Toxomerus nitidus (Schiner)

Mengual, Ximo, 2011, Black-tie dress code: two new species of the genus Toxomerus (Diptera, Syrphidae), ZooKeys 140, pp. 1-26 : 14-15

Toxomerus nitidus (Schiner) Figure 24

Mesogramma nitida Schiner 1868: 349. Type locality: South America [Venezuela] [ST ♂, NMW].

Mesogramma ovata Hull 1942b: 19. Type locality: Panama, Yape, Tuirar [HT ♀, MCZ] syn. n.

Differential diagnosis.

Species with yellow face and a medial black facial vitta in both sexes, geba black. Scutum black, green-bronze pollinose with a medial bluish-white pollinose vitta, sometimes with two submedial whitish vittae. Postpronotum yellow and notopleuron partly yellow, usually with triangular yellow macula anteriorly narrowing towards transverse suture. Wing partly bare basally, with costal cell entirely microtrichose and brown, darker than the rest of the wing except stigma. Male abdomen usually bicolor, with terga 1 and 2 black (tergum 1 with yellow anterior corners) and terga 3 to 5 reddish-orange; postanal process of the male gentialia long. Female abdomen usually shiny black with black lateral margins; tergum 2 with submedial black pollinose fascia and terga 3 and 4 with four black pollinose vittate maculae (Fig. 9).

Species close to Toxomerus dispar and Toxomerus sp. 3 but males of nitidus have black facial vitta and notopleuron partly yellow.

Length

(5): body, 6.1-7.4 (6.9) mm; wing, 5.5-6.9 (6.1) mm.

Distribution.

Guatemala, Costa Rica, Panama, Colombia.

Material examined.

2♂ syntypes, ♀ holotype of ovatus, Non-type material: 7♂ 10♀.

Remarks.

Males of Toxomerus nitidus always have a bicolored abdomen and females may have yellowish markings as noted by Hull (1943) (see Fig. 9), although most of the studied specimens had shiny black abdomens with a black pollinose pattern.

Toxomerus nitidus has been cited few times after its original description but only in catalogues (see Appendix I). I had the possibility to study two syntypes of Toxomerus nitidus and compared them with males of Toxomerus ovatus at USNM. Male genitalia were identical and females of ovatus did key out as nitidus. Thus, I realized that Toxomerus nitidus was only known from male specimens. Therefore, Toxomerus ovatus is here considered to be a junior synonym of Toxomerus nitidus .