Phylogenetic assessment ofThatcher & Varella, 1981 (Digenea: Haploporidae) from(Siluriformes: Loricariidae) in the Peruvian Amazon Basin.

Abstract

This study provides the first integrative analysis ofThatcher & Varella, 1981 (Digenea: Haploporidae) from the Amazon sailfin catfishCastelnau, 1855 (Siluriformes: Loricariidae) in the Peruvian Amazon. A detailed morphological description is presented, including the first scanning electron microscopy (SEM) images of tegumental structures, which revealed two distinct types of tegumental spines: (1) small, button-like spines and (2) sharply pointed spines. Partial sequences of the 28S rDNA and mitochondrial cox1 genes were generated and analysed to investigate the phylogenetic position ofSzidat, 1954, within the Haploporidae Nicoll, 1914. Phylogenetic analyses placedwithin the 'robust species' clade ofSzidat, 1954, clustering withSzidat, 1973, although with weak support. These results provide additional evidence thatis not monophyletic and support restricting the genus to the 'minute species' clade containing the type species. The 'robust species' clade appears to comprise at least three divergent lineages, potentially representing distinct genera, one of which includesThe absence of molecular data forSzidat, 1954, the type species of, continues to obscure its phylogenetic placement. We highlight the need for comprehensive morphological and multilocus molecular analyses, including SEM, to clarify the taxonomic status ofand to resolve the evolutionary relationships of chalcinotrematine digeneans in Neotropical fishes.