Pseudorinelepis genibarbis, Photo by K.S. Cummings
Pseudorinelepis Bleeker 1862: 3, type species: Rhinelepis
genibarbis Valenciennes 1840.
Canthopomus Eigenmann 1910: 404, 407, type species: Rhinelepis genibarbis Valenciennes 1840.
Monistiancistrus Fowler 1939: 236-237, Fig. 26-27, type species: Monistiancistrus carachama Fowler 1939.
MZUSP 52897 (1), Brazil, Amazonas, lago Castro do Rio Purus.
OTHER SPECIMENS EXAMINED
Brazil, Amazonas: FMNH 95569 (1), FMNH 95570 (1cs), MZUSP 6339 (4, 1cs),
and ZMA 107.858 (3), same data as neotype. Brazil, Rondônia,
ZMA 119.401 (1), small pool on Rio Jamari near confluence with Rio Madeira
just below Samuel Hydroelectric. Brazil, Roraima: ZMA 120.102 (1),
Rio Branco, Marará, floodplain lake (Lago Central). Peru,
Loreto: BMNH 18035 (1), Cashiboya; CAS 42325 (1), Quebrada Yaguas Yacu
near Pebas; CAS 58801 (1), Iquitos; IIAP 114 (6), Río Samiria (Caño
Ungurahui); IIAP uncataloged (2), Tacshacocha, Río Samiria- Río
Marañon drainage; INHS 36938 (5, 1cs), Río Amazonas, at Pueblo
Gallito; INHS 36941 (1), Felipe Cocha (Río Itaya), 12 km S Iquitos
on road to Quistococha near the community of 29 Enero 1995; INHS 39730
(5, 1cs), Ushpa and Moena Caños, Río Itaya - Río Amazonas
drainage, 1.73 miles NNE Iquitos. Peru, Ucayali: ZMA 107.867 (1),
Coronel Portillo Prov., Río Ucayali basin, Cashiba Cocha.
Peru, department unknown: IIAP uncataloged (1), Cocha Vainilla, Supay -
Río Ucayali drainage.
Pseudorinelepis and, hence, P. genibarbis was diagnosed
by the following synapomorphies by Armbruster (1998a): an enlarged posterior
shelf of the fourth epibranchial; a well-developed lateral ridge on the
quadrate; a wide, flat parasphenoid; well-developed ridges on the pterotic-supracleithrum
(taller than in other loricariids); a wide ventrolateral strut of the coracoid
that is wholly exposed (supporting odontodes directly); passage of the
arrector ventralis muscle of the pectoral girdle through a channel; and
elongate, nonevertible cheek odontodes. Of these, only the wide,
flat parasphenoid is unique among loricariids to Pseudorinelepis. genibarbis
Largest specimen examined male, 356.2 mm SL (ZMA 120.102). A large,
bulky loricariid with strongly keeled lateral plates that have well-developed
ridges of bone and odontodes above and below the keels. Head relatively
short when compared to the related Rhinelepis (head depth to head
length ratio 59.1-78.0% vs. 47.0-59.0%; Armbruster & Page, 1997).
Pectoral fins relatively short (spine when folded ventral to pelvic fin
extending from just prior to pelvic spine to slightly overlapping it).
In large juveniles and adults, abdomen completely encased in plates as
is small area just above pelvic fins. Lateral plates thick.
Adipose fin and raised, median pre-adipose plate absent. Caudal peduncle
roughly circular in cross-section. Teeth bifid; long and thin with
small cusps. Tooth number increases with body size (Fig. 1).
Small papilla present in middle of buccal cavity. As in other members
of Rhinelepis group, anus close to anal fin, separated only by small plate;
eye simple, lacking dorsal flap of iris that makes eye appear bilobed in
most other loricariids. Dorsal fin II 7 (one specimen has additional,
incomplete ray between posterior two, complete rays), pectoral fin I 6,
pelvic fin I 5, anal fin I 5, caudal fin I 14 I. Lateral line plates
23-26 (25), plates under base of dorsal fin 6-7 (7), plates in depressed
dorsal fin 11-14 (12), postdorsal plates 12-15 (14), postanal plates 8-12
(12), teeth 23-62 per jaw ramus.
Color patterns are variable and Pseudorinelepis genibarbis can change color to match substrate. Most specimens preserved in alcohol are brown to charcoal gray with few if any spots (generally restricted to dorsal-fin membranes). In life, Pseudorinelepis may be completely dark brown to black; mottled with tan to dark brown background and black streaks; or light tan with large, sparse spots located at base of lateral plates, on fin membranes, and on abdomen. Armbruster & Page (1997) suggest that breeding males develop orange coloration along cheek margin and dorsal- and caudal-fin spines, but the orange coloration may be restricted to specimens from the Rio Branco.
Sexual dimorphism. Males have longer odontodes on the cheek that
are more dense and numerous than in females; males may also have orange
on the cheeks and dorsal- and caudal-fin spines.
Pseudorinelepis genibarbis can be distinguished from all other hypostomines and ancistrines by a combination of the absence of an adipose fin, a simple eye without a dorsal flap of the iris (vs. dorsal flap of iris present making the eye appear bilobed); 5 branched anal-fin rays (vs. 4 in Hypostomus and Pterygoplichthys); a single medium-sized plate posterior to the pterotic-supracleithrum (vs. many small plates or no plates in some loricariids); a patch of non-evertible, elongate odontodes on the cheek, well-developed ridges on the pterotic-supracleithrum (vs. ridges not as well-developed); and well-keeled lateral plates. See also Armbruster & Page (1997).
Pseudorinelepis genibarbis differs from all other members of
the Rhinelepis group by the presence of tall ridges on the pterotic-supracleithrum,
keeled lateral plates, and a coracoid strut that is completely exposed.
In addition, Pseudorinelepis can be distinguished from Pogonopoma
by the lack of an adipose fin, a completely plated abdomen, and a larger
head depth/SL ratio (20.0-26.0% vs. 16.1-19.8%); from Pogonopomoides
by the presence of elongate cheek odontodes in adults, a completely plated
abdomen, and the following morphometric features: a smaller snout length/SL
ratio (13.8-17.6% vs. 17.6-19.3%), a larger thorax length/SL ratio (25.8-31.7%
vs. 18.9-23.3%), a larger head depth/SL ratio (20.0-26.0% vs. 15.5-19.0%),
and a larger cleithral width/SL ratio (27.5-32.1% vs. 23.3-27.5%); and
from Rhinelepis by the presence of elongate cheek odontodes in adults,
lack of a plate between the pterotic-supracleithrum and the exposed opercle,
small (vs. large) gill openings, and the following morphometric features:
a smaller snout length/SL ratio (13.8-17.6% vs. 21.0-24.3%), a smaller
interorbital width/SL ratio (12.4-16.6% vs. 18.2-19.4%), a larger thorax
length/SL ratio (25.8-31.7% vs. 15.1-20.7%), a larger postanal length/SL
ratio (20.6-31.0% vs. 20.3-24.1%), and a larger dorsal fin spine length/SL
ratio (23.6-34.2% vs. 18.5-22.9%). See also Armbruster (1998a).
In Iquitos, Peru, Pseudorinelepis genibarbis is often referred
to as carachama sin costilla, which means loricariid without ribs.
This refers to one of the diagnostic characters of the Rhinelepis group,
a lack of ribs beyond the enlarged rib of the sixth vertebral centrum (Armbruster,
From Brazil and Peru, in the Amazon River and its major tributaries (Rios Madeira and Negro in Brazil and Ríos Marañon, Napo, and Ucayali in Peru; see below). Based on specimens examined and personal observation, Pseudorinelepis genibarbis is typically found in small sluggish streams, floodplain lakes, and large rivers.
The question mark refers to a potentially introdcued poipulation of Rhinelepis.
Armbruster, J.W. and L.M. Page. 1997. Generic reassignments of the loricariid species Monistiancistrus carachama Fowler 1940, Plecostomus lacerta Nichols 1919, and Rhinelepis levis Pearson 1924 (Teleostei: Siluriformes). Copeia 1997:227-232.
Armbruster, J.W. 1998. Phylogenetic relationships of the suckermouth armored catfishes of the Rhinelepis group (Loricariidae: Hypostominae). Copeia 1998:620-636.
Armbruster, J.W. and M. Hardman. 1999. Redescription of Pseudorinelepis
genibarbis (Loricariidae: Hypostominae) with comments on behavior as
relates to air-holding. Ichthyological Exploration of Freshwaters 10:53-61.