. Filling a gap in the phylogeny of flatworms: relationships within the Rhabdocoela (Platyhelminthes), inferred from 18S ribosomal DNA sequences. -Zoologica Scripta , 35 , 1-17. The phylogeny of the Rhabdocoela, a species-rich taxon of free-living flatworms, is reconstructed based on complete 18S rDNA sequences. The analysis includes 62 rhabdocoels and 102 representatives of all major flatworm taxa. In total, 46 new sequences are used, 41 of them from rhabdocoel species, five from proseriates. Phylogenetic analysis was performed using maximum parsimony and Bayesian inference. Clade support was evaluated with parsimony jackknifing, Bremer support indices and Bayesian posterior probabilities. The resulting cladogram corroborates that the Rhabdocoela is monophyletic, but its sister group remains uncertain. The 'Dalyellioida' and the 'Typhloplanoida', both former rhabdocoel subtaxa, are polyphyletic. Within the Rhabdocoela the monophyletic Kalyptorhynchia, characterized by a muscular proboscis, forms the sister group of all other rhabdocoels. The Schizorhynchia is a monophyletic subtaxon of the Kalyptorhynchia, with the split proboscis as a synapomorphy. Except for the Dalyelliidae and the Typhloplanidae, both freshwater taxa, none of the 'families' previously included in the 'Typhloplanoida' and the 'Dalyellioida' appears to be monophyletic. As a result of this analysis, three existing and four new taxon names are formally defined following the rules of the Phylocode.
In this study we elaborate the phylogeny of Dalytyphloplanida based on complete 18S rDNA (156 sequences) and partial 28S rDNA (125 sequences), using a Maximum Likelihood and a Bayesian Inference approach, in order to investigate the origin of a limnic or limnoterrestrial and of a symbiotic lifestyle in this large group of rhabditophoran flatworms. The results of our phylogenetic analyses and ancestral state reconstructions indicate that dalytyphloplanids have their origin in the marine environment and that there was one highly successful invasion of the freshwater environment, leading to a large radiation of limnic and limnoterrestrial dalytyphloplanids. This monophyletic freshwater clade, Limnotyphloplanida, comprises the taxa Dalyelliidae, Temnocephalida, and most Typhloplanidae. Temnocephalida can be considered ectosymbiotic Dalyelliidae as they are embedded within this group. Secondary returns to brackish water and marine environments occurred relatively frequently in several dalyeliid and typhloplanid taxa. Our phylogenies also show that, apart from the Limnotyphloplanida, there have been only few independent invasions of the limnic environment, and apparently these were not followed by spectacular speciation events. The distinct phylogenetic positions of the symbiotic taxa also suggest multiple origins of commensal and parasitic life strategies within Dalytyphloplanida. The previously established higher-level dalytyphloplanid clades are confirmed in our topologies, but many of the traditional families are not monophyletic. Alternative hypothesis testing constraining the monophyly of these families in the topologies and using the approximately unbiased test, also statistically rejects their monophyly.
A morphological and taxonomic account of the genus Trigonostomum is provided. All known species are discussed and briefly re‐described where necessary. Seven new species are described: T. franki from Curaçao, Florida (USA), the East African Coast and New Caledonia, T. nataschae from the French sub‐Antarctic island Kerguelen, T. spinigerum from New Caledonia and T. watsoni from the Australian East Coast and New Caledonia. T. tori and T. galapagoensis, both formerly enclosed in T. setigerum, are considered new species, while T. australis also belongs to the same species group. Proxenetes denhartogi is transferred to Trigonostomum. Based on a comparison of old and new material, T. marki is synonymized with T. penicillatum, while T. prytherchi and T. divae are regarded as junior synonyms of T. lilliei; T. intermedium and T. quadrifolium are considered synonyms of T. coronatum. Three species are considered species inquirendae: T. brunchorsti, T. piriforme and Marinellia lingulifera. Similarities and differences of the 17 valid species are discussed and summarized in an identification key. © 2004 The Linnean Society of London, Zoological Journal of the Linnean Society, 2004, 141, 271–296.
Seven species of eukalyptorhynch flatworms from the Galapagos Islands are reported. Six of them belong to the taxon Koinocystididae Meixner, 1924, three of which are new to science. Two of these new species can be attributed to the genus Itaipusa Marcus, 1949 based on the construction of the prostate vesicle and the general structure of the female system. Itaipusa biglandula n. sp. is characterised by a very short, muscular, unarmed penis papilla, whereas I. renei n. sp. is characterised by the presence of a cirrus armed with minute scales, and two large, blunt hooks in the male atrium. The third new species cannot be placed in any existing taxon and therefore a new genus is erected: Galapagetula annikae n. gen. n. sp.. It is characterised by a straight and rather long cirrus, armed with small spines, and a clearly bipartite bursa in the female system. Additional morphological information is given for the three known species of Koinocystididae: I. divae Marcus, 1949; I. variodentata (Karling, Mack-Fira & Dörjes, 1972) Karling, 1978 and Utelga heinckei (Attems, 1897) Karling, 1954. For I. divae a new locality from Curaçao is also mentioned. The seventh species is a species of Gnathorhynchidae: Prognathorhynchus eurytuba Ax & Armonies, 1987, for which new morphological information on the organisation of the genital system is given.
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