Brachystoma vesiculosum ( Fabricius, 1794 )

Brachystoma vesiculosum ( Fabricius, 1794) View in CoL

( Figs 1 View FIG ; 2 View FIG ; 3A, B View FIG ; 4 View FIG ; 5 View FIG )

Syrphus vesiculosus Fabricius, 1794: 299 View in CoL .

Brachystoma flavicolle Mik, 1887: 103 View in CoL .

Brachystoma obsculipes Saigusa, 1963: 167 (spelling error for B. obscuripes View in CoL ).

MATERIAL EXAMINED. — France • 1♂; Vidauban , Bois de Bouis (83); 43°23’53”N, 6°28’3”E; 28.III-7.V.2014; Pierre-Alexis Rault; malaise trap 1; MNHN GoogleMaps • 1♂; Vidauban , Bois de Bouis (83); 43°22’56”N, 6°29’34”E; 28.III.-28.V.2014; Pierre-Alexis Rault; malaise trap 2; voucher code: EMPB1; GenBank COI gene: PP501165 ; MNHN-ED-ED11761 GoogleMaps • 1♀; same data as for preceding; voucher code: EMPB4; GenBank COI gene: PP501166 ; MNHN-ED-ED11762 GoogleMaps • 3♂, 2♀; same data as for preceding; MNHN GoogleMaps .

TYPE MATERIAL AND LOCALITY. — Fabricius described Syrphus vesiculosus twice, on specimens that are all present in the NHMD. The original description was published in 1794, based on a not-specified number of specimens all collected in Italy.Today these specimens are represented in the Fabricius collection by a single wing and a small piece of thorax attached to a pin ( Fig. 2 View FIG ). The second description was presented in 1805 and based on two well-preserved specimens that are true syrphids and for which Thompson proposed the name Copestylum neotropicum ( Thompson 1976) .

The single wing that remains from the specimens used for the original description has the typical venation of the genus Brachystoma and is therefore considered to belong to B. vesiculosum . Consequently this specimen is herewith designated as lectotype of Syrphus vesiculosus Fabricius (valid name Brachystoma vesiculosum ) and labelled accordingly to fix and stabilize the current concept of the name ( Fig. 2 View FIG ).

DIAGNOSIS. — Species blackish to brownish in ground color. Frons, face and thorax blackish with sparse grey pruinosity more or less visible depending on the orientation of the specimen. Coxae brownish to yellowish, femora yellow to brownish dorsally, tibiae and tarsi entirely blackish. Eyes dichoptic, antennae with a long stylus. Female postabdomen considerably modified, with tergite 7 enlarged, globose, developed laterally, enclosing segments 8 to 10 and cercus.

DISTRIBUTION ( Fig. 8 View FIG ). — Austria, Croatia, France (mainland), Germany, Italy (mainland), Macedonia, Poland, Romania, Slovakia, Switzerland.

DESCRIPTION

Male ( Figs 1 View FIG ; 3A View FIG ; 4 View FIG )

Head. Occiput black with a row of rather strong black postocular setae. Ocellar triangle black with orange-brown ocelli and a pair of fine setae. Antennae blackish; scape and pedicel of same length with a few fine, short setae, postpedicel a little longer than pedicel, stylus four times the postpedicel length. Frons and face blackish, the former a little broader than the latter. Labrum blackish, three times shorter than head height; labium short, very thick, spatula-like; palpus yellowish, short, rather thick, directed downwards, with yellowish fine, short hairs. Eyes dichoptic, all ommatidia of equal size.

Thorax. Black with sparse grey pruinosity on mesopleuron. Antepronotum with a pair of short, fine black setae. Postpronotum blackish to brownish anteriorly, without seta. One strong, long notopleural and postalar, scutellum with one pair of strong, long subapical setae, additional pair of fine, short apicals and moderatly long basal not always present or visible. All other setae inconspicuous, whitish, including one row of dorsocentrals. Acrostichals absent.

Legs. Fore coxa mainly brownish to yellowish ventrally, mid coxa mainly yellowish to brownish dorsally, hind coxa yellowish, all coxae covered with whitish vestiture, visible depending on the orientation, with 2-4 strong, long black setae. All trochanters brownish to yellowish. All femora yellow to more or less brownish dorsally; fore femur ventrally covered with minute spines, with two distinct anterolateral and anteroventral setae in apical half, 4-5 distinct posteroventral setae; mid femur ventrally covered with minute spines except basally, with anterolateral, antero- and posteroventral rows of 6-7 strong, long setae; hind femur ventrally covered with minute spines, with two distinct anterolateral setae apically, antero- and posteroventral rows of less than 10 strong, more or less long setae. All tibiae dark brown to black, with a regular ventral row of minute spines, one distinct dorsal seta at base; hind tibia somewhat thickened apically, ventrally covered with minute ventral whitish vestiture apically, distinct apical comb. All tarsi black without distinct setae.

Wings. Size 6-6.5 mm. Brownish with dark brown stigma, all veins well sclerotized, C and Sc complete, radial fork R4 +5 widely open, bell-like, A1 abbreviated, anal lobe not developed. Halter yellow.

Abdomen. Brownish in ground color with only fine, short whitish hairs, tergites 3-5 somewhat yellowish along anterior margin, tergite 8 reduced to simple, thin dorsal ring, sternite 8 well developed, lengthened posterodorsally.

Hypopygium. Cercus wide basally, thin in apical half with a slight pre-apical bulge; fine, short dorsal hairs. Lateral epandrial lamellae developed dorsally and epandrium nearly unpaired, posterior part lengthened and rounded apically with numerous strong, long black ventral setae, fine, shorter whitish dorsal setae. Hypandrium well developed ventrally with a few fine posterior setae. Postgonite present, pointed apically. Phallus long, thin, bent anteriorly forming a characteristic loop.

Female ( Figs 3B View FIG ; 5 View FIG )

Similar to male except for the following characters: postabdomen modified with tergite 7 enlarged, globose, developed laterally, enclosing segments 8 and 10 and cerci, but remaining open ventrally; sternite 7 lengthened posteriorly; tergite 8 well developed, well sclerotized anteriorly, with many dorsal minute spines; sternite 8 lengthened posteriorly, with distinct setae on the dorsal margin and a few shorter setae apically; tergite 10 with about 10 characteristic acanthophorites posterodorsally on each side; sternite 10 rather membranous with a few fine setae; cercus not horizontal but somewhat upright and bent anteriorly, well sclerotized apically.

DNA BARCODE

A 658 base-pair fragment of the COI gene was amplified and sequenced from two specimens (EMPB1, male, and EMPB4, female) Both sequences match 100% but the divergence rate with B. obscuripes is about 3%.