Toxomerus flaviplurus (Hall)

Mengual, Ximo, 2011, Black-tie dress code: two new species of the genus Toxomerus (Diptera, Syrphidae), ZooKeys 140, pp. 1-26 : 10

Toxomerus flaviplurus (Hall) Figures 10, 14

Mesogramma flaviplurus Hall 1927: 239. Type Locality: Guatemala, Puerto Barrios [HT ♀, OSU].

Differential diagnosis.

Male with yellow face with a medial broad dark vitta surrounding antennal bases forming narrow dark area between antennal bases and dorsad to antennal bases, black ventrolaterally, yellow pilose, white pollinose laterally. Female face and frons yellow with medial black vitta joining medial black frons vitta until the vertex, surrounding laterally the antennal bases. Scutum black, greenish-brown pollinose with dorsomedial broad bluish pollinose vitta and two submedial bronze pollinose vittae, entirely yellow pilose; postpronotum yellowish-brown, slightly lighter than scutum, notopleuron black; supra-alar area and postalar callus yellowish; scutellum black with broad yellow vitta on lateral and apical margins, pale pilose. Pleuron mostly black, except posterior anepisternum black on posterior third, pale pilose; katepisternum with dorsal yellow macula reduced. Wing membrane light brown, entirely microtrichose. Male abdomen shiny black, pale pilose, with tergum 8 as long or longer than tergum 5; male genitalia with long postanal process ( Borges and Couri 2009: 21, Fig. 47). Female abdomen a bit more oval, shiny black with a black pollinose pattern (Fig. 10)

Length

(5): body, 7.2-7.7 (7.4) mm; wing, 6.6-6.9 (6.8) mm.

Distribution.

Guatemala, Costa Rica, Brazil, Panama, Trinidad*.

Material examined.

2♂ paratypes, 50♂ 37♀.

Remarks.

Toxomerus flaviplurus can have yellow markings in the abdomen, with yellow fasciate vittae on terga 2 to 4 and submedial yellow vittae on terga 3 to 5 (see Borges and Couri 2009: 17, Fig. 28). The species key works for the dark form of this species. Some dark specimens of Toxomerus flaviplurus can have an almost continuous lateral yellow vitta on the scutum. For this reason, Toxomerus flaviplurus appears in two different couplets in the key.

Reemer (2010) synonymised flaviplurus under Toxomerus costalis (Wiedemann) based on the overall similarity of these species after studying photographs of the paratypes of Toxomerus flaviplurus and the holotype of Toxomerus costalis . Reemer (2010: 185, Figs 94, 95) included photographs of new costalis material from Surinam and male and female look similar to pale forms of flaviplurus. The holotype of Toxomerus costalis has glued an abdomen of a Eupeodes species; the head is also glued but it is the original. After the study of the paratypes o f flaviplurus and the holotype of costalis, I found only a minor difference that is within the variability range of this species: the holotype of costalis has the scutellum with a broad yellow vitta on lateral and apical margins. Based on my limited material of Toxomerus costalis and the fact that the holotype lacks the abdomen, I have no morphological characters to disagree with Reemer, but I have molecular evidences to not accept this synonym at this moment. Mengual et al. (2011, but see Mengual 2008) inferred the phylogenetic relationships among the genera Toxomerus and Ocyptamus Macquart, 1834 and their results placed a specimen of Toxomerus costalis from Surinam (identified by M. Reemer) distantly related to a specimen of Toxomerus flaviplurus from Venezuela. The study of more material and a broader sample of specimens for DNA studies are required to better understand these taxa.