Giving taxonomic significance to morphological variability in the bivalve Ptychomya Agassiz

The taxonomic significance of the morphological variability present in the genus Ptychomya Agassiz has remained obscure due to inadequacy of the traditional qualitative approach to account for complex patterns of variation. In this work, we focus on solving the distinction between intra- and intersp...

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Detalles Bibliográficos
Autores principales: Milla Carmona, P.S., Lazo, D.G., Soto, I.M.
Formato: JOUR
Materias:
Argentina
Geometric morphometrics
Lower Cretaceous
Ptychomya
Taxonomy
bivalve
Cretaceous
geographical distribution
interspecific variation
intraspecific variation
morphology
morphometry
paleontology
taxonomy
Bivalvia
Acceso en línea:http://hdl.handle.net/20.500.12110/paper_00310239_v59_n1_p139_MillaCarmona
Aporte de:
Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires
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spelling todo:paper_00310239_v59_n1_p139_MillaCarmona2023-10-03T14:41:09Z Giving taxonomic significance to morphological variability in the bivalve Ptychomya Agassiz Milla Carmona, P.S. Lazo, D.G. Soto, I.M. Argentina Geometric morphometrics Lower Cretaceous Ptychomya Taxonomy bivalve Cretaceous geographical distribution interspecific variation intraspecific variation morphology morphometry paleontology taxonomy Argentina Bivalvia The taxonomic significance of the morphological variability present in the genus Ptychomya Agassiz has remained obscure due to inadequacy of the traditional qualitative approach to account for complex patterns of variation. In this work, we focus on solving the distinction between intra- and interspecific variability in Ptychomya from Hauterivian marine beds of the Neuquén Basin (west-central Argentina), a longstanding and unresolved palaeontological issue, using the quantitative framework provided by geometric morphometrics and multivariate statistics. The species Ptychomya koeneni Behrendsen and several subspecies had been recognized in the studied succession by former authors based on qualitative morphological descriptions. We tested two hypotheses: (1) that there exist morphological discontinuities between hypothesized species that mark their boundaries; and (2) that morphology follows a pattern of geographical variation, suitable for recognition of subspecies. We find two morphological groups in the studied sample, with a significant morphological gap between them, supporting the idea that there are at least two species in the studied succession, Ptychomya cf. koeneni and Ptychomya coihuicoensis Weaver. On the other hand, we found no correspondence between morphological and geographical distributions, leading to the conclusion that the named subspecies are invalid taxa. This study highlights the potential of this methodological approach for solving the taxonomy of this notorious genus of pandemic distribution during the Cretaceous. © The Palaeontological Association. Fil:Lazo, D.G. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Soto, I.M. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. JOUR info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/2.5/ar http://hdl.handle.net/20.500.12110/paper_00310239_v59_n1_p139_MillaCarmona
institution Universidad de Buenos Aires
institution_str I-28
repository_str R-134
collection Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA)
topic Argentina
Geometric morphometrics
Lower Cretaceous
Ptychomya
Taxonomy
bivalve
Cretaceous
geographical distribution
interspecific variation
intraspecific variation
morphology
morphometry
paleontology
taxonomy
Argentina
Bivalvia
spellingShingle Argentina
Geometric morphometrics
Lower Cretaceous
Ptychomya
Taxonomy
bivalve
Cretaceous
geographical distribution
interspecific variation
intraspecific variation
morphology
morphometry
paleontology
taxonomy
Argentina
Bivalvia
Milla Carmona, P.S.
Lazo, D.G.
Soto, I.M.
Giving taxonomic significance to morphological variability in the bivalve Ptychomya Agassiz
topic_facet Argentina
Geometric morphometrics
Lower Cretaceous
Ptychomya
Taxonomy
bivalve
Cretaceous
geographical distribution
interspecific variation
intraspecific variation
morphology
morphometry
paleontology
taxonomy
Argentina
Bivalvia
description The taxonomic significance of the morphological variability present in the genus Ptychomya Agassiz has remained obscure due to inadequacy of the traditional qualitative approach to account for complex patterns of variation. In this work, we focus on solving the distinction between intra- and interspecific variability in Ptychomya from Hauterivian marine beds of the Neuquén Basin (west-central Argentina), a longstanding and unresolved palaeontological issue, using the quantitative framework provided by geometric morphometrics and multivariate statistics. The species Ptychomya koeneni Behrendsen and several subspecies had been recognized in the studied succession by former authors based on qualitative morphological descriptions. We tested two hypotheses: (1) that there exist morphological discontinuities between hypothesized species that mark their boundaries; and (2) that morphology follows a pattern of geographical variation, suitable for recognition of subspecies. We find two morphological groups in the studied sample, with a significant morphological gap between them, supporting the idea that there are at least two species in the studied succession, Ptychomya cf. koeneni and Ptychomya coihuicoensis Weaver. On the other hand, we found no correspondence between morphological and geographical distributions, leading to the conclusion that the named subspecies are invalid taxa. This study highlights the potential of this methodological approach for solving the taxonomy of this notorious genus of pandemic distribution during the Cretaceous. © The Palaeontological Association.
format JOUR
author Milla Carmona, P.S.
Lazo, D.G.
Soto, I.M.
author_facet Milla Carmona, P.S.
Lazo, D.G.
Soto, I.M.
author_sort Milla Carmona, P.S.
title Giving taxonomic significance to morphological variability in the bivalve Ptychomya Agassiz
title_short Giving taxonomic significance to morphological variability in the bivalve Ptychomya Agassiz
title_full Giving taxonomic significance to morphological variability in the bivalve Ptychomya Agassiz
title_fullStr Giving taxonomic significance to morphological variability in the bivalve Ptychomya Agassiz
title_full_unstemmed Giving taxonomic significance to morphological variability in the bivalve Ptychomya Agassiz
title_sort giving taxonomic significance to morphological variability in the bivalve ptychomya agassiz
url http://hdl.handle.net/20.500.12110/paper_00310239_v59_n1_p139_MillaCarmona
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AT lazodg givingtaxonomicsignificancetomorphologicalvariabilityinthebivalveptychomyaagassiz
AT sotoim givingtaxonomicsignificancetomorphologicalvariabilityinthebivalveptychomyaagassiz
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