Methods
Standard counts and measurements were recorded following the procedures of
Taylor and Miller (1980). Measurements and qualitative shape descriptions of
pharyngeal jaws were taken from Barel et al. (1977) with the following additions:
mid-pharyngeal jaw width (MPW) is the distance between the margins of the
dentigerous area of the lower pharyngeal jaw at the midpoint of lower pharyngeal
length parallel to the line of measured lower pharyngeal width; pharyngeal jaw
horn width (PHW) is the maximum distance across one horn (ramus) of the lower
pharyngeal jaw. Head width (HW) is the maximum distance between opercula
measured over the body (with no caliper compression) at the central, fullest
portion of the operculum.