Dugesia liguriensis De Vries, 1988

Stocchino, Giacinta Angela, 2018, 80 years of research on planarians (Platyhelminthes, Tricladida) from Sardinia, Italy: an annotated checklist, Zootaxa 4532 (4), pp. 539-552 : 541

Dugesia liguriensis De Vries, 1988

A peculiar case concerns a previously presumed fissiparous population of D. benazzii from the Rio Mannu di Cagliari in southern Sardinia ( Fig. 1 ). Individuals have a triploid karyotype with 24 chromosomes and never sexualized under long-term laboratory conditions (M. Pala and G.A. Stocchino pers. obs.). Surprisingly, a recent molecular analysis assigned this population to D. liguriensis , together with two other asexual triploid (3n = 24; n = 8) populations from northeastern Spain and Liguria ( Lazaro et al., 2009), a species firstly reported from Liguria and later also from Piedmont (northern Italy) (cf. Stocchino et al., 2013a). The sexual population from Piedmont has a diploid chromosome complement of 2n = 16; n = 8 (cf. Lazaro et al., 2009). Therefore, the species is presumably characterized by both sexual diploid as well as asexual triploid populations.

In view of the present disjunct distribution of D. liguriensis , the single population from Sardinia could be considered as the sole representative on the island of a population complex that formerly had a much wider distribution, involving the Proto-Ligurian microplate, before the Corsica-Sardinia block broke up during the late Oligocene and Miocene. Experiments under lab conditions to stimulate sexualization of the Sardinian specimens are in progress with the aim to resolve the taxonomic status of this Sardinian population also at the morphological level.

Figures

FIGURE 1. Geographic distribution of species of the genus Dugesia recorded from Sardinia. 1, Rio d’Auteri reservoir, Asinara Island National Park; 2, Rio Mannu di Portotorres; 3, Fiume Silis; 4, Rio Lu Bagnu; 5, Fiume Coghinas; 6, Fiume Liscia; 7, spring and wells on the Tavolara Island Protected Area; 8, springs and unnamed rivulets on the Molara Island Protected Area; 9, Rio Su Lernu; 10, Rio Cuga; 11, Rio de sa Pazzosa; 12, Rio Torre Argentina; 13, Fiume Temo; 14, Sa Ucca ‘e su Peltusu Cave; 15, Rio S’Abba Mala; 16, Rio Mannu di Scano di Montiferro; 17, Rio Santa Caterina; 18, Fiume Tirso; 19, Su Cantaru Spring, Rio di Siniscola basin; 20, Fiume Cedrino; 21, Rio Osalla; 22, Rio Mannu di Milis; 23, Rio di Monte Arci; 24, Fiume Flumendosa; 25, Rio Mannu di Cagliari; 26, Fiume Quirra; 27, Rio Acqua ‘e sa Murta, S. Antioco Island; 28, Rio Triga, S. Antioco Island; 29, Rio ‘e sa Canna, S. Antioco Island; 30, Rio Flumentepido; 31, Rio Gutturu Mannu; 32, Rio Geremeas. New records are indicated by asterisks.