Pseudohemiodon unillano, Rojas-Molina & Provenzano-Rizzi & Ramírez-Gil, 2019

Rojas-Molina, Yecid Andrey, Provenzano-Rizzi, Francisco & Ramírez-Gil, Hernando, 2019, A new species of whiptail armored catfish, genus Pseudohemiodon (Siluriformes: Loricariidae) from the Orinoco River basin, Llanos region of Colombia and Venezuela, Neotropical Ichthyology 17 (2), pp. 1-10 : 2-7

Pseudohemiodon unillano , new species

urn:lsid:zoobank.org:act:76D2CFB3-7E7E-44F2-A08F-31EA54B63398

Figs. 1-4 ; Tab. 1

Loricaria laticeps .— López-Rojas, Machado-Allison, 1975:52 [Bocono River, Venezuela].

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, 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. MCNG- 5925, 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, 142.2- 222.0 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. 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, 13- 15 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. 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 ). 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, 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 ).

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.

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 .

Figures

Fig. 1. Pseudohemiodon unillano, new species, holotype, IAvH-P 19034, 162.0 mm SL. Photograph by J. Lopez-Castaño.

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.

Fig. 4. Pseudohemiodon unillano, paratype, IAvH-P 19088, 183.2 mm SL. Coloration in live specimen. Photograph by A. Ortega-Lara.

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.

Tables

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