Numerous errors and confusion in the literature concerning the genus Trichogramma in Japan have necessitated a formal review of this genus. This review corrects and updates Trichogramma host and distribution records from Hokkaido to the Ryukyu Islands, redescribes and designates a lectotype for T. jezoense Ishii, records two Trichogramma species new to Japan (T. ostriniae Pang and Chen and T. lingulatum Pang and Chen) and describes three new species (T. yabui Honda and Taylor, T. okinawae Honda, and T. aomoriense Honda). Additionally a key to the species is provided for the 14 known Japanese species as are ITS-2 DNA sequences and SEM micrographs of male genital capsules for the majority of the species to aid biocontrol workers in Trichogramma identification.Key words: Taxonomy; species description; Japanese Trichogramma; DNA sequence; male genital capsule * To whom correspondence should be addressed at: E-mail: jhonda@email.sjsu.edu † Present address: Department of Entomology, 320 Morrill Hall, University of Illinois, 505 S. Goodwin Ave., Urbana, IL 61801, USA ‡ Present address: 349 Asano, Munakata 811-3415, Japan DOI: 10.1303DOI: 10. /aez.2006 never verified. Test releases using Hirai's cultured material was later used for O. furnacalis control in corn fields in 1992 -93 (Yoshizawa, 1995. Trichogramma brassicae Bezdenko, another imported species of Trichogramma, was used in test releases for the control of M. brassicae in sugar beet fields in 1997 (Iwasaki et al., 1998) and for the control of P. xylostella in greenhouses in 1999 (Miura et al., 2001). Again their establishment has not been confirmed.Despite the considerable international attention that Trichogramma has received as an important biological control agent, its taxonomy remains inadequately understood for a number of reasons. For example, the collection and curation of these minute (approximately 0.5 mm) parasitic wasps has proven difficult and greatly slowed the accumulation of study material . Moreover, the early disregard of type specimens has caused much confusion in the literature. Because a number of type specimens are lost, unusable, or described inadequately, many species names have been applied incorrectly and inconsistently in the literature (Pinto et al., 1978;Pinto and Stouthamer, 1994;Pinto, 1999). Finally, Trichogramma taxonomy also suffered from an absence of consistent distinguishing morphological characters (Pinto, 1999). This dilemma was partially resolved by Nagarkatti and Nagaraja (1971) who discovered the importance of the male genitalia as a diagnostic taxonomic character. DNA sequences have also been proposed as an aid to identification and used in a number of studies to characterize Trichogramma species (Pinto et al., 1997;Silva et al., 1999;Stouthamer et al., 1999).The history of Trichogramma taxonomy in Japan exemplifies many of the taxonomic difficulties prevalent in the genus. For example, Nakagawa (1900) was the first to record Trichogramma from Japan by describing in morphological detail, the adult of a Trichogra...

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A new species of Trichogramma that parasitizes Sialis melania eggs is described as Trichogramma tajimaense Yashiro, Hirose and Honda, sp. nov. from Japan. Its phylogenetic position is based on a DNA‐based analysis, and data regarding its male wing polymorphism are also presented. The view that T. tajimaense is closely related to T. semblidis, another parasitoid of Sialis eggs, is supported by the results of a phylogenetic analysis, as well as by the biological and morphological similarities between both species. Trichogramma tajimaense is also similar in male wing polymorphism to T. kurosuae, a gregarious egg parasitoid of the lepidopteran Ivela auripes, as both Trichogramma species exhibit male wing trimorphism (fully alate, brachypterous and apterous forms) in contrast to the male wing dimorphism (fully alate and apterous forms) of T. semblidis. However, no phylogenetic analysis reveals a close relationship between T. tajimaense and T. kurosuae, and a difference exists between these two species in the mean percentage of flightless (brachypterous and apterous) males that emerge from a host egg mass; 96% of T. tajimaense males are incapable of flight, whereas about 50% of T. kurosuae males are flightless. Because all or almost all males of T. semblidis parasitizing Sialis eggs are apterous, T. tajimaense is more similar to T. semblidis than to T. kurosuae in the proportion of flightless males. In addition, male wing polymorphisms of Trichogramma in relation to mating systems could also show a similarity between T. tajimaense and T. semblidis when considering both species as quasi‐gregarious parasitoids of Sialis eggs.