Turbellarian taxonomic database

Abstract / Notes

The triclad fauna of certain Piedmontese streams, especially in the Susa and Lanzo valleys, is descr. from
ecological and successional aspects. The triclad population consists essentially of Planaria alpina, P.
gonocephala, and Polycelis cornuta. P. gonocephala, occurring in lower reaches of streams, is replaced by
Polycelis cornuta in higher regions and this by P. alpina. The last is stenothermic, adapted to life at low
constant temps.; the first 2 live in warmer zones. P. gonocephala is eurythermic, with a maximum of
34[degree]. In the Susa valley, P. alpina occurs at 2105m., at Madonna della Cotolovier. In the zone
Alpignano and Avigliana (400m.) P. alpina occurs, some being spotted. In the zone S. Ambrogio (353m.) and
Novaretto (362m.) Pol. cornuta and Pol. nigra occur, a race of P. cornuta normally multiplying by fission
being here. At Sala (600m.) a Planaria, morphologically P. gonocephala but of remarkable size, was found,
some sexual, others in fission, the water temp. being 13.5[degree]-15[degree] maximum. Fission usually was
postpharyngeal but in a few prepharyngeal. From S. Antonino di Susa (380m.) P. alpina only occurs in the
stream descending the "Pian del Rocco," and it is the only planarian from Bussoleno (435m.) to Madonna della
Saletta (1350m.). In the Sangone stream, rare Pol. nigra and fairly numerous well developed sexually mature
Pol. cornuta occur. In the Lanzo valley, at Bogliano (800m.), a rich fauna of Pol. cornuta and some
Dendrocoelum lacteum occur, the former being diffused throughout the brooks of Pes-sinetto and Traves. At
Mondrone (1260m.) numerous Pol. cornuta and fairly numerous PL alpina are present, the latter also being
widely spread in the valley of Aosta. The large species of Planaria from near S. Ambrogio is placed near P.
gonocephala. Its relation to P. subtentaculata is discussed, this species being considered by Draparnaud as
oviparous in spring, gernmiparous in summer, with great powers of regeneration and fission. The external
morphology of the large Planaria has been compared with that of PL gonocephala from Elba and with Pl.
subtentaculata from Rapallo; its affinities, from all considerations, being with the former.

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