80 years of research on planarians (Platyhelminthes, Tricladida) from Sardinia, Italy: an annotated checklist Author Stocchino, Giacinta Angela text Zootaxa 2018 2018-12-20 4532 4 539 552 journal article 27733 10.11646/zootaxa.4532.4.5 38d5db9a-4c71-408d-84d2-5b98fd8afa0d 1175-5326 2615649 807B317B-D883-439F-97B9-B0C0F09D9666 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 ).