Ontogeny of the intermandibular and hyoid musculature in the suckermouth armoured catfish Ancistrus cf. triradiatus (Loricariidae, Siluriformes)

Abstract

The development of the osteocranium of the suckermouth armored catfish Ancistrus cf. triradiatus is described based on specimens ranging from prehatching stages to juvenile stages where the osteocranium is more or less fully formed. The first bony elements that arise are the opercle, jaws, and lateralmost branchiostegal rays, as well as the basioccipital and parasphenoid in the skull floor. The supracleithrum and the membranous and perichondral pterotic components form one large, double-layered skull bone during ontogeny, without clear evidence of the involvement of a supratemporal. The Baudelot's ligament ossifies from two sides, i.e., from the basioccipital medially and the supracleithrum laterally. The lower jaw consists of a dentary, mentomeckelian, and angulo-articular, which all soon fuse. The parurohyal, formed by the fusion of a ventral sesamoid bone and a dorsal cartilage element associated with the first basibranchial, is pierced by a vein, unlike in some other siluriforms. The interhyal cartilage disappears during ontogeny; medially of it, a small sesamoid bone appears in a ligament. The largest, canal-bearing cheek plate is not homologous to the interopercle. The results of the present research, with emphasis on bone formations and homologies, are compared with studies on related catfishes. J. Morphol. 268:254-274, 2007. 2007 Wiley-Liss, Inc.

A new species of Panaqolus (Siluriformes: Loricariidae) from the rio Branco

“…Anatomical nomenclature follows Schaefer (1987) and Geerinckx et al (2007) for skeletal characteristics, Schaefer (1997) for names of plate rows, and Douglas et al (2002) for the term iris operculum. Institutional abbreviations are as listed in Sabaj Pérez (2014).…”

Ontogeny of the chondrocranium in Corydoras aeneus (Gill, 1858) (Callichthyidae, Siluriformes)

“…The data generated this way were compared to the general trends in siluriforms and to similar data published earlier by Geerinckx et al (2005) on Ancistrus cf. triradiatus, a loricariid representative.…”

“…Some attention has already been paid to the early skeletal ontogenesis of some aspects of the head in other callichthyids (Hoedeman, 1960a,b), but still a lot of detailed information on, e.g., the development of processes, articulations, and foramina is lacking. Since morphogenesis and differentiation are very intense during early life stages, (Van Snik et al, 1997) a thorough knowledge of anatomical ontogeny is of critical importance in understanding the functional trends during early development, since organisms must be functional at each moment, including the early ''temporary'' stages (Fukuhara, 1992;Koumoundouros et al, 2001a,b;Geerinckx et al, 2005).…”

“…In the latter family, the presence of such a suctorial mouth has ultimately led to the formation of an additional highly specialized feeding mechanism (i.e., algae-scraping). In addition to the presence of this suctorial disc in Loricariidae, implications of this specialized apparatus involve tilted lower jaws and new muscle configurations, coupled to increased jaw mobility (Geerinckx et al, 2005). Placed within the evolutionary lineage leading up to these adaptations, the Callichthyidae take a basal position with a ventrally placed mouth already present but with neither the presence of a sucking disc nor an algae-scraping feeding apparatus.…”

“…Therefore, the aim of this study is to provide a complete description of the ontogeny of the chondrocranium in Corydoras aeneus, adding to the wide variety of data on catfish chondrocranial development (Kindred, 1919;Ballantyne, 1930;Bamford, 1948;Srinivasachar, 1957aSrinivasachar, ,b, 1958Srinivasachar, , 1959Hoedeman, 1960a;Vandewalle et al, 1985;Surlemont et al, 1989;Surlemont and Vandewalle, 1991;Verraes, 1994, 1997;Geerinckx et al, 2005) and providing a basis for further ongoing ontogenetic research on this species. The data generated this way were compared to the general trends in siluriforms and to similar data published earlier by Geerinckx et al (2005) on Ancistrus cf.…”