Patricia Quintas

Spatial distribution of soft-bottom molluscs in the Ensenada de San Simón (NW Spain)

Abstract Distribution and abundance of the molluscan fauna was studied in the intertidal and subtidal soft-bottoms of the Ensenada de San Simón (NW Spain). Depth, grain size, and total organic matter were the most important factors in determining distribution patterns of molluscs in this inlet. Three major malacological assemblages have been determined in the Ensenada de San Simón, two of them subdivided in two facies. In the intertidal area of the inlet, one facies (A1) was located in areas associated with seagrass meadows of Zostera spp. and was dominated by Hydrobia ulvae (Pennant, 1777) whereas the second facies (A2) had a high dominance of H. ulvae, Cerastoderma edule (Linnaeus, 1758), and Tapes decussatus (Linnaeus, 1758). An impoverished facies of this community was present in reduced, muddy bottoms (Group C). In the subtidal bottoms, one group (B1) was located in the central part of the inlet with H. ulvae, Rissoa labiosa (Montagu, 1803), Turboella radiata (Philippi, 1836), Parvicardium exiguum (Gmelin in Linnaeus, 1791), Loripes lacteus (Linnaeus, 1758), and Abra nitida (Müller, 1789) as characteristic species. A second facies (B2) was found in outer areas of the inlet, characterized by Thyasira flexuosa (Montagu, 1803), Mysella bidentata (Montagu, 1803), Abra alba (Wood, 1802), and Nucula nitidosa Winckworth, 1930.

Phyllidiidae (Opisthobranchia: Nudibranchia) from Papua New Guinea with the description of a new species of Phyllidiella

Species of phyllidiid nudibranchs from Papua New Guinea (and other Indo-Pacific regions) are redescribed in this paper. A new species, Phyllidiella backeljaui n. sp., is described and compared with other species of the genus. External characters and internal morphology of the species studied have been examined in detail and illustrated, some of them for the first time such as Phyllidiopsis pipeki. In addition, new locations for Phyllidiella hageni and Phyllidiella zeylanica are reported from Papua New Guinea.

Distribution patterns of molluscan fauna in seagrass beds in the Ensenada de O Grove (Galicia, north-western Spain)

The distribution and composition of molluscan assemblages of seagrass beds in the Ensenada de O Grove (north-western Spain), are described in this paper. The studied bottoms were mostly muddy and colonized predominantly by Zostera marina L., Z. noltei Hornemann, or by both species. Molluscan fauna was dominated by gastropods and bivalves, in terms of both species richness and abundance. A total of 7641 individuals belonging to 68 taxa was identified. The most abundant species were the gastropods Peringia ulvae, Retusa truncatula and Calyptraea chinensis and the bivalves Abra alba, Loripes lucinalis and Kurtiella bidentata . Cluster and multidimensional scaling analyses based on Bray–Curtis similarity coefficient showed two distinct faunal assemblages. Group A comprised intertidal sites colonized either by Z. noltei or by Z. marina and Z. noltei on muddy sand and sandy mud bottoms and subtidal sites exclusively colonized by Z. marina in the outer part of the inlet on muddy sand with the highest values of species richness and diversity. Group B consisted of sites characterized by low values of species diversity and a species composition typical of a ‘reduced Macoma community’. The sorting coefficient and the combination of gravel, sorting coefficient and carbonates content (BIOENV analyses) and the salinity of bottom water and depth (canonical correspondence analyses) were the most important abiotic variables in explaining the structure of the molluscan assemblage.

Pisione parapari n. sp., a New Pisionid from the North-East Atlantic (Polychaeta: Pisionidae)

Abstract Pisione parapari n. sp. is described from shallow waters off North-West Spain. This new species and P. Remota (Southern, 1914) are the only representatives of the genus and family reported from Iberian waters. P. Parapari is characterised by the presence of several (1–4) non-succesive male copulatory organs, and by having slightly elongated dorsal cirri in chaetiger 2, an undivided neuropodial lobe, parapodia provided with long-bladed compound chaetae, and smooth palps.