Turbellarian taxonomic database

Abstract / Notes

The regeneration of eyes in triclads is considered as an index of a capability for regeneration of
individual.  Fifteen species were studied in various parts of the world.  Only in 3 cases less than 50
individuals were
used. Depending upon the size of the species, the animals were cut in 4-8 equal pieces which were placed in
separate dishes according to the body level, allowed to regenerate for 12 days or longer and examined for
presence of eyes. The numerical results are given on percentage basis. The data indicate that there are 5
groups in respect to capability for regeneration at different levels along the main body axis I, Bdelloura
group in which there is no regeneration of eyes at any level of the body. To this group belong B. Candida
(Woods Hole, Mass.) and possibly Syncaelidium (Woods Hole), both ectoparasites. II, the Dendrocoelum group
in which the regeneration is limited to regions anterior to the pharynx, only single antero-posterior
gradient
present. To this group belong D. lacteum (Tihany, Hungary), Procotila fluviatilis (Woods Hole) and
Procerodes wheatlandi (Woods Hole). III, the Phagocata group regenerates best in the anterior region, this
capability
decreases in the posterior direction. Only single anteroposterior gradient is present. To this group belong
P. gracilis (Woods Hole), Polycelis nigra (Kaunas, Lithuania), Polycelis tenuis (Tihany), Planaria lugubris
(Kaunas), P. torva (Kaunas). IV. P. dorotocephala group regenerates best at the ends of both the anterior
and the posterior regions and least in the middle of the body. To this group belong P. dorotocephala, P.
lata,
P. sp. (all Chicago) and P. maculata (Woods Hole). V, the P. velata group regenerates equally well at all
levels of the body. No gradient or a weak double gradient is present. To this group belong P. velata
(Chicago) and
P. hymani (Philippines). The latter possibly may belong to the IV group.

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