Holocene

The Holocene occurrence of the giant freshwater pearl mussel Pseudunio auricularius (Spengler, 1793) (Bivalvia: Margaritiferidae) in Belgium and the Netherlands

Authors: Wim J. Kuijper, Sofie Debruyne, Jean Pierre Parent
Basteria, 89 (2): 232-239Published:

Abstract

In recent decades, shells of the giant freshwater pearl mussel (Pseudunio auricularius) have been found in Holocene deposits in Belgium and the Netherlands. We give an overview of these observations, including previously published and new finds, and briefly outline the history of the occurrence of this rare and endangered species in Europe.

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Download articleArtikel The Holocene occurrence of the giant freshwater pearl mussel <em>Pseudunio</em> <em>auricularius</em> (Spengler, 1793) (Bivalvia: Margaritiferidae) in Belgium and the Netherlands

The genus Zootecus (Stylommatophora: Achatinidae: Subulininae) on the Eastern Atlantic islands, and the fairy tale of Z. insularis being a living fossil

Authors: Klaus Groh, Marco T. Neiber
Basteria, 89 (2): 240- 253Published:

Abstract

The genus Zootecus Westerlund, 1887 has a wide distribution range that stretches from Myanmar in the east over Sri Lanka, India, Pakistan, Iran, the Arabian Peninsula and North Africa to the Senegal and the Cape Verde Islands in the west. From the islands in the Eastern Atlantic Ocean, extant populations have only been reported from the Cape Verde Islands, where members of the genus are also known from Holocene deposits. Early Pliocene fossils of Zootecus have also been found in Lanzarote (Canary Islands). Until today, the name Zootecus insularis (Ehrenberg, 1831) has been used for specimens of the genus’ whole African and Asian distribution range, for extant specimens from all the Cape Verde Islands, as well as for the Early Pliocene fossils from Lanzarote. Many authors also referred to extant populations of Zootecus from the Cape Verde Islands under the species-group name Pupa subdiaphana P. P. King, 1832 – either as a distinct species, or as a subspecies or variety of Z. insularis. Here we accept Z. subdiaphanus as a distinct extant species and describe two additional species of Zootecus as new to science, Z. andreasi spec. nov. from Holocene deposits of São Vicente (Cape Verde Islands) and Z. christinaeamatae spec. nov. from Pliocene deposits of Lanzarote (Canary Islands). Buliminus couffoni Germain, 1910 from the Pleistocene of Mauretania is accepted as a valid species of Zootecus (comb. nov.). We show that the nominal taxon Z. insularis caucasicus Steklov, 1966 does not belong to Zootecus, but should better be regarded as a distinct species (stat. nov.) in the newly proposed genus Parzootecus gen. nov. of the family Enidae (comb. nov.). Also a “?Zootecus sp.” from the Palaeocene of the Oman and an unnamed species from the Neogene of Abu Dhabi are referred to the family Enidae instead of the family Achatinidae, Subulininae. Finally, arguments are presented that cast great doubts on the status of Z. insularis as representing a so-called living fossil. For the genus Chilogymnus Ehrenberg, 1831, we here select Helix aspersa O. F. Müller, 1774 as type species to protect the well-known name Zootecus. Consequently, Chilogymnus Ehrenberg, 1831 becomes a junior synonym of Cornu Born, 1778.

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Download articleArtikel The genus <em>Zootecus</em> (Stylommatophora: Achatinidae: Subulininae) on the Eastern Atlantic islands, and the fairy tale of <em>Z</em>. <em>insularis</em> being a living fossil

An early Holocene Rhine river fauna (Lent, Gelderland, The Netherlands) with Pseudunio auricularius (Spengler, 1793)

Authors: Wim J. Kuijper, Werner J.M. Peters, Martin C. Cadée, Frank P. Wesselingh
Basteria, 88 (2): 164-172Published:

Abstract

Baseline fluviatile mollusk communities are often poorly known, hampering their application in conservation purposes. Fossil/ancient faunas can become available through ex-situ dredged material. Continued collection and documentation effort is known to provide useful insights into past communities even though their ex-situ collecting introduces bias. A very rich dredged fauna from a sand extraction near Lent (prov. Gelderland, The Netherlands) provided the opportunity to reconstruct a Holocene Rhine fauna allowing us to address the question what a natural (pre-industrial) Rhine community may have looked like. The newly reported fauna consists of common palearctic species. The dominant fluviatile component consists mostly of species adapted to flowing water, such as unionids, large sphaeriid bivalves, and valvatid and neritid snails. It includes common Unio crassus (extinct 1968?) in the Netherlands, and also yields the critically endangered river pearl mussel Pseudunio auricularius also extinct in the Netherlands, possibly since the Roman period. A terrestrial component represents possibly riparian conditions.
Radiocarbon dating indicates an Early Holocene (Boreal) age for one valve of the pearl mussels, another river pearl mussel delivered an infinite age. Reworked Cenozoic fossils confirm a Rhine provenance. The newly reported fauna, even though of an ex-situ setting, gives good insights into a Holocene fluviatile baseline fauna. Today the Rhine faunas have been drastically modified by pollution and invasions of alien species.

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Download articleArtikel An early Holocene Rhine river fauna (Lent, Gelderland, The Netherlands) with <em>Pseudunio</em> <em>auricularius</em> (Spengler, 1793)

Distribution and ecology of Zootecus insularis (Ehrenberg, 1831) (Gastropoda, Pulmonata, Achatinidae, Subulininae) and its value as a palaeoenvironmental indicator species

Authors: Alberto Girod, Dael Sassoon
Basteria, 86 (2): 120-152Published:

Abstract

Zootecus insularis is a land snail usually confined to arid and semidesert environments. However, studies from the Arabian Peninsula and Pakistan have reported that this spe­cies have also lived in mesic habitats such as gardens, palm plantations, and other irrigated places. A likely reason for this contradiction is that Z. insularis is highly adaptable and therefore able to survive in semi-arid environments as well as more mesic microhabitats. Most of the mesic micro­habitats where Z. insularis has been found are of anthropic origin and, therefore, related to modern, often present-day ecology. We present an in-depth, comprehensive review of both ancient and modern occurrences of Z. insularis based on 19th and 20th century contributions of geographers, zoolo­gists, botanists, and archaeologists, and we investigate this species palaeoenvironment. Comparisons made between finds of Z. insularis, floral and faunal remains, and palaeoen­vironmental records show that this species had responded to periods of climatic variability in Asia and Africa during the Pleistocene and Holocene. Overall, our review contrib­utes to the understanding of the distribution of Z. insularis through space and time, and its use as a palaeoenvironmen­tal indicator.

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Download articleArtikel Distribution and ecology of <em>Zootecus</em> <em>insularis</em> (Ehrenberg, 1831) (Gastropoda, Pulmonata, Achatinidae, Subulininae) and its value as a palaeoenvironmental indicator species