Morphology and development of teeth and epidermal brushes in loricariid catfishes

Abstract

Loricariidae or suckermouth armored catfishes are one of several aquatic taxa feeding on epilithic and epiphytic algae. Their upper and lower jaws bear exquisitely curved teeth, which usually are asymmetrically bicuspid. The enlarged lower lip carries papillae with keratinous unicellular epidermal brushes or unculi. Teeth, and probably unculi too, assist in scraping food off substrates. Their morphology, growth, and replacement is examined and compared among several loricariid species, using cleared and stained specimens, serial sections, and SEM. Apart from the general tooth form and crown shape, the anterior layer of soft tissue on the lower shaft region, present in several species, appears to be a specialization for enhancing the mobility of individual teeth when scraping on uneven surfaces. During early ontogeny, a transition from simple conical to mature tooth occurs. The first unculi appear together with the first teeth carrying a bicuspid crown, 2 days after the first exogenous feeding, but synchronous with the complete resorption of the yolk sac.

Comparative dietary analysis of Eurycheilichthys pantherinus and Pareiorhaphis hystrix: two Loricariidae species (Ostariophysi, Siluriformes) from Campos Sulinos biome, southern Brazil

“…This is an unusual feeding habit among loricariids since they are commonly algivore, herbivore or detritivore due to their tooth shape (SCHAEFER & LAUDER, 1986;LOWE-MCCONNELL, 1999;GEERINCKX et al, 2007). Other studies with Loricariidae species also report a diet based on invertebrates related to the bottom.…”

“…The more expanded lip of E. pantherinus and the presence of accessory unicuspid teeth internally to the main series in the premaxillary and dentary (REIS & SCHAEFER, 1992) make this species apt to explore benthonic resources, differently of the sympatric species P. hystrix, which feed predominantly on detritus possibly because of the lack of accessory teeth and the less expanded shape of the lip (PEREIRA & REIS, 2002). Several studies describe the diversity in number and size of teeth in Loricariidae (MULLER & WEBER, 1992;DELARIVA & AGOSTINHO, 2001;GEERINCKX et al, 2007), showing clearly the possibility of these species to explore different food resources because of their morphological attributes related to feeding behavior.…”

Soft Dentin Results in Unique Flexible Teeth in Scraping Catfishes

“…In fishes, tooth families are defined as series of developmentally successive teeth taking the same place when active, each replacing the previous when that is worn and shed. In loricariid catfishes, tooth families possess up to five replacement teeth on apparently permanent dental laminae, with the highest number of replacement teeth present in species with more slender teeth (Geerinckx et al 2007). This unusually high number likely is an adaptation to the short life span of teeth and to the consequently necessarily high turnover rate of teeth.…”

“…The trait of flexible teeth is rather widely distributed in the loricariid family: it has been found in members of three subfamilies (Geerinckx et al 2007). Inflexible teeth are present in at least two of these subfamilies (species P. nigrolineatus and Rineloricaria parva); numerous loricariid species remain to be tested for tooth properties.…”

“…1; Adriaens et al 2009). Some loricariid species are known to scrape off bits of wood; they have stout, rigid teeth (e.g., Panaque nigrolineatus; Nelson 1999;Geerinckx et al 2007). In several other species of different lineages within the loricariid family, scraping algae or detritus, it was noticed that the gracile teeth have a flexible middle portion, apparently reducing tooth fracture during scraping by somehow bending (Geerinckx et al 2007).…”