DOI: 10.5061/dryad.8151
title: Data from: Dealing with allometry in linear and geometric morphometrics: a taxonomic case study in the Leporinus cylindriformis group (Characiformes: Anostomidae) with description of a new species from Suriname

description: To achieve maximum efficacy, taxonomic studies that seek to distinguish
 amongst species must first account for allometric shape variation within
 species. Two recently developed software packages (SMATR and MorphoJ)
 offer regression-based allometric approaches that are notable for their
 statistical power and ease of use and that may prove highly useful to
 taxonomists working with linear or geometric morphometric data. We
 investigate species delimitation of the slender-bodied fishes in the
 Leporinus cylindriformis group using these programs and demonstrate the
 utility of the allometric corrections that they provide. Without
 allometric correction, many pairs of species are difficult to distinguish
 on the basis of morphometrics, but once regressions are used to account
 for marked allometric variation within species, most of the recognized
 species in this group can be readily distinguished with linear or
 geometric morphometrics, particularly using variation in the depth of the
 body. Both approaches returned congruent patterns of separation amongst
 putative species, but the geometric approach in MorphoJ distinguished
 amongst four more pairs of species than did the linear approach in SMATR
 and appears to provide slightly more statistical power. Based on
 distinctive morphometrics, meristics, and coloration, a highly elongate
 species of Leporinus from the Suriname, Corantijn, and Coppename rivers of
 Suriname is described herein as a new species, Leporinus apollo sp. nov.
 The unique L. cylindriformis holotype from Porto de Moz, Brazil differs in
 morphology, meristics, and pigmentation from specimens commonly referred
 to that species from the main basin of the Amazon; the latter specimens
 may represent an additional undescribed species. The L. cylindriformis
 holotype itself may represent a rare species or a specimen collected at
 the edge of its native range. Measurements of the holotype and paratype of
 Leporinus niceforoi, which were collected in the Amazonian slope of
 Colombia, differ substantially from similarly pigmented and putatively
 conspecific specimens from Amazonian portions of Ecuador and Peru.
 Recently collected specimens from Colombia are needed to determine whether
 the observed morphometric variation encompassed by the current concept of
 L. niceforoi indicates a morphocline within a single species, suggests the
 presence of multiple cryptic species, or results from shrinkage of the
 types. In all these cases, linear or geometric morphometric data can
 reliably differentiate amongst species, but only after one accounts for
 allometric shape variation. The new SMATR and MorphoJ software packages
 both offer easy and effective approaches to such allometrically informed
 taxonomy, and may prove useful to any systematist working on taxa that
 change shape as they grow.
description: Leporinus_cylindriformisGeometric morphometric data and analysis. This file can be opened using Chris Klingenberg's free software MorphoJ, available at http://www.flywings.org.uk/MorphoJ_page.htmLeporinus_linear_morphometricsCaliper-based linear morphometric data and analysis. MS Excel format.Leporinus_meristicsMeristic (counted) data for scales, teeth and fin rays.