Rhinopetitia nigrofasciata, Menezes & Netto-Ferreira, 2019

Menezes, Naércio A. & Netto-Ferreira, Andre L., 2019, A systematic review of Rhinopetitia Géry (Teleostei, Characiformes, Characidae) with descriptions of four new species and redescription of R. myersi Géry, Zootaxa 4700 (1), pp. 59-86 : 76-80

Rhinopetitia nigrofasciata , new species

Figs. 18–21 , Table 4

Rhinopetitia cf. myersi, Not Géry, 1964 .— Netto-Ferreira et al., 2014 [in part MZUSP 111886; 111901. Comparative material used in the description of R. potamorhachia ].

Knodus hereresthes (not Eigenmann, 1908) – Thomaz et al., 2015 [in part, MNRJ 34678; multilocus phylogeny of the Stevardiinae ]

Holotype. MZUSP 124121 , female 33.0 mm SL: Brazil, Pará, Altamira, stream on the right bank of Rio Xingu below rapids of Naninduba , 03°06’49”S, 51°37’47”W, O. Oyakawa, J. Birindelli, C. Moreira, A. Akama, L. Sousa & H. Varella, 14 November 2011.

Paratypes. All from Brazil, Pará . MZUSP 111901 , 48 (29.0–35.0 mm SL) collected with holotype . INPA 59919 , 5 (27.0–31.5 mm SL) , MNRJ 51535 , 5 (30.0–32.0 mm SL) , MPEG 38603 , 5 (29.5–33.5 mm SL) , MZUSP 111886 , 60 (25.0–40.0 mm SL, 5 C&S 33.0–40.0 mm SL), UFRGS 27592 , 5 , (28.0–35.0 mm SL), Altamira, Pajé beach and mouth of stream Panela , Rio Xingu basin, 03°14’12”S, 52°13’21”W, O. Oyakawa, J. Birindelli, C. Moreira, A. Akama, L. Sousa & H. Varella, 14 November 2011 ; MZUSP 93241 , 2 (23.0–29.0 mm SL), Itaituba on the left bank of Rio Tapajós , 04°16’14”S, 55°58’34”W, L. M. Sousa & J. Birindelli, 07 November 2006 . MZUSP 23691 , 28 (17.0–25.0 mm SL), Barreirinha, Rio Tapajós , approximately 4°57’S, 57°01”W, Expedição Permanente à Amazônia, 23 November 1970 . MZUSP 93184 , 8 (16.0–31.0 mm SL), Itaituba, Rio Tapajós between Itaituba and rapids of Pimental , 04°21’34”S, 56°10’03”W, L.M. Sousa & J. Birindelli . MZUSP 93240 , 9 (SL 24.0–28.0 mm), Pimental, right bank of Rio Tapajós , 04°34’S, 56°15’39”W, L.M. Sousa & J.L. Birindelli, 11 November 2006 . MZUSP 25554 , 30 (22.0–35.0 mm SL), Pimental, right bank of Rio Tapajós upstream the headquarters of the Parque Nacional , 4°36’00”S, 56°16’00”W, J.C. Oliveira, 5 January 1979 .

Diagnosis. Rhinopetitia nigrofasciata differs from most congeners (except and R. oligolepis and R. potamorhachia ) by the lower body depth (19.1–24.8 % of SL, Fig. 4 , table 4; vs. 25.0–31.1% of SL, in R. myersi , R. paucirastra and R. melanohumeralis —tables 1, 2, and 5, respectively). The new species can be further distinguished from R. myersi by the presence of more lateral line scales and more circumpeduncular scales (35–39 and 13–14 vs. 32–34, and 12 respectively), from R. paucirastra by the higher number of gill rakers on the first branchial arch (13–19 vs. 8–12), and from R. melanohumeralis by the presence of a well-marked longitudinal stripe extending throughout the body, the inconspicuous humeral blotch and the lack of a reticulate pattern on the flanks (vs. longitudinal stripe diffuse, visible only posterior to dorsal-fin origin). The new species is distinguished from R. oligolepis by the presence of 5 longitudinal scale rows between dorsal-fin origin and lateral line (5 vs. 4), and from R. potamorhachia by the lower number of teeth cusps on both jaws (3–5 vs. 7–9).

Description. Morphometrics of holotype and paratypes in Table 4 . Body small (largest examined specimen 41.0 mm SL). Head and body elongate and laterally compressed; greatest body depth at dorsal-fin origin. Profile distinctly convex from upper jaw to posterior nostril, slightly convex from latter point to dorsal-fin origin, straight along dorsal-fin base, nearly straight to slightly concave from latter point to adipose-fin origin, and concave from latter point to anteriormost dorsal procurrent ray. Ventral body profile convex from tip of lower jaw to isthmus, nearly straight from that point to vertical through pectoral-fin origin, convex from latter point to pelvic-fin origin, and straight from that point to anal-fin origin. Ventral profile along anal-fin base straight and concave on caudal peduncle.

Mouth sub-terminal to nearly inferior; lower jaw short, included in upper jaw when mouth closed. Posterior tip of maxilla reaching slightly beyond vertical through anterior border of pupil. Outer premaxillary tooth row with 4 (8), 5 (88), 6 (110*), 7 (9) teeth, each with three (1), four (2), or 5 (3) cuspidate teeth, inner row with 4 (215) five (5) cuspidate teeth ( Fig. 19 ). Maxillary ( Fig. 19 ) with 1 (6), 2 (170*), 3 (34), or 4 (5) teeth, anterior larger teeth with five (3) or six (2) cusps, smaller posterior teeth with 3 cusps (5). Dentary ( Fig. 19 ) with 4 (215), anterior large five cuspidate teeth (5), followed by 2 (2) or 3 (3), smaller five cuspidate teeth, gradually decreasing in size posteriorly. First gill arch with external and internal rows of gill rakers; external row with, 13 (2), 14 (22), 15 (63), 16 (62*), 17 (42), 18 (12), or 19 (2) gill rakers. Branchiostegal rays 4 (5); 3 originating on anterior and 1 on posterior ceratohyal.

Scales cycloid. Lateral line complete; perforated scales 35 (23), 36 (70), 37 (95*), 38 (23), or 39 (1). Predorsal scales 11 (48), 12 (157*), or 13 (9). Scale rows between lateral line and dorsal-fin origin 5 (215); rows between lateral line and pelvic-fin origin 3 (56), or 4 (159*); circumpeduncular scales 13 (40), or 14 (170*). Single series of scales with sinuous posterior borders forming sheath along base extending to about 11 th anal-fin ray.

Pectoral-fin rays i,10 (6), 11 (94*), 12 (102), or 13 (6). Distal tip of longest pectoral-fin ray not reaching pelvic-fin origin. Pelvic-fin rays i,6,i (213), or i, 7, (2), tip of fin falling short of anal-fin origin. Supraneurals 4 (2), or 5 (3), rod shaped, or with discrete enlargement of dorsal portion; last supraneural located anterior to neural spines of 11 th (2) or 12 th (3) vertebral centra. Dorsal-fin rays ii,7,i, (215). First dorsal-fin pterygiophore inserting behind neural spine of 11 th centrum (5). Distal margin of extended dorsal fin straight to slightly convex. Dorsal-fin origin closer to caudal-fin base than to snout tip. Base of last dorsal-fin ray situated slightly anterior to vertical through anal-fin origin.Anal-fin rays iv–v, 14 (13), 15 (71), 16 (74), 17 (41), 18 (15*), posteriormost ray adnate.Anal fin with short, inconspicuous, anterior lobe including last unbranched ray plus first 5–6 branched rays. Distal margin of anal fin concave.

First anal-fin pterygiophore inserting behind haemal arch of centra 16 th (2) or 17 th (3). Adipose fin present. Principal caudal-fin rays 10/9, (215.) Dorsal and ventral procurrent rays 10 (1), 11 (1), or 12 (3), 10 (3) or 11 (2) respectively. Vertebrae 35 (2), or 36 (3).

Color in alcohol. Ground color pale to yellowish brown. Small dark chromatophores around mouth extends up from tip of snout and back toward top of head until tip of supraoccipital spine and laterally on upper portion of opercle. Few scattered dark chromatophores on fourth, fifth and sixth infraorbital bones. Small dark chromatophores all over upper part of body above lateral line and scattered and smaller below lateral line above anal-fin base, fewer on anterior lower part of body.

A conspicuous dark mid-lateral stripe in freshly preserved specimens sometimes obscured by guanine with a very conspicuous black line of chromatophores, inserted more deeply into musculature. Stripe crossing upper portion of faint dark vertically elongate humeral blotch occupying four longitudinal scale rows vertically becoming narrower downwards. Midlateral stripe becomes wider posteriorly extending to caudal-fin base All fins hyaline with scattered dark chromatophores on dorsal, caudal, and anal fins and very few on pectorals, and pelvic fins.

Sexual dimorphism. Anal fin of sexually mature males ( Fig. 20 ) with bilateral hooks on largest unbranched ray and first five branched rays. Pelvic fins of sexually mature males with hooks on all branched rays ( Fig. 21 ). No hooks on fins of mature females.

Etymology. The specific name nigrofasciata is from the Latin words “niger” meaning black, dark and “fascia” meaning band, is in reference to the dark midlateral stripe along the sides of the body of this species.

Distribution. This species is so far known from small streams tributaries of the rivers Tapajós and Xingu, Pará, Brazil ( Fig. 9 ).

Figures

FIGURE 4. Body depth as a function of standard length for the species of Rhinopetitia.

FIGURE 9. Map of northern South America showing collecting sites and type localities (star symbols) of the species of Rhinopetitia. Red, R. myersi; white, R. paucirastra; light blue, R. oligolepis; yellow, R. nigrofasciata; green, R. melanohumeralis. Some symbols may represent more than one locality.

FIGURE 18. Rhinopetitia nigrofasciata, new species, MZUSP 124121, holotype, female, 33.0 mm SL, Brazil, Altamira, PA, Rio Xingu basin.

FIGURE 19. Rhinopetitia nigrofasciata, MZUSP 111886, 34.0 mm SL C&S, jaws and dentition, lateral view, lateral side, anterior at left.

FIGURE 20. Rhinopetitia nigrofasciata, MZUSP 111886, 34.0 mm SL C&S, sexually mature male; anal-fin rays, lateral view, left side, showing anal-fin hooks.

FIGURE 21. Rhinopetitia nigrofasciata, MZUSP 111886, 34.0 mm SL C&S, sexually mature male; pelvic-fin rays, ventral view, left side, showing pelvic-fin hooks.