Ground lice

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Ground lice
Systematics
Class : Insects (Insecta)
Subclass : Flying insects (Pterygota)
Superordinate : New winged wing (Neoptera)
Order : Ground lice
Family : Ground lice
Genre : Ground lice
Scientific name of the  order
Zoraptera
Silvestri , 1913
Scientific name of the  family
Zorotypidae
Silvestri , 1913
Scientific name of the  genus
Zorotype
Silvestri , 1913

The ground lice (Zoraptera) are one of the smallest orders of insects . The 40 or so recent species and most of the 10 or so known fossil species of this taxon have all been assigned to the family Zorotypidae and the genus Zorotype . Ground lice form sub-social colonies from numerous associated adults and larvae. They live mainly in the tropics, a few species penetrate subtropical and occasionally temperate latitudes.

features

Ground lice are small insects, they reach a body length of 1.5 to 2.5 millimeters. All species come in two morphs : a few individuals have eyes and wings; these serve to expand and establish new colonies; after finding a place for a new colony, they shed their wings. The majority of individuals are wingless and eyeless and never leave the underground hiding places. The animals of the winged mophe are brown to black in color, those of the wingless morphs are more or less unpigmented and whitish in color. The animals are hairy relatively densely.

The relatively large head is roughly triangular in top view and roughly as wide as it is long, it is slightly drooping, the mouthparts point downwards (orthognath). Winged animals have compound eyes , these are moderately large with strikingly large ommatidia , and there are also three ocelles . The animals of the wingless morphs are completely eyeless. The clypeus of the head capsule is divided into a transparent anteclypeus and a postclypeus, which is narrowed towards the rear and which merges into the frons without a seam . It is narrowed by the antenna pits, which are close together, they are separated from each other less than their diameter. The antennae are thread-shaped and consist of nine limbs, they are about as long as the head and thorax combined. The labrum is retractable on the mouth parts. The chewing-biting mandibles are toothed at the top, in the basal section they have a wide chewing surface (molar region), and there is a flexible, finger-shaped appendix (prostheca). The last link of the palpitations of the maxilla and labium is greatly elongated and densely covered with sensory hair.

At the trunk section, the prothorax is slightly smaller than the head, it is larger than the middle mesothorax , and the posterior metathorax is the smallest section. The pronotum is relatively large and saddle-shaped drawn down on the sides, it is rounded and rectangular in plan view. The long and slender legs are designed as walking legs. The thighs are thickened, they have a row of bristles that cooperate with a similar row on the rails. The tarsus consists of two limbs with two claws. In winged specimens, the front wings are noticeably larger than the hind wings. The veining of the wings is greatly reduced, the forewings only have two longitudinal arteries and are equipped with a powerful pterostigma , the smaller rear wing only contains a forked longitudinal artery. The wing surface is hairy and ciliate on the edge, the base of the wing is petiolate.

The abdomen is cylindrical and connects broadly and without constriction to the trunk section, it consists of eleven segments, the rear of which are very small. On each side of the ninth tergite there is a small, one-part cercus . In the male, the tergites eight to eleven are transformed in a complex manner depending on the species, they serve as copulatory organs during mating. In females, the eighth sternite forms a subgenital plate, the ovipositor has regressed.

Characteristics typical of the order ( autapomorphies ) are the one-part cerci of both sexes and the lack of a laying pipe ( ovipositor ) in the female. The dimorphism between winged and wingless morphs is also rated as autapomorphism.

Zorotypus similar to a superficial observation dust lice with whom they are not closely related.

Way of life

All species are saprophages , they mainly feed on fungal tissue ( mycelia ) and spores . In addition, they opportunistically utilize other food sources such as dead arthropods. In addition, they are believed to be predators of small arthropods such as mites, and it has been observed in the laboratory how they are quite effective at hunting springtails . They live under the bark of dead trees ( dead wood ), often in galleries or cavities that were originally created by wood-eating species such as termites . They form small colonies that comprise 15 to 120 individuals and nymphs and are located where sunlight cannot reach them. Coexistence in colonies seems to be beneficial for the animals, solitary animals usually perish quickly. Mutual grooming is widespread, but not other social behavior such as feeding each other or helping with raising youngsters. During copulation, the male transmits a large spermatophore , which both serves as a food supply for the female and is intended to prevent other males from later mating. Females of the ground lice lay relatively few, but very large eggs, the diameter of which is almost the same as that of the female's abdomen. The eggs take about 6 to 9 weeks to develop. In the neotropical zorotype gurneyi both bisexual and all-female populations have been found; these multiply through (thelytoke) parthenogenesis . The first nymphs are eyeless with eight-limbed antennae. Later nymphs with and without wing sheaths appear next to each other. It will go through three to five stages, according to the few observations available in one to two months. The adults apparently live for a few months. The production of winged animals should start when the living conditions in the colony, e.g. B. by lack of food worsen.

distribution

Ground lice live exclusively in the tropics and subtropics , with both America and Asia being colonized. Some oceanic islands, also very isolated ones like the Galapagos, Hawaii, Fiji and Mauritius each have their own species. The northernmost occurrences reach as far as Tibet and the USA. The northernmost populations of the American Zorotype hubbardi , as far as Indiana, Iowa and Illinois, could be dependent on heaps of sawdust with internal heat generation from the rotting process. Although species have been found in New Zealand and New Britain , evidence from Australia is still lacking.

Systematics

The ground lice were only rediscovered and described by Filippo Silvestri in 1913 after he discovered the first species Zorotype guineensis in Ghana . Since he initially only had wingless animals, he named them from ancient Greek zoros (pure, unmixed), a- (without) and pteros (wing) Zoraptera, ie "the purely wingless".

The position of the ground lice in the insect system is largely unclear. The numerous contradicting attempts to sort the group into the system have even led to the expression "Zoraptera problem". The widespread opinion sees the tarsus spiders as the sister group . This group of insects, which is also restricted to warm climates and is largely unknown, shares a multitude of characteristics with the ground lice, including anatomical characteristics of the wings, colony life and the appearance of winged and wingless morphs. This grouping receives strong support from the special structure of the wing joint, which is only common to these two groups. Hennig follows in 1953, the Klausnitzer that zorotypus the other hand, represent the sister group to the Acercia combined groups ( booklice , louse , thrips and Hemiptera ) constitute and form with them the Paraneoptera . They share with them as common features (possible synapomorphies ) a fusion of the abdominal ganglia chain and a reduction of the Malpighian vessels and the tarsal limbs. In contrast to the ground lice, however, these groups are characterized by the absence of cerci and the transformation of the mouthparts into a lancing device. The grouping with the Paraneoptera is also supported due to the anatomy of the head. On the basis of a meta-analysis of various morphological investigations, the ground lice are in turn more closely related to cockroaches , termites and fishing frights . Molecular biological investigations based on the comparison of homologous DNA sections see the Zoraptera as a sister group of the family circle of the Polyneoptera . A new genetic analysis identified the Dermaptera (earwigs) as a sister group, with which they would stand together at the base of the Polyneoptera.

Within the ground lice, around 40 species are distinguished, which so far have all been assigned to a single genus. In the following table (as of 2004) all known species are listed. A number of other species have since been re-described.

Types of ground lice

Michael S. Engel introduced a subgenus Octozoros for some Cretaceous fossil species . Other editors also differentiate between their own genres. Engel and Grimaldi established a separate genus for a Cretaceous species with numerous plesiomorphic features, Xenozorotype burmiticus .

Revision by Kočárek, Horká and Kundrata 2020

In a 2020 revision of the Zoraptera, based on a new analysis of the morphological and genetic characteristics of most species, these authors propose a new systematics for the group in which the previous family Zorotypideae and the genus Zorotypeus are split up. The newly circumscribed family Zorotypidae and the new family Spriralizoridae can be distinguished morphologically on the basis of the structure of the male reproductive organs. These are symmetrical in the Spiralizoridae, and strongly asymmetrical in the Zorotypidae. Within the Zorotypidae they differentiate for a new genus Spermozoros , which includes a number of oriental species, as well as a monotypical subfamily Spermozorinae.

The following system would result:

  • Family Zorotypidae
    • Subfamily Zorotypinae
      • Genus Zorotype Silvestri, 1913, with the species Zorotype guineensis Silvestri, 1913; Zorotype asymmetristernum Mashimo, 2019; Zorotype delamarei Paulian, 1949; Zorotype vinsoni Paulian 1951; Zorotype shannoni Gurney, 1938; Zorotype amazonensis Rafael & Engel, 2006; Zorotype caxiuana Rafael, Godoi & Engel, 2008. Afrotropic (incl. Madagascar), Neotropic
      • Genus Usazoros Kukalova-Peck & Peck, 1993, with the only species Usazoros hubbardi (Caudell, 1918). Nearctic (North America).
    • Subfamily Spermozorinae Kočárek, Horká & Kundrata 2020
      • Genus Spermozoros Kočárek, Horká & Kundrata 2020 with the species Spermozoros asymmetricus (Kočárek, 2017), Spermozoros medoensis (Huang, 1976), Spermozoros weiweii (Wang, Li & Cai, 2016), Spermozoros impolitus (Mashimo, Engel, Dallai, Beutel Machida 2013), Spermozoros huangi (Yin & Li, 2017), Spermozoros sinensis (Huang, 1974). Orientalis: China, Malaysia, Indonesia.
  • Family Spiralizoridae Kočárek, Horká & Kundrata 2020
    • Subfamily Latinozorinae Kočárek, Horká & Kundrata 2020
      • Genus Latinozoros Kukalova-Peck & Peck, 1993, with the species Latinozoros barberi (Gurney, 1938) and other, as yet undescribed species. Neotropic, including Central America.
    • Subfamily Spiralizorinae Kočárek, Horká & Kundrata 2020
      • Genus Spiralizoros Kočárek, Horká & Kundrata 2020, with the species Spiralizoros cervicornis (Mashimo, Yoshizawa & Engel, 2013), Spiralizoros caudelli (Karny, 1922), Spiralizoros hainanensis (Yin, Li & Wu, 2015), Spiralizoros magnashimo , Engel , Dallai, Beutel & Machida, 2013), Spiralizoros silvestrii (Karny, 1927), Spiralizoros ceylonicus (Silvestri, 1913), Spiralizoros philippinensis (Gurney, 1938), Spiralizoros buxtoni (Karny, 1932). Orientalis: China, Vietnam, Malaysia, Indonesia (Kalimantan, Sumatra, Java), Sri Lanka, Philippines.
      • Genus Centrozoros Kukalova-Peck & Peck, 1993, with the species Centrozoros snyderi (Caudell, 1920), Centrozoros cramptoni (Gurney, 1938); Centrozoros Gurneyi (Choe, 1989); Centrozoros Hamiltoni (New, 1978); Centrozoros mexicanus (Bolívar y Pieltain, 1940); Centrozoros neotropicus (Silvestri, 1916); Centrozoros manni (Caudell, 1923). Nearctic and Neotropical.
      • Genus Brazilozoros Kukalova-Peck & Peck, 1993, with the species Brazilozoros brasiliensis (Silvestri, 1947), Brazilozoros weidneri (New, 1978), Brazilozoros huxleyi (Bolívar y Pieltain & Coronado, 1963). Neotropic (Brazil, Peru, Guyana, Ecuador).

A number of previously described, little-known species have not yet been assigned to one of the new genera.

It remains to be seen whether the new system will establish itself in science.

Fossil record

Ground lice have been found in amber since the early Cretaceous . The representatives of that time already looked very similar to today's ground lice, so that most of them have been placed in the recent genus Zorotype. They also occurred in two morphs and were only found in tropical regions, so that it is assumed that the ground lice have hardly changed in the millions of years that have passed since then. Since ambers with insect inclusions from ages earlier than chalk are almost never found, it is unknown when this group of animals first appeared.

supporting documents

  1. ↑ a b c d e f Y. Mashimo, Y. Matsumura, R. Machida, R. Dallai, M. Gottardo, K. Yoshizawa F. Friedrich, B. Wipfler, RG Beutel (2014): 100 years Zoraptera — a phantom in insect evolution and the history of its investigation. Insect Systematics & Evolution 45 (4): 371-393. doi: 10.1163 / 1876312X-45012110
  2. ↑ a b c Rolf G. Beutel, Frank Friedrich, Si-Qin Ge, Xing-Ke Yang: Insect Morphology and Phylogeny. Walter de Gruyter, Berlin and Boston 2014. ISBN 978-3-11-026263-6 . Chapter 6.13 Zoraptera, p. 257 ff.
  3. ↑ Order Zoraptera ( Memento from May 11, 2008 in the Internet Archive ) at faunistik.net the smaller rear wing contains only a forked longitudinal artery.
  4. ↑ a b Bernhard Klausnitzer: Zoraptera, ground lice. In Westheide, Rieger (Hrsg.): Special zoology part 1: single-cell and invertebrate animals. Gustav Fischer Verlag, Stuttgart, Jena 1997; Pages 646-647.
  5. ↑ Michael S. Engel (2007): The Zorotypidae of Fiji (Zoraptera). Fiji Arthropods VII. Edited by Neal L. Evenhuis & Daniel J. Bickel. Bishop Museum Occasional Papers 91: 33-38.
  6. ^ Garland T. Riegel (1963): The Distribution of Zorotypus hubbardi (Zoraptera). Annals of the Entomological Society of America, Volume 56, Number 6: 744-747.
  7. ↑ a b Rolf Georg Beutel & Daniela Weide (2005): Cephalic anatomy of Zorotypus hubbardi (Hexapoda: Zoraptera): new evidence for a relationship with Acercaria. Zoomorphology 124: 121-136. doi : 10.1007 / s00435-005-0117-z
  8. ↑ Michael S. Engel: Zoraptera In: Tree of Life Web Project, accessed July 23, 2009.
  9. ↑ Kazunori Yashizawa (2007): The Zoraptera problem: evidence for Zoraptera + Embiodea from the wing base. Systematic Entomology 32 (2): 197-204.
  10. ^ Ward C. Wheeler, Michael Whiting, Quentin D. Wheeler, James M. Carpenter: The Phylogeny of the Extant Hexapod Orders. Cladistics 17, 2001; Pp. 113-169. ( PDF ).
  11. ↑ Benjamin Wipfler, Harald Letsch, Paul B. Frandsen, Paschalia Kapli, Christoph Mayer, Daniela Bartel, Thomas R. Buckley, Alexander Donath, Janice S. Edgerly-Rook, Mari Fujita, Shanlin Liu, Ryuichiro Machida, Yuta Mashimo, Bernhard Misof , Oliver Niehuis, Ralph S. Peters, Malte Petersen, Lars Podsiadlowski, Kai Schütte, Shota Shimizu, Toshiki Uchifune, Jeanne Wilbrandt, Evgeny Yan, Xin Zhou, Sabrina Simon (2019): Evolutionary history of Polyneoptera and its implications for our understanding of early winged insects. PNAS Proceedings of the National Academy of Sciences USA 116 (8): 3024-3029. doi: /10.1073/pnas.1817794116
  12. ↑ a b Zorotype in the [Integrated Taxonomic Information System] (ITIS)
  13. ^ A b Michael S. Engel & David A. Grimaldi (2002): The First Mesozoic Zoraptera (Insecta). American Museum Novitates No. 3362: 1-20.
  14. ↑ Petr Kočárek, Ivona Horká, Robin Kundrata (2020): Molecular Phylogeny and Infraordinal Classification of Zoraptera (Insecta). Insects 11 (1), 51. doi: 10.3390 / insects11010051

literature

  • Bernhard Klausnitzer: Zoraptera, ground lice. In Westheide, Rieger (Hrsg.): Special zoology part 1: single-cell and invertebrate animals. Gustav Fischer Verlag, Stuttgart, Jena 1997; Pages 646-647.
  • Rolf G. Beutel, Frank Friedrich, Si-Qin Ge, Xing-Ke Yang: Insect Morphology and Phylogeny. Walter de Gruyter, Berlin and Boston 2014. ISBN 978-3-11-026263-6 , Chapter 6.13 Zoraptera. Pages 257-265.

Web links

  • Michael S. Engel: Zoraptera In: Tree of Life Web Project
  • Michael D. Hubbard: A Catalog of the Order Zoraptera (Insecta). Center for Systematic Entomology, Gainesville (Florida) 1990. ( PDF )