Molecular phylogeny of Gastrotricha on the basis of a comparison of the 18S rRNA genes: Rejection of the hypothesis of a relationship between Gastrotricha and Nematoda

Петров, Н. Б.; Pegova, Anna; Manylov, Oleg; Vladychenskaya, N. S.; Mugue, N. S.; Aleshin, Vladimir V.

doi:10.1134/s0026893307030107

Cited by 21 publications

(23 citation statements)

References 29 publications

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“…Phylogenetic analysis of the Macrodasyida based on molecular traits (18S rDNA gene alone or in conjunction with the 28S rDNA and Cox 1 genes) have provided support for some of the traditional groupings based on morphological traits but have also unveiled surprising associations, e.g. congeneric species grouping with different families or morphologically disparate species grouping together (e.g., [24, 43, 44]).…”

Section: Discussionmentioning

confidence: 99%

An Integrated Morphological and Molecular Approach to the Description and Systematisation of a Novel Genus and Species of Macrodasyida (Gastrotricha)

2015

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BackgroundGastrotricha systematics is in a state of flux mainly due to the conflicts between cladistic studies base on molecular markers and the classical systematisation based on morphological traits. In sandy samples from Thailand, we found numerous macrodasyidan gastrotrichs belonging to an undescribed species of difficult taxonomic affiliation. The abundance and original nature of the specimens prompted us to undertake a deep survey of both morphological and molecular traits aiming at a reliable systematisation of the new taxon.Methodology/Principal FindingsUsing several microscopical techniques we investigated the external and internal anatomy, including the muscular and nervous systems of the new species. Additional specimens were used to obtain the 18S rRNA gene sequence; molecular data was analysed cladistically in conjunction with data from additional species belonging to the near complete Macrodasyida taxonomic spectrum. Specimens are vermiform, up to 806 μm in total length, and show a well-defined head equipped with peculiar leaf-like sensorial organs and a single-lobed posterior end. The adhesive apparatus includes anterior, ventrolateral, dorsal and posterior tubes. Pharynx is about 1/4 of the total length and shows pores at its posterior 3/4. Adult specimens exhibit maturing eggs and a bulky, muscular caudal organ, but do not show sperm nor the frontal organ. Musculature and nervous system organisation resemble the usual macrodasyidan plan; however, the somatic circular muscles of the intestinal region surround all other muscular components and a third FMRFamide-IR commissure ventral to the pharyngo-intestinal junction appear to be an autoapomorphic traits of the new species.Conclusions/SignificanceWhile the anatomical characteristics of the Asian specimens appear so unique to grant the establishment of a new taxon, for which the name Thaidasys tongiorgii gen. et sp. nov. is proposed, the result of phylogenetic analyses based on the 18S rRNA gene unites the new genus with the family Macrodasyidae.

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Section: Discussionmentioning

confidence: 99%

An Integrated Morphological and Molecular Approach to the Description and Systematisation of a Novel Genus and Species of Macrodasyida (Gastrotricha)

2015

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“…However, according to some analyses, they share this putative basal position with others such as Xenodasys and Acanthodasys (Todaro et al 2003: ML analysis) or with Paradasys, Cephalodasys, Urodasys, and Neodasys in a common clade (e.g., Todaro et al 2006a). Exceptions from a basal position of Dactylopodolidae provide the studies of Petrov et al (2007) and Kieneke et al (2008a). According to nucleotide sequence data of the 18S rRNA gene, Cephalodasys is the most basal lineage within Macrodasyida; however, no sequence of a dactylopodolid species was included (Petrov et al 2007).…”

Section: Phylogenymentioning

confidence: 99%

“…1.53 E). More recent cladistic analyses based on partial 18S rRNA gene sequences comprise a more satisfying taxon sampling among the gastrotrich genera , 2006a, Petrov et al 2007, Paps & Riutort 2012. More recent cladistic analyses based on partial 18S rRNA gene sequences comprise a more satisfying taxon sampling among the gastrotrich genera , 2006a, Petrov et al 2007, Paps & Riutort 2012.…”

Section: Phylogenymentioning

confidence: 99%

“…Another cladistic analysis of 135 phenotypic characters often used for taxonomy of Gastrotricha (e.g., number and arrangement of adhesive tubes, length/ width ratios, cuticular differentiations, shape of "head", trunk, and "tail", sensory appendages) provides a slightly different phylogeny for the internal relationships than the hitherto proposed scenarios. Besides Musellifer (Muselliferidae), the monophyletic family Xenotrichulidae (genera Draculiciteria, Xenotrichula, and Heteroxenotrichula) is also resolved to occupy a basal position within Paucitubulatina , Petrov et al 2007, sometimes as the result of the second speciation event after the first split that leads to Musellifer/Muselliferidae (Hochberg & Litvaits 2000, Todaro et al 2006a. 1.53 H).…”

Section: Phylogenymentioning

confidence: 99%

See 1 more Smart Citation

1. Gastrotricha

Kieneke¹,

Schmidt‐Rhaesa²

2014

Gastrotricha and Gnathifera

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“…Ruppert [23] states that the possibility of polyphyly is remote and gives the following apomorphies for a monophyletic Thaumastodermatidae: (i) complex cuticle, (ii) structure of the pharynx, (iii) lack of circular muscles in the lateral body regions, (iv) internal connection of vas deferens or vas deferentia to the caudal organ, and (v) multiciliated epidermal cells. Molecular studies are concordant with morphology and the group has been found monophyletic based on 18S rDNA by Todaro et al [11] and Petrov et al [21]. The only other investigation where some of the internal relationships within the family were studied is Todaro et al [11], which found high support for the monophyly of Diplodasyinae and Thaumastodermatinae.…”

Section: Discussionmentioning

confidence: 58%

Phylogeny of Thaumastodermatidae (Gastrotricha: Macrodasyida) Inferred from Nuclear and Mitochondrial Sequence Data

et al. 2011

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BackgroundPhylogenetic relationships within Gastrotricha are poorly known. Attempts to shed light on this subject using morphological traits have led to hypotheses lacking satisfactory statistical support; it seemed therefore that a different approach was needed.Methodology/Principal FindingsIn this paper we attempt to elucidate the relationships within the taxonomically vast family Thaumastodermatidae (Macrodasyida) using molecular sequence data. The study includes representatives of all the extant genera of the family and for the first time uses a multi-gene approach to infer evolutionary liaisons within Gastrotricha. The final data set comprises sequences of three genes (18S, 28S rDNA and COI mtDNA) from 41 species, including 29 thaumastodermatids, 11 non-thaumastodermatid macrodasyidans and a single chaetonotidan. Molecular data was analyzed as a combined set of 3 genes and as individual genes, using Bayesian and maximum likelihood approaches. Two different outgroups were used: Xenotrichula intermedia (Chaetonotida) and members of the putative basal Dactylopodola (Macrodasyida). Thaumastodermatidae and all other sampled macrodasyidan families were found monophyletic except for Cephalodasyidae. Within Thaumastodermatidae Diplodasyinae and Thaumastodermatinae are monophyletic and so are most genera. Oregodasys turns out to be the most basal group within Thaumastodermatinae in analyses of the concatenated data set as well as in analyses of the nuclear genes. Thaumastoderma appears as the sister taxon to the remaining species. Surprisingly, Tetranchyroderma is non-monophyletic in our analyses as one group of species clusters with Ptychostomella while another appears as the sister group of Pseudostomella.Conclusions/SignificanceResults in general agree with the current classification; however, a revision of the more derived thaumastodermatid taxa seems necessary. We also found that the ostensible COI sequences from several species do not conform to the general invertebrate or any other published mitochondrial genetic code; they may be mitochondrially derived nuclear genes (numts), or one or more modifications of the mitochondrial genetic code within Gastrotricha.

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Molecular phylogeny of Gastrotricha on the basis of a comparison of the 18S rRNA genes: Rejection of the hypothesis of a relationship between Gastrotricha and Nematoda

Cited by 21 publications

References 29 publications

An Integrated Morphological and Molecular Approach to the Description and Systematisation of a Novel Genus and Species of Macrodasyida (Gastrotricha)

An Integrated Morphological and Molecular Approach to the Description and Systematisation of a Novel Genus and Species of Macrodasyida (Gastrotricha)

1. Gastrotricha

Phylogeny of Thaumastodermatidae (Gastrotricha: Macrodasyida) Inferred from Nuclear and Mitochondrial Sequence Data

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