Sybistroma Meigen

SCOTT E. BROOKS, 2005, Systematics and phylogeny of Dolichopodinae (Diptera: Dolichopodidae), Zootaxa 857, pp. 1-158 : 112-120

publication ID	https://doi.org/ 10.5281/zenodo.170753
DOI	https://doi.org/10.5281/zenodo.6266958
persistent identifier	https://treatment.plazi.org/id/D40A8783-FFD3-2E00-7350-F94DFED7DD3B
treatment provided by	Plazi
scientific name	Sybistroma Meigen
status

Treatment

Genus Sybistroma Meigen View in CoL View at ENA

( Figs. 30 View FIGURE 30 A–E, 31A–E, 32A–E) Sybistroma Meigen, 1824: 71 : Type species: Dolichopus discipes Germar (as “Ahrens”) [Palaearctic], designation by Westwood, 1840: 135 (see “Remarks”).

Hypophyllus Haliday, 1832: 359 : Type species Dolichopus obscurellus Fallén View in CoL [Palaearctic], by monotypy (see “Remarks”).

Ludovicius Rondani, 1843: 43 . Type species: Ludovicius impar Rondani View in CoL [Palaearctic], by monotypy. syn. nov.

Nodicornis Rondani, 1843: 46 . Type species: Nodicornis View in CoL wiedemanni Rondani [Palaearctic], by monotypy [= Sybistroma nodicornis Wiedemann in Meigen, 1824: 72 View in CoL ]. syn. nov.

Haltericerus Rondani, 1856: 143 . Type species: Ludovicius impar Rondani View in CoL [Palaearctic], by original designation. syn. nov.

Nemospathus Bigot, 1859: 215 , 228. Type species: Sybistroma dufouri Macquart [Palaearctic], by monotypy. syn. nov.

Osodostylus: Bigot, 1859: 215, incorrect original spelling of Ozodostylus Bigot, 1859 by revision of Evenhuis and Pont (2004: 43).

Ozodostylus Bigot, 1859: 225. Type species: Sybistroma nodicornis Wiedemann in Meigen (as “Macq.”) [Palaearctic], by original designation. syn. nov.

Dasyarthrus Mik, 1878: 5 . Type species: Gymnopternus inornatus Loew View in CoL [Palaearctic], by original designation. syn. nov.

Spathitarsis Bigot, 1888a: xxiv [1888c: xxiv]. Type species: Dolichopus discipes Germar View in CoL (as “Ahrens”) [Palaearctic], by original designation.

Hyppophyllus, incorrect subsequent spelling by Bigot, 1890: 276.

Hyphyllus , incorrect subsequent spelling by Becker, 1917: 255

Hemospathus, incorrect subsequent spelling by Bigot, 1888a: xxiv, 1888c: xxiv

Ludovicus , incorrect subsequent spelling by Bigot, 1859: 218

Paecilobothrus incorrect subsequent spelling by Bigot, 1890: 294

Spatiotarsus incorrect subsequent spelling by Bigot, 1890: 263

Recognition. Most males of Sybistroma can be distinguished by the following combination of characters: antenna usually modified, with enlarged scape, reduced pedicel, arista 1segmented and usually with one or more lamellae; wing with weak sinuous anterior bend before middle; hypopygium usually with basiventral epandrial lobes elongate and digitiform with pointed or frayed knoblike tip, shifted ventrally and lying beside hypandrium. Males lacking modified antennae can be distinguished by the possession of greatly elongated and setose apicoventral epandrial lobes. Females cannot readily be distinguished from some species currently placed in Hercostomus .

Description. Head: Sometimes distinctly broader than high in male (e.g., S. dufouri ). Vertex more or less flat to weakly excavated, 1 pair of strong vertical setae, stronger than postverticals. Frons about 2– 3 x wider than high, sides weakly convergent anteriorly, male occasionally with dense tuft of velvety hairs between antennal socket and eye margin near fronsface boundary (e.g., S. nodicornis ). Face very narrow to broad in male, with sides converging below, broad in female, sides subparallel to weakly converging below; clypeus relatively narrow and flat to weakly produced in male, broad and often strongly produced in female, lower margin straight to weakly emarginate, not reaching lower eye margin. Palp usually small, ovoid, occasionally enlarged and flattened (e.g., S. dorsalis ) with fine setae on outer surface, distinct apical seta present or absent. Antenna often modified in male, occasionally inserted just slightly above middle of head in male; scape of male usually slightly to greatly swollen and semiglobular (e.g., S. impar ), sometimes unmodified and subconical (e.g., S. obscurellum ), medioventral process usually absent or indistinct, sometimes weakly developed; scape of female short, subconical, with welldeveloped to indistinct medioventral process; pedicel short, often strongly reduced in male (e.g., S. impar ); first flagellomere of male variable in size and shape, short and rounded apically (e.g., S. spectabilis ) to greatly elongated and acute apically (e.g., S. nodicornis ); first flagellomere of female short, usually about as long as wide, rounded or pointed apically; arista of male dorsobasal to apical, 1 or 2segmented, short to greatly elongated, often with apical lamella, occasionally also with 1–2 medial lamellae, basal segment occasionally elongate (e.g., S. discipes ), distal segment weakly pubescent to glabrous; arista of female dorsal to subapical, 2segmented, distal segment weakly pubescent. Lower postocular setae sometimes weaker. Postvertical setae subequal to distinctly stronger than uppermost pair of postoculars.

Thorax: Acrostichals usually biserial, occasionally extending to base of scutellum (e.g., S. nodicornis ), sometimes uniserial (e.g., S. biniger ), reduced or absent (e.g., S. flavus ); 6 dorsocentrals, fifth pair slightly to strongly offset medially; 1 strong outer posthumeral, 1 weak to indistinct inner posthumeral; 2 notopleurals; 1 presutural; 1 sutural; 2 supraalars; 1 postalar. Upper and lower part of propleuron with fine hairs; lower part of propleuron with 1 strong prothoracic seta; pleural surface in front of posterior spiracle bare; metepisternum usually with 1 or more fine hairs in a cluster or row, occasionally absent (e.g., S. inornatus ); katepisternum sometimes with sparse fine hairs (e.g., S. impar , S. eucerus , S. dufouri ). Scutellum with 1 strong inner seta and 1 small outer seta on lateral margin, dorsum and posterior margin often with fine setae, sometimes dense (e.g., S. nodicornis ).

Legs: Pulvilli usually developed normally on all legs, occasionally somewhat reduced on foreleg of males with enlarged fifth tarsomere (e.g., S. discipes ). Foreleg: Femur usually with distinct posteroventral preapical seta; tibia occasionally with distinct anterodorsal comblike row of strong setae (e.g., S. flavus ); tarsus of male sometimes modified (e.g., S. crinipes Staeger , S. discipes , S. eucerus ). Midleg: Coxa of male occasionally with elongate, curved marginal setae (e.g., S. eucerus ); femur with 1 anterior preapical seta, occasionally with weakly differentiated to distinct posterior preapical in addition to terminal posteroventral preapical seta that is usually present (e.g., S. lorifer , some specimens of S. impar ), male sometimes with 2–3 long basiventral setae (e.g., S. flavus ), or with row of elongate ventral setae (e.g., S. eucerus ); tarsus of male occasionally modified, with distal segments flattened (e.g., S. nodicornis ). Hindleg: Coxa with strong lateral seta near or slightly above middle; femur with 1 anterodorsal preapical seta, male occasionally with 1 or more long ventral setae in basal part (e.g., S. miricornis ), male sometimes with welldeveloped setae dorsobasally (e.g., S. nodicornis ); tibia of male with or without weak dentiform posteroapical process; basitarsus usually shorter than second tarsomere, occasionally subequal, often with a few ventral setae, male with or without weak dentiform or hooklike process posterobasally.

Wing: Brownish to grayish. R2+3 relatively straight; R4+5 with distinct posterior curve in distal section; distal section of M beyond crossvein dmcu with weak sinuous anterior bend before middle, ending near to distinctly before wing apex; R4+5 and M weakly to distinctly convergent, occasionally subparallel; crossvein dmcu distinctly shorter than distal section of CuA1.

Abdomen: Subconical, sometimes elongate and slender in male, with tergites long. Male: T5 sometimes with elongate setae on posterior margin; T6 bare; S2 and S3 unmodified to weakly sclerotized and partially membranous; S4 emarginate posteromedially to mainly membranous; S5 mainly membranous, often with weakly sclerotized longitudinal bands; S6 mainly membranous, weakly sclerotized along anterior margin; segment 7 forming welldeveloped peduncle; S8 subtriangular or heartshaped to subquadrate, setose. Hypopygium ( Figs. 30 View FIGURE 30 A–C, 31A–C, 32A–C) large. Epandrium variable in shape, about 1.5–3.0 x longer than high, often deeply cleft dorsally with cerci arising preapically ( Figs. 30 View FIGURE 30 A, 31A); foramen slightly to distinctly dorsolateral, close to base of cerci (e.g., S. obscurellum , Fig. 30 View FIGURE 30 A) or wellseparated from base of cerci (e.g., S. nodicornis , Fig. 32 View FIGURE 32 A); basiventral epandrial lobes shifted ventrally and lying beside hypandrium, right and left lobes usually elongate, digitiform and symmetrical, occasionally asymmetrical, basiventral epandrial seta apical usually thickened, knoblike with pointed or frayed tip ( Figs. 31 View FIGURE 31 A, 32A), occasionally unmodified ( Fig. 30 View FIGURE 30 B); apicoventral epandrial lobe variable, weakly to strongly developed, with or without setae, lobe sometimes greatly elongated, with elongate and/or modified setae (e.g., S. obscurellum , S. impar , Figs. 30 View FIGURE 30 A,C, 31A,C). Surstylus bilobed. Ventral and dorsal lobe more or less digitiform and similar in size, sometimes extremely elongate and slender (e.g., S. obscurellum , S. impar , Figs. 30 View FIGURE 30 B, 31B), dorsal lobe occasionally with frayed seta (e.g., S. nodicornis , Fig. 32 View FIGURE 32 B). Postgonite with anteroventral portion weakly to moderately sclerotized, sometimes distinctly flattened laterally; posterodorsal portion welldeveloped, slightly to strongly upturned, sometimes elongate (e.g., S. obscurellum , S. impar , Figs. 30 View FIGURE 30 B, 31B), usually with weak lateral projection in basal portion, projection occasionally welldeveloped and subapical (e.g., S. nodicornis ), extreme base occasionally with weak, sometimes bifurcate, projection (e.g., S. discipes , S. eucerus ). Proctiger brushes absent. Cercus variable in shape, subrectangular to subtriangular or ovoid, sometimes with distinct notch along apical margin, often with 1 or more thick, modified setae (e.g., S. obscurellum , S. impar , Figs. 30 View FIGURE 30 A, 31A). Hypandrium variable, troughlike (e.g., S. obscurellum , Fig. 30 View FIGURE 30 C), to asymmetrical, sometimes partially membranous and/or with dorsal projections (e.g., S. nodicornis , Fig. 32 View FIGURE 32 B,C), hypandrium laterally flanked by basiventral epandrial lobes and fused with lobes basally; hypandrial apodeme present, welldeveloped; hypandrial arms connected to hypandrium. Sperm pump small, rounded to subconical; ejaculatory apodeme usually short and rodlike, often upturned, apex occasionally weakly flattened laterally; basal sclerite of sperm pump weakly developed, widening apically, subtriangular to Vshaped in dorsal view. Phallus long, slender and curved (e.g., S. obscurellum , Fig. 30 View FIGURE 30 B) to relatively short and straight, with distinct articulation basally with sperm pump (e.g., S. nodicornis , S. impar , Figs. 31 View FIGURE 31 B, 32B). Female ( Figs. 30 View FIGURE 30 D,E, 31D,E, 32D,E): T6, T7, S6 and S7 undivided; T8 divided medially, S8 divided medially or undivided, tergite and sternite not fused anterolaterally; T10 divided medially into hemitergites each bearing 3–5 spines, apex of spines rounded and flattened. Upper lobe of cercus usually with long apical seta.

Geographical Distribution. Sybistroma , as newly defined above (i.e. including species of Ludovicius and Nodicornis ), occurs in the Palaearctic (Europe and North Africa to China), Oriental China (Yunnan) and in the Afrotropical realm.

Phylogenetic Relationships. Sybistroma is most closely related to the Hercostomus longiventris lineage based primarily on the position of the basiventral epandrial lobes that are shifted ventrally and laterally flanking the hypandrium (character 63:1).

Remarks. As noted by Chandler (1998: Note 3), Hypophyllus Haliday, 1932 is a junior synonym of Sybistroma Meigen, 1824 because of the designation of Dolichopus discipes Germar, 1821 as the type species of Sybistroma by Westwood (1840: 135). Dolichopus discipes Germar, 1822 is considered to be congeneric with Dolichopus obscurellus Fallén, 1823 , the type species of Hypophyllus .

Yang (1996c) described Hypophyllus sinensis Yang from Palaearctic China; however, this species is not congeneric with Sybistroma and clearly belongs to the clade including Poecilobothrus , Parahercostomus and Grichanov’s (1999a) Afrotropical Hercostomus species group 1, based on the possession of preapical dorsolateral lobes on the postogonite. In particular, this species appears to be closely related to Grichanov’s (1999a) Afrotropical Hercostomus species group 1 based on the modified hind tarsus of males; however, until a more extensive phylogenetic analysis of this lineage is completed this species will remain unplaced. For the present I have listed it below as “ Hypophyllus ” sinensis indicating the problematic generic assignment.

Parent (1938) noted that the arista of males of S. miricornis is 2segmented; however, a more detailed examination (including a slide mount of the arista under a compound microscope at high power) indicates that the arista is actually 1segmented.

Material Examined. Sybistroma binodicornis Stackelberg , [PA]: 1ɗ ( USNM); Sybistroma crinipes (Staeger) , [PA]: 3ɗ, 5Ψ (LEM); Sybistroma discipes (Germar) , [PA]: 2ɗ ( CNC); 1ɗ, 1Ψ ( BMNH); Sybistroma dufouri Macquart , [PA]: 2ɗ, 1Ψ ( CNC); Sybistroma eucerus (Loew) , [PA]: 2ɗ ( DEI); Sybistroma flavus (Yang) , [PA]: 1ɗ (LEM); Sybistroma impar (Rondani) , [PA]: 1ɗ, 2Ψ ( DEI); 1ɗ ( BMNH); Sybistroma inornatus (Loew) , [PA]: 2ɗ, 2Ψ ( USNM); 1ɗ, 1Ψ ( CNC); Sybistroma lorifer (Mik) , [PA]: 1ɗ, 1Ψ ( ISNB); Sybistroma maerens Loew , [PA]: 2ɗ, 2Ψ ( DEI); Sybistroma miricornis (Parent) , [PA]: 2ɗ syntypes, 2Ψ syntypes ( DEI); 2ɗ syntypes, 2Ψ syntypes ( MNHN); Sybistroma nodicornis Wiedemann , [PA]: 2ɗ, 2Ψ (LEM); 1ɗ ( BMNH); 1ɗ ( CNC); Sybistroma obscurellum (Fallén) , [PA]: 13ɗ, 4Ψ (LEM); 4ɗ, 2Ψ ( CNC); Sybistroma setosa Schiner , [PA]: 2ɗ, 1Ψ ( DEI); Sybistroma spectabilis (Parent) , [PA]: 1ɗ ( MNHN); Sybistroma sphenopterum (Loew) , [PA]: 1ɗ (LEM); “ Hypophyllus ” sinensis Yang , [PA]: 1ɗ paratype, 1Ψ paratype (LEM).

USNM	Smithsonian Institution, National Museum of Natural History
CNC	Canadian National Collection of Insects, Arachnids, and Nematodes
DEI	Senckenberg Deutsches Entomologisches Institut
MNHN	Museum National d'Histoire Naturelle

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Taxonomy

Kingdom	Animalia
Phylum	Arthropoda
Class	Insecta
Order	Diptera
Family	Dolichopodidae
SubFamily	Dolichopodinae

Kingdom	Animalia
Phylum	Arthropoda
Class	Insecta
Order	Diptera
Family	Dolichopodidae
SubFamily	Dolichopodinae