By Johannes Frisch, MfN Berlin, Germany
The rove beetles (Coleoptera: Staphylinidae) comprise more than 45.000 named species worldwide and thus constitute the most speciose beetle family. The majority of rove beetles are epigeal dwellers of the uppermost soil layer and herbaceous litter of humid habitats such as woods, pastures, riverbanks, bogs and swamps. The Staphylinidae are considered as monophyletic mainly according to the characteristic short elytra, secondary sclerotization of abdominal tergites and an apomorphic set of abdominal glands.
The rove beetle genus Scopaeus Erichson, 1839 (Staphylinidae: Paedrinae) is one of the target groups of the Indobiosys Project. The taxon is distributed all over the world and mega-diverse particularly in the tropics and subtropics. Only about 450 species of Scopaeus have been described until now, but the number of unnamed species is many times larger judging from unidentified museum samples.
The majority of Scopaeus species are riparian dwellers of damp sand and gravel of banks of various kinds of freshwater habitats, preferably the margins of rivers and streams. Both abundance and diversity of Scopaeus strongly depends of uncanalized running waters with a variety of natural bank structures.
The Scopaeus fauna of the Oriental Region and Indonesia is very poorly known. Up to now, only a few dozens of species were described from this zoogeographic realm, the majority of which prior to 1950. The first Oriental species were described by Motschulsky (1858) and Kraatz (1859) mainly from India, followed by Cameron (e.g. 1930, 1936), who described the first species from Malaysia, Singapore and Indonesia. Many years later, Frisch (2003, 2005) named some more Oriental Scopaeus, among them the Indonesian S. wunderlei, S. sarawakensis, S. sundaensis and S. baliensis.
The previous field work of the Indobiosys Project yielded a great diversity of Scopaeus along rivers and streams of the Halimun Salak National Park and surroundings. Besides four already named species (S. filiformis Wollaston, S. limbatus Kraatz, S. wunderlei Frisch, S. sundaensis Frisch), 15 undescribed species were discovered up to now. This great diversity of Scopaeus was not expected in the limited range of the Halimun-Salak Nationalpark and clearly points to a great diversity of the genus in all of Indonesia.