First records of Gastrotricha from South Africa, with description of a new species of Halichaetonotus (Chaetonotida, Chaetonotidae)

M Todaro,Renzo Perissinotto,Sarah Bownes,Matteo Dal Zotto

doi:10.3897/zookeys.142.2036

Abstract

During a survey of the biota of the St. Lucia Estuary in the iSimangaliso Wetland Park, South Africa, a number of Gastrotricha were found among samples of meiofauna. Fresh, marine sediment yielded several specimens belonging to a total of seven species. Of these, two are already known from other regions (i.e., Dactylopodola australiensis and Heteroxenotrichula squamosa), one is described as new to science (Halichaetonotus sanctaeluciae sp. n.), while the remaining four (Pseudostomella sp., Halichaetonotus sp.1, Halichaetonotus sp. 2, Xenotrichula sp.) require further collections and analysis, in order to establish the extent of their affiliation to species already described. General appearance, shape of hydrofoil scale and the occurrence of three long spines on the dorsal side make the new species most closely related to Halichaetonotus australis and Halichaetonotus marivagus. The key differences from these taxa and between Halichaetonotus sanctaeluciae sp. n. and Halichaetonotus aculifer are discussed.

Highlights

Marine Gastrotricha from Africa are poorly known
Two species were identified as known taxa (Dactylopodola australiensis and Heteroxenotrichula squamosa), one is described here as new to science (Halichaetonotus sanctaeluciae sp. n.), while for the remaining four taxa the data gathered so far are not sufficient to exclude their affiliation to species already described
This would allow the collection of sufficient material to complement the traditional morphological studies with more advanced techniques, such as molecular analysis and confocal microscopy

Summary

Introduction

Marine Gastrotricha from Africa are poorly known. The latter work includes records of marine gastrotrichs from the Mediterranean and Red Sea coasts of Egypt. Scattered records of species can be found for Tunisia (e.g., Westheide 1972; Todaro et al 2011) and Kenya Macrodasys africanus, described long ago from Namibia, is the only gastrotrich species known from southern Africa (Remane 1950). This study was initiated after several gastrotrich specimens were recovered from formalin-fixed samples collected during an ongoing investigation of the biodiversity and ecology of meiofauna inhabiting the St Lucia Estuary (KwaZulu-Natal, South Africa). As identification to species of soft-bodied meiofaunal taxa, like Gastrotricha, is best achieved when the taxonomic characteristics are observed on fresh specimens, the collection of a series of samples was undertaken for a dedicated in vivo analysis

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