Myzostoma fuscomaculatum (Myzostomida), a new myzostome species from False Bay, South Africa
A new myzostome species, described here as Myzostoma fuscomaculatum n. sp. was collected on Tropiometra carinata in False Bay (South Africa), during a survey of symbionts associated with comatulid crinoid species. M. fuscomaculatum n. sp. occurred only on T. carinata and not on the more common crinoid, Comanthus wahlbergi. It infested 61.7% of the 120 host specimens collected, of which 64.9% (48 specimens) hosted more than one individual (maximum of 32). M. fuscomaculatum n. sp. was always located on the host’s arms and pinnules and was cryptically coloured, closely matching the colour pattern of the host. This is the first record of myzostomes from the cool temperate waters of South Africa’s Atlantic coast. The new species is morphologically close to M. gopalai Subramaniam, 1938, collected on T. encrinus in Madras Harbour. M. fuscomaculatum n. sp. differs from M. gopalai in lacking marginal cirri at the adult stage, the presence of three pairs of digestive diverticula, by the position of its lateral organs and by the shape of the manubrium. Molecular phylogenetic analyses based on 18S and 16S rDNA placed M. fuscomaculatum n. sp. into a clade including Hypomyzostoma, Myzostoma and Mesomyzostoma species.
KeywordsMyzostomida Annelida Taxonomy South Africa Atlantic Ocean Phylogenetic analysis
We thank G. Jones and S. Albert for the first photograph of M. fuscomaculatum n. sp., and P. Southwood and G. Zsilavecz of the Southern Underwater Research Group (SURG) for their assistance in the collection of specimens. Many thanks are also expressed to R. Boshoff and the South African National Parks Marine Unit for diving assistance and the use of their boat. Thanks are due to M. Todesco and B. Joly for assistance in the sequencing and histological sections. The authors thank Mark J. Grygier for his courtesy in giving the authorization to publish some of his personal notes, and the two reviewers for helpful comments on the manuscript. The National Fund for Scientific Research, Belgium (FRFC) provided financial support for histological sections, SEM and molecular analyses. Tessa Hempson and Charles Griffiths were supported by a grant from the SEAChange Programme of the South African National Research Foundation. Déborah Lanterbecq was supported by a Postdoctoral Research Associate grant from the ‘Fonds de la recherche scientifique’ (FNRS).
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