Topic
Theodoxus
About: Theodoxus is a research topic. Over the lifetime, 47 publications have been published within this topic receiving 545 citations.
Papers
TL;DR: The Quaternary, mainly freshwater sediments of the Lower Mesopotamian plain include a thin transgressive marine unit which extends inland some 250 km from the present coastline, the Hammar Formation, which is indicative of a restricted, low energy marine environment.
Abstract: The Quaternary, mainly freshwater sediments of the Lower Mesopotamian plain include a thin transgressive marine unit which extends inland some 250 km from the present coastline, the Hammar Formation. The identity and respective areal extent of continental and transgressive units are based mainly on their molluscan faunas. Those faunas reflect the several environments of the Middle Eastern biogeographic province: fluviatile, lacustrine, estuarine and lagoonal. The ecological requirements of the more common subfossil and modern species of the malacofauna were studied during a month of field reconnaissance.
The freshwater portion comprises only four bivalve species (Corbicula, Unio, Anodonta and Pseudodontopsis). The principal gastropods include Theodoxus (Neritaea), Melanopsis, Melanoides, Bellamya, Gyraulus, Lymnaea (Radix) spp. Corbicula characterizes both fluviatile channels and lacustrine environments; Melanopsis, Melanoides, Theodoxus and the Unionaceae prefer shallow, sparsely vegetated, freshwater lakes. The greatest diversity was seen in the slowly flowing water of the channels draining the marshes; small Planorbids are rarely abundant whereas viviparid and lymnaeids may accumulate near the margins of marshes due to floatation during floods.
The brackish water faunas are characterized by Neritina (Dostia), the potamid Cerithidea (Cerithideopsilla), and Stenothyra. The new combination Theora mesopotamica (Annandale, 1918) is introduced here as the exact equivalent of Abra cadabra Eames et Wilkins, 1957. The abundance of these species is indicative of a restricted, low energy marine environment, confirmed by great numbers of the foraminiferan Ammonia gr. beccarii and the ostracod Cyprideis gr. torosa.
Reworked Hammar Fm marine fossils, first recorded by the Annandale (1918) collection from a lacustrine deposit near Nasiriyah, have been observed in river, marsh and lake sediments too, usually in association with scarce foraminifera. The limited occurrence of these macrofossils (abundant in their life environment) indicates reworking.
83 citations
1 Jan 2004
TL;DR: In this paper, an extraordinarily well-preserved brackish to freshwater gastropod fauna of the Early Pannonian (Late Miocene) is described, and a total of 34 taxa are described; among these, Boistelia soceni is introduced as new species or new hybrid.
Abstract: Summary An extraordinarily well-preserved brackish to freshwater gastropod fauna of the Early Pannonian (Late Miocene) is described. The assemblage derives from the Austrian part of the Eisenstadt-Sopron Basin (sand pit "Zollhaus" close to St. Margarethen in Burgenland, Austria) and represents a typical assemblage of the Pannonian Zone C/D. Green to greyish fine sand, deposited below wavebase off the coast of Lake Pannon, yields high numbers of synchronous, allochthonous shells of melanopsids and scattered autochthonous congerias and cardiids (Lymnocardiinae). Along with inhabitants of the adjacent rivers, such as Tinnyea escheri vasarhelyii and Unio atavus, the melanopsids were shed from coastal biotas of Lake Pannon into the somewhat deeper environment. Most of the shells acted as shuttle for micro-gastropods and thus allowed a sediment-microfauna bypass from the now eroded coastal habitat to the preserved basinal environments. A total of 34 gastropod taxa are described; among these, Boistelia soceni is introduced as new species or new hybrid. For the first time, attention is directed especially to the protoconchs and early ontogeny of several characteristic Lake Pannon gastropods. These studies also shed light on the until now rather dubious systematic treatment of the characteristic Pannonian genus Orygoceras BRUSINA, 1882, which is demonstrated to be of planorbid origin. This also results in the clear separation of the European, Late Miocene, endemic genus Orygoceras from the North American hydrobiids erroneously affiliated with this genus. Rarely reported and until now insufficiently documented representatives of the genera Theodoxus, Neritina, Goniochilus, and Gyraulus are described. Additionally, the systematic status of the oversplit Melanopsis fossilis-group is discussed.
48 citations
TL;DR: These phylogenetic results imply that much of the current taxonomy is flawed, therefore, recommendations for revising the classification of Theodoxus species based on phylogenetic systematics are offered.
39 citations
TL;DR: In this paper, a taxonomic description of 18 gastropod and five bivalve species from an Upper Oligocene succes- sion cropping out near Otranto (southern Salento, Apulia, Italy).
Abstract: Eighteen gastropod and five bivalve species are taxonomically described from an Upper Oligocene succes- sion cropping out near Otranto (southern Salento, Apulia, Italy). Among these, Tectarius (Echininus) japigiae, Hydrobia dubuissoni hydruntina, Pseudamnicola messapica, Pseudamni- cola palmariggii and Stenothyrella salentina are new taxa. Nonmarine and lagoonal environments characterize almost the whole succession, as testified by species-poor assem- blages rich in specimens of freshwater and oligo- to meso- haline prosobranchs, such as Neritinidae, Hydrobiidae, Stenothyridae, Thiaridae, Potamididae, Batillariidae, pulmo- nates, including Planorbidae and bivalves comprising Dreis- senidae and Cyrenidae. The genera Theodoxus, Hydrobia, Melanoides, Potamides, Terebralia, Batillaria, Granulolabium, Mytilopsis and Polymesoda alternately dominate. Littoral marine elements, such as Tectarius, Turritella, Barbatia, Anadara and Chama, are scattered present in the succession, but some prevail towards the top. The fauna is palaeobioge- ographically significant having strong affinities with those of the Oligo-Miocene basins of Aquitaine, Mainz, Bavaria, North Alpine Foreland, Vienna, Greece and Turkey. The analysed Otranto succession is assigned to the Chattian Galatone Formation of southernmost Apulia (Salento) based on lithological evidence and supported by the palaeonto- logical data.
33 citations
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Performance Metrics
| Year | Papers |
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| 2021 | 1 |
| 2020 | 3 |
| 2019 | 6 |
| 2017 | 3 |
| 2016 | 2 |
| 2015 | 2 |