Moenkhausia goya Deprá & Azevedo-Santos & Júnior & Dagosta & Marinho & Benine 2018, new species

Moenkhausia goya, new species

(Figs. 1–4)

Holotype. MCP 51734, 60.5 mm SL, Brazil, Goiás, Pirenópolis, ribeirão Dois Irmãos, trib. rio das Almas, rio Maranhão basin, 15°42'50"S 49°2'39"W, elevation 713 m, O. Vitorino, 20 Feb 2017.

Paratypes. All from Brazil, upper rio Tocantins basin. Goiás. LBP 23678, 2, 42.0– 44.4 mm SL; LBP 23679, 3, 39.4–47.8 mm SL Pirenópolis, ribeirão das Araras, trib. rio do Peixe, rio Maranhão basin, 15°42'15"S 49°2'12"W, elevation 722 m, O. Vitorino & G. C. Deprá, 12 Dec 2016. NUP 19099, 3, 35.1 – 41.8 mm SL, same locality and collector as LBP 23678, 20 Feb 2017. NUP 19100, 2, 56.2 – 61.9 mm SL, collected with holotype. LBP 23680, 2 c&s, 42.2–51.8 mm SL; NUP 19104, 17, 39.1 –63.0 mm SL, same locality and collector as holotype, 23 Apr 2017. MCNIP 1827, 2, 33.1 – 49.3 mm SL, Pirenópolis, córrego Limoeiro, trib. ribeirão Dois Irmãos, rio Maranhão basin, 15°43'47"S 49°2'28"W, elevation 737 m, O. Vitorino & G. C. Deprá, 15 Aug 2016. MCP 44632, 3, 48.9 – 59.6 mm SL, Itapaci, rio São Patricinho, trib. rio das Almas, rio Maranhão basin, 14°56'44"S 49°32'49"W, F. L. Garro, 16 Aug 2008. MNRJ 12655, 1, 61.0 mm SL, Niquelândia, rio do Peixe, rio Maranhão basin, G. W. Nunan & D. F. Moraes Júnior, 8 Oct 1985. MNRJ 12665, 19, 17.3 – 44.8 mm SL, Niquelândia, rio do Peixe, rio Maranhão basin, G. W. Nunan & D. F. Moraes Jr., 8 Oct 1985. MNRJ 12692, 98, 22.6 – 58.6 mm SL, Niquelândia, córrego Barriguda, trib. rio Bagagem, rio Maranhão basin, G. W. Nunan & D. F. Moraes Jr., 15 Oct 1985. MZUSP 53970, 18, 32.5 – 61.9 mm SL, Niquelândia, córrego Piqui, trib. rio do Peixe, rio Maranhão basin, 14°17'0"S 48°55'0" W, M. T. Rodrigues et al., May 1996. NUP 9273, 4, 56.0–61.0 mm SL, Goiás, córrego Brumado, trib. rio Uru, trib. rio das Almas, rio Maranhão basin, 15°48'51"S 49°50'36"W, elevation 658 m, D. S. Mendonça, 15 Feb 2009. NUP 19102, 4, 46.5 – 55.9 mm SL, Pirenópolis, ribeirão Dois Irmãos, rio Maranhão basin, 15°42'50"S 49°2'54"W, elevation 703 m, O. Vitorino, 23 Apr 2017. NUP 19192, 1, 50.6 mm SL, Planaltina, rio Arraial Velho, rio Maranhão basin, 15°4'31"S 47°55'43"W, elevation 672 m, T. Debona, Aug 2016. ZUEC 6414, 3, 52.6 – 60.6 mm SL, Niquelândia, rio Traíras, rio Maranhão basin, 14°36'32"S 48°28'44"W, T. C. Pessali & G. E. da Silva, 25–28 May 2011. MNRJ 13075, 52, 26.6 – 56.2 mm SL, Minaçu, unnamed tributary of córrego Lageado, trib. rio Tocantins, 13°38'S 48°19'W, D. F. Moraes Júnior, 16 Jan 1988. MNRJ 13167, 1, 42 mm SL, Minaçu, 1, 42 mm SL, unnamed stream between córrego do Ginho and córrego Mutum, trib. rio Tocantins, D. F. Moraes Jr., 27 Dec 1987. MZUSP 113978, 37 21.7–57.3 mm SL, 2 mol, Colinas do Sul, ribeirão São Joaquim, trib. rio Preto, 14°13'6.2"S 47°55'28.7"W, O. Oyakawa, A. Zanata, P. Camelier & M. Melo, 29 Nov 2012. MZUSP 114355, 2, 16.2 – 23.7 mm SL, Colinas do Sul, rio Preto, trib. rio Tocantins, 13°59'40"S 47°55'43.1"W, O. Oyakawa, A. Zanata, P. Camelier & M. Melo, 29 Nov 2012. MZUSP 40705, 117, 22.4 – 51.2 mm SL, Monte Alegre de Goiás, rio Bezerra, rio Paranã basin, 13°15´0"S 46°43'48"W, J. C. Oliveira & W. J. M. Costa, 22 Sep 1988. Tocantins. MZUSP 113843, 119, 22.0– 56.6 mm SL, Arraias, rio Bezerra, trio Paranã basin, 13°1'1"S 46°49'43.5"W, F. Dagosta, J. L. Birindelli, M. Loeb & Santos, 1 Dec 2012.

Diagnosis. Moenkhausia goya, new species, can be distinguished from most congeners, except M. britskii, M. conspicua Soares & Bührnheim, M. grandisquamis, M. orteguasae Fowler, M. rubra Pastana & Dagosta, M. venerei Petrolli, Azevedo-Santos & Benine and M. xinguensis, by the presence of a single round, relatively large humeral blotch. It can be readily distinguished from M. rubra by the absence of distinct dark pigmentation in the anteriormost anal-fin rays (vs. unbranched and first to fifth anteriormost branched anal-fin rays dark, especially distally), from M. conspicua and M. venerei by the absence of a black line along anal-fin base (vs. presence) and from M. orteguasae by the caudal fin hyaline or covered with scattered melanophores, but without distinct patches of dark pigmentation (vs. tip of caudal-fin lobes dark). It can be distinguished from M. britskii, M. grandisquamis and M. xinguensis, the most similar species, as well as from most other congeners, by having a dense pigmentation in the anal and dorsal fins, consisting of melanophores uniformly distributed over the interradial membranes throughout the fins (vs. fins hyaline). Additionally, Moenkhausia goya is distinguished from M. britskii and M. grandisquamis by having straight radii on the flank scales (vs. bent radii; see Azevedo-Santos & Benine, 2016, Fig. 2) and from M. xinguensis by having a larger humeral blotch, almost as broad as the eye (vs. about half as broad as the eye) and a thinner longitudinal dark stripe on body with fading edges, usually not retaining guanine when preserved (vs. longitudinal dark stripe wider, with sharp edges, frequently retaining guanine when preserved).

Description. Morphometric data in Table 1. Greatest body depth at dorsal-fin origin. Dorsal profile slightly convex from tip of snout to interorbital region, straight to slightly concave along interorbital region, convex to dorsal-fin base, straight along dorsal-fin base, slightly convex to adipose fin, and concave along caudal peduncle. Ventral profile markedly convex from tip of dentary to anal-fin base, roughly straight along anal-fin base, and concave along caudal peduncle.

Pre-pelvic region somewhat flattened, mainly at pelvic-fin insertion. Head and trunk compressed, somewhat ovoid in cross-section, broader dorsally. Greatest width just posterior to supracleithrum. Dorsal fin at middle of standard length, its base about half distance between end of dorsal fin and adipose fin. Adipose fin slightly anterior to end of anal fin base. First unbranched anal-fin ray at vertical through last dorsal-fin ray. Tip of pectoral fin falling short of pelvic-fin base. Tip of pelvic fin falling short of anal-fin base. Pelvic-fin insertion slightly anterior to vertical through first dorsal-fin ray, close to ventral profile of body. Head somewhat deeper than long. Nostril approximately at horizontal through dorsal margin of pupil. Orbit mostly in anterior half of head length and dorsal half of head depth. Infraorbital 3 contacting preopercle ventrally and posteriorly or falling short from it. Dorsal end of branchial opening slightly ventral to horizontal through dorsal margin of orbit.

Mouth terminal, isognathous. Posterior tip of maxilla at vertical through anterior margin of pupil and middle of infraorbital 2. Premaxillary teeth arranged in two rows; outer row with 4*(15), 5(19) tricuspidate teeth with central cusp larger; inner row with 4(2), 5*(32) pentacuspidate teeth with central cusp larger (Fig. 4). Maxilla with 1(6), 2*(43), 3(4) pentacuspidate teeth. Dentary with 4*(52), 5(1) large, tetracuspidate teeth with central cusp larger, followed by eight small, uni- to tricuspidate teeth decreasing in size posteriorly.

Dorsal-fin rays ii, 8(3), 9*(49), 10(1). Anal-fin rays iii(1), iv(1), 21(1), 22(3), 23(39), 24(13), 25(7), 26(1). Pectoral-fin rays i, 9(8),10(13), 11*(16), or 12(15). Pelvic-fin rays, i, 7*(34). Adipose fin present.

Scales cycloid. About 2–10 straight radii in each scale. Lateral line slightly curved, complete, with 31(4), 32(15), 33*(11), 34(15), or 35(1) pored scales. Transversal scales above lateral line 5*(52), 6(1); below lateral line, 4(46), 5*(7). Pre-dorsal scales 8(7), 9*(22), 10(1). Circumpeduncular scales 14*(37). A single scale row covering base of first unbranched to 13 th –23 rd branched anal-fin rays. Small scales covering the proximal two thirds of caudal-fin lobes.

Total vertebrae 33(2). Upper-branch gill rakers 5(1), 6(9), 7(18) or 8(4), lower-branch 8(1), 9(6), 10(18) or 11(7).

Color in alcohol. Background yellowish to tan. Dorsal surface of head dark brown, including upper jaw. Tip of lower jaw dark brown. Poorly preserved paratypes (NUP 9273) with infraorbital series and opercular bones retaining guanine. Melanophores scattered on infraorbital bones, close to ventral margin of eye. Melanophores all over opercle, mainly on its dorsal half. Body darker dorsally than ventrally. Melanophores on body scales forming reticulate pattern, especially on dorsal half; abdominal region lacking melanophore patterning. Reticulate pattern formed by melanophores distributed along margin of scales, especially on posterior margin. Reticulate pattern much less conspicuous in smaller specimens. Concentration of melanophores higher dorsally to anal-fin base than over ribs. Melanophores occasionally outlining myosepta dorsally to anal-fin base. Humeral blotch large, rounded, immediately dorsal to second to fourth lateral-line scales, covering about two or two and a half scale rows vertically. Dark-brown lateral band, its anterior end connecting with posterodorsal margin of humeral spot, and its posterior end on bases of median caudal-fin rays. Anterior end of lateral band narrow, occasionally diffuse. Lateral band broader and more conspicuous towards caudal peduncle, about one-scale deep at vertical through base of first dorsal-fin ray, one and a half-scale deep between vertical through last dorsal-fin ray and vertical through adipose fin, one scale deep ventrally to adipose fin and broadening to form three-scale deep lozenge-shaped mark on distal half of caudal peduncle. Lateral band located two scale rows dorsally to lateral line on anterior portion of body, one scale row on middle portions, and immediately dorsal to lateral line at posterior portion. Melanophores on lateral band more concentrated along horizontal myoseptum. Humeral blotch distinctly larger in adults. Lateral band broader and more conspicuous in adults. Poorly preserved non-type specimens (NUP 9273) with lateral band retaining guanine. Pectoral and pelvic fins hyaline. Dorsal, caudal and anal fins with hyaline rays and interradial membranes densely covered with melanophores. High concentration of melanophores mainly on basal portions of anal fin, except at distal portion of first anal-fin rays. Young specimens with vertical fins less dark than in adults.

Color in life. Similar to color in alcohol except in the following details (Figs. 2, 3): Head yellowish dark brown dorsally, silver laterally and ventrally. Abdominal region silvery. Dorsal portion of eye tan. Longitudinal stripe yellowish silver. Dorsal portion of body olive to plumbeous. Fins with light yellowish to reddish background, mainly the basal two-thirds of caudal fin. Distal portion of anal-fin anteriormost rays white.

Etymology. Moenkhausia goya is named after the Goyá, a South American ethnic group that lived in the central region of Brazil, which resisted to the encroachment of their territories until the 19 th century. They also originated the name of the state of Goiás, where most of the distribution of the new species lies.

Geographic distribution. Moenkhausia goya is known from the upper rio Tocantins basin (sensu Ribeiro et al., 1995), at the rio Maranhão and rio Paranã basins and in streams draining directly into the rio Tocantins upstream of its meeting with the rio Paranã (Fig. 5), states of Goiás and Tocantins, Brazil.

Conservation status. Moenkhausia goya is so far known from the upper rio Tocantins basin, where it is widely distributed. Despite existing some riparian forest degradation for pasture in several sites where the species occurs, it seems not to preclude its presence. Therefore, M. goya would be classified as Least Concern (LC) following the International Union for Conservation of Nature (IUCN) categories and criteria (IUCN Standards and Petitions Subcommittee, 2017).

Habitat and ecological notes. Moenkhausia goya occurs in lotic environments, generally shallow streams, shaded by riparian vegetation. It is also noteworthy that there seems to be a shift of habitat use by the species related to hydrological variability in creeks and riffles where it occurs. During the drier seasons, M. goya is more common in riffles, while during the rainy season it prefers the pool habitats where the water flow is less intense. Specimens with more vivid color in life were more often observed during the dry season, probably related to increase in the sexual activity of the species during this period.