Mesoconius nigripleuron, Marshall, 2019

Marshall, Stephen A., 2019, A revision of the genus Mesoconius Enderlein (Diptera, Micropezidae, Taeniapterinae), European Journal of Taxonomy 548, pp. 1-126 : 35-38

Mesoconius nigripleuron sp. nov.

urn:lsid:zoobank.org:act:E0C3E8FB-3EAF-4AE2-969D-6E6A271C81ED

Figs 11–12

Etymology

This species is named for the darkly pigmented abdominal pleuron.

Material examined

Holotype

PERU • ♀; Cusco, Wayqecha Biological Station , 9 km NE of Challabamba; 13°10ʹ20ʺ S, 71°35ʹ00ʺ W; 2600–2700 m a.s.l.; 1–6 Dec. 2011; S.A. Marshall leg.; MUSM.

Paratypes

PERU • 7 ♀♀, 3 ♂♂; same collecting data as for holotype; three specimens sequenced for CO1: MYCRO075-15, MYCRO078-15, MYCRO327-18; DEBU • 3 ♀♀; same collecting data as for holotype; MUSM • 1 ♀; same locality as holotype; 16–18 Jul. 2014; M. Zhang and B. Sharanowski leg.; Malaise trap; DEBU .

Other material

BOLIVIA • 1 ♀; La Paz, Coroico, Cerro Uchumachi ; 2550 m a.s.l.; 16°12ʹ43ʺ S, 67°42ʹ49ʺ W; 16 Apr. 2001; S.A. Marshall leg.; cloud forest; MYCRO324-15 sequenced for CO1; DEBU .

Description

LENGTH. 17–19 mm.

COLOUR. Head black, except for first flagellomere, which is reddish basally and dark brown distally, and reddish palpus and clypeus. Thorax mostly dark brown to black, apex of scutellum, pleural suture and supra-alar area orange; notum with two broad silvery-golden microtrichose lateral vittae and a weak central vitta (at least presuturally); postsutural part of notum with broad lateral vittae only. Legs of females sharply bicoloured, fore leg black except for mostly orange femur, mid femur narrowly orange at base but otherwise black on basal half and orange distally, hind femur black on basal half and orange distally, mid and hind tibae orange, tarsi mostly black but tarsomere 1 of mid and hind leg pale basally and ventrally. Legs of males variably coloured, mid and hind femora orange basally and with a central white band, with black areas on both sides of white band or with one distinct black band distal to white band. Wing uniformly dark yellowish, without clear spots or bands. Abdomen mostly black, bases of T2 and T3 brown, T2 with an orange posterior corner; T1 of male orange, pleuron uniformly and darkly pigmented.

HEAD. Orbital strip and epicephalon microtrichose, paracephalon shiny, finely striate; frontal vitta weakly delineated, broad anterior to ocelli, with a broad and inconspicuous anteromedial margin widely separated from anterior margin of frons, narrow and sulcate posterior to ocelli; inner vertical bristle strong, with four–five setulae near base; outer vertical bristle and postocellar bristle absent. One strong fronto-orbital bristle inserted in a discrete patch of microtrichia near lower margin of epicephalon. Upper face broad and slightly elevated, face otherwise membranous and microtrichose, subantennal areas shiny, parafacials microtrichose. Clypeus shiny, mostly bare, distinctly striate, microtrichosity restricted to dorsal part of posterolateral corner.

THORAX. Cervical sclerite with a small, bare anterior anterior portion, with a carina separating it from a middle portion that is in turn separated from large posterior, setulose portion by another carina. Notum finely and densely microtrichose, acrostichal and dorsocentral setulae long and in distinct rows, scattered setulae anterolaterally. Postpronotal lobe dull, densely microtrichose, with several scattered small pale setae, anterior margin almost vertical, bare and shiny dorsally; posterior margin microtrichose and steeply sloped. Dorsocentral bristle black, slightly shorter than length of scutellum. Scutellum with four small discal setulae and long, closely spaced black apical bristles (longer than scutellum). Katatergite very prominent, with a long, nipple-like microtrichose pointed process. Notopleuron with two widely spaced black bristles. Vertical row of katepisternal bristles golden. All coxae with golden anteroventral setae.

ABDOMEN. Abdominal segment 1 and base of segment 2 petiolate; T1+2 slightly less than twice as long as tergite 3. T1 setose, with preapical long, thin lateral setae.

FEMALE ABDOMEN. Oviscape bare except for scattered setulae. Bursa elongate, ventral receptacle small and inconspicuous. Single spermathecal duct branching laterally off a short, broad common duct; single spermatheca greatly reduced, single duct almost as long as paired duct, but less than ¼ as wide. Paired spermathecal duct divided into distinct parts, including a rugose basal half that abruptly transforms into a slightly narrower, relatively smooth (indistinctly striate) distal half. Paired spermathecae expanded distally to invaginated apex, surface reticulate, stem (beyond division of paired duct) elongate and conspicuously coiled and tuberculate.

MALE ABDOMEN. Sternite 5 small and narrow; S6 large, tapered anteriorly and notched posteromedially; T6 densely golden microtrichose. Synsternite 7–8 sparsely microtrichose, forming a shiny ring contrasting with dull, microtrichose preceding sclerites and pale microtrichose epandrium; S7 with a very broad but unmodified ventral part. Sternite 8 similar in size to epandrium (longer dorsally, shorter ventrally), epandrium elongate, sparsely setose except for a dense patch of setae posteroventrally; cerci prominent, large, elongate and apically bilobed, together forming a medially keeled tripartite distal shield strongly projecting posteroventrally. Hypandrium elongate and slender, extending to anterior margin of T6. Basiphallus small, not extending beyond base of distiphallus. Basal part of distiphallus narrow basally, distally abruptly expanding to enclose a small phallic bulb with a small ventral sac and an elongate dorsal sac; distal part of distiphallus slender, twice as long as basal part. Ejaculatory apodeme very small, smaller than attached sperm pump.

Remarks

The distinctive black, yellow-winged females of this species usually differ from those of other black species by their sharply bicoloured mid and hind femora with dark bases and yellow-orange distal halves, although the one female specimen from Bolivia has leg colour like males from Peru. Males, which can be strikingly different in colour but are identical in CO1 sequence to the females (sequences 078 and 327 are male and female, respectively), key out with M. auristrigatus Enderlein, 1922 , although they are generally darker, with a darker katatergite, dark thoracic bristles, a dark reddish brown palpus and much darker femoral banding (compare Figs 5A and 11D ). One of the males has only one distinct black band distal to the white band on both mid and hind femora ( Fig. 11D ); the other two have black areas on both sides of the white band. Many distinctive features (elongate and curved cercus, characteristic epandrium, elongate and posteriorly expanded sternite 6, darkly pigmented female abdominal pleuron) suggest that M. nigripleuron sp. nov. and M. auristrigatus are closely related, despite the strikingly different females and the distinct male cerci.

Figures

Fig. 11. Mesoconius nigripleuron sp. nov., living specimens, Peru. A–C. ♀♀. D. ♂.

Fig. 12. Mesoconius nigripleuron sp. nov., internal characters, Peru. A. Male terminalia, lateral view. B. S6 to S8, ♂. C. Abdomen, ♂. D. Spermathecae and associated structures (inset: one of the paired spermathecae with a partially uncoiled stem). E. Male epandrium and cerci, posterodorsal view. Abbreviations: c = cercus; ddp = distal distiphallus; e = epandrium; ejac = ejaculatory apodeme; hy = hypandrium; pa = phallapodeme; pb = phallic bulb.

Fig. 5. Mesoconius auristrigatus Enderlein, 1922, external characters. A, C. Living ♀♀, Ecuador. B. Head, ♀. D. Holotype, ♀, MNBG. E. Pleuron and base of abdomen to show orange katatergite.