Leporacanthicus Isbrücker and Nijssen, 1989


Leporacanthicus triactis, photo by M.H. Sabaj

Leporacnthicus sp. cf. galaxias, photo by M.H. Sabaj

TAXA LIST


The following is an excerpt from Armbruster (1997).


SPECIES



DIAGNOSIS

Leporacanthicus is diagnosed by three unique characteristics: large foramina in the anterohyal, a small cartilage just posterior to the mesethmoid disk, and a long foraminal section of the prootic.  Other characteristics considered synapomorphic for Leporacanthicus are: reduction in the length and width of the accessory process of the first ceratobranchial to 3/4 the length of the main body and thin, loss of the posterior wall of the fourth epibranchial, elongated first hypobranchials, posterior position of the interohyal, long pharyngeal teeth, loss of the posterior pouch of the posterohyal, a dorsal foramen on the hyomandibula, the levator arcus palatini crest terminating dorsal to the metapterygoid facet for articulation with the lateral ethmoid, loss of the raised triangular section at the junction of the levator arcus palatini crest and the preoperculo-hyomandibular ridge, a mesial ridge at the anterodorsal corner of the metapterygoid facing anteriorly, loss of contact of the metapterygoid facet and the lateral wall of the pterygoid channel, a tall supraoccipital crest, presence of a cartilage at the anterior corner of the mandible, a straight, bowling-pin shaped maxilla, a large canal plate that deflects under the head, the lateral line continuing onto the plate beyond the hypurals, reduction in the size of the ossified Baudelotís ligament to a short shelf, the metapterygoid condyle of the lateral ethmoid forming a lateral shelf, thick ribs, four or more predorsal plates, loss of abdominal plating, and barbels over the upper jaws.



DESCRIPTION

Called the vampire plecostomus in the aquarium literature in reference to the large teeth in the upper jaw.  Species of Leporacanthicus are medium-sized loricariids with a narrow, pointed head, round lower lip, and fleshy tentacles on the upper lip.  Color pattern is generally dark gray to black with white to golden spots or a light gray with medium-sized black spots.  Abdomen naked.  Caudal fin straight, angled posteroventrally.  Three predorsal plates.  Two teeth per premaxilla that are much longer than the dentary teeth.



COMPARISONS

Leporacanthicus is readily identifiable from all other Ancistrini by the development of usually only two teeth in each premaxilla, the inner teeth being very long (all other Ancistrini have more than two teeth in the premaxilla), by having a well-raised supraoccipital crest (the supraoccipital in most of the Ancistrini is flat to slightly raised) and by having numerous long fimbriae above the upper jaws.  Leporacanthicus looks most similar to some Panaque, Spectracanthicus, and Megalancistrus, and Pseudacanthicus from which it can also be identified by a round lower lip (vs. oval) and fimbriae on the upper lip.  In addition, Spectracanthicus has the dorsal fin connected to the adipose fin spine (well separated in Leporacanthicus) and Panaque has a wide, rounded head (vs. pointed and narrow in Leporacanthicus) and much stouter teeth.

Mouth of Leporacanthicus sp. cf. galaxias showing the fimbriae of the upper lip, the round lips, and the very long premaxillar teeth (just one on each side in this specimen). Photo by M.H. Sabaj.



DISTRIBUTION

The genus has been reported from the upper Orinoco, the eastern, north-flowing Amazon tributaries, and the Rio Tocantins (Stawikowski, 1992).


ECOLOGY

The type of L. triactis was pulled from a deep hole in a mud bank (L. Nico, pers. comm.).  It has been hypothesized that the enlarged teeth of the upper jaw are used to remove snails from their shells (Burgess 1994). We have observed this in L. joselimai, but specimens from Venezuela seem to have a lot of caddis flies in the gut as well as freshwater sponges.



LITERATURE CITED

Armbruster, J.W. 1997. Phylogenetic relationships of the sucker-mouth armored catfishes (Loricariidae) with particular emphasis on the Ancistrinae, Hypostominae, and Neoplecostominae. Unpubl. Ph.D. dissertation. University of Illinois, Urbana-Champaign. 409 pp.

Burgess, W.E. 1994. Scobinancistrus aureatus, a new species of loricariid catfish from the Rio Xingu (Loricariidae: Ancistrinae). Tropical Fish Hobbyist 43:236?242.

Stawikowski, R. 1992. Die Gattung Leporacanthicus Isbrücker & Nijssen, 1989. Harnischwelse, DATZ-Sonderheft, September 1992: 58-61.


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