Neotropical Ichthyology, 17(2): e180160, 2019
DOI: 10.1590/1982-0224-20180160
Copyright © 2019 Sociedade Brasileira de Ictiologia
Journal homepage: www.scielo.br/ni
Published online: 18 July 2019 (ISSN 1982-0224)
Printed: 30 June 2019 (ISSN 1679-6225)
Original article
A new species of whiptail armored catfish, genus Pseudohemiodon
(Siluriformes: Loricariidae) from the Orinoco River basin,
Llanos region of Colombia and Venezuela
Yecid Andrey Rojas-Molina1, Francisco Provenzano-Rizzi2 and Hernando Ramírez-Gil1
A new species of whiptail armored catfish belonging to the genus Pseudohemiodon is described. The new species inhabits
aquatic systems of the Orinoco River basin, mostly in the Llanos region of Colombia and Venezuela. Previously, it had
identified as P. laticeps erroneously. The genus Pseudohemiodon includes seven known species inhabit Amazon and ParanáParaguay-Uruguay rivers basins. The new species is distinguished from congeners by the combination of the following
characters: abdomen totally covered; area in front of gill opening without plates, ventrally; dorsal body color pattern without
transversal dark bands, mostly in the caudal peduncle; head with straight sides; head and caudal peduncle narrower.
Keywords: Diversity, Freshwater fishes, South America, Systematic, Taxonomy.
Se describe una nueva especie de bagre corroncho cola de látigo perteneciente al género Pseudohemiodon. La nueva especie
habita los sistemas acuáticos de la cuenca del río Orinoco, principalmente en la región de los Llanos de Colombia y Venezuela.
Anteriormente, fue identificada como P. laticeps de forma errónea. El género Pseudohemiodon incluye siete especies
conocidas que habitan en las cuencas de los ríos Amazonas y Paraná-Paraguay-Uruguay. La nueva especie se distingue de
todos sus congéneres por la combinación de los siguientes caracteres: abdomen totalmente cubierto; sin placas delante de la
abertura branquial, ventralmente; patrón dorsal de coloración del cuerpo sin bandas oscuras transversales, principalmente en
el pedúnculo caudal; lados de la cabeza rectos; cabeza y pedúnculo caudal más estrechos.
Palabras-clave: Diversidad, Peces de agua dulce, Sistemática, Sur América, Taxonomía.
Introduction
The genus Pseudohemiodon was proposed by Bleeker
(1862) to accommodate Hemiodon platycephalus Kner,
1853, from the Cuiabá River, Brazil (Isbrücker, 1980).
The genus belongs to the subfamily Loricariinae, tribe
Loricariini, Pseudohemiodon-group (Isbrücker, Nijssen,
1974; Covain et al., 2016). The Pseudohemiodon-group was
originally proposed by Isbrücker, Nijssen (1974), but later
was changed to the sub-tribe Planiloricariina (Isbrücker,
Nijssen, 1986a), this taxonomic level was used by Rapp
Py-Daniel (1997) and Provenzano (2011). Covain, FischMuller (2007) used again the name Pseudohemiodongroup, name employed currently (Covain et al., 2016). The
group includes species that belong or have been included
in the genera: Apistoloricaria Isbrücker, Nijssen, 1986;
Crossoloricaria Isbrücker, 1979; Dentectus Martín Salazar,
Isbrücker, Nijssen, 1982; Planiloricaria Isbrücker, 1971;
Pseudohemiodon Bleeker, 1862; Pyxiloricaria Isbrücker,
Nijssen, 1984 and Rhadinoloricaria Isbrücker, Nijssen,
1974 (Isbrücker, 1971, 1975, 1979, 1980; Isbrücker, Nijssen,
1974, 1978, 1983, 1984, 1986a, b; Martín Salazar et al.,
1982; Nijssen, Isbrücker, 1988; Chang, Castro, 1999; Rapp
Py-Daniel, 1997; Provenzano, 2011; Covain et al., 2016).
Diagnosis of the genus Pseudohemiodon is not precise,
and shows some ambiguity. Kner (1853) determined
that Hemiodon platycephalus, type species of the genus,
does not have teeth in the upper jaw, and Bleeker (1862)
used this feature as diagnostic character for the genus
Pseudohemiodon (Isbrücker, 1971). From its establishment
until 1971, the genus was considered invalid or a subgenus
of Loricaria, but that year Pseudohemiodon was revalidated
and two subgenera, Pseudohemiodon and Planiloricaria
were recognized (Isbrücker, 1971). In the same paper,
Universidad de los Llanos-UNILLANOS, Km 12 Vía Puerto López, PBX, 661 68 00 Villavicencio, Meta, Colombia. (YARM)
yecid.rojas@unillanos.edu.co, https://orcid.org/0000-0001-6761-5171; (HRG) hernando.ramirez@unillanos.edu.co, https://orcid.
org/0000-0002-0166-3047.
2
Departamento de Biología, Facultad de Ciencias, Escuela Politécnica Nacional, Quito, Ecuador, and Centro MBUCV, Instituto de
Zoología y Ecología Tropical, Facultad de Ciencias, Universidad Central de Venezuela, Caracas, Venezuela. francisco.provenzano@
epn.edu.ec, https://orcid.org/0000-0003-3296-2311 (corresponding author).
1
e180160[1]
Neotropical Ichthyology, 17(2): e180160, 2019
2
New Pseudohemiodon from the Orinoco River basin
Isbrücker presented a new diagnosis for the genus, but
maintained the absence of teeth in upper jaw as a diagnostic
feature. Isbrücker (1973) reported that Pseudohemiodon
(Pseudohemiodon) included six species, but cast doubt on
the absence of teeth in upper jaw as a diagnostic character,
because five of the six species were found to have teeth in
both jaws. Isbrücker, Nijssen (1974) considered the absence
of teeth in the upper jaw of P. platycephalus (type species),
an artifact, and indicated that all species of Pseudohemiodon
have teeth in both jaws; in the same paper they elevated
Planiloricaria to generic rank.
Since 1971, the number and the species included in
Pseudohemiodon has changed (Isbrücker, 1971, 1973, 1975,
1979; Isbrücker, Nijssen, 1974, 1978, 1986a). Currently it
includes seven species (Fricke et al., 2019). Four species
inhabit the Amazon River basin: Pseudohemiodon lamina
(Günther, 1868), Pseudohemiodon amazonum (Delsman,
1941), Pseudohemiodon thorectes Isbrücker, 1975 and
Pseudohemiodon apithanos Isbrücker, Nijssen, 1978,
and three species are cited for the Uruguay, Paraná and
Paraguay, rivers basins: Pseudohemiodon platycephalus
(Kner, 1853), Pseudohemiodon laticeps (Regan, 1904)
and Pseudohemiodon devincenzii (Soriano Señorans,
1950) (Isbrücker, 1975, 1979, 1980; Isbrücker, Nijssen,
1978; Covain, Fisch-Muller, 2007; Covain et al., 2016).
The original description of P. devincenzii is brief and do
not provide distinctive characteristics (Soriano Señorans,
1950). The holotype, a specimen with 165 mm of TL and
143 mm of SL, has no figure or image known. Isbrücker
(1979) indicate holotype of P. devincenzii is lost, and
differences, pointed by Soriano Señorans (1950), between
P. devincenzii and P. laticeps maybe related with methods
and measures used. López-Rojas, Machado-Allison (1975)
identify a group of specimens from the Orinoco River
basin as P. laticeps. Isbrücker, Nijssen (1978) suggest that
the specimens analyzed by López-Rojas, Machado-Allison
(1975) could be close or belong to P. aphitanos, but the lack
of morphometric data prevents a certain assignment.
Herein, a new species of the genus Pseudohemiodon is
described based on specimens captured in aquatic systems
of the Orinoco River basin of Colombia and Venezuela,
mostly in the Llanos region.
Material and Methods
The generic placement and validity of this new species
were established through the comparison with species of
the Pseudohemiodon group. For comparative analyses
we used original descriptions and figures of species of
Pseudohemiodon (Kner, 1853; Regan, 1904; Delsman,
1941; Soriano Señorans, 1950; Isbrücker, 1975) and
available specimens of species listed in comparative
material examined. Also, images of type specimens from
the ACSI image database (Morris et al., 2006) were used.
Observations, measurements and counts were made using
a Stemi dv4 stereoscopic microscope and Ubermann digital
e180160[2]
calipers. Measurements and counts were those proposed by
Boeseman (1971), Isbrücker, Nijssen (1978) and Fichberg
et al. (2014). Counts and nomenclature of plates follow
Schaefer (1997). Measurements were taken on left side,
and are expressed as percentage of standard length, head
length, or in the proportions commonly used in old original
descriptions for easier comparison. Museum acronyms from
comparative material examined follow Sabaj (2016).
Results
Pseudohemiodon unillano, new species
urn:lsid:zoobank.org:act:76D2CFB3-7E7E-44F2-A08F31EA54B63398
Figs. 1-4; Tab. 1
Loricaria laticeps.—López-Rojas,
[Bocono River, Venezuela].
Machado-Allison,
1975:52
Holotype. IAvH-P 19034, 162.0 mm SL, Colombia,
Departamento Meta, Orinoco River basin, Guayuriba River,
tributary to the upper Meta River, vía Puerto López, near
Villavicencio, 03°55’02.6”N 73°06’11”W, 197 m asl, 2 Sep
2014, H. Ramírez-Gil and A. Ortega-Lara.
Paratypes. Colombia, Departamento Meta: IAvH-P 19089,
1, 62.4 mm SL, same data of holotype. IAvH-P 19035,
1, 175.3 mm SL, same data of holotype, except date of
collection 01 Dec 2014. IAvH-P 19020 1, 155.7 mm SL,
Guayuriba River, tributary to the upper Meta River, Orinoco
River basin, 03°58’59.4”N 73°24’27.3”W, 338 m asl, 19
Nov 2014, H. Ramírez-Gil and A. Ortega-Lara. IAvH-P
19088, 1, 183.2 mm SL, Guayuriba River, tributary to the
upper Meta River, Orinoco River basin, 03°57’38.4”N
73°16’26.3 “W, 255 m asl, 09 Jun 2014, H. Ramírez-Gil
and A. Ortega-Lara. Departamento Casanare: MPUJ 7354,
1, 124.4 mm SL, caño Guanapalo, tributary of Pauto River,
Meta River, Orinoco River basin, Municipio de San Luis de
Palenque, vereda El Romero, 03°30’38.9”N 71°56’46.5”W,
171 m asl, 24 Mar 2015, V. Preciado and party. IAvH-P 3941,
1, 173.4 mm SL, Tocaria River 1994, V. Ortiz. IAvH-P 3942,
1, 129.9 mm SL, Tocaria River, 05°33’N 72°13’W, 02 Mar
1994, V. Ortiz. IAvH-P 3944, 1 ex., 171.4 mm SL, Tocaria
River, 05°33’N 72°13’W, 02 Mar 1994, V. Ortiz. IAvH-P
3943, 2, 167.5-195.0 mm SL, Cusiana River, 04°31’N
71°51’W, 11 Nov 1994, V. Ortiz. IAvH-P 7680, 1, 144.5 mm
SL, Cravo Sur River, 04°42’N 71°36’W, 20 Nov 1995, V.
Ortiz. Departamento Arauca: IAvH-P 4823, 5, 132.3-200.1
mm SL, Arauquita, Agua Limon River, 06°55’N 70°58’W,
02 Nov 1994, G. Castaño. IAvH-P 10849, 1, 110.9 mm SL,
Tocaria River, 26 Jun 1983, O. Rodríguez. IAvH-P-18796,
5, 67.9-169.0 mm SL, Caño Guanapalo, San Luis del
Palenque, 03°30’38.9”N 71°56’46.5”W, 19 Aug 2015, V.
Preciado. IAvH-P 19042, 5, 86.7-198.5 mm SL, Arauquita,
Neotropical Ichthyology, 17(2): e180160, 2019
3
Y. A. Rojas-Molina, F. Provenzano-Rizzi & H. Ramírez-Gil
Agua Limon River, 01 Nov 1994, G. Castaño. Venezuela,
Estado Apure: MBUCV-V-20148, 10, 101.6-166.9 mm SL,
Apure River, near San Fernando de Apure, 07°52’39”N
67°25’28”W, 12 May 1989, F. Mago-Leccia and party.
Estado Barinas: MCNG-51446, 6, 100.3-147.8 mm de SL,
Portuguesa River, between Barinas and Guárico states,
07°33’42”N 67°19’18”W, 03 Jan 2004, O. Castillo. MCNG5925, 5, 117.3-251.2 mm SL, Boconó River, at La Veguita,
08°50’10”N 69°59’30”W, 21 Jul 1980, D. Taphorn. Estado
Portuguesa: MBUCV-V-12984, 15, 164.6-226.9 mm SL,
Boconó River, Puerto Sunsún, 08°45’11”N 69°50’22”W, 25
Sep 1973, F. Mago, O. Silva, A. Machado and L. Aguana.
Non-type specimens. Venezuela, Estado Apure: MCNG
13866, 1, 122.8 mm SL, Apure River, 10 km downstream
San Fernando de Apure, 07°51’50”N 67°23’30”W, 15 May
1985, D. Taphorn. Estado Barinas: MBUCV-V-12923, 1,
63.0 mm SL, Masparro River, at Libertad bridge, 08°20’33”N
69°39’20”W, 31 Jul 1981, F. Provenzano, O. Castillo and L.
Aguana. MCNG 11974, 4, 29.5-45.4 mm SL, Caparo River,
10 Km from El Cantón, 07°29’30”N 71°13’00”W, 21 Dec
1983, D. Taphorn. Estado Bolívar: MBUCV-V-16885, 2,
78.6-80.5 mm SL, Orinoco River, at Caura River confluence,
beaches, canals and lagoon nearby Puerto Las Majadas,
approx. 07º38.6’N 64º50’W, 23 Nov 1985, B. Chernoff,
J.G. Lundberg, and L. Aguana. MBUCV-V-16900, 1, 87.2
mm SL, Cuchivero River, at ferry boat crossing point,
07º29’N 65º35’W, 17 Nov 1985, B. Chernoff and party.
Estado Cojedes: MBUCV-V-12781, 2, 50.5-51.4 mm SL,
Salinas River, Pao viejo River channel, NE from El Baúl,
09°15’N 68°11’W, 25 Feb 1950, A. Fernández-Yépez.
Estado Guárico: MBUCV-V-16859, 6, 59.2-106.9 mm
SL, Guariquito River, at confluence with Orinoco River,
07°39’28”N 66°19’52”W, 25 Nov 1985, B. Chernoff, B.
Saúl, R. Royero and L. Aguana. Estado Monagas: MCNG
29133, 1, 76.3 mm SL, Guanipa River, at the bridge, approx.
5 km S del Aguasay, 09°22’06”N 63°46’47”W, 1 Jul 1994,
D. Taphorn. Estado Portuguesa: MCNG 5539, 4, 142.2222.0 mm SL, Boconó River, La Veguita, 08°50’10”N
69°59’30”W, 11 Jun 1982, D. Taphorn. MCNG 19394, 1,
277.1 mm SL, Portuguesa River, at the bridge on principal
highway, 09°05’00”N 69°41’30”W, 31 Mar 1987, ASF87-2.
Fig. 1. Pseudohemiodon unillano, new species, holotype, IAvH-P 19034, 162.0 mm SL. Photograph by J. Lopez-Castaño.
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Neotropical Ichthyology, 17(2): e180160, 2019
4
New Pseudohemiodon from the Orinoco River basin
Diagnosis. Pseudohemiodon unillano is distinguished
from P. platycephalus, P. amazonum and P. thorectes by
its abdomen totally covered with small to medium-sized,
irregularly shaped plates (vs. abdomen partially covered, or
if completely covered, plates on central row are wide and
rectangular). Further distinguished from P. lamina by the
absence of bony plates anterior to gill openings, in ventral
view of head (vs. presence of one or more plates in front
of the gill openings). From P. apithanos by its body color
pattern, dorsally, uniform light brown with dark fine lines or
with dark (black) spots small and irregular; caudal peduncle
without dark transverse bands (vs. anterior region of body
very dark brown, or light brown with dark-colored fine lines,
and caudal peduncle with three dark transverse bands, the
first, broad, located at the end of dorsal-fin, the other two
thinner and posterior; transversal bands could be absent in
larger specimens). From P. laticeps by its head narrower,
cleithral width 1.0 times or less in HL, with straight sides
(vs. head wider, cleithral width 1.1 or more times in HL,
with sides slightly concave near tip of snout).
Description. Morphometric data presented in Tab. 1. Head
and body very depressed, caudal peduncle long, narrow
and very depressed, without adipose-fin. Body deepest at
dorsal-fin origin or slightly ahead, and widest at cleithrum,
becoming narrower posteriorly, gradually, to caudal-fin
origin. Dorsal profile of body from tip of snout through
anterior border of eye, straight and sloping more or less
45°, from this point to dorsal-fin origin, straight and gently
inclined or gently convex, then descending straight to
caudal-fin origin. Ventral profile of body flat and straight.
Head triangular, in dorsal view, sides straight. Snout slightly
projected, with rounded tip. Pectoral-fin origin insertions at
vertical through posterior margin of orbit. Dorsal-fin origin
opposite pelvic-fin origin. Anal-fin origin at lateral plate
number 10 (Fig. 1).
Eyes located dorsally, orbit with evident anteroventral
and posterior notch. From nostrils, parallel slight keels
run posteriorly, passing between eyes to anterior tip
of supraoccipital. Keels convergent posteriorly, over
supraoccipital, becoming narrower and parallels, to posterior
tip on supraoccipital. Predorsal region with three single
plates, first and second plate with parallel low keels, and
third plate with single one, on midline (Fig. 1).
Body sides with 31-32 plates at median lateral series, 1315 coalescent plates (double keel) and 17-19 posterior plates
(one keel). Six to eight thoracic plates (between posterior
end of pectoral-fin base and origin of pelvic-fin base). Postdorsal plates 20-22 and post-anal plates 17-20. Four plates
along dorsal-fin base and two or three plates along anal-fin
base.
Abdomen completely covered in specimens greater
than 70.0 mm SL, with small to medium-sized, irregularly,
polygonal-shaped plates, smaller over pectoral girdle.
Ventral surface of head naked, except by plates surrounding
its border and on snout; no plates anterior to gill openings.
e180160[4]
Tab. 1. Morphometric data of Pseudohemiodon unillano,
new species, in % of standard length, n=30.
Characters
Holotype Average STD Min
Max
Standard length (SL)
162.0
62.4 200.5
Head length
24.8
24.5
1.0
22.9
26.7
Predorsal length
34.9
34.3
1.0
32.1
36.8
Postdorsal length
55.8
56.8
1.2
53.7
59.2
Preanal length
49.1
48.0
1.1
46.0
51.0
Cleithral width
23.5
23.0
1.2
20.8
24.9
Postanal length
46.2
47.5
1.4
44.0
49.8
Pre-pectoral length
20.0
19.4
0.9
17.9
22.0
Abdominal length
15.3
14.1
0.9
12.1
15.6
Thoracic length
19.7
19.2
0.9
17.1
20.8
Dorsal-fin length
21.8
20.1
1.3
17.6
23.1
Pectoral-fin length
19.3
18.5
0.8
16.5
19.8
Last pectoral-ray length
7.7
8.0
0.6
6.7
9.4
Pelvic-fin length
14.4
14.0
1.3
11.7
16.5
Anal-fin length
17.1
15.7
1.0
14.0
17.6
Body depth at dorsal-fin origin
8.8
8.6
0.9
7.2
10.2
Minimum caudal peduncle depth
1.8
1.6
0.2
1.2
2.0
Body width at dorsal-fin origin
18.9
17.9
1.8
12.1
21.2
Body width at anal-fin origin
15.2
14.7
1.1
11.9
17.1
Body width at caudal-fin origin
3.1
2.7
0.4
1.5
3.4
Head width
24.6
24.1
0.8
22.5
25.9
Head depth
7.8
7.5
0.6
6.5
9.0
Interorbital distance
4.3
4.4
0.6
3.8
6.7
Orbital diameter
1.7
1.9
0.3
1.4
2.4
Orbital-predorsal length
19.1
18.1
0.7
16.7
19.8
Snout length
14.5
13.8
0.6
11.6
14.8
Snout nostril length
11.9
11.5
0.5
10.5
12.7
Nostril length
1.9
1.5
0.3
1.0
2.0
Inter-nostril distance
2.0
2.1
0.2
1.8
2.3
Dentary length
0.9
0.9
0.1
0.6
1.2
Lower lip width
14.2
12.4
1.5
8.5
15.3
Lower lip length
2.0
2.1
0.4
1.4
2.8
Oral cavity width
6.3
6.0
0.5
4.9
7.1
Premaxillary ramus
0.8
0.8
0.1
0.6
1.2
Branchiostegal membrane smooth and uniform, without
wrinkled flap on anterior margin or any protuberance or fold
(Fig. 1). Anus projected as very small tube, urogenital papilla
not visible, apparently attached to posterior surface of anal
tube. Anus delimited by narrow naked area, surrounded by
plates (Fig. 1).
Mouth ventral with expanded, thin and laminar lips. Upper
lip very narrow, its border with conical small barbels or cirri,
elongated and unbranched, long and short cirri interspersed.
Upper lip surface has sparse small papillae. Border of upper lip
continuous with maxillary barbel, extending to gill opening,
sometimes reaching pectoral-fin base. Maxillary barbel with
small, conical, unbranched cirri. Lower lip wide, its border
with elongated and branched conical small barbels, central
shorter. Lower lip surface covered with short, fleshy, soft
and thick papillae, sometimes little elongated (Figs. 1, 2).
Neotropical Ichthyology, 17(2): e180160, 2019
Y. A. Rojas-Molina, F. Provenzano-Rizzi & H. Ramírez-Gil
On distal side of each premaxilla, two or three elongate,
soft, fleshy, cylindrical, unbranched small barbels. At center
of oral cavity and posterior to premaxillaries, single small
barbel long, soft, fleshy, cylindrical and unbranched (Figs.
2, 3). Teeth present in both jaws, very minute but evident,
5
all with same size; bicuspids asymmetrical, but sometimes
symmetric after wear; inner cusp more developed, spoonshaped, outer cusp very small, sometimes not visible, and
pointed; apex yellow or golden. Premaxillary teeth 5-9,
dentary teeth 5-10 (Fig. 3).
Fig. 2. Pseudohemiodon unillano, paratype, IAvH-P 19088, 183.2 mm SL. Detail of mouth in live specimen. Photograph by
A. Ortega-Lara.
Fig. 3. Pseudohemiodon unillano, paratype, IAvH-P 19088, 183.2 mm SL. Detail of buccal ornamentation and teeth.
Photograph by L. M. Mesa.
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Neotropical Ichthyology, 17(2): e180160, 2019
6
New Pseudohemiodon from the Orinoco River basin
Dorsal-fin rays i,7; pectoral-fin rays i,6; pelvic-fin
rays i,5; anal-fin rays i,5; and caudal-fin rays i,10,i. Tip
of pelvic fins surpassing origin of anal fin. Caudal fin
slightly bifurcated, with unbranched rays longer than
branched. Upper unbranched ray of caudal-fin extend as
very long filament (Fig. 4). In examined specimens, first
unbranched ray of dorsal, pectoral, pelvic and anal fins
not elongated as filament.
Largest specimen examined 277.1 mm SL (MCNG
19394).
Color in alcohol. Specimens preserved in 70% alcohol
with dorsal surface of head and body, yellowish or light
brown, uniform, sometimes with random pattern of
irregular square or rectangular, dark or brown blotches,
mostly on head and trunk (Fig. 1). Ventral surface
of head and body, whitish, yellowish, or pale brown,
uniform (Fig. 1). Dorsal, pectoral, pelvic and caudalfins with rectangular or square dark or black blotches
on rays; interradial membranes hyaline. Dorsal, pectoral
and pelvic-fins spines with five, seven and four black
blotches, respectively. Anal-fin uniform, may be whitish
or yellowish (Fig. 1). Caudal-fin with three to five
rectangular black blotches on rays, sometimes blotches
faded or as two or three transverse dark bands when
caudal-fin not completely open (Fig. 1).
Coloration in life. Live specimens with dorsal and
lateral surfaces of body may be yellowish or grayish
with vermicular pattern of dark, very narrow lines,
and iridescent tonalities. Ventral surface of body, may
be whitish or yellowish, uniform. Edge of snout light
brown. Dorsal, pectoral and pelvic fins with dark or black
blotches on rays; interradial membranes hyaline. Dorsalfin with rectangular black blotches similar in size and
shape in all rays. Pectoral-fin rays with rectangular black
blotches at bases, and square-shaped on rest of fin. Pelvicfin rays base, and rays five and six whitish, uniform;
rays one to four with rectangular black blotches on its
distal two thirds. Anal-fin may be whitish or yellowish,
uniform, without blotches. Caudal-fin base, whitish, rays
with six to eight black, rectangular blotches; elongated,
dorsal unbranched ray, with black blotches until its end.
Interradial membrane of all fins hyaline (Fig. 4).
Geographical distribution. Records indicate that the
species lives along Orinoco River basin and has a wide
geographical distribution; mostly it is found in flatlands
region (Llanos), from the foothills of the Eastern Andes
in Colombia and the Mérida Cordillera until near the
Orinoco River delta, in Venezuela (Fig. 5).
Etymology. The species name “unillano”, is taken from
the Latin prefix “uni” which means: one, unique, and from
the Spanish word “llano” which means: a plain terrain.
Alluding the savannas or plains share by Colombia and
Venezuela, crossed by tributaries and the Orinoco River
itself. A noun in apposition.
Fig. 4. Pseudohemiodon unillano, paratype, IAvH-P 19088, 183.2 mm SL. Coloration in live specimen. Photograph by A.
Ortega-Lara.
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7
Y. A. Rojas-Molina, F. Provenzano-Rizzi & H. Ramírez-Gil
Fig. 5. Map of northern South America (Colombia and Venezuela) showing capture localities of Pseudohemiodon unillano,
red star is type locality, some symbols may represents more than one lot.
Ecological notes. Pseudohemiodon unillano inhabits
rivers and flooded areas at altitudes ranging from 135 to
334 m asl, in areas with gentle slope (between 0 and 3
percent) and sandy or clay substrate. In waters from high
turbidity (316 mg/l total solids) to slightly clear, with pH
between 6.7 and 8.6, conductivity between 117.5 and 387
μS/cm, oxygen concentration between 0.9 and 8.76 mg/l,
with percentage of saturation between 20 to 83%, and
temperature between 25 and 30.7°C. In a sample carried out at
Guayuriba River, Colombia, Pseudohemiodon unillano was
captured with anostomids (Laemolyta taeniata, Leporinus
striatus), apteronotids (Apteronotus galvisi, A. albifrons,
Sternarchorhynchus roseni), characids (Creagrutus taphorni,
Gephyrocharax valencia, Hemibrycon metae ), crenuchids
(Characidium boavistae), heptapterids (Cetopsorhamdia
orinoco, C. shermany, Imparfinis pseudonemacheir,
Phenacorhamdia anisura, P. taphorni), loricariids (Farlowella
mariaelenae, Lamontichthys llanero, Chaetostoma formosae,
Pterygoplichthys gibbiceps, Spatuloricaria terracanticum).
Conservation status. According registers, P. unillano is
common and abundant species, with wide geographical
distribution. No specific threats are known, thus tentatively
is categorized as Least Concern (LC) according to the
International Union for Conservation of Nature (IUCN)
categories and criteria (IUCN Standards and Petitions
Subcommittee, 2017). On the other hand, type locality is
intensely affected by extraction of sand, gravel and boulders,
and deforestation of the riparian forest (Ajiaco-Martínez et
al., 2015), with negative impacts on local populations of P.
unillano.
Discussion
Our results indicate that Pseudohemiodon unillano n.
sp. unambiguously belongs to the subfamily Loricariinae,
tribe Loricariini, and Pseudohemiodon-group. The external
morphological characters that supports this conclusion are:
head and body very depressed, especially the caudal peduncle;
dorsal-fin opposite the pelvic-fins; adipose fin absent; ten
branched caudal-fin rays; orbital notch present; maxillary
barbel conspicuous; teeth few and small, but visible in both
jaws. Among genera included in the Pseudohemiodon-group,
the new species certainly belongs to Pseudohemiodon, share
more external characters and is more similar to species
included in it. Shared characters include: head triangular in
shape, with rounded anterior border; snout not projected;
teeth visible in both jaws; maxillary barbel reaching or
surpassing gill opening, but never extending to pectoral-fin
base. The external morphology in Rhadinoloricaria species
and Dentectus barbarmatus Martín Salazar, Isbrücker,
Nijssen 1982 are quite different; in dorsal view, head never
is triangular in shape, some species of Rhadinoloricaria have
the snout projected, the abdomen is partially covered, and the
maxillary barbel surpasses pectoral-fin base. Also, species of
both genera have buccal morphology very different to that
observed in Pseudohemiodon species (see Günther, 1869:
figs. 5-6; Martín Salazar et al., 1982: figs: 2-3; Isbrücker,
Nijssen, 1983: figs. 1-2; 1986b: figs. 1-3; Nijssen, Isbrücker,
1988: figs 2-10; Chang, Castro, 1999: figs 1-2). Species of
Crossoloricaria, Planiloricaria cryptodon (Isbrücker, 1971)
and Pyxiloricaria menezesi Isbrücker, Nijssen 1984 have
similar gross morphology, but in Planiloricaria cryptodon
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New Pseudohemiodon from the Orinoco River basin
the maxillary barbel reaches beyond the pectoral-fin base,
the lower lip surface is narrower, with longer barbels on its
border, and the upper jaw is edentulous (Isbrücker, Nijssen,
1986a: fig. 3). Pyxiloricaria menezesi has the anterior margin
of the branchiostegal membrane with a large, fleshy, wrinkled
flap, and a peculiar head shape (Isbrücker, Nijssen, 1984: fig.
4). Species of Crossoloricaria have the abdomen partially
covered with plates, with a single narrow series along the
midline, leaving naked areas at the sides (Sciuiltz, 1944: Pl:
12, fig. C; Isbrücker, 1979: figs. 18-19).
Additionally, as previously indicated by Provenzano
(2011), the new species and other examined Pseudohemiodon
species exhibit a particular pattern of the buccal morphology
and ornamentation as follows: maxillary barbel can extend to
anterior border of pectoral-fin base, but rarely surpasses it. Lip
surfaces, especially the lower lip, are covered with fleshy, soft
and thick papillae, sometimes little elongated. Lip borders have
soft, fleshy, elongated, cylindrical, and branched small barbels
or cirri, those at the center are smaller, mainly on border of
lower lip. Inside the mouth, at distal side of each premaxilla,
there are two or three, soft, fleshy, cylindrical, unbranched
small barbels, and behind and between premaxillary, just at
the center of the mouth roof, one small barbel, soft, fleshy,
cylindrical, unbranched and longer (Figs. 2, 3, 6). The species
of Crossoloricaria have a very similar buccal ornamentation
to species of Pseudohemiodon, but there are two soft, fleshy,
unbranched elongated small barbels, behind and between
premaxillary, just at the center of the roof of the mouth
(Fig. 6). Described buccal morphology or ornamentation and
some external morphological characters allow a more certain
identification of species belonging to Pseudohemiodon.
Original figures and descriptions, available images of type
specimens (Günther, 1868: fig. 7; Regan, 1904: pl. XX, fig.1;
Isbrücker, Nijssen, 1978: fig. 6, Morris et al., 2006), plus
available specimens of P. lamina and P. apithanos, indicate
that P. unillano seems to be closer to P. lamina, P. laticeps
and P. apithanos. These species have similar or almost
identical abdominal cover, i.e. abdomen completely covered
by irregular, medium to small sized plates. In P. platycephalus
and P. thorectes, the abdomen has a middle longitudinal series
of wide, rectangular plates (Kner, 1853; Isbrücker, 1975: fig.
2). The condition in P. amazonum is doubtful, the image of
holotype at ACSI database (Morris et al., 2006) shows the
abdomen partially covered, but Isbrücker (1975:90) indicates
the abdomen completely covered by small bony plates. The
color pattern of P. unillano is similar to P. lamina and P.
laticeps, but P. lamina has plates in front of gill openings and
the sides of the snout are somewhat concave. The original
description of P devincenzii is very brief and does not provide
distinctive characters. Additionally, no figures or images of
the holotype are known. Therefore, making a comparison
with P. devincenzii is somewhat prohibitive. Soriano Señoras
(1950) indicate that the shape of lips and the arrangement
and size of abdominal plates separate P. devincenzii from P.
laticeps. According to our analysis, these differences are not
conclusive. Without conclusive and confident data, taxonomic
status of P. devincenzii still remains uncertain. It is unlikely
that a species native to the Uruguay River basin could be the
same species that inhabits the Orinoco River basin. Based in
geographical distribution we conclude that P. unillano and P.
devincenzii are different.
The geographical distribution of P. laticeps, P. lamina, P.
apithanos and P. unillano n. sp. includes Parana-Paraguay,
Amazon and Orinoco rivers basins, therefore this provides
an excellent opportunity to propose a biogeographical
hypothesis of the sequence of events that resulted in the
separation of the three basins using the typology of the
phylogenetic hypothesis of these four species.
Finally, Isbrücker, Nijssen (1978) suggested that P.
laticeps may be present in the Pastaza River basin, Ecuador.
Preliminary observations of an ongoing project on the
species of Pseudohemiodon from Ecuador, indicate that
P. laticeps is not present in Ecuadorian tributaries of the
Amazon River basin.
Fig. 6. Detail of buccal ornamentation. a. Pseudohemiodon unillano, paratype, MBUCV-V-20148, 166.9 mm SL;
b. Crossoloricaria venezuelae, MBUCV-V-2175, 57.8 mm SL.
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Y. A. Rojas-Molina, F. Provenzano-Rizzi & H. Ramírez-Gil
Comparative material examined. Apistoloricaria condei:
Ecuador: MEPN 3041, paratype, 140.0 mm SL; Provincia Orellana,
río Aguarico, afluente del río Napo. Crossoloricaria bahuaja:
Perú: MUSM 9916, holotype, 115.9 mm SL; Departamento Madre
de Dios, Rio Tambopata. Crossoloricaria venezuelae: Venezuela:
MBUCV-V-16357, 24, 120.0-172.0 mm SL, Estado Zulia, río
Apón, cuenca Lago de Maracaibo. Dentectus barbarmatus:
Venezuela: MBUCV-V-7406. 3, 143.0-145.0 mm SL; Estado
Portuguesa, río Boconó, afluente río Portuguesa. Planiloricaria
cryptodon: Peru: MBUCV-V-33026 (ex. ANSP 182304), 3,
87.0-174.0 mm SL; Loreto, río Amazonas. Pseudohemiodon
lamina: Ecuador: MEPN 16771, 1, 169.4 mm SL; Provincia
Orellana, Río Tiputini, afluente del río Napo. Pseudohemiodon
apithanos: Ecuador: MEPN 18375, 1, 174.0 mm SL; Provincia
Sucumbíos, Río Aguarico, afluente del río Napo. Pyxiloricaria
menezezi: Brazil: MZUSP 26800, 90.1 mm SL, holotype of
Pyxiloricaria menezesi Isbrücker, Nijssen 1984; Estado Mato
Grosso do Sul, marginal lagoons at Transpantaneira highway.
Rhadinoloricaria laani: Venezuela: MBUCV-V-19332, 17, 92.8119.4 mm SL; Estado Apure, río Apure, afluente del río Orinoco.
Rhadinoloricaria sp.: Ecuador: MEPN 18664, 1, 114.4 mm SL;
Provincia Sucumbíos, Río Jivino Negro, afluente del río Napo.
Acknowledgments
We wish to thank the following institutions and persons
for their support and assistance provided for examination
of specimens under their care. Universidad de los Llanos ECOPETROL (Project N° 5211592). C. DoNascimiento,
J. Albornoz and A. Méndez, IAvH, Fish Collection, Villa
de Leyva, Colombia. S. Prada and A. Urbano, MPUJ, Fish
Collection, Bogota, Colombia. J. López-Castaño, Colombia. A.
Ortega-Lara, Cali, Colombia. R. Barriga-Salazar, MEPN, Fish
Collection, Quito, Ecuador. H. Ortega, L. Chumbe Nolasco,
MUSM, Lima, Peru. O. E. Castillo, MCNG, Fish Colletion,
UNELLEZ, Guanare, Venezuela. A. Marcano, MBUCV, Fish
Collection, Caracas, Venezuela. Thanks to D. Taphorn and two
anonymous reviewers for its useful comments and suggestions.
D. Taphorn kindly reviewed the English.
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Submmited December 12, 2018
Accepted June 11, 2019 by Marcelo Britto