Dugesia hepta Pala, Casu & Vacca, 1981

Stocchino, Giacinta Angela, 2018, 80 years of research on planarians (Platyhelminthes, Tricladida) from Sardinia, Italy: an annotated checklist, Zootaxa 4532 (4), pp. 539-552 : 540

Dugesia hepta Pala, Casu & Vacca, 1981

Dugesia hepta is a Sardinian endemic species restricted only to four hydrographic basins in the northwestern part of the island ( Pala et al., 1981; Stocchino et al., 2005) ( Fig. 1 ). The species is characterized by a peculiar chromosome number (2n = 14; n = 7), from which derives its specific epithet, which is unique within the Palaearctic Region. This chromosomal pattern is known only for Dugesia ryukyuensis Kawakatsu, Oki, Tamura & Sugino, 1976 , and D. batuensis Ball, 1970 , both from eastern Asia ( Ball, 1970; Kawakatsu et al., 1976). Dugesia hepta is also morphologically well distinguishable because of a peculiar dorsal ejaculatory duct with a lateral opening and a ventro-lateral penial fold. Among Dugesia species this dorsal course of the ejaculatory duct character is shared by only one other species viz. D. superioris Stocchino & Sluys, 2013 from Lake Ohrid in Albania ( Stocchino et al., 2013b, 2017c). Dugesia hepta populations are exclusively sexual with a life cycle comparable to that of other European dugesiids, such as D. ilvana Lepori, 1948 from Elba Island and D. gonocephala ( Dugès, 1830) from Central Europe (cf. Stocchino & Manconi, 2013). A recent origin of D. hepta from D. benazzii was suggested by molecular analysis ( Lazaro et al., 2009). This hypothesis is also supported by the coexistence of the two species at many localities in all of the Sardinian hydrographic basins inhabited by D. hepta .

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.