Leporinus cylindriformis, OF RECENT YEARS

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

LEPORINUS CYLINDRIFORMIS OF RECENT YEARS : NOT

WHAT WAS THOUGHT

The holotype of L. cylindriformis clearly does not match the series of specimens assigned to that species by Santos & Zuanon (2008), which are referred herein to Leporinus sp. Both linear and geometric methods revealed the L. cylindriformis holotype to have a shallower body than does Leporinus sp. ( Figs 6 , 11 ). The L. cylindriformis holotype falls well outside the 95% confidence ellipse for Leporinus sp. in the scatterplot of PC2 versus PC1 from the geometric analysis. Furthermore, the L. cylindriformis holotype has six scales in the transverse series above the lateral line, whereas all examined specimens of Leporinus sp. have five scales in that series.

It is important to note that the lot of Leporinus sp. examined in this study (INPA 15405) does not appear in the series of comparative material that Santos & Zuanon (2008) assigned to L. cylindriformis during their description of L. amazonicus , presumably because it was on loan to us at the time that they prepared their manuscript. The lot that we examined is from the same general region of Brazil as Santos & Zuanon’s (2008) specimens ( Fig. 12 ) and it was originally identified by staff at INPA as Leporinus cylindriformis . There is no doubt that Santos & Zuanon’s (2008) concept of L. cylindriformis matches the Leporinus sp. of this contribution.

Although Leporinus sp. clearly does not belong to the same species as the L. cylindriformis holotype, its taxonomic status is unresolved. It might represent an undescribed species, but it is morphometrically ( Tables 2 –4) and meristically ( Table 5) indistinguishable from L. cf. niceforoi despite inhabiting a separate region of the Amazon drainage. These two groups also share similar colour patterns. If Leporinus sp. is conspecific with all, or part of, the current concept of L. niceforoi , this would represent a major range extension for L. niceforoi . Many more specimens from a broader geographical range are required to resolve this question. Until such specimens are available, we prefer to put the taxonomic status of Leporinus sp. into abeyance.

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 11. Scatterplot of (A) principal components one and two and (B) principal components one and three from geometric morphometrics after allometric correction. Polygons represent convex hulls surrounding nominal species of Leporinus.

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.