Hyphessobrycon citrus, Marinho & Dagosta, 2024

Marinho, Manoela Maria Ferreira & Dagosta, Fernando Cesar Paiva, 2024, Redescription of Hyphessobrycon cachimbensis (Characiformes: Characidae) with the description of a new congener from the Serra do Cachimbo, Brazil, Neotropical Ichthyology (e 230127) 22 (2), pp. 1-20 : 11-16

Hyphessobrycon citrus , new species urn:lsid:zoobank.org:act:740F2376-F8F3-4F82-A511-04B5DF262D35

( Figs. 6–8 ; Tab. 2)

Hyphessobrycon cachimbensis non Travassos, 1964. —Birindelli et al., 2009: fig. 5 (rio Tapajós basin). —Marinho et al., 2014:263 (rio Tapajós basin, listed as comparative material). —Pastana, Dagosta, 2014:394 [rio Tapajós basin, listed as comparative material (MZUSP 101429 not 101249)]. —Dagosta et al., 2016:258 (rio Tapajós basin, listed as comparative material). —Pastana, Ohara, 2016:396 (rio Tapajós basin, listed as comparative material).

Hyphessobrycon cf. cachimbensis . —Ohara et al., 2017:249 (listed under comparative material).

Hyphessobrycon sp. —Hoffman, Hoffmann, 2012:39 (image indicated as “ Hyphessobrycon sp. “Schwarzstreifen- Rotauge”. —Marinho et al., 2021:15 (information on lateral-line scale morphology).

Holotype. MZUSP 128236 , 38.0 mm SL, Brazil, Pará State, Novo Progresso, rio Tapajós basin, rio Teles Pires basin, tributary of rio Braço Norte at bridge on BR-163 road, near FAB military base, 09º28’20”S 54º52’11”W, 22 Jan 2009, A. L. Netto-Ferreira, J. L. O. Birindelli, L. M. Sousa & P. Hollanda-Carvalho.

Paratypes. All from Brazil, Pará, Novo Progresso, rio Tapajós basin, rio Teles Pires drainage. INPA 52183 , 10 , 27.2–43.4 mm SL, MCP 49451 , 10 , 27.0– 43.5 mm SL, MUBIO 182 , 15 , 20.1–35.2 mm SL, MZUEL 14350 , 10 , 24.4–40.8 mm SL, MZUSP 96823 , 561 , 16.2–48.5 mm SL (18, 37.5–48.5 mm SL), MZICT 3630 , rio Braço Norte drainage, tributary of rio Peixoto de Azevedo at bridge on BR-163 road, near FAB, 09º25’55”S 54º52’11”W, 19 Oct 2007, J. L. O. Birindelli, A. L. Netto-Ferreira, M. H. Sabaj & N. Lujan. MZUSP 96847 , 10 , 34.9–39.9 mm SL (2, 34.7–38.9 mm SL), 3 c&s, 33.9–35.7 mm SL, rio Braço Norte drainage, tributary of rio Peixoto de Azevedo at bridge on BR-163 road, near FAB, 09º28’20”S 54º52’11”W, 19 Oct 2007, J. L. O. Birindelli, A. L. Netto-Ferreira, M. H. Sabaj & N. Lujan. MZUSP 101429 , 13 , 23.1 – 41.0 mm SL (10, 27.9–41 mm SL), 1 c&s, 34.8 mm SL, same data as holotype. MZUSP 116590 , 42 , 17.3–42.4 mm SL, rio Braço Norte at BR-163 road, near divide between Pará and Mato Grosso State, 09º28’19.9”S 54º51’21.7”W, 5 Nov 2014, W. M. Ohara. MZUSP 128237 , 20 , 14.2–34.9 mm SL, tributary of rio Braço Norte near BR-163 road, 09°24’5.3”S 54°50’52.9”W, 4 Aug 2015, F. C. P. Dagosta, M. M. F. Marinho, P. Camelier & V. Giovanetti .

Diagnosis. Hyphessobrycon citrus can be distinguished from its congeners, except H. cachimbensis , H. chiribiquete , H. comodoro , H. cyanotaenia , H. fernandezi , H. melanostichos , H. nigricinctus , H. paucilepis , H. petricolus , H. piranga , H. psittacus , H. scholzei , H. sovichthys , H. stegemanni , H. taphorni , H. tuyensis , and H. vilmae , by the presence of a well-defined, relatively narrow dark midlateral stripe on body, from immediately behind the opercular opening to the tip of middle caudal-fin rays (vs. longitudinal stripe absent, stripe starting approximately at vertical through the dorsal-fin origin, or midlateral dark stripe becoming blurred towards the caudal peduncle). It can be distinguished from the aforementioned species, except H. cachimbensis , H. chiribiquete , H. comodoro , H. cyanotaenia , H. melanostichos , H. nigricinctus , and H. petricolus , by the presence of a humeral spot (vs. absence). Hyphessobrycon citrus can be distinguished from H. cachimbensis , H. comodoro , H. cyanotaenia , and H. melanostichos by having the longitudinal black stripe starting immediately behind the opercle (vs. starting at the posterior margin of orbit), from H. chiribiquete , H. nigricinctus and from H. cachimbensis by having 14–17 anal-fin rays (vs. 18 or more), and from H. petricolus by having 14 horizontal scale rows around caudal peduncle (vs. 12) and non-symphyseal teeth of the premaxillary inner row with 7 to 9 cusps (vs. 3 to 5). The yellow citrus coloration and a vivid colored red eye in life also help distinguishing H. citrus from congeners.

Description. Morphometric data in Tab. 2. Small characid species, largest recorded specimen with 48.5 mm SL. Body compressed, moderately elongate. Greatest body depth slightly anterior to dorsal-fin origin. Dorsal profile of head convex from upper lip to vertical through anterior nostril; straight to slightly convex from that point to tip of supraoccipital spine. Dorsal profile of body slightly convex along predorsal region, straight along dorsal-fin base, convex from terminus of dorsal-fin base to adipose-fin origin, and concave along caudal peduncle. Ventral profile of head and body slightly convex from tip of lower jaw to pectoral-fin origin, convex from that point to pelvic-fin origin, straight from that point to anal-fin origin, convex along anal-fin base in males and roughly straight in females (see Sexual dimorphism), and concave along caudal peduncle.

Upper and lower jaws anteriorly aligned, mouth terminal. Premaxillary teeth in two rows ( Fig. 8 ). Outer row with 2(1), 3*(26), 4(2), or 5(1) teeth, bearing five cusps. Inner row with 5*(28) or 6(2) teeth, with seven to nine cusps except symphyseal teeth, bearing six cusps. Posterior tip of maxilla extending to vertical through posterior half of second infraorbital. Maxilla with 2*(24), or 3(6) teeth, with five to seven cusps. Dentary with 5*(30) larger teeth with seven cusps, followed by one smaller tooth with five cusps (one specimen with a smaller tricuspid tooth), and by four to five diminutives, conical to tricuspid teeth. Central median cusp more developed than lateral cusps in all cuspidate teeth. Four branchiostegal rays (4). First gill arch with 3(4) gill rakers on hypobranchial, 9(4) rakers on ceratobranchial, 1(4) rakers on intermediate cartilage, and 6(4) rakers on epibranchial.

Scales cycloid, with 5 to 9 radii, from focus to posterior border of scales; circuli weakly developed proximally and absent distally. Total scales in the longitudinal lateral series 31(3), 32(10), or 33*(9). Scales on the lateral series variably perforated. Twenty specimens with 10(1), 11(1), 12(1), 13*(6), 14(4), 15(2), 16(1), 17(2), or 19(2) pored scales, followed by non-pored ones (incomplete lateral line) and two specimens with pored scales interspersed with non-pored ones (discontinuous lateral line), as follows: 11 pored + 2 non-pored + 2 pored + 17 non-pored and 19 pored + 3 non-pored + 2 pored + non-pored. Longitudinal scale rows between dorsal-fin origin and lateral line 5(15) or 6*(11). Longitudinal scale rows between lateral line and pelvic-fin origin 4*(21) or 5(9). Predorsal scales 10(9), 11(17), or 12(1), in single series. Horizontal scale rows around caudal peduncle 14*(28). Base of anteriormost anal-fin rays covered by a series of 3 to 5 scales. Caudal fin not scaled.

Supraneurals 5(3), with dorsal bony lamellae. Dorsal-fin rays ii,9*(23). Dorsal-fin rays ii*(30), 8(2) or 9(28). Proximal tip of first dorsal-fin pterygiophore inserted posterior to neural spine of 10 th (4) vertebra. Pectoral-fin rays i*(29), 10(6), 11(22), or 12(1). Pelvic-fin rays i*(30), 7*(29) or 8(1). Adipose-fin origin at vertical through base of 11 th to 13 th branched anal-fin rays. Anal fin falcate, with iv(3), 14(11), 15(7), 16*(15), or 17(1) rays. Proximal tip of first anal-fin pterygiophore inserted posterior to haemal arch of 17 th (2) or haemal spine of 17 th (2) vertebra. Dorsal procurrent caudal-fin rays 9(1), 11(2), or 12(1). Ventral procurrent caudal-fin rays 8(1), 9(2), or 10(1). Caudal-fin with i*(29), 8(1) or 9*(28) rays on upper and i*(29), 8*(29), rays on lower lobe. Caudal fin forked with similar sized lobes. Total vertebrae 33(4): precaudal vertebrae 17(4) and caudal vertebrae 16(4).

Coloration in alcohol. Overall ground coloration of head and body beige ( Fig. 7 ). Dorsal portion of head and body darker. Specimens usually with slight reticulated pattern on uppermost three horizontal scale rows, formed by concentration of chromatophores on the posterior portion of scales. Dark chromatophores concentrated at upper and lower jaws. Infraorbital series with only sparse chromatophores, except for the 5 th and 6 th infraorbitals, which are scattered dark pigmentated. Upper half of opercle with scattered pigmentation. Humeral blotch faint, with diffuse borders, encompassing approximately two scales horizontally and three vertically. Dark midlateral stripe on body one scale wide, extending from immediately behind the opercular opening to tip of middle caudal-fin rays. Abdominal region with only sparse chromatophores; scattered dark chromatophores above anal fin. Dorsal and anal fins with scattered dark chromatophores in interradial membranes. Pectoral and pelvic fins with hyaline, except for dark chromatophores scattered along edge of lepidotrichia. Adipose fin with sparse dark chromatophores. Outermost upper and lower caudal-fin rays with dark chromatophores along its entire length, remaining rays with scattered dark pigmentation. Caudal-peduncle blotch absent.

Coloration in life. Dark chromatophores pattern described in Color in alcohol section. Overall body coloration yellow citrus, darker at middorsal ( Fig. 6 ). Upper portion of eye intensely red. Infraorbital and opercular areas silvery. Some specimens with light orange coloration at the distal portions of dorsal and anal fins.

Sexual dimorphism. Sexually dimorphic characters of Hyphessobrycon citrus are related to fin length and shape. Pectoral and pelvic fins of males are slightly larger than in females. When adpressed, tip of pectoral fin reaches pelvic-fin origin in males, however, not in females. When adpressed, tip of pelvic fin of males may reach the base of anal fin or falls shortly, whereas not in females. Anal-fin base convex in males and roughly straight in females. Anal fin lobe with pointed profile in males due to elongated anteriormost branched anal-fin rays; smooth in females ( Figs. 6-7 ).

Geographical distribution. Endemic Known from the Serra do Cachimbo, in the headwaters of the rio Braço Norte, tributary of the rio Teles Pires, rio Tapajós basin, Pará State, Brazil ( Fig. 5 ).

Etymology. The specific epithet comes from the Latin “ citrus ”, referring to its bright yellow coloration similar to several citrus fruits. A noun in apposition.

Conservation status. Hyphessobrycon citrus is exclusive to the Serra do Cachimbo, in the headwaters of the rio Braço Norte, tributary of the rio Teles Pires, rio Tapajós basin. Despite a highly restricted distribution, the species inhabits a relatively well-preserved basin with no identifiable threats. Most of the basin where it occurs is located within protected areas (Reserva Biológica Nascentes da Serra do Cachimbo and FAB Military Zone). Therefore, Hyphessobrycon citrus should be classified as Least Concern (LC) following the International Union for Conservation of Nature (IUCN) categories and criteria (IUCN Standards and Petitions Subcommittee, 2022).

Figures

FIGURE 5 | Distribution map of Hyphessobrycon cachimbensis (pink); Hyphessobrycon n. sp. (yellow). Stars represent type-localities. The typelocality of Hyphessobrycon cachimbensis is the same as the FAB Airport - Campo de Provas Brigadeiro Velloso. Dashed line delineates the watershed boundary between the rio Tapajós and rio Xingu basins.

FIGURE 6 | Hyphessobrycon citrus, Brazil, Pará State, rio Tapajós basin, rio Teles Pires drainage, tributary of rio Braço Norte. A. MZUSP 128236, holotype, 38.0 mm SL, male; B. MZUSP 101429, paratype, 39.4 mm SL, female.

FIGURE 7 | Living specimens of Hyphessobrycon citrus, not measured, from Brazil, Pará, rio Tapajós basin, rio Teles Pires drainage. A. MZUSP 128237, male paratype, tributary of rio Braço Norte near BR- 163 road; B. MZUSP 96823, female paratype, tributary of rio Peixoto de Azevedo at bridge on BR-163 road.

FIGURE 8 | Lateral view of upper and lower jaws of Hyphessobrycon citrus, MZUSP 96847, paratype, 35.6 mm SL, coronomeckelian removed. Scale bar = 0.5 mm.