Striatovertex Schick, Forshage & Nordlander, 2011, new genus

Striatovertex new genus

Type species: Psilodora nudipennis Kieffer, 1907

Diagnosis. Large black-reddish eucoilines with more or less hairless wings (fig. 1), lacking hair fringe and with membrane pubescence mostly reduced to punctiform hair bases (fig. 7). They are distinguished from Eucoilini with strongly reduced wing pubescence (Eucoila, Bothrochacis, some Trybliographa) by each of the following characters: posteroventral corner of metapleuron flat, rounded and pubescent ("pvc" in fig. 2, compare with the raised, oblique hairless corner in Eucoilini in fig. 3), very narrow and shallow subalar pit ("sap" in fig. 2, compare with the deep round pit in Eucoilini in fig. 3), F1 (and not F2) of male antennae modified. From its close relatives Odontosema and Epicoela of Ganaspini, and rather similar Lopheucoila and Dettmeria of Zaeucoilini, they can be distinguished by the following combination: a high, emarginate, not remarkably broad pronotal plate (fig. 4), lack of keel on mesoscutum, posterior margin of scutellum rounded without projections (fig. 5), glandular pit of scutellar plate situated near hind margin (fig. 5). Other diagnostic features (none unique) include the striate (usually heavily striate) vertex (fig. 6), and the characteristic row of stout setae on subcosta (conspicuous as wing is usually otherwise hairless) (fig. 7).

Description. Length 2.8– 5 mm. Head and mesosoma black, red or reddish-brown, smooth and shiny, with more or less sparse setae; mesosoma shining black or red.

Head with slightly protruding compound eyes. Temples nearly as long as eyes. Occipital carina absent, this area and posterior area of vertex and temples diagonally striate. Frons, vertex, occiput bare and shiny. Ocellar plate raised above surface of frons by nearly diameter of large ocellus. Antennal sockets distinctly protruding in lateral view. Eye diameter approximately half length of face (from ocelli to mandibular bases). Face and genae with very few short scattered setae; postgenae with dense, woolly pubescence. Mandibles not densely hairy, with only about ten long setae visible on outside surface, with 2–3 teeth. Palpal formula 4-2. Apical segment of maxillary palpi weakly securiform.

Antennae in female 13-segmented, no longer than head plus mesosoma. First flagellar articles (F1-F3) narrow and decreasing in length distally; F4-F11 moniliform with apical article longer and slightly wider than preceding ones; F4 and F5 (plus F6 and F 7 in some species) with few scattered rhinaria (multiporous plate sensillae), F6-F11 (or F8-F11) with rhinaria throughout visible surface. Entire antennae with whorls of stout setae, each seta nearly length of club article diameter. Male antennae 15-segmented, length about 25% longer than body length. Antennae slender; F1 slightly curved, F2 longer than F1, both shorter than remaining subequal articles. Each rhinarium extending 25–30% length of segment.

Mesosoma smooth and glossy, high; length only about 15% longer than height. Pronotal plate with lateral cavities open, dorsal margin raised above level of mesoscutum and broadly emarginate, nearly bilobed. Ridges extending from sides of posterior part of pronotal plate very short and not visible across anterior dorsal corner of lateral part of pronotum. Pronotum with area of woolly pubescence inside upper half of its ventral border and beneath pronotal plate, few longer setae scattered across lateral parts. Mesoscutum weakly arched, highest area of curve rising not more than 1/8 length of mesoscutum. Depressions inside posterior lateral margins dorsally broad grooves just above area of tegulae. Mesoscutum generally smooth and shiny with few scattered hairs. Scutal sulcus weakly arched between protruding corners of axillae. Lateral bars of scutellum long, striate laterally and smooth dorsally. Scutellum distinctly margined laterally with perpendicular ridges; posterior part extending back beyond metanotum; ridged margin angled obliquely backwards; row of long stout setae just inside posterior margin of scutellum, Dorsal surface of scutellum with a row a stout setae inside lateral margin, sculpture reticulate with depressions largest near margin, decreasing in size towards center, turning into punctures on the lateral parts of the scutellar plate. Scutellar plate varying in shape from narrow teardrop-shaped oval to nearly round, arched in lateral view, surface smooth and concave; glandular pit in posterior part of varying shape, lateral rows of setae very short, visible only in median part, with 2–3 pairs of setae. Scutellar foveae generally round, smooth and glossy. Mesopleuron high, glossy with few scattered hairs; subalar pit reduced to very shallow depression. Mesopleural carina complete but thin; precoxal carina complete. Metanotum with distinct plate, emarginate ventrally, visible posterodorsally. Metapleuron high and rectangular, overall convex; hind margin strongly raised, forming a distinct subposterior depression anterior to margin. Lobe over spiracle protruding posterodorsally into pale calyptra; area above strongly depressed. Anteroventral cavity elongate. Faint metapleural median groove extending backward from midpoint of mesopleural sulca, posteroventrally, widening to nearly circular depression. From posterior margin a few poorly developed metapleural ridges extend anteriorly. The dorsalmost ridge (ridge 1 of Nordlander 1980), emerging just ventral to calyptral lobe, is slightly more well-developed, as is the one emerging from the posteroventral corner (ridge 3 of Nordlander 1980), directed obliquely anterodorsally. Ventral to these, a straight ventral carina is well elevated. Posteroventral corner rounded, with no obliquely posterolaterally facing surface, with the line of hairs along posterior margin commencing at the ventral beginning of the curve of the posteroventral angle. Propodeum protruding only in area of nucha in both lateral and dorsal view. Propodeal carinae high and stout, in posterodorsal view well separated and angled at midpoint. Propodeum densely hairy except on carinae, on nucha, on surface between carinae, and on posterolaterally facing surfaces immediately below spiracles.

Wings with hyaline surface and occasional dots, remnants of pubescence; males occasionally with setae in distal half of forewings. Forewing broad, apically rounded, with deep closed radial cell, 1st radial abscissa distinctly shorter than 2nd radial abscissa. Stout, erect setae or their remnant setigerous punctures visible on dorsal surface of subcosta. Submarginal and median veins visible as slight fold or lost completely. Hind wings with long cilia on posterior wing margin.

Legs reddish straw-colored to brown; not remarkably long. A small patch of woolly setae usually visible on posterioproximal surface of hind coxa.

Metasoma dominated by large tergite (fused tergites of 3rd and 4th metasomal segments), with complete hairy ring in anterior part and dense band of punctuation posteriorly, and a few posterior tergites more or less visible. Male metasoma shorter than mesosoma and about 3/4 as high as long, blunt, nearly squared posteriorly in lateral view. Female metasoma subequal in size to mesosoma; hypopygium projecting out very slightly.

Etymology. Striatovertex means striated vertex (from latin Stria and Ve r t ex), a characteristic property of representatives of this genus, and is feminine.

Biogeography: Widespread in the New World, also with one species in Australia, and one species deliberately introduced in Hawaii from North America (Kotinsky, 1906; Beardsley, 1989).

Biology: Collected throughout the year and apparently multivoltine, Striatovertex wasps are well-known to be associated with herbivore dung, as koinobiont parasitoids of calyptrate Diptera larvae-puparia therein. There are many literature records of rearings of Eucoila from cow dung in North America, which is usually a name under which Striatovertex is not distinguished from true Eucoila and from some species of Trybliographa. In some studies the wasps have been identified as Eucoila impatiens (Bruce, 1964; Thomas & Wingo, 1968; Turner et al., 1968; Wylie, 1973) or Eucoila near rufocincta (Wharton, 1979), in which case they are Striatovertex unless actually misidentified; while all the records given as Eucoila sp can be Striatovertex, Eucoila or Trybliographa (Blickle, 1961; Blume, 1970; 1986; Figg et al., 1982; Harris & Summerlin, 1984; Sanders & Dobson, 1966; Skoda et al., 1987). As long as the voucher specimens from these studies are not traced and identified, we can expect, based on our own faunistic knowledge, that a majority of large eucoilines in dung in the Nearctic are indeed Striatovertex but far from all, so that some of these records may in fact not concern Striatovertex. In these studies, Striatovertex impatiens has been recorded as common parasitoids of Haematobia irritans (Linnaeus, 1758) (the horn fly) and Musca autumnalis DeGeer, 1776 (the face fly) of Muscidae, and as rare from Neomyia cornicina (Fabricius, 1781) of Muscidae and Ravinia querula (Walker, 1849) of Sarcophagidae. In addition to this, Striatovertex rufocincta has been held in laboratory culture as a parasitoid of blowflies on carrion (Lindquist, 1936). Other indirect sources and label data record Striatovertex emerging from carrion and birdnests. It is probable that Striatovertex attack all kinds of large calyptrate fly larvae in rotting habitats, but substrate preferences, and the clues attracting the wasps, as well as frequency and success rate on different hosts of course remain to investigate with properly identified wasps.

Included species:

Striatovertex azteca (Cameron, 1905) n. comb. (Heptamerocera azteca Cameron, 1905, Pseudeucoila azteca [comb. by Weld, 1952]) Nearctic species.

Striatovertex cultra (Girault, 1920) n. comb. (Psilodora cultra Girault, 1920, Eucoila cultra [comb. by Weld 1952]) Nearctic species.

Striatovertex erythropa (Ashmead, 1888) n. comb. (Cothonaspis erythropa Ashmead, 1888, Psilodora erythropa [comb. in Kieffer, 1901], Eucoila erythropa [comb. by Weld 1951]) Nearctic species.

Striatovertex impatiens (Say, 1836) n. comb. (Diplolepis impatiens Say, 1836, Eucoila impatiens [comb. by Ashmead, 1885]) (syn. Kleidotoma cupulifera Provancher, 1881 [syn. by Ashmead, 1885]) Nearctic species (introduced on Hawaii).

Striatovertex incisa (Cameron, 1884) n. comb. (Eucoela incisa Cameron, 1884) Neotropical species.

Striatovertex insularis (Dalla Torre, 1892) n. comb. (Eucoela insularis Dalla Torre, 1892, replacement name for Eucoela rufiventris Cameron nec Giraud) Neotropical species.

Striatovertex nudipennis (Kieffer, 1907) n. comb. (Psilodora nudipennis Kieffer, 1907, Eucoila nudipennis [comb. by Weld, 1952]) (syn. Psilodora paraensis Kieffer, 1909 [syn. by Nordlander, 1981], syn. Psilodora paraensis var. festiva Kieffer, 1909 [syn. by Nordlander, 1981]) Neotropical species.

Striatovertex occipitalis (Kerrich & Quinlan, 1960) n. comb. (Eucoila occipitalis Kerrich & Quinlan, 1960) Australian species.

Striatovertex rubripes (Ashmead, 1887) n. comb. (Eucoila rubripes Ashmead, 1887) Nearctic species.

Striatovertex rufocincta (Kieffer, 1907) n. comb. (Eucoila rufocincta Kieffer, 1907, Pseudeucoila rufocincta [comb. by Weld, 1952]) (syn. Lytosema atricornis Kieffer, 1910 [syn. by Nordlander 1981]) Nearctic species.

Striatovertex septemspinosa (Gillette, 1891) n. comb. (Eucoila septemspinosa Gillette, 1891, Psilodora septemspinosa [comb. by Kieffer 1901]) Nearctic species.

Striatovertex unicolor (Kieffer, 1909) n. comb. (Eucoila unicolor Kieffer, 1909, Pseudeucoila unicolor [comb. by Weld 1952]) Neotropical species.

Striatovertex vagabunda (Ashmead, 1885) n. comb. (Kleidotoma vagabunda Ashmead, 1885, Eucoila vagabunda [comb. by Weld 1951]) Nearctic species.

Systematic position. Striatovertex are typical Ganaspini (of the "neotropical grade" group) in all the relevant characters (small hairpatches on coxae, high and emarginate pronotal plate, F1 modified in males), and lack the important characteristics of Eucoilini and the " Trybliographa complex" to which the true Eucoila belong (hairless metapleural triangle, distinct subalar pits, F2 modified in males).

Representatives of Striatovertex have been included in two recently made phylogenetic analyses, first the analysis of the subfamily Eucoilinae based on morphological characters by Fontal-Cazalla et al (2002) and then the combined analysis including molecular data of the whole family Figitidae by Buffington et al (2007). In the former, Striatovertex came out close to Epicoela and Aganaspis in the grouping proposed there as the "neotropical grade". In the latter, it was sister to Aganaspis but Epicoela were situated elsewhere, and the whole apparent "neotropical grade" turned out to be part of "core Eucoilinae " and of a monophyletic group therein which was called the " Zamischus group", which coincides with the tribe Ganaspini (as reerected in Forshage & Nordlander, 2008)

Morphologically, Striatovertex is clearly most similar to Aganaspis and Epicoela, and according to the analyses it is either the former or both of these it is most closely related to. Obviously, several other not closely-related genera of Eucoilinae and other Figitidae share important characters, in addition to the reduction of wing pubescence. Some of these attack hosts in dung and carrion too (the true Eucoila, plus several genera of Figitinae: Figites, Neralsia, Xyalophora, Xyalophoroides), while some others attack fruit-infesting tephritid or lonchaeid flies (Odontosema, Lopheucoila, Dettmeria) (Buffington, 2007 and references therein). Wing pubescence reduction has been commonly interpreted as an adaptation facilitating smooth movement in a sticky substrate, which would possibly make sense in dung as well as fruit. In some of these taxa, reduction of wing pubescence is more pronounced in females than males, which makes sense if related to oviposition habitat. Nevertheless, several other parasitic wasps including other Figitidae oviposit in these and other similarly sticky habitats with normally pubescent wings without apparent problems.