Earthworms represent one of the most important animal groups affecting the structure and chemical composition of soils and the distribution of plant nutrients in them. Their influence is especially prominent in the areas south of the quaternary ice sheet border, where earthworms constitute the main components of the soil fauna and where large-bodied species occur.
Despite their importance, our knowledge of earthworms' systematics, biology, and ecology in the Eastern Mediterranean region is far from complete. No systematic earthworm survey has been conducted in Israel or in the adjacent countries. Sources for previously published data were occasional earthworm collections assembled as a by-product of other investigations.
Recently, a methodical earthworm survey was carried out as part of a long-term evolutionary-ecological project at a microsite (0.4 km2), Lower Nahal Oren, Mt. Carmel, Israel. The results showed relatively high local earthworm diversity and revealed two previously undescribed species. These results inspired the present intensive investigation of the earthworm fauna of Israel and the Sinai Peninsula (Egypt), in which ca. 110 localities in Israel and the Sinai were sampled.
According to our and literature records, 30 species, 14 genera and five families of earthworms are known to be present in the Levantin region (a stretch of land about 150 km wide, wedged between the sea and the Syrio-Arabian deserts, stretching from the mouth of the river Orontes and the Amanus and Taurus mountains in the north, to the Isthmus of Suez in the south).
Ap. caliginosa and Eis. tetraedra are represented by two (forms ?) subspecies each. By excluding introduced species, the autochtonous earthworm fauna of the Levant includes 18-19 (60%-63%) species all belonging to the family Lumbricidae. We regard Ap. jassyensis and D. veneta as being autochtonous and D. hortensis as being introduced in the Levant, nevertheless with certain doubts. In spite of our efforts, we have not been able to re-collect A. aharonii Stephenson, 1922 and A. georgii Michaelsen, 1890. There is no doubt that A. aharonii, is a valid species of which the holotypus collected in Rehovot, Israel is preserved in the British Museum. A. georgii Michaelsen, 1890 was mentioned from the Levant a few times (Rosa 1893, Michaelsen 1926), but, in our opinion, the presence of this Atlanto-Mediterranean species in the Levant is not very probable, unless it was introduced.
Eight to eleven species (42%-61%) of the autochtonous ones are endemic to the Levant. In three species (B. syriacus, D. hauseri, and D. orientalis), the taxonomic status and consequently the distribution need to be revised because of the following problems: (i) the specimens of B. syriacus collected in Anatolia are, in comparison with the Levantine ones, darker, bigger, possess more segments, and have thicker septa (Omodeo & Rota 1989). (ii) The specimens of D. hauseri from Israel, in comparison with the Anatolian ones, possess an additional pair of small vesicula in the segment x (Csuzdi et al. 1999a). (iii) It is unclear to which species refer D. orientalis described from Armenia by Perel (1979) since she erroneously regarded D. orientalis as synonymous to D. ressli (Csuzdi et al. 1999b). In addition, the Holomediterranean D. byblica probably represents a superspecies complex (Zicsi 1982).
Interestingly, ten autochtonous Levantine species (53%-59%) belong to the genus Dendrobaena in contrast with two species in the genus Bimastos and only one species in the genera Allobophora (s.l.), Eiseniella, Helodrilus, Murchieona and Octodrilus Dendrobaena species also represent 55%-88% (6-7 species) of the Levantine endemic species.