Xyela julii ( Brébisson, 1818 )

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 : 41-44

Xyela julii ( Brébisson, 1818)

Pinicola julii Brébisson [reported by Blainville], 1818: 117, ♂, type locality: Austria, Lower Austria, Hörweix near Etzen .

Xyela julii: Konow 1897: 57 (combination with Xyela )

Xyela pusilla Dalman, 1819: 124 , figs 1–11, ♂, type locality: Sweden, Uplandia and Vestrogothia [= Uppsala län, Västmanlands län, Skaraborgs län or Älvborgs län]; Lepeletier & Serville 1828: 792 (junior synonym of julii ).

Xyela henschii Mocsáry, 1912: 131 , ♂, type locality: Croatia, Krapina; Blank 2002: 222 (junior synonym of julii ).

Xyela henschi: Enslin 1918: 682 (misspelling).

Description. Female. Color. Head yellow with black and brown pattern: at least two black stripes along supraantennal furrows meeting black ocellar and postocellar area and longitudinal spot in middle of frons present, often dark pattern fusing to large dark sport of the frons; kidney-shaped spot on vertex often not confluent with black postocellar area ( Fig. 60 ). Antennae brown. Mesoscutum black with yellow pattern on medial half of lateral lobes, mesoscutellum with yellow spot. Mesepisternum pale except for brown dorsal, posterior and ventral margins. Abdominal terga brown, lateral parts of preapical terga, partly distal sternum, valvifer 2 and valvula 3 pale brown, membranous base of valvula 3 whitish, tip of valvula 3 darkened ( Fig. 109 ). Legs mainly pale brown, femora unicolorous pale, posterior coxae mainly dark brown. Wing membrane, venation and pterostigma pale brown.

Morphology. Fore wing 2.8–4.3 mm long, (1.60–)1.70–1.90 times longer than ovipositor sheath, vein Rs+M 180–280 µm long, 2r-m meeting Rs proximal to furcation of Rs1 and Rs2. Synantennomere 3 560–690 µm long, antennomere 4 130–160 µm long and 3.5–5.5 times longer than wide distally. Article 3 of maxillary palp 390–490 µm long, 1.45–1.65 times longer than scape and wider than synantennomere 3. OOL: POL = (1.30–)1.40–1.65(–2.00): 1. Ovipositor sheath (1.60–) 1.90–2.40 mm long, valvula 3 2.00–2.35 times longer than valvifer 2 and 6.5–8.0 times longer than wide at base ( Fig. 109 ). Valvula 3 of ovipositor compressed, pale membranous area about as long as basal width of valvula 3, dorsal edge of valvula 3 sloping down to round tip, distally with sensilla field exposed and directed caudally, bearing 3 setae. Ovipositor almost straight and compressed. Valvula 1 with aulax terminating distally, ventral edge sloping up to tip, with ca 15–16 oblique closely spaced annuli in distal quarter, without serrulae, olistether with 6 setae. Left and right valvulae 2 fused along dorsal edge in basal half. Valvula 2 with smooth dorsal margin, tapering in distal half, pale and evenly sclerotized, in distal 0.4 with single scattered sensilla campaniformia, in distal 0.1 with 5–6 oblique annuli. Posterior tibia 0.75–0.95 mm long, claws without subapical tooth.

Male. Color. Variability of coloration similar to female but usually paler (see Fig. 61 for color pattern of head), hypopygium brown to dark brown.

Morphology. Fore wing 3.1–3.7 mm long, Rs+M 75–250 µm long, 2r-m meeting Rs proximal to furcation of Rs1 and Rs2. Synantennomere 3 540–650 µm long, antennomere 4 140–170 µm long and 4.0–6.0 times longer than wide distally. Article 3 of maxillary palp 350–410 µm long, 1.35–1.55 times longer than scape and wider than synantennomere 3. OOL: POL = (1.30–)1.40–1.75: 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 absent. Valviceps 1.50–1.60(–1.70) times longer than wide on medial lobe, with distinct oblique lateral lamella, proximal lobe of penis valve 0.23–0.29 times as long as valviceps and 0.70–0.75 times as high as medial lobe, excision on lower edge 0.22–0.27 as deep as width of medial lobe, valviceps on medial lobe (1.10–)1.20–1.25 times wider than on distal lobe, 2 distal flagella present, tip of longer flagellum reaching 0.65–0.75 width of distal lobe ( Fig. 144 ). Valviceps with median longitudinal sclerotization present, medial lobe almost symmetric and broad, with 4–8 cone-like sensilla along upper edge and scattered on lateral surface, upper edge between medial and distal lobe with 8–12 setae. Posterior tibia 0.60–0.85 mm long, claws without subapical tooth.

Barcodes. GUID ABY6138 , AAJ9260 (5♀, 2 larvae)

Type material. Pinicola julii . Neotype ♀ (here designated): “A [= Austria]: Niederösterr. [= Niederösterreich, Lower Austria]: Hörweix ( Etzen ), 31.5.1996 Pinus sylvestris , em. 18.4.1998 leg. Ewald Altenhofer ”; “ Xyela julii ( Brébisson, 1818) det. S. M. Blank 2000”; [red:] “Neotypus ♀ Pinicola julii Brébisson, 1818 des. S. M. Blank 2001”. DEI.

Xyela pusilla . Unknown number of ♀ and ♂ syntypes from “Uplandia” (= historical province Uppland; = modern Uppsala län or Västmanlands län) and “Vestrogothia” (= historical province Västergötland; = modern Skaraborgs län or Älvborgs län). Type material lost .

Xyela henschii . Lectotype ♀ (designated by Blank 2002): “Dr. Hensch Krapina Cro.”; “ Xyela henschii Mocs. typ. det. Mocsáry”; [label with red margin:] “ Lectotypus ♀ Xyela Henschii Mocsáry, 1912 des. Zombori, 1976”; [label with red margin:] “ Paralectotypus ♂ Xyela Henschii Mocsáry, 1912 des. Zombori, 1976”; “ Xyela julii ( Brébisson, 1818) ♀ ♂ det. S. M. Blank 1999”. Lectotype missing both valvulae 3, otherwise in good condition. HNHM. Paralectotype: 1♂ on same mount as lectotype, genitalia glued to small slide, HNHM.

Host plant. Pinus cembra L. ( Schedl 1978), P. nigra ssp. nigra Arn. (1♂ reared, A.P. Rasnitsyn personal communication), P. x rotundata Link (2♀ 4♂ from 1 reared sample), ● Pinus sylvestris L. (105♀ 54♂ from 9 reared samples; = Ο P. hamata D.Sosn. from Caucasus), P. uncinata Ramond ( Pschorn-Walcher & Altenhofer 2000) .

Biology. In the lowlands and the mountainous regions of Central, West and East Europe , and in the high mountains of Greece (1,600–1,800 m altitude) imagines are active between mid-April and end May. In northern Finland and Sweden, they occur almost up to the North Cape from the end of May to the beginning of July (Tab. 5). For additional data see Blank (2002).

Geographic distribution. Austria, Belgium, Bulgaria, Croatia, Czech Republic, Denmark, Finland, France, Georgia (Abkhaszkaya Respublika), Germany, Great Britain Greece, Ireland, Italy, Mongolia, Netherlands, Norway, Poland, Russia (Irkutskaya Oblast, Moskovskaya Oblast, Murmanskaya Oblast, Respublica Gorno-Altay, Ryazanskaya Oblast, Sankt Peterburg Oblast), Slovakian Republic, Spain, Sweden, Switzerland, Turkey, Ukraine ( Fig. 17 ). Additionally reported from Estonia ( Viitasaari et al. 1998), Latvia ( Tsinovskiy 1953), Luxembourg ( Chevin & Schneider 1988). Zombori (1974) listed it for the Carpathian Basin but there is no material of X. julii in HNHM. Records of X. julii by Zirngiebl (1937) and Benson (1938) refer to a form similar to X. altenhoferi for North Africa and to X. variegata and X. tecta for Japan. The USNM holds a single female X. julii which was intercepted at a United States port among cargo on an aircraft from the Rhein-Main Airport in Frankfurt.

Remarks. Xyela julii is similar to the West Palearctic X. heldreichii , X. obscura and X. uncinatae and the East Palearctic X. pumilae in the shape of the valviceps with upper edge of proximal lobe almost parallel to the longitudinal axis, medial lobe symmetric, and longitudinal sclerotization apparent. Females of X. heldreichii , X. obscura and X. uncinatae have the head (at least predominantly) dark, whereas in the darkest X. julii females the face remains yellow at least along the eyes. Xyela pumilae differs in the infuscate wings and the different proportion of the ovipositor sheath. Males and females have been associated by study of extensive series reared from Pinus sylvestris .

Imagines of X. julii and X. obscura cannot be distinguished in the barcoding analysis ( Fig. 23 ). Accordingly, it is not possible to identify genetically their larvae extracted from Pinus mugo and P. sylvestris , but these fall within the same cluster as the imagines of the two species. Specimens of both X. julii and X. obscura are associated with two subclusters bearing the GUIDs ABY6138 and AAJ9260, but these subclusters remain unreproducible applying morphological approach. The intraspecific variability of X. julii is 2.34 % and of X. obscura 2.66 %. The nearest neighbor, X. graeca , is placed at a distance of 6.13%.

Both along altitudinal and geographical gradients the morphology of X. julii is rather stable. Usually material from the South is paler than that from the North. Females from Scandinavia often have the face predominantly black leaving only a narrow yellow line along the eye margin, whereas females from Spain, Irkutsk and Mongolia often have only dark brown to black stripes along the frontal furrows and the medial spot and the kidney-shaped spots more or less disconnected from the other dark pattern of the face.

Xyela julii is by far the most frequently cited xyelid in faunistic literature (see catalogue of Smith 1978). Its comparatively easy availability in the lowlands of Central and North Europe made it the favorite representative of the Xyelinae for comparative morphological studies and phylogenetic analysis of the lower Hymenoptera (e.g., Vilhelmsen 2001, Sharkey et al. 2012). Astonishingly the original description of Pinicola julii has not been reexamined seriously in comparison with the taxa which have been accepted as valid in the course of the past 70 years.

The Bulletin des Sciences par la Société Philomatique de Paris, which includes the original description of P. julii , is a rare journal, and it was possibly unavailable to most authors. Konow (1897) distinguished two European species, the strikingly different X. julii and X. longula . Enslin (1918) followed his opinion, although he expressed some doubt on the status of X. alpigena , X. graeca and X. henschi as synonyms with X. julii . Benson was the first who recognized X. alpigena , X. graeca and X. julii for certain among the European species. He added X. curva and published a key for the females ( Benson 1938). Later he separated the dark subalpine form X. obscura from X. julii , and he described X. menelaus ( Benson 1960) . Benson’s understanding of X. julii has generally been accepted by later authors (e.g., Rasnitsyn 1965, Schedl 1978, Zhelochovtsev & Zinovjev 1988, Blank 2002), although he never gave a reason for his decision relating the name Pinicola julii as described by Brébisson to a particular Xyela species.

If the characters given in Brébisson’s original description are considered alone, the identity of P. julii is doubtful. Among others the description characterizes the conspicuous antennae, the long article 3 of the maxillary palp (apparently the tiny article 1 was overlooked and article 3 therefore counted as the article 2), the presence of vein Rs+M (“trois cellules sous-marginales, la première reçoit la première nervure récurrente”), and for the female the long, compressed and darkened oviposition apparatus (“une longe et forte tarrière” and “la tarière est grise”). This encompasses the current understanding of both X. curva and X. julii . Valvula 3 of the ovipositor sheath is black to infuscate in X. curva and more or less infuscate in the preapical portion in X. julii . Other known European species can be excluded either by coloration, shape of ovipositor sheath, and / or known altitudinal and geographical distribution excluding the collection locality in northeastern France.

Brébisson described P. julii from Tour (near Falaise, Normandy, France). Neither Pinus sylvestris nor P. nigra are autochthonous to Normandy ( Mirov 1967, Willis et al. 1998), although we studied X. julii from several places in the lowlands of northern France. Xyela curva may be expected there on cultivated P. nigra . Brébisson collected Pinicola julii from resin trees (“arbres resineux”) and conifers in the first days of May, and he found it during a period of 15–20 days. This late phenology better fits a lowland population of X. curva than of X. julii .

The original description of P. julii was published under the name of the co-editor of the journal, H. de Blainville (signed by “Bv.”; see editorial board of the journal), but its title refers to “M. [= Monsieur] Brébisson”, who is the responsible person for nomenclatural matter (Art. 52.1 ICZN 1999). The work is generally assigned to the coleopterist Jean Baptiste Gilles de Brébisson (1760–1832) and not to his son Louis Alphonse de Brébisson (1798–1872), who became famous for his botanical work ( Constantin 1992). The collection of Brébisson was bought by A. Fauvel, given to Mrs B. Rancin and should have been forwarded to the ISNB later ( Dalibert 1927, Constantin 1992, Groll 2010). However, no relevant material could be located at the ISNB according to J.-L. Boevé (personal communication) and during our own study of the complete xyelids housed there. Accordingly the syntypes must be regarded as lost.

A neotype is necessary to ensure the unambiguous current and future use of the name Pinicola julii , because of the absence of original type material and due to conflicting evidence for the proper placement of P. julii from the data given in the original description. The neotype is selected for that Xyela species , which 1, infests Pinus sylvestris ; 2, which is the most abundant Central and North European Xyela species , and which has the widest distribution range among Xyela species ; and 3, which might be the most frequently cited name for a xyelid species still today (see references in Smith 1978). A specimen reared from Pinus sylvestris is hereby designated. The neotype agrees with the description above, which is covered by Brébisson’s characterization. It originates from the western part of the vast distribution range of X. julii as did the original syntypes.

Also the types of X. pusilla must be regarded as lost, because we could not locate concerning material in the NHRS, which includes J.W. Dalman’s collection. The original description, which was accompanied by excellent illustrations, leaves no doubt that X. pusilla agrees with X. julii . Only X. julii and X. longula are known from Scandinavia, and within this geographical context the long article 3 of the maxillary palp, the comparatively short ovipositor, and the well developed vein Rs+M on the fore wing (see Dalman’s [1819] figs 1a, 2a and 4) unequivocally indicate X. julii . Therefore, the current synonymy, first proposed by Lepeletier & Serville (1828), is considered correct.

Pinus sylvestris is well known to be the host plant of X. julii (e.g., Rasnitsyn 1965). The types of X. pusilla were collected in a P. sylvestris wood ( Dalman 1819). Rudow (1912) supposed that he had reared X. julii from enlarged shoots of P. sylvestris with swollen buds, but obviously his sample contained not only buds infested by the moth Rhyacionia buoliana (Denis & Schiffermüller, 1775) (Tortricidae) but also staminate cones with Xyela larvae. Over 140 subspecies, varieties or forms of P. sylvestris have been described, but besides the type var. sylvestris only var. hamata C. Steven (Balkan peninsula, N Turkey, SW Transcaucasia) and var. mongolica Litvinov ( Mongolia, NW China, S Siberia) are now normally accepted ( Earle 2011). All these forms are relevant as larval host plants. A female from Georgia was caught on “ P. hamata ” according to its labeling. Records from the Baikal region are inside the range of var. mongolica .

Pinus sylvestris exhibits the largest distribution area among pines, reaching from Scotland almost up to the Pacific Coast in Siberia, from Norway to Spain and from Arctic Siberia to Mongolia. Xyela julii apparently follows up to the limits of its host plant’s distribution range. In northern Europe, it was collected in vast number almost up to the North Cape. It is abundant in Scotland, where a P. sylvestris population became isolated some 4,400 years ago ( Willis et al. 1998), and later spread from there over England apparently along with cultivated trees. The most southern West Palearctic records of X. julii are from Spain (El Ventorillo) and northern Greece (Mt. Kajmakčalan and Mt. Vrondou), where it was found between 1,480 –1,680 m altitude, and from Georgia (Caucasus National Park). In southern Siberia it occurs in the Altai Mountains (reported as X. obscura by Rasnitsyn 1965), where P. sylvestris grows between 350–700 m altitude ( Mirov 1967), and it was collected several times by Verzhutskij in the environs of Irkutsk (see also Verzhutskij 1966). The most southeastern record is from Mongolia (Hentiyn Nuruu, Bogdo ul).

The exceptional occurrence of X. julii on P. nigra might possibly have been caused by coinciding host plant phenologies similar to the occurrence of X. graeca on P. sylvestris . Pschorn-Walcher & Altenhofer (2000) reared X. julii from P. x rotundata , but they erroneously quoted P. uncinata for “Moor-Spirke” (see X. uncinatae for nomenclature of the pines). Pine and reared material have here been checked. Today this pine is mostly considered a variety or subspecies of P. sylvestris , which mainly differs in resin chemistry ( Mirov 1967, Earle 2011). Development on P. cembra as assumed by Schedl (1978) cannot be confirmed. This relationship is very unlikely due to restriction of P. cembra to the subalpine zone of the central Alps, where X. julii is absent.

Figures

FIGURE 17. Records of Xyela julii (2094 specimens from 356 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).

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 42–65. Color pattern of head of Xyela species: X. curva group, X. rasnitsyni group, X. julii group (part). Legend: HT—holotype; NT—neotype; PT—paratype.

FIGURES 105–120. Ovipositor sheaths of Xyela species. All figures at same scale. Legend: HT—holotype; NT—neotype; PT—paratype.

FIGURES 136–145. Penis valves of Xyela species: X. curva group, X. julii group (part). Figs 138–139 and 141 reproduced from Blank et al. (2005).