Salminus santosi, Lima, 2022

Lima, Flávio C. T., 2022, Revision of the smaller-sized dorados (Salminus), with comments on the monophyly of the genus and its biogeography (Characiformes: Bryconidae), Zootaxa 5226 (1), pp. 1-66 : 44-50

Salminus santosi , new species

( Figs. 15–16 )

Salminus hilarii (not Valenciennes): Valenciennes, in Cuvier & Valenciennes, 1850: 65 (in part; “rivières de l’intérieur du Brésil ”); Castelnau, 1855: 60–61, pl. 31, fig. 1 (“le rio Vermelho, qui traverse la ville de Goyaz”); Santos et al., 1984: 41 (photo; Brazil, Pará, lower rio Tocantins); Begossi & Garavello, 1990: 348 (rio Tocantins basin, Brazil; common names); Ribeiro et al., 1995: 330 (upper rio Tocantins basin, Brazil; common name); Lucinda et al., 2007: 77 (middle rio Tocantins basin, Tocantins, Brazil; occurrence); Garavello et al., 2010: 577, 580 (middle rio Tocantins basin, Maranh ã o state, Brazil; importance to fisheries); Venere & Garutti, 2011: 111 (photo; tributaries of rio Araguaia, Barra do Garças, Mato Grosso, Brazil; common names, ecological notes, maximum size); Bartolette et al., 2012: 62 (rio Tocantizinho, region of Serra da Mesa dam, Goiás, Brazil); Albrecht et al., 2012: 206 (rio Tocantizinho, region of Serra da Mesa dam, Goiás, Brazil; diet); Bartolette et al., 2017: 10 (rio Tocantins, Lageado dam, Tocantins, Brazil; occurrence); Dagosta & de Pinna, 2019: 89 (in part: “Upper Tocantins, Araguaia, lower Tocantins ”).

Salminus cf. hilarii: Aloísio et al., 2005: 13 ( rio Novo , tributary of rio Tocantins, Tocantins, Brazil; occurrence).

Salminus sp. : Abe et al., 2014: 4, 8–12 (rio Tapirapé, Pará, Brazil; phylogenetic relationships, biogeography).

Salminus iquitensis (not Nakashima): Lima, 2017: 189 (listed, comparative material, lots MZUSP 26925 and MZUSP 53620).

Diagnosis. Salminus santosi can be diagnosed from all congeners, except S. iquitensis , by the presence of numerous, tiny stripes concentrated at the interradial membranes of middle and central portions of caudal fin (vs. absence of such stripes in S. affinis , S. brasiliensis , S. franciscanus , and S. hilarii ). Salminus santosi can be additionaly diagnosed from all congeners, except S. affinis and S. iquitensis , by the presence of a dark, straight postorbital stripe extending across the contact area between infraorbitals 4 and 5 to upper portion of opercle (vs. absence of postorbital stripe S. brasiliensis , S. hilarii , and S. franciscanus ). Salminus santosi can be additionally diagnosed from S. brasiliensis by presenting considerably lower scale counts, i.e., lateral line (61–74, modally 69, vs. 79–102, modally 96), and horizontal between dorsal-fin origin and lateral line (vs. 10–13, modally 11, vs. 14–18, modally 16), and by possessing color in life mainly silvery, with golden pigmentation restricted to facial bones and underside (vs. overall color golden in living specimens). Salminus iquitensis can be diagnosed from S. santosi by possessing lower scale counts, i.e., lateral line (61–74, modally 69, vs. 65–87, modally 75), and horizontal between dorsal-fin origin and lateral line (10–13, modally 11, vs. 11–14, modally 12), and higher anal-fin branched rays counts (18–24, modally 22, vs. 20–25, modally 23), and caudal-fin basis light-yellow, with distal portion typically rosy to light-red (vs. caudal-fin basis light-yellow, with middle and distal portions deep red). See the item “Remarks” below, for an additional discussion regarding the diagnosis of both species.

Description. Morphometric data presented in Table 8 . Middle-sized species, larger specimen examined 345.0 mm SL. Body elongated, largest body height at level of dorsal-fin origin. Dorsal profile slightly convex from snout tip to vertical through anterior nostril, straight to slightly concave from later point to tip of supraoccipital process, slightly convex from later point to dorsal-fin origin, straight along dorsal-fin basis, and slightly convex from dorsalfin terminus to adipose-fin origin. Dorsal profile of caudal peduncle slightly concave. Ventral profile slightly convex from tip of lower jaw to pelvic-fin insertion, straight to slightly convex from later point to anal-fin origin, and approximately straight along anal-fin basis. Ventral profile of caudal peduncle slightly concave.

Head profile acute anteriorly, mouth terminal. Maxillary elongated, extending posteriorly slightly beyond vertical through posterior eye margin. Adipose eyelid well developed. Premaxilla with two teeth rows. Teeth of outer row teeth considerably larger than those of inner series other than for second tooth of inner row. Outer row with 4–10 teeth, approximately equal in size; teeth with distinct, elongate basal portion (shaft), and apical portion (crown). Crown triangular, angles possibly constituting poorly differentiated cusps. Inner tooth row with 7–13 teeth, symphyseal tooth relatively large, second tooth slightly smaller, third and subsequent teeth considerably smaller. Teeth of inner row morphologically similar to those from outer row, except for proportionally shorter shafts and being more massive overall. Middle portion of ventral margin of maxilla slightly concave. Maxilla with 21–44 teeth, similar in shape to those from outer row of premaxilla, but slightly smaller and decreasing very gradually in size posteriorly, with less developed crowns, last teeth roughly conical. Dentary with 22–38 teeth on primary, outer row morphologically similar to those from outer row in premaxilla, and other than first to third teeth, slightly smaller than those on premaxilla. Remaining teeth gradually decreasing in size and presenting less developed crowns. Teeth of outer dentary row, outer premaxilla row, and maxilla with crowns slightly recurved lingually. Inner tooth row with 41–71 conical teeth arranged continuously from symphysis to terminus of inner rim of replacement teeth trench. Teeth at inner row oriented at right angle relative to teeth of primary row, with apices directed lingually.

Scales cycloid. Lateral line complete, extending from supracleithrum to caudal-fin base. Lateral line scales 61(1), 62(1), 63(2), 64(3), 65(1), 66(3), 67*(7), 68(3), 69(13), 70(8), 71(11), 72(10), 73(3), or 74(2). Laterosensory tubes simple, straight or deflected downward. Horizontal scale series between dorsal-fin origin and lateral line 10(9), 11*(51), 12(7), or 13(1). Horizontal scale series between lateral line and pelvic fin insertion 5(19), 6*(41), or 7(8). Circumpeduncular scales 20(7), 21(15), 22*(29), 23(16), or 24(1).

Dorsal-fin rays ii, 9, single specimen ii, 10. Dorsal-fin origin approximately midway between snout and hypural joint. First dorsal fin pterygiophore inserting behind neural spine of 14 th (1) or 15 th (2) vertebrae. Anal fin rays iv, 18(1), 19(1), 20(6), 21(18), 22*(30), 23(10), or 24(2). First anal fin pterygiophore inserting behind hemal spine of 24 th (1) or 25 th (2) vertebrae. Last unbranched rays and first to second branched anal-fin rays longer; third to ninth ray gradually shortening, with remaining rays approximately equal in size. Pectoral fin-rays i,12(10), 13(40), or 14*(17). Pelvic-fin rays i,7. Principal caudal-fin rays 10/9. Anal fin with small hooks along last unbranched ray and anteriormost branched anal-fin rays in 3 specimens (MZUSP 26524, 204.0 mm SL; MZUSP 40560, 163.5 mm SL; ZUEC 9124, 190.6 mm SL). Hooks limited to posterior branch of ray. Pelvic fins with hooks on branched rays 1–6 (MZUSP 26524), or 3–5 (MZUSP 40560), limited to posterior branch of ray. Scales sheath composed of two horizontal series covering basal portion of anal-fin rays. Caudal fin moderately forked to slightly emarginated. Laterosensory tube on caudal fin extending to caudal-fin terminus, with dorsally and ventrally oriented side branches along its length. Central caudal-fin extension present, small, discernible in specimens with well-preserved caudalfin margins, at level of main rays 10–11, where laterosensory tube ends.

Four branchiostegal rays. First gill arch with 14(1), 15(1), 17(2) lower gill-rakers, 14(2), 15(2) upper gill rakers and 1(4) at angle. Vertebrae 44(1), 45(2), 46(1). Supraneurals 11(1) or 12(1).

Color in alcohol. Overall color of specimens still retaining guanine grey dorsally, with plumbeous tint. Top of head (including supraorbital), snout and anterior portion of maxilla brown; remaining infraorbitals and opercle silvery. Maxilla, gular area and dentary light brown. Dark postorbital stripe approximately straight, extending across contact area between infraorbitals 4–5 to upper portion of opercle, formed by concentration of small dark chromatophores, variously developed but always present. Sides of body clear, with silvery hue, dark grey dorsally. Humeral blotch present, little conspicuous, oval-shaped, horizontally elongated, formed by pigmentation subjacent to scales, lying immediately above lateral line, at level of second to sixth scales. Narrow, straight dark stripes extending along trunk, formed by dark chromatophores concentrated at central-distal portion of each scale. Stripes present across all trunk, more conspicuous dorsally. Broad dark stripe across caudal peduncle, starting at middle portion of caudal peduncle, and gradually broadening towards caudal-peduncle terminus. Caudal-peduncle stripe extending into distal portion of four middle caudal-fin rays. Caudal fin with numerous, tiny stripes concentrated at the interradial membranes of middle and central portions of caudal fin, formed by rows of dark chromatophores. Anal, dorsal, pelvics, pectorals, and adipose fins clear, with few, scattered dark chromatophores. Specimens which lost guanine pigmentation as a result of long storage in formalin with overall color brown, lacking silvery pigmentation on sides of body, infraorbitals, or opercle.

Color in life. Description based on pictures of a specimen from the rio Itacaiúnas provided by M. Andrade, from a specimen from the middle rio Tocantins at the Lageado dam, provided by M.F.G. Brito, from a specimen from a tributary of rio Vermelho, near the city of Goiás, Goiás state, provided by J.B. Nunes, from the specimen ZUEC 14610, shortly after collection (provided by I. Fichberg and J. Muriel-Cunha), from a specimen from rio Parauapebas (MZUSP 106938), provided by M. Loeb, and from a photo from a specimen from the middle rio Araguaia basin ( Venere & Garutti, 2011:111). Sides of body clear, with silvery hue; dorsum grey. Facial bones and opercle silvery, with some golden/red pigmentation. Eye rim red. Caudal fin light yellow at basis, deep red at middle and distal portions. Dorsal, anal, pectorals, pelvics, and adipose fin yellowish at basis, with distal portions orangish to reddish. Dark markings as in preserved specimens, except that some longitudinal stripes with orangish to reddish pigmentation ( Fig. 16 ).

Sexual dimorphism. As described in the Description, fin hooks are present at pelvic and anal fins of mature males (MZUSP 26524, 204.0 mm SL; MZUSP 40560, 163.5 mm SL; ZUEC 9124, 190.6 mm SL).

Etymology. The specific name honors the ichthyologist Geraldo Mendes dos Santos, from INPA, and is in recognition of his great contribution to the knowledge of the fishes from the Brazilian Amazon, and particularly from the rio Tocantins basin. A patronymic adjective.

Common names: “dourado” ( Santos et al., 1984; Venere & Garutti, 2011); “rabo vermelho” ( Castelnau, 1855); “saicanga” ( Venere & Garutti, 2011); “sardinha-rabo-vermelho”; “sardinha rabo de ouro”; “matrinch ã” ( Begossi & Garavello, 1990); “tubarana” ( Ribeiro et al., 1995); “peĥirewawe” (Xavante language; Venere & Garutti, 2011).

Distribution. Salminus santosi is only known from the rio Tocantins basin, Brazil, where it is widely distributed ( Fig. 17 ).

Ecological notes, conservation. Salminus santosi is reported as favoring rapids ( Santos et al., 1984) and headwater areas ( Venere & Garutti, 2011). The smallest mature male examined (judging for the presence of hooks on the anal- and pelvic-fins) reached 163.5 mm SL (MZUSP 40560). Gut contents of one specimen (MZUSP 53620, 154.8 mm SL) contained a small, partially digested characid fish. Based on the examination of gut contents of several specimens collected at the upper rio Tocantins basin, Albrecht et al. (2012: 206) considered the species to be a piscivore. The species has a small importance for fisheries ( Santos et al., 1984; Garavello et al., 2010).

Remarks. Valenciennes (1850: 64–65), when describing Salminus hilarii , included in the type series specimens collected by Francis de Castelnau, only mentioning that they were collected “de les rivières de l’intérieur du Brésil ”. Castelnau (1855: 60) clarified the origin of the specimens collected by him as being “le rio Vermelho, qui traverse la ville de Goyaz”, i.e., within the rio Araguaia basin, Goiás, Brazil. Géry & Lauzanne (1990: 117) listed the typical series of Salminus hilarii , mentioning three specimens collected by Castelnau (although Valenciennes, 1850, mentioned only two), and designated one of the syntypes collected by Auguste de Saint-Hillaire in the rio S ã o Francisco, MNHN A.8658, as the lectotype of Salminus hilarii (see item “Remarks” of S. hilarii ). The specimens collected by Castelnau (MNHN A.9849), thus, became paralectotypes of Salminus hilarii . We have reexamined these latter specimens during the present study and, although poorly preserved, they still present a distinct dark post-orbital stripe, a feature only shared within the genus Salminus , with S. affinis and S. iquitensis , and clearly should be assigned to S. santosi . Salminus santosi has been misidentified in the literature as S. hilarii ever since (e.g., Santos et al., 1984; Venere & Garutti, 2011; Albrecht et al., 2012; Bartolette et al., 2017). More recently, Machado et al. (2017, 2018), sequencing both mitochondrial and nuclear markers of all of the then recognized Salminus species, identified the populations herein named as S. santosi as a distinct, unrecognized species, with 8.5 % divergence in the COI gene from the closest species, S. iquitensis (identified by these authors respectively as “ S. hilarii Araguaia ” and “ S. hilarii Amazon ”, respectively). Salminus santosi is very similar morphologically to S. iquitensis , from which differ from slightly distinct, although overlapping, scale and branched anal-fin rays counts (see Diagnosis and Tables 6–7 ). Both species can be additionally diagnosed by the color in life, with S. santosi presenting the caudal-fin with more intense and broad red pigmentation, while the caudal-fin in S. iquitensis is typically mostly light-yellow, with only the distal margin rosy. However, a deep red pigmentation is observed in some specimens of S. iquitensis , including specimens herein tentatively assigned to the species from the rio Branco basin (see item “Color in life” of the latter species). Both species also seem to differ in some other color features in life: the intensitiy of red pigmentation in dorsal, anal, pectoral, and pelvic fins is greater in S. santosi than in S. iquitensis , S. santosi possess a red eye rim (vs. light-yellow to olive in S. iquitensis ), and the golden pigmentation on facial bones and opercle is typically more developed in S. iquitensis than in S. santosi (compare Figs. 13 and 16 ). Although the morphological diagnosis between both species is based mainly in overlapping meristic features or color pattern features that are either overlapping or subtle, our evaluation is that there is enough evidence to corroborate the hypothesis of Machado et al. (2017, 2018) of the specific distinction between both taxa.

Material examined.

Type material. Holotype. MZUSP 34916 (293.0 mm SL), Brazil, Pará, Parauapebas, igarapé do Cinzento, rio Itacaiúnas , c. 5º51’S, 50º32’W; M. Goulding, Nov 1983.

Paratypes. All from Brazil, rio Tocantins basin. Goiás: MZUSP 40491 (4, 124.2– 156.8 mm SL), Flores de Goiás, rio Paranã (rapids), fazenda Olho d′Água , c. 14º31′S, 47º3′W; J.C. Oliveira & W.J.E.M. Costa, 12 Sept 1988 . MZUSP 40912 (3, 154.9– 170.6 mm SL), Flores de Goiás, Poço da Gandaia, rio Paran ã (lagoon), fazenda Olho d′Água, c. 14º31′S, 47º3′W; J. C. Oliveira & W.J.E.M. Costa, 21 Jan 1989. MZUSP 40560 (2, 163.5– 182.3 mm SL); MZUSP 40584 (4, 149.7–166.0 mm SL), Iaciara, rio Paranã, 8 km above ferry at road GO-112, c. 14º4′S, 46º53′W; J.C. Oliveira & W.J.E.M. Costa, 15 Sept 1988. MNRJ 13281 (1, 228.0 mm SL), Formosa, rio Paran ã, from mouth of rio Cangalha to bridge at road to Formosa , 15°25′41′′S, 47°17′57′′W; L.E.M. Cardoso, 3 April 1983 . MNRJ 17646 (2, 212.5– 224.9 mm SL), Minaçú / Colinas do Sul, rio Tocantins, below UHE Serra da Mesa , 13°49′S, 48°17′W; D.F. Moraes Jr., D.A. Halboth, O. T. Oyakawa et al., 28 Oct–4 Nov 1996 . MNRJ 12730 (1, 188.4 mm SL), Niquelândia, rio Acaba Saco , trib. rio Maranhão, c. 14º31′S, 48º56′W; G.W. Nunan & D.F. Moraes Jr., 8 Oct 1985 . MNRJ 12668 (1, 203.5 mm SL), Barro Alto / Niquelândia, Cachoeira do Machadinho , rio Maranhão, 14º38′36′′S, 48º59′14′′W; G.W. Nunan & D.F. Moraes Jr., 5 Oct 1985 . MNRJ 12583 (2, 186.1– 188.1 mm SL), Uruaçú, córrego Coati (trib. córrego Taquaral , trib. rio das Almas), road BR-135 (Belém-Brasília); G.W. Nunan & D.F. Moraes Jr., 7 Oct 1985 . MNRJ 12716 (1, 42.3 mm SL), Uruaçu, rio Palmeiras , trib. rio Maranhão, c. 13º55′S, 48º36′W; G.W. Nunan & D.F. Moraes Jr., 17 Oct 1985 . CAS 79289 (1, 278.0 mm SL), upper rio Maranhão, Água Quente , c. 14º36′S, 48º59′W; C. Ternetz, 16 Oct 1923 . CAS 24796 (1, 228.0 mm SL), “ Meninos R. into Rio Maranh ã o” [not located]; C. Ternetz, 1 Dec 1923 . MZUSP 26524 (2, 204.0–218.0 mm SL), rio Resende, trib. rio Vermelho, 10 km from Buenolândia , c. 15º42′S, 50º21′W; J.C. Garavello, A. Copriva & L.L. Ferreira, 7–13 Dec 1983 . MZUSP 52390 (2, 180.5– 180.9 mm SL), Nova Crixás, rio Araguaia, Bandeirantes , 13º41′S, 50º48′W; R.S.A. Matias, July 1997 . Tocantins: MZUSP 81106 (1, 179.9 mm SL), Conceiç ã o do Tocantins, rio Palma, near village of Taipas, road Dianópolis-Conceiç ã o do Tocantins, 12°22′8′′S, 47°2′31′′W; C. R. Moreira, J.C. Nolasco & M. Avila, 1 Aug 2002 . Pará: INPA 12283 (3, 154.0– 182.3 mm SL), rio Tocantins, Jatobal , c. 4º32′S, 49º28′W; Eq. Ictiologia / INPA, 5 July 1982 . INPA 16794 (2, 153.2–217.0 mm SL), rio Tocantins, igarapé Valentim , Tucuruí-Marabá road, km 130; G.M. Santos, 6 July 1982 . INPA 12282 (4, 135.2– 162.3 mm SL), rio Tocantins, Porto Castanheiro, Tucuruí; G.M. Santos, 4 May 1982 . MZUSP 26925 (3, 1 c&s, 101.6–141.8 mm SL), Marabá , rio Tocantins, c. 5º19′S, 49º4′W; N.J.H. Smith, April 1979 . MZUSP 105505 (1, 245.0 mm SL) ; ZUEC 14610 (1, 345.0 mm SL), Marabá, rio Tapirapé, Tatuz ã o field base, Reserva Biológica Tapirapé , 5º36′47′′S, 50º26′42′′W; J.M. Cunha & I. Fichberg, 9 Aug 2008 . ZUEC 9124 (2, 190.6–206.0 mm SL), Marabá, rio Tapirapé, sítio Cachoeirinha , Reserva Biológica Tapirapé , 5º31′50′′S, 50º39′59′′W; J.M. Cunha & I. Fichberg, Dec 2008 . MZUSP 34915 (1, 320.0 mm SL), rio Itacaiúnas, Caldeirão , 5º52′S, 50º29′W; M. Goulding, April–May 1983 . MZUSP 34918 (2, 180.2–259.0 mm SL), Parauapebas, rio Itacaiúnas, Cachoeira Carreira Com- prida, c. 5º52′S, 50º29′W; M. Goulding, Nov 1983 . MZUSP 34913 (8, 194.5–336.0 mm SL), igarapé Águas Claras, rio Itacaiúnas , c. 5º52′S, 50º29′W; M. Goulding, Nov 1983 . MZUSP 34917 (3, 253.0–305.0 mm SL), Parauapebas, igarapé Boa Vista, rio Itacaiúnas , c. 5º52′S, 50º29′W; M. Goulding, Nov 1983 . MZUSP 58220 (1, 178.7 mm SL), Parauapebas, rio Itacaiúnas , 5°52′29′′S, 50°29′20′′W; P.S. Pompeu, Sept 1997 . MZUSP 58047 (1, 161.4 mm SL), Parauapebas, igarapé Salobo (trib. rio Itacaiúnas ), 5°46′50′′S, 50°32′48′′W; P.S. Pompeu, July 1997 . INPA 20519 (2, 224.0–287.0 mm SL), Canaã de Carajás, rio Sossego, afl. rio Parauapebas , c. 6º24′S, 50º4′W; R. Pinto , 5 Sept 2002 . MZUSP 106938 (3, 1 skel., 186.0– 205 mm SL), Canaã de Carajás, rio Parauapebas, below Poço do Jaú , 6º23′15′′S, 50º2′23′′W; M. Loeb & H . R. Varella , 21 June 2010 .

Not types of Salminus santosi . MNHN A.9849 (3, 276.2– 356.3 mm SL), “Goyaz, Deville & Castelnau” ( Brazil, state of Goiás, Goiás, rio Vermelho, tributary of rio Araguaia ; F. de Castelnau & E. Deville, March–April 1844; cf. Castelnau, 1855: 60; paralectotypes of Salminus hilarii Valenciennes ) .

Not types: All from Brazil, rio Tocantins basin. Goiás: LBP 25625 (1, 149.2 mm SL), Porangatu, rio do Ouro (trib. rio Santa Teresa ), 13º24′12′′S, 48º59′50′′W; R. Devidé, B. Melo, C. Araya & G.S.C. Silva, 25 Nov 2017. MZUSP 52309 (1, 201.0 mm SL), rio Araguaia [precise locality not specified]; R.S.A. Matias, July 1997. MZUSP 53620 (2, 1 C&S, 155.3–204.0 mm SL), rio Araguaia [no specific locality]; R.A.S. Silvano, 1997–1998. Pará: MZUSP 34914 (17, 154.7– 362.2 mm SL), rio Itacaiúnas, Caldeirão , c. 5º52′S, 50º29′W; M. Goulding, June–July 1983. ZUEC 15900 (1, 174.8 mm SL), Parauapebas, igarapé Salobo , 5º45′52′′S, 50º33′30′′W; T. Giarizzo et al., 14 Sept 2009 .

Figures

FIGURE 13. Salminus iquitensis, living specimens: (A) Peru, Ucayali, río Aguaytia; (B) ROM 93073, Ecuador, Paztaza, río Bobonaza; (C) CZUT-IC 7147, 133.6 mm SL: Colombia, Guaviare, Río Guayabero basin; (D) IAvH-P 17096, Colombia, Meta, Río Guayabero. Photo A by A. Linares, B by N.K. Lujan, C by A. Urbano-Bonilla, D by Mark Sabaj.

FIGURE 15. Salminus santosi: (A) MZUSP 34916, holotype, 293.0 mm SL, Brazil, Pará, igarapé do Cinzento; (B) MZUSP 26524, 204.0 mm SL, paratype, Brazil, Goiás, rio Vermelho.

FIGURE 16. Salminus santosi, living specimens: (A) Brazil, Goiás, rio Vermelho; (B) Brazil, Pará, rio Itacaiúnas. Photo A by M. Andrade, B by J.B. Nunes.

FIGURE 17. Map of the rio Tocantins basin, Brazil, showing the distribution of S. santosi (red dots; red star indicates the typelocality).