The Recent non-marine ostracods of Tunisia: an updated checklist with remarks on their regional distribution patterns and ecological preferences

Abstract

Different lines of investigation have recently contributed to increasing the available knowledge about the invertebrates inhabiting inland waters of north Africa, but a comprehensive synopsis on Tunisian Ostracoda is missing to date. An updated checklist of Recent non-marine ostracods from Tunisia and data on their distribution is thus offered here, representing the most extensive survey on this crustacean group ever carried out in inland waters throughout the country. One-hundred-five sites covering various climate zones, from Mediterranean to desert areas, were sampled between 2002 and 2012. Most of the considered water bodies were temporary or ephemeral habitats, but a few permanent sites were sampled as well. Overall, 18 genera and 32 taxa of putative species rank were collected in the frame of this survey, among which nine species and five genera were new to Tunisian fauna. As a result of this study and based on previous investigations, nine families (Candonidae, Cyprididae, Cytherideidae, Darwinulidae, Ilyocyprididae, Leptocytheridae, Limnocytheridae, Loxoconchidae, Paradoxostomatidae), 29 genera and at least 45 species of non-marine ostracods are currently known for Tunisia, which thus prove to host the most diverse ostracod fauna among north African countries. The number of species occurring in a single sample varied from 1 to 4. The Eucypris virens complex was the most widespread taxon (58 records), followed by Heterocypris barbara (30 records), Heterocypris incongruens (22 records), and Sarscypridopsis aculeata (16 records). For some ostracod species, clear distributional gradients associated with different climatic conditions were observed. The affinities with adjacent Maghrebian ostracod faunas are discussed. This study confirms the crucial role played by marginal aquatic habitats for the conservation of biodiversity, in particular in arid and semi-arid regions.

The Diaptomidae (Copepoda, Calanoida) of Tunisia and the role of spatial and environmental factors as drivers of their distribution patterns

“…In sharp contrast with the similarity between Algerian and Tunisian diaptomid faunas, the Moroccan one is characterised by the occurrence of several taxa which are absent in central and eastern Maghreb (e.g., Diaptomus castaneti Burckhardt, 1920, D. kenitraensis Kiefer, 1926, D. cyaneus admotus Kiefer, 1974, Mixodiaptomus laciniatus s.l., Eudiaptomus chappuisi (Kiefer, 1926), and Hemidiaptomus maroccanus Kiefer, 1954), and by the absence of some taxa which are common in Algeria and Tunisia (e.g., Hemidiaptomus gurneyi, Mixodiaptomus lilljeborgi and Copidodiaptomus numidicus). This confirms a general biogeographical pattern which finds a clear east-west divide for both terrestrial and freshwater faunas in the Maghreb (e.g., Beddek et al, 2018;Marrone et al, 2017Marrone et al, , 2020a.…”

“…The same observation was reported for large branchiopods as well (Stoch et al 2016;Marrone et al 2016a, b), with up to 7 species co-occurring syntopically in some sites. This area thus confirms its role as a biodiversity hotspot for Tunisian inland water fauna, in agreement with Marrone et al (2020a) for ostracods, and Sicilia et al (2009) for amphibians. This high biological diversity is likely due to the geographical location of the flood plain, at the boundary of the rainy and substeppic zones, and to the existence of a local patchwork of water bodies with different hydroperiod and electrical conductivity.…”

“…Such a sharp pattern has been recently tested for other inland water taxa, with somehow controversial results, although the existence of a faunal latitudinal pattern in the country is rather evident (cf. Dumont et al, 1979;Turki and El Abed, 1999;Marrone et al, 2016a, b;Stoch et al, 2016;Marrone et al, 2020a).…”