Redescription and First Nucleotide Sequences of Rhinobatonchocotyle pacifica Oliva & Luque, 1995 (Monogenea: Hexabothriidae), a Parasite of Pseudobatos planiceps (Garman, 1880) (Rhinopristiformes: Rhinobatidae) from Peru.

Introduction: Specimens of Rhinobatonchocotyle pacifica Oliva & Luque, 1995 (Hexabothriidae) were collected from the gill filaments of Pacific guitarfish, Pseudobatos planiceps (Garman, 1880) (Rhinopristiformes: Rhinobatidae), from off the coast of Chorrillos, Lima, Peru. Since the original description of R. pacifica was incomplete, we herein redescribe R. pacifica based on re-examination of the holotype, paratypes, and newly collected voucher specimens. Nucleotide sequences (18S, 28S) for R. pacifica are presented for the first time, and a phylogenetic analysis conducted.
Materials and Methods: Monogeneans were examined with light microscopy and partial sequences of 18S and 28S rDNA genes were obtained.
Results: The following taxonomically important morphological features are described: presence of seminal receptacle, spiniform papillae within oral cavity, haptoral sucker sclerites and anchors, hook surface striations, muscular pad associated with each haptoral sucker sclerite (except sclerite 1), muscular bulbs in appendix suckers, and oötype lacking longitudinal rows of large cells (oötype not côtelé). The genital complex is detailed. The diagnosis of Rhinobatonchocotyle is emended to include species with or without seminal receptacle. Representative nucleotide sequences of partial 18S and 28S rDNA genes of R. pacifica were obtained for the first time and used for reconstructing the phylogeny of Hexabothriidae.
Conclusion: The phylogenetic reconstruction confirmed the species within the Hexabothriidae.