Hypostomus carinatus (Steindachner 1881)

(Figs. 1, 2 and 3)

Plecostomus carinatus — Steindachner 1881: 108 [original description, pl. 4 (fig. 2). Type locality: Jatuarana, Ueranduba und aus dem See Saracca [lago Jatuarana, lago do Iranduba and from the Lago Saracá], Amazonas State, Brazil]. Types: MNW 44094 (1), 44096 (1).— Eigenmann & Eigenmann 1890:398 [identification key].

Hypostomus carinatus— Boeseman 1968: 16 [listed, literature compilation].— Goulding et al. 1988 [list of species].— Ferreira et al. 2007: 154 [live picture].— Ferraris 2007: 252 [listed, literature compilation].— Hercos et al. 2007: 44 [listed, literature compilation].— Weber 2003: 356 [listed, literature compilation].— Maldonado-Ocampo et al. 2008: 196 [listed, literature compilation].— Collins et al. 2015: 24 [brief comments and live picture].—Froese & Pauli 2019: 23 [brief comments].—de Queiroz et al. 2020: 7 [phylogenetic relationships].

Watawata carinata — Isbrücker et al. 2001: 23 [listed, generic realocation].

Diagnosis. Hypostomus carinatus is distinguished from all congeners, with the exception of H. delimai, H. hoplonites, and H. watwata by the presence of four to nine (mode seven) predorsal plates surrounding the parietosupraoccipital bone posteriorly (vs. one to three plates); it differs from H. delimai by having dark spots on body and fins (vs. pale spots); from H. hoplonites by having the dark spots smaller or almost equal to distance among each spot (vs. spots larger in size than the distance among spots) and by having body carenae with odontodes (vs. carenae heavily armored with median aligned huge odontodes on each dermal plate); and from H. watwata by having a compressed head with eyes laterally positioned (vs. depressed head with eyes dorsolaterally positioned), by having ventral unbranched caudal-fin ray smaller than preanal length (vs. longer than preanal length).

Description. Counts and measurements in Table 1. Head narrow and deep, compressed. Body width in cleithral region greater than head depth and approximately equal to head length. Snout and anterior profile of head weakly rounded in dorsal view. Snout, in lateral profile, rising on a straight line up to approximately 40º from snout tip to interorbital region, then strongly convex 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. Caudal peduncle somewhat octagonal in cross-section, flattened dorsally and ventrally. Eye large in size (14.4–18.2% of HL), laterally positioned. Interorbital space wide and flat to concave in frontal view. Mesethmoid forming conspicuous median ridge on snout dorsal region, mainly in smaller specimens. Strong ridge on dorsal surface of head, from nare to upper margin of eye, and from this point to dorsal portion of pterotic-supracleithrum. Cheek plates with odontodes usually small; eventually, well developed odontodes on posterior border of plates. Cleithral process high in lateral view, usually higher than longer; its upper border convexly rounded; ventral border concavely rounded. Parietosupraoccipital with very deep median bulge; parieto-supraoccipital process moderate to long bordered posteriorly by first predorsal pair of plates and laterally by a set of five to ten fragmented platelets. Dorsal and lateral surface of head and body covered with dermal plates, except for small naked patch on median tip of snout and dorsal-fin base. Predorsal region very deep, with pair of ridges conferring flat aspect to its upper portion. Trunk and caudal peduncle covered by five lateral series of dermal plates. 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 carenate. Mid-dorsal series keel ending three to four plates short caudal-fin base; remaining plates unkeeled. Median and mid-ventral series completely keeled. Median series bearing lateral line. Mid-ventral series strongly bent ventrally from urogenital opening to caudal peduncle end. Ventral series not keeled. All 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 moderate in size. Lips wide and round. Upper lip covered by platelets. Lower lip far from reaching gill opening and covered with numerous small papillae, larger proximally. Maxillary barbel moderate in size, slightly longer than orbital diameter. Teeth moderately robust, with short and round main cusp and smaller and pointed lateral cusp. Teeth crown curved inward. Intermandibular tooth row angle approximately 80° to 100°. Medial buccal papilla large, its tip papilose.

Lower surface of head totally covered by platelets except area just beneath lower lips. Scapular bridge and abdomen also totally covered by platelets except two small areas just ahead origin of pelvic fin.

Dorsal fin II,7; large, mainly concerning its base length; its border almost straight. Dorsal-fin spine flexible; reaching spine of adipose fin when adpressed. Adipose-fin spine well developed, curved inward, with distal tip usually one or two plates distant from anteriormost dorsal procurrent ray. Pectoral fin I,6; spine mostly straight to slightly curved with rounded tip, and usually with well-developed odontodes, most-developed on distal portion and in larger specimens; when adpressed reaching middle of pelvic-fin spine. Pelvic fin i,5; unbranched ray curved inward; when adpressed surpassing anal-fin insertion; its border slightly rounded. Anal fin i,4; when adpressed, distal tip of posterior rays reaching seventh or eighth plate posterior to its origin. Caudal fin i,7+7,i, strongly emarginated, with ventral lobe longer than dorsal lobe.

Color in alcohol. Ground color of dorsal surface of head, trunk and fins brown reddish; lips, abdominal region and median ventral surface of caudal peduncle slightly lighter. Head, trunk and fins covered with dark spots (Fig. 2). Spots on head small and densely packed, diameter similar to nostril aperture; on dorsal and ventral region of trunk spots gradually larger, diameter similar to eye pupil, and sparsely distributed. Black dots on younger specimens more distant from each other. Some specimens with five inconspicuous faded oblique dark bars on dorsum, the stress coloration, with first bar on posterior portion of head, originating at middle of orbit, second bar at first dorsal-fin branched rays, third bar at last dorsal-fin branched ray, fourth bar at anterior region of adipose-fin and fifth, at procurrent caudal-fin rays. Dorsal and anal fin with one line of spots on each interradial membrane; adi- pose-fin spine with spots; pectoral and pelvic fins with spots on unbranched and branched rays and on interradial membranes, sometimes aligned transversally; caudal fin with spines transversally aligned, lower lobe darker than upper lobe.

Color in life. Similar to preserved specimens, except by body and fins more reddish tan, particularly on fins, and spots black (Fig. 3a).

Distribution and conservation status. Hypostomus carinatus is widely distributed in the central portion of the Brazilian Amazon, in the main rivers and their tributaries. In the Amazonas State, there are records of H. carinatus in the Japurá, Juruá, Negro, Purus, Uatumã rivers and in the Nhamundá River on the border with Pará State. In the Pará State the species is found only in the Trombetas and Tapajós rivers. In Roraima State it was recorded in the Branco River and its tributaries, and in the Jauaperi River (Fig. 4).

Based on data available in this paper, H. carinatus, with an estimated Extent of Occurrence (EOO) of 813,631.840 km 2, is assessed as Least Concerned (LC) according to IUCN criteria (IUCN standards and petitions subcommittees 2017).

Remarks on type specimens. Steindachner (1881), in the H. carinatus description, cited that the Vienna Museum (NMW) owns specimens from the Amazon stream without specifying the location and the Cambridge Museum (MCZ) owns specimens from the Jatuarana [rio Jatuarana], Ueranduba [lago do Iranduba] and Lake Saraca [lago de Saracá]. However, the only H. carinatus specimen found by the first author in 2007 and also the only specimen registered in the MCZ fish collection database is MCZ 27266. Eigenmann & Eigenmann (1890) stated that they were unable to find the specimens cited by Steindachner for the MCZ. Additionally, the specimen MCZ 27266 is labeled as a syntype of P. carinatus at MCZ, but although indeed being from the Thayer Expediction, the specimen locality, the rio Jutaí, is not in Steindachner’s description. Therefore, the specimen MCZ 27266 cannot be considered a type of P. carinatus. On the other hand, although Steindachner wrote that the specimens from NMW had uncertain locality, the two lots, NMW 44094 and NMW 44096, indeed bear locality information on their labels. MNW 44094 is labeled as being from Silves, Saraca [lago Saracá in the ilha de Silves] and the lot MNW 44096 is labeled as being from Ueranduba [lago do Iranduba] and they are the only types of P. carinatus available. Data on the ichthyological collection sites of the Thayer Expedition to Brazil (1865-66) were extracted from Dick (1977) and Higuchi (1996).

Material examined. All from Brazil. Rio Amazon basin.

Type specimens. NMW 44094, 1, 219.6 mm SL, lectotype by present designation, Amazonas State, Silves (ilha de Silves), lago Saracá, approx. 2°50’20”S 58°12’33”W, Dec 1865, S. V. R. Thayer. NMW 44096, 1, 251.8 mm SL, paralectotype by present designation, Amazonas State, Manaus, Iranduba, lago do Iranduba, aprox. 3°14’25”S 60°3’17”W, Major M. Coutinho, Nov-Dec 1865.

Non-type specimens. Amazonas State: MCZ 27266, 1, 230.0 mm SL, labeled as a syntype in MCZ collection but although being from the Thayer Expediction, this locality is not in Steindachner’s description, Jutaí, rio Jutaí, tributary of rio Solimões, approx. 2°44’50”S 66°46’48”W, Sep-Oct 1865, W. James & S. V. R. Thayer & “Talisman”. INPA 527, 3, 206.5 –256.0 mm SL, Novo Airão, rio Negro, arquipélago de Anavilhanas, 2°44’37”S 60°44’36”W, 7 Feb 1984, J. C. Malta. INPA 1194, 10, 186.2 – 264.7 mm SL; NUP 21240, 3, 231.8 – 245.5 mm SL,

Novo Airão, rio Negro, arquipélago de Anavilhanas, lago do Prado, 2°44’10”S 60°42’43”W, 1 Oct 1980, M. Goulding. INPA 1995, 1, 179.8 mm SL, Novo Airão, rio Negro, arquipélago de Anavilhanas, margem da ilha, 2°44’37”S 60°44’36”W, 10 Dec 1980, M. Goulding. INPA 2533, 2, 220.7 – 279.2 mm SL, Presidente Figueiredo, Santa Luzia, rio Uatumã, 2°18’8”S 58°30’13”W, 12 Sep 1985, M. Jégu. INPA 2534, 2, 177.7 – 236.7 mm SL, Presidente Figueiredo, Nazaré, rio Uatumã, 1°32’14”S 60°0’48”W, 12 Nov 1985, S. Amadio. INPA 2535, 1, 182.6 mm SL, Presidente Figueiredo, córrego Água Branca, 30 Apr 1985, S. Amadio. INPA 2536, 2, 187.2 –241.0 mm SL, Presidente Figueiredo, Nazaré, rio Uatumã, 1°32’14”S 60°0’48”W, 11 Jul 1987, S. Amadio. INPA 2537, 1, 212.3 mm SL, Presidente Figueiredo, córrego Arraia, tributary of rio Uatumã, 2 Nov 1985, S. Amadio. INPA 2538, 2, 222.3 mm SL, Presidente Figueiredo, córrego Arraia, tributary of rio Uatumã, 1 Sept 1985, M. Jégu. INPA 2539, 1, 234.3 mm SL, Presidente Figueiredo, Rio Uatumã, ilha de Nazaré, 1°32’14”S 60°0’48”W, 02 Sept 1985, M. Jégu. INPA 2540, 2, 207.0– 272.9 mm SL, Presidente Figueiredo, córrego Samaúma stream tributary of rio Uatumã, 31 Sept 1985, S. Amadio. INPA 2541, 1, 192.8 mm SL, Presidente Figueiredo, córrego Arraia, tributary of rio Uatumã, 1 Nov 1985, S. Amadio. INPA 2542, 1, 231.5 mm SL, Presidente Figueiredo, córrego Arraia, tributary of rio Uatumã, 1 May 1985, S. Amadio. INPA 2543, 1, 182.7 mm SL, Presidente Figueiredo, córrego Água Branca, tributary of rio Uatumã, 1 Nov 1985, S. Amadio. INPA 6180, 2, 181.7 – 214.8 mm SL, Presidente Figueiredo, córrego Arraia, tributary of rio Uatumã, 26 Jan 1985, Eq. de Ictiologia do INPA. INPA 6181, 1, 220.3 mm SL, Presidente Figueiredo, ilha de Nazaré, rio Uatumã, 1°32’14” S 60°0’48”W, 1 Feb 1985, Eq. de Ictiologia do INPA. INPA 6182, 2, 217.4 – 236.9 mm SL, Presidente Figueiredo, córrego Miriti, tributary of rio Uatumã, 2°1’44”S 59°26’23”W, 7 Feb 1985, S. Amadio. INPA 6183, 6, 177.0– 297.3 mm SL, Presidente Figueiredo, rio Uatumã, 10 Mar 1985, Eq. de Ictiologia do INPA. INPA 6184, 2, 256.5 – 260.6 mm SL, Presidente Figueiredo, rio Uatumã, 15 Apr 1985, Equipe de Ictiologia do INPA. INPA 6213, 1, 204.4 mm SL, Novo Airão, rio Negro, Arquipélago de Anavilhanas, 2°44’37”S 60°44’36”W, 4 Mar 1978, Equipe de Ictiologia do INPA. INPA 6485, 3, 209.9 – 228.6 mm SL; NUP 21241, 3, 176.7 – 215.9 mm SL, Presidente Figueiredo, igarapé do Arraia, 31 Oct 1984, Equipe de Ictiologia do INPA. INPA 6487, 1, 235.1 mm SL, Presidente Figueiredo, rio Uatumã, Balbina, 1°55’4.68”S 59°28’22.3”W, 30 Sep 1983, Equipe de Ictiologia do INPA. INPA 9936, 1, 239.6 mm SL, Novo Airão, rio Jaú, lago Miratucu, 1°52’13”S 61°38’22”W, rio Negro basin, 29 Oct 1994, M. Garcia & A. Oliveira. INPA 15164, 1, 180.8 mm SL, Presidente Figueiredo, rio Uatumã, pé da barragem, 1°55’4”S 59°28’22”W, 26 Oct 1987, J. Zuanon, S. Amadio & C. de Deus. INPA 17946, 1, 211.93 mm SL, São Gabriel da Cachoeira, rio Negro, 0°09’37”S 67°05’14”W, 18 May 1975, M. Goulding. INPA 19567, 1, 203.5 mm SL, Maraã, lago Amanã, mouth of córego Uxi, 2°37’31”S 64°39’53”W, rio Japurá basin, 14 Dec 1997, W. Crampton. INPA 23700, 1, 190.8 mm SL, Beruri, rio Preto do Igapó-Açú, RDS Igapó-Açú, 4°43’1”S 61°25’5”W, rio Purus drainage, 19 Oct 2013, T. Couto, G. C. Barros & V. Machado. INPA 26853, 1, 250.0 mm SL, Presidente Figueiredo, rio Uatumã, cachoeira Morena, 2°7’23”S 59°19’49”W, 12 Dec 2005, E. G. Ferreira. INPA 27384, 1, 265.3 mm SL, Presidente Figueiredo, rio Urubu, Cachoeira Lindóia, 30 Sep 1983, E. Ferreira. INPA 31836, 2, 255.3 – 265.8 mm SL, Novo Airão, rio Ariau, Arquipélago de Anavilhanas, rio Negro, 28 Feb 1976, Eq. de Ictiologia do INPA. INPA 32103, 1, 89.8 mm SL, Novo Airão, rio Negro, Arquipélago de Anavilhanas, margem das ilhas, 31 Oct 1980, M. Goulding. INPA 32944, 1, 239.0 mm SL, Carauarí, RDS Uacari, igarapé Anaxiqui, rio Jaruá, 5°49’2”S 67°55’12”W, 17 Oct 2008, P. Farias. INPA 32948, 1, 215.3 mm SL, Carauarí, RDS Uacari, igarapé Anaxiqui, 5°48’11”S 67°55’8”W, 22 Oct 2008, P. Farias. 33861, 2, 199.5– 265.8 mm SL, Novo Airão, Archipelago of Anavilhanas, margin of igapó forest, 02 Oct 1980, M. Goulding. INPA 37253, 2, 197.6 – 217.4 mm SL, São Sebastião do Uatumã, ressaca do rio Jatapu, 2°1’3”S 58°10’26”W, rio Uatumã basin, 1 Oct 2011, L. Rapp Py-Daniel, R. Ota & D. Bastos. INPA 37417, 1, 234.2 mm SL, São Sebastião do Uatumã, igarapé 3, left margin of rio Jatapu, 2°00’7”S 58°11’35”W, rio Uatumã basin, 27 Sep 2011, L. Rapp Py-Daniel, R. Ota & D. Bastos. INPA 41833, 2, 155.3 – 165.1 mm SL, Tapauá, igarapé Jacinto, in front the camp, 5°43’18”S 63°14’4”W, rio Purus drainage, 15 Aug 2012, R. R. de Oliveira, L. Rapp Py-Daniel, A. Oliveira & A. Negrão da Silva. INPA 41933, 1, 117.4 mm SL, Tapauá, rio Ipixuna, boca do igarapé Jibóia, 5°42’12”S 63°17’37”W, rio Purus drainage, 19 Aug 2012, R. R. de Oliveira, L. Rapp Py-Daniel, A. Oliveira & A. Negrão da Silva. INPA 43879, 3, 165.0– 195.3 mm SL, Nhamundá, downstream lagoa Sete Ilhas, 1°50’28”S 57°4’20”W, Nov 2013, V. N. Machado, E. D. Ribeiro & R. A. Collins. INPA 48488, 3, 142.0– 224.4 mm SL, Tapauá, rio Ipixuna, floresta Tapauá, 6°33’33”S 63°31’19”W, rio Purus drainage, 8 Oct 2013, G. C. Barros & D. Mendes. INPA 48856, 1, 137.6 mm SL, Tapauá, rio Ipixuna, 6°21’17”S 63°14’22”W, rio Purus drainage, 9 Sept 2013, T. Couto & G. C. Barros. INPA 49185, 1, 195.2 mm SL, Japurá, Lago margem esquerda do rio Japurá, 1°39’6”S 69°12’24”W, 13 Sept 2014, R. Collins. MZUSP 34211, 2, 190.1 – 237.8 mm SL, Tefé, rio Tefé, lago Mucura, 3°20’29”S 64°44’43”W, 30 Aug 1979, M. Goulding. MZUSP 34767, 1, 288.7 mm SL, Novo Airão, rio Negro, arquipélago de Anavilhanas, 2°44’37”S 60°44’36”W, Jan 1981, M. Goulding. MZUSP 34768, 1, 203.8 mm SL, Novo Airão, rio Negro, arquipélago de Anavilhanas, 2°44’37”S 60°44’36”W, Nov 1980, M. Goulding. MZUSP 34769, 1, 208, 5 mm SL, Novo Airão, rio Negro, arquipélago de Anavilhanas, Margem das Ilhas, 2°44’37”S 60°44’36”W, Oct 1981, M. Goulding. MZUSP 34770, 36, 192.7 – 266.9 mm SL, Novo Airão, rio Negro, arquipélago de Anavilhanas, Igapó, 2°44’37”S 60°44’36”W, Jan 1981, M. Goulding. MZUSP 82143, 2, 241.8 – 255.6 mm SL, Santa Izabel do Rio Negro, rio Marauiá, marginal lake, rio Negro drainage, 0°12’00”S 64°51’58”W, 14 Oct 1979, M. Goulding. NUP 17001, 3, 170.5 – 222.5 mm SL, Novo Airão, rio Negro, 15 Jan 1981, M. Goulding. Pará State: INPA 1196, 2, 242.0– 251.5 mm SL, Oriximiná, lago Tapajem, rio Trombetas, 12 Apr 1985, L. Rapp Py-Daniel & E. G. Ferreira. INPA 1197, 2, 212.2 –216.0 mm SL, Oriximiná, downstream of cachoeira Porteira, 1°5’44”S 57°2’27”W, 3 Oct 1985, L. Rapp Py-Daniel & E. G. Ferreira. INPA 1198, 2, 175.7 – 176.3 mm SL, Oriximiná, downstream of cachoeira Porteira, 1°5’44”S 57°2’27”W, 13 Apr 1985, E. G. Ferreira & M. Jégu. INPA 1199, 2, 215.5 – 253.2 mm SL, Oriximiná, lago Tapagem, 11 Oct 1985, E. G. Ferreira & L. Rapp Py-Daniel. INPA 4360, 1, 261.5 mm SL, Oriximiná, lagoa Tapagem, 13 Apr 1985, E. G. Ferreira & M. Jégu. INPA 5413, 1, 62.1 mm SL, Oriximiná, rio Trombetas, pedral na margem, 6 Oct 1985, E. Ferreira. INPA 32274, 1, 97, 6 mm SL, Oriximiná, Porto Trombetas, rio Trombetas, 1°25’42”S 56°39’32”W, 30 Sep 2005, J. Zuanon. MZUSP 8268, 1, 94.4 mm SL, Oriximiná, rio Trombetas, 16–18 Dec 1967, Expedição Permanente à Amazônia. MZUSP 15822, 1, 235.2 mm SL, Oriximiná, beach upstream of the mouth of the lago Jacaré, reserva biológica do rio Trombetas, 1º20’00”S 56º51’00”W, 14 Jul 1979, R. M. C. Castro. MZUSP 22113, 1, 121.3 mm SL, Itaituba, ilha da Barreirinha, next to São Luiz, 4º28’5”S 56º15’50”W, 21 Nov 1970, EPA. MZUSP 23738, 1, 251.4 mm SL, Oriximiná, lago Jacaré, rio Trombetas, 7–11 Dec 1969, Expedição Permanente à Amazônia. MZUSP 34281, 1, 150.1 mm SL, Oriximiná, rio Trombetas, 20 km acima da boca do rio, 1º38’38”S 55º58’17”W, Oct 1983, M. Goulding. Roraima State: INPA 35679, 1, 201.9 mm SL, Caracaraí, rio Anaua, tributary of rio Branco, Acampamento próximo a ressaca do defunto, 1°7’42”S 60°23’38”W, rio Negro basin, 16 Apr 2007, E. Ferreira, J. Zuanon & L. Rapp Py-Daniel. INPA 36009, 1, 249.4 mm SL, Caracaraí, rio Viruá, camp Viruá, 0°20’23”S 61°9’40”W, 13 Apr 2007, J. Zuanon, E. Ferreira & L. Rapp Py-Daniel. MZUSP 23284, 3, 86.5–97.1 mm SL, Rorainópolis, rio Jauaperi, 100 km above mouth, 0°13’53”S 61°4’3”W, Nov 1998, T. Roberts.