Mesoconius lobopoda, Marshall, 2019

Marshall, Stephen A., 2019, A revision of the genus Mesoconius Enderlein (Diptera, Micropezidae, Taeniapterinae), European Journal of Taxonomy 548, pp. 1-126 : 107-109

Mesoconius lobopoda sp. nov.

urn:lsid:zoobank.org:act:F039A155-9663-4D78-ACF7-61C5B0D124A1

Fig. 43

Etymology

The specific name refers to the lobopod-like outgrowths of male abdominal segments 4 and 5.

Material examined

Holotype

COLOMBIA • ♂; Cordillera Occidental , Rio Aguacatal; 2000 m a.s.l.; 1908 [?]; Fassl leg.; BMNH.

Paratypes

COLOMBIA • 1 ♀; same collecting data as for holotype; BMNH • 1 ♂; Cordillera Occidental, Rio Aguacatal ; 1800 m a.s.l.; Fassl leg.; BMNH • 1 ♀; S. Antonio; 2000 m a.s.l.; 16 Feb. 1908; Fassl leg.; BMNH .

All types are part of the C.T. Trechmann bequest to the BMNH (1964-549) and are part of a significant collection of high altitude Colombian micropezids, including several other rarely collected species of Mesoconius .

Description

LENGTH. 17–18 mm.

COLOUR. Abdomen orange-brown, except for black posterolateral corners of T3 and T4 and orange S8- epandrium; thorax mostly black to dark brown, apex of scutellum reddish. Head strikingly bicoloured, upper half black, lower half yellow, except for silvery parafacial and postocular strips, palpus yellowish. Fore femur brown, except reddish apex. Fore tibia of male brown, strongly flattened and sulcate over basal ¾, distally inflated; female tibia unmodified. Fore tarsomere 1 of male flat and greatly expanded, brown on outer surface and brilliantly white on inner surface, black setulose ventrally; female fore tarsomere 1 swollen, white, not flattened; tarsomeres 2–5 white, except for black setulose ventral edges. Mid femur brown basally and distally orange-brown; mid tibia and tarsus brown; hind femur mostly brown basally and distally with some reddish ventral areas and a reddish ring near middle. Hind tarsus brown, except for white basal ¾ of tarsomere 1. Wing evenly and heavily yellow-brown infuscated. Abdominal pleuron pigmentation obscured on all types.

HEAD. Epicephalon, paracephalon and upper half of frontal vitta shiny dark brown, sharply contrasting with orange lower frons; lower part of frontal vitta and interfrontal strip vertically microstriate, identical in colour to smooth orange orbital strips. Outer vertical bristle absent, inner vertical bristle strong, postocellar bristle strong. Two strong fronto-orbital bristles. Antennae separated by width of antennal socket, lunule and facial carina bare, upper face strongly and broadly carinate; lower face flat and microtrichose. Clypeus shiny medially, posterolaterally microtrichose. Occipital setae sparse, postgena densely setulose.

THORAX. Cervical sclerite with a vertical groove separating a brown, microtrichose, subquadrate, indented posterior portion from a small, bare, reddish anterior portion. Prosternum microtrichose and sparsely setulose. Notum microtrichose, with sparse, indistinct rows of small acrostichal and dorsocentral setulae; postpronotal lobe sparsely microtrichose, with some scattered small setulae. Scutellum with two small discal setulae and long apical bristles (longer than scutellum). Katatergite rounded, not prominent, sparsely setulose. Notopleuron with two widely spaced bristles (holotype with an extra anterior notopleural on one side). Vertical row of katepisternal bristles yellow. Coxae with anteroventral golden setae.

ABDOMEN. Abdominal segments 1–3 strongly petiolate, length of T1+2 double that of T3.

FEMALE ABDOMEN. Abdominal sclerites, including oviscape, reddish brown. Bursa broad and short, ventral receptacle small but distinct, basal (undivided) part of spermathecal duct long (as long as single duct), broad, pale and wrinkled; single spermatheca small, slightly broader than duct; paired spermathecal duct double the diameter of paired duct and longer and striate throughout. Paired spermathecae elongate cupshaped, distinctly striate, tapered basally, ducts beyond split with a large, elongate, oval swelling and a distal section with a single S-bend putting spermatheca at right angle to duct.

MALE ABDOMEN. Segments 5–6 with two large cylindrical, membranous lobes at anterior margin of pleuron 6 and four smaller ventral membranous lobes; sternites 4–6 apparently unsclerotized. Synsternite 7–8 simple, S8 orange, similar in size to epandrium. Epandrium with broad, long-setose posteroventral margins, cercus large and distinct. Hypandrium elongate, anterior plate narrow, strap-like. Basiphallus very small, frame-like; not extending beyond base of distiphallus. Basal part of distiphallus broadly tubular, more or less parallel-sided basal to very large phallic bulb, which forms a distinctive distal dorsal notch at origin of distal part of distiphallus; distal part of distiphallus tapered and whip-like, apex broken on only dissected male. Ejaculatory apodeme broad, half size of epandrium.

Remarks

This is one of the most distinctive species of Mesoconius , because of the frontal colour and distinctive male structures. The sharply bicoloured frons, with the red-yellow lower frons and black upper frons, is diagnostic. The very broad first tarsomere on the fore leg is highly distinctive, especially on males, and the remarkable lobopod-like outgrowths of the male abdominal segments four and five are unlike anything else known in the Micropezidae .

Figures

Fig. 43. Mesoconius lobopoda sp. nov. A. Spermathecae and associated structures. B–D. Holotype, ♂, BMNH. E. Abdomen, ♂, left side. F. Abdomen, ♂, ventral view. G. Male terminalia, lateral view, with phallic bulb enlarged in inset. H. Male terminalia, dorsal view. I. Male terminalia, ventral view. Abbreviations: bc = bursa copulatrix; cd = common spermathecal duct; ddp = distal distiphallus; e = epandrium; hy = hypandrium; lo = ʻlobopodʼ pleural lobe of segment 5; pb = phallic bulb; pd = paired spermathecal duct; sd = single spermathecal duct.