Based on the relevant literature, six species of the genus Palaemonetes Heller, 1869, are known from the circum-Mediterranean region: P. antennarius (H. Milne Edwards, 1837); P. mesogenitor Sollaud, 1912; P. mesopotamicus Pesta, 1913; P. turcorum Holthuis, 1961; P. varians (Leach, 1814) and P. zariquieyi Sollaud, 1939.
The distinction of these species is based on the morphological features, as provided by various publications (eg., Sollaud, 1939; Zariquiey Alvarez, 1968; Lagardère, 1971; d’ Udekem d’ Acoz, 1999, Anastasiadou et al., 2002) (e.g.,). However, the descriptions of these species are still inadequate and/or vague and their distribution in the region as well as the presence of potential new taxa can not be investigated.
In order to clarify the taxonomic status of the genus Palaemonetes, numerous specimens from several localities of the circum-Mediterranean region have been collected. In all specimens, all main morphological features are currently examined and compared.
An initial analysis of the data collected in the course of this study revealed new, non-overlapping key characters that allow for easy and clear distinction of the six hitherto known species. Based on these new characters, the examination of specimens from different populations revealed the presence of four new species, which will be described in the near future. These species are: Palaemonetes n.sp. 1, from Kourna Lake, Crete, Greece; Palaemonetes n.sp. 2 from Rhodos Island, Greece and from the adjacent south-west Turkey; Palaemonetes n.sp. 3 from south Tunisia and, Palaemonetes n.sp. 4 from Egypt.
All the above species can be distinguished by using mainly the following morphological features: (a) the number and length of plumose setae at the distal end of telson; (b) the length ratio of posterior spines at the distal end of telson; (c) the arrangement of the lanceolate appendages on the ventrolateral margins of telson; (d) the exopod/ischiomerus length ratio at the third maxilliped; (e) the shape of the posterior end of the fifth abdominal pleuron and, (f) the appendix masculina/endopod length ratio in male individuals.
The updated geographical distribution of all Palaemonetes species in the circum-Mediterranean region is depicted and discussed.