3 bristles.

Description. — Male. Body length 5.1 mm, wing length 5.1 mm.

Head metallic green with pale gray pollen. Face narrowing downward, narrower than first flagellomere. Hairs and bristles on head black; postocular bristles entirely black. Antenna ( Fig. 2 ) black; first flagellomere 1.8 times longer than wide; arista black, minutely pubescent, with basal segment 0.7 times as long as apical segment. Proboscis blackish brown with black hairs; palpus black with black hairs and 1 black apical bristle.

Thorax metallic green with pale gray pollen. Hairs and bristles on thorax black; 6 strong dc, 7 irregularly paired acr; scutellum with 2 pair of bristles (basal pair very short and hair­like). Propleuron pale haired with 1 black bristle on lower portion. Legs yellow; fore coxa yellow, mid and hind coxae blackish brown. Hind femur tinged with brownish on tip. Hind tibia brown. Fore tarsi from tip of tarsomere 1 onward brownish; mid and hind tarsi dark brown to black from tip of tarsomere 1 onward. Hairs and bristles on legs black, mid and hind coxae each with 1 outer bristle, mid and hind femora each with 1 anterodorsal preapical bristle. Fore tibia with 1 ad and 2 pd, apically with 3 short bristles; mid tibia with 4 ad (basal bristle rather short) and 2 pd, apically with 4 bristles; hind tibia with 4 ad (basal bristle rather short), 5 pd (basal bristle rather short) and 1 pv, apically with 3 bristles. Fore tarsomere 1 with 1 v at base. Relative lengths of tibia and 5 tarsomeres: fore leg: 2.5: 1.2: 0.5: 0.5: 0.4: 0.4; mid leg: 3.4: 1.9: 1.0: 0.7: 0.5: 0.4; hind leg: 4.0: 1.1: 1.4: 1.0: 0.5: 0.4. Wing ( Fig. 1 ) hyaline, tinged with grayish; veins brown, R4+5 and M distinctly convergent apically; CuAx ratio 0.8. Calypter yellow with black hairs. Halter yellow.

Abdomen metallic green with pale gray pollen, hairs and bristles black. Hypopygium ( Figs. 3­5 ): Epandrium distinctly longer than wide, narrowing apically; apicoventral lobe slender and curved apically with 2 apical bristles, basiventral lobe with 3 bristles; cercus long, band­like with marginal bristles; hypandrium trifurcated with middle process rather wide and acute apically, the lateral process slender apically, phallus slender.

Female. Unknown.

Type material. — Holotype ɗ, TAIWAN: Taitung, Slital (23°10'52''N, 121°01'32''E), 810 m, sweep net, 4. iv. 1996, I. Sivec and B. Horvat (SMNH).

Etymology. — The new species is named after Dr. I. Sivec (Ljubljana).

Comments. — The new species is somewhat related to the Hercostomus hamatus ­ group ( Wei, 1997). The hamatus ­group is characterized mainly by the hind femur with dark tip, and cercus nearly triangular with several finger­like marginal processes and strong bristles. The group contains two known species from Europe, H. chetifer (Haliday) and H. separatus d’Assis­Fonseca , and twenty­six known species from continental China.

The new species is somewhat similar to H. chaeturus Yang and Grootaert in the epandrium acute apically, but may be separated from the latter by the entirely metallic green thorax and a well developed basiventral epandrial lobe with 3 bristles. In H. chaeturus , the metapleuron is yellow and the epandrium lacks a basiventral lateral lobe ( Yang and Grootaert 1999). In Becker’s key (1922), the new species will run to the 9th couplet and may be related to H. ovatus Becker , but may be separated from the latter by the long and band­like cercus. In H. ovatus , the cercus is short and triangular.

Seven species from Taiwan seem to be related to the hamatus ­group according to Becker’s key (1922). Zhang, Yang and Masunaga (2004) described other three species of the group from Taiwan: Hercostomus chiaiensis , H. hualienensis and H. taitungensis . A key to the related species of the hamatus ­group from Taiwan are provided as follows.

1. Antenna black with scape reddish yellow; fore tarsomeres 45 with short ventral bristles ........................................................................................ Hercostomus promotus Becker

­ Antenna wholly black, at most with wide ventral surface of scape brownish yellow; fore tarsus without short ventral bristles ...................................................................... 2

2. Apical 1/3 of hind tibia black ......................................... Hercostomus porrectus Becker

­ At most apex of hind tibia black .................................................................................. 3

3. All coxae yellow ........................................................ Hercostomus lucidiventris Becker

­ Only fore coxa yellow .................................................................................................. 4

4. Tarsi modified ............................................................................................................... 5

­ Tarsi simple .................................................................................................................. 8

5. Fore tarsus modified ..................................................................................................... 6

­ Fore and (or) mid tarsi modified .................................................................................. 7

6. Fore tarsomeres 3–5 flattened, and tarsomere 5 black except narrow base ................... ..................................................... Hercostomus chiaiensis Zhang, Yang and Masuanag

­ Fore tarsomeres 3–5 not flattened, and tarsomere 5 white.............................................. .................................................. Hercostomus taitungensis Zhang, Yang and Masuanag

7. Mid tarsus not flattened, but tarsomere 1 with slender lateral hairs at apical 1/3 and tar­ somere 2 with 4–5 long lateral hairs, and tarsomeres 4–5 white .................................... ........................................................................................ Hercostomus albidipes Becker

­ Mid tarsomeres 3–5 flattened and black from apex of tarsomere 3 onward ................... ..................................................................................... Hercostomus incrassatus Becker

8. Halter blackish brown ...................................................... Hercostomus inclusus Becker

­ Halter yellow ................................................................................................................ 9

9. Cercus triangular ........................................................................................................ 10

­ Cercus long and nearly band­like, without distinct finger­like processes ...................... ............................................................................................. Hercostomus siveci sp. nov.

10. Cercus acute without finger­like processes apically ........... Hercostomus ovatus Becker

­ Cercus with 3 finger­like processes apically................................................................... ................................................. Hercostomus hualienensis Zhang, Yang and Masunaga

Figures

FIGURES 1 – 5. Hercostomus (Hercostomus) siveci sp. nov. (male). 1. Wing; 2. antenna, lateral view; 3. hypopygium (excluding cercus), lateral view; 4. cercus, lateral view; 5. hypandrium, ventral view.