Strategies for tube construction in Owenia caissara (Oweniidae, Annelida) from southern Brazil

On the Systematics and Biodiversity of the Palaeoannelida

“…Capillary chaetae show external structures under SEM like densely packed scales. Morphometric analyses of these scales have shown value for identification of species of Owenia (e.g., [163,164]), although some authors found the intra-and interspecific variation to overlap [77]. Neurochaetae come in the shape of dentate hooks with long shafts (i.e., uncini) provided with two distal teeth, homologous to the capitium of other annelids but lacking instead a true rostrum (Figure 14A,B, Figure 15A-C and Figure 16C,D) [57].…”

“…Teeth are generally arranged vertically (one on top of the other) in members of Myriochele and Myriowenia, and horizontally (teeth occurring side by side) in Owenia species [57]. Morphometric analyses with the aid of SEM have also been performed within members of Owenia in order to find distinct traits to separate species among this morphologically homogenous group [77,163,164]. Oweniids display a variability of pygidial shapes.…”

“…While the same characters are considered across the family due to the relative homogeneity in the oweniid body shape, the anterior end shows more variation among genera and is therefore more useful for species characterisation. However, for all members of Oweniidae, the use of a SEM is essential, and as mentioned before, very often morphometric analyses are needed for species discrimination [77,81,163,164]. Branching patterns of the head tentacles have also been shown to bear taxonomic information for some Owenia species [78].…”

“…The use of methyl blue stain and the different colouration body patterns in Owenia is being increasingly used (e.g., [71,164]) although its use as a taxonomic character in the characterisation of the species is not generally used in recent works (e.g., [74,78]). Iconography has also shown much variation across the literature through time (Figure 19), even showing evident differences in artistic quality.…”

“…Branchial tentacles and buccal lips are involved in tube building (e.g., [158][159][160]). It has been argued as to whether the materials utilised for the tube are preselected, and whether there is any preference for type and size of particles used [64,66,164] or whether the animal simply relies on any available material [67,68]. It appears that tube-building patterns depend on the species under consideration, development and the availability of materials.…”