Xyelidae

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Xyelidae
Temporal range:
Ma[1]
Megaxyela sp. from Oklahoma
Xyela, the type genus of Xyelidae, from British Entomology
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Superfamily: Xyeloidea
Newman, 1834
Family: Xyelidae
Newman, 1834
Genera

See text

The Xyelidae are a comparatively species-poor family of

living fossils
since they represent one of the oldest lineages of insects and include still extant forms.

The extant species occur in the Northern Hemisphere, especially in

Oriental species. Two genera and about 15 species occur in Europe.[5][6] Considering additional fossil records from Australia,[7] South Africa[8] and Argentina,[9] the extant species display a relict
distribution. The species in the subfamily Xyelinae are associated with
Ulmus
).

The family is characterized by the appendages of the head, which are remarkable in that the antennae and palpi are nearly leg-like in structure, with a long basal segment followed by a series of tiny segments, as in the tibia-tarsus.

Description

Imago (Adult)

Xyelidae are small Hymenoptera. Most species are 3 to 5 mm long, but species of

ontogenetic fusion of several antennal articles, and it is unique among the extant Hymenoptera species. In Pleroneura, Xyelecia and most species of Xyela the maxillary palps are strongly enlarged and bear specialized setae on the distal articles. The wing venation is the most complete among Hymenoptera: Only in Xyelidae the radial sector Rs furcates into the veins Rs1 and Rs2, while in other Hymenoptera Rs1 is absent. The females bear a more or less long ovipositor, which in some species of Xyela may be as long as the body. Morphology of the ovipositor and the ovipositor sheath are important characters for identification to species level. The penis valves of the males are densely setulous, which is a rare character state among the basal lineages of Hymenoptera. Females and males mate with the bodies directing in opposite direction. In Xyelinae the genital capsule of the males are revolved for 180° after disclosure from the pupal skin (strophandry). Macroxyelinae are orthandrous after emergence. They mate in the same position as Xyelinae, but the male genital capsule is rotated yet in course of mating (facultative strophandry).[10]

Larva

Like in many other sawflies, the

stemma) on each side, which is reduced in mining species, and short antennae comprising five articles. The thorax bears short legs comprising three articles. Unlike the larvae of all other Hymenoptera and Lepidoptera which lack prolegs
on at least the first abdominal segment, larvae of Xyelidae have prolegs on all abdominal segments. In free feeding Xyelidae (Macroxyela, Megaxyela) the abdominal prolegs are conspicuous and consist of two articles, while in the mining species (Pleroneura, Xyela) they are reduced to inconspicuous transverse bulges.

Pupa

Unique among the Hymenoptera, the

Trichoptera and in the basal lineages of Lepidoptera.[15][16][17]
The Hymenoptera excluding Xyelidae are characterized by immobile adecticous pupae.

Ecology

The larvae of all Xyelidae are phytophagous and associated with trees. Larvae of the comparatively species-rich Xyela live inside the growing staminate cones of pines and feed on the sporophylls and the pollen. The North American Xyela gallicaulis is exceptional in causing galls on fresh shoots of some pine species, inside which the larva feeds.[18] Larvae of Pleroneura feed inside young shoots of firs. Only the Japanese Pleroneura piceae is associated with spruce.[19] Larvae of Macroxyelinae are free feeders of deciduous tree species. The two North American species of Macroxyela feed on elms, the East Asian and North American species of Megaxyela on Juglandaceae like walnuts, hickory and wingnuts.[20][21][22] For Xyelecia nearctica an endophagous life style and an association with firs is supposed.[23]

Many species of Xyelidae are host specific, with only a single larval host plant known.

Monophagy is the prevailing life style in most species of Xyela.[24][25] For this genus, the date of oviposition is closely correlated with the development of the staminate cones of the host pines, which might prevent a host shift in many cases. For some North American species of Xyela the association with each several species of pines (oligophagy) has been reported in literature,[14] but supposedly such records are often based on taxonomic problems to separate morphologically similar species of Xyela properly.[6] Through molecular access, true oligophagy could be demonstrated recently for Xyela bakeri (associated at least with Pinus contorta, Pinus ponderosa and Pinus sabiniana)[26] and Xyela brunneiceps (associated with Pinus flexilis and Pinus strobiformis).[27] Lack of reliable, reproducible host data could cause inaccurate reports of monophagy or oligophagy in many taxa of Xyelidae, but at least some of the species included in Megaxyela and Pleroneura are truly oligophagous.[22][28]

After completing feeding, Xyelidae larvae dig into the ground and form an earthen cell, where they usually spin a cocoon and develop into a pupa. Absence of a cocoon has been observed in Megaxyela togashii from Japan.[12] The imago emerges in the following spring to mate. Subsequently, the female deposits eggs with the ovipositor. In most species of Xyela, the tip of valvula 3 of the ovipositor sheath is equipped with specialized sensory structures called sensilla trichodea and sensilla campaniformia, which are involved in the oviposition process.[13][25][27] In Pleroneura, unlike practically all other Hymenoptera, the hard and conical ovipositor sheath is used in addition to the ovipositor proper to penetrate the resinous buds of firs.[13] Megaxyela gigantea and most other species of Megaxyela has strikingly long hind legs which are used to fold a newly growing leaf to provide shelter for their eggs which are fixed with glutinous material between on the upper sides of the folded leaf.[29][21][12]

Many species of Xyelidae facultatively

European Alps.[30][13][25]

Adults of Xyela are pollen feeders of a variety of plants, which bear flowers with easily accessible pollen (e.g.,

Salix).[14][25] The enlarged maxillary palps of most Xyela (and supposedly also of Pleroneura and Xyelecia) serve for the extraction of pollen from the flowers.[14][6]

Although they feed upon often economically important tree species, Xyelidae are usually of only small significance as pest organisms. Pleroneura piceae damages the growth of

Sakhalin spruce, since the larvae destroy the young shoots.[31] Larvae of Megaxyela major (and supposedly also of Megaxyela langstoni) feed on leaves of pecan and are regarded as a pest of pecan plantations in the Southeastern USA.[32][33][34][22]

Systematics and taxonomy

Xyelidae represent the most basal lineage of Hymenoptera and very likely the

phylogenetic analyses of both morphological characters and DNA sequences.[35] The great age of the family is supported by numerous fossil records. All Hymenoptera recorded from the Triassic are classified as Xyelidae, while representatives of other hymenopterous families have been found no earlier than the Jurassic. During the Mesozoic and the Tertiary, the Xyelidae obviously were much more species-rich and more widely distributed than today. Thus, the comparatively few extant species can be regarded a relict
group.

Extant taxa

Macroxyela sp. from Ontario

The Electronic World Catalog of Symphyta[2] provides a complete account of the valid extant genera and species, their synonyms, the concerning references to original descriptions and distribution data on the level of countries and provinces.

The European species can be identified with help of „The Western Palaearctic Xyelidae“ of Blank (2002),[13] all Eurasian species of Xyela with Blank et al. (2013).[25] The North American Macroxyelinae were revised by Smith & Schiff (1998),[20] the North American species of Xyela by Burdick (1961),[14] the North American species of Pleroneura by Smith et al. (1977),[28] the East Asian species of Megaxyela by Shinohara (1992),[21] the East Asian species of Pleroneura by Shinohara (1995),[19] and the species of Megaxyela of the World by Blank et al. (2017).[22]

Extinct taxa

The Electronic World Catalog of Symphyta[2] provides a complete account of the valid fossil genera and species, their synonyms and the concerning references to original descriptions.

Genus without classification into a subfamily of Xyelidae

†Archexyelinae

    • †Archexyela Riek, 1955, 2 fossil species
    • †Asioxyela Rasnitsyn, 1964, 4 fossil species
    • †Dinoxyela Rasnitsyn, 1969, 1 fossil species
    • †Euryxyela Rasnitsyn, 1964, 1 fossil species
    • †Ferganoxyela Rasnitsyn, 1969, 2 fossil species
    • †Leioxyela Rasnitsyn, 1969, 5 fossil species
    • †Lithoxyela Rasnitsyn, 1969, 1 fossil species
    • †Madygenius Rasnitsyn, 1969, 2 fossil species
    • †Moltenia Schlüter, 2000, 1 fossil species
    • †Oryctoxyela Rasnitsyn, 1969, 2 fossil species
    • †Triassoxyela Rasnitsyn, 1964, 3 fossil species
    • †Xaxexis Pagliano & Scaramozzino, 1990 [= Euryxyela Hong, 1984], 1 fossil species
    • †Xiphoxyela Rasnitsyn, 1969, 2 fossil species
    • †Xyelinus Rasnitsyn, 1964, 2 fossil species

Macroxyelinae

†Madygellinae

Xyelinae

References

  1. PMID 27958352
    .
  2. ^ a b c Taeger, A., Liston, A.D., Prous, M., Groll, E.K., Gehroldt, T. & Blank S.M. 2018: ECatSym – Electronic World Catalog of Symphyta (Insecta, Hymenoptera). Program version 5.0 (19 Dec 2018), data version 40 (23 Sep 2018). Senckenberg Deutsches Entomologisches Institut (SDEI), Müncheberg.
  3. ^ "ITIS". Integrated Taxonomic Information System. 2020. Retrieved 5 March 2020.
  4. ^ a b Taeger, A.; Blank, S.M.; Liston, A.D. 2010: World Catalog of Symphyta (Hymenoptera). Zootaxa 2580: 1-1064.
  5. ^ Taeger, A., Blank, S.M. & Liston, A. D. 2006: European Sawflies (Hymenoptera: Symphyta) – A Species Checklist for the Countries. Pp. 399-504. In: Blank, S.M., Schmidt, S. & Taeger, A. (eds): Recent Sawfly Research: Synthesis and Prospects. Goecke & Evers, Keltern.
  6. ^ a b c d e f Blank, S.M. 2002: Biosystematics of the extant Xyelidae with particular emphasis on the Old World taxa (Insecta: Hymenoptera). Dissertation, Freie Universität Berlin.
  7. ^ Riek, E. F. 1955: Fossil insects from the Triassic beds at Mt. Crosby, Queensland. Australian Journal of Zoology 3: 654-690.
  8. ^ Schlüter, T. 2000: Moltenia rieki n. gen., n. sp. (Hymenoptera: Xyelidae?), a tentative sawfly from the Molteno Formation (Upper Triassic), South Africa. Paläontologische Zeitschrift 74(1/2): 75-78.
  9. ^ Lara, M. B., Rasnitsyn, A. P. & Zavattieri, A. M. 2014: Potrerilloxyela menendezi gen. et sp. nov. from the Late Triassic of Argentina: The Oldest Representative of Xyelidae (Hymenoptera: Symphyta) for Americas. Paleontological Journal 48(2): 182-190.
  10. ^ Schulmeister, S. 2001: Functional morphology of the male genitalia and copulation in lower Hymenoptera, with special emphasis on the Tenthredinoidea s. str. (Insecta, Hymenoptera, 'Symphyta'). Acta Zoologica 82: 331-349.
  11. ^ Dyar, H.G. 1898: Description of an unusual saw-fly larva belonging to the Xyelinae. Psyche 8(265): 212-214.
  12. ^ a b c Shinohara, A., Hara, H., Kramp, K., Blank, S. M. & Kameda, Y. 2017: Bird droppings on chestnut leaves or sawfly larvae: DNA barcodes verify the occurrence of the archaic Megaxyela togashii (Hymenoptera, Xyelidae) in Hokkaido, Japan. Zootaxa 4221(2): 220-232.
  13. ^ a b c d e f g Blank, S.M. 2002: The Western Palaearctic Xyelidae (Hymenoptera). Pp. 197-233. In: Viitasaari, M. (ed.): Sawflies (Hymenoptera, Symphyta) I. A review of the suborder, the Western Palaearctic taxa of Xyeloidea and Pamphilioidea. Tremex, Helsinki. (read online)
  14. ^ a b c d e f Burdick, D.J. 1961: A taxonomic and biological study of the genus Xyela Dalman in North America. University of California Publications in Entomology 17(3): 285-355.
  15. ^ Weber, H. & Weidener, H. 1974: Grundriß der Insektenkunde. G. Fischer, Stuttgart, Studienausgabe, 640 pp.
  16. ^ Naumann, I. D. (ed.) 1991: The Insects of Australia. Melbourne Univ. Press, Carlton 1-2: 1-1137
  17. ^ Scoble, M.J. 1995: The Lepidoptera. Form, function and diversity. Nat. Hist. Mus., London and Oxford Univ. Press, Oxford et al., 404 pp. (reprint with corrections)
  18. ^ Yates, H.O. III & Smith, D.R. 2009: History, Distribution, Damage, and Life Cycle of a Pine Shoot Gall Sawfly, Xyela gallicaulis (Hymenoptera: Xyelidae). Journal of Entomological Science 44: 276-283.
  19. ^ a b c Shinohara, A. 1995: The Sawfly Genus Pleroneura (Hymenoptera, Xyelidae) in East Asia. Japanese Journal of Entomology 63(4): 825-840
  20. ^ a b c d Smith, D. R. & Schiff, N. M. 1998: The genera Macroxyela Kirby and Megaxyela Ashmead (Hymenoptera: Xyelidae) in North America. - Proceedings of the entomological Society of Washington 100(4): 636-657.
  21. ^ a b c d Shinohara, A. 1992: The Sawfly Genus Megaxyela (Hymenoptera, Xyelidae) in East Asia. Japanese Journal of Entomology 60(4): 783-796.
  22. ^
    doi:10.5852/ejt.2017.348
  23. ^ a b Smith, D. R. 1964: Description of the Male of Xyelecia nearctica, with Comments on the Genus (Hymenoptera: Xyelidae). Pan-Pacific Entomologist 40(1): 54-56.
  24. ^ Blank, S.M., Shinohara, A. & Byun, B.-K. 2005: The East Asian Xyela species (Hymenoptera: Xyelidae) associated with Japanese Red Pine (Pinus densiflora; Pinaceae) and their distribution history. Insect Systematics & Evolution 36: 259-278.
  25. ^ a b c d e f g Blank, S.M., Shinohara, A. & Altenhofer, E. 2013: The Eurasian species of Xyela (Hymenoptera, Xyelidae): taxonomy, host plants and distribution. Zootaxa 3629: 1-106 PDF (Abstract).
  26. ^
    doi:10.11646/zootaxa.4303.1.6
  27. ^ a b c Blank, S.M. & Kramp, K. 2017: Xyela davidsmithi (Hymenoptera, Xyelidae), a New Pine Catkin Sawfly with an Unusual Host Association from the Sierra Nevada. Proceedings of the Entomological Society of Washington 119: 703- 717.
  28. ^ a b c Smith, D.R., Ohmart, C.P. & Dahlsten, D.L. 1977: The fir shoot-boring sawflies of the genus Pleroneura in North America (Hymenoptera: Xyelidae). Annals of the Entomological Society of America 70: 761-767.
  29. ^ Saito, K., 1941: [Ein dendro-entomologischer Beitrag.] (In Japanese.) Bull. agric. For. Coll. Suigen, (6): 1-235.
  30. ^ Pschorn-Walcher, H. & Altenhofer, E. 2000: Langjährige Larvenaufsammlungen und Zuchten von Pflanzenwespen (Hymenoptera, Symphyta) in Mitteleuropa. Linzer biologische Beiträge 32(1): 273-327
  31. ^ Hara, H. 1996: Akaezomatsu no shin gaichu marunaginatahabachi. (In Japanese). [Pleroneura piceae, a new pest of Picea glehnii.] Shinrin Hogo [= Forest Protection] 254: 25-26.
  32. ^ Ree, B. 2012. Insects. Texas Pecan Pest Management Newsletter 12 (1): [1–3].
  33. ^ Ree, B. 2014. Sawfly. Texas Pecan Pest Management Newsletter 14 (2): [1–3].
  34. ^ Ree, B. 2016: Insects. Texas Pecan Pest Management Newsletter 16 (2): [1–3]. PDF
  35. doi:10.1111/j.1096-0031.2011.00366.x
  36. doi:10.11646/zootaxa.4121.4.9
  37. doi:10.3931/e-rara-7221
  38. ^ Smith, D.R. 1990: A new Xyela (Hymenoptera: Xyelidae) from western United States. Entomological News 101: 9-12.
  39. ^ Togashi, I. 1972: Discovery of the genus Xylelecia Ross (Hymenoptera, Xyelidae) from Japan. Kontyû 40: 87-89.
  40. ^ Shinohara, A. 1998: Collection records of two rare xyelid sawflies (Hymenoptera, Symphyta) in Japan. Japanese Journal of Systematic Entomology 4: 389-390.
  41. ^ Smith, D.R. 1967: A review of the larvae of Xyelidae, with notes on the family classification (Hymenoptera). Annals of the Entomological Society of America 60: 376-384.
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