Merostenus (Merostenus) longistylus Gibson, 2017, n. sp.
Creators: name: Gibson, Gary A. P.
Publisher: name: Zenodo
Year: 2017
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Hymenoptera
Eupelmidae
Merostenus
Merostenus longistylus

description: M. (Merostenus) longistylus n. sp.
Figs 56–73
Type material. Holotype ♀ (CNC). “ SOUTH AFRICA: Shephard’s | Valley, Malaise Trap | 31.79324°S 19.10271°E | 20–30.ix. 2005, 523m | Fynbos, J. Schmidt / HOLOTYPE ♀ | M. (Merostenus) | longistylus | Gibson”. Point-mounted by venter of mesosoma; entire except missing left ovipositor sheath; uncontorted.
Allotype ♂ (CNC). Same data as holotype except collected 14–20.X.2005 by J. Schmidt. Paratypes (16♀ & 5♂). South Africa. Same data as holotype (1♀ CNC); same data as holotype except collected 30.IX–14.X.2005 (3♂, including CNC Photo 2016-73, and 6♀, all CNC except 1♂ SAMA) or 14–20.X.2005 (5♀, including CNC Photos 2016-64, 2016-66 and 2016-67, and 1♂, CNC Photo 2016-68, all CNC) or 21–27.X.2005 (1♀ CNC, CNC Photo 2016-65). Farm Glenlyon / Renosterveld, 31.41435°S 19.14488°E, 767m, 3–20.XI.2005, J. Schmidt, malaise (1♂ CNC, CNC Photo 2016-69). W. Cape, West Coast Fossil Park, 3 km 270° W Langebaanweg, 32°58.445'S 18°07.236'E, S. van Noort, D. Larsen, E. Bartnick, Sand Plain Fynbos: 4–11.IX.2002, pitfall trap, LW02-N3-P07 (1♀ SAMA); 18–25.IX.2002, yellow pan trap, LW02-N3-Y249 (2♀ SAMA, including CNC Photo 2016-72).
Etymology. A combination of longus (long) and stylus (stake), in reference to the very long ovipositor of females of this species.
Description. FEMALE (habitus: Figs 56, 58). Length = 1.5–2.8 mm. Head (Fig. 57) dark with at least green and usually variably extensive blue, purple, violaceous and/or coppery lusters; in frontal view about 1.2× as wide as high, and in lateral view about 1.6× as high as long with anterior surface almost uniformly curved; vertex and sometimes ocellar triangle finely coriaceous to transversely alutaceous, but otherwise frontovertex smooth and shiny from about level of posterior ocelli to scrobal depression, scrobal depression and dorsal surface of interantennal prominence also shiny and smooth or in part very finely coriaceous, and lower face distinctly coriaceous to alutaceous; lower face uniformly setose with paler, longer setae than dorsally, with line of short dark setae along inner orbits and transversely along upper margin of scrobal depression, but frons otherwise with only a few scattered dark setae; scrobal depression broadly Π-shaped between inner orbits, the lateral margin acute to carinate near torulus and outcurved from torulus toward lower inner orbit so distinct parascrobal region not differentiated, with broadly arched dorsal margin separated from anterior ocellus by distance similar to POL, and sometimes with tiny, shallow depression evident medially above interantennal prominence; ratio of OOL: POL: LOL: MPOD = 2.2–3.7: 3.2–3.7: 2.0–3.0: 1.0. Antenna (Fig. 59) dark brown; scape strongly compressed, about 2.2–3.0× as long as greatest width with dorsal and ventral margins usually subparallel over most of length but smallest individuals with ventral margin evenly arched, and with both outer and inner surfaces similarly coriaceous-alutaceous and setose except for slender bare band along ventral margin, the outer surface with this region developed as thin flange along about apical three-quarters; pedicel about 1.9–2.1× as long as wide; flagellum clavate with fl1 subquadrate and at least fl2–fl4 longer than wide, but fl6–fl8 shorter, the more apical funiculars slightly transverse [length(width) of pedicel and flagellomeres = 19(9): 8(8): 17(10): 18(12): 17(13): 15(14): 13(14): 12(14): 12(15): 40(15)]. Labiomaxillary complex yellowish and mandibles yellowish to orangish basally and orangish to reddish apically.
Mesosoma (Figs 56, 58) mostly dark brown but with variably extensive and distinct metallic lusters, usually with some green on pronotum and blue to purple or more reddish-violaceous lusters elsewhere under different angles of light. Pronotum divided mediolongitudinally (Fig. 60); collar coriaceous-alutaceous and setose with pale setae except along mediolongitudinal division. Mesoscutum (Fig. 60) with lateral lobes comparatively lowly ^-like angulate with dorsal surface flat behind pronotum but increasingly more deeply concave posteriorly where quite distinctly V-like near transscutal articulation, with lateral lobe dorsolongitudinally carinate for entire or almost entire length; shiny and often virtually smooth, but usually with at least obscure, subeffaced meshlike sculpture, and with row of setae along inner inclined surface of lateral lobe and with two rows of setae along outer lateral lobe. Scutellar-axillar complex (Figs 61, 63) with scutellum elongate-slender, consisting of flat to slightly convex, coriaceous, bare frenum and somewhat more coarsely sculptured, dorsolaterally setose, triangular region anterior to frenum widely separated from transscutal articulation, the anterior part differentiated by abruptly inclined sides but not carinately margined dorsally; axillae elongate-slender, dorsally setose, and anterior to scutellum separated by comparatively large, deep depression such that each axilla narrowed anterolaterally with margin along depression usually carinate. Fore wing (Figs 61, 63) short, disc only about 1.4–1.9× as long as wide, spatulate, with broadly rounded apical margin extending from about anterior margin of propodeum to slightly over base of gaster and then often slightly reflexed apically; disc hyaline or variably distinctly brownish basally, with setose submarginal vein extending at least half length but not completely to apex, and variably conspicuously and extensively setose with white setae, the shortest wings sometimes superficially completely bare but usually with at least a few, sparse, inconspicuous setae apically on ventral surface (Fig. 61) and often more extensively setose over disc and with line of setae within costal cell, and longer wings at least quite distinctly setose (Fig. 63) ventroapically and usually variably densely dorsally, but without marginal setae. Mesopectus (Fig. 62) with white setae ventrally and anterolaterally between prepectus and acropleural sulcus; acropleuron (Fig. 62) broadly curved posteriorly to level of anterior margin of mesocoxa, shiny and mostly smooth but finely coriaceous-alutaceous anteriorly and sometimes obscurely coriaceous along other margins. Metanotum (Fig. 61) with dorsellum delineated as laterally carinate, coriaceous, anteriorly V-like incised, quadrangular region over apex of scutellum. Metapleuron (Fig. 62) bare, smooth and shiny, with anterior margin distinctly sinuate so acutely triangular to sublinear dorsally but abruptly wider over about ventral half, with anterior margin slightly reflexed as inconspicuous, slender flange along posterior margin of acropleuron and smoothly curved as slender flange over base of metacoxa to differentiate a small, bare, ventral region between acropleuron and anteroventral angle of metacoxa. Legs usually at least mostly similarly dark as body, but sometimes tibiae variably extensively paler apically and up to basal three tarsomeres yellowish; mesotibia with row of 5–9 apical pegs (Fig. 64); metacoxa with two separate bands of white setae, one ventrolaterally and one dorsolongitudinally (Fig. 62). Propodeum (Fig. 61) very short medially, with posterior margin Π- to ^-like incurved to anterior margin medially and variably distinctly reflexed as slender flange, most conspicuously in larger individuals, with plical region transversely concave between median and callus, the concave region with 1 seta laterally adjacent to callus; callus lowly convex with spiracle separated from lateral margin by distance similar to own diameter, with line of white setae lateral to spiracle and extensively setose to posterior margin between metapleuron and propodeal foramen.
Metasoma with petiole transverse-quadrangular (Fig. 61). Gaster (Figs 56, 58) dark brown with slight bluish or other metallic lusters similar to mesosoma; tergites meshlike coriaceous at least basally, the apices sometimes variably extensively smooth, and Gt1–Gt5 basally with transverse line of dark setae; Gt5 usually overlying and concealing Gt6 and syntergum, but if syntergum exposed then with transverse dorsal surface bearing paramedial marginal setae anterior to omega-like emargination surrounding similarly melanized supra-anal and subanal plate (Fig. 65); ovipositor sheaths dark, filamentous, and at least as long as gaster and sometimes about as long as body (Fig. 58).
MALE (habitus: Figs 66, 67). Length = 1.0– 1.4 mm. Head (Fig. 68) extensively blue to purple, but under some angles of light with variably extensive violaceous or reddish-violaceous lusters on lower face and sometimes on frontovertex medially, and scrobal depression and sometimes frons laterally more greenish, the scrobal depression sometimes also with some coppery luster; with mostly meshlike sculpture, coriaceous on frons and dorsally within scrobal depression and more coarsely coriaceous to coriaceous-reticulate on lower face, but extensively shiny and smooth or almost so within scrobal depression; with whitish setae on lower face compared to more brownish setae on frontovertex, the setae on frons originating from tiny, pinprick-like punctures; scrobal depression shallow, transversely oval, shinier and bare compared to distinctly differentiated, sculptured, setose parascrobal region along inner orbit, and without evident pit above interantennal prominence; OOL: POL: LOL: MPOD = 1.0–1.75: 3.0–3.7: 1.5–2.0: 1.0; frontovertex 0.58–0.6× head width. Antenna (Fig. 69) dark brown; scape compressedspindlelike with slightly outcurved dorsal and ventral margins, about 2.4–3.2× as long as greatest width; pedicel about 1.6× as long as broad and slightly longer than fl2; combined length of pedicel + flagellum about 1.6× head width; fl1 strongly transverse, anelliform; fl2–clava each with short pedicel basally, with semierect, curved setae of similar length as width of flagellomere, and with obscure, very sparse mps only within about apical half of funiculars; fl2–fl8 oblong, all obviously longer than wide with f2 1.4–1.7× as long as wide and apical funicular about 1.1–1.3× as long as wide; clava about 3.2–3.8× as long as wide excluding pedicel; [length (width) of pedicel and flagellomeres, excluding pedicels = 22(9), 11(7), 2(4), 10(5), 10(7), 12(7), 11(7), 11(7), 10(7), 9(7), 24(7)]. Eye (Fig. 68) comparatively densely and conspicuously setose but with very short setae; [EH: EL: MS = 30: 25: 19]. Labiomaxillary complex yellowish to light brown.
Mesosoma (Figs 70, 71) mostly blue to purple with slight violaceous lusters under some angles of light. Pronotum with collar mostly concealed by head in all specimens, but apparently uniformly covered with pale setae and completely sclerotized. Mesonotum (Fig. 70) entirely, similarly meshlike coriaceous and setose with pale to light brownish setae except for bare frenum. Fore wing (Fig. 72) hyaline with yellowish-brown venation; length about 2.2–2.3× as long as maximum width and length of marginal vein about 0.6× width; cc: mv: stv: pmv = 3.1– 3.6: 2.2–2.3: 1.0: 2.2–2.6; stigmal vein with uncus variably long, separated from pmv by distance less than or greater than own length; costal cell dorsally with line of setae along about apical half to two-thirds of leading margin and ventrally setose along length; disc entirely setose except for variably distinct but slender, oblique bare band behind parastigma and base of marginal vein, the bare band separated by setae from venation and basal and mediocubital folds. Metapleuron (Fig. 71) bare, finely meshlike coriaceous; extending dorsally to near level of anterior margin of propodeum conspicuously anterior of propodeal spiracle, with about ventral two-thirds to threequarters of anterior margin abutting posterior margin of acropleuron, and with posterodorsal margin of acropleuron separated slightly from and lying above level of anterodorsal margin of metanotum. Propodeum (Fig. 73) with median length about 0.4–0.45× distance between transscutal articulation and posterior margin of dorsellum; with median carina and with transverse, crenulate furrow along anterior margin lateral to dorsellum, but otherwise uniformly, finely, meshlike coriaceous or somewhat smoother and shinier medially; callus with comparatively long white setae lateral of spiracle but otherwise bare and lowly convex with spiracle within anterior one-third. Legs (Figs 66, 67) almost entirely dark, but extreme base of protibia pale and extreme bases of meso- and metatibiae more obscurely pale; metacoxa bare except for line of white setae along ventrolateral margin and band of white setae along dorsolateral margin.
Metasoma with petiole dark, smooth and shiny, transversely lunate to trapezoidal with posteriorly divergent sides and posterior margin wider than anterior margin (Fig. 73). Gaster (Figs 66, 67) entirely dark; dorsoventrally flattened to oval in cross-section (Figs 66, 67); Gt1 and Gt2 smooth and shiny and bare except laterally, but subsequent tergites usually obscurely meshlike coriaceous and entirely setose with at least 2 and usually more transverse rows of setae.
Distribution. AFROTROPICAL: South Africa.
Hosts. Unknown.
Remarks. Very long and filamentous ovipositor sheaths differentiate females of M. longistylus from those of all other known Merostenus species with brachypterous females. Fore wing length and setation are also unusually variable compared to the other treated species. Different females have the fore wings extending anywhere from about the anterior margin of the propodeum to slightly over the base of the gaster (cf. Figs 61, 63). Further, the shortest fore wings are the least setose, being bare at least dorsally and sometimes superficially entirely bare, though usually with at least a couple of inconspicuous setae on the ventral surface apically (Fig. 61). The holotype has short fore wings that ventrally are comparatively sparsely though uniformly setose apically beyond the submarginal vein, and there are also setae ventrally in the costal cell. Females with longer fore wings extending to near or slightly over the base of the gaster have these at least more distinctly setose apically on the ventral surface and usually also variably extensively to completely setose dorsally (Fig. 63), though the costal cell is always bare dorsally. Of the 14 Shepard’s Valley females, 7 have short wings and 7 have long wings with overlapping setal patterns among the specimens, whereas all 3 Fossil Park females have long and completely setose wings.
description: Published as part of Gibson, Gary A. P., 2017, Synonymy of Reikosiella Yoshimoto under Merostenus Walker (Hymenoptera: Chalcidoidea: Eupelmidae), with a checklist of world species and a revision of those species with brachypterous females, pp. 1-65 in Zootaxa 4255 (1) on pages 33-37, DOI: 10.5281/zenodo.556479