Tetragonopterus franciscoensis, 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 : 32-35

Tetragonopterus franciscoensis , new species

Fig. 12 , Table 6

Tetragonopterus chalceus (not Cuvier): Britski et al., 1988: 20, 44–45, 96 (list of species, Três Marias, São Francisco). Tetragonopterus aff. chalceus, Silva et al., 2013: 1613 –1631 (DNA barcoding).

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

Holotype. MZUSP 120566, 76.5 mm SL, Brazil, Minas Gerais, Três Marias, Rio São Francisco , 18°30’S 45°17’W, H. Britski & I. A. Dias , 14–18 Feb 1965.

Paratypes. All from Brazil . MZUSP 17081, 8 , 67.9–86.0 mm SL, collected with holotype. LBP 10294, 21, 70.7–91.3 mm SL, Minas Gerais, São Roque de Minas, Rio São Francisco , 20°11’03.4”S 45°50’57.9”W, J. Senhorini et al., 14 Apr 2010 . LBP 10319, 1, 52.7 mm SL, Minas Gerais, Pirapora, Rio São Francisco , 17°13’33.7”S 44°48’27.9”W, J. Senhorini et al., 12 Sep 2010 . LBP 10350, 13, 52.1–64.1 mm SL, Minas Gerais, Pirapora, Rio São Francisco , 17°19’29.9”S 44°45’57.2”W, J. Senhorini et al., 14 Jul 2010 . LBP 10394, 13, 58.5–80.4 mm SL, Minas Gerais, Buritizeiro, Rio São Francisco , 17°19’32.4”S 44°46’01.0”W, J. Senhorini et al., 15 Jul 2010 . LBP 11540, 2, 46.2–47.6 mm SL, Sergipe, Porto da Folha, Rio São Francisco , 10°01’11.1”S 37°07’04.6”W, J. Senhorini et al., 23 Nov 2010 . LBP 11552, 2, 45.4–49.2 mm SL, Bahia, Jenipatuba, Rio São Francisco , 9°55’28.4”S 37°07’22.5”W, J. Senhorini et al., 23 Nov 2010 . LBP 11571, 1, 30.3 mm SL, Bahia, Jenipatuba, Rio São Francisco , 9°56’03.5”S 37°06’53.8”W, J. Senhorini et al., 24 Nov 2010 . Non types: MZUSP 90886, 5 , 42.3–46.4 mm SL, Bahia, Iaçu, Rio Paraguaçu , 12°41’05”S 40°07’05”W, A. Zanata et al., 0 9 May 2006 . MZUSP 90905, 3 , 49.3–64.2 mm SL, Bahia, Queimadas, Rio Itapicuru , below Barragem Grande, 10°59’02”S 39°40’09”W, A. Zanata et al., 15 Jun 2005 .

Diagnosis. Tetragonopterus franciscoensis is distinguished from all other congeners, except T. anostomus , by the presence of 11–17 olfactory lamellae (vs. 20–41). Tetragonopterus franciscoensis also differs from T. anostomus and T. araguaiensis by having 11–14 gill rakers on lower limb (vs. 17–20). Tetragonopterus franciscoensis differs from T. kuluene and T. anostomus by having two conspicuous humeral marks (vs. only one conspicuous humeral mark). It differs from T. ommatus by the presence of 1–4 maxillary teeth (vs. 7–8) and by having a mark centered on the caudal peduncle (vs. mark limited to the posterior portion of the caudal peduncle).

Tetragonopterus franciscoensis differs from T. rarus by the absence of dark stripes on the flank (vs. presence of stripes); it differs from T. rarus and T. georgiae by having 3.5 scale rows between lateral line and pelvic-fin origin (vs. 4.5–5.5). Tetragonopterus franciscoensis further differs from T. argenteus by the presence of 7–9 predorsal scales (vs. 11–17). Tetragonopterus franciscoensis differs from T. denticulatus by having humeral marks separated by only one vertical scale row (vs. humeral marks separated by three vertical scale rows). Finally, T. franciscoensis differs from T. chalceus by having thinner and sharper principal teeth on dentary (vs. more robust teeth).

Description. Morphometric data summarized in Table 6. Body compressed and moderately elongate when compared with congeners. Greatest depth at origin of dorsal fin. 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 to dorsal-fin origin; slightly convex from end of 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; slightly convex along base of anal fin. Caudal peduncle with dorsal and ventral profiles nearly straight.

Holotype Range Mean Standard length (mm) 76.5 29.9–92.8 70.5 Percentages of standard length

Greatest depth 48.5 48.5–58.7 53.9 Predorsal length 51.0 49.6–57.1 52.5 Prepectoral length 28.1 27.4–35.2 29.3 Prepelvic length 48.3 46.9–53.4 50.4 Preanal length 65.4 62.3–76.0 68.4 Caudal peduncle depth 11.5 9.46–17.2 11.0 Caudal peduncle length 6.9 4.67–15.0 7.1 Pectoral-fin length 23.5 18.5–28.5 22.6 Pelvic-fin length 17.4 7.76–20.8 16.9 Dorsal-fin length 32.0 27.0–38.7 33.1 Length of dorsal-fin base 16.4 15.0–19.8 16.8 Anal-fin length 13.9 12.8–32.7 14.6 Length of anal-fin base 37.7 33.4–40.1 37.5 Distance from eye to dorsal-fin origin 48.3 41.9–49.9 48.3 Distance from dorsal-fin origin to caudal-fin base 56.3 50.7–57.9 54.8 Head length 27.5 25.6–29.6 27.7 Head depth 23.7 22.3–33.6 25.6 Percentages of head length

Snout length 14 12–19 14.3 Maxillary length 44 41–49 44.3 Horizontal orbital diameter 46 40–49 44.2 Least interorbital width 36 30–38 34.1 Snout shorter than orbital diameter. Mouth terminal. Upper and lower jaws of similar size. Premaxillary teeth in two rows of relatively robust teeth. Outer row with 5 (34)* or 6 (21) teeth with three cusps, central cusp longest. Inner row with 4 (1) or 5 (55)* teeth with three or five cusps, central cusp twice as long as the lateral cusps. Maxilla with 2 (9), 3 (35)* or 4 (15) tricuspid teeth. Dentary with 4 (55)* anteriormost teeth with four or five cusps followed by one (2 c&s) smaller tricuspid tooth and 12 (2 c&s) smaller conical or tricuspid teeth of similar size.

Dorsal fin rays ii,9 (55)*. 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,27 (2), v,28 (3), v,29 (16)*, v,30 (15), v,31 (14) or v,32 (4); 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 ray. Pelvic-fin rays i,7 (55)*. Pelvic-fin origin 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,11 (11), i,12 (26)*, or i,13 (17). Caudal fin forked, with i,17,i rays (2 c&s). Dorsal procurrent rays 11 and ventral procurrent rays 7 (2 c&s).

Scales large and cycloid. Lateral line complete and distinctly bent downward anteriorly. Longitudinal scales 29 (1), 30 (27), 31 (23) or 32 (4)*. Scale rows between lateral line and dorsal-fin origin 6 (18) or 7 (37)*; scale rows between lateral line and pelvic-fin origin 3.5 (55)*. Scale rows around caudal peduncle 12 (28), 13 (25)* or 14 (2). Anal-fin base covered by a single row of small scales, lobes of caudal fin scaled. Predorsal scales 7 (2), 8 (43) or 9 (10)*.

First gill arch with 9 (4)*, 10 (9) or 11 (8) rakers on the upper limb and 12 (4), 13 (9)* or 14 (8) rakers on the lower limb. Total vertebrae 30, precaudal vertebrae 12, intermediate vertebrae 2 and caudal vertebrae 16 (2 c&s). Supraneurals 3 (2 c&s).

Color in alcohol. General body color pale brown. Dorsal portions of head and body darkly pigmented. Dorsolateral portion of body scattered with few chromatophores along distal margins of scales; scales of ventrolateral portion of body less pigmented. Opercular and infraorbital bones silvery. Two conspicuous vertical dark humeral marks spaced by one or two scales, with anterior more evident. Anterior humeral mark extending over four horizontal scale rows above lateral line. Posterior humeral mark extending over three horizontal scales rows above lateral line. Caudal peduncle with a rounded or horizontally elongate dark mark. Midlateral silvery stripe broad, running from supracleithrum to anterior margin of the dark mark on caudal peduncle. Anal, pelvic, and dorsal fin hyaline, outlined by small chromatophores at distal portions of rays. Adipose fin hyaline with distal margins covered by small chromatophores ( Fig. 12 a).

Sexual dimorphism. None observed.

Distribution. Tetragonopterus franciscoensis occurs in the Rio São Francisco basin, Rio Paraguaçu and Rio Itapicuru, all coastal drainages of northeastern Brazil ( Fig. 2 a).

Etymology. The specific epithet franciscoensis is in reference to the Rio São Francisco, where the species is well known and abundant. An adjective. Tetragonopterus franciscoensis is popularly known as “piaba-rapadura” in the state of Minas Gerais.

Figures

FIGURE 12. Tetragonopterus franciscoensis. a) MZUSP 120566, holotype, 76.5 mm SL, Brazil, Minas Gerais, Três Marias, Rio São Francisco basin. b) Live specimen. Photo (b) by J. L. O. Birindelli.