Tolmerus calceatus ( Meigen, 1820 ), 2018

Broek, Reinoud Van Den, Smit, John T., Bree, Elias De & Beentjes, Kevin, 2018, Tolmerus calceatus (Meigen) confirmed as a valid species separate from Tolmerus atricapillus (Fallén) (Diptera: Asilidae), Zootaxa 4508 (2), pp. 249-258 : 252-254

Tolmerus calceatus ( Meigen, 1820) stat. rev.

(figure 2 & plate 1 )

Asilus calceatus, Meigen, 1820

Machimus atricapillus calceatus ( Meigen, 1820) ; Engel (1930); Tomasovic (1993, 1995)

Tolmerus atricapillus ( Fallén, 1814) ; Lehr (1988)

Type: ♀, “Europe” ( MNHN)

Material examined. Belgium 6♂ 4♀ Saint Hubert , 7.viii.1925, 9.vii.1925, 18.viii.1929, 19.viii.1929, leg. Goetghebuer (KBIN); France 2♂ St. Lunaire , 2.viii.1905, leg. Villeneuve ( KBIN) ; 1♂ Maisons L’aff [sic], ix.1907, leg. Villeneuve ( KBIN) ; 1♂ Haut Saone [without date], leg. Villeneuve ( KBIN) ; 3♂ 3♀ Centre, Souesmes, Les Vannes , 47.448-2.213, 20-22.viii.2011, 18.viii.2012 (1♀, RMNH.INS.557242; 1♂, RMNH.INS.557244) ; 5♂ Creuse, St. Moreil, La Faurie , 45.852-1.714, 22.viii.2012, 23.viii.2012 (1♂, RMNH.INS.557243), 2.ix.2014, 6.ix.2014 ; the Netherlands 7♂ 2♀ Maastricht, St. Pietersberg , 23.vii.2013, 27.viii.2013, 28.viii.2013 (1♂, RMNH.INS.559427, leg. E. de Bree), 9.ix.2014 .

Diagnosis. T. calceatus is a brown to golden brown dusted Machimus -like species. With a size between 12–18 mm it is on average the largest Tolmerus species present in NW-Europe.

Head: The relatively thin mystax consists of black bristles in the dorsal half and usually reddish bristles in the ventral half. Short hair on scape and pedicel white. Hair on frons just behind antennae white, around ocellar tubercle black. Postocular bristles mostly reddish mixed with some black ones, occipital bristles and hairs yellowish white.

Thorax: Dusted brown to golden brown (pattern of dusting on scutum as is usual for genus). All bristles on scutum black, small hairs on scutum black and short, longer hairs between the post sutural bristles white. Scutellum with 2, usually black, marginal bristles. Wings largely clear, slightly darkened at the apex. Anterior side of femora black with a small red spot just before the apex. All femora black with a small red spot just before the apex on the anterior side and a complete posterodorsal red stripe. The posterior apex of front and middle femora red. Tibiae red with a black apex and a black stripe from the apex on the interior side not reaching the base. Tarsomeres red with a narrow black apex.

Abdomen: Both tergites and sternites with a pattern of dense, brown to golden-brown dusting. Bristles and hairs along the posterior margins of tergites yellowish white. In males, the 8 th sternite has a forked projection with mainly yellowish hairs at the apex.

Terminalia: Extremely similar to T. atricapillus , only the gonostylus is quite different (see plate 1c ).

Ecology. Based on the few observations of the species, it seems that it prefers warm open spaces like herbaceous grasslands and forest clearings. Favourite outlook posts are the leaves of herbs and shrubs like broom ( Cytisus sp.). Mating takes place in head to head position like most Tolmerus species. Deposition of eggs has not yet been observed. A remarkable observation was made on a clearing in a pine forest near Souesmes in central France. On this clearing dozens of specimens seemed to have gathered and sat in the top of broom shrubs chasing each other (a form of hill-topping?). In the surrounding forest no specimens were found, only T. atricapillus and T. pyragra (Zeller) seemed to be present there. Based on the limited available data, it seems that the adults emerge from July to September, with a peak in August.

Figures

PLATE 1. Male Tolmerus calceatus male. A: Lateral view. B. Head in lateral view. C: Gonostylus.