Taxonomic revision of SpectracanthicusNijssen & Isbrücker (Loricariidae: Hypostominae: Ancistrini), with description of three new species

Abstract

A taxonomic review of Spectracanthicus Nijssen & Isbrücker, including Oligancistrus Rapp Py-Daniel, following a phylogenetic study, is presented. Additionally to S. punctatissimus (Steindachner) and S. murinus Nijssen & Isbrücker, three new species are recognized based on the examination of 159 specimens: S. immaculatus n. sp. from rio Tapajós basin, differs from its congeners by its color pattern consisting of a dark gray body, with no dots or spots, and by having very slender teeth; Spectracanthicus tocantinensis n. sp., from the rio Tocantins drainage is distinguished by the color pattern consisting of dark brown or black body with small, yellowish dots (except in S. punctatissimus), presence of thick teeth, infraorbital 4 forming most of the posterior edge of the orbit and the large basipterigium fenestrae; and Spectracanthicus zuanoni n. sp., from the rio Xingu basin is diagnosed by its color pattern consisting of large, white spots and by the larger orbital diameter. Other characters based on osteological features are also usefull to distinguish the species. A key to the species of the genus and a brief discussion of their threats and conservation are also provided.A revisão taxonômica de Spectracanthicus Nijssen & Isbrücker, incluindo Oligancistrus Rapp Py-Daniel, baseada em estudos filogenéticos recentes, é apresentada. Adicionalmente a S. punctatissimus (Steindachner) e S. murinus Nijssen & Isbrücker, três espécies novas são reconhecidas baseadas no exame de 159 espécimes: S. immaculatus, sp. n. proveniente da bacia do rio Tapajós, difere de suas congêneres pelo padrão de colorido do corpo cinza escuro sem pontos ou manchas e por possuir dentes bastante delgados; Spectracanthicus tocantinensis sp. n., da bacia do rio Tocantins pode ser distinguida pelo padrão de colorido do corpo marron escuro ou preto com pontos amarelados (exceto de S. punctatissimus), presença de dentes espessos, infraorbital 4 formando quase toda a margem posterior da órbita e pela presença de uma grande fenestra no basipterígio; e Spectracanthicus zuanoni sp. n., da bacia do rio Xingu é diagnosticada pelo padrão de colorido cinza escuro com grandes pontos brancos e por possuir maior diâmetro infraorbital. Outros caracteres osteológicos também podem ser utilizados para distinguir as espécies. Uma chave para as espécies do gênero e uma breve discussão sobre suas ameaças e conservação são também fornecidas.

New species of the genus Spectracanthicus (Loricariidae, Hypostominae, Ancistrini) from the Rio Javaés (Rio Araguaia basin), with a description of gross brain morphology

“…The new species has all these characters, however the anterior process of the metapterygoid is elongate and pointed (not spoon shaped), which also occurs in S. murinus and S. punctatissimus . Others features proposed for the genus by Chamon & Rapp Py‐Daniel () and that also occur in S. javae are: contact between sphenotic and IO6; the elongate anterior metapterygoid process; and the elongate lateropterygium, surpassing the vertical through the anterolateral process of the basipterygium.…”

“…Point-to-point measurements were made to the nearest 0·1 mm with digital callipers on the left side of the specimens, following Chamon & Rapp Py-Daniel (2014). Osteological nomenclature and vertebral counts follow Schaefer (1987), Armbruster (2004) and Geerinckx & Adriaens (2006) for compound pterotic and parieto-supraocciptal bones.…”

A new species of the leopard pleco genus Pseudacanthicus (Siluriformes: Loricariidae) from the Rio Xingu, Brazil

“…Pseudacanthicus pirarara is an important ornamental fish and commercial exploitation has been common practice in the middle to lower Rio Xingu since the 1980s. Such activities are economically profitable in some local communities and in many cases, constitute the entire source of income for multiple families (Camargo et al , ; Chamon & Rapp Py‐Daniel, ). Contrary to the understanding of most people, ornamental fishing activities do not exert a direct effect on the health of such fish communities (Andrews, ; pers.…”

“…Dam construction is a danger to the majority of the ornamental loricariids in the Amazon Basin. The Rio Xingu, like other Amazon tributaries, is suffering from an accelerated rate of dam construction and species that are naturally rare or endemic to specific habitats may suffer drastic population declines and even become extinct in nature (Rapp Py‐Daniel et al , ; Chamon & Rapp Py‐Daniel, ). Scientific understanding of different aspects of the fish fauna of Amazon drainages, including their taxonomy and biology, has not kept pace.…”

“…As a result, rapids in the main channel will be flooded and transformed to a lentic environment. Fishes that live in lotic environments, like P. pirarara , are not adapted to slow flowing or still waters, which are typically lower in oxygen (Chamon & Rapp Py‐Daniel, ; L. M. Sousa, pers. obs.…”