First occurrence of the non-native bryozoan Schizoporella japonica Ortmann (1890) in Western Europe

Ryland JS, Rohan Holt, Jennifer Loxton, Mary Spencer Jones, Joanne Porter

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    Schizoporella japonica Ortmann was described from Japan but was subsequently introduced on Pacific oysters to the Pacific
    coast of North America, where it is now well established. In this paper we record it for the first time in European
    waters. The initial discovery was in a marina at Holyhead, North Wales, in July 2010 but S. japonica has since been observed
    abundantly in the Orkney Islands (from May 2011) and, subsequently, at other localities in northern Scotland. Introduction
    seems most likely to have been on an ocean-going vessel. The British material is here fully described and
    illustrated with SEMs and colour photographs; some unusual characters are discussed. Unlike other recently introduced
    bryozoans, S. japonica is a cold-water species and its breeding season in Britain extends through the winter. Extensive
    confusion between this and other species of Schizoporella on the west coast of Canada and the USA led us to make thorough
    morphometric comparisons between the species concerned (Schizoporella unicornis (Johnston in Wood),
    Schizoporella errata (Waters) and Schizoporella pseudoerrata Soule, Soule and Chaney). Zooid size in cheilostomate
    bryozoans is variable and often an unreliable character for species separation but shape (and therefore ratios between variables,
    which are independent of size) are often valuable: S. japonica zooids have a much greater length:width ratio than
    the other species. Density of frontal pseudopores provides a useful discriminatory character. Schizoporella unicornis, repeatedly
    reported in error from the Pacific coast of North America, does not occur there; it is a European species. Full
    comparisons are made between S. japonica and S. unicornis for European identification and between S. japonica, S. errata
    and S. pseudoerrata (which are also illustrated) for North American localities.
    Original languageEnglish
    Pages (from-to)481-502
    Number of pages22
    Publication statusPublished - 24 Mar 2014


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