Dekeyseria Rapp Py-Daniel, 1985

Dekeyseria pulcher, Photo by N.K. Lujan

Dekeyseria niveata, Photo by M.H. Sabaj


TAXA LIST
Isbrücker et al. (2001) describe Zonancistrus for D. brachyurus, D. pictus, and D. pulcher, but I see no reason to recognize this as a distinct genus given that Dekeyseria with these species included is a well diagnosed genus and color pattern is not a useful chacateristic in diagnosing genera.  I treat Zonancistrus as a synonym of Dekeyseria. The degree of color pattern difference is no greater than in other genera endemic to the Rio Negro and upper Rio Orinoco like Hypancistrus and Pseudolithoxus. The following is an excerpt from Armbruster (1997).
SYNONYMS

Zonancistrus Isbrücker, 2001



SPECIES


DIAGNOSIS

Dekeyseria is not diagnosed by any unique characteristic.  Characteristics considered synapomorphic for Dekeyseria are: loss of the accessory process on the first epibranchial, elongated first hypobranchials, a medially placed interohyal, loss of the connection between the hyomandibula and the quadrate mesially, tall walls of the pterygoid channel, a short anterior process of the metapterygoid, reversal to a maxilla shorter than the palatine, loss of an overhang on the metapterygoid condyle of the lateral ethmoid, lower hypurals much longer than the upper hypurals, placement of the first neural arch in front of the first dorsal fin pterygiophore, exposure of the first anal fin pterygiophore, the abductor fossa of the pectoral girdle nearly flat anteromesially, the cleithrum shaped like a trapezoid anteriorly, straight anterolateral processes of the pelvic basipterygium, and rows of long, sharp odontodes forming keels on the lateral plates.

Breeding males develop elongated odontodes along the snout margin anterior to the evertible cheek odontodes and on the pectoral fin rays. The brown species appear to have a greater development of the snout odontodes and the barred species a greater development of the pectoral fin spine odontodes.



DESCRIPTION

Dekeyseria is an unusual group of fishes that appear similar to Lasiancistrus. Color pattern is variable with some species brown with some mottling in the fins, and others with a bold pattern of brown bars on a tan background.  In brown species, the abdomen is slightly lighter than the sides.  In barred species, the head has large tan spots, the spots becoming larger posteriorly until the bars form as separate entities.  There are about eight bars, the first before the dorsal fin, the second just posterior to the origin of the dorsal fin, the third at the posterior of the dorsal fin, the fourth just before the adipose fin, the fifth under the adipose fin and including the adipose spine, and the remainder on the caudal fin.  The first three bars are branched with the bars appearing to fuse along the sides.  The preadipose band partially circles the caudal peduncle and is contiguous with a brown marking on the anal fin, and the adipose band circles the caudal peduncle.  Fins with wide bands; abdomen white and naked.  Three predorsal plates.  Three rows of plates on the caudal peduncle.  The species are flattened more than typical Ancistrini, and the lateral plates have median rows of long, sharp odontodes forming keels.  Odontodes form well-developed rows above and below the keel rows in all individuals.  Tentacules are associated with odontodes on the pectoral fin spine and snout, but are shorter than the supporting odontodes.

The odontodes along the snout and on the pectoral fin spine are larger in males.  In some species, the cheek odontodes are extremely long.



COMPARISONS

Dekeyseria differs from all other Ancistrini except Acanthicus, Leporacanthicus, Megalancistrus, and Pseudacanthicus (the Acanthicus group) by the presence of the sharp odontode keels.  In Dekeyseria, however, there are rows of odontodes above and below the keels, whereas in the Acanthicus group there are usually few odontodes above or below the keels in all but the largest adults (greater than 200 mm ) and no complete rows.  Also, there are only seven dorsal fin rays in Dekeyseria (vs. eight or more), three rows of plates on the caudal peduncle (vs. five), and no plates on the abdomen.  Dekeyseria differs from Pterygoplicthini by lacking plates on the abdomen.  Dekeyseria appears most similar to Lasiancistrus but lacks whiskerlike odontodes on the cheek and tentacules longer than the supporting odontodes on the snout of breeding males.



ECOLOGY

Reported as an air-breather (Val and Almeida-Val, 1993).



DISTRIBUTION

Known from the Rio Negro, floodplain lakes of the Amazon, and upper Orinoco.



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.

Isbrücker, I. J. H., I. Seidel, J. P. Michels, E. Schraml & A. Werner. 2001. Diagnose 14 neuer Gattungen der Familie Loricariidae Rafinesque, 1815 (Teleostei, Ostariophysi). Pp. 17-24 in R. Stawikowski, ed. "Sonderheft Harnischwelse 2". Datz 1.1.2002.

Val, A.L. and V.M.F. de Almeida-Val. 1995. Fishes of the Amazon and their environment.  Zoophysiology Vol. 32.  Springer-Verlag, Berlin. 224 pp.


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