Novel symbiotic relationship between a spionid polychaete and Lingula (Brachiopoda: Lingulata: Lingulidae), with description of Polydora lingulicola sp. nov. (Annelida: Spionidae)

A new spionid species Polydora lingulicola sp. nov., a novel symbiont of Lingula anatina Lamarck, 1801 is described here based on materials collected from the Yatsushiro Sea and Ariake Sea, southern Japan. Polydora lingulicola sp. nov., morphologically closest to P. glycymerica Radashevsky, 1993 and P. vulgaris Mohammad, 1972, is distinct from latter two shell-boring species by its smaller size, long maximum caruncle length, non-boring lifestyle, presence of subspherical yellow chromatophores on chaetiger 5 (visible in living specimens), and larval morphology. The new species was observed to construct mud tubes on the surfaces of L. anatina shells, with the tube apertures located near the lateral inhalant pseudosiphon of the hosts, and utilizes the water currents created by the filter-feeding host for feeding suspended food particles. Polydora lingulicola sp. nov. represents the first polychaetous annelid reported to exhibit an obligate symbiotic relationship with a lingulid brachiopod. Epibiotic polychaetes previously reported as P. cornuta Bosc, 1802 to occur on L. anatina shells from Japan in 1902 may belong to P. lingulicola sp. nov. The possibility that the wild populations of P. lingulicola sp. nov. may be vulnerable to extinction because they only associate with L. anatina, wild populations of which are near threatened by habitat loss, coastal pollution, and fishing pressure.

Proceraea exoryxaesp. nov. (Annelida, Syllidae, Autolytinae), the first known polychaete miner tunneling into the tunic of an ascidian

While studying organisms living in association with the solitary tunicatePhallusia nigra(Ascidiacea, Ascidiidae) from a shallow fringing reef at Zeytouna Beach (Egyptian Red Sea), one of the collected ascidians showed peculiar perforations on its tunic. Once dissected, the perforations revealed to be the openings of a network of galleries excavated in the inner tunic (atrium) by at least six individuals of a polychaetous annelid. The worms belonged to the Autolytinae (Syllidae), a subfamily that is well known to include specialized predators and/or symbionts, mostly associated with cnidarians. The Red Sea worms are here described asProceraea exoryxaesp. nov., which are anatomically distinguished by the combination of simple chaetae only in anterior chaetigers, and a unique trepan with 33 teeth in one outer ring where one large tooth alternates with one medium-sized tricuspid tooth, and one inner ring with small teeth located just behind the large teeth. Male and female epitokes were found together with atokous individuals within galleries.Proceraea exoryxaesp. nov. constitutes the first known miner in the Autolytinae and the second species in this taxon known to live symbiotically with ascidians. The implications of finding this specialized parasite are discussed considering thatPhallusia nigrahas been introduced worldwide, in tropical and sub-tropical ecosystems, where it has the potential of becoming invasive.

First record of the polychaetous annelid Diopatra micrura Pires et al., 2010 in the Mediterranean Sea

Until now the only recognised species of the onuphid genus Diopatra in the Mediterranean Sea was D. neapolitana. This paper reports the presence of another species, D. micrura, in the western Mediterranean, occurring in shallow waters along the coasts of southeastern Spain.

Characterization of a Novel Spirochete Associated with the Hydrothermal Vent Polychaete Annelid, Alvinella pompejana

ABSTRACT A highly integrated, morphologically diverse bacterial community is associated with the dorsal surface of Alvinella pompejana, a polychaetous annelid that inhabits active high-temperature deep-sea hydrothermal vent sites along the East Pacific Rise (EPR). Analysis of a previously prepared bacterial 16S ribosomal DNA (rDNA) library identified a spirochete most closely related to an endosymbiont of the oligochete Olavius loisae. This spirochete phylotype (spirochete A) comprised only 2.2% of the 16S rDNA clone library but appeared to be much more dominant when the same sample was analyzed by denaturing gradient gel electrophoresis (DGGE) and the terminal restriction fragment length polymorphism procedure (12 to 18%). PCR amplification of the community with spirochete-specific primers used in conjunction with DGGE analysis identified two spirochete phylotypes. The first spirochete was identical to spirochete A but was present in only one A. pompejana specimen. The second spirochete (spirochete B) was 84.5% similar to spirochete A and, more interestingly, was present in the epibiont communities of all of theA. pompejana specimens sampled throughout the geographic range of the worm (13°N to 32°S along the EPR). The sequence variation of the spirochete B phylotype was less than 3% for the range of A. pompejana specimens tested, suggesting that a single spirochete species was present in the A. pompejanaepibiotic community. Additional analysis of the environments surrounding the worm revealed that spirochetes are a ubiquitous component of high-temperature vents and may play an important role in this unique ecosystem.

Space Occupation by the Polychaetous Annelid Perinereis Cultrifera: Influence of Substratum Heterogeneity and Intraspecific Interactions on Burrow Structure

Spatial analysis, laboratory experiments and field observations in the intertidal zone of La Ranee Estuary (northern coast of Brittany, France) of the infaunal polychaete Perinereis cultrifera indicate that the distribution and the abundance of this species appear to be related to the availability of cobbles. Individuals build U-shaped galleries with a surface gutter network protected by a cobble which acts as a roof. The study of spatio-temporal evolution of P. cultrifera burrows showed experimentally that density is important in space-sharing modalities within the sediment. Effects of increased density lead to modifications in the shape and size of the burrows. The absence of connections between burrows, as observed in ‘sandwich aquaria’ and in resin casts, suggest that the gallery is defended against intruders. The study of the distance between individuals in the laboratory did not reveal a regular distribution pattern. These results probably mean that the area around the burrow opening is not defended and, therefore, does not constitute a territory. Perinereis cultrifera is probably competing for burrow space while food may be shared. Territoriality is certainly the main factor involved in the organization and the spatial arrangements of individuals within a population.

Mechanisms of trace metal accumulation in the polychaete Neanthes arenaceodentata

The mechanisms of accumulation of zinc and cadmium by the marine polychaetous annelid Neanthes arenaceodentata (Moore) have been studied. Animals have been exposed to EDTA chelate buffered sea water containing 65Zn and 109Cd. The calculated free ion activities of the zinc and cadmium in the sea water were 10-8.13 M and 10-7.65 M, respectively. Uptake occurs from the free ionic pool of metal and EDTA and EDTAmetal complexes are largely excluded from the animal. In unfed animals, the metals accumulate linearly with time at a rate which decreases when the temperature is reduced but increases in the presence of metabolic inhibitors. Experiments using [14C]EDTA as an extracellular marker indicate that the observed increase in accumulation caused by the inhibitors is at least partially due to media entering extracellular anatomical compartments such as the coelom and lumen of the gut which are normally isolated from the seawater by cilia or sphincters.