Rhinelepini, Armbruster 2004

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Pogonopoma
Photo by K.S. Cummings

Pseudorinelepis
Photo by K.S. Cummings

Rhinelepis
Photo by K.S. Cummings
TAXA LIST


The Rhinelepis Group was defined as a monophyletic group by Armbruster 1998 based on the derived presence of a U-shaped esophageal diverticulum among many other characteristics and was diagnosed as a tribe, Rhinelepini, in Armbruster (2004).  It is one of the best diagnosed groups in all of Loricariidae.  The following information is an excerpt from Armbruster (1998).


DIAGNOSIS

[Characters in parentheses are from Armbruster, 1998].  The Rhinelepis group is diagnosed by several synapomorphies: a lateral shelf of the upper pharyngeal tooth plate (4-1); an elongated mesial process of the palatine (7-1); a symplectic foramen that has shifted dorsally such that the anterodorsal margin is formed by the quadrate (10-1); lack of ribs beyond the enlarged rib of the sixth vertebral centrum (24-1); loss of the adipose fin (25-1); an exposed portion of the coracoid strut (29-1); widened lateral processes of the pelvic basipterygium (31-1); circular (vs. bilobed) pupils (36-0); a straight esophagus to which the intestine does not pass dorsally (39-1); and a large, U-shaped, two-part diverticulum of the digestive tract (40-1).  Within the Rhinelepis group, the clade of Pogonopoma, Pogonopomoides, and Rhinelepis is diagnosed by a lateral process on the second infrapharyngobranchial (2-1); an angled preopercle (8-1); an anterior exit of the preopercular canal (9-1); a patch of small plates posterior to the pterotic-supracleithrum (38-1); and a diverticulum that has become firmly attached to the abdominal wall (40-2).  Pogonopoma + Pogonopomoides is diagnosed by contact of the hyomandibular condyle solely to the pterotic-supracleithrum (5-1); a taller lateral than mesial wall of the pterygoid channel (6-1); a sesamoid ossification located in the interoperculo-mandibular ligament (13-0 and 14-0); bifid hemal spines (23-0); reduction of the anteroventral ridge of the pelvic basipterygium (32-1); pointed posterior processes of the pelvic basipterygium (33-1); and a diverticulum that has become retroperitoneal, non-expandable, and has a reduced first section (40-3).



DESCRIPTION

The Rhinelepis group is an assemblage of four genera, with medium- to large-sized species.  The Rhinelepis group is unique among loricariids for possessing a round (normal) pupil versus a bilobed pupil (although it is often hard to see the flap of skin in bilobed, preserved fishes).  The species have thick plates.  The anus is placed far posteriorly so that it is just anterior to the anal fin.  The teeth are fairly unique among loricariids in that they are usually numerous (up to 96) and have stalks that are much longer than those seen in other loricariids.  In Pogonopoma, Pogonopomoides, and Pseudorinelepis, the crowns of the teeth are small, but otherwise shaped like most loricariids (a large mesial and a small lateral cusp).  In Rhinelepis, the mesial cusp is long and thin and the lateral cusp is often absent making the teeth look peg-like.



COMPARISONS

The Rhinelepis group can be distinguished from other Hypostominae by a combination of the following characters: five branched anal fin rays; lack of postdorsal ridge formed of raised, median, unpaired plates; an exposed portion of the coracoid strut of the pectoral girdle; a circular (vs. bilobed) pupil; and if elongate odontodes are present on the head, they are developed in a large, nonevertible patch.



DISTRIBUTION

Known from the Rios Amazon, Mucuri, Paraná, Paraíba, São Francisco, and Uruguay drainages in Brazil and Peru.

The question mark refers to a potentially introduced population of Rhinelepis.



LITERATURE CITED

Armbruster, J.W. 1998. Phylogenetic relationships of the suckermouth armored catfishes of the Rhinelepis group (Loricariidae: Hypostominae). Copeia 1998:620-636.


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