Mesoconius albiseta, Marshall, 2019

Marshall, Stephen A., 2019, A revision of the genus Mesoconius Enderlein (Diptera, Micropezidae, Taeniapterinae), European Journal of Taxonomy 548, pp. 1-126 : 13-16

Mesoconius albiseta sp. nov.

urn:lsid:zoobank.org:act:65BD76B7-22D2-49B1-B76C-78265FE647D7

Figs 1–2

Etymology

The specific name is a noun referring to the white anterior notopleural bristle, which stands out in contrast to the black posterior notopleural bristle.

Material examined

Holotype

ECUADOR • ♂; Pichincha, Bellavista Cloud Forest Reserve ; 00°1ʹ13ʺ S, 78°40ʹ30ʺ W; 2200 m a.s.l.; 9– 13 May 2009; S.A. Marshall leg.; QCAZ.

Paratypes

ECUADOR • 2 ♀♀; same collecting data as for holotype; one ♀ in alcohol; MYCRO336-18 sequenced for CO 1; DEBU .

Description

LENGTH. 16–17 mm.

COLOUR. Mostly black, but abdominal pleuron with a prominent pattern of black and white vertical bands. Body otherwise with areas of pruinosity or colour as follows: middle of face pale microtrichose, contrasting with shiny black lunule and bright silver microtrichose gena, postgena, and parafacial; inner margin of subantennal area with a narrow shiny strip; clypeus orange-brown, with setulosity restricted to posterior corners, palpus yellow-orange; frontal vitta velvety black. Propleuron with orange central area sharply contrasting with ventral and posterior margins. Mesopleuron with vertical patterns of dense golden pruinosity, katepisternum entirely microtrichose but only posterior third of anepisternum microtrichose; postpronotal lobe and notopleuron also strongly microtrichose, scutum with very short, dense microtrichia forming three longitudinal bands (a central band dark and lateral golden microtrichose bands); golden bands extending on to sides of scutellum. Female with fore tarsomeres 1 and 2 white, except for small black ventral patch at base, tarsomere 3 brown with black setulae, tarsomeres 4 and 5 black; male fore tarsus strongly modified, with tarsomere 1 bicoloured and the strongly swollen, tarsomeres 2–5 black. Fore femur orange on basal half, black distally; mid and hind femora black, except for a narrow orange base, a white ring at middle and brown apex. Tibiae brown. Wing lightly infuscated, slightly darker on apical third. Abdomen brown at base of T1–2, tergites otherwise black; pleuron in both sexes boldly patterned, with tapered black bands extending ventrally from margins of T2–6

HEAD. Epicephalon and paracephalon shiny, indistinctly striate, bare except for patch of setulae around inner vertical bristle; frontal vitta broad anterior to ocelli (0.44× frontal width), tapered to anterior margin of frons, sharply tapered behind ocelli. One strong fronto-orbital bristle inserted near junction of epicephalon and orbital strip. Upper face with a broad, parallel-sided, weakly convex, microtrichose central ridge separated from broad microtrichose parts of subantennal areas by small, shiny, blackbrown area. Postgena with long white setae.

THORAX. Cervical sclerite with a vertical groove separating a subquadrate, convex, partially microtrichose posterior portion from a smaller, pale, mostly bare anterior portion. Scutum with silvery areas as noted above, otherwise finely microtrichose, with scattered small acrostichal setulae near middle and with small dorsocentral setulae forming a distinct row along border between dark central area and microtrichose longitudinal band; postpronotal lobe microtrichose except for shiny anterior face, some small setulae posteroventrally. Notopleuron with a white anterior bristle and a black posterior bristle. Supra-alar bristle white. Dorsocentral bristle strong, white and longer than scutellum in female, black and shorter in male. Apical scutellar bristle very long. Katatergite moderately swollen, entirely setulose, without a point or prominent apex. Vertical row of katepisternal bristles white. Coxae with white anteroventral setae.

ABDOMEN. Abdominal petiole including segment one only, P2 as deep as P3; length of T1+2 double length of T3. Tergites shiny, sparsely microtrichose, with white setulae.

FEMALE ABDOMEN. Oviscape black. Bursa and ventral receptacle small, bursa distally extending as a broad common spermathecal duct. Single spermathecal duct arising laterally at mid point of common spermathecal duct, broad near base then uniformly smooth and parallel-sided before expanding into a convoluted stem leading to a small oval spermatheca. Paired spermathecal duct arising at apex of common duct, broad and rugose from apex of common duct until transforming into a narrower, smooth distal half that ultimately splits into two long, broad, convoluted stems, each ending in a flat-topped smooth spermatheca.

MALE ABDOMEN. Sternites 5 and 6 elongate, tapered anteriorly and notched posteromedially. S7 narrow ventrally, fused with S8 laterally. S8 black, entirely microtrichose, posterior third sparsely setulose. Epandrium elongate, longer than S8, with prominent, tapered, setose posteroventral angles; cercus large, simple and distinct. Basiphallus projecting far posterior to base of distiphallus, basiphallus thus forming a large, lobate epiphallus; distiphallus unusually small, basal part narrowly tubular, apically expanded as a small phallic bulb; distal part of distiphallus narrow and whip-like. Ejaculatory apodeme small, narrow, barely twice as large as sperm pump and much smaller than epandrium.

Remarks

Mesoconius albiseta sp. nov. is externally distinctive for its mostly bright silvery subantennal areas and pale upper face, its several white thoracic bristles, the strongly swollen male tarsus and the colour pattern, with vertical thoracic and abdominal bands. Internally, the very large posterior basiphallus extension (epiphallus) of the male is unique in the genus but the elongate, conspicuously convoluted paired spermathecal stems of the female suggest a relationship to other species of the M. eques group.

Figures

Fig. 1. Mesoconius albiseta sp. nov., external characters. A. Holotype prior to capture, ♂, QCAZ. B. ♂, showing swollen fore tarsomeres. C–D. Paratype prior to capture, ♀, DEBU. E. Pleuron and base of abdomen to show katatergite. F. Head, ♂.

Fig. 2. Mesoconius albiseta sp. nov., internal characters. A. Spermatheca and associated structures. B. Male terminalia, left lateral. Abbreviations: b = basiphallus; bc = bursa copulatrix; c = cercus; cd = common duct; ddp = distal distiphallus; ea = ejaculatory apodeme; hyp = hypandrium; p = phallapodeme; pb = phallic bulb; pd(b) = paired spermathecal duct (basal section); pd(d) = paired spermathecal duct (distal section); pss = paired spermathecal stem; sd = single spermathecal duct; ss = single spermatheca.