Merostenus (Merostenus) platyscapus 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 platyscapus

description: M. (Merostenus) platyscapus n. sp.
Figs 90–97
Type material. Holotype ♀ (BMNH). [South Africa] “ Mossel Bay, | Cape Province. | January, 1922. / S. Africa. | R.E. Turner. | Brit. Mus. | 1922—67. / NHMUK 010353723 / HOLOTYPE ♀ | M. (Merostenus) | platyscapus | Gibson ”. Glued by right side to card rectangle; entire but left hind leg including coxa detached from body and glued separately to point; contorted.
Paratypes (3♀). South Africa. E. Cape Prov., Katberg, R.E. Turner: 4000 ft, XII.1932, Brit. Mus. 1933-69 (1♀ BMNH, NHMUK010353724); 15–30.I.1933, Brit. Mus. 1933-108 (1♀ BMNH, NHMUK010353725). Pondoland, Port St. John, 15–31.VIII.1923, R.E. Turner, Brit. Mus. 1923-463 (1♀ BMNH, 2016-70, NHMUK 010353726).
Etymology. A combination of platys (broad) and scapus (stem), in reference to the very strongly compressed scape of females of this species.
Description. FEMALE (habitus: Fig. 90). Length = 2.1–2.5 mm. Head (Fig. 91) dark brown or at most with very slight purple to bluish luster on frontovertex under some angles of light; in frontal view subquadrate, about 1.2× as wide as high, and in lateral view lenticular, about 1.6× as high as long, but with lower face abruptly angled relative to much longer, uniformly curved frontovertex; frontovertex and parascrobal region along about dorsal half of scrobal depression smooth and shiny except sometimes for scattered setiferous pits, and frons at least with small depression below anterior ocellus and sometimes with more distinct sulcus extending partly between ocellus and scrobal depression, but about ventral half of parascrobal region and scrobal depression strongly, transversely reticulate-rugose, scrobes and dorsal surface of interantennal prominence above level of toruli finely coriaceous, and remainder of interantennal prominence and lower face more or less granular; sculptured part of parascrobal region, more strongly sculptured part of interantennal prominence, and lower face uniformly setose with dark setae, but frontovertex and smooth part of parascrobal region with only sparse, scattered dark setae sometimes originating from shallow depressions or pits, and scrobal depression and more finely sculptured part of interantennal prominence bare; scrobal depression deep, abruptly inclined above interantennal prominence, with lateral margin directed dorsally near lateral limit of torulus to differentiate distinct parascrobal region along lower inner orbit, but dorsally more ^-like incurved toward median and separated from anterior ocellus by distance similar to LOL; ratio of OOL: POL: LOL: MPOD = 1.5: 3.25: 1.9: 1.0. Antenna (Fig. 92) dark brown; scape foliaceously compressed, about 1.6× as long as greatest width, broadest apically and narrowed basally, with ventroapical margin extending to apex of fl1 when flagellum held at right angle to scape, the inner surface uniformly coriaceous-alutaceous, setose, and in one plane, but outer surface with expanded region thinner, bare, and more finely sculptured than dorsally thicker, setose part; pedicel about twice as long as wide and about as long as combined length of basal three funiculars; flagellum robust with fl1–fl8 subequally long and strongly transverse, with clava about 1.75× as long as wide and almost as long as combined length of apical four funiculars. Labiomaxillary complex dark brown but mandibles lighter, reddish.
Mesosoma (Fig. 90) yellowish-brown to dark brown with variably extensive and distinct violaceous to purple lusters. Pronotum (Fig. 93) completely sclerotized; collar bare, smooth and shiny dorsomedially but neck, lateral panels, and collar posteriorly meshlike coriaceous and sparsely setose. Mesoscutum (Fig. 93) with lateral lobes strongly ^-like angulate from midline, more deeply anteriorly than posteriorly, but carinately margined dorsolongitudinally to abruptly upcurved transverse region along anterior margin, the upcurved region carinate laterally behind spiracle and medially evident as triangular surface between angulate lateral lobes; shiny and smooth with line of 3–5 setae in row along inner inclined surface and similar row of setae along outer inclined surface. Scutellar-axillar complex (Fig. 94) with scutellum lowly convex posteriorly and tapered anteriorly with abruptly inclined sides forming mediolongitudinal carina over about anterior two-thirds that extend to near transscutal articulation, with dark setae only on convex portion anterior to frenum; axillae elongate-slender, wedgelike with abruptly inclined sides forming mediolongitudinal carina along length and with line of setae along outer surface dorsally. Fore wing (Fig. 94) extending flat on mesosoma over base of propodeum to about level of posterior margin of spiracle; disc brownish, about 2.3× greatest width, the surface distinctly roughened to undulating but bare except for setose submarginal vein extending most of length, and tapered apically to acute angle. Mesopectus with white setae ventrally and linearly along acropleural sulcus; acropleuron (Fig. 95) broadly curved posteriorly to level of anterior margin of mesocoxa, meshlike reticulate to obliquely strigose anteriorly and more meshlike coriaceous elsewhere except smooth and shiny medially. Metanotum (Fig. 94) with dorsellum vertically raised over apex of scutellum with paramedial longitudinal carinae. Metapleuron (Fig. 95) bare, meshlike coriaceous to coriaceous-reticulate, with anterior margin reflexed as slender, smooth flange over about ventral half behind posterodorsal margin of acropleuron, and smoothly curved into similar flange above metacoxa so as to differentiate a transverse-rectangular, setose, ventral region between acropleuron and anteroventral angle of metapleuron. Legs (Fig. 90) with front leg mostly brown except apex of tibia and tarsus lighter, more yellowish, middle leg similar to front leg except tibia more extensively to entirely yellowish-brown to yellow, and hind leg with femora brown but coxa yellowish at least apically, and tarsus and tibia mostly to entirely yellow; mesotibia without distinct apical pegs in any specimen (Fig. 97); metacoxa with two separate bands of white setae, one ventrolaterally and one dorsolongitudinally. Propodeum (Fig. 94) long, medial length about 0.5× distance between transscutal articulation and posterior margin of dorsellum; posterior margin shallowly, broadly incurved, and anterior margin slightly raised medially as transverse flange behind dorsellum, with plical and callar regions indistinctly differentiated and similarly meshlike coriaceous-reticulate; callus with spiracle abutting lateral margin and opening faced laterally, with white setae between spiracle and posterolateral margin of propodeal foramen.
Metasoma with petiole transverse-quadrangular. Gaster (Figs 90, 96) dark brown or with variably distinct violaceous, blue to purple lusters dorsally; tergites meshlike coriaceous to coriaceous-imbricate with transverse line of long dark setae except about basal half of basal tergite more finely sculptured and syntergum uniformly setose; syntergum in dorsal view (Fig. 96) with posterior margin transverse; supra-anal plate not visible; ovipositor sheaths yellowish, projecting only slightly beyond syntergum.
MALE. Unknown.
Distribution. AFROTROPICAL: South Africa.
Hosts. Unknown.
Remarks. Although the species description is based on four females, one is mounted on a card triangle upside down and two of the other three are contorted so that several features are described based on just one female. However, antennal structure readily distinguished females from those of all other brachypterous Merostenus, the scape being foliaceously compressed and the flagellum having strongly transverse funiculars (Fig. 92). Females of M. longistylus also have the scape obviously compressed, but the flagellum has more elongate funiculars similar to the other treated species (Fig. 59). Females of M. platyscapus also differ from the other four Afrotropical excavatus -group species in apparently having a bare metapleuron. However, as discussed under monophyly and relationships of the excavatus species-group, there is a setose region below the metapleuron between the acropleuron and metacoxa (Fig. 95) that might represent a secondarily differentiated part of the metapleuron. Scutellar-axillar structure is unique among the species treated, with each elongate-slender axilla as a dorsolongitudinally carinate angulate lobe and with the scutellum narrowed into a similarly slender carinate lobe over almost the anterior two-thirds (Fig. 94). The single uncontorted female appears to have both the anterior margin of the mesoscutum (Fig. 93) and the propodeum behind the dorsellum raised such that V-like margins are formed, into which the posterior margin of the pronotum and dorsellum, respectively, fit into when the mesonotum is arched. However, better preserved and mounted specimens are required to confirm this structure. Although males are unknown, it is quite possible they have the metapleuron partly setose anteroventrally, as discussed under monophyly and relationships of the excavatus species-group.
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 42-45, DOI: 10.5281/zenodo.556479