A New Lignyodes Dejean, A New Representative of the Genus and the Tribe Lignyodini from the Eastern Palaearctic Region (Coleoptera: Curculionidae)

A new species of the genus Lignyodes Dejean, which is a new representative of the genus and the tribe Lignyodini Bedel, was discovered in Japan on the eastern periphery of the Palaearctic region. It is described herein as L. japonicus new species. The discovery of this species shows the discontinuous distribution of this genus in East Asia –North America, and Europe, with the Bering Arc relationship in the temperate region of the northern hemisphere.

This species is very rare in collections and no biological information is available. The probable host and distribution in Japan are predicted from previous records of related species. In the northern hemisphere, the East Asian biota, especially in the temperate area, may have an important role in understanding the biogeography of the Holarctic region and may have great diversity, with many endemic taxa.

For example, in phytogeography this area is recognized as the Sino-Japanese Region and is characterized by its richness in endemic families and genera, and also the Asian center of diversity for genera belonging to the classic Arcto-Tertiary pattern of disjunction between eastern Asia and North America and a few other localized parts of the world (Boufford and Ohba 1998). However, the insect survey in this area is imperfect compared with other regions such as Europe and North America, and many important discoveries remain.

The identification of a small weevil assigned to the genus Lignyodes Dejean from Japan, reported here, is an example beyond the previous knowledge of this group that is an example of a discontinuous distribution between East Asia, North America and Europe in temperate regions of the northern hemisphere. Weevils of the genus Lignyodes are classified in the tribe Lignyodini Bedel or Lignyodina of the Tychiini Thomson according to the recent catalogue by Alonso-Zarazaga and Lyal (1999).

Lignyodes is divided into three subgenera: Lignyodes s. str., Chionanthobius Pierce and Neotylopterus Clark et al. and is known to be associated with the plant family Oleaceae (Clark 1982). All three subgenera occur in North America but L. (Lignyodes), extends its distribution into Europe. Lignyodes (Lignyodes) is found mainly in the eastern part of North America.

A new species discovered in Japan is assigned to L. (Lignyodes). The discovery of this new species from Japan extends the distribution of the genus and that of the tribe/ subtribe. Lignyodini (-ina) is predominantly New World and no member was known previously from the eastern Palaearctic region.

Further discoveries may be expected if we consider the host plant distribution because most species of L. (Lignyodes) are known to be associated with ash trees of the genus Fraxinus and the larvae develop in seeds of these plants (Clark 1980; Clark and Lodos 1981). In this paper, we describe a new Lignyodes species from Japan and discuss the distribution of this genus with comments on its affinity with other relatives from the point of view of comparative morphology.

This species is very rare in collections and only four specimens have been collected from a limited area in central Japan. No biological information is available, except that one adult came to light and an unlikely host record from Quercus phillyraeoides A. Gray (Fagaceae) is recorded. Thus, we consider the distribution of this species in Japan in relation to the previous host records and distribution and suggest it also may occur in other parts of East Asia.

Abbreviations used in this study are as follows: ELKU: Entomological Laboratory, Kyushu University, Fukuoka; IM: I. Matoba collection, Wakayama.