Research Article |
Corresponding author: Gastón Aguilera ( gaguilera@lillo.org.ar ) Academic editor: Nicolas Hubert
© 2024 Guillermo E. Terán, Alejandro Méndez-López, Mauricio F. Benitez, Wilson S. Serra, Sergio Bogan, Gastón Aguilera.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Terán GE, Méndez-López A, Benitez MF, Serra WS, Bogan S, Aguilera G (2024) Re-description of Xyliphius barbatus (Siluriformes, Aspredinidae), with comments on osteology and distribution. Zoosystematics and Evolution 100(3): 1085-1097. https://doi.org/10.3897/zse.100.121396
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The banjo catfish, Xyliphius barbatus, belongs to the Aspredinidae family and typically inhabits the main channels of medium to large rivers in the La Plata River basin. The mimetic coloration with the substrate and the benthic lifestyle likely contribute to the challenge of sampling this species, resulting in its underrepresentation in museums and ichthyological collections. In fact, the original description of X. barbatus was based solely on two specimens. Consequently, little is known about its osteology, distribution, and phylogenetic relations. In this work, these information gaps are filled and the distributional range for X. barbatus is extended to northwestern Argentina.
Banjo catfish, fossorial fishes, La Plata River basin, morphology, osteology
The family Aspredinidae is composed of 13 genera and 49 valid species (
Except for Xyliphius lepturus, all the species of the genus were described based on one to three specimens (X. lombarderoi, X. melanopterus, X. magdalenae and X. sofiae based on a single specimen; X. barbatus and X. anachoretes on two specimens; and X. kryptos on three specimens). These fishes are rare in inventories of fish fauna and consequently in museum collections. This sparse representation is due to several factors, including their mimetic coloration with the substrate, their benthic lifestyle, the infaunal habits of many species, and, most importantly, their specific habitat preferences. Indeed, these species live in the main channels of medium to large rivers, where sampling is difficult (
In Argentina, other aspedinids have been recorded: Amaralia oviraptor Friel & Carvalho, 2016, Bunocephalus doriae Boulenger, 1902, Pseudobunocephalus iheringii (Boulenger, 1891), Pseudobunocephalus rugosus (Eigenmann & Kennedy, 1903), and Pterobunocephalus depressus (Haseman, 1911). Although the upper section of the Bermejo River basin has many endemisms (e.g.,
New inventories made in the Bermejo River basin have revealed the presence of Xyliphius barbatus, a species not previously recorded for the area. This record is the largest known batch regarding the species. The aim of this contribution, is to provide an accurate re-description of X. barbatus.
Specimens were collected by electrofishing and hand nets, euthanized by immersion in tricaine methanesulfonate (MS222), fixed in 10% formalin solution, and transferred to individual batches in a 70% alcohol solution. The material was deposited in ichthyological collections. In some fresh individuals, a small tissue sample was taken and immediately preserved in absolute ethanol for genetic analysis. The tissue aliquots were deposited in the tissue collection of CIT-FML. The study complied with the animal welfare laws, guidelines, and policies of the Comité Nacional de Ética en la Ciencia y Tecnología, Argentina. Collection permits were granted by the Ministerio de Ambiente of Jujuy. (permits’ numbers: 1103-306-M/2016, Res. N° 137/2016-MA).
Point to point measurements were taken with a digital caliper to the nearest 0.1 mm and expressed as percentage of the standard length (SL), except for subunits of head, expressed as percent of the head length (HL) (see Table
Morphometric data of Xyliphius barbatus. SD= standard deviation. Holotype (MLP 6798), Paratype (MLP 2799), Paraná River (MACN-Ict 6791. 5 ex.) Bermejo River specimens (CI-FML7944 and CFA-IC-12742 34 ex.).
Holotype | Paratype | Bermejo River (N= 20) | Paraná River (N= 5) | |||||
---|---|---|---|---|---|---|---|---|
mean | range | SD | mean | range | SD | |||
Standard length | 90.3 | 87.2 | 91.3 | 79.6 – 111.3 | 8.3 | 66.2 | 44.6 – 93.6 | 17.6 |
Percentage of SL | ||||||||
Body depth at dorsal – fin origin | 15.9 | 14.1 | 14.9 | 12.3 – 16.9 | 1.2 | 17.2 | 15.6 – 19.9 | 1.7 |
predorsal length | 42.6 | 40.4 | 40.4 | 38.3 – 45.2 | 1.4 | 41.7 | 40.0 – 43.0 | 1.1 |
prepectoral length | 26.6 | 25.6 | 25.8 | 23.6 – 28.4 | 1.1 | 27.2 | 25.8 – 28.9 | 1.2 |
prepelvic length | 47.3 | 45.8 | 44.0 | 41.0 – 49.1 | 1.7 | 45.9 | 43.2 – 51.8 | 3.5 |
preanal length | 63.9 | 63.2 | 60.3 | 58.2 – 64.1 | 1.4 | 60.9 | 58.0 – 63.9 | 2.4 |
caudal peduncle length | 26.2 | 23.2 | 27.7 | 25.0 – 31.1 | 1.8 | 26.6 | 24.4 – 29.6 | 2.0 |
caudal peduncle depth | 7.3 | 8.1 | 7.4 | 6.8 – 8.1 | 0.3 | 8.2 | 8.0 – 8.6 | 0.2 |
pelvic fin length | 14.9 | 12.6 | 14.1 | 12.6 – 15.2 | 0.8 | 15.5 | 13.3 – 16.6 | 1.3 |
anal – fin base | 13.3 | 11.6 | 14.3 | 12.7 – 16.6 | 1 | 13.2 | 11.6 – 15.5 | 1.5 |
caudal-fin length | 23.3 | 17.2 | 20.3 | 18.1 – 22.2 | 1.2 | 20.0 | 17.1 – 22.2 | 1.9 |
pectoral spine length | 16.8 | 16.6 | 15.5 | 13.8 – 17.2 | 0.9 | 17.2 | 15.0 – 19.5 | 2.0 |
humeral process length | 10.6 | 11.1 | 9.8 | 8.2 – 12.4 | 1.1 | 8.0 | 5.5 – 11.6 | 2.2 |
posterior process of coracoid length | 10.4 | 9.5 | 9.8 | 8.3 – 11.1 | 0.8 | 10.5 | 9.6 – 11.7 | 0.9 |
head length | 28 | 28.5 | 28.2 | 26.0 – 31.0 | 1.4 | 34.9 | 33.4 – 35.4 | 0.8 |
width at pectoral – fin insertion | 27.5 | 27.7 | 24.7 | 23.3 – 27.4 | 0.9 | 27.4 | 26.8 – 28.2 | 0.6 |
Percentage of HL | ||||||||
maximum head depth | 51.4 | 51.5 | 46.9 | 42.2 – 51.8 | 2.7 | 41.4 | 36.9 – 44.5 | 3.1 |
snout length | 35.4 | 25.9 | 33.0 | 29.7 – 39.9 | 2.4 | 25.1 | 21.8 – 29.2 | 2.8 |
eye diameter | 3.7 | 3.5 | 3.5 | 2.3 – 5.8 | 0.9 | 4.0 | 3.0 – 5.4 | 1.0 |
interorbital width | 30.1 | 24.9 | 30.6 | 27.3 – 35.8 | 2.2 | 21.7 | 19.7 – 23.8 | 1.8 |
maxillary barbel | 95.2 | 94.9 | 86.9 | 71.6 – 105.1 | 7.7 | 68.0 | 60.7 – 76.8 | 5.9 |
anterior to posterior nares distance | 11.2 | 8.4 | 10.7 | 7.6 – 16.5 | 2.1 | 11.3 | 7.3 – 14.3 | 3.4 |
posterior nare to orbit | 7.2 | 5.4 | 7.3 | 5.8 – 9.9 | 1.0 | 4.8 | 4.1 – 6.4 | 0.9 |
anterior internareal distance | 20.7 | 13.8 | 16.6 | 13.8 – 22.1 | 1.9 | 15.0 | 14.0 – 15.9 | 0.7 |
posterior internareal distance | 30.7 | 25.7 | 28.8 | 26.2 – 31 | 1.6 | 25.7 | 22.8 – 30.2 | 3.2 |
Total genomic DNA was extracted from ethanol-preserved muscle tissue of specimen CI-FML 7944 (tissue collection number: CIT-FML 00169), using a salt-based protocol (
List of sequences, with accessions and vouchers employed for molecular analysis.
Species | GenBank ID | Catalog | Basin |
---|---|---|---|
Xyliphius barbatus | OQ539436 | CI-FML 7944 | Bermejo River. Argentina |
Xyliphius barbatus | KU288948 | MG ZV-P 355 | Paraná River. Argentina |
Xyliphius lepturus | MF489386 | AUM46757 | Amazon River, Peru |
Xyliphius magdalenae | MF489382 | ANSP192845 | Magdalena River, Colombia |
Xyliphius melanopterus | MF489383 | MUSM36715_AP12 | Amazon River, Peru |
Xyliphius melanopterus | MF489384 | MUSM36715_AP28 | Amazon River, Peru |
Xyliphius melanopterus | MF489385 | STRI01784 | Amazon River, Peru |
Xyliphius sofiae | KU736764 | ANSP 182322 | Amazon River, Peru |
Collection’s acronyms:
All from Argentina: MLP 6798. Holotype. 90.3 mm SL. Paraná River at Rosario, Santa Fe province. Col. C. Vidal. MLP 2799. Paratype. 87.2 mm SL. Paraná River at Rosario, Santa Fe province. Col. R. Ringuelet. MACN 6791. 5 ex, 44.6–93.6 mm SL. Paraná River near Curtiembre, border between Santa Fe and Entre Rios provinces. 31°27'18.34"S, 60°10'11.95"W. 35–45 m depth 1961–1962 Col. N. Bellisio. MG-ZV-P 355 (LAR-254). 1 ex, 99.1 mm SL. Paraná River in front of Rosario, Entre Rios province, Argentina. 32°55'58.8"S, 60°37'58.8"W. 6 m depth. 04/03/2013 Col. Julián Aguilar. CI-FML 7944. 29 ex (3 C&S), 79.6–111.3 mm SL. CFA-IC-12742, 5 ex. 79,7–99,2 mm SL. San Francisco River, Bermejo River basin, Jujuy province; 23°50'27.08"S, 64°37'24.70"W, ca. 370 m asl. 1–2 m depth. 30 Sep 2016. G.E. Terán, G. Aguilera and D. Delgado.
Xyliphius barbatus is distinguishable from the remaining species of genus by the following combination of characters: (1) seven to 11 retrorse dentations on posterior margin of pectoral-fin spine (vs. six in X. anachoretes and four or five in X. magdalenae); (2) 24 to 30 dendriform papillae on inferior lip (vs. 20–22 in X. magdalenae, 30 in X. sofiae, and 22 to 27 triangular papillae, with only the lateral ones branched in X. kryptos); (3) I,3 or I,4 dorsal-fin rays (vs. I,5 in X. lepturus and X. melanopterus); (4) absence of dorsal pale band from snout tip to caudal-fin origin (vs. presence in X. anachoretes, X. magdalenae and X. melanopterus); (5) absence of a latero-dorsal band following the second row of tubercles on anterior part of body (vs. present in X. magdalenae and X. melanopterus); (6) eyes present and reduced (vs. absent in X. sofiae); (7) five to eight anal-fin rays (vs. nine in X. lepturus).
The additional characters that distinguish Xyliphius barbatus from the remaining species of the genus are: papillae dendriform on lower lip with large branches (vs. papillae with minute branches on X. anachoretes); three dorsal procurrent rays (vs. two in X. anachoretes, four to five in X. lepturus, and four in X. magdalenae); pelvic fin not reaching anal-fin origin (vs. just reaching in X. magdalenae); maxillary barbel surpassing pectoral-fin spine insertion (vs. not quite reaching pectoral in X. magdalenae); four branchiostegal rays (vs. five in X. sofiae); and two ossified proximal radials on pectoral fin (vs. one in X. sofiae).
Morphometric data is summarized in Table
Head triangular with a rounded snout. Eyes reduced (Fig.
Head, trunk, and fins are all covered by thick skin, while the skin in the ventral area and at the fin insertions is thinner. Trunk covered by unculiferus tubercles, which are more concentrated in the head. Five lateral rows of large tubercles extending from post-cephalic region to caudal-fin base, and concentrated in mid-dorsal line.
Dorsal-fin I,2,i (1) or I,3,i (33*), spine feeble. Dorsal-fin insertion on anterior half of body, closer to snout tip than to caudal-fin insertion, anterior to pelvic-fin insertion; shape triangular, rays elongated beyond the membrane. Anal fin i,3,i(1), ii,3,i(6), iii-3,i(7), ii-4,i(16*), iii-4,i(1), ii-5,i(3), ovoid, first branched anal-fin ray longest. Anal-fin insertion on the posterior half of body, closer to caudal-fin insertion than to snout tip. Pectoral-fin I,4,i (34*), its origin almost at half way between snout tip and dorsal-fin origin, and its distal tip reaching pelvic-fin origin. Distal tips of branched rays elongated beyond membrane. Pectoral spines thick, with seven to 11 developed retrorse serrae along posterior margin; spine capped by a fleshy elongation. Pelvic fin i,3,i (1) or i,4,i (33*), origin just posterior to vertical through dorsal-fin origin. The tip of pelvic-fin rays elongated throughout the membrane. Caudal fin i,4/4,i (34*), The ventral-most three branched caudal-fin rays longer.
Osteology
(Figs
Mesethmoid deep, slightly longer (anteroposteriorly) than wide, with an anterior notch separating two anterior wings. Premaxillae articulating on a ventrolateral concavity of mesethmoid, not visible in dorsal view due to a dorsal lamina. Two diverging laminae articulating dorsally with frontals by interdigitations. Lateral ethmoids articulate with frontals through a dorsal interdigitated process and medially with orbitosphenoid by cartilage; the latter covered ventrally by a laminar extension of the same bone articulating with parasphenoid; projecting lateral process joined to autopalatine at its middle length; ventrally flattened and extensively articulating with parasphenoid posteromedially. Frontals about 3.5 times longer than wide, their posterior wing articulating with supraoccipital, and lateral posterior margins enclosed by anterior extension of sphenotic. Anterior fontanel about 1.4 times larger than posterior one, synchondral articulation between lateral ethmoids and mesethmoid completely visible through fontanel. Supraoccipital enclosing almost half of posterior fontanel. Epiphyseal bar with a strong suture, its length equal to or greater than that of posterior fontanel. Supraoccipital a little longer than wide, extensively articulating with pterotic laterally, and with epioccipital posterolaterally; a notch in posterior region receiving the ascending process of posttemporal-supracleithrum; posterior process wide and short, in contact with dorsal portion of complex vertebrae. Sphenotic pitted; ventral surface with greater pores, sutured to pterotic laterally, leaving a posterior space with same bone in ventral view, with extensive anterior synchondral articulation with hyomandibula, sutured medially to parasphenoid and posteriorly to anterior lamina of prootic. Dorsal prootic covering lateral surface of frontals and with posterior articulation with supraoccipital. Pterotic with anterior lamina sutured to sphenotic, a concavity after its contact with suprapreopercle, and a lateral rounded expansion reaching opercle ventrally; contacting posttemporal-supracleithrum lateral arm at its posteriormost region. Epioccipital articulating anterolaterally with pterotic, medially with supraoccipital and dorsally with posttemporal-supracleithrum. The latter bone with dorsal process reaching lateral surface of supraoccipital over epioccipital; a ventral pointed process contacting posterior expansion of pterotic and posterior arm of the bone sutured to complex vertebra. Wider portion of parasphenoid at its articulation with sphenotic, extended to middle bassioccipital at its posterior end. Prootic visible only in ventral view, anterior lamina over sphenotic cartilage, extensively contacting parasphenoid medially, and sutured to pterotic posterolaterally, leaving to an anterior space with the same bone. Exoccipital bearing two projections enclosing posterior parasphenoid, strongly sutured to posteromedial edge of prootic, to exoccipital laterally and with complex vertebra by interdigitations. Basioccipital sub triangular, with a large foramen on its posterior half, a conspicuous pore anteromedially and additional ones laterally.
Skull of Xyliphius barbatus CI-FML 7944. A. Ventral view; B. Dorsal view. ach: anterior ceratohyal; ang: anguloarticular; anp: anterior nuchal plate; br: branchiostegal rays; cl: cleithrum; co: scapulocoracoid; den: dentary; dfr: dorsal fin rays; epo: epioccipital; ex: extrascapular; fro: frontal; gch: gas bladder chamber; hyo: hyomandibula; io1: infraorbital 1; iop: interopercle; iot: infraorbital tubules; lal: lateral line tubules; let: lateral ethmoid; mc: mandibular canal tubules; mes: mesethmoid; max: maxilla; na: nasal; op: opercle; pal: autopalatine; pch: posterior ceratohyal; pfr: pectoral-fin rays; pmx: premaxilla; pnp: posterior nuchal plate; po: preopercle; ps:pectoral-fin spine; pto: pterotic; pv5: parapophysis of vertebra five; qua: quadrate; rad: pectoral-fin radial; rb1: first rib; soc: supraoccipital; sc: posttemporal-supracleithrum; spo: sphenotic; sup: suprapreopercle; uh:urohyal; vh: ventral hypohyal. Scale bar: 1 mm.
Premaxillaries dorsomedially flattened and oval, in contact with ventrolateral notches of mesethmoid and separated by the latter. Premaxillary teeth absent. Maxillary tubular, with furrowlike opening on ventral surface; its condyle attached to anterior palatine cartilage. Dentary long and slender, laminar posterior region overlapping anterior face of angular; teeth conical and pointed inwards, arranged in two rows, the outer one with 3 to 5 teeth near the symphysis, and the inner row with 11–12 teeth; coronomeckelian absent. Meckel’s cartilage somewhat conical, wider laterally from its origin at angular, and slender medially at its joining with the dentary, which is located ventral to (or a little displaced medially) dentary dorsolateral notch.
Dorsal view of the neurocranium of Xyliphius barbatus CI-FML 7944. mes: mesethmoid; io1: infraorbital 1; na: nasal; max: maxilla; fro: frontal; spo: sphenotic; soc: supraoccipital; pto: pterotic; epo: epioccipital; sc: supracleithrum; cv: weber camara; gch: gas bladder chamber; pv5: parapophysis of vertebra five. Pores of the cephalic sensory lateral system s1 to s6 represent the pores from the supraorbital canal and i1 to i6 from the infraorbital canal. Scale bar: 2 mm.
Hyomandibula in dorsoventrally oblique position with respect to neurocranium; dorsalmost edge under anterior extension of sphenotic, followed by a synchondral articulation with the same bone; anterior cartilage contacting quadrate and extended to lateral portion of metapterygoid. Preopercle on lateral portion of hyomandibula, sutured to quadrate on its synchondral articulation with the same bone. Quadrate condyle anteroventrally oriented, to anguloarticular. Metapterygoid square, a little larger than endopterygoid, with a posterior concavity for the anterior lamina of hyomandibula. Endopterygoid ventral to posterior third of autopalatines, at posteroventral concavity of lateral ethmoids after its projecting lateral process, bearing a lateral pointed projection reaching autopalatine middle cartilage.
Anal, caudal and pelvic fins of Xyliphius barbatus CI-FML 7944. A. Anal-fin and pterygiophores; B. Caudal complex and fin; C. basipterygium. afr: anal-fin rays; apt: anal-fin pterygiophores; cfr: caudal-fin rays; dlw: dorsolateral wing of basipterygium; dpr: dorsal procurrent rays; nsp: neural spines of vertebrae 15 to 18; pcb: posterior cartilage of basipterygium; pfr: pelvic-fin rays; vpr: ventral procurrent rays. Scale bar: 1 mm.
Autopalatines with expanded anterior and posterior edges, its narrower portion anterior to lateral ethmoids cartilage. Opercle medially articulated with lateral arm of hyomandibula, anteriorly expanded and sutured with interopercle; posterior pointed projection reaching ventral expansion of pterotic. Interopercle accompanying ventralmost edge of opercle, its anterior pointed projection over posterior ceratohyal, covering the interhyal articulation from lateral view.
Urohyal subtriangular, with a medial longitudinal cleft on anterior corner and posterolateral developed wings. Two basibranchials, the anterior one about twice larger, contacting first hypobranchial anteriorly and second hypobranchial cartilage posterolaterally; posterior one reached by third hypobranchial. Only the first hypobranchial ossified with wider distal portion. Hypohyals squarish, narrow in its proximal region, and articulated to ceratohyal synchondrally. Ceratohyals with posteroventrally expanded lamina at the articulation with banchiostegal rays; dorsal and ventral extensions over cartilage with posterior ceratohyal sutured to anterior extensions of same bone. Posterior ceratohyal rectangular, with a notch anterior to posterodorsal corner at the articulation with interhyal. Branchiostegal rays four, lateral ones thicker and with more developed lamina, first one (medial) between posterior urohyal and lateral to corner of ceratohyal expanded lamina, the remaining ones associated with anterior ceratohyal cartilage, lateral-most at the articulation cartilage of ceratohyals. Interhyal present, articulated to posterodorsal ceratohyal, with lateral portion of hyomandibular and quadrate.
Ceratobranchials five, first two and last one (fifth) with a single series of small gill rakers, third and fourth with two series; fifth ceratobranchial bearing a dorsal drop-shaped plate with conical teeth, posterior portion long and slender, with four or five gill rakers. Five gill rakers on the anterior border of first and second ceratobranchials, one in the cartilage with first epibranchial; only epibranchials one to three with gill rakers, first with single row and the remaining two with double row of one or two gill rakers restricted to proximal portion. Epibranchials four, an uncinated process on the third one. Third pharyngobranchial thicker at its articulation with cartilage of third epibranchial; fourth pharyngobranchial about half of the latter and located dorsal to an oval tooth plate.
Nasal separated in two tubular ossifications by supraorbital sensory pore s2, posterior tubular ossifications of the supraorbital canal enters frontal just lateral to its articulation with mesethmoid posterior projection. Antorbital present, small, its canal piercing base of dorsal projection of infraorbital 1 and exiting posteriorly. First infraorbital over anterior cartilage of autopalatine, with notch bordering maxillary condyle; anteromedial projection pointed and curved, limiting the anterolateral portion of nares. Posterior infraorbitals as a small series of ossicles entering sphenotic canal laterally; ventral branches of i5 and i6 ossified.
Supraorbital sensory canal with pores s1-s2 and s2-s3 separating nasal in two tubular ossifications. Pore S4 opening at anterior frontal fontanel, s5 is missing and s6 opening at posterior frontal fontanel. Infraorbital sensory canal composed of six pores, the first and second ones opening at inner margin of infraorbital 1, and the third at outer margin. Pores i4 to i6 arranged in an arch reaching up close to anterior half of sphenotic.
Tubular series of preopercle mandibular canal initiating below posterior portion of dentary and separated by those joined to preopercle by a gap just lateral to quadrate condyle. Suprapreopercle as a small tubular canal between hyomandibula and pterotic, with dorsal and ventral laminae present. Extrascapular present. Lateral line complete, beginning at posterolateral exit of posttemporal-supracleithrum canal.
Dorsal lamina of Weber apparatus reaching dorsal surface, with flattened and slender process almost reaching nuchal plate posteriorly. The latter rhomboid in dorsal view, with a ventral lamina reaching neural processes of sixth vertebra. Posterior nuchal plate with two slender and pointed anterolateral projections joined to first rib by a ligament, ventrally contacting anterior plate. Gas bladder chamber evident from dorsal view, posteroventral portion partially enclosed by an anteriorly directed ventral lamina. Parapophyses of fifth vertebra reaching lateral wall of body, continuous with posterolateral edge of cleithrum; extensively joined to posterior region of complex vertebrae and covering its lateral border. Ribs six, first pair on sixth vertebra. Vertebrae 35, fist 30 or 31 bearing transversal lateral processes.
Pectoral spine retrorse serrations larger distally; first branched ray reaching end of spine or slightly beyond. Two proximal radials associated with the three proximal most rays; first branched ray associated with scapulocoracoid cartilage. Cleithrum dorsomedial pointed projection entering cavity formed by ventral posttemporal-supracleithrum and lateral lamina of complex vertebra; dorsolateral arm with a proximal pointed projection lateral to posttemporal-supracleithrum and rounded edge; medial arm anteriorly concave, bearing an extensive contact scapulocoracoid posteriorly, and sutured to contralateral cleithrum in larger C&S specimen (102.58 mm SL). Coracoids strongly interdigitated medially, their posterior processes passing base of last pectoral-fin rays and reaching vertical through dorsolateral arm of cleithrum. Pelvic fins not reaching anal-fin origin. Basipterygia with developed dorsolateral wings and lateral cartilage present; medial cartilage not reaching posterior medial margin of bone, which bear jagged borders; posterior cartilage short. First anal-fin pterygiophore reaching posterior portion of vertebra 15 and posterior anal-fin pterygiophore at posterior portion of vertebra 21. Caudal fin with five principal rays on both lobes, three dorsal and four or five ventral procurrent rays.
Coloration
(Fig.
Ground of body dark brown to black, head light brown, pectoral region lighter than dorsal region. A barely evident light brown middorsal stripe on head from snout tip to the middle of caudal peduncle, interrupted at dorsal-fin base. Lateral rows of tubercles brown, lighter than the background. Maxillary barbels dark brown with lighter tips; the remaining barbels light brown. Pectoral fins black with whitish tips; anal fin black with distal half whitish; all the other fins black with the distal third whitish. After the fixation process, the color tends to become paler brown, and the white portions on the fins are less noticeable (Figs
Molecular comparison employing the COI sequence (see Table
Including the new record from the San Francisco River, upper Bermejo River basin, Jujuy province and the previous records from the Paraná River, in Rosario (Santa Fe province), and in Chaco province (locality of X. lombarderoi), together with the records from the Paraguay River basin in Paraguay reported by
Most of the records of this species are from the main channel of big rivers and were collected by trawl nets from the bottom of Parana River at 35–40 m depth (MACN 6791). The specimens from the San Francisco River (Fig.
The global conservation status of Xyliphius barbatus was evaluated in 2021, being considered as Near Threatened under criteria B2a by the IUCN Red List of Threatened Species (
However, evaluations for this species should be made with caution because it has relatively few records and inhabits areas that are difficult to sample. Additionally, there is no information available on its population structure or density throughout its range.
See Suppl. material
In this contribution we report the northwesternmost record of Xyliphius barbatus in Argentina, more than 750 km from the previously distribution record of the species. According to
The scarcity of material has led to biased descriptions, since variations in morphology and meristic counts have not been considered, making it difficult to establish comparisons among species. This situation was also highlighted by Figuereido and Britto (2010) in the description of Xyliphius anachoretes; the authors considered that any inferences concerning the direction of change in the number of papillae from lower-lip is speculative and premature due to the absence of comparative material.
The specimens of Xyliphius barbatus collected in the upper Bermejo River represent the largest known batch for the species and one of the largest for the genus. Other numerous collections of aspredinids were made under special conditions. For example, when a river section was dried 70 exemplars of Hoplomyzon sexpapilostoma
From a genetic perspective, maximum likelihood analysis identified two main groups: one comprising Xyliphius lepturus and X. sofiae, and the other including X. magdalenae, X. barbatus, and X. melanopterus. This tree topology aligns with the morphological inferences made by
Additional similarities in the complex vertebra between Xyliphius melanopterus and X. barbatus were previously indicated by
Neither
In this work, an accurate re-description of Xyliphius barbatus based on osteological observations, morphometry, meristic counts and molecular data is provided. The distributional range of this species is widened to the upper Bermejo River basin in northwestern Argentina, more than 750 km in straight line from the previously known record of the species in the country. A provisional phylogenetic molecular hypothesis is provided in which the close relation with X. melanopterus is observed.
We extend our gratitude to Tiago Carvalho for reviewing the manuscript and making invaluable comments on Xyliphius species, which significantly enhanced the quality and accuracy of this paper. Pablo Pereyra (FML) made figures 4 and 6. We thank Gustavo Chiaramonte (MACN), James Anyelo Vanegas-Rios (MLP), Diego Nadalin (MLP), Germán Saigo (MG), Eugenia Montani (MG) and Adrián Giacchino (CFA, UMAI) for the support provided and for making available the ichthyological collections of the respective institutions. GET and GA thank Diego Delgado for help in sampling trips. Julio Endler and Roberto Toval, for the photograph of specimens (Suppl. material
Informal records by anglers, with photograph evidence. Speciemens colleced with earthworm bait
Data type: docx
Explanation note: The information provided here represent records of Xyliphius barbatus capture by anglers in two localities algon the Paraná river, also including a map of these localities.
Comparative material examined
Data type: docx
Explanation note: In this file all reference material consulted in this work is listed.