Megatrigon tabanoides, 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 : 28-29

publication ID	https://doi.org/ 10.5852/ejt.2016.238
DOI	https://doi.org/10.5281/zenodo.3854664
persistent identifier	https://treatment.plazi.org/id/03EA327E-FFFA-EC0B-FDC7-EB0AFD91F8C4
treatment provided by	Valdenar
scientific name	Megatrigon tabanoides
status	sp. nov.

Treatment

Megatrigon tabanoides View in CoL sp. nov.

urn:lsid:zoobank.org:act:AF0AED98-F365-434F-A0FF-EA337D9374D7

Figs 1K View Fig , 2L View Fig , 3K View Fig , 5C View Fig , 7K View Fig , 10K View Fig , 11K View Fig , 12J View Fig , 16 View Fig

Diagnosis

Black, large species, with white microtrichiose stripes on tergites ( Figs 1H View Fig , 7K View Fig ); wing membrane brown along the veins ( Fig. 5C View Fig ); alula bare of microtrichia at posterior margin; all tibiae orange without dark ring; tarsomeres 4–5 black dorsally (rest of tarsomeres can be shaded); only species with intraalar microtrichia on mesoscutum; postsutural pilosity of mesoscutum mainly black.

Etymology

The species epithet, which is formed as an adjective, is derived from the Latin word tabanus (= horse fly), alluding to the resemblance of this species to a horse fly of the genus Tabanus Linnaeus.

Type material

Holotype

SOUTH AFRICA: ♁, Western Cape, 5 km E of Lambert’s Bay , westcoast strandveld, 31 Aug. 1981, J. Londt, L. Schoeman & B. Stuckenberg leg. ( NMSA).

Paratypes

SOUTH AFRICA: 1 ♁, Northern Cape, Bowesdorp, Sep. 1941, museum staff leg. ( SAMC); 1 ♁, Northern Cape, 16 km S of Steinkopf, 1 000 m, 31 Aug. 1989, Stuckenberg, Londt & Crosser leg. ( NMSA); 1 ♁, Western Cape, Pakhuis Pass, 1961, museum staff leg. ( SAMC); 2 ♁♁, Western Cape, 5 km E of Lambert’s Bay, 31 Aug. 1981, Londt, Schoeman & Stuckenberg leg. ( NMSA); 2 ♁♁, Western Cape, Cape Pen., Hout Bay, 11 Sep. 1967, E.S. Ross & A.R. Stephen leg. ( CAS); 3 ♁♁, N Cape, Hantams Nat. Botanical Garden Neuwoudville, Rocky ridge, 750 m, 31°24ʹ49″ S, 19°09ʹ35″ S, 11 Sep. 2012, J. & A. Londt leg. ( NMSA).

Description

LENGTH. Body 12.0 mm, wing 7.5–8.0 mm.

HEAD ( Figs 2L View Fig , 3K View Fig ). Distance between eyes, 0.16–0.17 width of head; the width of post-ocular orbit dorsally a little larger than in M. argenteus comb. nov. 0.10–0.11 × width of head; microtrichia on head reduced: on face traces of microtrichia along eye margin, wide microtrichiose area below antennae continuing as tiny medial facial stripe; frons and vertex shiny; microtrichia on postocular orbit do not exceed postocular ridge.

THORAX. Lateral microtrichiose stripes on mesoscutum missing, submedian stripes indistinct ending as a spot at the level of transverse suture, conspicuous intraalar microtrichiose stripe.

WING ( Fig. 5C View Fig ). Capitulum brown.

LEGS. Pro- and mesofemur partly black, but orange at base, apex, and anteriorly in distal half; metafemur mainly black with blue or violet luster, but orange-brown at base and in some specimens also ventrally; hairs on legs mainly white with more or less numerous short black setae on all femora and tibiae, black long posteroapical tuft on metatibia, tarsi dorsally predominately covered by black setae.

ABDOMEN ( Figs 1K View Fig , 7K View Fig ). tergites 2–4 black, with oblique white microtrichiose fasciae almost connected in the middle; triangular on tergite 2 and touching posterior corner, on tergites 3+4 separated from lateral margins (or barely touching on tergite 3 in some specimens). Male genitalia in Figs 10K View Fig , 11K View Fig , 12J View Fig .

Distribution

Afrotropical – South Africa (Northern and Western Cape) ( Fig. 16 View Fig ).

sexfasciatus group

Diagnosis

Katepisternum with a posterodorsal and a small posteroventral pile patch, with or without a few short setae below the dorsal patch. The bare, flat posterior margin of tergite 1 (almost) entirely without microtrichia. Base of wing entirely microtrichiose or at most with small bare areas in cells br, bm, or cup. Anepisternal setae saw-like. Tarsomere 1 of protarsus anterodorsally without black spinules between the yellow setae. ♁: Sternite 4 with inflated caudal lobes, partly without microtrichia, and with a small accessory lobe close to the base of the lobes. Genital pouch large, more than half as wide as abdominal segment 4 at anterior margin. Posterior surstyle lobe ( Fig. 13E View Fig :y, F:y) straight, without hook, directed medially. Median surstyle lobe ( Fig. 13E, F View Fig :w) setose along posterior half of ventral margin, on median surface without accessory lobe, without microtrichia, its posterior end extended, forming a wide rounded lobe directed posteromedially. Cerci ( Fig. 10L View Fig :z) with pointed apex, with sclerotized and setose ventral surface. Subepandrial sclerite strongly curved, its anterior part almost parallel to the posterior part, a complete sclerotized bridge at its anterior end, the posterior part microtrichiose on full length, without a bulging ‘pad’ ( Fig. 13G View Fig :z). Hypandrium ( Figs 11L View Fig , 12K View Fig ) with a very wide base and lateral ‘shoulders’ between the wide proximal and the narrower distal part, apex slightly produced beyond ctenidium and blunt. Ejaculatory apodeme large. ♀: tergite 5 and sternite 5 with posteriorly directed setae, ovipositor with moderately thick setae, without tooth.

Included species

Megatrigon flavimarginatus ( Hull, 1964) comb. nov. ( Eumerus ; holotype in BMNH, examined). Megatrigon jacobi (Hervé-Bazin, 1913) comb. nov. ( Eumerus ; holotype in MRAC, examined).

= Eumerus connexus Hull, 1964 , syn. nov. (holotype in BMNH, examined).

Megatrigon sexfasciatus Johnson, 1898 (holotype in BMNH, examined).

Due to the lack of sufficient material, the species of the sexfasciatus group are not (re)described in the present account. Megatrigon jacobi comb. nov. ( Figs 1L View Fig , 2M View Fig , 3L View Fig , 7L View Fig , 13E View Fig ) is a distinctive species readily recognised by the reduced mouthparts and related features of the lower parts of the head (similar to Merodon bombiformis Hull, 1944 ). The identity of M. sexfasciatus remains obscure. The material that has been available for the present study consists of males of several species that in external characters are very similar to the female holotype of M. sexfasciatus . At present we cannot assign any of the available males to the nominal taxon M. sexfasciatus . There are several ‘morphs’ similar to the type of M. flavimarginatus comb. nov. in the available material. However, as most of these are represented by singletons, we are unable to assess the significance of the observed, often slight, morphological differences and for that reason we refrain from describing them here. More material in good condition is needed to uncover the species diversity in the sexfasciatus group, but we expect that a good number of distinct species will be discovered.