Mesothrips Zimmermann, 1900

Mound, Laurence A. & Minaei, Kambiz, 2007, Australian thrips of the Haplothrips lineage (Insecta: Thysanoptera), Journal of Natural History 41 (45 - 48), pp. 2919-2978 : 2965-2966

Mesothrips Zimmermann

Mesothrips Zimmermann 1900, p 12 . Type species: Mesothrips jordani Zimmermann.

A total of 44 species is described in this genus, all from South-East Asia, particularly Indonesia, India, and Vietnam, but with two from Australia and one from Guam. In the absence of revisionary studies the significance of many of these species must remain in doubt, because one species discussed below is now recognised as highly variable. Moreover, although they are all ‘‘gall thrips’’ there appears to be little evidence that any of them induce galls. These thrips are commonly found in association with other thrips species, and they are probably phytophagous kleptoparasites rather than gall inducers. This suggestion is supported by the fact that both sexes vary greatly in body size, as in the related genus Euoplothrips . Although apparently differing in biology, Mesothrips species are closely related to those of Dolichothrips , as discussed above. Two species have been described from Australia, but these are here considered synonymous with the type species of the genus.

Recognition

Dark brown species exhibiting size-correlated polymorphism in fore tarsal tooth development; antennae eight-segmented, III with three sensoria, IV with four sensoria; head sharply constricted to basal neck ( Figure 8 ) with a few small stout setae on cheeks, maxillary stylets retracted about half-way to postocular setae; prosternal basantra small, mesopresternum divided; fore tarsal tooth large in large individuals of both sexes; fore wing constricted medially; tergites II–V with additional sigmoid setae lateral to the major wingretaining setae.

Mesothrips jordani Zimmermann

Mesothrips jordani Zimmermann 1900, p 16 .

Mesothrips australiae Hood 1918, p 139 . syn. n.

Mesothrips bianchii Ananthakrishnan 1976, p 191 . syn. n.

The character states given for M. bianchii by Ananthakrishnan do not distinguish this from the species described by Hood, and neither of these can be distinguished satisfactorily from the widespread Oriental species M. jordani Zimmermann. In describing the species, Hood (1918) stated that M. australiae was perhaps merely a race of M. jordani , and in view of the wide range of variation within samples from any single locality there is no good evidence that more than one species is represented by these three names. Moreover, considering the variation that has been observed in samples both from Australia and from Kuala Lumpur, some of the other nominal species recognised in this genus by Ananthakrishnan (1976) are likely to be synonymous.

Prof. Shuji Okajima of Tokyo kindly provided the following information concerning variation in length (in Mm) of the pronotal posteroangular setae amongst samples of M. jordani that he has collected in South-East Asia: Bali (17 females) 40–85; Singapore (two females) 65–80; Taiwan (about 50 females) 80–130; India (one female) 60; Japan Ryukyus (one large female) 130–140. The species is known from India, West Malaysia, Indonesia, Taiwan, China, and southern Japan (Ryukyu Islands) ( Okajima 2006). In Australia, it has been taken widely in the coastal rainforests of Queensland, including the Botanic Gardens at Mt Cootha, Brisbane, at Noosa Head, Gordonvale, and Atherton. Although living in leaf-roll galls of Ficus species , the wide range of structural variation in both sexes suggests that this thrips is a phytophagous kleptoparasite in the galls of Gynaikothrips species , rather than a gall-inducer.

Podothrips Hood

Podothrips Hood 1913, p 67 . Type species: Podothrips semiflavus Hood.

The members of this worldwide genus all appear to be coccid predators living on Poaceae . An account of 18 species in this genus was given by Ritchie (1974), including a list of four generic synonyms, although subsequently four further species have been described from South-East Asia and two from New Zealand. The Australian fauna of this genus now comprises 10 species plus the Asian species, P. lucasseni . Nine of the 10 species constitute a single lineage, the P. australis group, in that they share the following character states: fore tibial inner margin with sub-apical setal-bearing tubercle but no apical tooth; antennal segments III and IV each with two sensoria; fore wing with no duplicated cilia; tergite VII with wing-retaining setae small and straight. The 10th species is divergent, in that it is apterous, and antennal segment III lacks sensoria and has a pronounced sub-basal ring, but the fore tibial sub-apical tubercle is similar to the other members of the P. australis group. As is typical of Podothrips , in all of the Australian species the prosternal basantra are longer than wide, and the pronotal anteromarginal setae are minute. The range of body colour within the genus is remarkable, from largely clear yellow to uniformly brown, but with most Australian species strikingly bicoloured. As in Karnyothrips melaleucus , the anal setae of most species are particularly long.

Figures

Figures 1–15. (1) Bagnalliella nigricoxae, holotype. (2) Dyothrips pallescens, pronotum. (3) Dolichothrips reuteri, mouth cone. (4) Androthrips monsterae, fore femora. (5) Priesneria peronis, antenna. (6) Karnyothrips melaleucus, head, pronotum, and fore legs. (7) Euoplothrips bagnalli, fore legs of small and large males. (8) Mesothrips jordani, head. (9) Haplothrips acaciae, head and pronotum. (10) H. anceps, head, pronotum, and right fore leg. (11) H. acaciae, pelta. (12) H. anceps pelta. (13) H. angusi pelta. (14) H. avius, head. (15) H. angusi, prosternites.