Leporinus niceforoi, : ONE

Sidlauskas, Brian L, Mol, Jan H. & Vari, Richard P., 2011, 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, Zoological Journal of the Linnean Society 162 (1), pp. 103-130 : 126-127

LEPORINUS NICEFOROI: ONE SPECIES OR TWO?

Surprisingly, traditional linear morphometrics suggest that the holotype and paratype of L. niceforoi from Colombia are separable from putative conspecifics from Ecuador and Peru ( L. cf. niceforoi ) on the basis of the more slender bodies in the two Colombian specimens. These type specimens fall well outside the range of L. cf. niceforoi on the PC2 from traditional morphometrics ( Fig. 6 ), and Tukey’s post-hoc test on the PC2 scores returned a P -value of 0.0001 for separation of these two groups ( Table 3). Indeed, simple examination of the ratios of body depth in standard length ( Table 6) reveals that the types of L. niceforoi fall within the range of L. apollo and L. cylindriformis , which are the two most dorsoventrally slender examined species in the genus. As only the two type specimens of L. niceforoi are available, the regressionbased test for variation in the intercept of the linear PC1 as reported in Table 2 cannot be performed for this group. Furthermore, because the specimens are bent, these specimens cannot be included in the geometric morphometric analysis. Other than the morphometric difference and the slight geographical separation ( Fig. 12 ), L. cf. niceforoi and L. niceforoi have identical colour patterns and meristic counts ( Table 5).

Although the presence of two cryptic species within the current concept of L. niceforoi is a possible explanation for the described differences in body depth, at least two other scenarios are possible. First, a morphocline may exist within this species, which would be revealed by the incorporation of more extensive geographical samples of specimens. Second, the type specimens may have shrunk over the course of more than 70 years of storage ( Buchheister & Wilson, 2005; Thorstad et al., 2007). Only the examination of recently collected material from at or near the type locality in Colombia complemented by additional samples from Peru and Ecuador will resolve these questions.

Figures

Figure 6. Scatterplot of principal component two (PC2) versus one from traditional linear morphometrics for species of Leporinus discussed in text. PC1 is an allometric vector describing size and shape variation, whereas PC2 is essentially size-free. Polygons indicate convex hulls.

Figure 12. Geographical distribution of examined specimens of Leporinus amazonicus, Leporinus apollo sp. nov., Leporinus cylindriformis, Leporinus niceforoi, Leporinus cf. niceforoi, and Leporinus sp. Some symbols represent more than one collection locality.