Psalidodon canaaensis, Queiroz & Silva & Machado & Assis & Barros & Dergam & Henschel, 2025

Queiroz, Victor De, Silva, Priscilla Caroline, Machado, Valéria Nogueira, Assis, Cidimar Estevam De, Barros, Lucas Caetano, Dergam, Jorge Abdala & Henschel, Elisabeth, 2025, A new endemic species of Psalidodon Eigenmann (Characiformes: Acestrorhamphidae) from the upper rio Doce basin, Brazil, Zootaxa 5725 (2), pp. 231-254 : 234-241

Psalidodon canaaensis , new species Queiroz, Henschel & Silva urn:lsid:zoobank.org:act:

( Figs. 1–3 ; Table 1)

Psalidodon sp. — Queiroz et al., 2023: 17 (listed, comparative material). Holotype. MZUFV 2574 , female, 76.3 mm SL, Brazil, Minas Gerais State, municipality of Canaã, downstream Cachoeira Grande on rio Santana , tributary of rio Casca , upper rio Doce basin, 20°36’22”S 42°36’17”W, J. L. Pontes & C. Rocha, 23 Dec 1997. COI sequence: GenBank accession PV707849.

Paratypes: All from Brazil, Minas Gerais State, municipality of Canaã, rio Santana , tributary of rio Casca , upper rio Doce basin: MZUFV 13329, 9 alc, 71.5–83.6 mm SL, 2 c&s, 74.5–78.2 mm SL, collected with the holotype. MZUFV 5347, 14 alc, 30.9–81.3 mm SL, 1 c&s, 85.2 mm SL, downstream Cachoeira Grande , 20°36’22”S 42°36’16”W; collectors and date of collection unknown. UFMG-ICT 3987 (ex. MZUFV 5359 ), 4 alc, 27.0– 84.7 mm SL, downstream Cachoeira Grande , 20°36’22”S 42°36’16”W; collectors and date of collection unknown. UFRGS 30197 (ex. MZUFV 12631 ), 3 alc, 36.7–85.7 mm SL, downstream Cachoeira Grande , 20°36’21”S 42°36’14”W, J. L. Pontes & G. M. Prado, 23 Sept 1997 . MZUFV 13341, 1 alc, 70.9 mm SL, upstream Cachoeira Grande, 20°36’16.8”S 42°36’03.6”W, V. de Queiroz, C. E. Assis, L. Barros & V. Comastri, 24 Feb 2025 .

Diagnosis. Psalidodon canaaensis can be distinguished from some of its congeners by having a complete lateral line [ vs. incomplete lateral line in P. anisitsi (Eigenmann) , P. balbus (Myers) , P. crenuchoides (Zarske & Géry) , P. hamatus (Bertaco & Malabarba) , P. kalunga (Bertaco & Carvalho) , P. langeanii (Lima & Moreira) , P. pessalii Teixeira , Salvador, Mirande & Lima, P. togoi (Miquelarena & López) , P. uaiso (Carvalho & Langeani) , and P. uberaba (Serra & Langeani) ]. The number of perforated lateral line scales (35–36) distinguishes P. canaaensis from P. alleni (Eigenmann & McAtee) , P. correntinus (Holmberg) , P. erythropterus (Holmberg) , P. gymnodontus , P. gymnogenys (Eigenmann) , P. henseli (Melo & Buckup) , P. parahybae (Eigenmann) , P. pelegrini (Eigenmann) , P. rutilus (Jenyns) , P. saguazu (Casciotta, Almirón & Azpelicueta) , P. scabripinnis , P. schubarti (Britski) , P. serratus (Garavello & Sampaio) , P. varzeae (Abilhoa & Duboc) , and P. xiru (Lucena, Castro & Bertaco) , that have 37 or more perforated scales, and from P. vermilion (Zanata & Camelier) , which has fewer than 35. Psalidodon canaaensis differs from P. eigenmanniorum (Cope) by having 5 scales rows between lateral line and pelvic-fin origin ( vs. 4 in P. eigenmanniorum ), and from P. bifasciatus (Garavello & Sampaio) , P. endy (Mirande, Aguilera & Azpelicueta) , P. henseli , P. pampa (Casciotta, Almirón & Azpelicueta) , P. troya (Azpelicueta, Casciotta & Almirón) , by having 13-14 scales rows around caudal peduncle ( vs. 15 or more). Psalidodon canaaensis is further distinguished from P. crenuchoides , P. kalunga , P. pessalii , and P. uberaba by the presence of an adipose fin ( vs. absence). Psalidodon canaaensis also differs from P. bifasciatus , P. bockmanni (Vari & Castro) , P. chico (Casciotta & Almirón) , P. cremnobates (Bertaco & Malabarba) , P. dissensus (Lucena & Thofehrn) , P. eigenmanniorum , P. endy , P. gymnodontus , P. hamatus , P. henseli , P. leonidas (Azpelicueta, Casciotta & Almirón) , P. marionae (Eigenmann) , P. ojiara (Azpelicueta & Garcia) , P. pampa , P. pessalii , P. powelli (Terán, Butí & Mirande) , P. puka (Mirande, Aguilera & Azpelicueta) , P. pynandi (Casciotta, Almirón, Bechara, Roux & Ruíz Díaz) , P. rivularis , P. saguazu , P. togoi , P. troya , P. tumbayaensis (Miquelarena & Menni) , P. varzeae , P. xavante (Garutti & Venere) and P. xiru by having a single humeral blotch ( vs. two); from P. correntinus , P. langeanii , P. laticeps (Cope) , P. pelegrini , P. uaiso , and P. vermilion by its vertically elongated humeral blotch ( vs. horizontally rounded); and from P. hermosus (Miquelarena, Protogino & López) , which has a Y-shaped humeral blotch. Additionally, P. canaaensis differs from P. alleni and P. powelli by the presence of maxillary teeth ( vs. absence), and by having maxillary teeth with three to five cusps ( vs. seven or more cusps in P. correntinus , P. dissensus , P. ita (Almirón, Azpelicueta & Casciotta) , P. ojiara , P. puka , and P. togoi ). Psalidodon canaaensis differs from P. bockmanni and P. pelegrini by having 4 teeth in the premaxillary outer row (vs. 5 or more), and from P. togoi by having 4 (vs. 3). Dentary teeth decrease abruptly posterior to the fourth tooth in P. canaaensis (vs. decreasing gradually in P. pynandi ). The number of branched anal-fin rays (18–24) distinguishes P. canaaensis from species with more than 25 branched anal-fin rays ( P. alleni , P. correntinus , P. erythropterus , P. pelegrini , P. saguazu and P. schubarti ), and from species with up to 17 branched anal-fin rays ( P. brachypterygium (Bertaco & Malabarba) , P. crenuchoides , P. cremnobates , P. goyanensis (Miranda-Ribeiro) , P. kalunga , P. paranae (Eigenmann) , P. pessalii , P. uaiso and P. uberaba ). Additionally, males of P. canaaensis can be distinguished by having bony hooks on the anal fin ( vs. absent in P. biotae (Castro & Vari) , P. gymnodontus , P. gymnogenys , P. saguazu , P. uaiso , P. uberaba , P. varzeae , and P. xavante ); by having bony hooks on the pelvic fins ( vs. absent in P. correntinus , P. goyanensis , and P. vermilion ); by lacking bony hooks on the caudal fin ( vs. present in P. chico , P. hermosus , P. leonidas , P. ojiara , P. pynandi , P. togoi , and P. troya ); by lacking bony hooks on the pectoral fins [ vs. present in P. jequitinhonhae (Steindachner) ]. Psalidodon canaaensis differs from P. minor (Garavello & Sampaio) and P. dissimilis (Garavello & Sampaio) by having the greatest body depth at vertical through dorsal-fin origin ( vs. anterior to dorsal-fin origin). Psalidodon canaaensis differs from P. tumbayaensis by its light pigmentation of body scales ( vs. reticulated pattern on body scales). Psalidodon canaaensis is distinguished from P. fasciatus by the absence of an elongated filament on first dorsal-fin ray in males ( vs. present), and by the presence of one hook per ray segment on the pelvic fin ( vs. two), and by having fewer than 25 branched anal-fin rays ( vs. more than 25). Psalidodon canaaensis differs from P. rivularis by having a single humeral blotch ( vs. two), by having light pigmentation on body scales ( vs. reticulated pattern on body scales in P. rivularis ), and by having the greatest body depth at vertical through dorsal-fin origin (vs. posterior to dorsal-fin origin in P. rivularis ).

Description. Morphometric data presented in Table 1. Body compressed and moderately elongated, with highest body depth at vertical through dorsal-fin origin. Dorsal profile of head smoothly convex from upper lip to vertical through anterior margin of orbit; nearly straight or smoothly concave from that point to tip of supraoccipital spine. Dorsal body profile slightly convex from tip of supraoccipital to dorsal-fin base; straight and slanted dorsoposteriorly along base of dorsal fin to origin of adipose fin, slightly convex at base of adipose fin; slightly concave from latter point to origin of anteriormost dorsal procurrent caudal-fin ray. Ventral profile of head nearly straight from anterior tip of dentary to pectoral-fin insertion. Ventral body profile convex from pectoral-fin insertion to pelvic-fin insertion, and straight from that point to anal-fin origin, nearly straight along anal-fin base, and nearly straight from that point to origin of anteriormost ventral procurrent caudal-fin ray.

Head small, average head length slightly more than one-quarter of the standard length.Snout length approximately one fourth of head length and smaller than eye diameter. Eye diameter length approximately one third of head length. Mouth terminal. Maxilla positioned at nearly 60° angle; posteriormost margin positioned at vertical through anterior border of pupil when mouth closed. Anteroventral margin of maxilla convex, posterodorsal margin concave. Third infraorbital large, almost reaching preopercle, leaving small posteroventral naked area.

Premaxillary teeth in two rows; outer row with 4(15) teeth with three or five cusps, with central cusp longer. Inner row with 5(14) teeth; symphyseal tooth asymmetrical, with one or two shorter cusps on medial side near symphysis, followed by one longest cusp and two or three shorter cusps on lateral side of tooth; second tooth largest; second to fourth teeth bearing five to seven cusps, usually seven cusps; last tooth abruptly smaller with three to five cusps, usually five. Maxilla with 1*(16) tooth, rarely 2(2), with three to five cusps, central cusp longest. Four anteriormost dentary teeth larger, with five to seven cusps (16), followed by an intermediary tooth, with three to five cusps (13), usually three cusps, and usually five to seven smaller tricuspid or conical teeth ( Fig. 2 ).

Dorsal-fin rays iii,9(28). First unbranched dorsal fin-ray only visible in c&s specimens; second one-half length of third unbranched ray. Distal margin of dorsal fin convex. Dorsal-fin origin approximately at middle of standard length (SL) and slightly posterior to vertical through pelvic-fin origin. Adipose fin present. Anal-fin rays iv-v,18(1), 19(4), 20(6), 21*(9), 22(6), 23(1), 24(1). Anal-fin distal border concave; anteriormost branched rays longer forming anterior lobe. Anal-fin origin located at vertical through two scales posterior to insertion of last dorsal fin-ray. Pectoral-fin rays i,11(3), 12(8), 13*(14), 14(4), 15(1). Pectoral-fin tip reaching pelvic-fin insertion. Pelvic-fin rays i,7(28). Pelvic-fin origin anterior at vertical through dorsal-fin origin. Caudal fin forked with 19(22) principal rays, lobes similar in size.

Lateral line slightly curved anteriorly, completely pored, with 35*(6) or 36(12) scales. Horizontal scale rows between dorsal-fin origin and lateral line 6(25). Horizontal scale rows between lateral line and pelvic-fin origin 5(26). Predorsal scales 10(2), 11(9), 12*(12), 13(1) arranged in regular series. Scale rows around caudal peduncle 13(4), 14*(20). Scale sheath along anal-fin base formed by eight to ten scales in single series and covering base of anteriormost rays.

Supraneurals 5(1) or 6(2). Dorsal pterygiophores 10(3), anal pterygiophores 21(3). Total vertebrae 34(1), 35(1), or 37(1): abdominal vertebrae 17(2) or 18(1), and caudal vertebrae 17(1), 18(1), or 19(1). First dorsal-fin pterygiophore inserted posterior to neural spine of 10th(3) vertebra, first anal-fin pterygiophore inserted posterior to haemal spine of 18th(1) or 19th(2) vertebrae. Eleven (3) dorsal and 10(3) ventral procurrent caudal-fin rays. Upper branch gill-rakers 8+1(2), lower branch 12(1) or 13(1).

Coloration in alcohol. ( Figs. 1 , 3 ). Dorsal and dorsolateral portions of head light brownish to brown, with scattered brown chromatophores. Infraorbitals yellowish, preopercle and opercular bones silvery, with few, scattered brown chromatophores, mainly concentrated on dorsolateral portions. Lips dark brown, snout with high concentration of brown chromatophores. Upper jaw dark brown, with high concentration of brown chromatophores in dorsolateral portion. Dorsal and dorsolateral portions of body light brown, dark chromatophores widespread dorsally, ventrally with few chromatophores. Conspicuous dark brown mid-lateral stripe covering one to two longitudinal series of scales, extending horizontally from two scales after humeral blotch to posterior margin of inner caudal-fin rays, dorsally and centrally expanded at posterior margin of caudal peduncle. Dark humeral blotch, vertically elongated, approximately two scales wide above the lateral line, broader in this region, narrowing to about half to one scale wide below the lateral line. Fins hyaline, with scattered brown chromatophores, mainly concentrated on first rays and distal portion of fins.

Coloration in life. ( Fig. 3 ). Ground color olive green and light brown dorsally, and silvery to white ventrally. Silvery midlateral band, with black chromatophores, covering one to two longitudinal series of scales and extending horizontally from two scales after humeral blotch; from that point to posterior margin of inner caudal-fin rays coalescing into a conspicuous dark brown mid-lateral stripe, dorsally and centrally expanded at posterior margin of caudal peduncle. Dorsal portion of iris yellow, with small red area on top. First to 4th infraorbital silvery, 5th and 6th infraorbital light brown, with scattered dark chromatophores. Preopercle dorsally light brown with scattered dark chromatophores, and silvery ventrally. Opercle silvery and olive green, plumbeous dorsolaterally. Dark humeral blotch clearly discernible as in preserved specimens. Pectoral, dorsal and adipose fins light olive green proximally and hyaline distally. Anal-fin olive-green on unbranched rays and first seven branched rays; posterior portion hyaline. Caudal-fin light olive-green on anterior half, light red on posterior portion, with fin tips hyaline.

Sexual dimorphism. Bony hooks were observed on distal margins of pelvic (MZUFV 5347, 85.3 mm SL) and anal fins (UFRGS 30197, 85.7 mm SL; MZUFV 5347, 38.9 mm SL) only in males. Anal fin with elongated bony hooks, one per segment of each lepidotrichia, more numerous from the last unbranched ray to first nine branched rays, on median and distal portions of the rays. Smaller and less numerous hooks restricted to the medial and distal parts of the branched portion of the remaining anal-fin rays, with the number of hooks decreasing posteriorly. Hooks nearly straight with a rounded base and distal end directed laterodorsally nearly parallel to ray axis. Pelvic fin with elongated bony hooks present only on medial ray branches, one per segment, positioned ventrally and oriented medially; hooks nearly straight with a rounded base and distal end directed to the fin ray base end, nearly parallel to ray axis ( Fig. 2 ). Small breeding tubercles on the dorsal region of the head and on the infraorbitals are found in the same males mentioned above.

Distribution. Psalidodon canaaensis is known only from the rio Santana, both downstream and upstream of the Cachoeira Grande, in the municipality of Canaã, Minas Gerais State, Brazil. The Cachoeira Grande is a>40 meters high waterfall located within an Environmental Protection Area (Área de Proteção Ambiental – APA). The rio Santana originates in the mountainous region of the Parque Estadual da Serra do Brigadeiro (PERD) and flows for approximately 30 km before its confluence with the rio Casca, within the upper rio Doce basin ( Fig. 4 ).

Ecological notes. ( Fig. 5 ). Psalidodon canaaensis inhabits the rio Santana, in the region of Cachoeira Grande, where the river bottom is composed by rocks, rubble, sand, and mud. Specimens were collected at altitudes ranging from approximately 1,010 to 1,050 meters a.s.l.. The rio Santana at the region of the type locality is 10–25 m wide, and around 0.5–2 m deep, presenting clear water. In the Cachoeira Grande region, the rio Santana flows through pastureland and is almost devoid of riparian vegetation. The stomach contents of the three cleared and stained specimens revealed the presence of plant fragments and insects of the Order Hymenoptera ( Formicidae ).

Etymology. The specific epithet “ canaaensis ” refers to the location where the species is found, namely the municipality of Canaã, in Minas Gerais State, Brazil. An adjective.

Conservation status. Psalidodon canaaensis is a restricted-range species, endemic to the rio Santana, and only known from two nearby localities: upstream and downstream of Cachoeira Grande. Despite recent collection efforts undertaken in the area (see Discussion), the rio Santana is still poorly sampled. The species occurs within a recently established municipal protected area (APA), but the surrounding habitat is degraded, with extensive pasture, cattle activity, and previous anthropogenic pressures, including local tourism, which contributes to pollution of the rio Santana and its surroundings (J. Dergam, pers. obs.).

Two unsuccessful dam construction proposals in 1997 and 2017, respectively, were halted due to the mobilization of local residents, researchers from the Universidade Federal de Viçosa (UFV), and NGOs, who organized protests and later founded the Associação de Moradores e Amigos da Cachoeira Grande (AMA Cachoeira Grande). This movement resulted in the establishment of an Environmental Protection Area (APA) in 2022, following a public consultation conducted by the municipal government in response to the association’s demands.

A total of only 34 specimens are known to date, all from the same location. Therefore, our data indicate that P. canaaensis potentially meets the thresholds for a threatened category, according to the IUCN Red List criteria (2024).

Figures

FIGURE 1. Psalidodon canaaensis, holotype, MZUFV 2574, female, 76.3 mm SL, Brazil, Minas Gerais State, municipality of Canaã, downstream Cachoeira Grande on rio Santana, tributary of rio Casca, rio Doce basin. Scale bar = 1 cm.

FIGURE 2. Paratypes of Psalidodon canaaensis. A. MZUFV 13329, 74.5 mm SL, female.Top left, lateral view of premaxillary teeth and maxillary tooth; bottom, medial view of dentary teeth; B. MZUFV 5347, 85.3 mm SL, male: details of bony hooks on pelvic-fin; C. MZUFV 13329, 78.2 mm SL, male: rhinosphenoid bone, showing the absence of a dorsal projection between the olfactory nerves (black arrow). Scale bar = 1 mm.

FIGURE 3. Psalidodon canaaensis. Top: MZUFV 13341, female, 70.9 mm SL, live specimen, upstream Cachoeira Grande on rio Santana, tributary of rio Casca, rio Doce basin; bottom: MZUFV 5347, male, 74.4 mm SL, preserved specimen, downstream Cachoeira Grande. Scale bar = 1 cm.

FIGURE 4. Distribution of Psalidodon canaaensis (red dot) in the rio Santana, upper rio Doce basin. MG= Minas Gerais State, eastern Brazil.

FIGURE 5. Type-locality of Psalidodon canaaensis in the rio Santana, a tributary of rio Casca, upper rio Doce basin; A. Signboard of Área de Proteção Ambiental (APA) of Canaã, where the Cachoeira Grande is located; B. Cachoeira Grande; C. Downstream of Cachoeira Grande; D and E. Upstream of Cachoeira Grande. Photos by V. de Queiroz (A); L. Barros (B-C); C. Assis (D-E).