A systematic review of the so-called cosmopolitan polydorid Polydora hoplura Claparede, 1869 (Polychaeta: Spionidae) on the South African coast.

[摘要] ENGLISH ABSTRACT: Introduction: Polydora hoplura is considered a cosmopolitan or alien species on the SouthAfrican coast and is an important pest affecting farmed abalone and oysters in the region. Thefirst description of P. hoplura by Day (1954) on the South African coast is notcomprehensive, and the documentation provides no relevant species-specific morphologicalinformation. Regional sampling conducted for the present study revealed that P. hopluravaried intraspecifically and consisted of at least four distinct morphotypes that maypotentially represent different species that may warrant redescription. By combiningtraditional taxonomic methods with molecular techniques, the following questions wereaddressed: 1) Do the morphotypes of P. hoplura represent a single species on the SouthAfrican coast? and 2) Are the South African representatives of P. hoplura conspecific tothose collected globally? In addition, the study included a literature review with the aim toprovide a brief history of the species to assess its cosmopolitanism.Materials and methods: Newly sampled specimens used in the morphological observationswere compared with specimens from private collections and museum material. Traditionaltaxonomic characteristics were used to distinguish the four morphotypes, and these includedmorphological features, pigmentation patterns, aspects of reproduction and habitatpreference. A cluster analysis was performed to assess the validity of the morphotypes.Furthermore, these morphotypes were also tested for potential genetic differentiation usingboth mitochondrial (Cytochrome b) and nuclear (28S) gene fragments. To gain preliminary insights into the level of global geographic genetic variation, South African specimens usedin the molecular analysis were compared to a few specimens collected in New Zealand.Results: Genetic data obtained from mitochondrial DNA and nuclear DNA failed todifferentiate the four morphotypes, suggesting that P. hoplura represented a singlemorphologically polymorphic species on the South African coast.Morphology: Morphotypes 1–3 were recognised as adult forms of the species, whilemorphotype 4 represented the first record of a juvenile form of the species.Pigmentation patterns: Morphotype 1 was characterised by the presence of dark pigmentationin the anterior region and morphotypes 2 and 3 by the absence of pigmentation. Morphotype4 had distinct pigmentation that resembled that of late-stage larvae.Aspects of reproduction: P. hoplura is poecilogenous, producing both planktotrophic andadelphophagic larvae. Late-stage adelphophagic larvae are morphologically similar to larvaeat the same stage from a previous study conducted by Wilson (1928).Habitat preferences: The cluster analysis and genetic investigation both showed that thespecies was not strictly host specific since individuals collected from abalone, oysters,scallops and sand showed genetic 'panmixia'.Conclusions: Different P. hoplura morphotypes collected along the South African coastlinerepresent the same gene pool when compared at the molecular level. Furthermore, the SouthAfrican specimens are molecularly similar to specimens collected in New Zealand. Thecosmopolitanism of the species could not be fully assessed as specimens from the NorthernHemisphere, particularly from the type locality, were not included in the study. It isconcluded that the species has been introduced into South Africa, in accordance with aprevious study (Mead et al., 2011).

[发布机构] Stellenbosch University