A note on some Eurotatoria from Panjab State,India

Among 35 eurotatorian species presently reported from Panjab State, India, ten species are new records to this region while eight are new records from N. W. India. A new synonym is proposed and biogeographical remarks are made.     

Rotifers from West Bengal. IV. Further contributions to the Eurotatoria

This paper deals with 25 eurotatorien species (spread over eleven families) collected from Calcutta and its environs (Lower Bengal). Of these, 18 species represent new records from this state while six of them are new records from India.     

Phylogenetic Relationships of Acanthocephala Based on Analysis of 18S Ribosomal RNA Gene Sequences

Acanthocephala (thorny-headed worms) is a phylum of endoparasites of vertebrates and arthropods, included among the most phylogenetically basal tripoblastic pseudocoelomates. The phylum is divided into three classes: Archiacanthocephala, Palaeacanthocephala, and Eoacanthocephala. These classes are distinguished by morphological characters such as location of lacunar canals, persistence of ligament sacs in females, number and type of cement glands in males, number and size of proboscis hooks, host taxonomy, and ecology. To understand better the phylogenetic relationships within Acanthocephala, and between Acanthocephala and Rotifera, we sequenced the nearly complete 18S rRNA genes of nine species from the three classes of Acanthocephala and four species of Rotifera from the classes Bdelloidea and Monogononta. Phylogenetic relationships were inferred by maximum-likelihood analyses of these new sequences and others previously determined. The analyses showed that Acanthocephala is the sister group to a clade including Eoacanthocephala and Palaeacanthocephala. Archiacanthocephala exhibited a slower rate of evolution at the nucleotide level, as evidenced by shorter branch lengths for the group. We found statistically significant support for the monophyly of Rotifera, represented in our analysis by species from the clade Eurotatoria, which includes the classes Bdelloidea and Monogononta. Eurotatoria also appears as the sister group to Acanthocephala. Received: 12 October 1999 / Accepted: 8 February 2000     

Bayesian and Maximum Likelihood Analyses of Rotifer–Acanthocephalan Relationships

Rotifera is composed of groups with unusual ultrastructural, physiological, and reproductive characters. Our ability to understand the evolution of these features is complicated by the fact that the phylogenetic relationships among the three traditional rotifer groups (Seisonidea, Monogononta, and Bdelloidea) and Acanthocephala remain unresolved. Here, I present maximum likelihood and Bayesian analyses of rotifer–acanthocephalan relationships using both the protein-coding gene hsp82 and a combined data set of hsp82 and ribosomal small subunit (SSU) DNA sequences, using nucleotide and codon based models of evolution. Statistical analysis of the phylogenetic support for any of the likely relationships among rotifer groups suggests that more than a combined hsp82 + SSU data set will be needed to resolve rotifer–acanthocephalan phylogeny with any degree of certainty.     

Broad taxonomic sampling of mitochondrial cytochrome c oxidase subunit I does not solve the relationships between Rotifera and Acanthocephala

The phylogenetic relationships within Syndermata (Acanthocephala + Rotifera) are still unresolved. Cladistic morphological analyses support monophyly of Rotifera and Eurotatoria (Bdelloidea + Monogononta), while molecular phylogenies of 18S, 28S, COI, hsp82 and EST propose different topologies, with at least six contrasting scenarios. All these phylogenies are characterized by poor taxon sampling; thus, our aim is to solve the relationships within Syndermata sampling as many sequences as possible from one single locus. We reconstructed phylogenetic relationship using more than 1000 sequences of COI. We performed Maximum Likelihood and Bayesian phylogenetic reconstructions on amino acid alignments, using either Gnathostomulida or Platyhelminthes as an outgroup, and then we performed SH tests to provide confidence on the best phylogenetic hypotheses. All four major clades (Acanthocephala, Bdelloidea, Monogononta and Seisonidea) are always highly supported. The basal relationship among the four clades is not consistently resolved by any of the phylogenetic reconstructions; nevertheless, there is a strong support for a clade of Acanthocephala + Bdelloidea from the SH tests, in agreement with other phylogenies from ribosomal genes and EST analyses.     

Contributions to the rotifer fauna of ORISSA,India

This paper deals with 36 species of monogonont rotifers (belonging to 10 eurotatorien families) collected from Sambalpur (Orissa State) in Eastern India. Of the reported taxa, 15 species have been added as new records to the previous list from this region while one species represents a new record from this country.     

Early contributions of molecular phylogenetics to understanding the evolution of Rotifera

The past decade has seen the application of DNA sequence data to phylogenetic investigations of Rotifera, both expanding and challenging our understanding of the evolution of the phylum. Evidence that Acanthocephala, long regarded as a separate but closely related phylum, is a highly derived class of Rotifera demonstrates the potential of molecular analyses to suggest relationships not obvious from morphological analysis. Phylogenies based on the sequence of the gene for the small ribosomal RNA suggest that rotifers and acanthocephalans are associated with Platyhelminthes and Gastrotricha, perhaps in a clade with Gnathostomula and Cycliophora; at present, this group lacks a clear morphological synapomorphy. A more complete resolution of the molecular phylogeny of Rotifera will require surveying multiple genes and several species from each clade under investigation.     

Rotifers from west Bengal III. Further studies on the Eurotatoria

This paper presents an account of 41 rotifer taxa (spread over 31 species) belonging to five eurotatorien families i.e., Brachionidae, Euchlanidae, Mytilinidae, Trichotridae and Colurellidae. Amongst these, 29 are new records from the North Eastern region of this subcontinent and seven are indicated as new records from India.