Xyela alpigena ( Strobl, 1895 )

Blank, Stephan M., Shinohara, Akihiko & Altenhofer, Ewald, 2013, <strong> The Eurasian species of <em> Xyela </ em> (Hymenoptera, Xyelidae): taxonomy, host plants and distribution </ strong>, Zootaxa 3629 (1), pp. 1-106 : 19-20

Xyela alpigena ( Strobl, 1895)

Pinicola alpigena Strobl, 1895: 277–278 , ♂, type locality: Austria, Styria, Rottenmanner Tauern, environs of Scheibelsee [= Scheiplsee]; Konow 1897: 58 (junior synonym of julii ).

Xyela alpigena: Enslin 1918: 682 (combination with Xyela ).

Description. Female. Color. Head yellow with black pattern: two black stripes along supraantennal furrows 2–5 times wider than ocellar diameter, meeting black ocellar and postocellar area, black longitudinal spot in middle of frons always present; kidney-shaped spots on vertex often fusing with stripes along supraantennal furrows ( Fig. 28 ), sometimes separated by small yellow gap. Antenna black, a little paler below. Thorax dorsally black, more or less brown or yellow on pronotum, mesonotal lobes and mesoscutellum, tegula pale and infuscate in middle, mesepisternum largely pale brown to yellow. Abdominal terga dark brown, lateral parts of terga 8 and 9+10 paler and 2 preapical sterna more or less pale brown, valvifer 2 pale brown basally and dark distally, membrane between valvifer 2 and valvula 3 white, valvula 3 black with small white ventral margin extending up to preapical region (often indistinct, Fig. 97 ). Legs pale brown, femora usually with infuscate longitudinal stripes, posterior coxae dark brown with distal 0.3–0.5 pale ventrally. Wing membrane slightly infuscate, venation and pterostigma pale brown.

Morphology. Fore wing 4.5–4.8 mm long, 1.90–2.05 times longer than ovipositor sheath, vein Rs+M 0–100 µm long, seldom 1r-m present and 0–60 µm long (e.g., in lectotype), 2r-m meeting Rs proximal to furcation of Rs1 and Rs2. Synantennomere 3 810–960 µm long, antennomere 4 240–260 µm long and 6.5–7.5 times longer than wide distally. Article 3 of maxillary palp 540–600 µm long, 1.70–1.80 times longer than scape and distinctly wider than synantennomere 3. OOL: POL = 1.70–2.00: 1. Ovipositor sheath 2.25–2.50 mm long, valvula 3 1.75–1.95 times longer than valvifer 2 and 7.0–8.0 times longer than wide at base ( Fig. 90 , 97 ). Valvula 3 of ovipositor sheath wedge-shaped, in distal third diamond-shaped in cross section, pale membranous area distally extending up to preapical region as small ventral pale margin, valvula 3 distally narrowing to small round tip, distally with sensilla field sunk and directed laterally, bearing 9 setae ( Fig. 91 ). Ovipositor indistinctly bent downwards. Valvula 1 of ovipositor compressed, aulax terminating preapically, ventral edge sloping up to tip, with 3 vertical and 3–4 oblique annuli in distal 0.05 of ovipositor length, 5–6 serrulae, olistether with ca 4 setae. Left and right valvulae 2 fused along dorsal edge up to distal 0.15. Valvula 2 evenly tapering toward tip, in distal 0.15 with 4–5 teeth, in preapical 0.6 with 7–9 irregularly spaced groups of 2–3 sensilla campaniformia surrounded by dense sclerotization protruding roundly from dorsal edge of valvula 2, in between groups additional single sensilla campaniformia ( Fig. 122 ). Posterior tibia 1.00– 1.15 mm long, all claws with delicate subapical tooth.

Male. Color. Dark pattern less extensive, e.g., stripes along frontal furrows often narrower than diameter of ocellus and more or less interrupted ( Fig. 29 ), scape, pedicel and synantennomere 3 pale brown, posterior coxae predominantly pale, hypopygium completely pale, preceding sterna more or less pale.

Morphology. Fore wing 3.8–4.3 mm long, Rs+M 0–120 µm long, seldom vein 1r-m present and 0–50 µm long, 2r-m usually meeting Rs proximal to furcation of Rs1 and Rs2, seldom fusing with Rs2 0–40 µm distal of furcation. Synantennomere 3 740–930 µm long, antennomere 4 260–330 µm long and 7.5–10.0 times longer than wide distally. Article 3 of maxillary palp 430–550 µm long, 1.40–1.50 times longer than scape and distinctly wider than synantennomere 3. OOL: POL = 1.65–1.90: 1. Longitudinal apodeme of basiparamere curved, basal portion in lateral position, harpe about as long as wide in lateral view. Lower ergot on valvular stalk present ( Fig. 129 ), sometimes small ( Fig. 3 ). Valviceps 1.40–1.50 times longer than wide on medial lobe, lateral lamella vertical with proximal and distal edge s-shaped, proximal lobe of penis valve 0.18–0.22 times as long as valviceps and 0.98–1.05 times as high as medial lobe, excision on lower edge 0.11–0.15 as deep as width of medial lobe, valviceps on medial lobe 1.55–1.70 times wider than on distal lobe, 2 (exceptionally 3) distal flagella present, tip of longer flagellum reaching 0.80–0.90 width of distal lobe ( Figs 3 , 129 ). Valviceps without median longitudinal sclerotization (seldom valviceps slightly infuscate longitudinally), medial lobe broad and slightly truncate on upper edge and evenly sloping down to distal lobe, with dense group of 22–30 cone-like sensilla along upper edge and on lateral surface, upper edge between medial and distal lobe with dense pattern of setae. Posterior tibia 0.95–1.10 mm long, claws with delicate subapical tooth.

Barcodes. GUID ABU9234 (1♀, 3 larvae).

Type material. Pinicola alpigena . Lectotype ♀ (designated by Blank 2002): [green label:] “ Xyela sp. alpigena [...; illegible Gabelsberg stenography] 26/5 90 ”; [label added by G. Morge, green handwriting:] “22”; “ Xyela alpigena (Strobl) ♀ det. W. Schedl 1971”; [red:] “Lectotypus ♀ Pinicola alpigena Strobl, 1895 des. S. M. Blank 1999”; “ Xyela alpigena (Str.) ♀ det. S. M. Blank 1999”. Head missing. NMBA. Paralectotype: 1♂ (= X. obscura ) labeled “ Xyela alpigena Str. ♂ Scheiplsee 26/5 90 ” and Morge’s label “23”, NMBA.

Host plant. ● Pinus cembra L. (16♀ 12♂ from 3 reared samples, 3 larvae identified by barcoding), P. koraiensis Sieb. & Zucc. ( Schedl 1978, 1980, cited as P. “ koraensis ”), P. peuce Grisebach ( Blank 2002) , P. strobus L. ( Benson 1962).

Biology. See Blank (2002).

Geographic distribution. Austria, Germany, Switzerland. Additionally recorded from Italy, from the Aosta Valley ( Casale & Pesarini 1976), Trentino ( Coslop & Masutti 1979) and from South Tyrol ( Hellrigl et al. 1996) ( Fig. 8 ). The record from Bulgaria by Taeger (1987) refers to X. peuce ( Fig. 8 ). Published records for the East Palearctic and Nearctic are based on Benson’s (1962) erroneous synonymy of X. brunneiceps Rohwer, 1913 , X. kamtshatica ( Fig. 9 ), and X. middlekauffi Burdick, 1961 with X. alpigena , but actually X. alpigena is restricted to the European Alps (and possibly the neighboring Carpathian mountains).

Remarks. See Xyela peuce for differentiation from other representatives of the alpigena group. The four specimens of X. alpigena included in the barcoding analysis display an intraspecific variation of 0.46 % and are placed at an interspecific distance of 11.29 % to the next neighbor, X. curva ( Fig. 23 ).

Strobl (1895) supposed that Xyela alpigena might live on Pinus cembra which was here confirmed by rearing. In the barcoding analysis a female of X. alpigena and three larvae extracted from P. cembra were grouped at short distance within the same cluster ( Fig. 23 ). Benson (1961, 1962) considered X. alpigena to be Holarctic with X. brunneiceps , X. kamtshatica , and X. middlekauffi as synonyms. He considered Pinus strobus as a host of X. alpigena , which Burdick (1961) had reported for X. middlekauffi . Schedl (1980) added P. koraiensis , which Rasnitsyn (1965) had listed for X. kamtshatica . However, material similar to X. alpigena from the Nearctic and the East Palearctic regions belongs to several, morphologically different species ( X. brunneiceps , X. middlekauffi , X. kamtshatica , X. koraiensis , X. sibiricae , X. ussuriensis ). Specimens mentioned by Blank (2002) from Bulgarian stands of Pinus peuce belong to X. peuce .

Figures

FIGURE 8. Records of Xyela alpigena (51 specimens from 22 collection sites) and X. peuce (21 specimens from 5 collection sites) and natural distribution of the (supposed) host plants, Pinus cembra (solid line) and P.peuce (dashed line, both according to Willis et al. 1998).

FIGURE 9. Records of the East Asian Xyela species supposedly feeding on Pinus (Strobus) species: X. kamtshatica (21 specimens from 4 collection sites), X. pumilae (4 specimens from 2 collection sites) and X. sibiricae (8 specimens from 2 collection sites). Additional record of X. kamtshatica by Takeuchi (1938) included for Hokkaido. The rhomb-shaped symbol represents records of X. koraiensis, X. rasnitsyni and X. ussuriensis supposedly feeding on Pinus koraiensis (illustrated separately in Figs 10, 22). Legend for natural distribution of Pinus species: P. koraiensis (solid line, according to Mirov 1967), P. pumila (dotted line) and P.sibirica (dashed line, both combined from Sokolov et al. 1977 and Kremenetski et al. 1998).

FIGURE 23. Barcoding analysis of Xyela species. The tree is primarily based on specimens for which COI sequences longer than 600 bp and including less than three ambigous nucleotides could be obtained. Some shorter sequences have been added to associate sexes or larvae with imagines. Each specimen is labelled as follows: “Xyela ...”—species name; “DEIGISHym ...”—unique identification number of specimen in DEI collection; “Male / Female”—sex, larva if no sex is indicated; e.g., “661” / “603” / “658” ...—base pairs [bp] sequence length; “[0n] / [1n] / [2n]”—0–2 ambiguous nucleotides included in sequence; e.g., “Austria, Karnten [= Kärnten, Carinthia]”—country and province of origin of specimen; “BOLD: ...”—globally unique identifier (GUID). The label “Xyela 005 P. sabiniana sp.” refers to larvae obtained from Pinus sabiniana which here are identified as X. bakeri.

FIGURES 24–41. Color pattern of head of Xyela species: X. longula group, X. lugdunensis group, X. alpigena group, X. meridionalis group. Legend: HT—holotype; LT—lectotype; PT—paratype. Legend for Fig. 25: kss—kidney-shaped spot; mfs—medial frontal spot; sff—stripe along frontal furrow.

FIGURES 95–104. Ovipositor sheaths of Xyela species. All figures at same scale. Legend: HT—holotype; PT—paratype.

FIGURES 86–94. Ovipositor sheath, sensilla pattern and sensilla plate (spl) at the apex of the ovipositor sheath. 86, Xyela helvetica. 87, X. longula, arrows indicate the modified hairs at apex of valvula 1. 88, X. lugdunensis. 89, X. meridionalis. 90–91, X. alpigena. 92–93, X. curva. 94, X. densiflorae.

FIGURES 121–125. Distal section of ovipositors. 121, Xyela longula. 122, X. alpigena. 123, X. occidentalis (paratype). 124, X. curva. 125, X. rasnitsyni (paratype). Arrowheads in Figs 123–124 indicate preapical small tooth on dorsal edge of valvula 1.

FIGURES 126–135. Penis valves of Xyela species: X. longula groups, X. lugdunensis group, X. alpigena group, X. meridionalis group. 127, tentatively identified male of from Tence (France: Auvergne, MNHN), see text. 128, paratype of X. nigroabscondita.

FIGURES 2–5. Measurements and terminology of wing venation (see explanations on pp. 8–10). 2, Xyela rasnitsyni (paratype), ovipositor sheath (embedded in glycerine and therefore valvula 3 a little wider compared to dry, pinned specimens). 3, X. alpigena, penis valve. 4, X. curva, wings. 5, X. lugdunensis (paratype of X. nigroabscondita), fore wing.