Crossopalpus Bigot, 1857

Grootaert, Patrick & Shamshev, Igor V., 2012, The fast-running flies (Diptera, Hybotidae, Tachydromiinae) of Singapore and adjacent regions, European Journal of Taxonomy 5, pp. 1-162 : 47-48

Genus Crossopalpus Bigot, 1857

Crossopalpus Bigot, 1857: 557 , 563. Type-species: Platypalpus ambiguus Macquart, 1827 , by monotypy [=? Crossopalpus flexuosus (Loew, 1840) ].

Eudrapetis Melander, 1918: 187 (as subgenus of Drapetis ). Type-species: Drapetis spectabilis Melander, 1902 , by original designation.

Therinopsis Vimmer, 1939: 64 . Type-species: Therinopsis richardsi Vimmer, 1939 , by monotypy [= Crossopalpus humilis (Frey, 1913) ].

Recognition

The genus Crossopalpus can be distinguished from other genera of the Drapetini by the following combination of characters: head close-set upon thorax, gena very broad; anterior ocellars reduced, posterior ocellars long; antennae upturned, pedicel usually with very long seta beneath, postpedicel more or less rounded ventrally; wing with Rs very short, shorter than crossvein bm-cu; abdominal tergites without squamiform setae.

Diagnosis

Small to medium-sized (1.5-2.5 mm) largely shining black robust flies. Head closely set upon thorax. Frons with sides divergent above. Face very narrow. One pair of vertical bristles. Ocellar tubercle with anterior ocellars reduced, posterior ocellars long. Antennae upturned, pedicel usually with single very long seta beneath, postpedicel more or less rounded ventrally; stylus arising apically, arista-like, long. Gena greatly produced. Palpus varying in size and setation; lacking sensory pit. Thorax largely shining. Postpronotal bristle not prominent. Mesonotal bristles very prominent but usually evenly covered with hair-like setulae; no setae between mid and hind coxae; anepisternum (= mesopleuron) bare. Legs short, robust, hind tibia often with prominent bristles and apical projection. Wings normally developed,

usually hyaline; Rs short, originating near midway of R 1; R 1 meeting costa at middle of wing; R 2+3 complete, meeting costa beyond middle of wing; R 4+5 and M 1+2 more or less parallel or convergent near wing margin; A 1 absent; crossvein CuA 2 absent; crossvein bm-cu somewhat oblique or transverse; cell br shorter than cell bm. Abdomen with some tergites modified or unmodified; squamiform setae absent;

gland-like intersegmental structures absent or present. Terminalia with epandrium completely divided or undivided; left epandrial lamella fused to hypandrium; left surstylus differentiated from epandrial lamella,

divided; right surstylus differentiated from epandrial lamella; cerci separated; epiproct unmodified;

hypandrium setose subapically or bare; phallus short; two rod-shaped apodemes (i.e. ejaculatory and ventral apodemes) present. Female similar to male or lacking abdominal modifications; terminalia rather shortened; tergite 8 separated from sternite 8; cercus elongate ovate.

Remarks

Including a new species described in this paper, the world fauna of Crossopalpus includes 83 species, 15 of them are recorded from the Oriental Region. Formally, Crossopalpus is recorded here for the first time from Singapore but in the key given below we also include two species that we believe to likely occur here.

In the Palaearctic Region the species of Crossopalpus inhabit different biotopes occurring in heaps of cut sedge and litter, under dead leaves, in grass tufts, on human or animal dung, on trees and bushes, and on the sandy or swampy banks of lakes and rivers ( Chvála 1975). Working in Viet Nam, Tran et al. (2006) found that C. hirsutipes Collin is an important predator of the leafminer Liriomyza sativae Blanchard ( Diptera : Agromyzidae ) in greenhouses.

Key to species of Crossopalpus from Singapore

1. Abdominal tergite 3 with thickened hind margin. Hind tibia with numerous outstanding pale hair-like setae (2.0-3.0 times as long as tibia is thick), lacking prominent bristles (South India; Cambodia; Viet Nam; Thailand)…………………....................................... C. hirsutipes Collin, 1960

– Abdominal tergite 3 unmodified. Hind tibia with short setulae, bearing strong bristles subapically..2

2. Hind tibia with 2 black, short, closely set, subapical bristles. Scutum at least with 3 pairs of moderately long prescutellar dorsocentral bristles ( Philippines).......... C. exul (Osten-Saken, 1882)

– Hind tibia with 4 bristles anteriorly near apex (2 black and spine-like). Scutum with 1 pair of long prescutellar dorsocentral bristles ( Singapore)............................................ C. temasek sp. nov.