Hypostomus pantherinus Kner 1854

Zawadzki, Cláudio Henrique, Carvajal-Vallejos, Fernando M., Silva, Hugmar Pains Da, Lechner, Walter & Penido, Iago De Souza, 2021, Assessing twohundredyearsoftaxonomicdoubt withtherediscoveryandtaxonomic establishment of the Amazonian armored catfish Hypostomus pantherinus Kner 1854 (Siluriformes: Loricariidae), Zootaxa 5067 (3), pp. 401-416 : 402-408

Hypostomus pantherinus Kner 1854

( Figs. 1 , 2 , 3 , 6 and 7 )

Hypostomus pantherinus Kner 1854: 267 . Type locality: Rio Guaporé, no more details [ohne nähere Angaben] [ Brazil]. Holotype: NMW 44206. Originally proposed as Hyp. pantherinus .— Regan 1904: 209 [listed as synonym of Plecostomus verres ].— Boeseman 1968: 16 [listed, speculative relationships].— Isbrücker 1980: 29 [listed, literature compilation]. Burgess 1989: 432 [listed, literature compilation].— Ferraris, 2007: 258 [listed, literature compilation].— Weber 2003: 361 [listed, literature compilation].— Carvalho & Bockmann 2007: 94 [listed, literature compilation].— Zawadzki et al. 2017:571 [diagnosed from H. velhochico ].—Froese & Pauli 2021 [word wide web electronic publication: literature compilation].

Diagnosis. Hypostomus pantherinus is distinguished from the species of the H. cochliodon group by having villiform teeth and angle between dentaries usually larger than 80° (vs. spoon- or shovel-shaped teeth and angle between dentaries about 80°); from H. coppenamensis , H. corantijni , H. crassicauda , H. gymnorhynchus , H. micromaculatus , H. nematopterus , H. paucimaculatus , and H. watwata by having roundish dark spots on the body (vs. usually transverse ellipsoid dark spots on the body, see Weber et al. 2012), and by having teeth bearing a short roughly rounded main cusp, with lateral cusp about half the length of the main cusp (vs. elongate main cusp with a usually small lateral cusp). Hypostomus pantherinus is diagnosed from the remaining congeners except H. affinis , H. ancistroides , H. argus , H. aspilogaster , H. borellii , H. boulengeri , H. carinatus , H. careopinnatus , H. cordovae , H. commersoni , H. delimai , H. dlouhyi , H. faveolus , H. formosae , H. gymnorhynchus , H. hemiurus , H. hoplonites , H. interruptus , H. niceforoi , H. nigrolineatus , H. piratatu , H. plecostomus , H. punctatus , H. pusarum , H. rhantos , H. scabriceps , H. seminudus , H. spiniger , H. subcarinatus , H. tapijara , H. velhochico and H. watwata , by having moderate keels along the five lateral series of plates (vs. lacking keels); from the species above except some specimens of H. carinatus by having sharp contrasting (strongly pigmented) and widely spaced black spots on a brown background (vs. somewhat faded—moderately pigmented—and close to moderate spaced dark spots); by having sharp crests on supraoccipital and pterotic-supracleithrum (vs. blunt crests); and by attaining smaller size, up to 158 mm SL (vs. usually presenting some specimens larger than this size); from H. carinatus , H. delimai , H. hoplonites , and H. watwata by having one single fused plate posteriorly bordering supraoccipital (vs. a set of plates ranging from four to ten plates, like a grape bunch). Hypostomus pantherinus is additionally diagnosed from H. plecostomus by having sharp crests on supraoccipital and compound pterotic-supracleithrum, compound pterotic-supracleithrum with less than 25 five dark spots, dorsal fin with one spot per row on each interradial membrane, and by attaining smaller size, up to 158.0 mm SL (vs. moderate or blunt crests on supraoccipital and on compound pterotic-supracleithrum, more than 25 dark spots, dorsal fin with two spots per row, and by attaining larger size, up to 250.0 mm SL).

Description. Morphometric and meristic data in Table 1 . Head stout and deep, moderately compressed. Head depth about 60% of cleithral width and cleithral region approximately equal to head length. Snout and anterior profile of head moderately pointed in dorsal view. Snout, in lateral profile, rising on straight line up to approximately 45º from snout tip to interorbital region, then convexly to dorsal-fin origin; from this point on, dorsal profile sloped downward from dorsal-fin origin to dorsal procurrent caudal-fin rays, then elevating again to caudal-fin origin. Ventral profile almost straight from snout tip to caudal fin. Caudal peduncle in cross-section from somewhat octogonal on its anterior portion to compressed posteriorly; flattened dorsally and ventrally. Eye small to moderate in size (15–20% of HL), laterally positioned. Interorbital area width moderate and flat in frontal view. Supraorbital raised. Mesethmoid forming conspicuous median ridge on snout dorsal region, mainly in smaller specimens. Sharp ridge on dorsal surface of head, from nare to upper margin of eye, and from this point transversely along dorsal portion of compound pterotic-supracleithrum ( Fig. 7a 1 ). Cheek plates with usually small odontodes; eventually, with slightly developed odontodes on posterior border of plates. Cleithral process deep and short in lateral view, usually as deep as long; its upper border usually convex; posterior border pointed. Supraoccipital generally with conspicuous sharp median ridge ( Fig. 7b 3 ); supraoccipital posterior process moderate to long and bordered posteriorly by first predorsal fused plate. Head dorsolaterally covered by dermal plates on snout and cheek regions, except small naked area on snout tip. Compound pterotic-supracleithrum also with crest. Predorsal region with strong pair of ridges, conferring flat aspect to its upper portion. Dorsolateral surface of trunk and caudal peduncle covered by five series of dermal plates, except thin naked area bordering dorsal-fin base. On trunk, dorsal series of plates keeled from dorsal-fin origin to two plates anterior to adipose-fin origin; plates around adipose-fin insertion and dorsal procurrent caudal-fin rays not carinate. Mid-dorsal and median series keels ending below adipose fin; remaining plates unkeeled on both series. Median series bearing lateral line. Median series conspicuously bent to its fifth plate; keeled until transverse line at dorsal-fin posterior border. Ventral series not keeled but bent to form caudal peduncle floor. All keels on lateral plates with horizontally and medially aligned, back-oriented hypertrophied odontodes; except third plate of mid-dorsal series with keel elevated up to 15°.

Mouth small comparatively to congeners. Lips short and round. Upper lip externally covered by platelets; internally fully covered with papillae; its border fringed or papilose. Lower lip far from reaching gill opening and covered with numerous small papillae, larger proximally. Maxillary barbel moderate in length, shorter to or similar in length to orbital diameter. Teeth thin, with elongate stalk and short crown. Tooth crown with short and round main cusp and smaller and pointed lateral cusp. Tooth crown curved inward about 50°. Intermandibular tooth row angle approximately 120°. Internally to mouth small and round papillae bordering both dentaries and maxillaries. Medial buccal papilla large, its tip blunt.

Lower surface of head mostly naked with small patch of plates anterior to gill openings in specimens up to 92 mm SL (USMM 1725); in larger specimens, lower surface of head almost totally covered by platelets except area just beneath lower lips. Scapular bridge and abdomen almost totally covered by platelets except two small areas just anterior to origin of pelvic fin. Preanal plate exposed, transversely ellipsoid.

Dorsal fin II,7; large, usually deeper than longer; its distal border convex. First dorsal-fin spine as V -shaped spinelet. Second dorsal-fin spine long and flexible. Posterior dorsal-fin branched rays usually reaching spine of adipose fin when adpressed. Adipose-fin spine well developed, curved inward, with distal tip usually one plate from anteriormost dorsal procurrent ray or just reaching it. Pectoral fin I,6; its distal border straight. Pectoral-fin spine straight to slightly curved, with rounded tip, and usually with slightly developed odontodes, most-developed on distal portion and in larger specimens; when adpressed almost reaching middle of pelvic-fin spine. Pelvic fin i,5; its distal border convex. Pelvic-fin unbranched ray curved inward; when adpressed reaching middle anal-fin insertion. Anal fin i,4; when adpressed, distal tip of posterior rays reaching fifth to sixth plate posterior to its origin. Caudal fin i,14,i, strongly emarginated. When intact, ventral caudal-fin unbranched ray longer than predorsal length. Caudalfin ventral lobe slightly longer than dorsal lobe.

Color in alcohol. Ground color of dorsal surface of head, trunk and fins brown; ventral lips, abdominal region and median ventral surface of caudal peduncle slightly lighter. Head, trunk and fins covered with dark, widelyspaced spots. Tiny dark spots on snout and cheek regions, slightly enlarging towards supraocipital and compound pterotic-supracleithrum and to dorsolateral surface of trunk and fins. Spots in general smaller than eye diameter.

Distance between spots usually enlarges caudally. On smaller specimens, dark spots fewer and relatively larger than those on larger specimens and more widely spaced (MCP 35963, 86.8 mm SL). Ventral surface of head, abdomen and caudal peduncle usually with inconspicuous round and widely spaced dark spots. Sometimes spots not visible on ventral surface of head and abdomen (MCP 35963 and NUP 17760). Dorsal-fin rows of spots ontogenetically increasing in number. In juveniles about three rows of dark spots. In adult specimens seven to eight transverse rows of conspicuous dark spots on dorsal fin, with one spot per interradial membrane along each row. Adipose-fin spine spotted. Caudal fin with five to eight transversally aligned row of inconspicuous dark spots. Caudal-fin usually with dark stripe bordering dorsal and ventral unbranched rays; wider and more conspicuous on ventral lobe. Pectoral and pelvic fins with six to seven irregular transverse line of dark spots on unbranched rays and on interradial membranes; usually with one spot per interradial membrane along each line ( Figs. 2 , 3 and 4 ).

Color in life. Similar to preserved specimens, except that color background more reddish brown and spots black ( Fig. 4 ).

Distribution, habitat and conservation status. Hypostomus pantherinus is known from upper and middle portions of rio Iténez-Guapore basin ( Fig. 5 ). The specimens of H. pantherinus are usually found in lentic waters, with substrate composed by particulate organic matter and trunks, in addition to a margin with aquatic macrophytes. The rio Iténez-Guaporé has clear waters, especially in its upper part, where there are some rapids and rocky environments, and in the dry period there is the formation of sand banks. But mainly it is a river with lentic environments and calm waters, with formations of areas of deposition of forest organic matter and sand coming from the agricultural and mining systems in the upper part ( Fig. 6a, 6b ). In the medium portion of the river, two landscape mosaics are observed in the Iténez-Guaporé watershed. The Bolivian side has large areas of forest cover with few anthropic impacts ( Fig. 6c, 6d ). On the other hand, the Brazilian landscape has large areas degraded by mining and agribusiness activities. Based on data available in this paper, H. pantherinus , with an estimated Extent of Occurrence (EOO) of ~ 42,000 km 2, would be assessed as Least Concerned (LC) according to IUCN criteria ( IUCN standards and petitions subcommittees 2019).

Figures

FIGURE 1. Hypostomus pantherinus, NMW 44206, 47.5 mm SL, holotype, in dorsal, lateral, and ventral views, rio Iténez- Guaporé, Brazil.

FIGURE 2. Hypostomus pantherinus, MNNH 99-12-0-18, 143.0 mm SL, in dorsal, lateral, and ventral views, rio Iténez- Guaporé, Boca Machupo, Bolivia.

FIGURE 3. Hypostomus pantherinus, AMNH 39946, 128.9 mm SL, in dorsal, lateral, and ventral views, rio Iténez-Guaporé, above mouth of rio Baures, near Costa Marques, Brazil in the divide with Bolivia.

FIGURE 4. Live specimens of Hypostomus pantherinus; a) uncatalogued juvenile specimen in lateral view from the medium stretches of the rio Iténez-Guaporé, with approximately 30 mm SL, upstream municipality of Costa Marques, Rondônia State, Brazil; b) NUP 17760, 107.4 mm SL, in dorsolateral view, rio Barbado, tributary of the upper rio Iténez-Guaporé, municipality of Vila Bela da Santíssima Trindade, Mato Grosso State, Brazil in the divide with Bolivia.

FIGURE 5. Distribution of Hypostomus pantherinus. Red star represents the putative locality of holotype and yellow circles the non-type specimens.

FIGURE 6. Typical habitats of Hypostomus pantherinus: a and b) upper rio Iténez-Guaporé near municipality of Pontes e Lacerda, Mato Grosso State, Brazil and; c and d) medium stretches of the rio Iténez-Guaporé at municipality of Costa Marques, Rondônia State, Brazil.

FIGURE 7. Head in dorsal and in lateral views with withe arrows showing: (a1) sharp crest on compound pterotic-supracleithrum and on (b3) supraoccipital in Hypostomus pantherinus, MNHN 9912028, 143.0 mm SL, rio Iténez-Guaporé, Boca Machupo, Bolívia; versus (c1 and d3) moderate crests in Hypostomus plecostomus, ZMA 105.023, 110.3 mm SL, Coppename river, Suriname; (a2) less than 25 spots on compound pterotic-supracleithrum in H. pantherinus and (c2) more than 25 spots in H. plecostomus.