Filling a gap in the phylogeny of flatworms: relationships within the Rhabdocoela (Platyhelminthes), inferred from 18S ribosomal DNA sequences

Abstract

. 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.

Diceratocephala boschmai (Platyhelminthes: Temnocephalida) from crayfish farms in Thailand: investigation of the topographic surface and analysis of 18S ribosomal DNA sequences

“…This result confirms the molecular point of view in which Temnocephalida is considered to be monophyletic within the Rhabdocoela, and it is in agreement with a report by Willems et al (2006), in which Rhabdocoela was monophyletic based on the 18S rDNA sequences of 62 rhabdocoels, including Temnocephala spp. Therefore, this result fills a gap, placing D. boschmai into the scheme of the phylogenetic relationships within the Rhabdocoela as classified by 18S rDNA sequences.…”

Comparative spermatology of selected polyclad flatworms (Platyhelminthes)

“…In the spermatozoa of Platyhelminthes, we also can distinguish characters that can be very useful for phylogenetic considerations at different taxonomic levels. In recent morphological and molecular phylogeny analyses of Platyhelminthes (Zamparo et al, 2001;Zrzawy, 2001;Baguñ à and Riutort, 2004;Petrov et al, 2004;Willems et al, 2006), sperm morphology always is considered a valuable character. According to Watson and Rohde (1995), homologous characters of sperm that are phylogenetically useful include the number of axonemes, their state (free or incorporated) and placement, split tips of flagella, the location and form of mitochondria, the nature of the nucleus, the presence, number, and types of dense bodies, the presence of peripheral microtubules, and the presence of small (25 nm in diameter) granules in the sperm shaft.…”

Report on the Polycystididae (Rhabdocoela, Kalyptorhynchia) from Australia, with the Description of Twelve New Species and Six New Genera

“…(Figs 12d, 14d) Synonymy: 'Stradorhynchus terminalis' in Willems et al (2006) Distribution: Coffs Harbour (New South Wales), Coffs creek, south bank, about 75 m west from the bridge, fine-grained sand and algae in a channel, 23 Jul. 2003 (type locality); same locality, about 100 m west from the bridge amongst mangroves on the north shore of the creek; sandy to silty sediment, 15 Jul.…”

“…(Figs 4, 6e) Synonymy: Arrawaria n. gen. in Littlewood et al (1999) Arrawaria Willems et al (2006) Distribution: Arrawarra (New South Wales), small shell-shaped brown algae from a tidal pool in the mid-eulittoral, 28 Aug. 1996 (type locality); same locality, various algae from several tidal pools near the marine station, 27 and 28 Aug. 1996 and 1 Nov. 1997. Sydney (New South Wales, Australia), various algae from Bondi Beach, 6 Oct.…”