Trichromothrips

Masumoto, Masami & Okajima, Shûji, 2005, Taiwan, with descriptions of four new species and a review of the Trichromothrips group of genera, Zootaxa 1082, pp. 1-27 : 2-3

Trichromothrips genus­group

Bhatti (1969, 1978b and 2000) indicated that the presence of dorsal apical setae on antennal segment I is an important characteristic to distinguish some genera, and is often useful in interpreting taxonomic position in the Terebrantia (also see Mound & Marullo, 1996: 176). These setae on antennal segment I are absent in members of the families Merothripidae , Melanthripidae and Aeolothripidae that retain many plesiotypic character states, and are also absent in many genera of Thripidae . Therefore, the presence of these setae appears to be an apomorphic condition in certain Thripidae genera.

The weakly defined Dorcadothrips genus­group of Mound & Palmer (1981) included Dorcadothrips (= Trichromothrips ) and Trichromothrips together with the genus of predatory species, Scolothrips . Although these genera are similar to each other in general appearance, Scolothrips species lack dorsal apical setae on antennal segment I, and this genus is probably unrelated to Trichromothrips . In contrast, the following genera share with Trichromothrips a series of character states as indicated below: Cricothrips Trybom , Laplothrips Bhatti , Neocorynothrips Ramakrishna & Margabandu , Octothrips Moulton , Okajimaella Nonaka & Jangvitaya , Paithrips Nonaka & Jangvitaya , Pteridothrips Priesner, Simulothirps Nonaka & Jangvitaya , Takethrips Nonaka & Jangvitaya , Trachynotothrips Masumoto & Okajima , Watanabeothrips Okajima , and Yoshinothrips Kudo (also see Bhatti, 2000; Mound & Masumoto, 2004). These genera, comprising the monophyletic Trichromothrips genus­group, share the following character states: antennal segment I with dorsal apical setae; compound eyes more or less bulged and head more or less (often distinctly) constricted behind compound eyes; mesothoracic sternopleural suture absent (present incompletely in Cricothrips ); abdominal terga II to VII with three setae (B3–B5 setae) along lateral margin arranged in straight line (B3 or B4 setae often situated mesad of setal row in Cricothrips , Neocorynothrips ); posteromarginal comb of abdominal tergum VIII absent (some small microtrichia present in Trachynotothrips ); male often with a pair of horn­like processes (=drepanae) on posterior margin of abdominal tergum IX and with small scattered glandular areas on abdominal sterna (drepanae absent in Pteridothrips , drepanae often reduced in Trichromothrips , male unknown in Takethrips ). Trachynotothrips has an elongate metasternal furca similar to that found in Dendrothripinae , but this may represent convergence associated with jumping activity ( Masumoto & Okajima, 2005). Nonaka & Jangvitaya (1993) stated that Yoshinothrips was closely related to their genus Clypeothrips described from bamboo in Thailand as having elongate ocellar setae III, 3­segmented maxillary palpi, 2­segmented tarsi and scattered glandular areas of male. However, Clypeothrips appears to be unrelated to Yoshinothrips and the genera of the Trichromothrips genus group because combination of the former three character states is often found in many unrelated genera and Clypeothrips lacks dorsal apical setae of antennal segment I.

Okajimaella , Paithrips , Simulothrips and Watanabeothrips share an unusual character state in the position of ocellar setae III. These setae arise at the level of the posterior margin of the hind ocelli, and Trichromothrips flavidus (Bhatti) also has these setae in a similar position ( Bhatti, 1978c, fig. 2). Moreover, Watanabeothrips and Neocorynothrips share the unusual state of three pairs of anteocellar setae. Bhatti (1978c) established Dovithrips as subgenus of Trichromothrips based on Dorcadothrips flavidus Bhatti. However , it is treated synonym of Trichromothrips here (also see Thysanoptera (Thrips) of the World—a checklist of L. A. Mound: http://www.ento.csiro.au/ thysanoptera / worldthrips.html).

Mycterothrips Trybom also shares with this group some character states, including dorsal apical setae of antennal segment I, and may also be closely related to the Trichromothrips genus­group; this relationship will be discussed elsewhere (Masumoto & Okajima, in prep.). Bathrips is similar to Trichromothrips in general appearance, but antennal segment I lacks dorsal apical setae and the male has abdominal tergum IX with a median pair of short and stout setae. Bathrips is not included in Trichromothrips genusgroup, despite the statement by Mound & Masumoto (2004) that these genera are closely related. The oriental genus Organothrips Hood , which has a similar aquatic habitat to Trichromothrips billeni (zur Strassen) and Pteridothrips pteridicola (Karny) , may also be distantly related to this genus­group because, despite their many characteristic features it has antennal segment I with dorsal apical setae.