Aequipecten tehuelchus madrynensis (Bavay, 1906)
BAVAY, A. 1906. Note au sujet de Pecten de la République Argentine et rectification de nomenclature. Journal de Conchyliologie, 54: 5-11. [p. 6, pl. 1, figs. 6-7]
1906 Pecten tehuelchus madrynensis Bavay, 1906
A. Bavay, 1906, plate 1.
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«Dans le Golfo nuevo (Territoire de Chubut), à Puerto Madryn, M. Lahille a observé une variété de P. tehuelchus à laquelle il donne le nom de var. Madryni (ou mieux madrynensis).
La taille, la forme générale de la coquille, la dépression des valves, le nombre des côtes, la forme et l'ornementation de celles-ci subissent des modifications qui donnent lieu à des variétés importantes et qu'il faut reconnaître pour se faire une idée exacte de cette espèce. La taille varie de trente à soixante-dix millimètres chez des individus vivants pour atteindre quatre-vingts à quatrevingt-quinze millimètres chez des individus fossiles; la forme est plus ou moins haute et la coquille, d'ordinaire peu renflée, peut devenir ventrue. L'épaisseur de la coquille oscille entre un tiers et un demi du plus grand diamètre. Le nombre des côtes varie de onze à vingt, il est généralement de seize dans le type. Il peut diminuer sans que la forme générale des côtes et leur ornementation se modifient, mais le plus souvent, la réduction dans le nombre de ces côles s'accompagne de changt;ments notables dans leur forme et dans leur sculpture. (...) Var. δ madrynensis Lahille in mss., Costae 11-14, validae rotundatae vel quadratae, latae, exornatae.» ARTHUR BAVAY, 1906
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«The non-commercial Flexopecten felipponei formed a monophyletic group with the two subspecies of Aequipecten tehuelchus. Waller (1991, 2006) concluded that Flexopecten s.s. would be related to Aequipecten and restricted to the Mediterranean and adjacent eastern Atlantic with a single ‘outlier’ species, F. felipponei, occurring in the western South Atlantic. Orensanz et al. (1991), on the examination of soft tissue and simultaneous hermaphroditism of numerous individuals with intermediate characters, proposed that ‘F.’ felipponei would be only a phenotypic variant of A. tehuelchus, a hypothesis supported by our results. We found that Flexopecten glaber is grouped together with Aequipecten opercularis within the Pectinidae, both being phylogenetically distant from F. felipponei. This result is in agreement with those of Canapa et al. (2000), but in contrast with the results of Waller (1991) who placed Flexopecten as a member of the Decatopecten group, distant from Aequipecten.
Our phylogenetic reconstruction suggests that the clade formed by the three morphotypes of the Tehuelche scallop distributed along the south-western Atlantic Ocean is more closely related to the genus Argopecten from the Eastern Pacific and North and Central-Western Atlantic than to the other members of the genus Aequipecten, including the type species of the genus, Aequipecten opercularis (Linnaeus 1758), a species distributed in the Norwegian and Mediterranean seas (Huber, 2010). Aequipecten tehuelchus was originally classified in Chlamys (d’Orbigny 1842) and considered a species of this genus until Waller (1991) and Del Río (1992) transferred it to Aequipecten, even though Aequipecten is primarily distributed to the North Atlantic. A more comprehensive phylogenetic reconstruction of the family Pectinidae (Alejandrino et al., 2011; but see also: Saavedra & Peña, 2006; Puslednik & Serb, 2008; Feng et al., 2011) showed that the monophyletic genus Chlamys, including the type species Chlamys islandica (O. F. Müller, 1776), is very distant to both genera Argopecten and Aequipecten. In our phylogeny, the Tehuelche scallop is located in a basal position within the clade formed by the species belonging to the genus Argopecten. Therefore, we recommend transfer of the species including the forms: A. t. tehuelchus, A. t. madrynensis and Flexopecten felipponei, to the genus Argopecten Monterosato, 1889.»
TROVANT, B., L. E. REAL, A. M. PARMA, J. M. ORENSANZ & N. G. BASSO. 2018. Evolutionary relationships of the Tehuelche scallop Aequipecten tehuelchus (Bivalvia: Pectinidae) from the south-western Atlantic. Journal of the Marine Biological Association of the United Kingdom, 2018: 1-9, figs. 1-3. [p. 6, 7]
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«Phenotype variation of the Tehuelche scallop. To the left: Flexopecten ‘felipponei’ of two different sizes; to the right at the top, Aequipecten tehuelchus
‘tehuelchus’ and below, Aequipecten tehuelchus ‘madrynensis’»; B. Trovant, L. E. Real, A. M. Parma, J. M. Orensanz & N. G. Basso, 2018, Evolutionary relationships of the Tehuelche scallop Aequipecten tehuelchus (Bivalvia: Pectinidae) from the south-western Atlantic., figure 1. |