Megatrigon nivalis ( Hull, 1964 ) Doczkal & Radenković & Lyneborg & Pape, 2016

Doczkal, Dieter, Radenković, Snežana, Lyneborg, Leif & Pape, Thomas, 2016, Taxonomic revision of the Afrotropical genus Megatrigon Johnson, 1898 (Diptera: Syrphidae), European Journal of Taxonomy 238, pp. 1-36 : 5-10

publication ID	https://doi.org/ 10.5852/ejt.2016.238
DOI	https://doi.org/10.5281/zenodo.3854670
persistent identifier	https://treatment.plazi.org/id/03EA327E-FFE5-EC1E-FD89-EEC8FD2EFDB9
treatment provided by	Valdenar
scientific name	Megatrigon nivalis ( Hull, 1964 )
status	comb. nov.

Treatment

Megatrigon nivalis ( Hull, 1964) , comb. nov.

Figs 1M View Fig , 2N View Fig , 3M View Fig , 4D View Fig , 8 View Fig , 10M View Fig , 11 View Fig M–N, 12L, 16

Eumerus nivalis Hull, 1964: 485 View in CoL . Type locality: South Africa, Northern Cape, Belmont.

Diagnosis

See diagnosis of nivalis group.

Type material

SOUTH AFRICA: ♂, holotype, Northern Cape, Belmont , 23 Feb. 1934, J. Ogilvie ( BMNH). [Examined.] The holotype is in bad condition, with both metalegs and right mesoleg missing (all from femur on), head glued to the thorax, left mesoleg soaked in an unknown substance.

Additional material

NAMIBIA: 1 ♂, Rundu, 31 Jan. 1993, leg. M. Schwarz (coll. M. Hauser); 1 ♀, same locality, 22 Jan. 1993, leg. J. Gusenleitner (coll. M. Hauser) .

Description

LENGTH. Body 11 mm (♂), 12 mm (♀); wing 6.7 mm (♂), 7.3 mm (♀).

HEAD ( Figs 2N View Fig , 3M View Fig ). Face completely densely microtrichiose, only the slightly produced anterior mouth edge and a small area posterior to lateral mouth corner bare of microtrichia. Frons with a dense silver pilosity. Distance between eyes small (0.11 × width of head). Vertical triangle microtrichiose except for between and posterior to the posterior ocelli, postocellar spot small, microtrichiose very narrowly continuing along parasagittal sulci, postocular orbit behind postocular ridge with sparse microtrichia. Postocular area wide, about 1.5 × as wide behind dorsal eye corner than at the narrowest point on ventral half. Posterior eye margin slightly bent anteriorly dorsal to vortex. An ill-defined median furrow on vertex from posterior ocelli to posterior border. Ocellar triangle isosceles. Antenna black, base of

arista bright orange. Pedicel slightly elongate, postpedicel small, oval, sensory pit elongated, forming an oblique slit.

THORAX ( Fig. 4D View Fig ). Mesoscutum extensively and densely microtrichiose: median and submedian stripes extending to the level of wing base (the submedian stripes missing in female, Fig. 4D View Fig ), notopleuron, supraalar area, prescutellar area, transverse suture (the latter incomplete in female, Fig. 4D View Fig ). Scutal pilosity short, semi-decumbent, light (whitish), supraalar setae uniserial (with few extraserial setae), yellow. Notal wing process microtrichiose. Capitulum blackish. Setae on anterior part of anepisternum restricted to posterodorsal half. Proepimeron with long setae. Thoracic pleura bare of microtrichia on posterior part of anepisternum, on katepisternum anterior to the setose parts, and all of meron (lower part dulled by a fine surface sculpture). Protarsus shorter than protibia, stout; tarsomere 1 about as long as wide. Profemur and protibia reddish brown will ill-defined blackened parts, densely microtrichiose posteriorly and dorsally (obscuring surface), thinly microtrichiose anteriorly and ventrally, pilosity white. Tarsomeres 2–5 darkened dorsally.

WING. Costagium with yellow setae, posterior setae short (about as long as diameter of costa distal to costagium). Cells c, r 1, bm, cup and anal lobe with large areas bare of microtrichia, as well as narrow bare stripes along parts of the veins and at the posterior margin of the wing including alula, veins yellowish brown at base, darker brown towards apex.

ABDOMEN ( Fig. 8 View Fig ). Conical [similar to Merodon avidus (Rossi, 1790) ], lateral margins of tergite 2 convergent posteriorly, tergite 3 is 2 × as wide as long, tergite 2 with a median fascia, tergites 3+4 each microtrichiose anteriorly and with a median fascia, tergite 4 with microtrichiose posterior margin. Tergite 2 posteromedially (posterior to fascia) with a large triangular black setose area, most part of tergite 3 (except for fascia and lateral margins) black setose, tergite 4 with small black setose area between anterior and median fascia, otherwise tergites with whitish pilosity. Except for the lateral margin setae are very short, those on posterior margin of tergite 2 not distinctly exceeding margin of tergite, tergites pitted (alveoli). Genital pouch wider than half width of tergite 4 anteriorly. Sternite 1 large. Sternites 2–4 with semi-decumbent, comparatively short, white setae.

Distribution

Afrotropical – Namibia, South Africa ( Fig. 16 View Fig ).