Tag Archives: strophocheilidae

Fossil connections

Recently a review paper appeared by Hammouda et al. (2017), in which some links between northern Africa and South America are suggested. The abstract is as follows:

“Terrestrial gastropods occur in many North African localities in Eocene continental deposits. Here we analyse the faunal assemblage from the Hamada de Méridja Formation in southwestern Algeria, dated as Early to Middle Eocene on the basis of charophytes. The assem- blage consists of three closely related species that to date have been classified either in the extant Madagascan genus Leucotaenius v. Martens, 1860, or in the SW European Eocene genera Romanella Jodot, 1957 and Vicentinia Jodot, 1957. This is rejected for shell morphological and phylogeographical reasons, and a new classification as Maghrebiola gen. nov. is proposed. Maghrebiola is tentatively placed in the South American family Strophocheilidae, as species from the Early Eocene Itaboraí Basin of Brazil, currently placed in the genus Eoborus Klappenbach and Olazarri, 1970 in the family Strophocheilidae, superfamily Acavoidea, have a very similar shell habitus. This record possibly extends the known geographical range of the Strophocheilidae into the African continent during the Eocene. Immigration of this stock into North Africa during the Cretaceous via a still existing plate connection is assumed. An attribution of Maghrebiola to the African family Achatinidae is unlikely for shell morphological reasons despite certain habitus similarities, although the Priabonian genera Arabicolaria and Pacaudiella from Oman most likely belong into this family, and not to the Vidaliellidae as originally proposed. Possible causes for the very low diversity of the assemblage are mainly unfavourable living conditions, i.e. a relatively dry climate resulting in sparse vegetation and only occasional presence of water bodies, which may have had increased salinities, accounting for the lack of freshwater mollusks. The absence of any competing large gastropods may possibly have facilitated high intraspecific variability leading to sympatric occurrence of three closely related species, due to the animals occupying a wide range of available ecological niches. As the species discussed here have also been attributed to the genera Romanella and Vicentinia in the Vidaliellidae, we provide an appendix with annotated characterisations of most genera of the Vidaliellidae and list the nominal species assigned to them. This family is tentatively placed in the South American superfamily Orthalicoidea; its stock would have similarly immigrated from South America, but have successfully colonized mainly SW Europe, with only one Eocene species [Romanella kantarensis (Jodot, 1936)] recognized in Algeria”.

This paper presents a provoking view on the relations between northern Africa, soutwestern Europe and South America during the Eocene. Perhaps food for discussion among palaeontologists?

Reference:
Hammouda, S.A., Kadolsky, D., Adaci, M., Mebrouk, F., Bensalah, M., Mahboubi, M. & Tabuce, R., 2017. Taxonomic review of the ‘‘Bulimes’’, terrestrial gastropods from the continental Eocene of the Hamada de Méridja (northwestern Sahara, Algeria) (Mollusca: Stylommatophora: Strophocheilidae?), with a discussion of the genera of the family Vidaliellidae. – Paläontologische Zeitschrift, 91: 85-112.

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Did Neotropical snails occur in Africa and Europe?

Fossils allow us a peek into the past, and although a lot remains uncertain and sometimes highly speculative (no molecules but only shell morphology to start with), they offer sometimes challenging views on worlds that have gone.

What we now call the Neotropics possibly once had a wider extension, and a team of Algerian and European scientists have made a study of Algerian shells that possibly give a clue. Hammouda et al. (2017) present a review of Eocene “Bulimes” and reached interesting but still tentative results.

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schermafbeelding-2017-02-09-om-06-46-57

Their abstract reads “Terrestrial gastropods occur in many North African localities in Eocene continental deposits. Here we analyse the faunal assemblage from the Hamada de Meridja Formation in southwestern Algeria, dated as Early to Middle Eocene on the basis of charophytes. The assemblage consists of three closely related species that to date have been classied either in the extant Madagascan genus Leucotaenius v. Martens, 1860, or in the SW European Eocene genera Romanella Jodot, 1957 and Vicentinia Jodot, 1957. This is rejected for shell morphological and phylogeographical reasons, and a new classication as Maghrebiola gen. nov. is proposed. Maghrebiola is tentatively placed in the South American family Strophocheilidae, as species from the Early Eocene Itaboraı Basin of Brazil, currently placed in the genus Eoborus Klappenbach and Olazarri, 1970 in the family Strophocheilidae, superfamily Acavoidea, have a very similar shell habitus. This record possibly extends the known geographical range of the Strophocheilidae into the African continent during the Eocene. Immigration of this stock into North Africa during the Cretaceous via a still existing plate connection is assumed. An attribution of Maghrebiola to the African family Achatinidae is unlikely for shell morphological reasons despite certain habitus similarities, although the Priabonian genera Arabicolaria and Pacaudiella from Oman most likely belong into this family, and not to the Vidaliellidae as originally proposed. Possible causes for the very low diversity of the assemblage are mainly unfavourable living conditions, i.e. a relatively dry climate resulting in sparse vegetation and only occasional presence of water bodies, which may have had increased salinities, accounting for the lack of freshwater mollusks. The absence of any competing large gastropods may possibly have facilitated high intraspecic variability leading to sympatric occurrence of three closely related species, due to the animals occupying a wide range of available ecological niches. As the species discussed here have also been attributed to the genera Romanella and Vicentinia in the Vidaliellidae, we provide an appendix with annotated characterisations of most genera of the Vidaliellidae and list the nominal species assigned to them. This family is tentatively placed in the South American superfamily Orthalicoidea; its stock would have similarly immigrated from South America, but have successfully colonized mainly SW Europe, with only one Eocene species [Romanella kantarensis (Jodot, 1936)] recognized in Algeria”.

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schermafbeelding-2017-02-09-om-06-52-35

The most recent, total overview of fossil and Recent Gastropoda was by Zilch, who classified the genera Romanella and Vidaliella with others in the “?Familia Anadromidae” within the Bulimulacea [currently Orthalicoidea] (Zilch, 1960); these genera are now placed in a family on their own, but based on their morphology there might be a resemblance with the Megaspiridae (e.g. Thaumastus). The link between the Mediterranean area and South America is further shown in the presence of the Clausiliid Neniinae, which the authors use as one of their arguments for their grouping of Maghrebiola with the Strophocheilidae. All this is an interesting but not implausible hypothesis.

References:
Hammouda, S.A., Kadolsky, D., Adaci, M., Mebrouk, F., Bensalah, M., Mahbouhi, M. & Tabuce, R., 2017. Taxonomic review of the “Bulimes”, terrestrial gastropods from the continental Eocene of the Hamada de Méridja (northwestern Sahara, Algeria) (Mollusca: Stylommatophora: Strophocheilidae?), with a discussion of the genera of the family Vidaliellidae. — Paläontologische Zeitschrift, (advance online) doi:10.1007/s12542-016-0333-5
Zilch, A., 1960. Gastropoda 2. Euthyneura. In: Schindewolf, O. (ed.) Handbuch der Paläozoologie, 6 (3–4): 401–834. Berlin: Borntraeger.

 

New record for Mirinaba

A new locality has been recorded for the species Mirinaba jaussaudi (Morretes, 1937) from Paraná state in Brazil.

schermafbeelding-2017-01-23-om-07-41-15

This species is now known from different ecoregions.

Reference:
Birckolz, C.J. & Gernet, M.V., 2016. New record of Mirinaba jaussaudi (Gastropoda, Strophocheilidae) in Paraná state, southern Brazil, and rectification of a known locality. – Strombus 23(1-2): 1-5.

Snails from central Chile

The abstract of the new paper by Araya (2016) reads: “Among the terrestrial invertebrates, the molluscan species of central and northern Chile have been scarcely studied and here, for the first time, a record of the diversity of land snail species of Los Molles (32◦14′ S, 71◦31′ W), in the Valparaíso region, central Chile is reported. Four species were found: Chiliborus rosaceus (King & Broderip, 1831); Lilloiconcha lopezi Araya & Aliaga, 2015; Plectostylus chilensis (Lesson, 1830), and Plectostylus reflexus (Pfeiffer, 1842); all of them are ground dwelling snails, endemic, occurring in small geographical ranges or in fragmented populations along northern and central Chile; L. lopezi is an endemic species to Los Molles. The geographic distribution records of P. chilensis and P. reflexus are also extended and illustrations of the species and distribution records are presented. The areas around Los Molles harbor a comparatively high diversity of plants and invertebrates, and they should be considered in future conservation efforts”.

schermafbeelding-2016-12-27-om-10-19-02

Reference:
Araya, J.F., 2016. On some land snails (Mollusca: Gastropoda) of Los Molles, central Chile. – Revista Mexicana de Biodiversidad, 87:1365–1368.

A new Gonyostomus species

Simone just published another brief paper describing a new Brazilian species. “Gonyostomus elinae is a new species collected from the Caboclos region of São Paulo, Brazil, extending the distribution of the genus south to the cavern environment of the central Atlantic rainforest. The new species differs from the other three species in the genus in having a different colour pattern of the shell, a wider umbilicus, smoother sculpture, and a wider aperture having a straight inner lip. The species can be already classified as endangered”.

schermafbeelding-2016-10-11-om-07-09-53

Reference:
Simone, L.R.L., 2016. A new species of the genus Gonyostomus from Brazil (Gastropoda, Stylommatophora, Strophocheilidae). – Spixiana 39: 11–13.

New snails from Brazil, Edo. Tocantins

The Brazilian state of Tocantins is relatively less-known, partly due to being a split-off of Goiás state. Since its Cerrado domain has been poorly studied, a paper by Salvador et al. (2015) is a welcome addition to our knowledge.

A sample of land snails, mainly pulmonates, was recently collected in southeastern Tocantins state, Brazil, close to the border with Bahia state. The following species were found in the material, all of them are reported for the first time from Tocantins: Helicina schereri (Helicinidae); Solaropsis fairchildi and Solaropsis rosarium (Camaenidae); Anostoma rossiCyclodontina cf. gemellata and Cyclodontina sectilabris (Odontostomidae); Drymaeus poecilus and Naesiotus carlucioi (Bulimulidae); Streptaxis luetzelburgi (Streptaxidae); Megalobulimus conicus (Strophocheilidae); Beckianum cf. beckianum (Subulinidae). Additionally, Drymaeus dakryodes sp. nov. is formally described herein. The new records and species addressed here constitute important findings, helping to fill distributional gaps and improving the knowledge of the local molluscan fauna. This is an essential step for future conservation efforts.

Salvador etal 2015 f15-23

The new Drymaeus species was found at Taguatinga, 12º21’54”S 46º21’39”W, ~870m. The holotype (fig. 15-16) is MZSP 114874. The specimen of Beckianum beckianum is a sinistral shell, and other sinistral specimens have been reported from Central America.

Reference:
Salvador, R.B., Cavallari, D.C. & Simone, L.R.L., 2015. Taxonomical study on a sample of land snails from southeastern Tocantins State, Brazil, with description of a new species. – Journal of Conchology 42: 67-78.

Type specimens in Rio de Janeiro

Type catalogues are the ‘telephone dictionaries’ of taxonomy. It is very convenient to have all data for a museum collection together in one publication, especially if the the collection isn’t digitalised and data is spread over many publications.

Pimenta et al. (2014) just published such catalogue for the molluscan collection of the Museu Nacional in Rio de Janeiro (MNRJ). In total 518 type lots have been recognised, representing 247 Gastropoda taxa, 30 Bivalvia taxa, 3 Cephalopoda taxa and 5 Scaphopoda taxa. After a very brief introduction, all taxa are listed alphabetically by class and by species name; the family name is included between square brackets. Some type specimens have been figured as well. In an appendix the taxa are listed per family.

Pimenta 2014

Land snail families represented are (number of taxa between parentheses): Succineidae (2), Charopidae (1), Orthalicidae sensu lato (29), Strophocheilidae (3), Clausiliidae (2). Of the latter family two taxa are excluded as types in the main text. In some cases the family names in the list do not correspond to those presented in the appendix; especially those belonging to the Orthalicoidea are treated in a confusing way (e.g., taxa belonging to the same genus allocated seemingly at random to one of two families). The family arrangement presented is clearly not up-to-date and conflicting with recent insights.

Finally, it is clear that type material from several taxa has been exchanged or deposited in the MNRJ after the original paper had been published (e.g.  several Weyrauch taxa), or that incorrect catalogue numbers have been published in recent works. All these data makes this ‘telephone directory’ useful for future reference.

Reference:
Pimenta, A.D., Monteiro, J.C., Barbosa, A.F., Salgado, N.C. & Santos Coelho, A.C. dos (2014). Catalogue of the type specimens deposited in the Mollusca collection of the Museu Nacional / UFRJ, Rio de Janeiro, Brazil. — Zootaxa 3780: 51–107.