A new species of Hypostomus Lacepède, 1803 (Siluriformes: Loricariidae) from the Mearim River basin, northeastern Brazil Author Oliveira, Rafael Ferreira De Universidade Federal do Maranhão, Laboratório de Sistemática e Ecologia de Organismos Aquáticos, Campus de Chapadinha, BR- 222, KM 04, S / N, Boa Vista, 65500 - 000, Chapadinha, MA, Brazil. & Universidade Federal do Maranhão, Programa de Pós-Graduação em Biodiversidade e Conservação, Av. dos Portugueses 1966, Cidade Universitária Dom Delgado, CEP 65080 - 805, São Luís, MA, Brazil. Author Guimarães, Erick Cristofore 0000-0003-4480-5452 Universidade Federal do Oeste do Pará, Programa de Pós-graduação Sociedade Natureza e Desenvolvimento, Instituto de Ciências da Educação, 68040 - 070, Santarém, PA, Brazil. erick. ictio @ yahoo. com. br; https: // orcid. org / 0000 - 0003 - 4480 - 5452 Universidade Federal do Maranhão, Departamento de Biologia, Laboratório de Zoologia de Invertebrados, Av. dos Portugueses 1966, Cidade Universitária Dom Delgado, 65080 - 805, São Luís, MA, Brazil. erick.ictio@yahoo.com.br Author Brito, Pâmella Silva De Universidade Federal do Maranhão, Centro de Ciências de Chapadinha, Campus Chapadinha, Programa de Pós-Graduação em Ciências Ambientais, BR- 222, KM 04, Boa Vista, 65500 - 000, Chapadinha, MA, Brazil. Author Ottoni, Felipe Polivanov Universidade Federal do Maranhão, Laboratório de Sistemática e Ecologia de Organismos Aquáticos, Campus de Chapadinha, BR- 222, KM 04, S / N, Boa Vista, 65500 - 000, Chapadinha, MA, Brazil. & Universidade Federal do Maranhão, Programa de Pós-Graduação em Biodiversidade e Conservação, Av. dos Portugueses 1966, Cidade Universitária Dom Delgado, CEP 65080 - 805, São Luís, MA, Brazil. & Universidade Federal do Maranhão, Centro de Ciências de Chapadinha, Campus Chapadinha, Programa de Pós-Graduação em Ciências Ambientais, BR- 222, KM 04, Boa Vista, 65500 - 000, Chapadinha, MA, Brazil. text Zootaxa 2022 2022-12-12 5219 4 339 352 journal article 207005 10.11646/zootaxa.5219.4.2 dff026a6-6655-465f-9b25-8337b098d2b8 1175-5326 7426696 D918AA38-2D46-4B55-92EF-2564D350B8F7 Hypostomus krikati , new species Figure 1 , Table 1 . Hypostomus cf. plecostomus : Soares (2005) : 1 –131 (inventory of species) Hypostomus cf. plecostomus : Guimarães et al . (2020a) :e20201023 (inventory of species). Hypostomus aff. plecostomus : Guimarães et al . (2020b) :32 –51 (inventory of species) Hypostomus aff. plecostomus : Guimarães et al . (2021) :1 –54 (inventory of species). Holotype . CICCAA 01731, 209.3 mm SL, Brazil , Maranhão state , Rio Pindaré ( Mearim River basin), Bom Jesus das Selvas municipality, Pindaré River , Mearim River basin, 4°23′52.0″S 46°50′33.5″W , 26.Jul. 2014 , Guimarães E.C. and Brito P.S. Paratypes . All from Brazil , Maranhão state : CICCAA 06160, 1, 120.1 mm SL.; CICCAA 06161, 1, 177.6 mm SL.; CICCAA 06162, 1, 134.3 mm SL.; collected with holotype.—CICCAA 00459, 1, 116.3 mm SL, Rio Zutiua ( Mearim River basin), Santa Inês municipality, 3°43′1.79″S , 45°32′2.98″W ; Guimarães E.C. and Brito P.S. ; 19 Jan 2014 .; 19 Jan 2014 .; CICCAA 00462, 3, 103.3– 129.7 mm SL; CICCAA 07109, 1, 99.1 mm SL Rio Zutiua ( Mearim River basin), Santa Inês municipality, 3°43′1.79″S , 45°32′2.98″W ; Guimarães E.C. and Brito P.S. ; 19 Jan 2014 .; 10 Oct 2013 .; CICCAA 00461, 1, 142.9 mm SL, Igarapé Mineirão ( Mearim River basin), Alto Alegre do Pindaré municipality, 3°42′30.23″S , 45°56′20.33″W ; Guimarães E.C. and Brito P.S. ; 18 Jan 2014 .; CICCAA 00467, 1, 107.9 mm SL, Lago do Lírio ( Mearim River basin), Alto Alegre do Pindaré municipality, 3°39′12.22″S , 45°46′25.06″W ; Guimarães E.C. and Brito P.S. ; 18 Jan 2014 .; CICCAA 00468, 1, 126.2 mm SL, Igarapé Igarapá ( Mearim River basin), Bom Jardim municipality, 3°45′51.31″S , 46° 8′15.45″W ; Guimarães E.C. and Brito P.S. ; 15 Jan 2014 .; CICCAA 00525, 1, 122.8 mm SL.; CICCAA 00526, 2, 110.7–119.0 mm SL, Rio Zutiua ( Mearim River basin), Santa Inês municipality, 3°43′1.79″S , 45°32′2.98″W ; Guimarães E.C. and Brito P.S. ; 10 Out 2013.; CICCAA 00529, 1, 123.0 mm SL, Igarapé do Fausto ( Mearim River basin), Alto Alegre do Pindaré municipality, 3°42′50.26″S , 46° 3′29.61″W ; Guimarães E.C. and Brito P.S. ; Dez 2015 .; CICCAA 06159, 1, 204.1 mm SL, Igarapé Jenipapo ( Mearim River basin), Alto Alegre do Pindaré municipality, 3°51′20.24″S , 46°11′9.56″W ; Guimarães E.C. and Brito P.S. ; Out 2013.; CIUEMA 1300, 1, 191.9 mm SL, Igarapé Jenipapo ( Mearim River basin), Alto Alegre do Pindaré municipality, 3°51′20.24″S , 46°11′9.56″W ; Guimarães E.C. and Brito P.S. ; Out 2013.; CIUEMA 1301, 1, 130.1 mm SL, Igarapé Timbira ( Mearim River basin), Alto Alegre do Pindaré municipality, 3°41′43.77″S , 45°55′13.80″W ; Guimarães E.C. and Brito P.S. ; 14 Jan 2014 .; UFRJ 11170, 2, 98.9–113.6 mm SL, Rio Zutiua ( Mearim River basin), Santa Inês municipality, 3°43′1.79″S , 45°32′2.98″W ; Guimarães E.C. and Brito P.S. ; 19 Jan 2014 . Diagnosis. Hypostomus krikati sp. n. shares with members of the H. plecostomus super-group sensu Jardim de Queiroz (2020) the following characters states: mandible small to intermediate sized, low number of teeth (6–41 combined), teeth with a short crown, completely plated abdominal area, and body and fins with dark blotches or spots. The new species is distinguished from the members of H. cochliodon super-group sensu Armbruster (2003) , by having slender villiform bicuspid teeth (vs. robust spoon-shaped teeth—see Armbruster (2003) fig. 1a vs. b and c); from the members of H . auroguttatus super-group sensu Jardim de Queiroz (2020) , by having shorter mandible, low number of teeth (18–30), dark blotches over the body and fins, and the abdominal area plated (vs. large size of the mandible, high number of teeth (usually more than 30), pale blotches over the body and fins, and abdominal area often naked or partially naked—see Jardim de Queiroz (2020)) ; from the members of H. hemiurus super-group sensu Jardim de Queiroz 2020 ( H. crassicauda Boeseman, 1968 , H. hemiurus (Eigenmann, 1912) , H. micromaculatus Boeseman, 1968 , and H. saramaccensis Boeseman, 1968 ) by having roundish dark spots on the body (vs. slightly transverse dark spots in H. crassicauda , H. hemiurus , and H. micromaculatus —see Weber et al . (2012) , figs. 8d and 9a,c) and abdomen completely covered by plates (vs. naked abdomen or with few disperse plates in H. saramaccensis —see Boeseman (1968)) ; from Hypostomus nematopterus by having dorsal-fin spine not extremely elongated, reaching approximately in a vertical line through the anal-fin base (vs. extremely elongated dorsal-fin spine, reaching or extending beyond the caudal-fin base—see Weber et al . (2012) , fig. 9d); and from H. velhochico by having body with non-aligned spots (vs. body with horizontally aligned spots—see Zawadzki et al. (2017) , figs 1 and 3). Furthermore, the new species differs from the members of Hypostomus plecostomus supergroup except Hypostomus affinis (Steindachner, 1877) , H . ancistroides (Ihering 1911) , H . argu s ( Fowler, 1943 ), H . borellii ( Boulenger, 1897 ) , H. boulengeri (Eigenmann & Kennedy 1903) , H . careopinnatus Martins, Marinho, Langeani & Serra, 2012 , H. carinatus (Steindachner 1881) , H. commersoni Valenciennes 1836 , H. corantijni Boeseman 1968 , H. delimai Zawadzki, Oliveira & Debona 2013 , H. formosae Cardoso, Brancolini, Paracampo, Lizzaralde, Covain & Montoya-Burgos 2016 , H . holostictus ( Regan, 1913 ) , H. hoplonites Rapp Py-Daniel 1988 , H. interruptus ( Miranda Ribeiro 1918), H. niceforoi ( Fowler 1943 ) , H. nigrolineatus Zawadzki, Carvalho, Birindelli & Azevedo 2016 , H . pantherinus Kner 1854 , H. paucimaculatus Boeseman 1968 , H. plecostomus (Linnaeus 1758) , H . piratatu Weber, 1986 , H. pusarum ( Starks 1913 ) , H. rhantos Armbruster, Tansey & Lujan 2007 , H. spiniger (Hensel 1870) , H . subcarinatus Castelnau, 1855 , H . tapijara Oyakawa, Akama & Zanata, 2005 , and H. watwata Hancock 1828 by having strongly-developed odontodes along lateral keels (vs. lacking or moderately developed odontodes); from Hypostomus carinatus , H . delimai , H. hoplonites , H. spiniger , H. pusarum , and H. watwata by the number of plates in contact with the posterior border of the supraoccipital bone (only one shield-shaped fused predorsal plate in H. krikati sp. n. vs. 3–10 plates, combined); from H . affinis , H . ancistroides , H. argus , H . borellii , H . commersoni , H . interruptus , H . subcarinatus and H . tapijara by having 25 to 26 plates at the median lateral series (vs. 27–32, combined); from H . rhantos by having medium spots on body (vs. extremely small spots); from H . nigrolineatus by having a well-developed medial buccal papilla (vs. having a rudimentary papilla); from H . pusarum by having a buccal papilla pointed and smooth (vs. buccal papilla globose and rough); from H . corantijni , H . gymnorhynchus , and H . paucimaculatus by having body with non-aligned and round spots (vs. ellipsoid spots in H . corantijni , H . gymnorhynchus and H . paucimaculatus ); from H . pantherinus for having rudimentary crests on the supraoccipital and pterotic-supracleithrum (vs. sharp crests on supraoccipital and pterotic-supracleithrum); from H . careopinnatus by the presence of an adipose-fin (vs. absence); from H . famosae by having pectoral-fin spine with well-developed odontodes (vs. pectoral-fin spine slightly covered with weakly developed odontodes); from H . boulengeri by having well-developed keels reaching a vertical line trough adipose-fin origin (vs. well-developed keels reaching the caudal-fin base); from H . famosae and H . boulengeri by having 13–15 (mode 14) plates between anal and caudal-fin (vs. 11–14, mode 12 in H . formosae , 13–15, mode 13 in H . boulengeri ), and 5–7 (mode 6) plates between adipose and caudal-fin (vs. 4–6, mode 5 in H . formosae and H . boulengeri ). Furthermore, the new species here described differs from H . niceforoi by having a maximum of 30 teeth in the dentary (vs. more than 60); from H . piratatu by having teeth with short crowns (vs. elongated crowns); from H . holostictus by having dorsal-fin spine short, when depressed, reaching approximately in a vertical line through the anal-fin base (vs. dorsal-fin spine elongated, reaching or extending beyond the adipose-fin base); and from H. plecostomus by lacking an exposed pterygiophore, possessing preanal region naked, covered by skin or by the extension of the plates of the ventral series of some adults (vs. presence of an exposed pterygiophore anterior to anal-fin). Description. Counts and measurements listed in Table 1 . Body long with rough plates. Dorsal profile rising convexly at angle of approximately 30º from snout tip to posterior end of supraoccipital process, then at angle around 8º up to dorsal-fin origin, and decreasing gently from that point to end of caudal peduncle, with slightly concave area at last dorsal-fin ray level. Head broad and depressed, dorsally covered with dermal ossifications. Tip of snout naked or covered by plates; some specimens exhibiting intermediate stages, varying in all sizes classes ( Fig. 2 ). Anterior profile of snout rounded in dorsal view. Median longitudinal bulge associated with mesethmoid usually conspicuous from snout tip to transverse line between nares. Eye small (11.2–14.9 % of HL), dorsolaterally placed. Interorbital space straight or slightly convex in frontal view. Pair of weak ridges on dorsal surface of head, each one beginning lateral to naris, passing through upper margin of orbit and finishing on central portion of pterotic-supracleithrum. Supraoccipital bone with well-developed median crest; posterior portion of supraoccipital bone bordered by first predorsal plate. First predorsal plate fused (single plate), shield-like ( Fig. 3a ). TABLE 1 . Meristic and morphometric data of Hypostomus krikati sp. n. SD = Standard deviation. N=21.

Standard length (mm)	Holotype	Range	Mean	SD
209.3	98.9–209.3	133.8	–
Percentage of standard length
Head length	30.8	30.8–36.5	34.5	1.5
Predorsal length	37.0	37.0–44.7	40.9	2.0
Interdorsal length	16.9	12.9–18.1	15.0	1.4
Preanal length	62.8	62.7–69.9	64.7	2.2
Thoracic length	21.7	20.6–25.8	22.3	1.3
Abdominal length	21.7	20.9–25.0	22.3	1.1
Caudal peduncle length	32.1	30.0–35.9	33.3	1.8
Caudal peduncle depth	11.1	10.8–12.6	11.4	0.5
First dorsal-fin ray length	22.5	22.5–32.4	27.7	3.0
Dorsal-fin base length	27.3	23.1–28.5	26.2	1.4
Anal-fin spine length	10.8	10.7–13.8	12.4	0.9
First pectoral-fin ray length	28.3	28.1–38.6	32.2	2.4
First pelvic-fin ray length	22.2	22.2–29.0	26.2	1.7
Upper caudal-fin ray length	24.7	23.5–41.8	27.2	5.7
Lower caudal-fin ray length	27.6	25.5–52.4	33.3	6.1
Adipose-fin spine length	8.9	6.3–9.8	8.2	0.8
Body depth at dorsal-fin base	20.8	20.8–27.7	23.6	1.6
Cleithral width	29.0	28.2–34.1	30.0	1.4
Percentage of head length
Head depth	64.9	60.7–69.8	64.3	2.4
Snout length	61.8	59.2–65.7	61.9	1.7
Orbital diameter	11.6	11.2–14.9	13.4	1.1
Interorbital width	41.5	40.6–45.8	43.5	1.6
Mouth width	50.1	38.1–51.5	45.5	3.3
Dentary ramus length	16.3	11.4–16.6	13.7	1.5
Premaxillary ramus length	15.1	10.8–22.2	13.1	2.4
Maxillary barbel length	12.9	9.0–16.2	12.3	1.7
Counts	Holotype	Range	Mode
Median plates series	25	25–26	26
Predorsal plates	3	3–3	3
Plates bordering supraoccipital	1	1–1	1
Dorsal plates below dorsal-fin base	9	8–9	8
Plates between dorsal and adipose-fin	6	6–6	6
Plates between adipose and caudal-fin	6	5–7	6
Plates between end of anal-fin base and caudal-fin	14	13–15	14
Premaxillary teeth	25	15–27	23
Dentary teeth	24	18–30	26

FIGURE 1. Hypostomus krikati sp. n. Holotype, CICCAA 01731, 209.3 mm SL; Brazil, State of Maranhão, Municipality of Bom Jesus das Selvas, Pindaré River drainage, Mearim River basin, northeastern Brazil. FIGURE 2. Intraspecific variation in snout tip of Hypostomus krikati sp. n. A . 01731, 209.3 mm SL, plated tip. B . CICCAA 06159, 204.1 mm SL, naked tip. C . CIUEMA 1300, 191.9 mm SL, partially naked tip. FIGURE 3. Predorsal squamation pattern. A . Hypostomus krikati sp. n. (CICCAA 07109) 99.1 mm SL. B . Hypostomus pusarum (CICCAA 07108) 81. 5 mm SL. Red = predosal plate. Green = acessory predorsal plates. Yellow = supraoccipital plate. Blue = pterotic-supracleithrum. Mouth large. Premaxilla with 15–27 and dentary with 18–30 villiform bicuspid teeth. Teeth medium sized, robust, bicuspid, and curved inward distally; inner cusp with short crown. Tooth crown rounded, possessing externally smaller lateral cusp with approximately similar size to main cusp. Dentary ramus flat, approximately straight. Dentaries meet at obtuse angle (~95° to 112°). Median buccal papilla well developed with anterior portion approximately pointed. Lips well developed. Lower lip reaching or almost reaching horizontal line between gill openings; inner surface covered with numerous small papillae. Maxillary barbel short with free tip. Body covered by five lateral series of plates. Dorsal, mid-dorsal, median and mid-ventral plates series with well-developed keels. Dorsal and mid-dorsal plate series with well-developed keels from first series plate to vertical line through adipose-fin origin; median and mid-ventral plate series with well-developed keels only between the fifth and eighth first series plates. Median series bearing complete lateral line; lateral line with 25 to 26 plates. Midventral series strongly bent to fourth or fifth first plates. Ventral series slightly bent to form flat ventral surface of peduncle region. Preanal region naked, lacking exposed pterygiophore, covered by skin or eventually covered by extension of plates of ventral series in some adults.Abdomen covered with minute platelets in adults, with exception of very small areas around pectoral and pelvic-fin insertions, and at urogenital opening. Dorsal fin II,7; its origin just before vertical line through pelvic-fin insertion; dorsal-fin distal border slightly convex. Pectoral fin I,6, its distal border convex. Pectoral-fin spine slightly curved inward, covered with moderately developed odontodes, more developed on its distal portion, particularly in larger specimens.Tip of adpressed pectoral fin reaching to basal one-third to one-fourth of adpressed pelvic-fin spine. Tip of pectoral-fin spine rounded and with odontodes almost perpendicular to spine ( Fig. 5b ). Pelvic fin i,5, its distal border straight to slightly convex; its adpressed unbranched ray surpassing anal-fin origin. Adipose fin well-developed and inserted five to six plates after dorsal fin posterior insertion, with membrane extending over three plates of dorsal series. Anal fin i,4, its tip reaching the fifth to sixth plate after its origin. Rays of anal fin progressively increasing in length posteriorly, third branched ray usually longest. Caudal fin i,14,i, its margin falcate, with ventral lobe longer than dorsal. Color in alcohol. Ground color of head and trunk dark reddish-brown, with approximately round dark brown spots, except on ventral and ventral-lateral regions of caudal peduncle, ventral region of head, cleithrum, pectoral and pelvic-fin spines ventral region, and anal region. Dorsal and dorsolateral region of body and head with spots more conspicuous and well developed than abdomen. Spots more numerous especially on head dorsal and dorsolateral region. Spotting pattern with little variation between size classes. Dark spots usually larger and with larger interspaces between spots in species below 120 mm SL. Spots progressively more numerous on head, trunk and fins in specimens above 180 mm SL. Dorsal and pectoral fins with dark spots, pectoral fin spots only on dorsal region, mainly on proximal region and along spines and first branched rays. Spots of dorsal fin arranged in vertical rows; one vertical row per interradial space, except for two specimens possessing one additional inconspicuous anterior row per interradial space. Pelvic fin with dark spots usually grouped on median region of branched rays. Anal fin usually lacking spots, rarely with inconspicuous spots. Caudal fin with few spots; caudal-fin spots occasionally vertically aligned in two to three bands. Head dark spots smaller than eye pupil; anterior spots smaller and progressively increase in size from anterior to posterior direction. Body and fins spots lager than head spots, progressively increase in size from anterior to posterior direction; larger body and fins spots approximately similar in size to eye pupil. Body spots not aligned. Abdomen spots rounded not aligned, very light and sometimes inconspicuous, slightly larger than body spots and pupil. Sexual dimorphism. No apparent sexual dimorphism. Distribution . The new species is known from eight localities in the Mearim River basin, northeast Brazil ( Fig. 4 ). This river basin is located in a transition zone between the Amazon rainforest and the Brazilian Cerrado ( Ab’Sáber, 2003 ; Fiaschi & Pirani, 2009 ). Ecological notes. Specimens of H. krikati sp. n. were collected in different locations of the Pindaré River drainage. The region is part of the Gurupi Mosaic, where the floristic complex of the Amazon Biome and of transitional areas with the Brazilian Cerrado is formed ( Castro & Martins 1999 ; Celentano et al . 2018 ). Currently, this region is one of the most deforested areas of the Amazon Biome in Brazil , often affected by human actions, causing serious problems for the region, such as loss of forest cover and silting of rivers ( Celentano et al . 2018 ). Etymology. The specific epithet krikati , honors the Krikati native people, a Jê-speaking culture, occurring in the Gurupi Mosaic region.