Tetragonopterus kuluene, 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 : 35-38

Tetragonopterus kuluene , new species

Fig. 13 , Table 7

Tetragonopterus sp. Xingu: Melo et al., 2016:709 –717 (molecular phylogeny).

Holotype. MZUSP 120567, 44.3 mm SL, Brazil, Mato Grosso, Paranatinga, Rio Culuene, Rio Xingu basin, 13°49’00”S 53°15’00”W, J. Birindelli, L. Souza & A. Akama , 21 Aug 2006.

Paratypes. All from Brazil: MZUSP 91950, 60 , 52.6– 39.1 mm SL, collected with holotype . MZUSP 97134, 2 , 56.9–60.4 mm SL, Pará, Altamira, Xingu basin, Rio Curuá , 8°43’41”S 55°01’38”W, J. Birindelli, L. Souza, A. Netto-Ferreira, M. Sabaj Pérez & N. Lujan, 22 Oct 2007 . MZUSP 64370, 2 , 57.3–58.7 mm SL, Mato Grosso, Paranatinga, Xingu basin, Rio Culuene , F. Machado & R. Calegari, 6–7 Nov 1997 . MZUSP 91737, 3 , 55.9–62.6 mm SL, same data as holotype . MZUSP 97134, 2 , 56.9–60.4 mm SL, Pará, Altamira, Xingu basin, Rio Iriri ; J. Birindelli, L. Souza, A. Netto-Ferreira, M. Sabaj Perez & N. Lujan, 13 May 2007. LBP 15699, 5, 34.4–39.7 mm SL ; LBP 15711, 5, 41.9–63.9 mm SL, Mato Grosso, Ribeirão Cascalheira, Xingu basin, Rio Suiá-Missu , 13°09’13.6”S 51°55’18.7”W, C. Oliveira, M. Taylor, G. Silva & J. Henriques, 30 Sep 2012 . LBP 16731, 1, 45.2 mm SL, Pará, Altamira, Rio Xingu , 3°12’50.8”S 52°12’42”W, C. Oliveira & R. Britzke, 0 3 Oct 2012 . Non-types: All from Brazil: MZUSP 111807, 61.3 –67.7 mm SL, Altamira , Rio Xingu , Rio Iriri , near the Rio Xingu mouth, 03°49’40”S 52°41’31”W . MZUSP 107416 , 81.0 mm SL, Boa Esperança, Rio Xingu , 03°33’44”S 52°20’59”W.

Diagnosis. Tetragonopterus kuluene is distinguished from all congeners, except T. anostomus , by having only one conspicuous humeral mark (vs. two conspicuous humeral marks). Tetragonopterus kuluene differs from T. anostomus by having a terminal mouth (vs. subsuperior mouth); it differs from T. anostomus and T. araguaiensis by the number of gill rakers on the lower (12–13) and upper (8–9) limbs of the first gill arch (vs. 17–20 and 10–12).

Tetragonopterus kuluene differs from all congeners, except T. anostomus , T. denticulatus and T. juruena , by the presence of 5–6 principal dentary teeth (vs. 4) and by having thinner and sharper teeth (vs. more robust teeth). Tetragonopterus kuluene differs from T. denticulatus by having six scale rows between lateral line and dorsal-fin origin (vs. 7). In addition, T. kuluene differs from T. argenteus by having eight predorsal scales (vs. 11–17); it differs from T. carvalhoi by the presence of a rounded dark mark on the caudal peduncle (vs. a lozenge-shaped dark mark on the caudal peduncle). Tetragonopterus kuluene differs from T. rarus by the absence of dark longitudinal stripes on the trunk (vs. presence of stripes); it differs from T. georgiae and T. rarus by having 3.5 scale rows between lateral line and pelvic-fin origin (vs. 4.5–5.5). Finally, T. kuluene differs from T. ommatus by the presence of 2–5 maxillary teeth (vs. 8–7) and by having the mark centered on caudal peduncle (vs. mark limited to posterior portion of caudal peduncle).

Description. Morphometric data presented in Table 7. Body compressed and moderately elongate when compared with congeners. Greatest body depth at dorsal-fin origin. Dorsal profile slightly convex between tip of snout and vertical through middle of orbit; slightly concave from this point to end of occipital process and then convex from that point to dorsal-fin origin; straight or slightly convex along the dorsal-fin base to rear of adipose fin. Prepelvic region transversely flattened with distinct, longitudinally aligned lateral keels. Ventral profile slightly convex from lower lip to slightly behind vertical through pectoral-fin origin; convex from that point to anal-fin origin; straight along anal-fin base. Caudal peduncle with dorsal and ventral profiles slightly concave.

Holotype Range Mean Standard length (mm) 44.4 34.4–63.9 46.1 Percentages of standard length

Greatest depth 45.7 40.4–53.1 45.7 Predorsal length 50.9 48.0–53.4 51.3 Prepectoral length 30.0 27.9–32.3 30.3 Prepelvic length 48.4 46.6–53.8 49.9 Preanal length 65.3 62.5–71.8 65.8 Caudal peduncle depth 9.9 8.8–11.1 9.8 Caudal peduncle length 6.9 5.9–11.0 8.6 Pectoral-fin length 23.9 20.3–26.6 24.0 Pelvic-fin length 19.0 15.9–21.9 19.8 Dorsal-fin length 35.8 30.4–38.3 34.4 Length of dorsal-fin base 17.1 14.4–17.5 16.0 Anal-fin length 19.9 14.2–24.6 20.1 Length of anal-fin base 36.4 33.4–39.4 35.3 Distance from eye to dorsal-fin origin 48.2 45.2–49.9 47.9 Distance from dorsal-fin origin to caudal-fin base 53.3 49.6–58.4 54.4 Head length 29.8 22.4–26.7 24.4 Head depth 25.1 22.4–26.7 24.5 Percentages of head length

Snout length 12 12–18 14.1 Maxillary length 47 44–52 47.0 Horizontal orbital diameter 48 47–55 50.7 Least interorbital width 53 27–34 30.4 Snout shorter than orbital diameter. Mouth terminal. Premaxillary teeth in two rows of relatively small teeth. Outer row with 4 (2), 5 (13), 6 (39)*, 7 (14) or 8 (3) teeth with three cusps, central cusp slightly longer. Inner row with 5 (46) or 6 (30)* teeth with three or five cusps, central cusp twice as long as the lateral cusps. Maxilla with 2 (7), 3 (27)*, 4 (32) or 5 (9) teeth with three cusps. Dentary bearing 5 (64)* or 6 (7) anteriormost teeth with four or five cusps followed by one small tricuspid tooth and nine smaller conical teeth of similar size (4 c&s).

Dorsal-fin rays ii,9 (76)*. First unbranched ray shorter than second one. Dorsal-fin origin anterior to middle of body in SL. Distal margin of fin straight with anterior rays longer. Anal-fin rays v,26 (12), v,27 (22), v,28 (25)*, v,29 (11) or v,30 (2); posterior unbranched rays and anterior branched rays usually slightly longer than following ones. Anal-fin origin at vertical through base of ninth branched dorsal-fin rays. Pelvic-fin rays i,7 (77)*. Pelvic-fin origin located anterior to vertical line through dorsal-fin origin; distal margin of pelvic-fin angled, anterior rays longest. Tip of adpressed pelvic fin reaching anal-fin origin. Pectoral-fin rays i,12 (28), i,13 (37)*, or i,14 (10). Caudal fin forked, with i, 17, i rays (2 c&s). Dorsal procurrent rays 12–13 and ventral procurrent rays 10 (2 c&s).

Scales large and cycloid. Lateral line complete and distinctly bent downward anteriorly. Longitudinal scales 29 (4), 30 (16), 31 (21), 32 (13)* or 33 (2). Scale rows between lateral line and dorsal-fin origin 6 (76)*; scale rows between lateral line and pelvic-fin origin 3.5 (76)*. Scale rows around caudal peduncle 12 (7)*, 13 (33) or 14 (15). Predorsal scales 7 (13), 8 (49)* or 9 (1). Anal-fin base covered by a sheath of small scales. Lobes of caudal fin poorly scaled.

First gill arch with 8 (37) or 9 (12)* rakers on upper limb and 12 (41)*, 13 (17) or 14 (4) rakers on lower limb. Total vertebrae 30 or 31 (4 c&s). Precaudal vertebrae 13, intermediate vertebrae 2 and caudal vertebrae 15–16 (4 c&s). Supraneurals 3 (4 c&s).

Color in alcohol. General body colour pale brown. Dorsal portion of head and body darkly pigmented.

Dorsolateral portion of body scattered by few dark chromatophores along distal margins of scales. Ventrolateral portion of body generally unpigmented. Opercular and infraorbital bones silvery. One conspicuous vertical, dark humeral mark extending over four horizontal scale rows above lateral line. Caudal peduncle with a rounded dark mark. Midlateral silvery stripe broad, extending from supracleithrum to the caudal peduncle. Anal, pelvic and dorsal fins hyaline, with chromatophores concentrated in distal portions of rays. Adipose fin hyaline, distal portion scattered by few chromatophores ( Fig. 13 a).

Sexual dimorphism. Adult males with twelve bony hooks on the anteriormost ten branched rays of the anal fin, occurring in the first branched ray up to the tenth branched ray.

Distribution. Tetragonopterus kuluene is only known from the rio Xingu basin (Amazon basin, Brazil), where it occurs both at its upper portions, such as the Rio Culuene, Rio Suiá-Missu and Rio Curuá, as well as in the Volta Grande at the lower portion of the basin ( Fig. 2 a).

Etymology. The species name kuluene is after Rio Culuene (indigenous spelling), the type locality of the new species. A noun in apposition.

Figures

FIGURE 13. Tetragonopterus kuluene. a) MZUSP 120567, holotype, 44.4 mm SL, Brazil, Mato Grosso, Paranatinga, Rio Xingu, Amazon basin; b) Live specimen. Photo (b) by M. Taylor.