Scorpion Flat Spiders and Allies - Family: Trachycosmidae
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As of November 2023, the Trachycosmidae contains 148 species in 20 genera. They are medium-sized (some large) spiders, with many species having a severely flattened cephalothorax and abdomen enabling them to crawl underneath rocks or loose bark. Often dark-brown to black although some species display colours like golden brown to bright red particularly on the legs and cephalothorax. Azevedo et al. in 2022 elevated this group of spiders to family after it was erected in 2002 as a subfamily of the Trochanteriidae by the American arachnologist Prof. Emer. Norman Platnick. It contains also, a number of genera that formerly - again, as recently as 2022 - were included in the Trochanteriidae and the Gallieniellidae.
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As with the previous family, the Lamponidae, most of the Trachycosmidae are endemic to Australia and its' territories. Most common in Eastern Australia from Geraldton to Adelaide and in W.A. from Fitzgerald River west, then Northwards to Kalbarri; there is one species that also occurs on the island of Sulawesi (Indon.), one species each in New Guinea and on the Solomon Islands and, four species exclusive to New Caledonia. Of the remainder, 19 species from 10 genera may be encountered in the Northern Rivers. Note however, they are not common finds and telling them apart from their close relatives, the Trochanteriidae, may well prove to be problematic. Some of the distinguishing features do require detailed spider knowledge.
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Note that the currently accepted taxonomy of this group of spiders is by no means set in stone. Azevedo et al in 2022 posited that a number of the Australian genera formerly placed in Gallieniellidae (Meedo, Neato, Oreo, Peeto, and Questo) may actually deserve family status as a group themselves, since they seem morphologically distinct from other trachycosmids. Changes to the current taxonomic arrangement may well be forthcoming some time soon.
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Crossover Spider - Desognaphosa yabbra
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Meedo gympie
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Meedo munmorah (possible occurrence)
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Glass-gripping Flat Spider - Morebilus fumosus
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Major Flatrock Spider - Morebilus plagusius
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Neato beerwah
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Platorish flavitarsis
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Platorish jimna (possible occurrence)
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Pyrnus planus
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Rebilus binnaburra
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Rebilus brooklana
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Rebilus bulburin (possible occurrence)
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Rebilus lamongton
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Rebilus lugubris (possible occurrence)
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Rebilus monteith
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Tiny Trochanteriid - Tinytrema sandy (possible occurrence)
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Trachycosmus allyn
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Not-flat Trochanteriid - Trachycosmus sculptilis (possible occurrence)
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Trachytrema garnet
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Taxonomy:
Phylum: Arthropoda (Arthropods)
> Subphylum: Chelicerata (Chelicerates)
> Class: Arachnida (Arachnids)
> Order: Aranea (Spiders)
> Suborder: Araneomorphae (Typical Spiders)
> Infraorder: Entelegynea (Entelegyne Spiders)
> Superfamily: Gnaphosoidea (Ground Spiders and Allies)
> Family: Trachycosmidae (Scorpion Flat Spiders)
> Genus: Desognaphosa
> Species: D. yabbra - Crossover Spider
> Genus: Meedo
> Species: M. gympie
> Species: M. munmorah ^
> Genus: Morebilus
> Species: M. fumosus - Glass-gripping Flat Spider
> Species: M. plagusius - Major Flatrock Spider
> Genus: Neato
> Species: N. beerwah
> Genus: Platorish
> Species: P. flavitarsis
> Species: P. jimna ^
> Genus: Pyrnus
> Species: P. planus
> Genus: Rebilus
> Species: R. binnaburra
> Species: R. brooklana
> Species: R. bulburin ^
> Species: R. lamington
> Species: R. lugubris ^
> Species: R. monteith
> Genus: Tinytrema
> Species: T. sandy - Tiny Trochanteriid ^
> Genus: Trachycosmus
> Species: T. allyn
> Species: T. sculptilis - Not-flat Trochanteriid
> Genus: Trachytrema
> Species: T. garnet
* = likely
^ = possibly
References and links:
> Azevedo, G.H.F., Bougie, T., Carboni, M., Hedin, M. and Ramírez, M.J., (2022). 'Combining genomic, phenotypic and sanger sequencing data to elucidate the phylogeny of the two-clawed spiders (Dionycha).' Molecular Phylogenetics and Evolution 166(107327): 1-14. doi:10.1016/j.ympev.2021.107327
> Platnick, N.I., (2002). 'A revision of the Australasian ground spiders of the families Ammoxenidae, Cithaeronidae, Gallieniellidae, and Trochanteriidae (Araneae: Gnaphosoidea).' Bulletin of the American Museum of Natural History 271: 1-243. doi:10.1206/0003-0090(2002)271<0001:AROTAG>2.0.CO;2
> Platnick, N.I., (2008). 'A new subterranean ground spider genus from Western Australia (Araneae: Trochanteriidae).' Invertebrate Systematics 22(2): 295-299. doi:10.1071/IS07033
https://inaturalist.ala.org.au/taxa/1391319-Trachycosmidae
https://wsc.nmbe.ch/family/144/Trachycosmidae
> Azevedo, G.H.F., Bougie, T., Carboni, M., Hedin, M. and Ramírez, M.J., (2022). 'Combining genomic, phenotypic and sanger sequencing data to elucidate the phylogeny of the two-clawed spiders (Dionycha).' Molecular Phylogenetics and Evolution 166(107327): 1-14. doi:10.1016/j.ympev.2021.107327
> Platnick, N.I., (2002). 'A revision of the Australasian ground spiders of the families Ammoxenidae, Cithaeronidae, Gallieniellidae, and Trochanteriidae (Araneae: Gnaphosoidea).' Bulletin of the American Museum of Natural History 271: 1-243. doi:10.1206/0003-0090(2002)271<0001:AROTAG>2.0.CO;2
> Platnick, N.I., (2008). 'A new subterranean ground spider genus from Western Australia (Araneae: Trochanteriidae).' Invertebrate Systematics 22(2): 295-299. doi:10.1071/IS07033
https://inaturalist.ala.org.au/taxa/1391319-Trachycosmidae
https://wsc.nmbe.ch/family/144/Trachycosmidae
Photographic contributions: