Schmidtea polychroa S. polychroa 80 years of research on planarians (Platyhelminthes, Tricladida) from Sardinia, Italy: an annotated checklist Stocchino, Giacinta Angela Zootaxa 2018 2018-12-20 4532 4 539 552 7WTBL (Schmidt, 1861) Schmidt 1861 [151,609,223,250] Rhabditophora Dugesiidae Schmidtea GBIF Animalia Tricladida 4 543 Platyhelminthes species polychroa    Schmidtea polychroais 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. polychroafrom Sardiniaby 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 typeof development is unknown ( Casu et al., 1982) ( Fig. 2).