Brycon costaricensis, Angulo, Arturo & Gracian-Negrete, Jatziry Marlene, 2013

Angulo, Arturo & Gracian-Negrete, Jatziry Marlene, 2013, A new species of Brycon (Characiformes: Characidae) from Nicaragua and Costa Rica, with a key to the lower Mesoamerican species of the genus, Zootaxa 3731 (2), pp. 255-266 : 258-263

Brycon costaricensis , new species

Table 1, Figure 2

Brycon guatemalensis (not Regan 1908): Meek, 1914: 108–109 ( Costa Rica, Atlantic slope, Limón: Río Costa Rica, Quebrada La Victoria, Río Zent and Río Parismina); Fowler, 1923: 23 ( Nicaragua, Atlantic slope: Río Eden and Río Tunky); Hildebrand, 1938: 275 (key), 281–282 (distribution, in part: “ranges on the Atlantic slope from Guatemala to Western Panama ”; Costa Rica and Nicaragua reference); Miller, 1966: 137 (distribution, in part: “Atlantic slope from the Río Grijalva, Tabasco and Chiapas, Mexico southward to eastern Panamá ”; Costa Rica and Nicaragua reference); Bussing, 1976: 158–161 (distribution, in part: Atlantic slope from Guatemala to Western Panama; Costa Rica and Nicaragua reference); Bussing & López, 1977: 16, 20, 24, 27 ( Costa Rica, Atlantic slope, Alajuela: Arenal Drainage); Géry, 1977: 339 (distribution, in part: “Central America ”; Costa Rica and Nicaragua reference); Bussing, 1985: 457 (distribution, in part: Atlantic slope from Guatemala to western Panama, with two discontinuities; Costa Rica and Nicaragua reference); Bussing, 1987: 75–76 (distribution, in part: Atlantic slope from Grijalva, Mexico to western Panama, with two discontinuities; Costa Rica and Nicaragua reference); Burcham, 1988: 277–283 ( Costa Rica, Atlantic slope, Heredia: La Selva Biological Station, Río Puerto Viejo: alimentation); Ulloa-Rojas et. al, 1989: 128–129 ( Costa Rica, Atlantic slope, Alajuela: Arenal Drainage); Bussing, 1993: 779 ( Costa Rica, Atlantic slope, Heredia: La Selva Biological Station, Río Puerto Viejo: ecology); Bussing, 1994: 196–198 ( Costa Rica, Atlantic slope, Heredia: La Selva Biological Station, Río Puerto Viejo: ecology); Horn, 1997: 259–263 ( Costa Rica, Atlantic slope, Heredia: La Selva Biological Station, Río Puerto Viejo: seed dispersion of Ficus glabatra ); Bussing, 1998: 92–96 (distribution, in part: Atlantic slope from Grijalva, Mexico to western Panama, with two discontinuities; Costa Rica and Nicaragua reference); Banack et al., 2002: 232, 237, 239–241 ( Costa Rica, Atlantic slope, Heredia: La Selva Biological Station, Río Puerto Viejo: seed dispersion of Ficus insipida ); Drewe et al., 2004: 890–899 ( Costa Rica, Atlantic slope, Heredia: La Selva Biological Station, Río Puerto Viejo: gut morphology, alimentation, digestive enzyme activity); Smith & Bermingham, 2005: 1839 (distribution, in part: “San Juan province”; Costa Rica and Nicaragua reference); Molina, 2006: 31–36 ( Costa Rica: larval development); Reeves & Bermingham, 2006: 88 (distribution, in part: from “ Costa Rica to Mexico ”; Costa Rica and Nicaragua reference); Herrera- Vásquez et al., 2007: 168 ( Costa Rica, Atlantic slope); Espinoza, 2008: 1975 ( Costa Rica, Atlantic slope, Alajuela: Caño Crucitas, Quebrada descubrimiento, Río Infiernillo, Quebrada Llano Verde and Quebrada Minas).

Holotype. UCR 2936-01: 128.1 mm SL, Costa Rica, Atlantic slope, Heredia, Sarapiquí drainage, La Virgen de Sarapiquí, Río Sarapiquí, at the Tirimbina Biological Reserve, 149 m, 10°24'56.84"N, 84°07'18.70"W, C.A. Garita, 25 May 2013.

Paratypes. 50 specimens (47.8–325.1 mm SL). Costa Rica: UCR 0214-09: 2, 105.0– 132.9 mm SL, Limón, Matina drainage, Quebrada Chocolate, 4.5 km SW of Moin, on road between Limón and Liverpool, 15 m, 9º59'04.99"N, 83º05'29.51"W, W.A. Bussing and S. Salas, 20 October 1967; UCR 0215-02: 3, 96.7–128.8 mm SL, Limón, Parismina drainage, Río Siquirres 4–5 km W of Siquirres on road between Moravia and Siquirres, 240 m, 10º05'15.00"N, 83º32'44.27"W, H. Nanne, 15 October 1967; UCR 0263-08: 1, 234.0 mm SL, Alajuela, San Carlos drainage, Quebrada Máquina, 4.2 km from Florencia de San Carlos on road between Ciudad Quesada and Muelle de San Carlos, 90 m, 10º23'44.99"N, 84º28'39.33"W, W.A. Bussing, 1 September 1968; UCR 0444-10: 4, 144.8– 170.0 mm SL, Limón, Parismina drainage, Quebrada Salsipuedes, 1.5 km E. of Ventiocho Millas on provisional road to Limón, 20 m, 10º05'19.99"N, 83º21'44.27"W, W.A. Bussing, M. Bussing and R. Nishimoto, 17 October 1970; UCR 0843-02: 5, 47.8–114.7 mm SL, Quebrada Santa Rita, from 1 km above to 1.5 km below bridge, 5 km SW Florencia, San Carlos drainage, Alajuela, Costa Rica, 200 m, 10º19' 24.99"N, 84º31'0.01"W, J. Prendas, W. González, W. López and M. Murillo, 22 February 1975; UCR 0929–01: 3, 130.6– 265.1 mm SL, Alajuela, Lago de Nicaragua drainage, Río Zapote 2.6 km S of Canalete, on Upala road, Lago de 85 m, 10º49'59.99"N, 85º02'09.83"W, W. Bussing, H. Camacho and W. Gonzáles, 17 December 1975; UCR 0948-03: 4, 64.2–99.8 mm SL, Guanacaste, San Carlos drainage, Quebrada Pérez 2.6 km E of Arenal, 522 m, 10º28'19.99"N, 84º49'44.27"W, W.A. Bussing, E. Bussing and W. González, 5 January 1976; UCR 1351-19: 1, 151.8 mm SL, Limón, Matina drainage, Río Cuba, on road to Limón, Costa Rica, 15 m, 10º01'20.00"N, 83º13'14.75"W, W.A. Bussing, 25 September 1981; UCR 1570-02: 1, 230.0 mm SL, Alajuela, Lago de Nicaragua drainage, source of small stream, 2 km S of Bijagua, 440 m, 10º43'09.99"N, 85º03'59.99"W, W.A. Bussing, Ich. Course, 17 March 1984; UCR 1671- 01: 3, 84.0– 153.2 mm SL, Guanacaste, San Juan drainage, Tributary of Río Bijagua, 10º44'25.00"N, 85º03'09.84"W, W.A. Bussing, Ich. Course, 4 May 1985; UCR 1809-09: 3, 96.2–148.1 mm SL, Limón, Tortuguero drainage, Parque Nacional Tortuguero, Río Agua Fría, 10º27'49.99"N, 83º33'59.99"W, K. Winemiller, 18 June 1985; UCR 1827-05: 1 (C&S), 73.0 mm SL, Limón, Parismina drainage, Quebrada Herediana, 6 km NW of Siquirres, on road to Guápiles, 10 m, 10º08'09.99"N, 83º33'29.51"W, W.A. Bussing, Ich. Course, 21 March 1986; UCR 2147-02: 1, 140.4 mm SL, Alajuela, Lago de Nicaragua drainage, Río Caño Negro, Parque Nacional Volcán Rincón de la Vieja, in the main stream, 310 m, 10º47'45.00"N, 84º57'19.68"W, S. Navarro, L. Villalba and J. Fraizer, 11 March 1989; UCR 2852-01: 1 (C&S), 75.9 mm SL, Limón, Parismina drainage, Río Pacuare, J. Picado, 13 July 2004. Nicaragua: UCR 0268-01: 3, 72.5–105.5 mm SL, Zelaya, Escondido drainage, Río La Concha (flowing into Río Mico), 18 km W of Ciudad Rama, 150 m, 12º10' 00.00"N, 84º28'39.33"W, J.D. Villa, 21 April 1968; UCR 0457-02: 7, 67.0– 185.5 mm SL, Chontales, Prinzapolka drainage, Río Yoaya 13.6 km E of Siuna at road, 300 m, 13º40'00.00"N, 84º21'44.27"W, W.A. Bussing and G. Campos, 14 April 1971; UCR 0461-10: 6, 55.9- 82.9 mm SL, Chontales, Escondido drainage, Río Muhán 17.4 km SE of Villa Somoza at Managua, Rama road, 100 m, 12º11'00.00", 86º15'05.04"W, W.A. Bussing, G. Campos and A. Zepeda, 17 April 1971; UCR 1086-01: 1, 325.1 mm SL, San Juan drainage, Quebrada Peor es Nada, R. Beatty, 27 April 1976.

Diagnosis. Brycon costaricensis differs from all other Central American Brycon species by possessing 49 to 54 scales in the lateral line (vs. 43 to 48 in B. argenteus , 55 to 61 in B. guatemalensis , and more than 64 in B. behreae , B. chagrensis and B. striatulus ) and a anal fin notably longer than head, with 33 to 37 total rays (vs. an anal fin about equal to length of head, with 24 to 28 total rays in B. argenteus , B. obscurus , and B. petrosus , the last two species with 48 to 55 and 53 to 58 scales in the lateral line, respectively). The following combination of characters also can separate the species herein described from B. guatemalensis : 5 or 6 rows of scales between lateral line and pectoral fin base (vs. 7 or 8); 9 to 11 (generally 10) rows of scales between lateral line and dorsal fin base (vs. 10 to 12, generally 11); 5 to 7 (generally 6) rows of scales between lateral line and anal fin base (vs. 7 to 9, generally 8); and a elongated and shallow caudal peduncle, whose length is 1.78 to 2.35 times its depth (vs. a short and deep caudal peduncle, whose length is 1.25 to 1.61 times its depth).

Description. Morphometric and meristic data are given in Table 1. Body moderately slender, robust and moderately high in specimens above 300.0 mm of SL; largest body height at dorsal-fin level; sloped dorsal profile; head large, slightly acute anteriorly and moderately deep posteriorly, head depth about 64.30 to 79.22% (71.73%) of body deep; eye large and snout relatively short and conical, eye diameter about 0.86 to 1.65 (1.27) times snout length; mouth terminal, heterognathous, premaxillary extending slightly ahead of dentary, leaving 2 rows of teeth exposed in advance of it; maxillary almost reaching the middle of the eye, maxillary length about 28.38 to 37.33% (32.22%) of head length; lower jaw shorter than upper, leaving 2 rows of teeth exposed in advance of it; premaxillary teeth large, laterally in 2 series, anteriorly more or less definitely in 3 series (the outer series with 8– 10 (9) teeth, the second series with 7–10 (9) teeth and the inner series with 2 largest teeth); maxillary with 9–15 (11) medium sized teeth; dentary with 7–9 (8) large anterior teeth, 7–12 (9) small posterior teeth and 1 tooth at the symphysis, forming the inner row; first gill arch with 13–15 (14) lower gill rakers, 13–15 (14) upper gill rakers and 1 at angle; scales cycloid; lateral line complete from supracleithrum to caudal-fin base and decurved anteriorly; dorsal-fin origin equidistant from snout and base of caudal-fin or scarcely behind of the middle of SL; pectoral-fin longer than pelvic-fin, its length about 1.22 to 1.51 (1.38) times the pelvic-fin length or 0.75 to 1.12 (0.94) times the distance between the pectoral-fin origin and the pelvic-fin origin; anal-fin base almost equal in length that maximum body depth, its length about 0.85 to 1.09 (1.00) times the body depth; caudal peduncle large and shallow, its length about 1.78 to 2.35 (1.98) times its depth; caudal-fin broadly forked.

Color in life. See Figure 2 A. Overall coloration silvery, some of the scales with blackish edges, forming vertical streaks; olive dark back and pearl white belly; pinkish, yellowish, olive or bronze color opercular bones (in adults); posterior edge of gill-opening blackish (in adults); paired fins transparent, light pink or reddish (in juveniles), rosy gray or dark (in adults); dorsal and adipose fins light pink, yellowish, reddish (in juveniles), rosy gray or dark (in adults); a more or less distinct blackish spot on the caudal peduncle; tail pale pink, yellowish, reddish (mostly in juveniles) or dark (mostly in adults); anal and caudal fins usually dark-edged.

Color in alcohol. See Figure 2 B. Dorso-lateral body surfaces silvery to coppery, dark olive to dark brown dorsally, becoming gradually clear ventrally; posterior edge of gill-opening blackish (in adults); longitudinal stripes, present in some specimens, extending all along the trunk; moderate to darkly pigmentation on paired fins; dorsal and anal fins pale with some dark pigmentation on interradial membranes and distal margins; adipose-fin usually pigmented at the basis; relatively faint, rounded dark area on caudal peduncle; caudal-fin usually dark-edged.

Distribution. Brycon costaricensis is known from Wawa basin in northern Nicaragua to Matina basin in southern Costa Rica, Atlantic slope ( Figure 3 ). In addition, since no other Brycon species has been recorded between Cangrejal, Aguán and Patuca basins in central Honduras and Coco and Ulám basins in northern Nicaragua (Bussing 1998, Matamoros et al. 2009), B. guatemalensis (sensu stricto) should now be considered as restricted from the Grijalva and Usumacinta basins in southern Mexico (Miller et al. 2006) to the Ulúa and Leán basins in northwestern Honduras, in the Atlantic slope, and to the Choluteca basin at the Honduran Pacific slope (Matamoros et al. 2009).

Etymology. The specific name, costaricensis , refers to the country of the type locality: Costa Rica, Atlantic slope, Heredia, Sarapiquí drainage, La Virgen de Sarapiquí, Río Sarapiquí.

Common names. Machaca, Sábalo, Sabalete, Machaca del Atlántico (Bussing 1998, Angulo in press). Ecological notes. The literature mentioning Brycon guatemalensis should eventually be revised regarding the origin of the material used (see Distribution). Brycon costaricensis inhabits some lakes in Nicaragua and Costa Rica, but it is also abundant in fast-flowing rivers and streams since it is a very strong swimmer (Bussing & López 1977, Bussing 1998). It is found at elevations between 0 and 600 m in lakes, rivers and creeks (Bussing 1998). It tolerates temperatures between 21 and 34 °C (Bussing 1998).

Young specimens (less than 80 mm of total length) fed principally on insects while the largest ones (more than 80 mm of total length) consumed a large proportion of allochthonous vegetal matter, principally leaves (Burcham 1988). Horn (1997) and Banack et al. (2002) found that the largest individuals of this species can potentially disperse Ficus spp. ( Moraceae ) seeds for long distances along watercourses. Drewe et al. (2004) found that largest individuals of B. costaricensis have relatively larger intestines than juveniles specimens, and an ontogenetical change of main gut enzymes, associated with the ontogenetic change in diet (from carnivores to mainly herbivores). In addition, as in the case of B. opalinus (Cuvier 1819) , B. costaricensis possesses a large gall bladder, suggesting the importance of the digestion of lipids in these species (Drewe et al. 2004, Gomiero et al. 2008). Burcham (1988) also found that largest individuals of B. costaricensis are present in forest streams and usually absent from deforested areas that indicates that the removal of fruit trees from the banks of small streams leads to their local elimination or to a considerable decrease in their abundance.

Regarding the reproductive biology of B. costaricensis , little is known. Bussing (1998) mentions that pairs of this species lay eggs in an excavated nest in the sand substratum of creeks. Additionally, Molina (2006) describes their most relevant larval development characteristics after artificial fertilization of eggs of wild fish.

Brycon costaricensis is a delight for sport fisherman because of its fighting nature and the flesh is highly regarded (Bussing 1998). The latter author reported for this species a maximun size of 500 mm and a maximun weight of 4300 g.

Remarks. CVA recovered two distinct shape groups along both Canonical Variates (CV) ( Figure 4 ). Brycon guatemalensis and B. costaricensis specimens were evenly distributed among the two groups in CV1, meanwhile B. costaricensis and B. behreae were likewise distributed among the two groups in CV2. Both canonical variate axis are significant at the p <.001 level based on the Wilk’s lamda value (the sum of squares within groups divided by the total sum of squares within and between groups). The CV1 explained 74.82% of the shape variance.

An assignment test performed in CVAgen based on CV1 determined that all specimens had been correctly assigned to the respective group. Shape differences associated with the CV1 and CV2 are shown in Figure 4 . Brycon costaricensis , with positive scores on CV1 ( Figure 4 C) and negative scores on CV2 ( Figure 4 D), has slender bodies and caudal peduncles larger and shallower than specimens with negative scores on CV1 ( Figure 4 B) as well as deeper heads, eyes displaced dorsally, anterior fins insertion displaced anteriorly and the posterior end of the supraocipital spine positioned anteriorly and dorsally than specimens with positive scores on CV2 ( Figure 4 E).

Figures

FIGURE 2. (A) Holotype (128.1 mm SL) of Brycon costaricensis depicting live coloration (photo by Atsunobu Murase) and (B) preserved paratype (UCR 0 457, 98.5 mm SL).

FIGURE 3. (A) Map of lower Central America, showing known distribution of Brycon costaricenses (light area); (B, C) typelocality (D, E) indicated by the star, circles represent remaining localities.

FIGURE 4. A. Scatter plot of the first two axis of the CVA of the body shape for three Central American Brycon species (circles = B. guatemalensis, squares = B. behreae, equis = B. costaricensis). Deformation grids indicate extreme shape along CV axes (B = CV 1 -, C = CV 1 +, D = CV 2 -, E = CV 2 +).