INGEOSUR   20376
INSTITUTO GEOLOGICO DEL SUR
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Variabilidad morfológica en Mactra Linné en el Cuaternario bonaerense.
Autor/es:
AGUIRRE, M.L., PEREZ, S.I., FARINATI, E.A. Y CHARÓ, M.
Lugar:
La Plata
Reunión:
Congreso; IV Congreso Argentino de Cuaternario y Geomorfología, XII Congresso Da Asociacao Brasileira de Estudos Do Quaternario, II Reunión sobre el Cuaternario de América del Sur; 2009
Institución organizadora:
Asoc. Arg. de Cuaternario y Geomorfología, Univ. La Plata, Asoc. Brasilera de estudios del Cuaternario
Resumen:
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Seven
species of Mactra have been reported living in Argentina, five (patagonica d´Orb.; petiti d´Orb., isabelleana d´Orb.,
janeiroensis d´Orb., marplatensis d´Orb.) have fossil
records in Late Quaternary sediments and modern littoral in the Argentine and
Magellanean Malacological Provinces, mostly in marginal marine localities along
the Buenos Aires province. Mactra
isabelleana, the most constant and abundant in marine deposits at 24
Bonaerensian sites (mostly beach ridges, tidal flat and coastal lagoonal facies)
of Pleistocene and Holocene age, exhibits a wide morphological variation
including different quantities of extreme specimens assignable to the remaining
species reported (morphs), which were
originally described mainly on shell shape characters only. Geometric morphometric methods were applied to highly correlated
attributes which best define shell shape on numerous (1200) fossil and modern
shells of different morphs to improve an objective evaluation of intraspecific
and interespecific variation of M.
isabelleana and to objectively define hard part boundaries between the
Bonaerensian species. Relative Warps analysis (RW; i.e. Principal Component analysis) on coordinates of 16 landmarks and 25 semilandmarks along the inner outline on digital images of the
right valve shows a marked
superposition of species, differences between M. isabelleana and the remaining morphs were
not different.