Knodus guajajara Aguiar, Brito, Ottoni & Guimaraes 2022, new species
Creators: name: Aguiar, Rayane G.
name: Guimarães, Erick C.
name: Brito, Pâmella S. de
name: Santos, Jadson P.
name: Katz, Axel M.
name: Dias, Luiz Jorge B. da S.
name: Carvalho-Costa, Luis Fernando
name: Ottoni, Felipe P.
Publisher: name: Zenodo
Year: 2022
Subjects: Biodiversity
Taxonomy
Animalia
Chordata
Actinopterygii
Characiformes
Characidae
Knodus
Knodus guajajara

description: Knodus guajajara Aguiar, Brito, Ottoni & Guimarães, new speciesurn:lsid:zoobank.org:act: 4EEDDC6E-4088-4B60-828D-AF79EF84DC26
(Figs. 1–3; Tabs. 2–3)
Knodus victoriae [non Knodus victoriae (Steindachner, 1907)]. ―Guimarães et al. (2020a:90). ―Oliveira et al. (2020:6–7).
Holotype. CICCAA 4883, 31.4 mm SL, Alto Alegre do Pindaré municipality, Igarapé Arapapá, Pindaré River drainage, Mearim River basin, 03°42’26”S 46°00’25”W, Nov 2016. E. C. Guimarães & P. S. Brito.
Paratypes. All from Brazil, Maranhão State: CICCAA 1535, 1, 29.2 mm SL, collected with holotype. CICCAA 1585, 3, 28.0– 34.7 mm SL, Alto Alegre do Pindaré municipality, igarapé Arapapá, Pindaré River drainage, Mearim River basin, 03°42’26”S 46°00’25”W, Nov 2015, E. C. Guimarães & P. S. Brito. CICCAA 4860, 2 C&S, 29.9–31.6 mm SL, Alto Alegre do Pindaré municipality, igarapé Arapapá, Pindaré River drainage, Mearim River basin, 03°42’26”S 46°00’25”W, Nov 2015, E. C. Guimarães & P. S. Brito. LBP 31041, 16, 24.5–31.4 mm SL, Alto Alegre do Pindaré municipality, Igarapé Igarapá, Pindaré River drainage, Mearim River basin, 03°45’51”S 46°08’15”W, Nov 2015, E. C. Guimarães & P. S. Brito. CICCAA 4858, 5 C&S, 22.9–27.0 mm SL, Alto Alegre do Pindaré municipality, Igarapé Igarapá, Pindaré River drainage, Mearim River basin, 03°45’51”S 46° 08’15”W, Nov 2015, E. C. Guimarães & P. S. Brito. CICCAA 1517, 2, 21.8–24.4 mm SL, Alto Alegre do Pindaré municipality, igarapé Caititu, Pindaré River drainage, Mearim River basin, 03°42’30”S 46°01’19”W, Jul 2017, E. C. Guimarães & P. S. Brito. CICCAA 4859, 2 C&S, 23.5–27.6 mm SL, Alto Alegre do Pindaré municipality, igarapé Caititu, Pindaré River drainage, Mearim River basin, 03°42’30”S 46°01’19”W, Jul 2017, E. C. Guimarães & P. S. Brito. CICCAA 1536, 2, 28.8–29.8 mm SL, Buriticupu municipality, Buritizinho River, Pindaré River drainage, Mearim River basin, 04°11’53”S 46°28’41”W, Nov 2016, E. C. Guimarães & P. S. Brito. CICCAA 4861, 1 C&S, 31.9 mm SL, Buriticupu municipality, Buritizinho River, Pindaré River drainage, Mearim River basin, 04°11’53”S 46°28’41”W, Nov 2016, E. C. Guimarães & P. S. Brito. CICCAA 1227, 1, 29.6 mm SL, Buriticupu municipality, Buritizinho River, Pindaré River drainage, Mearim River basin, 04°19’45”S 46°29’46”W, 27 Jan 2017, E. C. Guimarães & P. S. Brito. UFRJ 7023, 10, 22.8–29.3 mm SL, Alto Alegre do Pindaré municipality, igarapé Jenipapo, Pindaré River drainage, Mearim River basin, 03°51’20”S 46°11’09”W, Jul 2017, E. C. Guimarães & P. S. Brito. CICCAA 4862, 5 C&S, 23.9–29.3 mm SL, Brazil, Maranhão State, Alto Alegre do Pindaré municipality, igarapé Jenipapo, Pindaré River drainage, Mearim River basin, 03°51’20”S 46°11’09”W, Jul 2017, E. C. Guimarães & P. S. Brito. CICCAA 1321, 39, 19.4–29.2 mm SL, Miranda do Norte municipality, Mearim River basin, 04°19’45”S 46°29’46”W, Nov 2016, E. C. Guimarães & P. S. Brito. CICCAA 4863, 11 C&S, 19.7–24.4 mm SL, Miranda do Norte municipality, Mearim River basin, 04°19’45”S 46°29’46”W, Nov 2016, E. C. Guimarães & P. S. Brito. CIUEMA 1021, 8, 21.2–26.9 mm SL, Alto Alegre do Pindaré municipality, Igarapé Timbira, Pindaré River drainage, Mearim River basin, 03°32’57”S 44°39’38”W, Nov 2015, E. C. Guimarães & P. S. Brito. CICCAA 3423, 42, 19.5–30.21 mm SL, CICCAA 3424, 57, 22.35–26.9 mm SL,, Chapadinha municipality, Riacho da Raiz, RESEX Chapada Limpa, Munim River basin, 03°53’45”S 43°29’21”W, 11 Aug 2019, J. Reis, L. Oliveira, F. Ottoni, R. Fernandes & A. Silva. Chapadinha municipality, Bandeira River, Povoado Mata do Jeroca, RESEX Chapada Limpa, Munim River basin, 03°59’40”S 43°29’24”W, 11 Aug 2019, J. Reis, L. Oliveira, F. Ottoni, R. Fernandes & A. Silva. CICCAA 3425, 22, 20.22–26.71 mm SL, CICCAA 3426, 6, 28.87–32.6 mm SL, Chapadinha municipality, stream at Bairro Aldeia, Munim River basin, 03°44’53”S 43°21’32”W, 28 Jan 2019, F. Carvalho, H. Silva, L. Oliveira & I. Gôuvea. CICCAA 3467, 2, 21.22–21.43 mm SL, Anapurus municipality, stream on the road at Povoado de Paços, Munim River basin, 03°33’44”S 43°03’52”W, Sep 2019, D. Campos, J. Reis & F. Ottoni. CICCAA 4808, 3, 25.19–34.2 mm SL, CICCAA 4822, 1, 36.89 mm SL, Chapadinha municipality, stream at balneário Repouso do Guerreiro, Bairro Independência, Munim River basin, 03°44’57”S 43°20’26”W, Nov 2019, B. Furtado, M. Paiva, A. Bezerra, M. Coelho & I. Gouvêa. CICCAA 4490, 5, 24.73–29.11 mm SL, Chapadinha municipality, Riacho Fundo, Munim River basin, 03°42’20”S 43°31’46”W, 23 Sep 2018, L. Sousa, L. Oliveira & I. Gouvêa, CICCAA 4491, 3 C&S 23.26–28.19 mm SL, Chapadinha municipality, Riacho Fundo, Munim River basin, 03°42’20”S 43°31’46”W, 23 Sep 2018, L. Sousa, L. Oliveira & I. Gôuvea.
Morphological diagnosis. Knodus guajajara differs from K. borki Zarske, 2008 and K. delta Géry, 1972 by having a complete lateral line (vs. incomplete lateral line) and from K. cupariensis de Sousa, Silva-Oliveira, Canto & Ribeiro, 2020 and K. geryi Lima, Britski & Machado, 2004 by having caudal fin lobes with sparse chromatophores and lacking basal blotches (vs. a dark basal blotch on each caudal fin lobe, Sousa et al., 2020; fig. 1); from Knodus borki, K. diaphanus (Cope, 1878), K. victoriae, K. heteresthes (Eigenmann, 1908), K. deuterodonoides (Eigenmann, 1914), K. longus Zarske & Géry, 2006, K. septentrionalis Géry, 1972, K. figueiredoi Esguícero & Castro, 2014, K. gery i, K. meridae Eigenmann, 1911, K. nuptialis Menezes & Marinho, 2019, K. orteguasae (Fowler, 1943), K. tiquiensis Ferreira & Lima, 2006, K. angustus Menezes, Ferreira & Netto-Ferreira, 2020, K. rufford Deprá, Ota, Vitorino-Júnior & Ferreira, 2021 and K. obolus Deprá, Ota, Vitorino-Júnior & Ferreira, 2021 by having 20–25 branched rays in the anal-fin (mode 23) (vs. 12–19, combined); and from K. tiquiensis by having a single humeral spot (vs. two). Knodus guajajara is distinguished from K. breviceps (Eigenmann, 1908) and K. savannensis Géry, 1961 by having a conspicuous round humeral blotch (vs. inconspicuous and vertically elongate); from K. dorsomaculatus Ferreira & Netto-Ferreira, 2010 by having a hyaline dorsal-fin (vs. dark blotch on the base of the first five branched dorsal fin rays); from K. alpha (Eigenmann, 1914), K. chapadae (Fowler, 1906), K. geryi, K. hypopterus (Fowler, 1943), K. mizquae (Fowler, 1943) and K. shinahota Ferreira & Carvajal, 2007 by having 4 or 5 rows of scales between the lateral line and the dorsal-fin origin (vs. 6 rows of scales); from K. cinarucoensis (Román-Valencia et al., 2008), K. gamma Géry, 1972 and K. longus Zarske & Géry, 2006 by having 12 or 13 scales in the median series between the tip of the supraoccipital spine and the dorsal-fin origin (vs. 10 or 11 rows of scales in K. gamma and 17 to 18 in K. longus); from K. jacunda (Fowler, 1913), K. moenkhausii (Eigenmann & Kennedy, 1903), Knodus cismontanus (Eigenmann, 1914), Knodus caquetae Fowler, 1945, K. tanaothoros (Weitzman, Menezes, Evers & Burns, 2005), K. weitzmani (Menezes, Netto-Ferreira & Ferreira, 2009) and by having 3 to 5 maxillary teeth (vs. absence in K. jacunda, one in K. caquetae, and 2 in K. moenkhausii, K. tanaothoros, K. weitzmani and K. cismontanus); from K. megalops Myers, 1929 by having 3 or 4 tricuspid teeth in the premaxillary outer row (vs. 5); from K. jacunda by having 3 to 5 maxillary teeth (vs. absence); from K. smithi (Fowler, 1913) by having 3 to 5 cusps on the teeth of the inner row of the premaxilla (vs. 7); and from K. figueredoi, K. heteresthes, K. meridae, K. mizquae, K. moenkhausii, K. victoriae, K. pasco Zarske, 2007 by having 12 circumpeduncular scales (vs. 13–14 combined). Furthermore, Knodus guajajara differs from K. victoriae by having more total vertebrae 33–35, mode 34 (vs. 30–33, mode 32).
Description. Morphometric data presented in Tabs. 2–3. Body comparatively small, with largest specimen examined measuring 37.7 mm SL. Greatest body depth at dorsal-fin origin. Dorsal profile of head convex from upper lip to vertical through middle portion of eye; slightly concave from this point to tip of supraoccipital spine; straight to slightly convex from posterior tip of supraoccipital spine to dorsal-fin origin; dorsal-fin base straight; slightly convex to straight from end of dorsal-fin base to adipose fin and concave from latter point to anterior dorsal-procurrent ray. Ventral profile of body convex from lower lip to anal-fin origin; straight, posterodorsally inclined along anal-fin base. Dorsal and ventral profile of caudal peduncle slightly concave.
Mouth sub-terminal; jaws isognathous. Posterior terminus of maxilla extending beyond anterior margin of orbit. Premaxillary teeth in two rows; outer row with 3(18) and 4(8) tricuspid teeth, inner row with 4(26) tri-to pentacuspid teeth. Maxilla with 3(11), 4(13), 5(2) tri-to pentacuspid teeth. Dentary with three anteriormost teeth large, tri and pentacuspid teeth, followed by 4(2), 5(2), 6(4), 7(13) and 8(5) smaller, uni, tricuspid or pentacuspid teeth (Fig. 3).
Scales cycloid, moderately large, with 6–8 well-marked radii; circuli only present proximally. Lateral line complete, slightly curved ventrally along its anterior third, with 36(8), 37(61), 38*(137), 39(13), or 40(7) perforated scales. Longitudinal series of scales between dorsal-fin origin and lateral line 4(30) or 5*(202). Longitudinal series of scales between lateral line and pelvic-fin origin 4*(63), or 5(184). Predorsal scales 11(3), 12(106) or 13*(122). Circumpeduncular scales 12*(220). Single series of scales on anal-fin base.
Dorsal fin rays ii,7(45) or 8*(191). Dorsal-fin origin slightly posterior to middle of body, and slightly posterior to vertical through pelvic-fin origin. First unbranched ray approximately half length of second unbranched ray. Pectoral-fin rays i,9(9), 10(142) or 11*(94); tip of pectoral fin reaching or exceeds pelvic fin origin when adpressed. Pelvic-fin rays i,5,i(41) or i,6,i*(189); tip of pelvic fin usually reaching first anal fin rays when adpressed. Anal-fin rays iv, 20(2), 21(8), 22(40), 23*(140), 24(37) or 25(15). Anal-fin origin located at vertical through middle of dorsal fin. Anal-fin rays decreasing gradually in length. Caudal fin forked, lobes equal in size. Principal caudal-fin rays i,9,8,i(219). Dorsal procurrent caudal-fin rays 8(1), 9(1), 10(18), 11(3) or 12(3) and ventral procurrent caudal-fin rays 9(3), 10(2), 11(15), 12(3) or 13(3). Adipose-fin origin approximately at vertical through base of 19th to 21st branched anal-fin rays. Gill rakers on first gill arch 15(2), 16(4) or 17(2): hypobranchial 2(4) or 3 (4), ceratobranchial 7(8), cartilage between epibranchial and ceratobranchial 1(8), epibranchial 5(4) or 6(4). Gill rakers setiform. Branchiostegal rays 4(8), 3(8) on anterior ceratohyal and 1(8) on posterior ceratohyal. Total vertebrae 33(3), 34(18) or 35(8). First dorsal fin pterygiophore inserted between 10th and 12th vertebrae. First anal fin pterygiophore inserted between 16th and 17th vertebrae. Supraneurals 4(2), 5(12) or 6(9).
Color in alcohol. Ground of body and head light brown, with dorsal region of body (especially dorsal profile), dorsal portion of head (just above eyes), and upper snout area (upper jaw and adjacent areas) darker. Ventral region of trunk and head with light brown coloration, especially on scales adjacent to anal-fin base. Dark colored chromatophores concentrated on scales of dorsal region (from both body and head), on opercle, and lateral band of flank (especially on posterior region, near caudal peduncle and caudal-fin base). Conspicuous vertically elongated humeral spot, with some dark scattered chromatophores above and below this blotch. Lateral band formed by chromatophores located above lateral line, extending gradually from humeral blotch to middle rays of caudal fin, where they become thicker and more concentrated. All fins including adipose hyaline, with chromatophores on inter-radial membranes of dorsal fin. Anal and caudal fins with posterior margins dark grey.
Color in life. Yellowish coloration in dorsolateral region and silver coloration in ventrolateral region of body (Fig. 2). Gray lateral band located in middle portion of trunk, with bright pigment extending from operculum to caudal-fin base. Dorsal portion of eye yellowish-orange and lower portion silver; mouth and dorsolateral portion of head yellowish with concentrated chromatophores; operculum with silver coloration. Fins hyaline with chromatophores present and especially concentrated in medial region of dorsal fin, distal region of anal and caudal fins, on first pectoral-fin ray, and just posterior to medial lateral band on caudal fin. Adipose fin with yellowish-orange pigmentation; yellowish-orange pigments also present in middle region of caudal fin.
Sexual dimorphism. Hooks present on pelvic fins and anal fin of sexually mature males. Pelvic fins with 5 to 14 hooks per branched ray; anal fin with 2 to 8 hooks per ray. Hooks concentrated on anterior anal fin rays (Fig. 4).
Geographical distribution. Knodus guajajara occurs in the rivers, streams, and lagoons of the Mearim and Munim river basins, in the State of Maranhão, Northeast Brazil (Fig. 5).
Etymology. The specific epithet honors the Guajajara indigenous tribe, which is one of the most numerous indigenous peoples in Brazil. They inhabit more than 10 Indigenous Lands on the eastern margin of the Amazon, all located in Maranhão. A noun in apposition the language spoken by them is the Teneteara, from the Tupi-Guarani linguistic family.
Conservation status. Knodus guajajara occurs in two distinct river basins of Maranhão, the Mearim and Munim river basins. It was found in several collecting sites along these basins, and it is always abundant. Therefore, according to the guidelines given in the International Union for Conservation of Nature (IUCN) categories and criteria (IUCN, 2019), we recommend that Knodus guajajara should be categorized as Least Concern (LC).
Molecular species delimitation
Molecular diagnosis. Knodus guajajara is diagnosed molecularly by a combination of 19 nucleotide substitutions, four of them unique* (listed below):
COI 279 (C→A), COI 282 (C→T), COI 306 (C→T), COI 327 (C→T), COI 357 (A→G*), COI 372 (A→G*), COI 378 (A→G), COI 414 (T→C), COI 450 (T→C), COI 459 (C→T), COI 510 (T→C), COI 528 (C→T), COI 537 (C→T), COI 565 (C→T), COI 585 (T→C), COI 589 (C→T), COI 597 (C→T), COI 627 (A→G*), COI 645 (T→A*).
Traditional DNA Barcoding. COI sequences support the existence of a new species of Knodus inhabiting the Mearim and Munim River basins. After trimming, the final alignment yielded 401 base pairs with 132 variable sites and 62 haplotypes. Knodus guajajara is 14% divergent, on average, from the other taxa, with a minimum genetic distance of 11% to K. borki, K. caquetae and Knodus sp. “Maracaçumé”, and a maximum genetic distance of 16% to Bryconamericus exodon Eigenmann,1907 and Knodus tiquiensis. The genetic distance between the new species and K. victoriae is 13% (Tab. 4).
Phylogenetic analysis. The BI phylogenetic analysis delimited 19 lineages: two of them are outgroups (Bryconamericus species) and the remaining correspond to Knodus species (Fig. 6). One of the 17 lineages of Knodus represents the new species described herein (Knodus guajajara) with haplotypes from the Mearim and Munim river basins forming an exclusive clade supported by the highest possible support value (PP = 1) (Fig. 6). The BI phylogenetic analysis also delimited new lineages of Knodus inhabiting the Tocantins River (Knodus sp. “Marabá”) and the Maracaçumé River (Knodus sp. “Maracaçumé”). In addition, two well supported clades were recovered within Knodus cf. savannensis: the first one containing Knodus cf. savannensis (Tocantins River, Carolina, MA), Knodus “Guamá” and Knodus cf. savannensis (KT248218 and KT248219) (posterior probability = 0.96). The second clade of Knodus cf. savannensis corresponds to six haplotypes (KT248199, KT248200, KT248201, KT248202, KT248203, and KT248204) of Knodus cf. savannensis (PP = 1). Two other lineages closely related to K. victoriae were detected: Knodus cf. victoriae (Balsas River drainage) and Knodus cf. victoriae (Itapecuru River basin) (PP = 1).
GMYC, bPTP and ABGD. The results of the three species delimitation methods (GMYC, bPTP, and ABGD) were congruent (Fig. 6), and all three delimited the same 19 lineages. Two of them are outgroups (Bryconamericus species), and 17 are Knodus lineages (species) (Fig. 6). The new species herein described (K. guajajara) was recovered in all three species delimitation methods. Furthermore, some potential undescribed species were detected: Knodus “Marabá”, Knodus “Maracaçumé”, Knodus cf. victoriae (Itapecuru River basin) and Knodus cf. victoriae (Balsas River drainage). Knodus victoriae (upper Parnaiba River basin) was also recovered, as well as two K. cf. savannensis clades.
description: Published as part of Aguiar, Rayane G., Guimarães, Erick C., Brito, Pâmella S. de, Santos, Jadson P., Katz, Axel M., Dias, Luiz Jorge B. da S., Carvalho-Costa, Luis Fernando & Ottoni, Felipe P., 2022, A new species of Knodus (Characiformes: Characidae), with deep genetic divergence, from the Mearim and Munim river basins, Northeastern Brazil, and evidence for hidden diversity in adjacent river basins, pp. 1-27 in Neotropical Ichthyology (e 210173) (e 210173) 20 (2) on pages 7-19, DOI: 10.1590/1982-0224-2021-0173, http://zenodo.org/record/13350457