Sericothripinae

Lima, Élison Fabrício B. & Mound, Laurence A., 2016, Species-richness in Neotropical Sericothripinae (Thysanoptera: Thripidae), Zootaxa 4162 (1), pp. 1-45 : 3-4

Sericothripinae Karny

This subfamily was erected by Karny (1921), and is generally considered a monophyletic group ( Buckman et al. 2013). However, the classification into three genera probably does not reflect phylogenetic relationships ( Lima & Mound 2016), and a total of 15 generic names are available for the 152 listed species (ThripsWiki 2016). These species share the following character states:

Head transverse with 3 pairs of ocellar setae; antennae usually 8-segmented, segments III & IV each with a forked sense cone, VI with an elongate narrow base to one external sense cone; occipital apodeme present; maxillary palps 3-segmented; fore femora and fore tibiae with numerous transverse rows of microtrichia; pronotum usually with a distinguishable darker blotch; mesosternum with spinula; first vein of fore wing with setal row continuous, second vein with no setae or with one or two near wing apex; posterior fringe cilia wavy (except Neohydatothrips masrensis ); lateral thirds of abdominal tergites II–VII with dense rows of fine microtrichia; posteromarginal comb complete on tergite VIII; tergite IX with at least four pairs of robust posteromarginal setae, also at least two pairs of mid-dorsal setae. Males usually with a pore plate on one or more sternites; tergite IX without drepanae.

Metasternal plate. During the preparation both of this paper, and also of a recent publication on sericothripine systematics ( Lima & Mound 2016), the authors recognized that the customary interpretation of the metasternum of these thrips was not entirely valid. For some years, the interpretation has been that the “anterior margin of the metasternum” is either weakly or strongly emarginate ( Mound & Tree 2009), this difference being used in the generic classification. However, light microscopy indicates that in species of both Hydatothrips and Neohydatothrips there are setae on the metasternum anterior to the distinctive darkly sclerotised area ( Figs 10, 13 ). Thus, the anterior margin of this area cannot represent the anterior margin of the metasternum. Based on these observations, the term “metasternal plate” was adopted in this paper, in the full realisation that its morphological significance remains unclear. Subsequent to these two papers being prepared, Gerald Moritz (Martin-Luther Universität Halle-Wittenberg, Germany) kindly prepared an SEM image ( Fig. 2 ) of the metasternum of the Australian species, Hydatothrips argenticinctus . The metasternal plate of this species is distinctive when examined with transmitted light ( Fig. 1 ), or even, due its pigmentation, when examined in ethanol by reflected light. But the SEM image indicates that this sclerite is not on the surface, but is an internal structure. Presumably it is a thickening of the inner surface of the metasternum, and possibly represents a muscle insertion area.

Figures

FIGURES 9 – 14. Hydatothrips species. canavaliae 9 – 11: (9) meso and metanota; (10) metasternal plate; (11) larva II abdomen. (12) gliricidiae meso and metanotum. (13) volcano metasternal plate. (14) sternalis sternites V – VI.

FIGURES 1 – 2. Metasternum of the Australian species Hydatothrips argenticinctus. (1) transmitted light view; (2) SEM image (courtesy Gerald Moritz, Halle).