Trichromothrips

Trichromothrips genus-group in Vietnam

Masumoto & Okajima (2005b) revised the Dorcadothrips genus-group of Mound & Palmer (1981) to include 13 genera as the Trichromothrips genus-group, and provided an identification key. These genera are mostly from the Oriental region, although Trichromothrips and Yoshinothrips are known from other areas. The species are all leafinhabiting rather than flower-living, and the following eight genera are associated with bamboo; Neocorynothrips, Okajimaella, Paithrips, Simulothrips, Takethrips, Trichromothrips, Watanabeothrips and Yoshinothrips. However, Trichromothrips species occur on many kinds of plants including Cyperaceae. Recorded here from Vietnam are10 species of eight of these genera.

These bamboo-inhabiting thrips probably breed on leaves or stems rather than in florets, because intervals between flowering of bamboos are generally very long. Moreover, except Takethrips, Trichromotrips and Yoshinothrips, these thrips usually have no (or vestigial) mesosternal spinula. According to Nonaka & Jangvitaya (1994b), Takethrips magas that is newly recorded below has a long mesothoracic spinula, but this is variable, absent, short to weak, or long within specimens studied here. The absence of a mesosternal spinula may indicate that these thrips live under the leaf sheath. Thrips with a weak ovipositor having no serration, a very unusual character state among Thripidae, usually inhabit grass florets rather than leaves. For example, Plesiothrips is usually found in florets of Lolium [Poaceae] in Japan. In contrast, T. megas, which also has a weak ovipositor, probably lives on leaves or on stems under the leaf sheath.

In Japan, Yoshinothrips apparently breeds on older leaves rather than on young ones, because it is usually collected from older bamboo leaves. Trichromothrips is also found on older hard leaves of evergreen trees such Cinnamomum, Machilus [Lauraceae] and Aucuba [Corbaceae] or ferns rather on than fleshly soft leaves, thus members of this genus also apparently breed on older tissues.