4
T. B. REYNOLDSON
11. THE TAXONOMY OF THE TRICLADS
The four species of triclad mainly involved in this work are Polycelis
nigra (Miill.), P . tenuis Ijima, Dugesia lugubris (0. Schmidt) and
Dendromelum lacteum (Miill.) (Fig. 2 ) . Phagocata vitta (Dug&) is also
reported in the field work and although it has a characteristic distribution no further work on it has been done in Britain, but Gislh (1946)
and Dahm (1949) have studied it in Sweden. Bdelloce.phala punctata
(Pallas), Planaria torva (Mull.) and Dugesia tigrinu (Girard) have been
recorded also but from too few lakes to provide any substantial clues to
the factors concerned in their distribution. Crenobia alpina (Dana) and
Polycelis felina (Dalyell) more typically stream species, have also been
recorded from lakes in Scotland and while this^ was probably related to
temperature in some way (Reynoldson, 1953), no further work on this
aspect has as yet been attempted.
There has been confusion over the taxonomic defhitions and identification of several of these species but the position has been greatly
clarified during the last five years. Originally, Polycelis nigra and
P . tenuis were confused but gradually from the work of Komarek (1927),
Lender (1936), Lepori (1950, 1955), Reynoldson (‘1948, 1958a), Lender
andMoigne (1960),Moigne(1962),Melander (1963),andBenazzi (1963a),
these two species can now be recognized easily by penis structure.
Pp
.9m
Po&cefis
Polycelis
Dugesia
Dendrocoelum
Pbogocofo
FIQ. 2. The five lake species of triclad; vertical linen show the relative, average size of
adults.
nigra
fenuis
lugubris
/acfeum
ViffO
T. B. REYNOLDSON
11. THE TAXONOMY OF THE TRICLADS
The four species of triclad mainly involved in this work are Polycelis
nigra (Miill.), P . tenuis Ijima, Dugesia lugubris (0. Schmidt) and
Dendromelum lacteum (Miill.) (Fig. 2 ) . Phagocata vitta (Dug&) is also
reported in the field work and although it has a characteristic distribution no further work on it has been done in Britain, but Gislh (1946)
and Dahm (1949) have studied it in Sweden. Bdelloce.phala punctata
(Pallas), Planaria torva (Mull.) and Dugesia tigrinu (Girard) have been
recorded also but from too few lakes to provide any substantial clues to
the factors concerned in their distribution. Crenobia alpina (Dana) and
Polycelis felina (Dalyell) more typically stream species, have also been
recorded from lakes in Scotland and while this^ was probably related to
temperature in some way (Reynoldson, 1953), no further work on this
aspect has as yet been attempted.
There has been confusion over the taxonomic defhitions and identification of several of these species but the position has been greatly
clarified during the last five years. Originally, Polycelis nigra and
P . tenuis were confused but gradually from the work of Komarek (1927),
Lender (1936), Lepori (1950, 1955), Reynoldson (‘1948, 1958a), Lender
andMoigne (1960),Moigne(1962),Melander (1963),andBenazzi (1963a),
these two species can now be recognized easily by penis structure.
Pp
.9m
Po&cefis
Polycelis
Dugesia
Dendrocoelum
Pbogocofo
FIQ. 2. The five lake species of triclad; vertical linen show the relative, average size of
adults.
nigra
fenuis
lugubris
/acfeum
ViffO