Tetragonopterus juruena, Silva, Gabriel S. C., Melo, Bruno F., Oliveira, Claudio & Benine, Ricardo C., 2016

Silva, Gabriel S. C., Melo, Bruno F., Oliveira, Claudio & Benine, Ricardo C., 2016, Revision of the South American genus Tetragonopterus Cuvier, 1816 (Teleostei: Characidae) with description of four new species, Zootaxa 4200 (1), pp. 1-46 : 40-43

Tetragonopterus juruena , new species

Fig. 15 , Table 9

Holotype. LIRP 14033, 75.5 mm SL, Brazil, Mato Grosso, Sapezal, Rio Juruena , upper Rio Tapajós , 12°50’59”S 58°55’36”W, R.J. Ilário et al., 2007–2010.

Paratypes. LIRP 8586, 9 (1 c&s), 55.8–76.0 mm SL, collected with holotype. MZUSP 62825, 2 , 57.2–62.2 mm SL, Brazil, Mato Grosso, Juruena , Rio Juruena , upper Rio Tapajós, 10°26’00”S 58°20’00”W, F. Machado et al. 25–26 Jul 1997. Non-types: All from Brazil: MZUSP 93700, 61.3 –65.2 mm SL, Rio Papagaio , Rio Juruena , 12°46’04”S 58°23’05”W . MZUSP 96610, 10 , 41.6–58.2 mm SL, Rio Peixoto de Azevedo, Rio Teles Pires , 10°13’14”S 54°58’02”W . MZUSP 96775, 31.6 –56.3 mm SL, Peixoto de Azevedo, tributary of Rio Peixoto de Azevedo, Rio Teles Pires , 10°17’14”S 54°50’57”W . MZUSP 98404, 1 , 55.1 mm SL, Paranaíta, Rio Teles Pires , 09°27’50”S 56°27’58”W.

Diagnosis. Tetragonopterus juruena is distinguished from all congeners, except T. ommatus and T. kuluene , by the presence of 4–6 maxillary teeth (vs. 1–4). Tetragonopterus juruena differs from T. ommatus by having the dark mark centered on caudal peduncle (vs. a vertically-oriented mark limited to posterior portion of peduncle). Tetragonopterus juruena differs from T. anostomus , T. denticulatus and T. kuluene by the presence of four principal teeth in dentary (vs. 5–6) and by having more robust teeth on the dentary (vs. thinner and sharper teeth). Tetragonopterus juruena differs from T. anostomus by having a terminal mouth (vs. subsuperior mouth); it differs from T. anostomus and T. kuluene by having two conspicuous humeral marks (vs. only one humeral mark); it differs from T. denticulatus by having 6 scale rows between lateral line and dorsal-fin origin (vs. 7). Tetragonopterus juruena differs from T. anostomus and T. araguaiensis by the number of gill rakers on the lower (10–12) and upper (7–8) limbs of the first gill arch (vs. 17–20 and 10–12). Tetragonopterus juruena is also distinguished from T. argenteus by having 8 predorsal scales (vs. 11–17). It differs from T. carvalhoi by having a rounded dark mark on the caudal peduncle (vs. lozenge-shaped dark mark on the caudal peduncle).

Tetragonopterus juruena differs from T. rarus by the absence of longitudinal dark stripes on the trunk (vs. presence of stripes). Finally, T. juruena differs from T. rarus and T. georgiae by the presence of 3.5 scale rows between lateral line and pelvic-fin origin (vs. 4.5–5.5).

Description. Morphometric data summarized in Table 9. Body compressed and moderately elongate when compared with congeners. Greatest body depth at dorsal-fin origin. Dorsal profile slightly convex from snout tip to vertical through middle of orbit; slightly concave from this point to end of occipital process and then convex to dorsal-fin origin. Straight along dorsal-fin base. Slightly convex from rear of dorsal-fin base to rear of adipose fin. Prepelvic region transversely flattened with distinct, longitudinally aligned lateral keels. Ventral profile convex from lower lip to pelvic-fin origin; straight from this point to anal-fin origin and straight along anal-fin base. Caudal peduncle with slightly concave dorsal and ventral profiles.

Holotype Range Mean Standard length (mm) 75.5 55.8–75.5 65.0 Percentages of standard length

Greatest depth 44.5 42.5–46.9 45.0 Predorsal length 49.4 49.4–52.6 50.7 Prepectoral length 27.8 27.8–31.8 30.2 Prepelvic length 48.2 48.2–52.0 50.4 Preanal length 64.1 64.1–70.4 66.9 Caudal peduncle depth 9.57 8.55–9.57 9.12 Caudal peduncle length 8.92 6.70–9.84 9.15 Pectoral-fin length 21.3 21.3–24.5 23.4 Pelvic-fin length 16.5 16.5–20.0 18.6 Dorsal-fin length 31.2 30.6–36.1 32.9 Length of dorsal-fin base 15.7 14.9–17.5 16.0 Anal-fin length 18.2 16.9–20.5 1.53 Length of anal-fin base 31.8 30.6–33.9 32.4 Distance from eye to dorsal-fin origin 45.8 45.8–49.6 47.7 Distance from dorsal-fin origin to caudal-fin base 51.0 51.0–53.8 52.6 Head length 27.6 27.6–30.9 29.9 Head depth 23.6 23.6–25.3 24.3 Percentages of head length

Snout length 14 11–15 13.5 Maxillary length 50 46–51 49.5 Horizontal orbital diameter 49 48–51 49.3 Least interorbital width 31 27–31 28.9 Snout shorter than orbital diameter. Mouth terminal. Upper and lower jaw of similar size. Premaxillary teeth in two rows of relatively small teeth. Outer row with 5 (5)*, 6 (7) or 7 (1) teeth with three cusps, central cusp slightly longer. Inner row with 5 (10)* or 6 (2) teeth with three or five cusps, central cusp twice as long as the lateral cusps. Maxilla with 4 (6), 5 (3)* or 6 (3) teeth with three cusps. Dentary with 5 (12)* anteriormost teeth with four or five cusps followed by nine (1 c&s) smaller teeth of similar size with two cusps.

Dorsal -in rays ii,9 (12)*. First unbranched ray shorter than second one. Dorsal-fin origin anterior to middle of body in SL. Distal margin of dorsal fin straight, anterior rays longer. Anal-fin rays v,24 (1), v,25 (2) v,26 (3) v,27 (4)* or v,28 (1); posterior unbranched rays and anterior branched rays slightly longer than following rays. Anal-fin origin at vertical through two scales posterior to last branched dorsal-fin ray. Pelvic-fin rays i,7 (12)*. Pelvic-fin origin located at vertical line through dorsal-fin origin. Distal margin of pelvic fin angled, anterior rays longest.

Pectoral-fin rays i,11 (3), i,12 (1), i,13 (5) or i,14 (3)*. Caudal fin forked, with i,17,i rays (1 c&s). Dorsal procurrent rays 12 and ventral procurrent rays 7 (1 c&s).

Scales large and cycloid. Lateral line complete and distinctly bent downward anteriorly. Longitudinal scales 29 (1), 30 (5), 31 (4) or 32 (1)*. Scale rows between lateral line and dorsal-fin origin 6 (12)*; scale rows between lateral line and pelvic-fin origin 3.5 (12)*. Scale rows around caudal peduncle 13 (12)*. Anal-fin base with a sheath of scales. Lobes of caudal fin poorly scaled.

First gill arch with 7 (3) or 8 (7)* rakers on upper limb and 10 (2), 11 (3) or 12 (4)* rakers on lower limb. Total vertebrae 31, precaudal vertebrae 13, intermediate vertebrae 2 and caudal vertebrae 16 (1 c&s). Supraneurals 3 (1 c&s).

Color in alcohol. General body color pale brown. Dorsal portions of head and body darkly pigmented. Opercular and infraorbital bones silvery, scattered by larger chromatophores. Dorsolateral and ventrolateral portion of body with few chromatophores along distal margins of scales. Two conspicuous, vertical, humeral marks separated by two scale rows, anterior mark more evident. Anterior mark extending over four horizontal scale rows above lateral line. Posterior humeral mark extending over three horizontal scale rows above lateral line. Caudal peduncle with a rounded or oval dark mark. Midlateral silvery stripe broad, extending from supracleithrum to anterior margin of dark mark on caudal peduncle. Anal, pelvic, and dorsal fins hyaline, with chromatophores concentrated in distal portions of rays. Adipose fin hyaline speckled by few chromatophores distally ( Fig. 15 a).

Sexual dimorphism. Adult males with bony hooks on distal segments of the first eight branched rays of the anal fin. Two bony hooks per segment.

Distribution. Tetragonopterus juruena is currently known from the Rio Juruena and Rio Teles Pires, major tributaries of the Rio Tapajós, Amazon basin ( Fig. 2 a).

Etymology. The name juruena is after the Rio Juruena , the type locality of the new species. A noun in apposition.

Figures

FIGURE 15. Tetragonopterus juruena. a) LIRP 14033, holotype, 75.5 mm SL, Brazil, Mato Grosso, Sapezal, Rio Juruena, Rio Tapajós, Amazon basin; b) LIRP 8586, paratype, same data as holotype, live specimen. Photo (b) by F. Dagosta.