Methods employed in the morphological study of the Antartic limpet Nacella concinna: does a new technique show better results?

SANTIAGO CASTILLO; MARÍA CARLA DE ARANZAMENDI; JUAN JOSÉ MARTÍNEZ

La Falda, Córdoba

Jornada; XXI Annual Scientific Meeting; 2018

Sociedad de Biología de Córdoba

Nacella concinna is one of the most abundant macro-invertebrates of the Antarctic Peninsula, where it can be found from the coast to 100 m deep. Two morphotypes have been described based on the shell morphology and the platform zone in which they inhabit. The tidal morphotype has a tall and globose shell, while the subtidal morphotype shell is flatter. Traditionally, linear measurements were used to differentiate between individuals of both morphotypes. However, Elliptic Fourier Analysis (EFA) based on the contour of shells has shown interesting results in this and other species. In this work, we evaluated the differences between these two usually used morphometric methodologies. The maximum high, maximum length and maximum width were measured in tidal and subtidal individuals; EFA was performed in lateral and dorsal views. The results obtained were similar between traditional morphometry and lateral EFA, even though the latter presents a better resolution. Dorsal EFA does not provide much useful information to differentiate between morphotypes. Although the use of traditional morphometry proved to be a reliable tool to differentiate the morphs of this species, the lateral EFA would be the most appropriate methodology for the study of morphological variation and the distinction of morphotypes. This is because lateral EFA evaluates the plane formed by the maximum axes of variation between morphs, allowing a better characterization of the shape changes.