Journal Article
Genetic and morphological evidence cast doubt on the validity of Mexican troglobitic species of the Neotropical catfish genus Rhamdia (Siluriformes: Heptapteridae).
Arroyave, J. and De La Cruz Fernández, D.A.
Record Number:
5252
Year:
2021
Journal:
Revista Mexicana de Biodiversidad
Pages:
1-32
Volume:
92:e923718
Notes:
Open Access bajo la licencia CC BY-NC-ND (4.0)
Abstract:
Four of the 7 species of Rhamdia present in Mexico stand out for being microendemic and also troglobitic, that
is, for being restricted to their type-locality caves and for exhibiting a distinctive phenotype characterized by ocular
reduction/loss and body depigmentation. Diagnosis and recognition of Mexican troglobitic forms as distinct species,
however, appears to be primarily based on their regressive troglomorphic phenotype and highly localized geographic
distributions. To test the adequacy of its current taxonomy, we investigated patterns of genetic and phenotypic variation
in Mexican troglobitic Rhamdia in a phylogenetic context. Our results indicate that external morphology does not allow
for unambiguous differential diagnoses and robust distinction among troglobitic species. Similarly, beyond typical
regressive troglomorphic traits, troglobitic species do not differ greatly in external morphology from their most closely
related congener, the epigean species Rhamdia laticauda. From a phylogenetic perspective, continued recognition of
troglobitic species implies a deep and generalized paraphyly in R. laticauda. Despite the evidence presented herein,
we refrain from making nomenclatural decisions until we can unambiguously ascertain that our findings are indeed
explained by phylogeographic structure in R. laticauda, instead of by recent divergence and subsequent speciation of
cave-dwelling lineages from this widespread epigean species.
Keywords: Rhamdia reddelli; Rhamdia zongolicensis; Rhamdia macuspanensis; Rhamdia laluchensis; Troglomorphism;
Cave fishes; DNA barcoding; Geometric morphometrics
Times Cited:
4