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

description: Key to species of Merostenus with brachypterous females
1 Female..............................................................................................2
- Male............................................................................................... 11
2(1) Mesosoma in lateral view with apex of scutellum protuberant over underlying dorsellum (Fig. 132) and in dorsal view propodeum with transverse carina dividing anterior concave portion under apex of scutellum from posterior portion behind scutellar apex (Fig. 131); mesotibia with patch of strong spines apically over base of mesotarsus but not row of pegs; head green and meso- and metasoma yellowish to orange with some brown markings (Figs 125, 126); outer surface of metacoxa entirely and about ventral half of metapleuron setose (Fig. 132)..................... Merostenus (Reikosiella) melinus (Yoshimoto)
- Mesosoma in lateral view with dorsellum subvertical, cuplike over apex of scutellum and in dorsal view propodeum variable in structure but without transverse carina dividing plical region into anterior and posterior portions; mesotibia with variable number of pegs in row apically over base of mesotarsus; other features variable, but not in combination......3 [M. (Merostenus)]
3(2) Pronotum divided medially (Figs 26, 60)...................................................................4
- Pronotum uniformly sclerotized (Figs 33, 41, 86, 93, 100) even if sometimes with paler line mediolongitudinally (Fig. 41) or short mediolongitudinal furrow posteriorly (Fig. 100: arrow)..............................5 [excavatus species-group]
4(3) Flagellum with at least fl3 and fl4 white, and fl5 somewhat lighter yellowish-brown in contrast to other darker brown flagellomeres (Figs 22, 24); ovipositor sheaths short and rigid, exserted beyond syntergum by only about one-fifth length of gaster (Fig. 29); scutellar-axillar complex longitudinally strigose without large depression between axillae anterior to scutellum (Figs 26, 28); fore wing slender and tapered to angulate apex (Fig. 28); propodeum with posterior margin widely separated from anterior margin and with median carina (Fig. 28)............................ M. (Merostenus) congoensis n. sp.
- Flagellum entirely dark (Fig. 59); ovipositor sheaths long and filamentous, exserted beyond syntergum for distance at least equal to length of gaster (Fig. 58); scutellar-axillar complex meshlike coriaceous to coriaceous-imbricate and with large depression between axillae anterior to scutellum (Figs 61, 63); fore wing spatulate with broadly rounded apical margin (Figs 61, 63); propodeum with posterior margin incurved to anterior margin medially (Fig. 61)....................................................................................................... M. (Merostenus) longistylus n. sp.
5(3) Antenna with scape to fl2 yellowish (Fig. 77); fore wing right-angle bent with about basal half of disc membranous and apical half consisting only of dark, linear venation (Fig. 77: insert); propodeum strongly transverse with narrow plical region deeply concave on either side of high median carina and mesal to convex callar regions (Fig. 79); scutellar-axillar complex with each axilla almost flat except for indistinct mediolongitudinal carina (Figs 78, 79); syntergum recurved apically as posteriorly rounded syntergal flange (Figs 75, 81) [New World]............................... M. (Merostenus) mexicanus n. sp.
- Antenna sometimes with scape and pedicel yellowish but flagellum dark; fore wing flat over body and disc membranous to apex; propodeum variable, but if similar to above then axillae longitudinally striate-strigose; syntergum flat with posterior margin transverse [Old World]........................................................................... 6
6(5) Scutellar-axillar complex with each axilla at least as large as scutellum and longitudinally striate-strigose (Fig. 43); propodeum (Fig. 43) with posterior margin sinuately incurved almost to anterior margin such that medial margins contiguous over much of length and curved up to form high median carina and forming narrow plical region between cone-like protuberant callar regions (Figs 43, 44); fore wing with disc short-spatulate, only slightly longer than wide and extending only to about level of anterior margin of scutellar frenum (Fig. 43); antenna with scape yellow (Figs 39, 42) [Palaearctic]............................................................................................ M. (Merostenus) excavatus (Dalman)
- Scutellar-axillar complex with each axilla much smaller than scutellum and smooth to finely coriaceous; propodeum with posterior margin distant from anterior margin, only shallowly, Π-like incurved, and broad plical region with median carina in almost same plane as callar regions; fore wing usually with disc elongate-spatulate, much longer than wide and extending to base of gaster; antenna sometimes with scape dark [Afrotropical]................................................ 7
7(6) Antenna with scape foliaceously compressed and flagellum robust-clavate with all funiculars strongly transverse (Figs 90–92); metapleuron bare (not to be confused with ventral setose region between acropleuron and meso- and metacoxae, Fig. 95); scutellar-axillar complex with scutellum carinate anteriorly between longitudinally carinate axillae (Fig. 94)...................................................................................... M. (Merostenus) platyscapus n. sp.
- Antenna with scape slender and flagellum gracile-clavate with all or most funiculars quadrate to longer than wide (Figs 34, 85, 101, 117); metapleuron mostly setose (Figs 35, 88, 102, 120); scutellar-axillar complex with scutellum uniformly convex and oval, and axillae not distinctly carinate (Figs 36, 87, 103, 119)..................................................8
8(7) Fore wing extending only to about level of posterior margin of propodeal spiracle (Fig. 87); head with frons (Fig. 83) and mesoscutum (Fig. 86) smooth and shiny; scrobal depression shallow and high O-like, about as high as wide (Fig. 83).............................................................................. M. (Merostenus) micropterus n. sp.
- Fore wing extending to base of gaster (Figs 36, 103); head either with frons and mesoscutum coriaceous to reticulate (Figs 31, 98) or scrobal depression distinctly concave and transversely Π-like (Fig. 115)..................................... 9
9(8) Mesoscutum with subcircular pit on lateral lobe near mid-length (Fig. 33: arrows); head with frons finely coriaceous between scrobal depression and anterior ocellus (Fig. 31); mesoscutum coriaceous (Fig. 33); body mostly dark brown, including entire gaster (Figs 32, 34)........................................................... M. (Merostenus) distigma n. sp.
- Mesoscutum uniformly sclerotized without pits; head and mesoscutum either smooth and shiny or more strongly reticulate than above; body extensively orangish to orangish-brown, including basal two gastral tergites........................10
10(9) Head with face (Fig. 98), mesoscutum (Fig. 100) and most of gaster (Fig. 104) strongly reticulate; scrobal depression shallow and high Π-like, about as high as wide (Fig. 98).................................. M. (Merostenus) reticulatus n. sp.
- Head between scrobal depression and anterior ocellus (Fig. 115), mesoscutum (Fig. 118) and gaster (Fig. 121) smooth and shiny; scrobal depression distinctly concave and transversely O-like (Fig. 115)........... M. (Merostenus) speculum n. sp.
11(1) Metapleuron setose within ventral half (Fig. 111)................................. M. (Merostenus) reticulatus n. sp.
- Metapleuron bare or with at most one or two setae anteroventrally (Fig. 50: insert).................................12
12(11) Metapleuron extending dorsally to level equal with anterior margin of spiracle (Fig. 55); propodeum with callus usually at least noticeably convex and often variably distinctly cone-like produced (Fig. 55), but at least spiracle positioned near mid-length (Fig. 54); length of pedicel + flagellum more than twice head width and funiculars beyond fl1 more than twice as long as wide (Fig. 52); fore wing elongate-slender, with marginal vein similar in length to width of wing and with disc uniformly setose (Fig. 53)............................................................... M. (Merostenus) excavatus (Dalman)
- Metapleuron extending dorsally obviously anterior to level of spiracle (Fig. 71); propodeum with callus not distinctly convex and spiracle positioned within about one ocellar diameter from anterior margin (Figs 70, 73); length of pedicel + flagellum less than twice head width and funiculars beyond fl1 less than twice as long as wide (Fig. 69); fore wing comparatively broad and short with marginal vein only about 0.6× width of wing and disc basally with variably conspicuous, oblique bare band separated by setae from venation and basal and mediocubital folds (Fig. 72)................ M. (Merostenus) longistylus n. sp.
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 21-22, DOI: 10.5281/zenodo.556479