title: A new Brachyrhamdia (Siluriformes: Heptapteridae) from Rio Japurá basin, Brazil, with comments on its phylogenetic affinities, biogeography and mimicry in the genus.
abstract: Brachyrhamdia thayeria is herein described as a new heptapterid species from Rio Japuré, a left margin tributary of the Rio Solimões, Amazonas basin, Brazil. The new species is diagnosed from all its congeners by having a putative autapomorphy: dark oblique stripe across the caudal peduncle, originating below the anterior half of adipose fin and ending at base of rays of ventral caudal-fin lobe. Brachyrhamdia thayeria is considered closely related to B. imitator and B. rambarrani with which it shares a low vertebral number and absence of lateral stripe along trunk. The new species shares exclusively with B. rambarrani the presence of a dark conspicuous bar along the dorsolateral region of trunk, a putative synapomorphy. Brachyrhamdia are distributed in lowland regions of northern South America where they inhabit small streams with running waters. The new species appears to have a mimetic association with the syntopic callichthyid Corydoras arcuatus. Herein, we argue in favor of the hypothesis that the interaction between species of Brachyrhamdia and Pimelodella or Corydoras is Müllerian mimicry.
authors.affiliation: Laboratório de Ictiologia, Museu de Zoologia da Universidade de São Paulo, Caixa Postal 42494, 04218-970 São Paulo, SP Brazil. verorp@gmail.com
authors.forename: Veronica
authors.initials: V
authors.lastname: Slobodian
authors.forename: Flávio Alicino
authors.initials: FA
authors.lastname: Bockmann
mesh_terms: D063147:Animal Distribution; D000818:Animals; D001938:Brazil; D002397:Catfishes / Q000033:anatomy & histology* / Q000145:classification* / Q000235:genetics / Q000502:physiology; D010802:Phylogeny; D045483:Rivers; D013045:Species Specificity