Turbellarian taxonomic database

Record # 16122
Timoshkin OA (1997)
Taxonomic revision of the relict turbellarian group Prolecithophora Protomonotresidae from Lake Baikal (Plathelminthes): Description of Porfirievia n. gen., six new species of the genus and notes on the phylogeny of the Baicalarctiinae. In: Wada E...
New Scope on Boreal Ecosystems in East Siberia,151-179

Abstract / Notes

The descriptions of  Porfirievia, a new genus of Baikal endemic Prolecithophora and six new species of the
genus are given. The species of the new genus differ from the representatives of two previously described
genera of Baikal prolecithophorans, Friedmaniella and Baicalarctia, by the following main characteristics: a)
pharynx constructed as a pharynx plicatus with poorly developed muscles, b) extremelly numerous epidermal
rhabdoids, c) the lateral branches of the vitellaria extending from the rostral to the caudal end of the
body, d) small body size of sexually mature worms, etc. A close morphological similarity of the three genera
is briefly demonstrated; this provides evidence about: 1) the monophyletic and autochthonous origin of the
subfamily Baicalarctiinae in the lake; 2) the repeated and independent occurrence of a separate mouth tube
(pharynx pocket) and genital pore within Prolecithophora Separata, which makes this feature invalid for
phylogenetic analysis of the group; 3) the non-monophyletic origin of the Prolecithophora Separata. The
phylogeny of the Baicalarctiinae based on comparative-morphological and molecular-biological analyses is
discussed. Porfirievia is considered the most primitive genus of Baikal endemic prolecithophorans, close to
their ancestral form; on the other hand, Baicalarctia should be considered as the youngest and most
specialized genus among them. It is shown that food specialization drastically changed the general
morphological organization and structure of the digestive system in the Baicalarctiinae, and thus played one
of the most important roles in the evolution of this species flock in Baikal. 


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