Effects of fragmentation on genetic variation in populations of the terrestrial earthworm Drawida japonica Michaelsen, 1892 (Oligochaeta,Moniligastridae) in Shandong and Liaodong peninsulas,China

Earthworms are excellent indicators of landscape fragmentation due to their widespread distribution and poor dispersal abilities over water. Based on field studies conducted in the Shandong and Liaodong peninsulas and their associated islands during summer 2009, we analysed the genetic variation of Drawida japonica Michaelsen, 1892 (Oligochaeta, Moniligastridae) using DNA sequences of the 16S and 28S ribosomal genes in samples obtained from 13 localities, 12 of which were islands, one artificially connected to the mainland by man (Yangma SC). We identified 55 haplotypes among 79 samples, based on 1094 bp, including 47 unique haplotypes. The phylogenetic tree topologies showed two distinct clades. A multiple-apex Poisson distribution using a mismatch analysis of nucleotides was also detected. Results of a Tajima D neutral test were not significant (p > 0.05). Genetic divergence among populations was much larger than within populations. A positive relationship between genetic diversity and island area was revealed, but no significant correlation between genetic diversity and distance to the nearest larger landmass was found. These results indicate that the intraspecific genetic diversity of D. japonica has been influenced by geographic isolation (i.e. island habitat). Passive transport via anthropogenic activities or nonhuman vertebrates (birds or mammals) may also play a key role in dispersal.     

The peracarid epifauna associated with the ascidian Pyura chilensis (Molina, 1782) (Ascidiacea: Pyuridae)

Epifaunal peracarids inhabit a variety of biogenic substrata, including ascidians. Herein we examined the peracarid fauna living on the tunica of the sublittoral ascidian Pyura chilensis growing in offshore and nearshore conditions in Bahía San Vicente, Chile. From a total of 38 samples we collected 17 species of Amphipoda, five Isopoda and two Tanaidacea. The similarity between the sites was high (73.8%, Sorensen's index). Species diversity (H') was 2.8 and 2.6, evenness (J) was 0.7 and 0.6 at the offshore and nearshore site, respectively. Both species and individual number increased significantly with the size (volume) of the ascidian samples, and these relationships did not differ between the sites. Many species, in particular the most abundant ones, occurred at both sites, but some species were restricted either to the offshore (three species) or to the nearshore site (seven species). Amphipods and tanaids were the most abundant taxa at both sites. The peracarid fauna at both sites was dominated by suspension-feeding peracarids (>80% of the individuals), which utilize the ascidians primarily as shelter, feeding on allochthonous material, i.e. not originating from the ascidians. It is suggested that the high percentage of suspension-feeding species among the epifaunal peracarids is due to the fact that ascidians settle and grow at sites that provide optimal feeding conditions for these organisms.     

The colonial ascidian fauna of Fiordland,New Zealand,with a description of two new species

A total of 17 species from the families Styelidae, Polyclinidae, Polycitoridae, Pseudodistomidae, Ritterellidae and Didemnidae are described for the first time in collections from remote fiords with steep-sided walls, high rainfall and high tidal flow on the south-west coast of New Zealand. The Fiordland ascidian assemblages are composed of endemic species, species with trans-Tasman affinities, species found in southern New Zealand and species found New Zealand wide, some of which have global distributions. Two Australian native species, Diplosoma velatum Kott, 2001 and Didemnum jucundum Kott, 2001 from South Australia are new records to New Zealand and a further eight species remain undescribed. Two new colonial ascidians Aplidium coronum sp. nov. and Trididemnum shawi sp. nov. are described in this paper.

http://zoobank.org/urn:lsid:zoobank.org:pub:5ADC2C9D-28AC-4348-8B4D-F26-2A43DEA66