Generic diagnosis

Small, dark apterous or micropterous Phlaeothripidae with few sculpture lines and short maxillary stylets. Head usually wider than long; postocular setae long and capitate; maxillary stylets scarcely retracted anterior to postoccipital ridge. Antennae usually 8-segmented, but some species 7-segmented; antennal segment III with 0 or 1 sense cone (rarely 2 or 3), IV usually with 2 sense cones. Pronotum usually with 5 pairs of major capitate setae, but anterior 2 pairs often small; notopleural sutures incomplete. Prosternal basantra weak or absent; ferna well-developed; mesopresternum complete; metathoracic sternopleural sutures absent. Fore tarsal tooth absent in both sexes, but inner apex of tarsus sometimes with recurved claw-like structure. Pelta D-shaped often rather weak; tergite IX setae S1 longer than tube. Male sternite VIII without pore plate.

Nomenclatural data

Williamsiella Hood, 1925: 60. Type species Williamsiella bicoloripes Hood, 1925, by monotypy.

There are 26 species listed in this genus (ThripsWiki, 2022).

Australian species
Williamsiella insperata Mound & Tree, 2015: 371

Relationship data

Presumably related to the Hoplothrips group within the Phlaeothrips-lineage, but the members of Williamsiella have unusually short maxillary stylets. There is considerable structural variation between species, with antennal segment VIII in a few species long and slender, in a few others fused to VII, and further species exhibiting a range of form between these extremes.

Distribution data

The genus is widespread around the warmer parts of the world, mainly in the Neotropics, but with one species from northern Australia (near Darwin and also at Cape Tribulation in Queensland).

Biological data

The species of this genus are associated with lichens and mosses growing on dead branches.

References

Mound LA (1989) Systematics of thrips (Insecta: Thysanoptera) associated with mosses. Zoological Journal of the Linnean Society 96: 1–17.

Mound LA & Tree DJ (2014) Species of Lissothrips and Williamsiella from mosses and lichens in Australia and New Zealand (Thysanoptera, Phlaeothripinae). Zootaxa 3946 (3): 361–373.

ThripsWiki (2022) ThripsWiki - providing information on the World's thrips. Available from: http://thrips.info/wiki/ (Accessed 15.iii.2022)