Aleochara (Emplenota)

Introduction

The subgenus Emplenota includes eight seashore-dwelling species. They occur in Europe, East Asia and North America (Atlantic and Pacific coasts).

Characteristics

Emplenota species are characterized by: elongate, subparallel, more or less flattened body; very distinct microsculpture, especially on the forebody; hypomera visible in lateral view; mesosternum not or incompletely carinate; and median lobe of the male aedeagus with a pair of ventral processes. The pattern of pronotal pubescence is not uniform among the species of this subgenus (ASSING 1995, WELCH 1997), but it may be used to distinguish the Western Palaearctic species from the externally similar species of the Western Palaearctic subgenus Polystomota (see LOHSE 1984, 1989).

Identification Guides

Nearctic species can be identified with the key of KLIMASZEWSKI (1984). Palaearctic species were revised by ASSING (1995), and a further species was added by WELCH (1997) (who, however, does not distinguish between Emplenota and Polystomota). European keys published before LOHSE (1984) should not be used for identification, since radical nomenclatorial and taxonomic changes regarding the European species of both Emplenota and Polystomota were established in this paper, and using the old names may lead to confusion.

Bionomics

All Emplenota species live on seashores, where they are found under decaying seaweed and debris, and occasionally on carrion. The only species whose development and hosts are known is A. obscurella. The hosts belong to the families Sepsidae, Coelopidae and Anthomyiidae (PESCHKE & FULDNER 1977, MAUS et al in prep.). The larvae pupate inside of the host puparium.

Discussion of Phylogenetic Relationships

The phylogenetic relationships within the subgenus have not been investigated. However, ASSING (1995) assumed, based on similarities of the patterns of pronotal pubescence, that the Eastern Asian species (i. e. A. (E.) fucicola and A. (E.) puetzi) are more closely related to the North American species (i. e. A. (E.) littoralis, A. (E.) pacifica and A. (E.) curtidens) than to the European species (i. e. A. (E.) obscurella, A. (E.) albopila and A. (E.) phycophlia). Biogeographic considerations may support the existence of three major evolutionary lineages (an European, an East Asian and an American lineage).

References

Assing, V. 1995. The Palaearctic species of Emplenota Casey, Polystomota Casey, Triochara Bernhauer and Skenochara Bernhauer & Scheerpeltz, with descriptions of three new species (Coleoptera, Staphylinidae, Aleocharinae). Beitr. Ent. 45(1): 217-237

Klimaszewski, J. 1984. A revision of the genus Aleochara Gravenhorst of America north of Mexico (Coleoptera: Staphylinidae, Aleocharinae). Mem. Ent. Soc. Canada 129: 1-211

Lohse, G.A. 1984. 14. Nachtrag zum Verzeichnis der mitteleuropaeischen Kaefer. Ent. Bl. 80(2-3): 143-152

Lohse, G.A. 1989. 23. Familie Staphylinidae (II) (Aleocharinae). In: Lohse, G.A. & W.H. Lucht: Die Käfer Mitteleuropas, Band 12 (1. Supplementband). Goecke & Evers, Krefeld: 346 pp.

Maus, Ch., B. Mittmann & K. Peschke in prep.. Survey of host records of parasitoid Aleochara species (Coleoptera: Staphylinidae) attacking cyclorrhaphous fly puparia: Review and new investigations.

Peschke, K. & D. Fuldner 1977. Uebersicht und neue Untersuchungen zur Lebensweise der parasitoiden Aleocharinae (Coleoptera: Staphylinidae). Zool. Jahrb. Syst. 104: 242-262

Welch, R.C. 1997. The British species of the genus Aleochara Gravenhorst (Staphylinidae). Coleopterist 6(1): 1-45