Schmidtea polychroa ( Schmidt, 1861 )

Stocchino, Giacinta Angela, 2018, 80 years of research on planarians (Platyhelminthes, Tricladida) from Sardinia, Italy: an annotated checklist, Zootaxa 4532 (4), pp. 539-552 : 543

Schmidtea polychroa ( Schmidt, 1861)

Schmidtea polychroa is distributed mainly in the northern part of the island in large hydrographic basins as well as small rivers ( Fig. 2 ). On the basis of karyological and reproductive characteristics four biotypes (A, B, C, D) have been recognized within the species ( Benazzi, 1957; Benazzi & Benazzi Lentati, 1976).

The first record of S. polychroa from Sardinia by Benazzi (1957) reported the presence of biotype A, which is amphimictic and diploid (2n = 8; n = 4). Pala and co-workers ( Pala et al., 1980b; Casu et al., 1982; Vacca et al., 1988, 1993) highlighted the widespread distribution of biotype A and found also several populations characterized by triploid (3n = 12; n = 4) and tetraploid chromosome sets (4n = 16; n = 4), corresponding to the gynogenetic, asynaptic biotypes C and D, respectively. Biotype B was never found in Sardinia. Further, a new pentaploid biotype (5n = 20; n = 4) was found in a population from River Temo for which the type of development is unknown ( Casu et al., 1982) ( Fig. 2 ).

Figures

FIGURE 2. Geographic distribution of species of the genus Schmidtea and Girardia recorded from Sardinia. 1, Rio Fiume Santo; 2, Rio Mannu di Portotorres; 3, Rio S. Miali; 4, Fiume Silis; 5, Rio Pedrasdefogu; 6, Rio Lu Bagnu; 7, Fiume Coghinas; 8, Rio S. Stefano, Caprera Island National Park; 9, Rio Cuga; 10, Rio Calvia; 11, Fiume Temo; 12, unnamed temporary rivulet near Su Peltusu Cave; 13, Rio Fraigada; 14, Fiume Tirso; 15, Rio di Siniscola; 16, Rio Berchida; 17, unnamed rivulet affluent of Rio Mannu di Milis; 18, temporary pond of Giara di Tuili; 19, Pauli Perdosu temporary pond of Giara di Gesturi; 20, Rio Mannu di Cagliari; 21, Rio Flumentepido. New records are indicated by asterisks.