Hypancistrus

Hypancistrus Isbrücker and Nijssen, 1991

Hypancistrus zebra, holotype photo by J.W. Armbruster

Hypancistrus inspector, holotype, Photo by J.W. Armbruster

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ABOUT

KEY

Hypancistrus was originally described for the very boldly striped Hypancistrus zebra, but this description has barely scraped the surface of this incredibly diverse genus. Armbruster (2001) described H. inspector, which now turns out to be two different species (one in the Negro and one in the Orinoco). In addition, at least four other species need to be described from Venezuela, one from Guyana, and many from Brazil (including the so-called Queen Arabesque Pleco). Below are some pictures of some of the diversity that remains to be described in Hypancistrus. We just published a manuscript describing at four of the new species from Venezuela, but there are a lot more out there (Armbruster et al. 2007). Although Armbruster (2004) did not find Hypancistrus to be monophyletic, my recent analyses do have a monophyletic Hypancistrus. The following is an excerpt from Armbruster (2002) and Armbruster et al. (2007).

SPECIES

H. contradens Armbruster, Lujan, and Taphorn 2007
H. debilittera Armbruster, Lujan, and Taphorn 2007
H. furunculus Armbruster, Lujan, and Taphorn 2007
H. lunaorum Armbruster, Lujan, and Taphorn 2007
H. inspector Armbruster 2002
H. zebra Isbrücker and Nijssen, 1991

DIAGNOSIS

Hypancistrus can be diagnosed by two characteristics unique within the Loricariidae: a wide separation between the metapterygoid and the lateral ethmoid and the presence of a sharply angled adductor palatini crest of the hyomandibula. In addition, Hypancistrus has a loss of the lateral wall of the metapterygoid channel. See Discussion for further information on these characters.

DESCRIPTION

Hypancistrus are small- to medium-sized fishes that can be recognized from the very similar Peckoltia and Hemiancistrus by having larger dentary teeth than premaxillary teeth. Color is typically some combination of dark browb to black with white, ranging from stripes to spots to squiggles.

Breeding males have larger odontodes on the pectoral fin spines and on the cheek (Isbrücker and Nijssen, 1991). In some species, breeding males also have hypertrophied odontodes on the lateral plates like Peckoltia.

COMPARISONS

Hypancistrus can be distinguished from all other ancistrines except Exastilithoxus, Leporacanthicus, Lithoxus, Megalancistrus, Panaque, Parancistrus, most Peckoltia, Pseudacanthicus, and Spectracanthicus based on the presence of highly angled jaws (dentaries forming an angle with one another of less than 90 degrees versus greater than 90 degrees). Hypancistrus can be separated from Exastilithoxus by the lack of fimbriae on the lower lip, from Lithoxus by not being dorsoventrally flattened, from Exastilithoxus and Lithoxus by having five rows of plates (versus three) on the caudal peduncle, from Leporacanthicus by lacking fimbriae on the upper jaw (vs. small, thin, fleshy projections on the upper jaw), from Leporacanthicus, Megalancistrus, and Pseudacanthicus by lacking highly keeled lateral plates (vs. odontodes of central row of each plate hypertrophied and forming a keels on the plates), from Parancistrus, and Spectracanthicus by having the dorsal-fin membrane well separated from the adipose-fin spine (vs. contacting the adipose-fin spine), from Parancistrus by lacking fleshy tentacles in the flesh around the dorsal fin and by having the abdomen only partially plated (vs. fully plated), from Panaque by lacking spoon-shaped teeth (vs. medial tooth cusp expanded into a spoon-shaped structure), from Peckoltia by having few plates on the abdomen (vs. almost completely plated), from Scobinancistrus by having the teeth pointed with both cusps almost equal in length in medial teeth (vs. elongate spatulate teeth with the medial lobe much longer than the lateral lobe), and from Spectracanthicus by having hypertrophied odontodes set on evertible cheek plates (vs. hypertrophied cheek odontodes and evertible cheek plates absent).

DISTRIBUTION

Now known from the Rio Negro, upper Rio Orinoco, and southern drainages of the Amazon.

Key to the Species of Hypancistrus

1a. Color pattern consisting of vertical stripes, dorsal saddles, or vermiculations.............2

1b. Color pattern consisting of white, pink, or gold spots on a dark background.............4

2a. Body base color white or cream with dark oblique stripes at least through posterior insertion of dorsal fin; patch of black pigment in the shape of an E on the snout with the central branch of the E located mid-dorsally, the top and bottom branches located just lateral to the nares, the three branches extending anteriorly, and the main stem of the E running transversely centered on the nares........... 3

2b. Body base color dark with light colored stripes or vermiculations occasionally coalescing to form bands; patch of black pigment in the shape of an E on the snout either weakly formed or absent............. H. debilittera

3a. Body with usually just one oblique stripe, stripes ending behind dorsal fin, saddles present; background color white or light cream........... H. furunculus

3b. Body with oblique stripes continuing from just behind head through caudal fin, saddles absent; background color white............ H. zebra

4a. Dorsal fin does not reach adipose fin when adpressed. Spots smaller on head than on body; spots on upper lobe of caudal fin combine to form bands; mid-ventral plates 24............ H. inspector

4b. Dorsal fin reaches adipose fin when adpressed. Spots the same size on head and body or absent; spots on upper lobe of caudal fin all free and do not form bands, mid-ventral plates usually 22–23 (rarely 24)............ 5

5a. Spots ranging in diameter from that of nasal aperture to that of interradial distance of the dorsal fin; in life, spots are white to pink............ H. contradens

5b. Spots smaller in diameter than nasal aperture or absent; in life, spots are gold...........H. lunaorum

LITERATURE CITED

Armbruster, J. W. 2002. Hypancistrus inspector , a new species of suckermouth armored catfish (Loricariidae: Ancistrinae). Copeia 2002:86-92.

Armbruster, J.W., N.K. Lujan, and D.C. Taphorn. 2007. Four new species of Hypancistrus from southern Venezuela (Siluriformes: Loricariidae). Copeia 2007:62-79.

Isbrücker, I.J.H. and H. Nijssen. 1991. Hypancistrus zebra, a new genus and species of uniquely pigmented ancistrine loricariid fish from the Rio Xingu, Brazil (Pisces: Siluriformes: Loricariidae). Ichthyol. Explor. Freshwaters 1:345-350.

HYPANCISTRUS DIVERSITY - UNDESCRIBED SPECIES