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11 November 2015 Variation in the Posttemporal-Supracleithrum Articulation in Euteleosts
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Abstract

A survey of the articulation between two of the dermal elements of the pectoral girdle, the posttemporal and supracleithrum, across 308 euteleost species in 40 orders and 181 families revealed considerable variation. This variation was categorized first by number of distinct contact points, which varied between zero and three. It was then subdivided further into a total of 17 morphotypes based on the observed patterns of variation in the form of these contact points, the plane in which they are oriented, and their relative positions on each bone. Given the distribution of these morphotypes across examined taxa, we hypothesize that a simple laminar morphotype, in which the posttemporal and supracleithrum are syndesmotically bound and no obvious contact points are discernable, represents the plesiomorphic condition. Establishing homology of contact points for many morphotypes remains challenging. However, some morphotypes appear to support previously recognized clades and thus represent putative synapomorphies; these include possession of two contact points (Acanthomorphata) and possession of a specialized three contact point morphotype (Acanthuridae Zanclidae). The posttemporal-supracleithrum articulation is a variable character system that may be phylogenetically informative for future morphological investigations of acanthomorph clades.

© 2015 by the American Society of Ichthyologists and Herpetologists
Nancy I. Holcroft and E. O. Wiley "Variation in the Posttemporal-Supracleithrum Articulation in Euteleosts," Copeia 103(4), 751-770, (11 November 2015). https://doi.org/10.1643/CG-14-099
Received: 5 July 2014; Accepted: 1 April 2015; Published: 11 November 2015
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