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Photo by K.S. Cummings
Hemiancistrus annectens group
Photo by K.S. Cummings
Photo by J.W. Armbruster showing the evertible cheek plates and associated hypertrophied odontodes of Hemiancistrus aspidolepis of the H. annectens group.
The Pterygoplichthys group is diagnosed by one unique characteristic: the presence of an enlarged stomach that is attached to the dorsal abdominal wall by a connective tissue sheet (Armbruster, 1998c, below, photo by K.S. Cummings).
A = Artery
CTN = Connective tissue net
ES = Esophagus
INT = Intestine
PY = pylorus
S = Stomach
V = vein
Differs from the Rhinelepini and Hypostomus by having evertible cheek plates. It is difficult to separate the species as a whole from Ancistrini as a whole except by examining the stomach for the presence of a connective tissue sheet (above). Pterygoplichthys differs
from all Ancistrini except Acanthicus and Chaetostoma by
having more than seven dorsal-fin rays; from Chaetostoma by having
plates on the abdomen; from the subgenus Acanthicus by having an
adipose fin (vs. adipose fin absent) and by having the pterotic-supracleithrum
taller than long (vs. longer than tall); and from the subgenera Leporacanthicus,
Megalancistrus, and Pseudacanthicus by having more than ten
teeth per jaw ramus. The Hemiancistrus annectens group differs
from Acanthicus and Chaetostoma by having seven dorsal fin
rays (vs. 8+); from Ancistrus, Baryancistrus, Chaetostoma , Dekeyseria,
Lasiancistrus, Acanthicus (Leporacanthicus), the Lithoxus
group, Hemiancistrus megacephalus, Neblinichthys, Pseudancistrus,
and Spectracanthicus by having plates on the abdomen (vs. abdomen
naked); from Hypancistrus, Panaque, Parancistrus, and most Peckoltia
by having the dentaries meet at an angle greater than 80° (vs. less
than or equal to 80°); from all but Acanthicus, Dekeyseria, Chaetostoma
platycephalus, Hemiancistrus landoni, Panaque, and Peckoltia
by having keeled lateral plates (vs. unkeeled); and from Hemiancistrus
landoni by having less than ten hypertrophied cheek odontodes (vs.
Known from nearly the entire range of loricariids except for the Guianas
and coastal streams in southeastern Brazil.
Armbruster, J.W. 1998. Modifications of the digestive tract for holding
air in loricariid and scoloplacid catfishes. Copeia 1998:663-675.
Armbruster, J. W. 2004. Phylogenetic relationships of the suckermouth armoured catfishes (Loricariidae) with emphasis on the Hypostominae and the Ancistrinae. Zoological Journal of the Linnean Society 141:1-80.