Two new Australian fungus-feeding thrips in two new Plectrothripini genera (Thysanoptera, Phlaeothripinae) 

Abstract

Two new genera are erected of plectrothripine Phlaeothripidae from northern Australia, each based on a single species. One has a long stout projection ventrally on the second antennal segment, the other has a unique arrangement of the dorsal facets of the compound eyes. In both of them the thoracic ventral sclerites are extensively eroded. The tribe Plectrothripini is one of the few apparently discrete lineages within the large and complex subfamily Phlaeothripinae (Dang et al. 2014). The species in this Tribe are all fungus-feeders on dead branches, and the group is found in the tropics worldwide. Okajima (1981) provided an extensive, illustrated account of the Plectrothripini, recognising 10 genera and almost 50 species, to which Tyagi et al. (2016) added one further species. Six of these genera remain monotypic, with two genera each comprising five or six species, and Plectrothrips itself with about 30 species. This asymmetry of taxon distribution, with a high proportion of monotypic genera, is due to the presence of certain characters in unusual autapomorphic states. Phylogenetic relationships within the tribe are further confused here through the diagnosis of two new monotypic genera for species from the tropical north of Australia. One of these new species has a bizarre projection ventrally on the second antennal segment (Fig. 5), whilst the other has the structure of the compound eyes unique amongst Phlaeothripidae (Figs 7, 8).Membership of the Tribe Plectrothripini is fairly clear, with the species sharing most of the following character states as indicated by Okajima (1981): antennae 8-segmented, segment II with the campaniform sensillum on the basal half, III-IV with a variable number of short, stout sense cones, VIII elongate with narrow base. Head with posterior ocelli close to compound eyes. Pronotum commonly with sclerotised plate eroded and reduced; prosternal basantra absent; fore tarsal tooth large; apex of hind tibiae commonly with stout setae. Pelta wide at base, tergite II eroded laterally; sternites often with reticulate glandular areas.Kremnothrips gen.n.Diagnosis. Head twice as long as width across eyes, prolonged in front of eyes over bases of antennae; compound eyes with few and weakly defined facets; cheeks slightly constricted behind eyes, vertex lacking sculpture except weakly reticulate along posterior margin; postocular setae long and finely pointed, maxillary stylets retracted to postocular setae, close together medially, mandible long and robust (Fig. 1). Antennae 8-segmented (Figs 4, 5); segment I the longest; II dorsally with 2 pairs of setae and campaniform sensillum in basal half, ventrally with long apical spur (Fig. 5); III asymmetric with outer margin swollen and base slender, with 3 short stout sense cones, segment IV with 4; V-VI each with 2; IV-VIII bulbous with pedicels narrow. Pronotum with 5 pairs of slender pointed major setae but anteromarginal setae variable in length; notopleural sutures incomplete (Fig. 2); basantra absent but 2 or 3 setae present; ferna narrowin...

Autapomorphies in the generic classification of Plectrothripini (Thysanoptera, Phlaeothripinae), with a new genus and a new record from Malaysia

“…The Plectrothripini is one of the few reasonably distinct sub-groups among the 3000 species comprising the Thysanoptera subfamily Phlaeothripinae (Dang et al 2014;Mound & Tree 2017). Including the new species described below, this Tribe now numbers 60 species, but 32 of these are placed in the genus Plectrothrips, ten in Streptothrips and six in Chirothripoides, with both Menothrips and Mastigothrips each having two species, and the remaining eight species each placed in separate monobasic genera.…”