In addition to that squamation, all those genera can be partly or exclusively diagnosed or defined by other remarkable features associated with bony hooks, caudal muscles, and spur-shaped structures (Arcila, Vari, & Menezes, 2013 Menezes & Weitzman, 2009 Vanegas-Ríos, 2018 Weitzman & Fink, 1985 Weitzman & Menezes, 1998 Weitzman, Menezes, Evers, & Burns, 2005 Zarske, 2010). Within the Stevardiinae, the presence of a hypertrophied terminal caudal-fin squamation either present in both sexes or restricted to adult males (Menezes & Weitzman, 2009 Vanegas-Ríos, 2018 Weitzman & Fink Trochilocharax Zarske Tyttocharax Fowler and Xenurobrycon Myers & Miranda-Ribeiro. This Subfamily is distributed in freshwaters of eastern and southern Brazil, Paraguay, and northeastern Uruguay. The club cells are associated with somewhat modified to highly derived caudal scales forming a pheromone pumping organ in the more derived genera and species. Gland cells found in the caudal-fin organs of all species are histologically indistinguishable from club cells and probably secrete a pheromone during courtship. A replacement name, Glandulocauda caerulea Menezes & Weitzman, is proposed for G. Glandulocauda melanogenys Eigenmann, 1911, is considered a junior synonym of Hyphessobrycon melanopleurus Ellis, 1911.
The Subfamily Glandulocaudinae consists of three genera: Lophiobrycon with one species plesiomorphic in some anatomical features but some others exclusively derived relative to the species in the other genera Glandulocauda with two species intermediate in phylogenetic derivation and Mimagoniates with seven species (one new), all more phylogenetically derived concerning their pheromone producing caudal-fin organs and with other anatomical characters presumably more derived than in the species of the other genera.
The systematics of the Glandulocaudinae is reviewed in detail and justification for the recognition of the group as a Subfamily is discussed.
0 kommentar(er)
