New Chaetonotus (Wolterecka. Semovitus sp. nov. (Gastrotricha: Chaetonotida: Chaetonotidae) from a Palm House in Vienna (Austria)

Abstract

Gastrotricha is a monophyletic phylum of small invertebrates inhabiting any kind of aquatic and semi-aquatic environments. Currently, ca. 850 gastrotrich species have been described, although the species numbers are not evenly distributed among the families and genera. The family Chaetonotidae Gosse, 1864 (sensuLeasi & Todaro, 2008) is considered the most numerous and diverse, with the most abundant genus being ChaetonotusEhrenberg, 1830. This genus has more species grouped together than all of the remaining genera of this family. Nevertheless, when the subgenera division within Chaetonotus is analysed it is noticeable that the differences in species number are also very large among these groups. One of the smallest and rarest is the subgenus WoltereckaMola, 1932, which currently includes only three nominal species. The main characteristics of this subgenus are short, reduced hook-shaped adhesive tubes and long, rigid spines on dorsal or dorsolateral surfaces of the furcal base and furcal appendages. In this paper, a new representative of Wolterecka is described, namely Chaetonotus (W.) semovitussp. nov. This taxon was found in the Schonbrunn Palm House in Vienna (Austria) and is distinguished from the other Chaetonotus (Wolterecka) species mainly by the presence of three pairs of cephalic cilia, a seven-lobed head outline and scales with a concave posterior edge and diversified shape around the body. For this new species, detailed morphological and molecular analyses including 18S rRNA, ITS1–5.8S rRNA–ITS2, 28S rRNA and COI mtDNA are presented.