3 results
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2. Biogeography and diversification of the freshwater planarian Crenobia alpina sensu lato (Platyhelminthes, Tricladida): A synthetic review.
- Author
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Sluys, Ronald
- Subjects
PLATYHELMINTHES ,GLACIAL Epoch ,BIOGEOGRAPHY ,FRESH water ,INFORMATION resources - Abstract
Through an in-depth study of the literature, as well as some other sources of information, geographical distribution maps of the various taxa of the European freshwater planarian genus Crenobia (Platyhelminthes, Tricladida) are provided, which document their records and distributional ranges in a detail that was previously unavailable. The genus Crenobia ranges across Northern, Western, Southern, and Eastern Europe, including several islands in the Mediterranean region, but is absent from a major part of the Iberian Peninsula; it is distributed also in Turkey. The chromosome portrait of Crenobia is complex, as it exhibits chromosome numbers that are multiples of 7, such as 28, 35, 42, 56, and 63. Sexually reproducing populations are tetraploid or hexaploid, while asexually reproducing populations exhibit high chromosome numbers. All taxa of Crenobia are stenothermic, cold-loving species. Although historical biogeographic scenarios interpreting the taxonomic diversification of the genus as being the result of the vicissitudes of the Last Ice Age are still captivating, it may be the case that the genus already diversified 6-20 million years ago. The paper sketches in some detail the anatomy of the copulatory complex of the various taxa. Previously, it went unnoticed that in two of the taxa (Crenobia alpina and C. anophthalma) the two sperm ducts have different, asymmetrical trajectories. Further, it was largely undocumented that in several taxa the sperm ducts exhibit a pronounced recurvature, as well as a dorsal loop before entering the penis papilla. Neither did previous studies document that in C. montenigrina the mouth opening is not located at the most posterior end of the pharyngeal pocket, but has shifted anteriad for some distance. Polypharyngy is a stable, species-specific character, with C. montenigrina usually exhibiting 11-17 pharynges, while C. anophthalma has never more than three pharynges. Different views have been expressed on the taxonomic status of several geographic and anatomical forms of Crenobia. It is shown here that Crenobia comprises five, well-defined full species, viz., C. alpina , C. corsica , C. montenigrina , C. anophthalma , and C. bathycola. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
3. The Middle-to-Upper Paleolithic transition occupations from Cova Foradada (Calafell, NE Iberia).
- Author
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Morales, Juan I., Cebrià, Artur, Burguet-Coca, Aitor, Fernández-Marchena, Juan Luis, García-Argudo, Gala, Rodríguez-Hidalgo, Antonio, Soto, María, Talamo, Sahra, Tejero, José-Miguel, Vallverdú, Josep, and Fullola, Josep Maria
- Subjects
NEANDERTHALS ,SEQUENCE stratigraphy ,GEOLOGICAL time scales ,POPULATION ,EARTH sciences ,PALEOLITHIC Period - Abstract
The Middle-to-Upper Paleolithic transition in Europe covers the last millennia of Neanderthal life together with the appearance and expansion of Modern Human populations. Culturally, it is defined by the Late Middle Paleolithic succession, and by Early Upper Paleolithic complexes like the Châtelperronian (southwestern Europe), the Protoaurignacian, and the Early Aurignacian. Up to now, the southern boundary for the transition has been established as being situated between France and Iberia, in the Cantabrian façade and Pyrenees. According to this, the central and southern territories of Iberia are claimed to have been the refuge of the last Neanderthals for some additional millennia after they were replaced by anatomically Modern Humans on the rest of the continent. In this paper, we present the Middle-to-Upper Paleolithic transition sequence from Cova Foradada (Tarragona), a cave on the Catalan Mediterranean coastline. Archaeological research has documented a stratigraphic sequence containing a succession of very short-term occupations pertaining to the Châtelperronian, Early Aurignacian, and Gravettian. Cova Foradada therefore represents the southernmost Châtelperronian–Early Aurignacian sequence ever documented in Europe, significantly enlarging the territorial distribution of both cultures and providing an important geographical and chronological reference for understanding Neanderthal disappearance and the complete expansion of anatomically Modern Humans. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
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