Trichoniscus pusillus

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Trichoniscus pusillus
Trichoniscus pusillus.jpg
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Arthropoda
Class: Malacostraca
Superorder: Peracarida
Order: Isopoda
Suborder: Oniscidea
Family: Trichoniscidae
Genus: Trichoniscus
Species:
T. pusillus
Binomial name
Trichoniscus pusillus
Brandt, 1833  [1]
Synonyms   [2]
  • Itea laevis
  • Philougria celer
  • Spiloniscus elisabethae
  • Trichoniscus caelebs
  • Trichoniscus coelebs
  • Trichoniscus elisabethae
  • Trichoniscus rhenanus

Trichoniscus pusillus, sometimes called the common pygmy woodlouse, is one of the five most common species of woodlice in the British Isles. It is acknowledged to be the most abundant terrestrial isopod in Britain. [3] It is found commonly across Europe north of the Alps, and has been introduced to Madeira, the Azores and North America. [4]

Contents

Description

T. pusillus may be distinguished from other British woodlice chiefly by its small size, which reaches no more than 5 millimetres (0.2 in). [5] Its body is elongate and quite rounded in cross section, and typically purplish. [6] It may be separated from related species in North America by its eyes of three ocelli each, rather than the single ocellus in the eyes of its relative Hyloniscus riparius . [7]

Reproduction

There are two distinct reproductive strategies within the species Trichoniscus pusillus. Many populations are, like most metazoans, bisexual and reproduce sexually; in other cases, females reproduce parthenogenetically, creating clones of themselves. [8] The sexually reproducing form is diploid while the parthenogenetic form is triploid; [8] since parthenogenesis always produces females, males are always diploid and can only be produced by sexual reproduction.

The frequency of males in the population decreases from south to north (a latitudinal cline) and in increasingly open habitats, with no males observed in most of Scotland and Scandinavia, but more than 15% males in the Iberian and Apennine Peninsulas. [9]

The reproductive season lasts from March to September, and one to three breeding waves may be observed. Females are gravid for 4–5 weeks before releasing 4–18 mancae from the brood pouch. [10]

Ecology

Like other woodlice, T. pusillus eats decaying plant matter of various kinds, although only alder litter is capable of sustaining a stable reproducing population. [10]

Predators of T. pusillus include the common shrew Sorex araneus , lycosid and dysderid spiders, centipedes such as Lithobius variegatus and perhaps carabid beetles. [11]

Trichoniscus pusillus is susceptible to infection by isopod iridescence virus, or Iridovirus (Iridoviridae). This is first apparent as a blue sheen on the unpigmented underside of the animals, but soon spreads to give the entire exoskeleton a bluish iridescence. [12]

Classification

Several former subspecies of T. pusillus are now treated as separate species. These include Trichoniscus alticola , Trichoniscus baschierii , Trichoniscus provisorius , Trichoniscus noriucs and Trichoniscus pygmaeus . [2]

See also

Related Research Articles

<span class="mw-page-title-main">Isopoda</span> Order of arthropods

Isopoda is an order of crustacean, which includes woodlice and their relatives. Members of this group are called Isopods and include both terrestrial and aquatic species. All have rigid, segmented exoskeletons, two pairs of antennae, seven pairs of jointed limbs on the thorax, and five pairs of branching appendages on the abdomen that are used in respiration. Females brood their young in a pouch under their thorax.

<i>Porcellio scaber</i> Species of woodlouse

Porcellio scaber, is a species of woodlouse native to Europe but with a cosmopolitan distribution. They are often found in large numbers in most regions, with many species preying on them.

<i>Oniscus asellus</i> Species of woodlouse

Oniscus asellus, the common woodlouse, is one of the largest and most common species of woodlouse in the British Isles and Western and Northern Europe, growing to lengths of 16 mm and widths of 6 mm.

<i>Ligia oceanica</i> Species of woodlouse

Ligia oceanica, the sea slater, common sea slater, or sea roach, is a littoral zone woodlouse, living on rocky seashores of the European North Sea and Atlantic coastlines.

<i>Porcellio laevis</i> Species of woodlouse

Porcellio laevis is a species of woodlouse in the genus Porcellio. As the species epithet laevis as well as the vernacular name "swift woodlouse" suggests, the species is capable of quick bursts of speed when provoked.

<span class="mw-page-title-main">Woodlouse</span> Crustacean from the polyphyletic suborder Oniscidea

woodlouse is any crustacean belonging to the suborder Oniscidea within the order Isopoda. They get their name from often being found in old wood, and from louse, a parasitic insect, although woodlice are neither parasitic nor insects.

<i>Androniscus dentiger</i> Species of woodlouse

Androniscus dentiger, the rosy woodlouse or pink woodlouse is a species of woodlouse found from the British Isles to North Africa.

<i>Ligidium hypnorum</i> Species of woodlouse

Ligidium hypnorum is a species of woodlouse found across Europe and western Asia. It is a fast-moving, active species whichthat rarely grows longer than 9 mm (0.35 in). It is dark and shiny, and is similar in appearance to the common species Philoscia muscorum, and also the rarer Oritoniscus flavus. In Great Britain, it was first discovered at Copthorne Common, Surrey, in 1873, and most later records are also from South East England. It is considered a good indicator species for ancient woodland.

<i>Armadillidium pictum</i> Species of woodlouse

Armadillidium pictum is a species of woodlouse which occurs over most of Europe, except the Mediterranean Basin and Southeast Europe. In the British Isles, it is only known from a few sites, making it by some accounts, "Britain's rarest woodlouse". Since these sites are all remote from human habitation, in Cumbria and Powys, the species is thought to be native rather than introduced.

<i>Hemilepistus reaumuri</i> Species of woodlouse

Hemilepistus reaumuri is a species of woodlouse that lives in and around the deserts of North Africa and the Middle East, "the driest habitat conquered by any species of crustacean". It reaches a length of 22 mm (0.87 in) and a width of up to 12 mm (0.47 in), and has seven pairs of legs which hold its body unusually high off the ground. The species was described in the Description de l'Égypte after the French Campaign in Egypt and Syria of 1798–1801, but was first formally named by Henri Milne-Edwards in 1840 as Porcellio reaumuri. It reached its current scientific name in 1930 after the former subgenus Hemilepistus was raised to the rank of genus.

Reductoniscus costulatus is a species of woodlouse in the family Armadillidae. In the wild, R. costulatus has been found in Mauritius, the Seychelles and Hawaii, including the islands of Oʻahu and Kauaʻi and Hawaiʻi. It was discovered in the Palm House at the Royal Botanic Gardens, Kew in 1948, 1976 and 1988, and has been found in greenhouses across Europe.

<i>Ligia</i> Genus of woodlice

Ligia is a genus of isopods, commonly known as rock lice or sea slaters. Most Ligia species live in tidal zone cliffs and rocky beaches, but there are several fully terrestrial species which occur in high-humidity environments.

<i>Mesoniscus</i> Genus of woodlice

Mesoniscus is a genus of woodlice, placed in its own family, Mesoniscidae, and section, Microcheta. It contains two species – Mesoniscus alpicolus and Mesoniscus graniger – that live in Central and Eastern Europe, mostly in and around caves.

<i>Deto echinata</i> Species of woodlouse

Deto echinata, the horned isopod, is a species of air-breathing isopod, or woodlouse, in the family Detonidae. It inhabits seashores in southern Africa and on some oceanic islands.

<span class="mw-page-title-main">Cylisticidae</span> Family of crustaceans

Cylisticidae is a family of woodlice in the order Isopoda. There are at least 4 genera and more than 60 described species in Cylisticidae.

<i>Helleria brevicornis</i> Species of woodlice

Helleria brevicornis, the sole species of the monotypic genus Helleria, is a terrestrial woodlouse endemic to the islands and coastal regions of the northern Tyrrhenian sea. H. brevicornis is of interest due to its endemism, unique ecology and basal position in the suborder Oniscidea.

<i>Invertebrate iridescent virus 31</i> Species of virus

Invertebrate iridescent virus 31 (IIV-31), also known informally as isopod iridovirus, is a species of invertebrate iridescent virus in the genus Iridovirus. Oniscidea serve as hosts. Infection is associated with decreased responsiveness in the host, increased mortality, and most strikingly, the emergence of an iridescent blue or bluish-purple colour due to the reflection of light off a paracrystalline arrangement of virions within the tissues.

<i>Hawaiioscia</i> Genus of woodlouse

Hawaiioscia is a genus of woodlouse known from the Hawaii, Rapa Nui, and Costa Rica. The genus was originally described from Hawaii on the presence of four troglobitic species on separate islands. A species within this genus was then described from Rapa Nui which lacked troglobtic traits, but only persists in cave-dwelling relict populations. Surprisingly, another species was then described from along the Pacific Coast of Costa Rica.

<i>Porcellio hoffmannseggii</i> Species of woodlouse

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References

  1. "Trichoniscus pusillus Brandt, 1833". Integrated Taxonomic Information System.
  2. 1 2 Helmut Schmalfuss (2003). "World catalog of terrestrial isopods (Isopoda: Oniscidea) — revised and updated version" (PDF). Stuttgarter Beiträge zur Naturkunde, Serie A. 654: 341 pp.
  3. J. Phillipson (1983). "Life cycle, numbers, biomass and respiratory metabolism of Trichoniscus pusillus (Crustacea, Isopoda) in a beech woodland — Wytham Woods, Oxford". Oecologia . 57 (3): 339–343. Bibcode:1983Oecol..57..339P. doi:10.1007/BF00377178. PMID   28309361. S2CID   13591328.
  4. E. Hornung. "List of the Hungarian Terrestrial Isopod Fauna". Szent István Egyetem Állatorvos-tudományi Kar.
  5. "Woodlouse Wizard: an identification key". Natural History Museum . Retrieved November 8, 2010.
  6. "Trichoniscus pusillus". Encyclopaedia Tiscali. Archived from the original on December 1, 2008. Retrieved February 10, 2009.
  7. Arnold W. Norden (2008). "The terrestrial isopods (Crustacea: Isopoda: Oniscidea) of Plummers Island, Maryland". Bulletin of the Biological Society of Washington . 15 (1): 41–43. doi:10.2988/0097-0298(2008)15[41:TTICIO]2.0.CO;2. S2CID   83483162.
  8. 1 2 Bengt Christensen (1983). "Genetic variation in coexisting sexual diploid and parthenogenetic triploid Trichoniscus pusillus (Isopoda, Crustacea)". Hereditas . 98 (2): 201–207. doi: 10.1111/j.1601-5223.1983.tb00594.x . PMID   6874390. Archived from the original on 2013-01-05.
  9. Graham Bell (1982). The Masterpiece of Nature: The Evolution and Genetics of Sexuality. Cambridge University Press. p. 635. ISBN   0-85664-753-5.
  10. 1 2 Guido Kautz, Martin Zimmer & Werner Topp (2000). "Responses of the parthenogenetic isopod, Trichoniscus pusillus (Isopoda: Oniscidea), to changes in food quality". Pedobiologia . 44 (1): 75–85. doi:10.1078/S0031-4056(04)70029-3.
  11. S. L. Sutton (1970). "Predation on woodlice; an investigation using the precipitin test". Entomologia Experimentalis et Applicata . 13 (3): 279–285. doi:10.1007/BF00334313.
  12. H. Wijnhoven, M. P. Berg (1999). "Some notes on the distribution and ecology of Iridovirus (Iridovirus, Iridoviridae) in terrestrial isopods (Isopoda, Oniscidae)". Crustaceana . 72 (2): 145–156. doi:10.1163/156854099503249.