Miniaturization in Otothyris Myers, 1927 (Loricariidae: Hypoptopomatinae)

Abstract

Many species of freshwater fishes are considered miniatures, nevertheless, their identification as miniatures is frequently based only on an arbitrary criterion of small body size. Although some species of Otothyris had been suggested to be miniature, informations about the process and consequences of miniaturization in the genus are lacking. Here, we detail developmental events of loss, fusion, and modifications in several bones, the laterosensory system, and even the brain, that in sum demonstrate miniaturization in all species of the genus. Our results may be useful in the recognition of other miniature species of loricariids.Muitas espécies de peixes de água doce são consideradas miniaturas, entretanto, sua identificação é frequentemente baseada apenas no critério arbitrário que é seu reduzido tamanho corporal. Apesar de algumas espécies de Otothyris terem sido propostas como miniaturas, informações acerca do processo de miniaturização no gênero e suas consequências são escassas. Aqui detalhamos eventos de perda, fusão, modificações em muitos ossos, sistema laterossensorial e no cérebro, que juntos evidenciam a miniaturização em todas as espécies do gênero. Nossos resultados podem ser úteis na identificação de outras espécies miniaturas dentro de Loricariidae.

Gross anatomy and histology of the alimentary system of Characidae (Teleostei: Ostariophysi: Characiformes) and potential phylogenetic information

“…Also it is relevant to note that those species with omnivorous diets herein mentioned seems to have a tendency to a greater development of their liver and pancreas. This means that, in general terms, herbivorous species have a greater portion of its body devoted to feeding and in consequence it may be expected from this, that miniature species are more likely to evolve in "carnivorous clades", or less likely to occur in herbivorous ones, although herbivorous miniatures do occur as in the case of Otothyris (Loricariidae) (Rosa et al, 2014), for example.…”

Gross morphology of the brain of Pseudopimelodus bufonius (Valenciennes, 1840) (Siluriformes: Pseudopimelodidae)

“…The brain anatomy of the Callichthyidae and its relation to the phylogeny of the group was discussed by Pupo (2011), and recently, Rosa et al (2014) detailed the gross morphology of the brain of Neotropical catfi hes. The systematics and anatomy of the Pseudopimelodidae have been the subject of several studies (e.g., Lundberg et al, 1991;Shibatta, 1998Shibatta, , 2003Birindelli & Shibatta, 2011), but descriptions of the gross morphology of the brain in the group (and of the Siluriformes as a whole) remain scarce.…”

Redescription of the endangered hypoptopomatine catfish Parotocinclus spilurus (Fowler, 1941) (Siluriformes: Loricariidae) from the upper rio Jaguaribe basin, northeastern Brazil

“…3). Ontogenetic shape changes were already observed in loricariids, including hypoptopomatine catfishes (Aquino & Miquelarena, 2001;Rosa et al, 2014) and must be related to allometric development of bones, muscles and plates structures (Geerinckx et al, 2008(Geerinckx et al, , 2009.…”