First record of Polymerurus (Gastrotricha, Chaetonotida) from Australia with the description of a new species from Queensland and of cuticular ultrastructure in P. nodicaudus

Abstract

Abstract. Identification of specimens in the genus Polymerurus (Gastrotricha, Chaetonotida) is reported for the first time from Australia. The genus includes 3 species from a freshwater lake in southern Queensland. Two species, Polymerurus rhomboides and P. nodicaudus, are well‐known cosmopolitans: P. rhomboides is now known from every continent except Antarctica, and P. nodicaudus from all continents except Africa and Antarctica. An ultrastructural description of the cuticle in P. nodicaudus is provided and confirms earlier observations on the structure of spined scales in other species of Chaetonotida, suborder Paucitubulatina. The utility of cuticle ultrastructure is discussed in reference to the search for characters defining higher‐level taxa in the Paucitubulatina. A new species, P. andreae, also cohabits the Queensland lake and is distinguished by the following combination of characters: wide mouth ring; pharynx with terminal bulb; simple spineless scales on the dorsal, lateral, and ventrolateral body surfaces; and a column of ventral interciliary scales in rectangular, ovoid, and intermediate shapes.