Journal of Conchology 43 (4), October 2019

ISSN 2755-3531


The discovery of a sinistral Obeliscinae (Eupulmonata, Subulininae) in Brazil, found in Amazon archaeological shell mounds of Rondonia

Luiz Ricardo L. Simone & Sthefane D’ávila

Abstract. Rectobelus levogyrus, a new species of subulinid, is described found in archaeological surveys in Amazon shell mounts (sambaquis) from Costa Marques, Rondônia, Brazil. It is the first sinistral subulinid species recorded in Brazil, and that is its main distinguishing character. A brief taxonomical treatment of the other congener species, R. rectus (Baker, 1927) (the type species, from Venezuela) and R. birabeni (Hylton Scott, 1946) (from Argentina) is included, with figures, as well as a discussion on the validity of the genus.

Key words. Rectobelus levogyrus n. sp., Subulinidae, Amazon Region, zooarchaeology, morphology, shellmounds

New taxon. Rectobelus levogyrus Simone & D’ávila

Date of publication. October 2019


A possible natural dispersal mechanism among juveniles of the bioinvader snail Melanoides tuberculata (Thiaridae: Gastropoda) by floatation

Shirley Reis de Oliveira, Elizabeth Neves, Eduardo Mariano, Riccardo Mugnai & Rodrigo Johnsson

Abstract. Native to Africa through to SE Asia the invasive freshwater gastropod Melanoides tuberculata (Müller, 1774) has successfully spread to the American continent, and is a strong competitor of native gastropods. Deliberately introduced into the West Indies to combat schistosomiasis in the late 1970s, it is now widespread throughout the Caribbean. Its range has expanded to cover Brazil, where it was first observed in the 1960s, and throughout South America. Preying on eggs of local limnic molluscs, its impact has been devastating, with M. tuberculata replacing native populations (Ladd & Rogowski, 2012; Vogler et al., 2012). Furthermore, M. tuberculata exhibits parthenogenesis, is long-lived and is assumed to demonstrate an efficient dispersal mechanism; all of these factors are beneficial to a bioinvader that can reach high densities. With the addition of a high tolerance to variable environmental conditions such as salinity, eutrophication and pollution it is a voracious competitor with non-native species. Dispersal mechanisms of this bioinvader are key to learn about the spread of invasive species. The hypothesis of Melanoides’ floating behaviour was studied in the laboratory for a better understanding of its dispersal techniques through major Brazilian hydrographic systems. During a period of six months, under controlled conditions, reproductive adults were observed, and juveniles were for the first time observed floating, and moving, below the water film using their foot as a surfboard, and the proboscis as a paddle. This data could be useful in future control methods.

Key words. Melanoides tuberculata, floating, dispersal mechanism, juveniles

Date of publication. October 2019


Reassessment of Gyraulus spp. (Gastropoda, Planorbidae) from the Middle Miocene of Nördlinger Ries, Germany

Michael W. Rasser & Rodrigo B. Salvador

Abstract. Several fossil species of Gyraulus (Gastropoda: Hygrophila: Planorbidae) are known from the Miocene of continental Europe. An unpublished doctoral thesis from Bolten (1977) brought to light some new records of species from the Middle Miocene of Nördlinger Ries in southern Germany: G. ludovici (Noulet, 1854), G. kleini Gottschick & Wenz, 1916 and G. oxystoma (Klein, 1846). As the latter is considered one of the last in a lineage of endemics from the supposedly contemporaneous Lake Steinheim (Steinheim am Albuch), this report caught our attention. Thus, we re-analysed Bolten’s original material, arguing here that his Gyraulus spp. were misidentified: all his specimens belong to another common (and morphologically variable) Early/Middle Miocene species: G. applanatus (Thomä, 1845). Finally, G. kleini is here synonymised with G. applanatus.

Key words. Gyraulus, Hygrophila, Lake Steinheim, pulmonates, Ries impact crater

Date of publication. October 2019


Terrestrial gastropods of the Maldives, all of which are invasive?

Edmund Gittenberger, Bastian T. Reijnen & Dick S. J. Groenenberg

Abstract. Renewed collecting of land snails on various islands of the Maldives resulted in 23 new species records for that archipelago and a reconfirmation of 7 of the 9 species that had been listed for the region over a century earlier. Next to incidental records of single shells, populations of several species were recorded. Many species are well-known as invasive. Four species that were considered endemic to Sri Lanka are now also known from the Maldives, next to 10 additional, more widespread species that are shared. Therefore, Sri Lanka is hypothesised to be the main source of the Maldivian terrestrial molluscan fauna. A Sitalinopsis species that is known from 10 islands, belonging to 7 atolls, is described as new to science. It might be endemic to the Maldives albeit unlikely because of sea level fluctuations and occasional tsunamis that may have eradicated the terrestrial flora and fauna of the archipelago more than once in the geological past, counteracting time-consuming allopatric speciation.

Key words. Land snails, new species, invasive species, Sitalinopsis, Maldives, biogeography

New taxon. Sitalinopsis maldivensis  Gittenberger, Reijnen & Groenenberg, 2019

Date of publication. October 2019


An investigation into nematodes encapsulated in shells of wild, farmed and museum specimens of Cornu aspersum and Helix pomatia

R.M. Cowlishaw, P. Andrus & R. Rae

Abstract. Nematodes are prolific and diverse parasites of gastropods that have evolved to use slugs and snails as definitive and intermediate hosts. Recently, several snail species have been shown to encapsulate and kill nematodes by encasing them in their shell under laboratory conditions. However, it is unknown how common this process is in wild populations. Also there has been little research on how the morphology and physiology of the shell may influence the successful identification of nematodes trapped in snails’ shells using molecular biology. We examined shells from several U.K. populations that consisted of wild Cornu aspersum from Formby and Littlebourne and farmed C. aspersum from Lurgan, as well as Helix pomatia from snail farms in France (Brumath and La Rivière Drugeon). We found nematodes present in shells collected from four out of five locations with the number of shells infected with nematodes ranging from 17% to 100%. Using previously described protocols we attempted to amplify nematode DNA from the shells with nematodes. Nematode DNA could be amplified from C. aspersum from Lurgan (as previously reported) but not from the other three snail populations. This could potentially be due to low starting numbers of nematodes in the shell and high calcium content prohibiting amplification of DNA. In a final experiment we discovered that museum collections of C. aspersum and H. pomatia had nematodes present in their shellsthat were over 100 years old. Taken together, these results show that C. aspersum and H. pomatia frequently trap and fix nematodes using their shell in wild and farm environments. However, in order for these nematodes to be identified successfully nematode infection load and calcium content should be considered.

Key words. Cornu aspersum, Helix pomatia, C. elegans, nematodes, shells

Date of publication. October 2019


The opisthosiphons of North Andros Island, Bahamas (Annulariidae)

G. Thomas Watters

Abstract. Five taxa of Opisthosiphon are reviewed from the North Island of Andros Island, Bahamas: O. alleni, O. nicholasi, O. millsi (all Bartsch, 1946), O. androsensis Pilsbry, 1930, and O. thesaurus new species. Opisthosiphon alleni, previously recorded from New Providence and Eleuthera, has only been found at the San Andros airport on Andros Island and probably was anthropogenically introduced. Opisthosiphon thesaurus new species is a troglodytic taxon endemic to Henry Morgan Cave at Morgan’s Bluff. The distribution of these snails on the island may be dictated by the degree of inundation by hurricane storm surges.

Key words. Annulariidae, Bahamas, systematics, Opisthosiphon

New taxon. Opisthosiphon thesaurus Watters, 2019


Arculus sykesii (Chaster, 1895) [Bivalvia, Lasaeidae], revisited with lectotype selection and new northern records from the Viking Bank

P. Graham Oliver, Harriet Wood & David McKay

Abstract. Lectotype designation is made for Lepton sykesii Chaster, 1895 from shells in the 
Chaster collection held by the National Museum of Wales. Arculus sykesii (Chaster, 1895) is re-described with particular attention to details of the hinge teeth and ligament. Previous confusions concerning orientation of the valves is resolved. Verified records indicate a distribution from the Western Mediterranean to the northern North Sea. Recently collected specimens from the Viking Bank are the most northerly records yet.

Key words. Lectotype, scanning electron microscope, bivalve hinge, distribution

Date of publication. October 2019


Sarajana Radoman, 1975 (Caenogastropoda: Truncatelloidea): premature invalidation of a genus

Sebastian Hofman, Artur Osikowski, Aleksandra Rysiewska, Jozef Grego, Peter Glöer, Dejan Dmitrović & Andrzej Falniowski

Abstract. Sarajana apfelbecki (Brancsik, 1888) was assigned by Radoman to the monotypic genus, closely related to Belgrandiella Wagner, 1927. Later the distinctness of the genus Sarajana was questioned, and S. apfelbecki classified within the genus Belgrandiella. Our study on Sarajana from five localities in Bosnia and Herzegovina including Vrelo Bosne (type locality of the Sarajana apfelbecki) confirms that the morphology of the characteristic penis, as well as the female reproductive organs, with an exception of the presence of small, vestigial proximal seminal receptacle, overlooked by Radoman contradict a close relationships with Belgrandiella. Two molecular markers: mitochondrial cytochrome c oxidase subunit I (COI) and nuclear histone 3 (H3) were used to infer phylogeny: Sarajana was placed within the Hydrobiidae, Sadlerianinae, but far from Belgrandiella, with Graecoarganiella Falniowski et Szarowska, 2011 as a sister taxon.

Key words. Female reproductive organs, penis, cytochrome c oxidase subunit I (COI), histone H3, molecular phylogeny

Date of publication. October 2019


First records of Zonitoides arboreus (Say, 1817) from the Canary Islands [Short Communication]

Bernhard Hausdorf

Date of publication. October 2019


Obituary — Andrzej Hubert Wiktor (February 4 1931–December 31 2018)

Robert A. D. Cameron & Adrian Norris

Date of publication. October 2019


Obituary — David Long 1937–2018

Keith Alexander, June Chatfield & Martin Willing

David Long: Sojourn in Australia, 1969–1972

Robert Burn

Date of publication. October 2019