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The systematics of Aconaemys (Rodentia, Octodontidae) and the distribution of A. sagei in Chile

Systematik der Gattung Aconaemys (Rodentia, Octodontidae) und Verbreitung von A. sagei in Chile

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Abstract

The systematic relationships among populations of fossorial Aconaemys species (Rodentia, Octodontidae) were assessed using chromosome variation patterns. Cytogenetic data was used since classical taxonomic studies have yielded contradictory results due to the environmentally induced morphological variation observed in these fossorial rodents. The interpopulational karyotypic stability and lack of intrapopulational polymorphism observed in Aconaemys make chromosome data a good predictor of specific differentiation. A distinct karyotype differing in diploid and number of chromosomal arms (FN) was found at each type locality. This kind and degree of karyotypic differentiation together with molecular data indicate that three species of Aconaemys can be recognized: A. sagei (2 n = 54, FN = 104), A. fuscus (2 n = 56, FN = 108), and A. porteri (2 n = 58, FN = 112). Five populations on the western slope of the Andes (Chile: Nahuelbuta, Tolhuaca, Rio Colorado, Pedregoso, Reigolil, and Huerquehue), formerly ascribed as A. fuscus shared the same karyotype of A sagei from the type locality on the eastern slope of the Andes (Argentina: Pampa Hui-Hui). Thus, karyotypic data let us ascribe these disjunct populations to A. sagei. The classical morpho-species in Aconaemys, altered into the biological species based on chromosomal and molecular differentiation, indicates that all three species occur in Chile. After this survey, the range of A sagei is extended to the northwestern slope of the Andes by more than 300 km.

Zusammenfassung

Die systematischen Beziehungen von Populationen unterirdisch Lebender Aconaemys-Arter (Rodentia, Octodontidae) wurden an Hand chromosomaler Vaniationsmuster untersucht. Die zytoge-netischen Techniken wurden eingesetzt, da klassische taxonomische Studien bisher aufgrund umweltbedingter morphologischer Variation widersprüchliche Ergebnisse geliefert hatten. Die karyotypische Stabilität und das Fehlen eines Polymorphismus innerhalb der Populationen von Aconaemys sprechen für eine diffenentialdiagnostische Brauchbarkeit der Chromosomenvariation für die Unterscheidung von Arten. Für jeden lokalen Typus ergaben sich deutlich unterschiedliche Karyotypen sowohl hinsichtlich der diploiden Chromosomenzahl als auch hinsichtlich der Zahl der Chromosomenarme (FN). Nach der karyotypischen und molekularen Differenzierung ergeben sich drei Arten für die Gattung Aconaemys: A. sagei (2 n = 54, FN = 104), A. fuscus (2 n = 56, FN = 108) und A. porteni (2 n = 58, FN = 112). Fünf Populationen am westlichen Hang der Anden (Chile: Nahuelbuta, Tolhuaca, Rio Colorado, Pedregoso, ReigoLiL und Huerquehue), die bisher A. fuscus zugeschrieben wurden, zeigten denselben Karyotyp wie A. sagei von der Typus-Lokalität am östlichen Hang der Anden (Argentinien: Pampa Hui-Hui). Die karyotypischen Daten erlauben somit eine Zuordnung der disjunkten Populationen zu A. sagei. Die klassischen Morphospezies von Aconaemys, biologisch umrissen durch chromosomale und molekulare Daten, kommen alle drei in Chile vor. Unsere Daten weisen daraufhin, daß das Verbreitungsgebiet von A. sagei über mehr als 300 km bis zum nordwestlichen Hang der Anden erweitert werden muß.

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  1. Institute de Ecología y Evolución, Universidad Austral de Chile, Casilla 567, Valdivia, Chile

    M. H. Gallardo & F. Mondaca

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  1. M. H. Gallardo
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  2. F. Mondaca
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Correspondence to M. H. Gallardo.

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Gallardo, M.H., Mondaca, F. The systematics of Aconaemys (Rodentia, Octodontidae) and the distribution of A. sagei in Chile. Mamm Biol 67, 105–112 (2002). https://doi.org/10.1078/1616-5047-00015

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