Cheiromyia Dyte

SCOTT E. BROOKS, 2005, Systematics and phylogeny of Dolichopodinae (Diptera: Dolichopodidae), Zootaxa 857, pp. 1-158 : 43-46

Genus Cheiromyia Dyte

( Fig. 8 A–C)

Cheirocerus Parent, 1930a: 13 . Type species: Cheirocerus palmaticornis Parent [Neotropical], by monotypy. Preoccupied by Cheirocerus Eigenmann, 1917 .

Cheiromyia Dyte, 1980: 223 . Type species: Cheirocerus palmaticornis Parent , automatic. N. name for Cheirocerus Parent, 1930a .

New Combination. The following new combination is hereby established: Cheiromyia maculipennis ( Van Duzee, 1934) comb. nov. ( Sarcionus ).

Recognition. Two of the three described species, C. palmaticornis and C. pennaticornis can be easily recognized by the distinctive antennae with several slender pubescent projections on the outer surface of the first flagellomere. Cheiromyia maculipennis lacks projections on the first flagellomere and can be identified by characters given in the key. All species share a characteristic sperm pump that is folded back on itself.

Description (male). Head: Usually slightly broader than high, occasionally distinctly broader than high (e.g., C. pennaticornis ). Occiput convex medially, sometimes slightly concave behind postoculars (e.g., C. pennaticornis ). Vertex distinctly excavated, 1 pair of strong vertical setae, stronger than postverticals. Frons about 2– 3 x wider than high, sides subparallel to convergent anteriorly. Face very narrow, with sides strongly converging below (e.g., C. maculipennis ) to quite broad (e.g., C. pennaticornis ) with sides subparallel; clypeus flat, lower margin straight, ending well above lower eye margin. Palp small, with weak to somewhat elongate setae on outer surface (e.g., Cheiromyia sp. 1), with or without distinct apical seta. Antenna: Scape short, subconical, with weak to well­developed acute process medioventrally and ventrally; pedicel unmodified and short (e.g., C. maculipennis ) to strongly flattened (e.g., C. pennaticornis ); first flagellomere variable in shape: subtriangular (e.g., C. maculipennis ), ovoid basally with long, narrow, tapering apex (e.g., C. palmaticornis ), or greatly elongated and narrowly triangular (e.g., C. pennaticornis ), outer surface usually with series of 3–9 slender pubescent projections, projections sometimes branched, absent in C. maculipennis ; arista dorsal, 2­segmented, distinctly pubescent, occasionally plumose (e.g., C. pennaticornis ). Lowermost postocular seta sometimes stronger. Postvertical setae slightly to distinctly stronger than uppermost pair of postoculars.

Thorax: Acrostichals biserial; usually 6 distinct dorsocentrals, anteriormost dorsocentral sometimes small to indistinct (e.g., C. maculipennis ), aligned; 1 outer posthumeral, 1 weaker inner posthumeral; 2 notopleurals; 1 presutural; 1 sutural; 2 supraalars; 1 postalar. Upper part of propleuron with cluster of weak hairs; lower part of propleuron with 1 strong prothoracic seta and weak hairs; pleural surface in front of posterior spiracle bare; metepisternum with a row of 2–3 fine hairs. Scutellum with 1 strong inner seta and 1 small outer seta on lateral margin.

Legs: Pulvilli developed normally on all legs, small but distinct. Foreleg: Femur usually with distinct posterior preapical seta, or a series of 2–3 progressively longer setae; tibia sometimes thickened (e.g., Cheiromyia sp. 1); tarsus sometimes with distinct pile ventrally and enlarged claws (e.g., C. pennaticornis ). Midleg: Femur with 1 anterior or anterodorsal preapical seta; tibia occasionally with 1 fine apicoventral seta (e.g., C. maculipennis ); basitarsus with distinct to strong basiventral seta, tarsomeres 2–3 weakly flattened on medial surface and silvery in C. maculipennis . Hindleg: Coxa with strong lateral seta slightly to distinctly below middle; femur with 1 anterodorsal preapical seta; tibia lacking posteroapical process; basitarsus distinctly shorter than second tarsomere, with distinct basiventral seta and 1–3 weaker ventral setae, with small hook­like process posterobasally.

Wing: Hyaline or brownish, occasionally with apical third brown (e.g., C. maculipennis ). R2+3 weakly sinuous basally, straight in distal section; R4+5 straight, with or without weak posterior curve in distal section; distal section of M beyond crossvein dm­cu usually with strong anterior bend near middle, bend occasionally weak (e.g., C. maculipennis ), ending before wing apex; crossvein dm­cu subqual to or longer than distal section of CuA1.

Abdomen: Subconical. T6 bare; S2 unmodifed; S3 unmodified to emarginate and membranous posteromedially; S4 strongly emarginate and membranous posteromedially, sometimes divided; S5 mainly membranous, sometimes with a pair of textured membranous lobes basally (e.g., C. maculipennis , C. palmaticornis ); S6 mainly membranous, weakly sclerotized along anterior margin; segment 7 forming well­developed peduncle; S8 ovoid to teardrop­shaped, setose. Hypopygium ( Fig. 8 A–C): Epandrium subrectangular in lateral view, about 1.7–2.0 x longer than high; foramen positioned anterolaterally, wellseparated from base of cerci; basiventral epandrial lobe usually not developed with basiventral epandrial seta arising on infolded ventral epandrial margin, small lobe occasionally present with basiventral epandrial seta arising on medial surface (e.g., C. pennaticornis ); apicoventral epandrial lobe well­developed and projecting ventrally, sometimes distinctly anteroposteriorly flattened (e.g., C. maculipennis ), with 2 preapical to apical setae, setae often long and fine, C. palmaticornis with elongate narrow projection arising from medial surface of left lobe ( Fig. 8 A,B). Surstylus bilobed. Ventral and dorsal lobes more or less digitiform and subequal in length; dorsal lobe often with rounded preapical projection. Postgonite with anteroventral portion weakly sclerotized; posterodorsal portion well­developed, digitiform. Proctiger brushes absent. Cercus usually subtriangular or ovoid with weak marginal setae, cercus of C. palmaticornis very large, triangular, with strong setae on apical margin ( Fig. 8 A). Hypandrium long, trough­like (e.g., C. palmaticornis , Fig. 8 A,B) or bifurcate (e.g., C. maculipennis ), with membranous connection to epandrium basiventrally, free laterally; hypandrial apodeme absent; hypandrial arms connected to hypandrium. Sperm pump large, tubular and folded back on itself ( Fig. 8 C); ejaculatory apodeme usually well­developed, laterally flattened; basal sclerite of sperm pump wide, more or less straight in dorsal view, occasionally positioned apicodorsally on sperm pump. Phallus slightly to distinctly thickened, sometimes flared preapically with narrow apex, apex occasionally bifurcate (e.g., C. maculipennis ).

Female unknown.

Geographical Distribution. This genus is known only from the Neotropical Region including Guyana, Brazil, Ecuador and Bolivia.

Phylogenetic Relationships. Cheiromyia is part of the clade including Paraclius , Stenopygium , Pelastoneurus , Platyopsis and Tachytrechus . The discovery of females may help to elucidate the position of this genus within this clade (see “ Tachytrechus genusgroup” section above).

Remarks. The two BMNH specimens determined by H. Oldroyd and J.C. Deeming as C. palmaticornis belong to an undescribed species (here referred to as Cheiromyia sp. 1) with a thickened fore tibia and shortened tarsomere 2 on the foreleg.

The holotype and paratype of C. maculipennis may represent two similar species that differ in the shape of the first antennal flagellomere, hypandrium and phallus; however, more specimens are required to determine if these differences are discrete or part of a continuum of variation. Curran (in Van Duzee 1934) noted a possible female of C. maculipennis in the AMNH (not examined).

Material Examined. Cheiromyia maculipennis (Van Duzee) , [NT]: ɗ holotype ( AMNH); ɗ paratype ( CAS); Cheiromyia palmaticornis Parent , [NT]: ɗ holotype ( NMW); 6ɗ ( USNM); Cheiromyia pennaticornus Parent , [NT]: ɗ holotype ( SMTD); Cheiromyia sp. 1, [NT]: 2ɗ ( BMNH).

Figures

FIGURE 8. Cheiromyia palmaticornis: (A) Male genitalia, left lateral view (external); (B) Male genitalia, ventral view (postgonite, surstylus and cerci not shown); (C) Male genitalia, left lateral view (internal).