Psalidothrips

 Head of Psalidothrips longistylus, from Okajima (1983).

Belongs within: Phlaeothripidae.

Psalidothrips is a genus of thrips found in leaf litter with a distinctively rather broad, dorsoventrally flattened head (Mound & Marullo 1996).

On Psalidothrips
Published 13 March 2022

Many of you may know thrips as small insects that infest buds and young shoots of garden plants, stymieing growth and causing malformed development. However, there is also a wide diversity of thrips species that feed on fungi, inhabiting leaf litter and other fallen vegetation. In tropical and subtropical regions of the world, one of the more numerous genera of such fungus-feeders is Psalidothrips.

Winged female (left) and wingless male of Psalidothrips comosus, from Zhao et al. (2018).

Close to fifty species of Psalidothrips have been described from various locations around the world (Wang et al. 2019). They are most commonly found among leaf litter and are believed to feed on fungal hyphae. Most Psalidothrips are relatively small, pale thrips, yellowish or light brown in coloration. As members of the family Phlaeothripidae, the last segment of the abdomen is modified into a tube ending in a ring of setae; in Psalidothrips, this tube is commonly short and the terminal setae are often longer than the tube.

As is common among thrips, the recognition of Psalidothrips and its constituent species is often complicated by within-species variation. Many species are known as both winged and wingless forms (Wang et al., 2019, note that Australian species seem particularly prone to winglessness). Wingless forms often show reductions in the sclerotisation of the thorax. It is difficult to name a single feature of the genus that does not find exception in some species or other. Most species are weakly sculpted. For the most part, the maxillary stylets are short and sit low and far apart in the head when retracted. The mouth-cone is similarly short and rounded. The head is often fairly short with rounded cheeks that do not bear strong setae. Setae on the anterior margin of the pronotum are often reduced. The wings, if present, are often more or less constricted at about mid-length. Many phlaeothripids possess a series of large setae on the abdomen that hold the wings in place when folded back; in individuals of Psalidothrips with such setae (obviously, they tend to disappear in wingless individuals), they are often relatively few in number and simply curved.

Many of these features are related to the thrips’ litter-dwelling habits. The short mouthparts, for instance, presumably reflect how these thrips are gleaning fungi from the surface of leaves without needing to pierce the leaf’s cuticle. As such, it will be interesting to see how the genus holds out as our understanding of thrips phylogeny improves. Is this a true evolutionarily coherent assemblage, or disparate travellers who are following a fashion?

Systematics of Psalidothrips

Characters (from Mound & Marullo 1996): Head as wide as long, dorsoventrally flattened, often incut behind large eyes; maxillary stylets unusually low in head and wide apart; maxillary palps unusually small; antennae 8-segmented, segment III with two or three sense cones, segment IV with three or four; pronotal anteromarginal and anteroangular setae small; fore tarsal tooth absent; forewing without duplicated cilia, sub-basal wing setae minute sternite VIII of male with glandular area.

Psalidothrips Priesner 1932 [incl. Hennigithrips Johansen 1986]MM96
|--*P. amens Priesner 1932MM96
|--P. ananthakrishnani (Johansen 1986) [=*Hennigithrips ananthakrishnani]MM96
|--P. angustus Zhao, Zhang & Tong 2018ZZT18
|--P. armatus Okajima 1983ZZT18
|--P. ascitus (Ananthakrishnan 1969) [=Callothrips ascitus]ZZT18
|--P. bicoloratus Wang, Tong & Zhang 2007ZZT18
|--P. bipictus Wang, Mound & Tree 2019WMT19
|--P. brittoni Wang, Moung & Tree 2019WMT19
|--P. cecryphalus Wang, Mound & Tree 2019WMT19
|--P. chebalingicus Zhang & Tong 1997ZZT18
|--P. comosus Zhao, Zhang & Tong 2018ZZT18
|--P. conciliatus Hood 1955 [incl. P. lepidus Zur Strassen 1972]MM96
|--P. consimilis Okajima 1992ZZT18
|--P. daedalus (Karny 1912) [=Cryptothrips daedalus]MP83
|--P. daguilari Wang, Mound & Tree 2019WMT19
|--P. dissidens Hood 1955MM96
|--P. driesseni Wang, Mound & Tree 2019WMT19
|--P. elagatus Wang, Tong & Zhang 2007ZZT18
|--P. fabarius Zhao, Zhang & Tong 2018ZZT18
|--P. gloriousi Wang, Mound & Tree 2019WMT19
|--P. greensladeae Wang, Mound & Tree 2019WMT19
|--P. howei Wang, Mound & Tree 2019WMT19
|--P. latizonus Zhao, Zhang & Tong 2018ZZT18
|--P. lewisi (Bagnall 1914) [=Trichothrips lewisi; incl. P. alaris Haga 1973]ZZT18
|--P. longicepsZZT18
|--P. longidens Wang, Tong & Zhang 2007ZZT18
|--P. longistylus Okajima 1983MM96
|--P. minantennus Wang, Mound & Tree 2019WMT19
|--P. nigroterminatus Zhao, Zhang & Tong 2018ZZT18
|--P. ochraceusZZT18
|--P. pitkini Okajima 1983MM96
|--P. platetus Wang, Mound & Tree 2019WMT19
|--P. postlei Wang, Mound & Tree 2019WMT19
|--P. retifer Hood 1955MM96
|--P. simplus Haga 1973ZZT18
|--P. sturmi Zur Strassen 1972MM96
|--P. tayloriMDT13
|--P. tritus Wang, Mound & Tree 2019WMT19
|--P. trivius Wang, Mound & Tree 2019WMT19
|--P. umbraticus Hood 1955MM96
|--P. verus Wang, Mound & Tree 2019WMT19
`--P. wellsae Wang, Mound & Tree 2019WMT19

*Type species of generic name indicated

References

[MDT13] Mound, L. A., L.-H. Dang & D. J. Tree. 2013. Genera of fungivorous Phlaeothripinae (Thysanoptera) from dead branches and leaf-litter in Australia. Zootaxa 3681 (3): 201–224.

[MM96] Mound, L. A., & R. Marullo. 1996. The thrips of Central and South America: an introduction (Insecta: Thysanoptera). Memoirs on Entomology, International 6: 1–487.

[MP83] Mound, L. A., & J. M. Palmer. 1983. The generic and tribal classification of spore-feeding Thysanoptera (Phlaeothripidae: Idolothripinae). Bulletin of the British Museum (Natural History): Entomology series 46 (1): 1–174.

Okajima, S. 1983. Studies on some Psalidothrips species with key to the world species (Thysanoptera: Phlaeothripidae). Journal of Natural History 17 (1): 1–13.

[WMT19] Wang, J., L. A. Mound & D. J. Tree. 2019. Leaf-litter thrips of the genus Psalidothrips (Thysanoptera, Phlaeothripidae) from Australia, with fifteen new species. Zootaxa 4686 (1): 53–73.

[ZZT18] Zhao, C., H. Zhang & X. Tong. 2018. Species of the fungivorous genus Psalidothrips Priesner from China, with five new species (Thysanoptera, Phlaeothripidae). ZooKeys 746: 25–50.

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