Invasive Species Compendium

Detailed coverage of invasive species threatening livelihoods and the environment worldwide

Abstract

Two alien species of branchiobdellida (Annelida: Clitellata) new to the British Isles: a morphological and molecular study.

Abstract

Freshwater ecosystems are particularly vulnerable to the effects of alien species and decapod crustaceans, notably crayfish, are a principal threat. Although symbiotic fauna may influence the impact and dispersal of introduced species, this is often overlooked. Here we provide the first record of non-native ecto-symbiotic branchiobdellidan worms on invasive signal crayfish (Pacifastacus leniusculus Dana, 1852) in the British Isles. Using morphological and molecular techniques we identified and re-described two branchiobdellidan species new to the UK, Xironogiton victoriensis Gelder and Hall, 1990 and Cambarincola aff. okadai Yamaguchi, 1933, both of which were found at a single location in the Gavenny River, South Wales. The prevalence of X. victoriensis and C. aff. okadai was 75.34% and 71.23% respectively. Although the level of X. victoriensis and C. aff. okadai co-infection was high at 75.41% of all infected animals, the two species exhibited different micro-habitat preferences on the host with the former being found predominantly on the chelae and walking legs and the latter on the carapace and abdomen. For both branchiobdellidan species, worm burdens were positively correlated with crayfish size. The lack of branchiobdellidan records from signal crayfish in nearby water bodies, and the reports of native white clawed crayfish (Austropotamobius pallipes) in the Gavenny as recently as 2000, indicates that introduction of this worm infested population occurred relatively recently, despite stringent legislation banning the import and transportation of non-native crayfish into the UK.