A new genus and two new species of Stevardiinae (Characiformes: Characidae) with a hypothesis on their relationships based on morphological and histological data

Katiane M Ferreira,Naércio A Menezes,Irani Quagio-Grassioto

doi:10.1590/s1679-62252011000200005

Katiane M Ferreira, Naércio A Menezes + Show 1 more

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https://doi.org/10.1590/s1679-62252011000200005

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Abstract

Lepidocharax, new genus, and Lepidocharax diamantina and L. burnsi new species from eastern Brazil are described herein. Lepidocharax is considered a monophyletic genus of the Stevardiinae and can be distinguished from the other members of this subfamily except Planaltina, Pseudocorynopoma, and Xenurobrycon by having the dorsal-fin origin vertically aligned with the anal-fin origin, vs. dorsal fin origin anterior or posterior to anal-fin origin. Additionally the new genus can be distinguished from those three genera by not having the scales extending over the ventral caudal-fin lobe modified to form the dorsal border of the pheromone pouch organ or to represent a pouch scale in sexually mature males. In this paper, we describe these two recently discovered species and the ultrastructure of their spermatozoa.

Highlights

The presence of glandular tissue associated with modified scales on the caudal-fin of sexually mature males was used by Eigenmann (1914) to characterize the Glandulocaudinae, a group initially thought to be monophyletic, but recently split into two subfamilies: Glandulocaudinae and Stevardiinae (Menezes & Weitzman, 2009)
According to Weitzman et al (2005), the Stevardiinae can be separated from the Glandulocaudinae by three characters: 1) presence in the Stevardiinae and in the genus Knodus of a hypertrophic extension of the body scales onto the rays of ventral caudal-fin lobe which is absent in all Glandulocaudinae; 2) caudal organs of the species of the Glandulocaudinae with a hypertrophic extension of the upper lobe body scales onto the rays of the dorsal caudalfin lobe rather than the lower caudal-fin lobe as in the Stevardiinae tribes; and 3) caudal-gland cells of the caudal organ of the Glandulocaudinae consisting of apparently specialized club cells, not the modified mucous cells reported for some Stevardiinae
The other was collected in several tributaries of the upper rio São Francisco. We describe these two recently discovered species and briefly discuss their phylogenetic relationships within the Stevardiinae based on osteological and histological characters

Summary

Introduction

The presence of glandular tissue associated with modified scales on the caudal-fin of sexually mature males was used by Eigenmann (1914) to characterize the Glandulocaudinae, a group initially thought to be monophyletic, but recently split into two subfamilies: Glandulocaudinae and Stevardiinae (Menezes & Weitzman, 2009). Based mainly on the analysis of osteological characters Mirande (2010) proposed a new phylogenetic arrangement for members of the Characidae and considered the Stevardiinae a more inclusive group composed of all the genera belonging to Clade A of Malabarba & Weitzman (2003), plus the genera Aulixidens, Bryconadenos, and Nantis. According to this phylogenetic arrangement the Glandulocaudinae and Stevardiinae of Weitzman et al (2005) and Menezes & Weitzman (2009) would have to be considered subgroups within Mirande’s Stevardiinae.

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