Tomostethus nigritus (Fabricius, 1804)

Ryoo, Seung-Woo, Min, Jin-Young, Son, Seok-Yoon, Choi, Baek-Yong, Choi, Juho & Min, Kyoung-Bok, 2022, Taxonomic Notes and New Distribution and Host Plant Records for Sawflies and Woodwasps (Hymenoptera, Symphyta) of Japan VII, Bulletin of the National Museum of Nature and Science. Series A, Zoology 48 (4), pp. 193-213 : 209

Tomostethus nigritus (Fabricius, 1804)

Japanese name: Yachidamo-habachi

( Fig. 11 )

Larva. Early instar ( Fig. 11D ): pale gray, with thoracic legs gray. Final instar ( Fig. 11E, F ): head brown with black markings; thorax and abdominal segment 1 pale yellow; thoracic legs black; abdominal segments 2–10 pale gray, pale yellow on tergum 8.

Material examined. Honshu: Tochigi Pref.: 2 $, Nakagawa, Wami , 36°47′N 140°10′E, coll. larvae on Fraxinus sieboldiana , 24. IV. 2021, mat. 5, 7. V., em. 11, 12. IV. 2022, S. Ibuki ( Fig. 11 ) .

Host plant. Oleaceae : Fraxinus sieboldiana Blume in Japan (new record); F. excelsior L. and F. mandshurica Rupr. in Korea ( Okutani, 1967b); F. excelsior in Europe ( Lorenz and Kraus, 1957).

Remarks. In the paper entitled lFood plants of Japanese Symphytaz, Okutani (1967b) listed Fraxinus excelsior and F. mandshurica as the hosts of this sawfly, but he stated that those hosts were recorded in Korea. This is the first report of a host record for the Japanese population.

The above two Japanese females agree with the European specimens of Tomostethus nigritus , judging from Verheyde and Sioen (2019) and Lacourt (2020) (compare Fig. 11A–C with images in Taeger et al., 2018 and fig. 1 in Verheyde and Sioen, 2019). However, the Japanese larva is quite different from the European larva in color. According to Lorenz and Kraus (1957) and Verheyde and Sioen (2019), the European late instar larva has light green head, trunk and thoracic legs and a pair of whitish dorsal stripes under the cuticle on the trunk (fig. 3 in Verheyde and Sioen, 2019; fig. 1, p. 353 in Macek et al., 2020). Conversely, the Japanese late instar larva has a dark head, black legs and a pale yellow and pale gray trunk ( Fig. 11E, F ).

Figures

Fig. 11. Tomostethus nigritus: A–C, Female, head in anterior view, whole body in dorsal and ventral views; D, early instar larva, 25. IV. 2021; E, F, final or final feeding instar larva, 1. V. 2021. A–C, Photographed by Hara; D–F, photographed by Ibuki.