The phylogenetic position of Neogosseidae (Gastrotricha: Chaetonotida) and the origin of planktonic Gastrotricha
- PDF / 1,136,282 Bytes
- 11 Pages / 595.276 x 790.866 pts Page_size
- 66 Downloads / 154 Views
ORIGINAL ARTICLE
The phylogenetic position of Neogosseidae (Gastrotricha: Chaetonotida) and the origin of planktonic Gastrotricha Tobias Kånneby 1 & M. Antonio Todaro 2
Received: 27 April 2015 / Accepted: 4 June 2015 # Gesellschaft für Biologische Systematik 2015
Abstract Planktonic forms of Gastrotricha have been known since the 1850s, despite the fact that they are rather uncommon and difficult to collect. They are characterized by a round sack-shaped body, an absence of furcal adhesive tubes, and a different distribution of the locomotory ciliation compared to epibenthic and periphytic gastrotrichs. Today, planktonic gastrotrichs are classified into the three taxa—Dasydytidae, Neogosseidae, and Undula—but their origin and whether they share a recent common ancestor remain largely unknown. A long-held view is that planktonic taxa are derived from benthic ancestors related to Chaetonotus (Zonochaeta), but the hypothesis has never been properly tested. Here, in order to elucidate the phylogeny and origin of planktonic Gastrotricha, we provide the first molecular data on the very rare genera Kijanebalola and Neogossea, both members of the family Neogosseidae. We use Bayesian and maximum likelihood phylogenetics to analyze sequences of 18S rDNA, 28S rDNA, and COI mtDNA spanning 71 taxa in total. We find high support for a common origin of planktonic gastrotrichs, with monophyly of both Dasydytidae and Neogosseidae. Planktonic forms have evolved from epibenthic or periphytic ancestors, and the closest extant clade comprises members of Chaetonotus (Zonochaeta) + Chaetonotus heteracanthus Remane, 1927. These results further imply that the motile spines and underlying muscle patterns that control them in
* Tobias Kånneby [email protected]; [email protected] M. Antonio Todaro [email protected] 1
Department of Zoology, Swedish Museum of Natural History, Box 50007, SE-104 05 Stockholm, Sweden
2
Department of Life Sciences, University of Modena and Reggio Emilia, via Campi 213/d, I-41100 Modena, Italy
species of Dasydytidae are adaptations to the planktonic environment that evolved independently of those in other species of Gastrotricha. Keywords Meiofauna . Freshwater . Planktonic . Phylogeny . Paucitubulatina
Introduction Gastrotricha is a small phylum of aquatic acoelomate animals with approximately 850 species (see Balsamo et al. 2009, 2013, 2014; Hummon and Todaro 2010; Kieneke and Schmidt-Rhaesa 2014; Todaro et al. 2014; and references therein). The group is a common component of the meiofauna and is hypothesized to act as an important link between the microbial loop and larger invertebrate predators (Balsamo and Todaro 2002). The phylum is divided into the two orders Chaetonotida and Macrodasyida. Chaetonotida, present in both freshwater and marine habitats, are generally tenpinshaped with adhesive tubes confined to the posterior end and with the cuticle generally sculptured into various arrangements of scales and spines. Macrodasyida, with few exceptions, are entirely marine and vermiform,
Data Loading...
