Cichlids of the tribe Heroini have long been a source of taxonomical conflict. In particular, the species included in the Herichthys bartoni group have failed to be recovered as monophyletic in different molecular studies. In this paper we use traditional and geometric morphometrics to evaluate morphological variation in the species included in the H. bartoni complex in order to evaluate the number of species it contains. An update of a previously published DNA barcoding study suggests the existence of three genetic clusters that included the six recognized species analyzed in this study, none of them recovered as monophyletic. On the other hand, geometric morphometrics arise as a useful tool to discriminate species due that traditional morphometrics showed a high overlap in the characters analyzed that prevents the proposal of diagnostic characters.Los cíclidos de la tribu Heroini han experimentado un largo conflicto taxonómico. En particular, las especies incluidas en el grupo Herichthys bartoni no han sido recuperadas como monofiléticas en diversos estudios moleculares. En este artículo nosotros usamos morfometría tradicional y geométrica para evaluar la variación morfológica de las especies incluidas en el complejo H. bartoni para evaluar el numero de especies que contiene. Una actualización de un estudio previo de código de barras de ADN sugiere la existencia de tres grupos genéticos que incluyen las seis especies reconocidas analizadas en este estudio, ninguna de las cuales fue recuperada como monofilética. Por otro lado, la morfometría geométrica surge como una herramienta de utilidad para discriminar especies debido a que la variación en caracteres morfométricos tradicionales muestra altos niveles de solapamiento que previene la propuesta de caracteres diagnósticos.

We provide a review of the systematics of Herichthys by evaluating the usefulness of several mitochondrial and nuclear genetic markers together with morphological data. The nDNA next‐generation sequencing ddRAD analysis together with the mtDNA cytochrome b gene provided well‐resolved and well‐supported phylogenies of Herichthys. On the other hand, the nDNA S7 introns have limited resolution and support and the COI barcoding analysis completely failed to recover all but one species of Herichthys as monophyletic. The COI barcoding as currently implemented is thus insufficient to distinguish clearly distinct species in the genus Herichthys that are supported by other molecular markers and by morphological characters. Based on our results, Herichthys is composed of 11 species and includes two main clades (the H. labridens and H. cyanoguttatus species groups). Herichthys bartoni is in many respects the most plesiomorphic species in the genus and has a conflicting phylogenetic position between mtDNA and nDNA markers, where the robust nDNA ddRAD data place it as a rather distant basal member of the H. labridens species group. The mtDNA of H. bartoni is on the other hand only slightly divergent from the sympatric and syntopic H. labridens, and the species thus probably have hybridized in the relatively recent past. The sympatric and syntopic Herichthys steindachneri and H. pame are supported as sister species. The Herichthys cyanoguttatus species group shows two well‐separated basal species (the northernmost H. minckleyi and the southernmost H. deppii) followed by the closely related and centrally distributed species H. cyanoguttatus, H. tepehua, H. carpintis, and H. tamasopoensis whose relationships differ between analyses and show likely hybridizations between themselves and the two basal species as suggested by conflicts between DNA analyses. Several instances of introgressions/hybridizations have also been found between the two main clades of Herichthys.

In the present study we evaluated the putative cases of sympatric speciation in the genus Herichthys by studying the variation in head shape using principal component analysis, phylomorphospace and reconstructions of the ancestral states of feeding preferences. Herichthys includes both allopatric and sympatric sister species, as well as sympatric unrelated species and thus offers great potential for evolutionary studies of putatively sympatric speciation. Herichthys is the northernmost group of cichlids in America and one of the most ecologically disparate genera within Middle American cichlids. Fifteen anatomical points were recorded on the heads of 293 specimens of the 11 species recognized within the genus. The results show that in spite of having wide variation in consumed diets, most species of Herichthys are close in morphospace. However, morphological variation was great among the two pairs of sympatric sister species in agreement with the suggested sympatric model of speciation.

Using molecular dated phylogenies and biogeographic reconstructions, the species diversity, biogeography and time frame of evolution of the genus Herichthys were evaluated. In particular, we test the role of Punta del Morro (PdM) as a vicariant brake along the Mexican Transition Zone in the context of local and global time frame of cichlid diversification using several sets of calibrations. Species diversity in Herichthys is complex and the here employed dating methods suggest young age and rapid divergence for many species while species delimitation methods did not resolve these young species including both sympatric species pairs. Based on our molecular clock dating analyses, Herichthys has colonized its present distribution area significantly prior to the suggested vicariance by PdM (10–17.1 Ma vs. 5 to 7.5 Ma). The PdM constraint is in conflict with all other paleogeographic and fossil constraints including novel ones introduced in this study that are, however, congruent among each other. Our study demonstrates that any cichlid datings significantly older or younger than the bounds presented by our analyses and discussion have to be taken as highly questionable from the point of view of Middle American paleogeography and cichlid biogeography unless we allow the option that cichlid biogeography is completely independent from ecological and geological constraints.

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