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163
Ichthyol. Explor. Freshwaters,
Vol. 18, No. 2, pp. 163-174,
6 figs.,
I tab.,
June
2007
@ 2007 by Verlag Dr. Friedrich Pfeil, Miinchen, Germany
- ISSN
0935-9902
Two new species of Pseudflncistrus
from southern Venezuela
(
Siluriforrnes: Loricariidae)
Nathan K. Lujan*, Jonathan
W. Armbruster* and Mark H. Sabaj**
Two new species of Pseudancistrus
are described from the upper Rio Orinoco and Rio Negro in Southern Vene-
zuela. Pseudancistrus pectegenitor was collected
in the main channel of the Rio Orinoco near the mouth of the Rio
Ventuari and in the middle reaches of the Rio Casiquiare. It differs from congeners by having 10-11 dorsal-fin
rays (vs. seven), adpressed cheek odontodes
reaching
to three or more plates
beyond the opercle in adults (vs.
maximally to rear edge of the opercle), plates of ventral row of caudal peduncle with dorsal laminae strongly
concave, accentuating the medial keel of the ventral plate row (shared
with P. sidereus),
and large oral papillae
internal to the dentary tooth cup (shared
wilh P. coquenani, P, orinoco,
and P. yekuana).
Pseudancistrus yekuana is
known only from the type locality, immediately upstream of Salto
Tencua
in the upper Rio Ventuari. It differs
from congeners by having large oral papillae internal to the dentary tooth cup (shared
with P. coquenani, P.
ori-
noco, and P. pectegenitor),lower lip reaching to middle of pectoral girdle (vs. to anterior edge of pectoral
girdle),
pectoral-fin spine maximally reaching posterior base of the pelvic-fin spine
when adpressed ventral to the pelvic
fin (vs. at least halfway through pelvic-fin insertion)
and by several morphometric differences.
Se describen dos especies
nuevas
del g6nerc Pseudancrsfrls
(familia Loricariidae)
de la parte alta del Rio Orinoco
y del Rio Negro en el sur de Venezuela. Pseudancistrus pectegenitor fue colectado en el canal principal del Rio
Orinoco cerca de la boca del Rio Ventuari y en los tramos medios del Rio Casiquiare. Esta especie difiere de sus
cong6neres por presentar 10-11 radios en la altea dorsal (vs.
siete),
odontodos
en la mejilla alcanzando tres
o mds
placas por detr6s del op€rculo en adultos cuando se encuentran en posici6n retractada
(vs.
no extendi6ndose mas
alld del borde posterior del op€rculo), placas de la fila ventral del pedrinculo caudal con liiminas dorsales que
presentan una profunda concavidad y acent(an la quilla medial de la fila de placas ventral (condici6n
compar-
tida con P.sidereus), papilas orales de gran tamafro situadas en posici6n interna a la caja dentaria (condici6n
compartida con
P. coquenani,
P . orinoco, and P . yekuana). Pseudancistrus yekuana
se
conoce rinicamente de su loca-
lidad tipo, en las inmediaciones
superiores al Salto
Tencua
en la parte alta del Rio Ventuari. Esta especie difiere
de sus cong6neres por presentar papilas orales
de gran tamafro
situadas en posici6n interna a la caja dentaria
(condici6n
compartida con P. coquenani, P. orinoco, and P. pectegenifor), labio inferior extendi6ndose hasta la parte
media de la cintura pectoral (vs. alcanzando rinicamente
el borde anterior de la cintura pectoral),
espina de la
aleta pectoral alcanzando a lo sumo el borde posterior de la base de Ia espina p6lvica cuando se encuentra en
posici6n extendida hacia la aleta p€lvica (vs. alcanzando por lo menos hasta la parte media del inserci6n de la
aleta p6lvica) y por varias
diferencias
morfom€tricas.
Department
of Biological
Sciences,
Auburn University,33l Funchess, Auburn, AL 36&{9, USA.
E-mail: NKL: luiannk@auburn.edu,
JWA: armbrjw@auburn.edu
Academy of Natural Sciences, 1900 Beniamin Franklin Parkway, Philadelphia,
PA 19103,
USA.
E-mail: sabaj@achatsci.org
Ichthyol. Explor. Freshwaters, Vol. 18, No.2
164
Introduction
The Proterozoic outcrops in the upper Orinoco
are an incredibly species-rich and historically
under-studied habitat for loricariid catfishes,
as
evidenced
by this and
several
other recent species
descriptions
(for example, Werneke et a1.,2005a;
Werneke et al., 2005b; Armbruster, 2005;
Arm-
bruster et a1.,2007). Recent fieldwork in Amazo-
nas, Venezuela by AUM, ANSP, and MCNG has
yielded several hundred lots of loricariids col-
lected largely from rocky habitats in the upper
Rio Orinoco, upper Rio Negro, and
many tributar-
ies thereof.
Included in these are at least two new
species of.
Pseudancisfrus with enlarged dentary
papillae.
Armbruster (2004a-b)
redescribed and diag-
nosed the genus
Pseudancistrus and treated Lithox-
ancistrus
and Guyanancrsf
rus as
junior
synonyms.
Armbruster (2004b)
listed 14 nominal species in
Pseudancistrus
of which 12 are
currently
consid-
ered
valid. Of these, two species,
P. coquenani
and
P. orinocohave
large
oral papillae
on each dentary
just internal to the tooth cup (Fig.
1). This char-
acter
was used by Isbnicker et al.
(1988)
to propose
the new genusLithoxancistrus for their new species
L. orinoco; however, dentary papillae also occur
in Chaetostoma
and some Cordylancistrus
(Arm-
bruster, 2004a-b;
fWA, pers. obs.). The purpose
of this paper is to describe
two new species of
Pseudancistrus that share with P. coquenani and
P. orinoco the presence of dentary papillae. One
of these species,
P. pectegenitor, is large with an
increased
number of dorsal-fin rays, making it
very easy to diagnose
from other Pseudancistrus
despite a sample size of only four adults. The
second species,
P.yekuana, is small and very
similar to P. orinoco.In fact, P. yekuana may not
have
been easily
diagnosed from P. orinoco if they
were not sympatric.
Methods
Counts and measurements follow Armbruster
(2003).
Character numbers and states are from
Armbruster (2004b)
and are presented in paren-
theses. One specimen of each species
was cleared
and stained
(cs.)
for examination
of bone and
cartilage
using the methods of Taylor & Van Dyke
(1985).
Institutional abbreviations are as
in Levi-
ton et al. (1985).
Dentary papillae are defined as
a simple papilla or clusters of papillae located
proximally along each dentary, internal to the
tooth cup (Fig. 1). These papillae vary within
individuals in those
species that have
them, rang-
ing from a single large papilla to one to three
clusters of smaller papillae. Comparative speci-
mens of other loricariids examined are listed in
Armbruster (2004a-b)
and a list of members of
Pseudancistrus with dentary
papillae
is below.
A
principal components
analysis for the morpho-
metric data was performed using a covariate
matrix and
log-transformed
measurements in JMP
(Vers.
5.01a, SAS Institute,2002). The data for
P. coquenani and P. orinoco were combined in the
PCA because there are no discernable morpho-
metric differences between the two species.
Pseudancistrus pectegenitor, new species
(Figs.
2-3)
Holotype. MCNG 54797
(formerly AUM42130),
241.6 mm SL; Venezuela: Amazonas: Rio Casiq-
uiare,
bedrock in stream,73
km NE of San Carlos
de Rio Negro (2o21'09"N
66'34'31"W); 9 March
2005, N. K. Lujan, D. C. Werneke, M. H. Sabaj,
M. Arce,
R. Betancur & T. E. Wesley.
Paratypes. AUII{ 42202,227.0 mm SL; Venezuela:
Amazonas: Rio Casiquiare,
153 km NE of San
Carlos
de Rio Negro
(247'56"
N 66"00'23"W);24
March 2005, N. K. Lujan et al.
- AUM 43'192
(cs.),
173.6 mm SL;
Venezuela: Amazonas: Rio
Orinoco,
beach and bedrock outcropping, 50
km E of San
Fernando de Atabapo.
- ANSP 182801
(formerly
4UM421.8'D,225.1 mm SL;
Venezuela: Amazonas:
Rio Orinoco, Punto de Maraya, Isla Maraya,
80.8 km W of San Fernando de Atabapo
(4'01'23"
N 56'58'19" W); 31 March 2005, N. K. Luian et
al.
Diagnosis. Pseudancistrus pectegenitor
can be
diagnosed
from all other
Ps
eudancistrusby having
10-11 dorsal-fin rays
(vs.
7) and adpressed
cheek
odontodes reaching to three or more plates be-
yond the opercle
in adults (vs.
maximally to rear
edge of opercle);
from all other described Pseu-
dancistrus except P. sidereus by having the plates
of the ventral row of the caudal peduncle with
dorsal laminae strongly concave, accentuating
the medial keel of the ventral plate row (vs.
ven-
tral plate
row slightly convex; Armbruster,2005);
and from all Pseudancisfrus
except P. coquenani,
P.orinoco, and P. yekuana by having large oral
Luian et al.: Twonew Pseudancistrus
Fig. 1. Mouth of; a, Pseudancistrus yekuana;
and b P. pectegenitor.
Arrows point to dentary papillae.
papillae proximally on each dentary just internal
to the tooth cup (vs.
papillae
absent;
Fig. l). Pseud-
ancistrus pectegenitor
can be further diagnosed
from P. coquenani, P.orinoco,
and P. yekuana
by
having a larger pectoral-fin
spine
(38.342.2
Vo SL
vs.22.0-31,.4)
and from P. coquenani and P. orino-
co by having a smaller head-dorsal length (5.6-
6.8 Vo SL
vs.
8.0-12.2).
Description. Morphometrics presented in Ta-
ble 1. Meristics
based on four individuals. Large
loricariids, largest
specimen 241.5 mm SL. Body
squat with large, dorsoventrally depressed head
and stout trunk. Snout sloped at -30o angle to
orbit; dorsal profile slightly arched from orbit to
posterior insertion of adipose fin with depth at
adipose
fin shallower than depth at orbit; body
depth greatest in nuchal region. Eyes set far pos-
teriorly on head with orbits oriented at -45o from
sagittal plane. Ventral profile angled slightly
downward from snout to coracoid, then flat to
caudal fin.
Anterior margins of snout with small to me-
dium-sized hypertrophied odontodes. Evertible
cheek
plates with highly hypertrophied, distally
hooked
odontodes
(range
M-57), longest extend-
ing beyond posterior edge of pectoral fin. Head
contours smooth with slightly raised supraorbital
crest
from anterolateral corner of nares to poste-
rior edge of pterotic. Lateral
surfaces of supraor-
bital crest covered with odontodes slightly en-
larged relative to those on surrounding plates.
Nuchal region forming a broad hump slightly
raised above supraoccipital
and dorsal-fin base.
Mouth large with broad, straight jaws nearly
Ichthyol. Explor. Freshwaters,
Vol. 18, No.2
165
as wide as
head. Tooth cups of upper jaw slight-
ly wider than those of lower jaw. Premaxillary
teeth 119-164
(median
131);
dentary teeth 126-134
(median 128).
Teeth villiform and bicuspid with
medial cusp larger than lateral cusp. Worn teeth
with cusps approachingequal length. Lateral edge
of oral disk extending slightly beyond lateral
margins of head. Maxillary barbel short and oc-
casionally bifurcated distally. Ventral surface of
lips papillose. Papillae increasing in size and
decreasing in density from labial rictus (smallest
and most dense), to regions
proximal and poste-
rior to dentary tooth cups (intermediate), to
larger
and less-densely
spaced papillae restricted
to band along middle of lower lip; posteroventral
edge of lower lip devoid of papillae. Dentary
papillae present. Buccal papilla present, with a
long stalk-like base.
Dorsal fin II,10;
dorsal-fin spinelet short and
V-shaped;
dorsal-fin lock functional. Dorsal fin
large, as high or higher than body depth. Ante-
rior dorsal-fin rays longer than dorsal-fin spine
and decreasing in length posteriorly, forming a
gentle
arc towards adipose
spine. Pectoral fin I,6;
pectoral
spine extending
beyond posterior inser-
tion of pelvic fin when adpressed. Pectoral-fin
spine stout with odontodes increasing in size and
density distally. Distal odontodes very hypertro-
phied, intermediate in size to those of evertible
cheek plates and those of snout. Anterior pectoral-
fin rays as
long as pectoral-fin spine, decreasing
to less than half of length of spine posteriorly.
Pelvic fin I,5; pelvic-fin spine stout, reaching
end
of base of anal fin when adpressed;
anterior pel-
vic-fin rays as
long as or longer than pectoral-fin
Fig. 2. Pseudancistrus
pectegenitor,
AUM 42202, 227 .0
mm SL; Venezuela:
Rio Casiquiare; freshly dead.
Photo by
N. K. Luian.
spine with posterior margin of fin curving out
beyond posterior tip of spine. Anal fin I,5; ante-
rior anal-fin rays slightly longer
than unbranched
anal-fin ray, posterior
anal-fin rays
slightly short-
er than unbranched anal-fin ray. First anal-fin
pterygiophore not exposed to form a plateJike
structure. Adipose-fin
spine straight with adipose
membrane
not extending beyond posterior
extent
of spine. Caudal fin 1,1.4,I;
caudal-fin spines
longer than caudal-fin rays. Dorsal and ventral
procurrent caudal-fin rays four to five. Posterior
caudal-fin margin straight. Rays
of all fins sup-
porting small odontodes.
Body broad at base and compact in length,
with short and stout caudal peduncle. Lateral
body plates in median series 25. Ventral plates
forming right angle on caudal peduncle with
dorsal lamina of plates concave, accentuating
strong rounded keel along lower portion of cau-
dal peduncle. Plates in middorsal row weakly
arched submedially forming low ridge from
cleithrum to posterior
insertion
of pelvic fin. Five
rows of plates on caudal peduncle. Abdomen
naked.
Color. Alcohol preserved adults with gray-tan
to charcoal
ground color on head and plated re-
gions of body. Unplated ventral surface
of snout
and outer surface
of upper lip gray brown; un-
plated breast and abdominal region lighter, pale
dusky white and without distinct markings.
Papillated
surfaces
of ventral oral disk pale white
with dusky posterior margin (darkest
near base
of maxillary barbel).
Lighter specimens with faint
pattern of small light spots and fine vermicula-
tions on head
(particularly pterotic region),
body
plates, and skin along dorsal-fin insertion; and
gray-tan body plates
outlined with darker gray-
brown skin. Dorsal-,
adipose-,
caudal- and anal-
fin spines, rays and membranes
nearly uniform
gray
brown, without conspicuous
pattern. Paired
fins similar or with faint pattem of small light
spots and vermiculations
on rays
and to a slight-
ly lesser
degree
on membranes.
Hypertrophied
odontodes orange to straw colored. Small pre-
served
juveniles
(< 13 mm SL)
with body more or
less uniformly brown except ventral surface from
oral disk to vent white; fins darker brown with
distal margins
and/or tips hyaline
(depigmented).
Luian et al.: Two new Pseudancistrus
767
Fig.3. Pseudancistrus
pectegenlfor,
holotype, MCNG 54797, 241.6 mm SL; Venezuela:
Rio Casiquiare. Photos
by
M. H. Sabaj.
lchthyol.
Explor. Freshwaters,
Vol. 18, No.
2
768
In live adults ground color dull olive to charcoal
with lighter spots and vermiculations yellowish
to tan (Fig.2).
Sexual dimorphism. Darwin (1882)
used Psezd-
ancistrus
barbatus to illustrate an example of
sexual dimorphism in which males are adorned
with highly hypertrophied odontodes
and females
are not; however, both sexes
in P.barbatus and
other species of. Pseudancistrus are more recently
known to exhibit such
armament although males
may be better adorned than females
(Armbruster
& Provenzano,2000).
The only specimen ofP. pec-
tegenitor collected in an ecological context allow-
ing reasonable
deduction of sex, a presumably
adult male
([UM42202,227.0mm SL) collected
while guarding young in a nest,
exhibited extreme
hypertrophy of odontodes
on the evertible cheek
plates and, to a lesser
extent, on the
pectoral spines
and snout. A single immature P. pectegenitor in-
Table 1. Selected morphometrics ol Pseudancistrus
pectegeiltor
and P.
yekuana.
Landmarks represent the two
landmarks the measurement is between
(see
Armbruster, 2003).
landmarks ranSe
P. pectegenitor
n=4 P. yekuana
n=3
range mean SDSD
Standard
length (mm)
In percents
of standard length
Predorsal length
Head length
Head-dorsal length
Cleithral width
Head-pectoral length
Thorax length
Pectoral-spine length
Abdominal length
Pelvic-spine length
Postanal length
Anal-fin spine length
Dorsal-pectoral depth
Dorsal spine length
Dorsal-pelvic depth
Dorsal-fin base length
Dorsal-adipose depth
Adipose-spine length
Adipose-upper caudal depth
Caudal peduncle
depth
Adipose-lower caudal depth
Adipose-anal
depth
Dorsal-anal depth
Pelvic-dorsal depth
In percents
of head length
Head-eye length
Orbit diameter
Snout length
Internares width
Interorbital width
Head depth
Mouth length
Mouth width
Barbel length
Dentary tooth cup length
Premax. tooth cup length
1,-20
1-10
1-7
7-70
8-9
1-12
1,2-'t3
1.2-29
13-1,4
13-30
14-15
1,4-31,
1,0-1,2
10-11
10-13
10-16
tG17
17-'t8
1,7-1,9
15-19
1,5-17
14-'.17
1,4-16
13-16
5-7
+5
74
2-3
5-6
7-1,2
t-24
21-22
22-23
25-26
27-28
173.6-241,.6
4.0-M.2
35.9-38.1
5.6-6.8
29.2-34.1.
30.6-32.9
22.9-25.1
38.342.2
22.3-24.7
23.1-27.4
27.8-37.5
't1,.2-13.3
24.6-26.4
28.8-35.2
22.6-25.5
34.0-38.0
8.8-11.1
5.6-7.8
8.9-10.5
1,2.1-13.6
1,7.4-1,8.5
18.9-20.5
1,4.7-16.4
30.0-34.8
25.3-29.9
1,4.6-1,6.0
65.7-69.7
1,7.0-1,2.2
33.041,.7
62.8-64.4
49.4-58.4
62.3-75.9
9.3-10.9
23.0-27.2
21,.5-26.5
21,6.8 29.7
43.5 1.0
37.0 0.9
6.2 0.6
31,.4 2.1
31.9 1.2
24.0 1.0
40.1 1,.9
23.5 1.0
24.7 2.0
29.5 1.5
1,2.2 1.0
25.7 0.8
32.0 4.5
23.9 1.5
35.6 1.8
r0.2 1.0
6.6 1.1
9.6 0.8
1,2.7 0.7
L7.8 0.5
19.8 0.7
15.5 0.8
32.3 2.5
27.5 1,.9
1s.0 0.6
58.0 7.4
77.4 0.5
36.8 3.6
63.4 0.7
52.3 4.1,
70.3 6.2
10.1 0.8
24.8 1.8
24.9 2.3
32.742.7 38.6 5.2
49.1-50.1 49.6 0.5
39.943.8 42.4 2.1,
6.0-8.0 6.9 1.0
28.6-30.4 29.3 1.0
38.3-38.9 38.5 0.3
22.8-24.5 239 0.9
22.0-24.6 22.9 1.5
17.2-22.7 79.4 2.9
2'1,.9-23.6 22.6 0.9
28.2-30.0 29.2 0.9
7.0-9.6 8.4 1.3
25.1-27.4 26.4 1.2
20.8-22.9 22.2 1,.2
1,9.9-20.8 20.5 0.5
21,.5-22.2 21,.8 0.3
'1,0.2-1,2.1,
1,1,.3 1.0
7.8-9.5 8.9 0.9
15.0-15.5 15.8 0.8
10.0-11.6 10.9 0.8
19.9-22.7 2'r.5 1.s
17.0-17.7 17.3 0.4
74.0-'t4.7 14.3 0.4
20.9-22.8 22.2 1.1
24.6-3',r.1 28.4 3.4
13.1-13.8 13.4 0.4
68.6-74.0 70.8 2.8
9.1-10.2 9.6 0.6
39.0-40.1 39.7 0.6
54.0-56.9 55.5 1,.4
70.5-77.2 73.8 3.4
73.3-78.0 75.6 2.4
5.4-9.7 8.1 2.3
24.9-37.3 28.7 3.4
27.0-28.3 27.8 0.7
Luian et al.: Two new Pseudancisttus
r69
dividual (AUM 43192, cs.,'173.5 mm SL) of unde-
termined sex lacked especially hypertrophied
odontodes. Two other individuals
(ANSP
43192,
225.1; MCNG 54797,247.6mmSL) with hyper-
trophied odontodes similar to that of the male
above were also collected but their sex was not
determined.
Range. Found in the main channel of the Rio
Orinoco above Raudales Autures (near
mouth of
Rio Ventuari), and in the Rio Casiquiare, Ama-
zonas, Venezuela
(Fig.
4).
Habitat. All specimens collected from flowing
water associated with large rock outcrops in main
river channel. One specimen
collected at night
with a seine in swift shallow run over bedrock.
All others collected by hand from within rock
crevices.
Reproductive biology. In the majority of lori-
cariids for which parental
care is known, the male
is the caregiver (Evers & Seidel,
2005;
Gross &
Sargent, 1985).
One presumablyadultmale (AUM
42202, 227.0 mm SL) was collected while caring
for young in a vertical crack
in bedrock immed!
ately below the water's
surface
(Fig.2).
Crevice
spawning is common among the Hypostominae
(Suzuki
et al., 1985)
and almost universal among
the Ancistrini
(Evers
& Seidel,2005). Water level
in the Casiquiare at this locality would have re-
cently risen with the onset of the rainy season
just
a few weeks before,
when this individual likely
spawned. Seasonal spawning timed to coincide
with the onset of the rainy season
has been ob-
served in Hypostomus luetkeni in the Paraiba do
Sul
in Brazil
(Mazzoni
& Caramaschi,
1,997),but
would be in contrast to the aseasonal breeding
cycle that Winemiller (1989)
observed
for hypos-
tomines (Ancistrus
sp. and Hypostomus
argus) in
the piedmont of northern Venezuela. An incred-
ible number of juveniles
(n=485, SL<13 mm)
were collected with the father, and dozens more
from the same nest were not collected. Among
the Hypostominae,
this level of fecundity is less
than some (e.g., Rhinelepis aspera,
a broadcast
spawner from which have been recorded up to
181 200
oocytes,avg.4T 370; Agostinho, 1985),
but
more than others (e.g.
Ancistrus
sp. reported by
Sabaj
et al.,1..999, to have 20-200
offspring, and
Lithoxus
reported by Armbruster,'1998,
to have
15-17 mature oocytes in two females).
Ichthyol. Explor. Freshwaters,
Vol. 18, No. 2
Fig.4. Range
of Pseudancistrus pectegenitor
(I,!) and
P.yekuana
(O,o),
open symbols show type localities.
Base map
by M.
I. Weitzman.
Etymology. From the
Latin pecten, rrreaning
quill,
and genitor, meaning father, in reference
to the
hypertrophied odontodes
of the snout, pectoral
spine, and evertible
cheek plates,
and the
fact
that
one presumably adult male was collected
while
caring for a large brood of young. A noun in ap-
position.
Pseudancistrus
yekuana,
new species
(Fig.
s)
Holotype. MCNG 54798
(formerly AUM39473),
42.7 mmSL;Yenezuela:
Amazonas: Rio Ventuari,
above Salto Tencua,
58 km ESE
of San
Juan de
Manapiare
(5'02'52"N
65'3 6' 57"\N); 21 April 2004,
N. K. Lujan, O. Le6n, A. Luna & A. Yarumare.
Paratypes. AUM 39 473, 2, 40.5-35.0
mm SL
(1 cs.);
ANSP 182802,32.7
mm SL, same data as holotype.
Diagnosis. Pseudancistrus
yekuana
can be diag-
nosed
from allother Pseudancistrus
exceptP. coque-
nani, P.orinoco,
and P. pectegenitor
by having
dentary papillae (vs. dentary papillae absent;
Fig. 1
); from P. coquenani,
P. orinoco,
and
P. pecte-
genitor
by having the lower lip reaching to the
middle of the pectoral
girdle (vs.
to anterior edge
of the pectoral
girdle), by having the pectoral-fin
12"
63"
170
spine maximally reaching the posterior edge of
the pelvic-fin spine when adpressed
ventral to
the pelvic fin (vs.
at least halfway through pelvic
fin); and from P. pectegenitor
by having 7 dorsal-
fin rays (vs.
10-11)
and by having the evertible
cheek odontodes maximally reaching the poste-
rior end of the opercle (vs. three or more plates
behind the opercle). In addition, several measure-
ments
serve
to separate
P. yekuana f.rom P. coque-
nani, P. orinoc o,
and
P. pe c t e genit or
; however, these
ratios have little predictive power given that there
are only four specimens of P. yekuana known:
predorsal
length
(49.1-50.1
7o
SL
in P. yekuana vs.
47.5-46.0), head length (39.9-43.8
Vo
SL vs. 31.2-
38.1),
head-pectoral
distance
(38.3-38.9
VoSL
vs.
26.8-32.9),
and
mouth length
(70.5-77
.2 % HL v
s.
49.4-67.5).
Description. Morphometrics presented in Ta-
ble 1. Meristics based on four individuals. Fairly
small loricariids, largest specimen
42.7 mm SL.
Head distinctly large relative to body, with long,
spatulate snout. Small eyes
placed high and far
back on head with orbits oriented at -45o to
sagittal plane. Dorsal contour of head smooth
except for slightly elevated plateau formed by
modest supraorbital crests
and elevated, flat in-
terorbital region. All dorsal and lateral surfaces
of head plated and with small odontodes. Odon-
todes slightly larger along anterior and lateral
margins of snout, along midline of snout over
mesethmoid, and along supraorbital crest poste-
rolateral to nares. Evertible cheek odontodes
longest, numbering 11-13
(median
12).
Dorsal profile forms gentle arc from anterior
margin of snout to posterior process of supraoc-
cipital, horizontal to insertion
of dorsal-fin spine,
then ventrally sloping at shallow angle to inser-
tion of dorsal caudal-fin spine. Ventral profile of
head sloped slightly downward from snout to
coracoid such that ventral surface of large oral
disk is even with flat, horizontal ventral profile
of trunk. Median plates 22-24
(mode=24). Five
caudal peduncle
plate rows. Abdomen naked.
Mouth large with lips occupying almost entire
ventral surface of head. Maxillary barbel short
and connected along most of length to lower lip
by flap of skin. faws wide with slight angle of
tooth cups and
inward curvature of tooth arrange-
ment in ventral view. Left premaxillary teeth
50-69
(median 67). Left dentary teeth 63-71
(me-
dian 55). Dentary papillae present. Buccal pa-
pilla present, with long, stalk-like base.
Dorsal fin ll,7; dorsal-fin spinelet short and
V-shaped; dorsal-fin lock functional. First
dorsal-
fin ray slightly longer than dorsal-fin spine; re-
maining rays decreasing in length. Last
dorsal-fin
ray when
adpressed reaching insertion of adipose-
fin spine. Pectoral hn 1,6; pectoral spine maxi-
mally reaching posterior edge of pelvic-fin spine
when adpressed ventral to pelvic fin. Anterior
and ventral surface of pectoral-fin spine with
odontodes along entire length, slightly hypertro-
phied distally. Pelvic
fin I,5; first pelvic-fin ray as
long as pelvic-fin spine and remaining rays de-
creasing
in length. Anal fin I,5; first anal-fin
pterygiophore not exposed to form a plate. Adi-
pose-fin membrane
extending slightly posterior
to adipose-fin spine. CaudaI finl,1,4,l;
caudal fin
emarginate. Dorsal procurrent caudal-fin rays
five; ventral procurrent
caudal-fin
rays
four. Rays
of all fins supporting odontodes.
Color. Alcohol preserved specimens with gray-
brown ground color on head and sides,
dorsally
with faint pattern of three to four lighter, tan
saddles, the first either at the dorsal-fin origin or
beneath the middle of its insertion; posterior
ventral sides similarly with fain tan bars, some
united midlaterally with saddles
(lighter
bars and
saddles more evident in smaller specimens).
Undersurfaces
lighter,
pale tan on unplated breast
and abdomen becoming dusky with scattered
melanophores near vent and onto plated caudal
peduncle. Oral disk with papillated surfaces
pale
white and dusky posterior margin (darkest
near
base
of maxillary barbel). All fin spines and rays
with alternating wide dark and narrow light
bands (pattern most evident in dorsal fin, least
evident in pectorals); fin membranes
hyaline or
with melanophores
scattered along rays. Small
but distinct black spot present
at base of anteri-
ormost dorsal-fin membrane in largest speci-
men.
Sexual dimorphism. None observed.
Range. Known only from the Rio Ventuari im-
mediately above Salto Tencua
(Fig.
a). The rang-
es of at least four other fish species
(all unde-
scribed) are currently restricted to the Ventuari
above Salto Tencua: Lithoxus
sp., Harttia sp.,
Brachyglanis
sp., and Geophagus sp. Thus, Salto
Tencua may function as a partial faunal barrier.
The barrier does not appear to be complete be-
cause Pseudancistrus orinoco,
a species
very simi-
Luian et al.: Two new Pseudancrstrus
1,71
Fig.
s.
Sabaj.Pseudancistrus
yekuana,
holotype, MCNG 54798, 42.7
mm SL; Venezuela:
Rio Ventuari. Photos
by M. H
lar to P. yekuana,
was collected
both above and
below the falls.
Habitat. All individuals collected by cast
net
from
torrential sheet flow over bedrock in the main
channel
of the upper Ventuari.
Etymology. The species
name, yekuana,
refers
to
the Ye-kuana,
the indigenous peoples
inhabiting
the upper Rio Ventuari and other areas
of south-
ern Venezuela
and northern Brazil, whose
gener-
ous cooperation
made this research
possible.
Treated
as a noun in apposition.
Ichthyol. Explor. Freshwaters,
Vol. 18, No. 2
172
0.4
0.3
0.2
0.1
N
o0
o- -0.1
-0.2
-0.3
-0.4
Dentary tooth cup L. Headdorsal D.
Plemaxillary tooth cup L. Dorsal-adioose
D
P. pectegenitor
P. coquenani +
P. oinoco
P. yekuana
more dorsal-fin rays (Armbruster, 2004b). Al-
though an increased number of dorsal-fin rays
may be useful for diagnosing genera
(i.e.,
Ptery-
goplichthys)
and clades within Hypostominae
(i.e.,
Acanthicus group, Chaetostoma group); it seems
that in the case of P. pectegenitor
(as
in Pogonopo-
ma obscurum), the increased
number of dorsal-fin
rays is an autapomorphy diagnostic only at the
species
level. Pseudancistrus
pectegenifor shares a
number
of synapomorphies
with the genusPseud-
ancistrus, therefore erection
of a new genus is not
warranted. Indeed, much of the morphology of
P.pectegenitor is rather autapomorphic. For ex-
amples, there are a very high number of teeth,
the body seems
relatively short, and the cheek
odontodes are very elongate whereas the trend
in Pseudancistrus is towards the reduction of the
size of the cheek odontodes. Regardless, P. pecte-
genitor
has all but one of the synapomorphies of
Pseudancistrus and it shares
the synapomorphy
of the dentary papillae with P. coquenani, P. ori-
noco, and P.yekuana,
a characteristic seen else-
where only inChaetostoma
and some Cordylancis-
trus.
If the specimens of Pseudancistrus yekuana were
not collected sympatrically with P. orinoco they
might not have been readily separated as a unique
species. The two species are similar in general
form and color; however, seeing
the two species
side by side in the same collection makes the
identification of P.yekuana
as a new species
rather obvious. The shape of P.yekuana is also
quite different from the other species of Pseudan-
cistrus assuggested by the Principal
Components
Analysis
(Fig.6).
Although this
PCA is based on
few individuals of P. yekuana, the degree of dif-
ference between it and the other Pseudancistrus
in the analysis
is large,
and presumed indicative
of true differences.
Pseudancistrus yekuana
appears to be fully
mature at a small size. The cleared and stained
specimen
(35.0
mm SL) had
ova
more mature than
would be seen in juveniles, and the largest
specimen
is only 42.7
mm SL,
whereas
the largest
specimen of either P. orinoco or P. coquenani ex-
amined
is 105.8 mm SL. The dorsal surface of the
head
supports
more
odontodes at a smaller size
in P. yekuana
than in P. orinoco. The 42.7 mm SL
type of P.yekuana, for example,
has the head
fully supporting odontodes while similarly sized
P. orinoco from the
same
locality have large
naked
patches on the frontal and supraoccipital. Sev-
eral morphometric ratios separated
P.yekuana
tet
lB =
'fi8
=;
!-
o@
OD
=g
DO
o
to
l!
Vr-
-0.5 -0.4 -0.3 -0.2
-0.1 0 0.1 0.2
PC3
Fig. 6. Principal
Components
Analysis
of species of
Pseudancistrus with
dentary papillae. Strongest
loading
characters shown
with their
direction
of influence.
Discussion
Armbruster (2004a)
diagnosed
Pseudancistrus with
the following: no suture between pterotic-supra-
cleithrum and hyomandibula (34-0,
reversal;
character numbers and states from Armbruster,
2004b),
no contact of the hyomandibula with the
prootic (35-1), straight, spoon-shaped
anterior
process
of metapterygoid (58-1),
nasal bone not
much wider than laterosensory
canal running
through it (105-0),
sphenotic
not contacting
pos-
teriormost infraorbital externally (117-1),
and a
short ventral ridge on the pelvic basipterygium
(172-1,lost
in some species).
Pseudancistrus pecte-
genitor has four of these five characteristics,
varying only in that the sphenotic does contact
the posteriormost infraorbital externally
. P
seud-
ancistrus
yekuana
also has four of these character-
istics; varying only in that there is a suture be-
tween the pterotic-supracleithrum and the hyo-
mandibula; however, the suture present
is very
weak.
Pseudancistrus pectegenitor is unique among
Pseudancistrus in having an increased
number of
dorsal-fin rays (i.e., greater than seven).
An in-
creased
number of dorsal-fin rays is not common
in hypostomines; however, there are several ex-
amples: one species of Pogonopomahas ten dorsal-
fin rays
(Quevedo
and
Reis, 2002), Pterygoplichthys
usually has 10 or more dorsal-fin rays, and the
Acanthicus
group (Acanthicus,
Leporacanthicus,
Megalancistrus, and Pseudacanthicu) and the Cha-
etostoma
group (Chaetostoma,
Cordylancistrus,
Dolichancistrus, and Leptoancistrus) have eight or
Luian et al.: Two new Pseutlancistrus
and P. orinoco; however, only three specimens of
P. yekuana were measured, and these characters
are suspect until more specimens become avail-
able. The snout of P. yekuana
is much more elon-
gate when compared against specimens of similar
size, the pectoral fins much shorter, and the
lower lip is so long that it almost reaches beyond
the pectoral girdle (see Diagnosis).
Comparative material, Pseudancistrus
coquenani: Yen-
ezuela:
AMNH 31023, 6, 53.9-62.9 mm SL;
Bolivar: Rio
Paragua
at Gusano Rapids, Rio
Caroni
dr., 1-1.5 hours
upriver from Rio Carapo mouth (5"30'N 63"36'W).
-
MCNG "17525,2,
@.6-94.4 mm SL; Bolivar: Rfo Caroni
dr., Rio Supamo 12
km N of la Piedra del Supamo
(6'59'N 62"23'W).
- MCNG 18339, 5, 58.8-94.4
mm SL;
Rio Caroni dr., middle Rio Tocomo
below entrance of
railway below high tension cables (7"50'40"N
40'63'
05"W).
- MCNG 18470,6,52.2-62.9 mm SL;
Bolivar, Rio
Caroni dr., Rfo Claro east of Los Tanques
(7"55'20"N
63'06'05"W).
- NMW 48023, 2 syntypes, 75.5-78.6 mm
SL; Bolivar: Rio Caroni dr., Rio Coquenan.
P. orinoco:
Venezuela: ANSP 1@6N,5,79.i79.0 mm
SL; Amazonas: Rio Orinoco, Raudales de Atures, at
Culebra, ca 7 km S of Puerto Ayacucho
(5'35'N
67'31'W).
- ANSP 165824,1,78.1 mm SL; Apure: Rio Arauca dr.,
cafro
near El Yagua
(7'30'N 68'20'W).
- AUM 39479,5,
56.7-82.4 mmSL, same data as types of P.yekuana.
-
AUM 39542,
5, 67.5-105.8 mm SL; Amazonas: Rio Ori-
noco dr., Rio Ventuari at Raudales Tencua, 56 km ESE
of San Juan de Manapiare (5'02'59"N 65'37'38"W).
-
{UM42779,1,93.1
mm SL; Amazonas: Rio Casiquiare
dr., Rio Siapa,
rapids 154 km E of San Carlos de Rio
Negro
(1"36'12"N
65"42'57"W).
- AUM 42'1U,1, 80.6 mm
SL; Amazonas: Rio
Casiquiare dr., Rio Siapa, Raudales
Gallineta, 142
km E of San Carlos de Rio Negro (1'49'
00"N 65'47'41"W).-MCNG2020{, 1,61.0 mmSL; Apure:
Rio Capanaparo
dr., at CORPOVEN camp and Laguna
Larga, Rio Apure dr. (6'31'50"N
67"23'48"W).
- MCNG
21631,1,70.7 mm SL;
Amazonas:
Rio Orinoco dr., Rio
Cataniapo at the bridge just S of Puerto Ayacucho
(5'36'N 67'35'30"W).
- MCNG 25794, 1,48.2 mm SL;
Amazonas: Rio Orinoco dr., Rio Ocamo at Raudal Ar-
ata
(3"8"N
64"34'W).
- MCNG 30407,2,45.5-58.4 mm
SL;
Amazonas:
Rio Orinoco at Raudales
de Atures.
Acknowledgements
This project was funded by Planetary Biodiversity In-
ventory: All Catfish Species
(Siluriformes)
- Phase
I of
an Inventory of the Otophysi, a 5 year grant through
the US National Science Foundation to describe all
species of catfishes
(NSF
DEB-0315963) and NSF grant
DEB-0107751 to JWA. We would like to express our
deepest
appreciation to D. Taphorn and O. Le6n for
their invaluable help in obtaining permits, logistical
support, aiding in fieldwork, and loan of materials.
lchthyol. Explor. Freshwaters, Vol.
18, No. 2
173
Thanks
especially to O. Le6n whose
skilled cast netting
collected the specimens
ol Pseudancistrns
yekuana.
Thanks
to M. Arce, R. Betancur,
A. Luna, Rafael
Pajua,
L. deSouza, T. Wesley, M. Grant, E. Richmond,
J.
Vala-
dez, D. Brooks, F. Brito, L. Camico, O. Santa Ella, and
D. Werneke for aid in collecting specimens and R.
Betancur for the Spanish abstract.
Literature cited
Agostinho, A. A. 1985. Estrutura da populaqdo,
idade
e crescimento de Rhinelepis
aspera
(Agassiz,7829)
(Osteichthyes,
Loricariidae)
do rio Paranapanema,
Pr. PhD dissertation.
Universidade Federal de Sio
Carlos, 56o Carlos.
Armbruster, J.
W. 1998.
Modifications of the digestive
tract for holding air in loricariid and scoloplacid
catfishes. Copeia,'1,998:
663-675.
- 2003. P
eckol t ia saba
j i, a new
species from the
Guyana
Shield (Siluriformes: Loricariidae). Zootaxa, 344:.
1-72.
- 20Ma. Pseudancistrus
sidereus,
a new species from
southern Venezuela (Siluriformes: Loricariidae)
with a redescription
of P
seudancistrus. Zootaxa,
628:
1-15.
- 2004b. Phylogenetic relationships of the sucker-
mouth armored catfishes
(Loricariidae) with em-
phasis
on the Hypostominae and the Ancistrinae.
Zoological Journal of the Linnean Society, 141: 1-
80.
- 2005. The loricariid catfish genus Iasiancistrus
(Sil-
uriformes) with descriptions
of two new species.
Neotropical lchthyology, 3: 549-569.
Armbruster,
J.W.,
N. K. Lujan
& D. C.
Taphorn.2007.
Four new Hypancistrus
(Siluriformes:
Loricariidae)
from Amazonas, Venezuela.
Copeia (in press).
Armbruster, l. W. & Provenzano
R. 2000. Four new
species
of the suckermouth
armored catfish genus
Lasiancistrus
(Loricariidae: Ancistrinae). Ichthyo-
logical Exploration of Freshwaters, 1 1:
241-254.
Darwin, C. R. 1882. The descent
of man and selection
in relation to sex, Second Edition, John Murray
London,693
pp.
Evers, H.-G. & I. Seidel 2005.
Catfish atlas Volume 1:
South American catfishes of the families Loricari-
idae,
Cetopsidae, Nematogenyidae
and
Trichomyc-
teridae.
Mergus, Melle.
Gross,
M. R. & R. C. Sargent.
1985. The evolution oI
male and female parental
care in fishes. American
Zoologist, 25: 807
-822.
Isbriicker, L J.
H., H. Nijssen
& P. Cala. 7988. Lithoxan-
cistrus orinoco, nouveau
genre et espEce de poisson-
chat cuirass€ de Rio Orinoco en Colombie (Pisces,
Siluriformes, Loricariidae).
Reure Franqaise
d'Aqua-
riologie et Herp6tologie, 15: 13-16
Isbrticker I. J. H., I. Seidel,
J. P. Michels, E. Schraml &
A. Werner. 2001. Diagnose vierzehn neuer Gat-
tungen der Familie Loricariidae Rafinesque,
1815
774
(Teleostei,
Ostariophysi).
Pp. 1 7-24 in: R.
Stawikowski
(ed.), Datz-Sonderheft Harnischwelse 2. Eugen
lJlmer, Stuftgart.
Leviton, A. E., R. H. Gibbs, E. Heal & H. E. Dawson.
1985. Standards in herpetology and ichthyology:
Part I. Standard symbolic codes for institutional
resource
collections
in herpetology and ichthyology.
Copeia,
1985:
802-832.
Mazzoni, R. & E. P. Caramaschi. 1997. Observation on
the reproductive biology of female Hypostomus
luetkeniLac6pdde 1803. Ecology of Freshwater Fish,
5:53-56.
Quevedo,
R. & R. E. Reis.2002. Pogonopoma obscurum:
a new species of loricariid catfishe (Siluriformes:
Loricariidae) from Southern Brazil, with comments
on the genus Pogonopoma. Copeia, 20(J.2:402-41,0.
Sabaj,
M. H., I. W. Armbruster & L. M. Page. 1999.
Spawning in Ancistrus
(Siluriformes:
Loricariidae)
with comments on the evolution of snout tentacles
as a novel reproductive strategy:
larval mimicry.
Ichthyological Exploration of Freshwaters,'1,0: 217-
229.
Suzuki,
H.I., A. A. Agostinho & K. O. Winemiller.2000.
Relationship between oocyte morphology and re
productive strategy in loricariid catfishes of the
Parana River, Brazil. fournal of Fish Biology, 57:
797-807.
Taylor, W. R. & G. C. Van Dyke. 1985. Revised proce-
dures for staining and clearing small fishes and
other vertebrates for bone and cartilage study.
Cybium, 9:707-1.19.
Werneke, D.C.,
I.W. Armbruster, N. K. Lujan
& D. C.
Taphorn. 2005. Hemiancistrus guahiborum, a rrew
suckermouth armored catfish from Southern Ven-
ezuela (Siluriformes: Loricariidae). Neotropical
Ichthyology, 3: 543-548.
Werneke, D. C., M. H. Sabaj,
N. K. Lujan &J. W. Arm-
bruster. 2Cf.5. Baryancistrus
demantoides and Hemi-
ancistrus suboiridis, two new uniquely colored
species of catfishes from Venezuela (Siluriformes:
Loricariidae). Neotropical lchthyology, 3: 533-542.
Winemiller, K. O. 1989. Patterns
of variation in life his-
tory among South American fishes in seasonal
environments. Oecologia, 81
: 22*241.
Received 30 August 2005
Revised 15 February 2ffi7
Accepted 18 April 2007
Luian et al.: Two new Pseudancistrus
