Parahercostomus Yang, Saigusa & Masunaga

SCOTT E. BROOKS, 2005, Systematics and phylogeny of Dolichopodinae (Diptera: Dolichopodidae), Zootaxa 857, pp. 1-158 : 89-90

Genus Parahercostomus Yang, Saigusa & Masunaga

( Fig. 21 A–E)

Parahercostomus Yang, Saigusa & Masunaga, 2001: 176 . Type species: Hercostomus zhongdianus Yang [Oriental], by original designation.

Recognition. This genus can be recognized by the following combination of characters: sutural, presutural and acrostichal setae absent; vertical setae weaker than postverticals, hind basitarsus with 1–3 dorsal setae, male with R2+3 and R4+5 thickened in basal part.

Description. Head: Vertex slightly excavated, 1 pair of weak vertical setae, about equal to postverticals. Frons about 1.3 x wider than high in male, about 1.7 x wider than high in female, sides nearly parallel. Face and clypeus narrow in male, broad in female, lower margin straight, not reaching lower eye margin. Palp smaller in male, rounded below, with setae on outer surface and a weak apical seta. Antenna: Scape subrectangular, somewhat elongated in male, medioventral process very weakly developed in female, absent in male; pedicel short; first flagellomere oval, apex rounded to subtriangular; arista dorsal, 2­segmented, basal segment somewhat elongated, distal segment weakly pubescent. Lower postocular setae fine. Postvertical setae stronger than uppermost pair of postoculars.

Thorax: Acrostichals absent; 6 dorsocentrals, aligned; 1 outer posthumeral, 1 inner posthumeral weakly developed or absent; 2 notopleurals; presutural and sutural absent; 2 supraalars; 1 postalar. Upper part of propleuron with cluster of fine hairs, lower part of propleuron with 1 strong prothoracic seta and fine hairs; pleural surface in front of posterior spiracle and metepisternum bare. Scutellum with 1 strong inner seta and a minute outer hair on lateral margin, posterior margin with or without (e.g., P. triseta Yang, Saigusa & Masunaga ) fine hairs.

Legs: Pulvilli developed normally on all legs. Foreleg: Apex of basitarsus and distal tarsomeres of male piliferous ventrally. Midleg: Femur with 1 anterior preapical seta. Hindleg: Coxa with strong lateral seta slightly below middle; femur with 1 anterodorsal preapical seta; tibia of male with posterodorsal ridge apically; basitarsus distinctly longer than second tarsomere with 1–3 anterodorsal setae, 1 strong basiventral seta, longer than width of basitarsus, 2–4 weaker ventral setae, male with dentiform process posterobasally.

Wing: Brownish to mainly hyaline. Costa thickened beyond R 1 in male; R2+3 nearly straight; R4+5 curved posteriorly in distal section; R2+3 and R4+5 of male thickened in basal half to three­quarters; distal section of M beyond crossvein dm­cu nearly straight or with weak sinuous anterior bend before middle and posterior curve in distal section, ending near or slightly before wing apex, subparallel or convergent with R4+5; crossvein dm­cu subequal to distinctly shorter than distal section of CuA1.

Abdomen: Subconical, longer and more strongly tapering in male. Male: T6 bare, well­developed; S2 and S3 unmodified; S4 unmodified or weakly sclerotized posteriorly; S5 mostly membranous, divided medially into weakly sclerotized longitudinal bands fusing with S6 posteriorly; S6 sclerotized along anterior margin, Y­shaped, fused to T6 posterolaterally, with base extending anteromedially into S5; segment 7 forming welldeveloped peduncle; S8 teardrop­shaped, setose. Hypopygium ( Fig. 21 A–C) large. Epandrium subrectangular to ovoid, longer than high; foramen postioned anterolaterally, wellseparated from base of cerci; basiventral epandrial lobe weakly developed, with weak basiventral epandrial seta; apicoventral epandrial lobe elongate with rounded or subtriangular apex bearing three setae. Surstylus bilobed. Ventral lobe subquadrate with 1 dorsobasal seta, 1 mid­ventral seta, 1 thickened medial seta, and subtriangular apicoventral extention bearing thick apical seta. Dorsal lobe slightly longer than ventral lobe, broad with acute apex, 1 strong dorsal seta. Postgonite with anteroventral portion weakly sclerotized; posterodorsal portion well­developed, with preapical lateroventral lobes ( Fig. 21 B). Proctiger brushes absent. Cercus subtriangular with strong marginal setae. Hypandrium narrow, tapered distally, as long as or slightly longer than apicoventral epandrial lobe, fused to epandrium laterally near basiventral epandrial lobe ( Fig. 21 A,C); hypandrial apodeme present, well­developed, hypandrial arms connected to hypandrium. Sperm pump cylindrical; ejaculatory apodeme well­developed, elongate and laterally flattened; basal sclerite of sperm pump heavily sclerotized, V­shaped in dorsal view. Phallus long and slen­ der with dentiform process in apical portion (present in P. zhongdianus and P. orientalis Yang, Saigusa & Masunaga ). Female ( Fig. 21 D,E): T6, T7, S6 and S7 undivided; T8 and S8 divided medially; tergite and sternite weakly fused anterolaterally. T10 divided medially into hemitergites each bearing 4 spines along outer margin and a single inner medial spine, spines rounded and flattened apically. Upper lobe of cercus with long apical seta.

Geographical Distribution. This genus includes three species, all of which are known only from Oriental China (Yunnan) ( Yang 1998a; Yang et al. 2001).

Phylogenetic Relationships. Parahercostomus appears to be closely related to Grichanov’s (1999a) Afrotropical Hercostomus species group 1.

Remarks. Although not mentioned by Yang et al. (2001), the loss of the presutural seta is an autapomorphy of Parahercostomus . Yang (pers. comm.) has confirmed that this seta is absent in P. triseta .

Material Examined. Parahercostomus orientalis Yang, Saigusa & Masunaga , [OR]: 2ɗ paratypes, 1Ψ paratype ( SKU); 1ɗ paratype, 1Ψ paratype (LEM); Parahercostomus zhongdianus (Yang) , [OR]: 2ɗ paratypes, 2Ψ paratypes ( SKU); 1ɗ paratype, 1Ψ paratype (LEM).

Figures

FIGURE 21. Parahercostomus zhongdianus: (A) Male genitalia, left lateral view (external); (B) Male genitalia, left lateral view (internal); (C) Male genitalia, ventral view (postgonite, surstylus and cerci not shown); (D) Female genitalia, dorsal view; (E) Female genitalia, left lateral view.