Mycterothrips Trybom, 1910

Masumoto, Masami & Okajima, Shûji, 2024, Further study of the genus Mycterothrips Trybom (Thysanoptera: Thripidae) in Japan, with description of a new species and a new record, Zootaxa 5489 (1), pp. 107-124 : 109

Genus Mycterothrips Trybom

Mycterothrips species often display distinct sexual dimorphism in the length of antennal segments. In some species such as M. araliae (Takahashi) from Taiwan and M. fasciatus Masumoto & Okajima from Japan, male antennal segments are the same shape as that of females, but in some species such as M. nilgiriensis (Ananthakrishnan) from the Oriental region and M. egonoki Masumoto & Okajima from Japan, male antennal segment VI is much longer than that of female and has numerous setae. Other species indicate some degrees of intermediate length between these types. Masumoto & Okajima (2006) recognized six species-groups in this genus based on character states of male antennal segment VI and shape of apex of hypomere. They also discussed the relationship between Mycterothrips and Trichromothrips genus-group. Mycterothrips shares some character states with many members of this group, especially: antennal segment I with paired dorso-apical setae, fore wing first vein with long gap in setal row and two distal setae, and mesosternum without complete sternopleural suture. In addition, in Mycterothrips males have abdominal tergite IX with paired minute setae or tubercles near posterior margin, which appear to be homologous with paired horn-like projections called “drepanae” in Trichromothrips Priesner and related genera. However, Mycterothrips can be distinguished from the latter group by having abdominal tergite VIII with complete posteromarginal comb, metasternum with spinula and male abdominal sternites without pore plates. Moreover, Mycterothrips is possibly closely related to Craspedothrips Bhatti , Plesiothrips Hood and Sorghothrips Priesner , which also have antennal segment I with paired dorso-apical setae and much elongate male antennal segment VI with numerous setae. In contrast, Zhang et al. (2019) indicated that Mycterothrips was sister group of Megalurothrips genus-group, and this clade was placed far from Trichromothrips genus-group by phylogenetic analysis based on morphological character states. Moreover, Craspedothrips was included in the Megalurothrips genus-group, but Plesiothrips and Sorghothrips were not included in any group in their analysis. Some species of Megalurothrips Bagnall have the male abdominal tergite IX with a pair of small thorn-like setae or tubercles near posterior margin, and these appear to be homologous with the small setae on males of Mycterothrips .

Diagnosis. Usually three pairs of ocellar setae, but pair I often represented by a single seta or rarely absent; usually five pairs of postocular setae, S2 and S3 usually closer to each other than to S1 and S4 respectively.Antennae usually 8-segmented, sometimes 7-segmented, rarely 6-segmented in male; segment I with paired dorso-apical setae, III and IV each with forked sense-cones. Pronotum with two pairs of posteroangular setae, two pairs of posteromarginal setae. Metascutum irregularly reticulate medially, with median pair of setae at or near anterior margin, no CPS. Fore wing first vein with long gap in setal row, 5–9 (usually 7) basal and 2 distal setae, second vein with equally spaced many setae; clavus 5 (rarely 4 or 6) veinal and 1 discal setae. Mesosternopleural sutures present but incomplete. Spinula present on both meso- and metasterna. Tarsi 2-segmented. Abdominal tergites without ctenidia, II–VIII often with numerous ciliate microtrichia arising from sculpture lines lateral to S2 setae, VIII with posteromarginal comb complete; tergite X with median split distally or no split; sternites with or without discal setae; pleurotergites without discal setae. Male without pore plate on abdominal sternites.