Phylogenetic relationships of the species of Acestridium Haseman, 1911 (Siluriformes: Loricariidae)

Abstract

A phylogeny of the species of the loricariid genus Acestridium and relevant outgroups is presented based on a parsimony analysis of 52 unweighted and unordered morphological characters. Acestridium is diagnosed as monophyletic based on the possession of the 17 exclusive synapomorphies. Two primary trees were found, and the strict consensus among those alternative trees resulted in the following relationships: ((A. dichromum + A. triplax)(A. gymnogaster + A. scutatum + (A. discus (A. colombiensis + A. martini)))). Acestridium was found to be sister to Niobichthys with this clade subsequently the sister-group to Oxyropsis + Hypoptopoma.Uma filogenia das espécies do gênero de Loricariidae Acestridium e grupos externos relevantes é apresentada com base na análise de parcimônia de 52 caracteres morfológicos não pesados e desordenados. Acestridium é diagnosticado como monofilético com base na posse de 17 sinapomorfias exclusivas. Duas árvores primárias foram encontradas e o consenso estrito entre essas árvores alternativas resultou nas seguintes relações: ((A. dichromum + A. triplax)(A. gymnogaster + A. scutatum + (A. discus (A. colombiensis + A. martini)))). Acestridium foi encontrado como grupo-irmão de Niobichthys e este clado como grupo-irmão sucessivo de Oxyropsis + Hypoptopoma.

An appraisal of the phylogenetic relationships of Hypoptopomatini cascudinhos with description of two new genera and three new species (Siluriformes: Loricariidae)

“…Conflicting with the results of Schaefer (1991;, but corroborating results by Rodriguez et al (2015), Acestridium and Niobichthys formed a clade sister to the remaining members of the tribe.…”

“…In the plesiomorphic condition, the neural spine of the sixth vertebral centrum is articulated to the posterior portion of the parieto-supraoccipital, which reinforces the articulation between the vertebral column and cranium (Schaefer, 1987;Rodriguez et al, 2015). Although this articulation is present in most taxa examined, the neural spine of the sixth centrum of Acestridium is small and does not contact the parieto-supraoccipital (state 1).…”

“…The nasal bone forms the mesial rim of the nasal opening, and its position relative to the anterior margin of the lateral ethmoid has a degree of variation (Rodriguez et al, 2015). The anterior margin of the nasal bone may surpass the anterior margin of the lateral ethmoid (state 0) or it can reach the level of or fall short of the anterior margin of the lateral ethmoid (state 1).…”

“…Character 90. Spatulate projection of snout (Rodriguez et al, 2015, char 51): (0) absent; (1) present.…”

“…Rodriguez et al (2015) provided a phylogenetic analysis of the species of Acestridium based on osteology and compared the genus to other members of the Hypoptopomatinae. Inconsistent with the results of Schaefer (1991Schaefer ( , 1998, Rodriguez et al (2015) found Acestridium to be sister to Niobichthys, with that clade subsequently being sister-group to Oxyropsis + Hypoptopoma.…”