ISSN 2755-3531
P. Graham Oliver & Jørgen Lützen
Abstract. For the first time we propose ectoparasitism, by piercing and fluid-feeding in the Bivalvia. Draculamya porobranchiata gen. et sp. nov. is described and the anatomy reveals a number of functional adaptations related to the feeding mode. Primary among these is a puncturing organ situated at the anterior end of the byssus groove. The ctenidia are reduced to a series of ciliated pores set ventrally within a suspensory membrane and the labial palps are not present, indicating that suspension feeding cannot take place. The alimentary tract is highly modified; the oesophageal musculature is in the form of a suction pump. The fore stomach is greatly expanded, lacking sorting ridges and is presumed to store large volumes of ingested fluid. The central cavity of the stomach is poorly defined with a small gastric shield and style sac while the openings to the digestive diverticula are wide. The ovary is situated in the mantle and foreign sperm are stored in paired ctenidial seminal receptacles. No males were found. There are left and right pericardia and their failure to fuse as in other bivalves prevent the development of a heart. Oxygenation of the blood probably occurs across the thin walls separating the mantle cavity and the proportionally very large blood sinuses. Comparisons are made with Kurtiella tumidula (= Mysella verrilli) the only other described galeommatoid with a suctorial habit.
Key words. Draculamya porobranchiata, Galeommatoidea, functional morphology, systematics, ectoparasitism, fluid-feeding, Kurtiella tumidula
Date of publication: March 2011
Four new Napaeus species (Gastropoda: Pulmonata: Enidae) from La Gomera (Canary Islands)
Yurena Yanes, Javier Martín, Jesús Santana, Geraldine A. Holyoak, David T. Holyoak, Miguel Artiles, Francisco Deniz, Maria R. Alonso & Miguel Ibáñez
Abstract. Four new species of Napaeus are described from La Gomera (Canary Islands), which is one of the smaller islands of the archipelago but has the highest number of Napaeus species. The four new species can all disguise the shell with a cover of lichens, soil, or both, to reduce predation. When the covering is made of hygroscopic lichen, it might function as a water or humidity reservoir as well as for camouflage.
Key words. Napaeus, taxonomy, species radiation, insular endemics, genital anatomy, shells, shell disguise
Date of publication: March 2011
The littoral Trochoidea (Mollusca: Gastropoda) of the Azores
Sérgio P. Ávila, José Pedro Borges & António M. de Frias Martins
Abstract. A revision of the Azorean littoral Trochoidea is conducted and a description of the shell, animal and radula is provided. The endemic Calliostoma lividum (Dautzenberg 1927), originally proposed as a variety of C. conulus, is herein elevated to specific status and re-described. Of the remaining littoral trochid species reported from the Azores, two are dubious records, two are endemic (Jujubinus pseudogravinae and Gibbula delgadensis) and one has a wide geographical distribution in the North Atlantic (Gibbula magus). A note on the Pleistocene fossil record from Santa Maria is added and the dispersal abilities of the littoral trochids are commented.
Date of publication: March 2011
J.A. Allen
Abstract. Four new cuspidariid species from the deep Atlantic are described. In addition, a listing is given of all other species of the family Cuspidariidae reported so far from the Atlantic.
Key words. Bivalvia, Cuspidaria, deep-water, Atlantic, new species, bibliography
Date of publication: March 2011
Katarzyna Zając & Tadeusz Zając
Abstract. Unio crassus, an endangered freshwater mussel species, inhabits streams with diversified physical structure, subject to frequent changes in channel morphology. It is usually regarded as a sedentary animal, although individual movement has been observed. The hypothesis that adults can use movement in order to actively select a microhabitat was tested in two experiments simulating dislodgement of mussels by a stream. In the first experiment, begun in 2004, individually tagged Unio crassus individuals were distributed in a regular pattern throughout a 17 m long riffle-pool reach of Cedron River (S Poland). The mussels changed their positions after displacement. The distances travelled differed significantly between parts of the channel: they covered longer distances in the pool (ca 2 m) than in the riffle (ca 0.6 m), with minimal movements on steep banks and dead water areas and large movements in shallows and deep areas. Individuals from shallow places were found to have moved to the steep bank of the pool, built of fine sediments, and to the area of dead water in the lee of boulders. The movements were not related to the water depth gradient: individuals moved to the steep bank even from the deepest parts of the pool, a finding experimentally confirmed with radio-tracked individuals. The second experiment was begun in 2008 in a smaller reach 5 m long. The mussels were put in the deepest part of the reach. Most of them climbed to a steep bank built of fine sediment with minimal flow, and some of them hid beneath the gravel armouring the fast-flowing part of the channel. It can be concluded that adult Unio crassus individuals can move to any place in a channel after being disturbed by natural or artificially created fluvial processes. Steep banks of the pool, built of fine sediments, represented the best place of refuge.
Key words. Unio crassus, mussel behaviour, river channel structure, fine sediments, spate, radiotelemetry
Date of publication: March 2011
Anna Sulikowska-Drozd
Abstract. Population dynamics of the hygrophilous, egg-retaining clausiliid Vestia gulo was studied in the Carpathians (Poland) over three years at four sites that differ in their temperature regime. Juveniles (2.5 whorls) hatched in late June and/or in July. At the highest located site (1150 m a.s.l.) juveniles reached 3.5–4 whorls in the first growing season, 5.5–7 in the second, and probably attained maturity in the third or fourth season of their life (shells with 8.3–10.1 whorls). At the intermediate site (759 m a.s.l.), snails reached 4.0–6.0 whorls in the first growing season, 7.4–9.4 in the second and completed growth with 9.0–11.25 whorls at the third growing season. At two lowest sites (both at 425 m a.s.l.) populations of Vestia gulo differed in the growth rate, consequently snails reached ultimate size in two or three seasons. In the fastest growing population in the first season juveniles grew to 5.5–8.4 whorls, then during the second growing season they reached the ultimate size (9.25–12.25 whorls). Marked adults lived at least four years. Copulations were observed in autumn; in winter, there was hardly any growth.
Key words. Life-history, longevity, growth rate, land snails, Clausiliidae
Date of publication: March 2011
Description of the genital structure of four Turkish orculids (Gastropoda: Pulmonata: Orculidae)
Barna Páll-Gergely
Abstract. The genital structure of three orculid species occurring in north-eastern Turkey (Schileykula Gittenberger 1983) and one Pagodulina species from Southern Turkey (Pagodulina pisidica Schütt 1993) is described here. The taxonomic position of Schileykulaaculeata Gittenberger & Menkhorst 1993, Schileykula attilae Páll-Gergely 2010 and Schileykula sigma Hausdorf 1996 are clarified based on genital-morphological data, and all of these species are shown to belong to the genus Schileykula. The areal distribution of Schileykula is indicated. Surprisingly, the richest area for Schileykula, in terms of numbers of species, lies within the northeastern part of the range of the genus.
Key words. Schileykula, Pagodulina, Orculidae, taxonomy, Turkey
Date of publication: March 2011
Three species of Parthenina (Chrysallidinae, Pyramidellidoidea) New to West Africa
Frøydis Lygre, Christoffer Schander, Jon Anders Kongsrud & Jens Otto Krakstad
Abstract. Three species of pyramidellid gastropods, Parthenina suturalis (Philippi 1844), Parthenina flexuosa (Monterosato 1874) and Parthenina feldi (Aartsen et al. 2000), are reported from off West Africa for the first time. This represents a considerable increase in distribution range for all species, and indicates that the pyramidellid fauna of West Africa is still incompletely known in spite of several studies published in recent years. The shell morphology of the three species are described.
Key words. Chrysallida, Heterostropha, distribution, Pyramidellidae, Pyramidellidomorpha, West Africa
Date of publication: March 2011
A live trapping method for the protected European slug, Geomalacus maculosus Allman 1843 (Arionidae) [Short Communication]
Rory J. McDonnell & Mike J. Gormally
Date of publication: March 2011
Kevin Brown
Date of publication: March 2011