Euura amentorum

Euura amentorum (Förster, 1854)

Figures 3, 4, 14A–C, 18A, 20B, D–F, 21A–C

Nematus amentorum Förster, 1854: 332–334. Described: syntypes, 5♀. Published type locality: Gegend von Crefeld [Germany, Krefeld area]. Lectotype designated below.

Pristiphora amentorum: Konow, 1905; Enslin 1916.

Amauronematus amentorum: Conde, 1938.

Pontopristia amentorum: Lindqvist, 1953.

Amauronematus (Pontopristia) amentorum: Liston, 1995.

Euura amentorum: Prous et al., 2014.

Nematus (Pontopristia) amentorum: Zhelohovcev, 1988.

Nematus suavis Ruthe, 1859: 308. Described: syntypes, 2♀ (NHMW, examined). Published type locality: Island [Iceland]. Lectotype designated below. Synonymy with amentorum by Lindqvist (1961).

Amauronematus suavis: Konow, 1901.

Pontopristia suavis: Malaise, 1921.

Nematus laevigatus Zaddach, 1883 [in Brischke 1883]: 194–195. Described: holotype ♀ (probably destroyed). Published type locality: not stated.

Pontania atra Marlatt, 1896: 24 (key), 37. Described: holotype ♀ (USNM, examined). Published type locality: Michigan [probably East Lansing, Michigan [USA]: Zinovjev & Smith 1999]. Secondary homonym in Euura of E. atra (Jurine, 1807). Synonymy with amentorum by Conde (1938).

Pontania maura Rohwer, 1908: 47. Described: syntype (s), ♀ (USNM, not examined). Published type locality: Florissant, Colorado [USA]. Synonymy with amentorum by Conde (1938).

Pontania amentivora Rohwer, 1915: 209. Described: syntypes, 4♀ (USNM, not examined). Published type locality: Falls Church, Virginia [USA]. Synonymy with amentorum by Conde (1938).

Amauronematus amentivorus: Benson, 1960a.

Pristiphora amentorum var. nigripleuris Enslin, 1916: 528 (key), 533. Described: syntypes, ♀ (ZSM, examined). Published type locality: not stated. Lectotype designated below.

Pontopristia kamtchatica Malaise, 1931: 53–54. Described: syntypes, 9♀. Published type locality: Klutchi, Petropawlowsk and Nischne-Kamtchatsk (See Aszabatch [Lake Azhabachye]) [Russia, Kamchatka]. Lectotype designated below. Synonymy with amentorum by Benson (1962).

Nematus (Pontopristia) kamtchaticus: Zhelohovcev, 1988

Diagnosis. Female: Specimens with pale interantennal area, outer orbit, pronotum, and parts of mesepisternum (Fig. 3C, J), are easily distinguished from all the other species, in which these parts are entirely black. Dark E. amentorum specimens differ from all other species, except E. freyja, in the distally wider valvulae 3, in dorsal view 1.8–2.1 × as wide as narrowest distal width of metatibia (at most 1.6 × as wide in other species). E. amentorum differs from E. freyja in its largely pale forewing stigma and costa (blackish in E. freyja) and stouter body shape.

Male: So far, only pale coloured males are known, which differ from other amentorum group males in their pale malar space, interantennal area, pronotum, and part of mesepisternum (Fig. 3F, K). Penis valve (Fig. 18A): The apical extension of pseudoceps is much longer than that of any other known male in the amentorum group, and in this respect resembles only a few other Euura species: E. abnormis (Holmgren), E. cornuta (Lindqvist), and E. longicauda (Hellén).

Description. Female. Length 3.5–5.5 mm. Black. Pale are at least more or less mandibles, palps, labrum, tibiae, and apices of femora. Cerci pale. Wing veins including fore wing pterostigma and costa pale (Fig. 3A); margins of stigma sometimes darker.

Head. In dorsal view moderately contracted behind eyes, and length posterior of eye about 0.40 × length of eye (Fig. 3G–H). Mostly dull with coriaceous sculpture except for labrum. Upper head densely setose; setae pale, about 0.7 × as long as anterior ocellus diameter. Clypeus subtruncate to slightly emarginate medially, labrum apically rounded (Fig. 3I–J). Antenna (Fig. 3D) 0.95–1.10 × as long as fore wing costa (Fig. 3A).

Thorax. Pronotum, tegula and mesoscutum densely punctate, dull. Mesoscutum sparsely punctate, with shiny interspaces. Vestiture similar to upper head, but shorter, adpressed. Lateral mesoscutal lobe approximately 1.50 × as long as greatest width. Mesoscutellum as broad as long, without longitudinal median furrow; with few, extremely weak punctures; smooth and shiny, to dull with fine sculpture. Mesepisternum smooth, shiny; without a ventral glabrous patch; setae about 1.0 × as long as diameter of anterior ocellus.

Abdomen. Valvulae 3 in lateral view clearly orientated upwards; apically narrow, rounded (Fig. 4D). In dorsal view 1.8–2.1 × as wide as narrowest distal width of metatibia, strongly expanding towards tip (Fig. 4B). Cercus reaches approximately to the tip of valvulae 3. Lancet (Fig. 14A–C): 16–19 [most frequently 17] annular sutures; moderately curved; lamnium with rather flat marginal serrulae; basal annular sutures without ctenidial teeth. Base of tangium with prominent, narrow lobe.

Male [three specimens examined, all from Finland]. Length 3.5–4.5 mm. All are extensively pale-coloured (Fig 3F). Antenna (Fig. 3K) 1.05–1.10 × as long as fore wing costa; slightly tapering towards apex. Abdominal tergum 8 (Fig. 4E–F): posterior edge of procidentia subrectangular to rounded, tergal hollows reach almost to base of tergum. Penis valve (Fig. 18A): Extension of pseudoceps longer than height of paravalva; paravalva upper surface almost flat.

Variability. Colour pattern of females highly variable. The palest European females (e.g. Fig. 3C, H, J) have pale scape, pedicel, underside of base of flagellum, whole face below top of toruli including clypeus and labrum, outer orbit, temple, nearly whole pronotum, whole tegula, central parts and / or underside of mesepisternum, legs except for tarsi and extreme base of coxae, all abdominal sterna, broad lateral parts of terga, cercus, and sawsheath. The darkest specimens (e.g. Fig. 3A–B, G, I) have only the following pale: apices of femora; base, apex and underside of tibiae, cercus. Pale specimens occur apparently throughout the species’ European range, but the very dark specimens are only known from subarctic and arctic regions. The extant type series of four female P. kamtchatica exhibits colour variability comparable to the European material: the lectotype is the palest and largest (5.5 mm), and NHRS-HEVA000006353 is the darkest and smallest (4.5mm). The size and shape of the lancet serrulae are also somewhat variable in both European specimens and those from Kamtchatka (Fig.14A–C). Lindqvist (1961) wrote that the lancet of E. amentorum has 18 annular sutures, but we found this to be rather variable: 16–19 sutures in 75 examined specimens. So far, only males with extensive pale markings are known. Two of these (http://id.luomus.fi/GP.110189 (Fig. 3E–F), DEI-GISHym12665), have entirely pale hind legs, and are thus even paler than the palest females. Sclerotisation of tergum 8 (Fig. 4E–F) is highly variable, and the apparent outline of the procidentia varies correspondingly.