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Leiobunum

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Leiobunum
Temporal range: Jurassic–present
female L. rotundum
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Arthropoda
Subphylum: Chelicerata
Class: Arachnida
Order: Opiliones
Family: Sclerosomatidae
Genus: Leiobunum
C. L. Koch, 1839
Type species
Phalangium rotundum
Latreille, 1798
Species

See text

Diversity
c. 120 species

Leiobunum is a genus of the harvestman family Sclerosomatidae with more than 100 described species. Contrary to popular belief, they are not spiders, although they share a resemblance. They are arachnids, in the order Opiliones, harvestmen. Species in Leiobunum tend to have relatively long legs compared with other harvestmen, and some species are gregarious.

Body form

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The teguments are soft or subcoriaceous. The striae of the cephalothorax and of the three last abdominal segments are very distinct; those of the anterior segments are scarcely or not at all distinct. The anterior and lateral borders of the cephalothorax are smooth. The eye eminence is relatively small; smooth or, rarely, provided with small, slightly distinct, tubercles; widely separated from the cephalic border. Lateral pores small, oval, and marginal. Anal piece large, transverse-oval or semicircular, much wider than long, and much wider than the reflected borders of the eighth segment. Mandibles short, similar in the two sexes ; first joint furnished at the base below with an acute tooth. Palpi simple ; femur, patella, and tibia without any process and without projecting angles ; maxillary lobe provided at the base with two strong, conical teeth. Maxillary lobe of the second pair of feet very long, nearly straight from the base, not attenuated, directed mesad nearly horizontally, and united on the ventro-meson to the lobe from the opposite side without forming a sensible angle; the two together lightly arched on the cephalic border, and forming an even curve. Sternal piece large, slightly contracted between the fourth pair of coxae, gradually enlarging and obtusely truncate cephalad. The feet are very long and slender; tibia of the second pair with a few false articulations. Palpal claw denticulate.[1] Many Leiobunum species tend to form clusters of several, but some up to 1,000 and more individuals.

Invasive species in Europe

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Leiobunum spec. from the Netherlands
Leiobunum vittatum
Leiobunum aldrichi

An as yet undescribed species of Leiobunum was first found in the Netherlands in October 2004, although reports date back to at least 2002. Since then, it has been identified from Germany, Switzerland, and Austria. It is distinct from all known Central European species and was probably introduced. This species has a strong tendency to group together, most of the time protected from wind and direct sunlight, and stay in one place for weeks. They swarm out at night to hunt on their own. When disturbed, they move their bodies up and down in a fast, rhythmic motion, with individuals moving away from the disturbance. The first juvenile stages seem to live on the ground below rocks and debris. The largest observed aggregation counted 770 individuals.[2]

Species

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  • Leiobunum hiraiwai hiraiwai (Sato & Suzuki, 1939) (Japan)
  • Leiobunum hiraiwai fuji Suzuki, 1976 (Japan)
  • Leiobunum hiraiwai izuense Suzuki, 1976 (Japan)
  • Leiobunum hiraiwai longum Suzuki, 1976 (Japan)
  • Leiobunum hiraiwai shiranense Suzuki, 1976 (Japan)
  • Leiobunum ischionotatum ischionotatum (Dugès, 1884) (Mexico)
  • Leiobunum ischionotatum luteovittatum Roewer, 1912 (Mexico)
  • Leiobunum japanense japanense (Müller, 1914) (Japan)
  • Leiobunum japanense japonicum (Suzuki, 1940) (Japan, Korea, Taiwan)
  • Leiobunum japanense uenoi Suzuki, 1964 (Japan)
  • Leiobunum longipes longipes Weed, 1890 (USA – northern)
  • Leiobunum longipes aldrichi Weed, 1893 (USA – northern)
  • Leiobunum maximum distinctum Suzuki, 1973 (Japan)
  • Leiobunum maximum formosum Suzuki, 1976 (Taiwan)
  • Leiobunum maximum maximum Roewer, 1910 (China, Japan, Taiwan)
  • Leiobunum maximum yushan Suzuki, 1976 (Taiwan)
  • Leiobunum montanum montanum Suzuki, 1953 (Japan)
  • Leiobunum montanum sobosanum Suzuki, 1976 (Japan)
  • Leiobunum politum politum Weed, 1890
  • Leiobunum politum magnum Weed, 1893 (USA – Mississippi)

[see also Leiobunum albigenium Sorensen, 1911 (Syria)]

  • Leiobunum ventricosum ventricosum (Wood, 1870)
  • Leiobunum ventricosum hiemale (Weed, 1890) (USA – southeastern)
  • Leiobunum ventricosum floridanum Davis, 1934 (Florida)
  • Leiobunum vittatum vittatum (Say, 1821)
  • Leiobunum vittatum dorsatum Say, 1821 (USA -northern)
  • Leiobunum vittatum minor Weed, 1892 (USA – South Dakota)

References

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  1. ^ Weed, Clarence M., 1889: A descriptive catalogue of the Phalangiinae of Illinois. In: Bulletin of the Illinois State Laboratory of Natural History, Urbana, Ill., 3(5):81–82:
  2. ^ Wijnhoven et al. 2007
  3. ^ a b c d e f g h i j k "Leiobunum". GBIF. Archived from the original on 10 January 2023. Retrieved 4 May 2018.
  4. ^ "Leiobunum Genus Information". BugGuide.net. Archived from the original on 24 February 2023. Retrieved 4 May 2018.
  • Joel Hallan's Biology Catalog: Sclerosomatidae
  • Wijnhoven, Hay; Schönhofer, Axel L. & Martens, Jochen (2007): An unidentified harvestman Leiobunum sp. alarmingly invading Europe (Arachnida: Opiliones). Arachnol. Mitt. 34: 27–38. PDF Archived 16 September 2009 at the Wayback Machine
  • Kury, A.B. (2014). "Classification of Opiliones". National Museum of Brazil. Archived from the original on 12 November 2020. Retrieved 4 May 2018.
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