Species complexes and the generic classification of leaf-litter thrips of the tribe Urothripini (Phlaeothripidae)

Abstract

Collections of the predominantly wingless urothripine Thysanoptera from leaf litter in Australia show little variation in external morphology within any one population, although the variation between populations is frequently very considerable. Morphological segregates in which winged individuals are known show little variation between populations, and these segregates can be regarded as distinct species. However, morphological segregates in which winged individuals are not known exist in the field as a complex of similar but distinctive local forms. Taxonomy is concerned with the interpretation in biological terms of morphological difference, but the significance of these distinctive populations cannot be determined at present, whether they are species, subspecies, or local variants. However, this high rate of incipient speciation of the Urothripini is evidently related, at least in part, to the low degree of dispersive activity of the wingless forms. The resulting complicated pattern of variation at the species level is reflected in the unsatisfactory generic classification, and several of the characters which have been used for distinguishing genera are here shown to be of little value. As a result four genera, Bournieria, Ramachandraiella, Transithrips, and Verrucothrips, are here placed in synonymy with Baenothrips, and a key is provided to the remaining 13 genera of Urothripini from the world. An account is given of the eight species in five genera known from Australia, including two new species: Baenothrips caenosus (Stannard), comb. nov. ; Baenothrips moundi (Stannard), comb. nov. ; Biconothrips reedi Stannard; Habrothrips curiosus Ananthakrishnan; Octurothrips pulcher Priesner; Stephanothrips occidentalis Hood & Williams; S. barretti, sp, nov.; S. ferrari, sp. nov. In addition, knechteli Priesner is transferred to Amphibolothrips, comb. nov., and erythrinus Pelikan is transferred to Baenothrips, comb. nov.

Thysanoptera (Insecta) of Barrow Island, Western Australia

“…The remaining Phlaeothripinae in the Barrow Island samples were all considered to be fungus feeding. Adurothrips and Biconothrips species live in leaf-litter (Mound 1995;1972b), whereas species of Jacotia are commonly found living at the base of tussocks of grasses or Lomandra (Mound 1995). In contrast, species of Holothrips, Majerthrips and Senithrips presumably all live on dead twigs and branches, although there have been no studies on their biology (Mound and Minaei, 2006).…”

New generic synonyms in the Palaeotropical genus Urothrips (Thysanoptera: Phlaeothripinae) with one new species from Seychelles

“…Within the key to genera of urothripines presented by Mound (1972), there is one group of four genera that is distinguished by the following three character states: absence of elongate setae on anterior margin of head; presence of prominent external fore tarsal hamus; reduction of prosternal basantra (=praepectus) to a pair of small triangles placed laterally. These four genera were each erected for a single species, and were distinguished from each other as follows:…”

“…Such highly visible differences in structure are reflected in the number of generic names proposed for species in this group. These patterns of variation amongst urothripines were discussed by Mound (1972), and one conclusion was that Baenothrips Crawford is a pantropical genus with four generic synonyms.…”

“…A further conclusion in Mound (1972) involving the classification of urothripines concerned dispersive behavior. Species in this group that live in leaf-litter or on dead twigs, and whose behavior involves crawling up above soil level, are likely to be wind dispersed.…”

A new species of Baenothrips Crawford from China (Thysanoptera, Phlaeothripidae)

“…These thrips are considered to be fungusfeeding, with most living in leaf litter, grass tussocks or dead twigs (Stannard 1970;Mound 1972;Okajima 1994). However, some species, such as B. moundi Stannard of Australia, can crawl up above soil level to grass stems, and are likely to be winddispersed (Mound 1972;Ulitzka and Mound 2014). The new species described below has similar dispersive behaviour, and can be collected not only in leaf litter but also on fresh leaves or stems of grass, fern, and dicotyledons.…”