Xyela longula Dalman, 1819

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 : 55-58

Xyela longula Dalman, 1819

Xyela longula Dalman, 1819: 124–125 , ♀, type locality: Sweden, Vestrogothia [= Skaraborgs län or Älvborgs län].

Pinicola longula : André 1881: 468 (combination with Pinicola).

Xyelatana longula: Benson 1938: 34 (combination with Xyelatana ).

Xyelatana longula ssp. longula: Benson 1945: 36 (status changed).

Xyela piliserra C. G. Thomson, 1871: 317 , ♀, type locality: Sweden, Lapland; Blank 2002: 223 (junior synonym of longula ). Pinicola piliserra : André 1881: 468 (combination with Pinicola).

Xyelatana piliserra: Benson 1938: 34 (combination with Xyelatana ).

Xyelatana longula ssp. piliserra: Benson 1945: 36 (status changed).

Description. Female. Color. Head yellow with black and brown pattern: two black stripes along frontal furrows meeting black ocellar and postocellar area and black longitudinal spot in middle of frons always present ( Fig. 24 ); kidney-shaped spots on vertex usually separate from black postocellar area. Antennae brown. Thorax dorsally brown with more or less distinct pale pattern on pronotum, mesonotal lobes and mesoscutellum, tegulae pale, sometimes brown in middle, mesepisternum largely pale brown. Abdominal terga brown, lateral parts of terga 8 and 9+10 and distal sternum partly pale, valvifer 2 dark brown with pale base, membrane between valvifer 2 and valvula 3 and ventral edge in basal half of valvula 3 pale, valvula 3 brown ( Fig. 95 ). Legs pale brown, femora with dark longitudinal stripes, posterior coxae dark brown with distal 0.3–0.5 of ventral side pale. Wing membrane, venation and pterostigma brownish infuscate.

Morphology. Fore wing (4.1–) 4.7–5.7 mm long, 0.90–1.10 times longer than ovipositor sheath, either Rs+M (up to 100 µm) or 1r-m (up to 60 µm) present, usually 2r-m meeting Rs distal to the furcation of Rs1 and Rs2 (seldom interstitial and once observed proximal to furcation). Synantennomere 3 780–1050 µm long, antennomere 4 210–260 µm long and 6.0–7.0 times longer than wide distally. Article 3 of maxillary palp 250–330 µm long, 0.75–0.90 as long as scape and narrower than synantennomere 3. OOL: POL = 1.9–2.2(–2.3): 1. Ovipositor sheath (4.1–) 4.4–5.6 mm long, valvula 3 3.6–4.2 times longer than valvifer 2 and 13.5–16.5 times longer than wide at base ( Fig. 95 ). Valvula 3 of ovipositor sheath diamond-shaped in cross section, pale membranous area distally elongate but faintly delimited, valvula 3 distally narrowing to acicular tip, which bears no defined sensilla field, ventrally with ca 5 blunt setae ( Fig. 87 ). Ovipositor almost straight. Valvula 1 of ovipositor compressed, medial part parallelsided and longitudinally bicolorous (presumably due to different degree of sclerotization of dorsal and ventral portions), aulax terminating almost at tip, ventral edge sloping up to tip, with 9–10 wide-spaced annuli in distal 0.1 (basal 3 annuli only present close to aulax and distal continuous from aulax to ventral edge of valvula 1, basal oblique and distal 2–3 almost vertical), 6–7 serrulae, olistether with 6–9 setae ( Fig. 121 ). Valvula 2 dorsally smooth and parallel-sided with regular shallow notches with indistinct vertical annuli in distal half, notches not evidently related to evenly spread sensilla campaniformia, dorsal edge of left and right valvula fused for most of their length up to triangular rise at 0.9 of ovipositor length, distal 0.1 of valvula 2 tapering to tip, with ca 7–8 oblique annuli. Posterior tibia 0.95–1.20 mm long, all claws with delicate subapical tooth.

Male. Color. Similar to female. Coloration of face varying from extensively yellow ( Fig. 25 ) to predominantly brown. Hypopygium mostly yellow.

Morphology. Fore wing (3.7–)4.0– 4.7 mm long, either Rs+M (up to 100 µm) or 1r-m (up to 40 µm) present, usually 2r-m meeting Rs distal to the furcation of Rs1 and Rs2 (seldom interstitial). Synantennomere 3 (650–)850–910 µm long, antennomere 4 180–250 µm long and 6.0–7.5 times longer than wide distally. Article 3 of maxillary palp 230–280(–310) µm long, 0.70–0.90 times as long as scape and narrower than synantennomere 3. OOL: POL = 1.8–2.2: 1. Longitudinal apodeme of basiparamere straight-lined, basal portion in ventral position, harpe ca 0.6 times as long as wide in lateral view. Lower ergot on valvular stalk present. Valviceps 1.90–2.20 times longer than wide on medial lobe, without lateral lamella, proximal lobe of penis valve 0.12–0.17 times as long as valviceps and 0.90–1.00 times as high as medial lobe, excision on lower edge 0.16–0.23 as deep as width of medial lobe, valviceps on medial lobe 1.05–1.15 times wider than on distal lobe, 2 distal flagella present, tip of longer flagellum reaching 0.90–1.05 width of distal lobe ( Fig. 126 ). Valviceps without median longitudinal sclerotization, medial lobe broadly rounded, 7–17 cone-like sensilla present, upper edge between medial and distal lobe with dense pattern of setae. Posterior tibia (0.80–) 0.93–1.10 mm long, all claws with delicate subapical tooth.

Barcodes. GUID ABV4344 (1 larva).

Type material. Xyela longula . Lectotype ♀ (here designated): [bottom label adjacent to specimen, forwarded as image file by H. Mejlon:] “ Xyela longula Dalman [reference to Dalman’s original description:] act. H. 1819. 124. 2. ♀”; [on pin of specimen:] “♀”; “87.”; [red:] “Lectotype Xyela longula Dalman, 1819 det. S. M. Blank 2012”; “ Xyela longula Dalman, 1819 det. S. M. Blank 2012”. Left antenna and left fore wing missing, right antenna glued to cardboard label. UUZM, in box 304 of Gyllenhal’s collection.

Xyela piliserra . Lectotype ♀ (designated by Blank 2002): [small blue label]; “Lpl.” [= Lappland]; [large label with red margin, possibly a cabinet label:] “ piliserra ”; “1978 292”; [yellow:] “ ZML 1998 269”; [red:] “Lectotypus ♀ Xyela piliserra C. G. Thomson, 1871 des. S. M. Blank 1999”; “ Xyela longula Dalman, 1819 ♀ det. S. M. Blank 1999”. In perfect condition. MZLU.

Host plant. ● Pinus sylvestris L. (1 larva associated with imagines by barcoding analysis).

Biology. The earliest flight records in the season for X. longula are from the end of March ( Austria, North Tyrol, Zirler Berg , Martinswand ; Germany, Mecklenburg-Vorpommern, Teschendorf ). Judging from the data of collection material, imagines of X. longula are active about 10–20 days earlier than X. julii in Germany and Scandinavia. But an overlapping flight phenology might be expected (Tab. 5). Entwistle (1996) made similar observations in Great Britain: “My own records [of X. longula ] were 28 th March, 1994— one female; 1 st April, 1995— one female; 10 th April, 1994— one male. [...] Standardised weekly samples at Migdale Wood in 1995 showed X. julii imagines to be present from 16 th April to 23 rd May, peaking in about the first week of May (during the whole sample period a total of 525 X. julii imagines were collected).”

Geographic distribution. Austria, Czech Republic, Finland, France, Germany, Netherlands, Russia (Moskovskaya Oblast, Sankt Peterburg Oblast), Sweden, Switzerland ( Fig. 20 ). Additionally reported for Belgium and Luxembourg ( Magis 1994), Great Britain ( Harwood 1950, Entwistle 1996), Estonia ( Viitasaari et al. 1998), Hungary (Carpathian Basin; Zombori 1974), Latvia ( Tsinovskiy 1953).

Remarks. Females are distinguished from Xyela helvetica by the longer ovipositor (fore wing 0.90–1.10 times longer than ovipositor, 1.20–1.35 in X. helvetica ). Valvula 1 of the ovipositor is strikingly bicolorous in longitudinal direction.

All male Xyela specimens from Europe, which lack a lateral lamella on the penis valve, have so far been attributed to X. longula . One male from Tence ( France: Auvergne, MNHN) is tentatively identified as X. longula . The most striking difference is the presence of ca 30 cone-like sensilla on the medial lobe ( Fig. 127 ), while only 7–17 sensilla are present in X. longula . In addition this male differs in the 90–140 µm long vein 1r-m on the fore wing (either Rs+M present or 1r-m up to 40 µm long in X. longula ), and the proximal lobe of the penis valve being 0.20 times as long as the valviceps (0.12–0.17 in X. longula ). The collection site is close to those of X. lugdunensis , but the male of this species has a lateral lamella present on the valviceps ( Fig. 128 ). Association with X. helvetica is not supported since the present male was collected in the lowlands far outside the native, subalpine distribution range of the supposed host of X. helvetica , Pinus mugo .

The larva of X. longula , for which a full barcoding sequence could be obtained, is placed next to X. curva at an interspecific distance of 21.69 %. This larva was grouped in the same cluster as a female and a male of X. longula , from which respectively only 241 bp and 266 bp long sequences could be obtained ( Fig. 23 ).

The type of X. longula was deemed to be lost, because it was searched for in MZLU and NHRS ( Schedl 1978). But Dalman (1819) referred to “ Mus. Dom. Gyllenhal”, i.e., to the collection of L. Gyllenhal which today is preserved in UUZM. Dalman had several females on hand for his description (“Non nisi feminas vidi.”). Only one specimen is still available from UUZM, which here is designated as the lectotype. The morphological parameters of the lectotype fall within the variability range of the species called X. longula .

The synonymy of X. longula and X. piliserra was already supposed by Viitasaari (1980), who pointed out that “specialists know either X. longula or X. piliserra , but not both.” A lectotype for X. piliserra was designated by Blank (2002), who finally synonymized these two names. Benson’s (1938) statement that he examined “the type of X. piliserra C. G. Thomson, 1871 ” cannot be assessed as a lectotype designation. Benson neither gave indications on how to recognize this particular specimen, nor did he add any type or identification label.

Males and females of this species were associated with the help of specimens of both sexes found at the same collection site (e.g., 3♀ 3♂ at the Martinswand in North Tyrol, Austria) or within the same geographical range (e.g., Konow’s specimens from Fürstenberg and Teschendorf, Germany).

Under the names X. longula or X. piliserra this species has repeatedly been reported to be associated with P. sylvestris ( Harwood 1950, Crooke 1957, Rasnitsyn 1965 and personal communication, Schedl 1978, Entwistle 1996), and this pine species undoubtedly is the larval host. Xyela longula imagines were reported several times to have been collected from this pine. All known records of imagines originate from the distribution range of P. sylvestris , and this is the only available autochthonous pine species in the northern part of the distribution range (e.g., Finland, Sweden). Veli Vikberg (personal communication) extracted larvae from staminate cones of P. sylvestris . One of them was identified as X. longula genetically (see above).

Figures

FIGURE 20. Records of Xyela longula (49 specimens from 32 collection sites) and natural distribution of the host plant, Pinus sylvestris (solid line, combined from Mirov 1967, Sokolov et al. 1977 and Willis et al. 1998). Two additional records included from Scotland (Harwood 1950, Entwistle 1996). The question mark refers to a tentatively identified male from Tence (France: Auvergne; see text).

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.