Haplogynae
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Spider ( Scytodes thoracica ) |
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| Simon , 1893 |
The Haplogynae (from Greek ἁπλός ( haplós ) "simple" and γυνή ( gynḗ ) "woman, female") are a sub-order of the real spiders with relatively simply built sexual organs. This small group differs essentially from the entelegynae with their complexly constructed genital organs and is more similar to the anatomically simpler tarantulas and the limb spiders .
The structure of the genital organs is so species-specific that they represent the safest species identification feature for arachnologists . The downside is that the spider won't survive the determination.
Other features (eyes, spinning glands, etc.) are not well suited for differentiation. Most species of the haplogynous spiders, unlike most entelegynes, have only six eyes. Some species of the family Caponiidae (Caponioidea) and species of the genus Tetrablemma ( Tetrablemmidae ) only have four eyes. Only members of the Plectreuridae have 8 eyes. In terms of weaving technology, both cribellate spiders and ecribellate spiders are in this group: Filistatidae are the only cribellates, the rest of the group is ecribellate, although the free-hunted food spiders and the quivering spiders with their curling threads, also from an evolutionary point of view, have a special position.
Construction of the haplogynous genital organs
The females of the true haplogyne spiders, like the tarantula-like and more primitive spiders, do not have a sclerotized plate with insertion openings ( epigyne ) above the genital opening . The genital opening goes more or less directly into the seminal receptacles ( Receptaculum seminis ), which in turn open directly into the outer part of the two-part uterus , the uterus externus. Fertilization takes place in the external uterus. The duct for introducing the globe is thus also the fertilization duct .
The simple structure of the female sexual organs has its counterpart in the simple structure of the male copulatory organs, the bulbs. They are protuberances on the tarsus wall of the pedipalps and house a spiral-shaped seed tube ( spermophore ), which sucks up the deposited sperm drop like a pipette and stores it until copulation.
Copulation and fertilization
In the haplogynae, the globe is completely inserted into the external seminal duct of the genital opening up to the receptacle. The semen is then presumably displaced by a glandular secretion and released into the receptacle. Haplogyne males usually insert both bulbs at the same time. While a multitude of different copulation positions has been demonstrated in the Entelegynae, the males of the Haplogynae usually approach the female from the front. The copulation resembles that of the tarantulas and articulated spiders . The female aligns his front body ( prosoma ) with the male and the male inserts both bulbs. After mating, both carefully separate from each other.
The structure is also important for evolution, because the females of Indicoblemma lannaianum seem to be able to fully control the fertilization process. It is possible that females of other species can also store sperm from different males and "choose" their fertilization partner after multiple copulations. In the case of the entelegynous fat spider ( S. bipunctata ) it was also observed that two matings take place with an interval of more than 6 weeks before the female drives out the eggs.
The bulbs only fit into the genital opening of a female of the same species. The key-lock principle could be interpreted as an important mechanism for preventing the crossing of two species. However, it is more likely that hybridization is prevented at the behavioral level. It often happens that males barn at alien females. However, if they do not react to the partner in a species-specific manner, the male is ignored or attacked.
Systematics
The cladogram according to Norman I. Platnick et al. and gives the superfamilies after Hallan. In the following illustration, the Trogloraptoridae family, which was only described in 2012, is missing , which belongs to the superfamily Dysderoidea and occupies a basal position there. In addition, Wheeler et al. 2017 the family Pacullidae reopened. Number of genera and species according to the World Spider Catalog . (As of June 2016)
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Web links
- Natural History Museum of the Burgergemeinde Bern: World Spider Catalog Version 17.0 - Home
- Heimer & Nentwig (1991). Spinning Central Europe - online key
- G. Hormiga, G. Giribet: Systematics and Monography of Araneoid Spiders
Individual evidence
- ↑ a b c d e Rainer F. Foelix: Biology of the spiders. Georg Thieme Verlag Stuttgart 1979, ISBN 978-3-13-575801-5
- ^ Coddington, JA & Levi, HW (1991). Systematics and Evolution of Spiders (Araneae). Annu. Rev. Ecol. Syst. 22: 565-592.
- ↑ Cf. Gertsch, Willis J. 1979: American Spiders, 2nd edition. Van Nostrand Reinhold, New York. P. 149. ISBN 0-442-22649-7
- ↑ M. Burger et al. (2005): Complex genital system of a haplogyne spider (Arachnida, Araneae, Tetrablemmidae) indicates internal fertilization and full female control over transferred sperm. Journal of Morphology 267 (2): 166-186. doi: 10.1002 / jmor.10394
- ↑ P. Rohde, oral communication 2008
- ↑ Crane, J .: Comparative biology of salticid spiders at Rancho Grande, Venezuela. An Analysis of Display. Zoologica, 34 (1949) 159. Quoted in Foelix: 1979.
- ↑ Grasshoff, M .: Construction and functional analysis of copulatory organs of some orb web spiders. Onto. u. Red. Senckenberg Naturforschende Gesellschaft, 24 (1973) 129. Quoted in Foelix: 1979.
- ^ Platnick, NI, JA Coddington, RR Forster and CE Griswold. 1991. Spinneret morphology and the phylogeny of haplogyne spiders (Araneae, Araneomorphae). American Museum Novitates, 3016: 1-73.
- ^ Hallan, Joel 2006: SYNOPSIS OF THE DESCRIBED ARANEAE OF THE WORLD. Texas A&M University Department of Entomology. ( Memento of the original from December 11, 2014 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.
- ↑ Griswold et al. 2012, pp. 81-82.
- ↑ Wheeler et al. (2017): The spider tree of life: phylogeny of Araneae based on target-gene analyzes from an extensive taxon sampling. Cladistics 33 (6), pp. 576-616. doi: 10.1111 / cla.12182
- ↑ Natural History Museum of the Burgergemeinde Bern: World Spider Catalog Version 17.0 - home page .
