The terrestrial isopod fauna of the Maltese Islands

Abstract

This study is the result of four years field and laboratory reasearch work on the oniscoidean isopod fauna of the Maltese Islands. In all 49 terrestrial isopods were identified of which 2 genera, Trichorhina and Proporcellio are new records for the islands. Seven species are also recorded for the first time, namely, Tylos Iatreillei europaeus, Haplophtalmus danicus, Trichorhina paolae, Trichorhina bonadonai, Proporcellio quadriseriatus, Armadilloniscus littoralis and Armadillium. The latter species was found to be new to science and is in the process of being described formally. The identity of some previously dubious species is also clarified. An illustrated dichotomous key for the identification of oniscoidean isopods present in the Archipelago is also supplied. The principal synonyms, previous records from the literature and material examined during the present study· are given for each species, together with notes on taxonomy, morphology <including maximum mal~ and female body length>, reproductive biology, ecology and geographical distribution, based on field and laboratory observations. A diagram of the whole animal of at 1 east one representative from each. genus is al so given together with local distribution maps for each species on one square kilometre grids. This is to update and extend the information already given by Caruso and Lombardo (1982) and Caruso et a.I. ( 1987). The data were analysed to discover if there are any general - trends as regards habitat/microhabitat preferences of the individual species, sex ratio, brood frequency, myrmecophylic associations and abundance and distribution both within the Maltese Archipelago and in the surrounding islands and mainlands. Through a preliminary biogeographical analysis of the species present it is shown that the isopod fauna of the Maltese Archipelago has a strong affinity with that of Sicily and the existence of a Hyblean-Maltese territory already hypothesized by La Greca (1957) is also confirmed.