Gephyrocharax caucanus Eigenmann, 1912

Vanegas-Ríos, James A., 2016, Taxonomic review of the Neotropical genus Gephyrocharax Eigenmann, 1912 (Characiformes, Characidae, Stevardiinae), Zootaxa 4100 (1) : 16-22

Gephyrocharax caucanus Eigenmann, 1912

( Figs. 7–9 )

Gephyrocharax caucanus Eigenmann, 1912: 24 [original description, holotype FMNH 56012 [CM 4802], type locality: “Cartago” (= Colombia: Valle del Cauca, upper Cauca River basin, Cartago)]. Eigenmann, 1914: 41 [listed, key]. Eigenmann, 1920c: 32 [listed from Magdalena River basin]. Eigenmann, 1922: 155 [catalogue]. Myers in Eigenmann & Myers, 1929: 477, 481–482, pl. 63, fig. 2, pl. 88, figs. 4–5 [key, redescription]. Schultz, 1944: 323 [key]. Miles, 1947: 156, fig. 107 [listed from Magdalena River basin, key]. Dahl, 1971: 134 [key]. Géry 1977: 351 –352, unnumbered fig. on page 352 [color in life]. Miles, 1973: 52 –53, fig. 31 [taxonomic comments]. Mojica, 1999: 557 [listed from Colombia, data compilation]. Maldonado-Ocampo, Ortega-Lara, Usma, Galvis, Villa-Navarro, Vásquez, Prada-Pedreros & Ardila, 2005: 89, fig. 92 [recorded for Andean drainages from Colombia, morphological and ecological data]. Ortega-Lara, Usma, Bonilla & Santos, 2006: 47 [listed from upper Cauca River basin]. Maldonado-Ocampo, Vari & Usma, 2008: 180 [listed from Colombia]. Arai, 2011: 82: [karyotype: 2n = 52]. Álvarez-León, Orozco-Rey, Páramo-Fonseca & Restrepo- Santamaría, 2013: 101 [listed from Colombia]. Bonilla-Rivero & López-Rojas, 2013: 489, fig. 1 [distribution map]. Vanegas-Ríos, Azpelicueta, Mirande & Gonzales, 2013: 282 [examined material]. Thomaz, Arcila, Ortí & Malabarba, 2015: Add. File 5 [tentative classification].

Diagnosis. Gephyrocharax caucanus differs from most congeners by the presence of an intense dark pigmentation (often red in live specimens) around the pelvic-fin origin in adult males (vs. pelvic-fin origin of adult males not pigmented or only with scattered chromatophores, except in G. sinuensis and G. valencia ) and by the absence of humeral blotch (vs. presence of this blotch, except in G. chocoensis , G. m a r t a e, and G. v a l e n ci a). Gephyrocharax caucanus is distinguished from G. sinuensis and G. valencia by the pigmentation pattern around the pelvic-fin origin, which is more concentrated on the lateral and ventral regions from the anal-fin origin across the pelvic area to the vertical crossing the midlength of pectoral fin (vs. this pigmentation more concentrated ventrally and anteriorly, especially around the pelvic-fin origin). Gephyrocharax caucanus also differs from G. sinuensis by the number of branched anal-fin rays (29–36 vs. 22–28), the pelvic-fin length of males (12.2–16.1 % SL vs. 17.1–26.8 % SL), the anal-fin length of males (13.2–17.8 % SL vs. 17.6–22.4 % SL), and the position of the anterior tip of pelvic bone (situated posterior to the 6th pleural rib vs. situated anterior to this rib). Additionally, the possession of a terminal lateral-line tube between caudal-fin rays 10 and 11 (vs. absence of this tube) differentiates G. caucanus from G. melanocheir , G. t o r res i, and G. valencia . The species is further distinguished from G. torresi and G. valencia by having a rhinosphenoid bone (vs. absence of this bone) and from G. chocoensis , G. intermedius , G. martae , G. melanocheir , G. t o r re s i, and G. venezuelae by the least interorbital width (27.1–33.7 % HL vs. 34.0–43.7 % HL). Gephyrocharax caucanus differs from G. m a r t a e by the number of branched anal-fin rays (29–36 vs. 28), number of lateral-line scales (42–47 vs. 40), snout to pectoral-fin origin length (22.8–27.9 % SL vs. 20.7 % SL), dorsal-fin base length (7.3–9.9 % SL vs. 12.8 % SL), anal-fin length (13.2–19.2 % SL vs. 61.6 % SL), and upper jaw length (37.5–42.8 % HL vs. 46.2 % HL). From G. intermedius it is also distinguished by the lesser body depth at dorsal-fin origin (20.5–28.3 % SL vs. 28.4–38.0 % SL) and number of vertebrae (41–42 vs. 37–39).

Description. Morphometric data in Table 2. Largest male 44.8 mm SL, largest female 50.2 mm SL. Body laterally compressed, with maximum depth at vertical through anal-fin origin or slightly anterior to this point. Dorsal profile of head straight from margin of upper lip to tip of supraoccipital spine. Dorsal profile of body straight or slightly convex from that point to dorsal-fin origin, slanting posteroventrally along dorsal-fin base, straight from posteriormost dorsal-fin ray to caudal peduncle ( Fig. 7 ). Ventral profile of body convex from tip of dentary to pelvic-fin origin, straight or slightly convex from this point to anal-fin origin, slanting posterodorsally and straight (or sometimes slightly curved) from this point to caudal peduncle origin. Anterior fontanel usually absent or reduced to narrow opening anterior to epiphyseal bar (in two adult specimens opening slightly larger with frontals contacting anteriorly). Anterior nostril rounded, separated by skin fold from larger posterior nostril. Groove with at least three rows of neuromasts extending from half-length between posterior pore of nasal bone and nostrils to posterior portion of frontals. Small groove with few neuromasts between nostrils and nasal bones.

Mouth superior, lower jaw projecting anterior to tip of upper jaw. Premaxilla with two rows of teeth. Outer row with 2 (3), 3* (50), or 4 (6) teeth; usually tricuspid, rarely bicuspid. Inner row with 4* (58) or 5 (4) teeth; symphyseal tooth tri- or tetracuspid, remaining teeth tri- to pentacuspid (sometimes posteriormost tooth conical). Maxilla sometimes toothless* (5), usually with 1 (53) or 2 (1) teeth; conical, bi- or tricuspid in all specimens ( Fig. 8 A). Maxilla posteriorly reaching vertical through anterior one-third of eye. Dentary with 8 (1), 9 (1), 10 (18), 11 (8), 12 (3), 13 (6), or 14 (1) teeth; three anteriormost teeth large, pentacuspid, followed by one median-sized tooth usually tricuspid (rarely tetracuspid), and 4 (1), 5 (1), 6 (18), 7 (8), 8 (3), 9 (6), or 10 (1) smaller conical, rarely bi- or tricuspid teeth ( Fig. 8 B).

Dorsal-fin rays ii,7 (1) or 8* (59). Nine* proximal pterygiophores on dorsal fin (6 rad, 4 c&s). Dorsal-fin origin located at vertical between anal-fin rays 9–14. Adipose-fin origin located at vertical through base of two or three posteriormost anal-fin rays. Anal-fin rays iii (1), iv* (33), v (26), or vi (1), 29 (1), 30 (4), 31 (10), 32 (13), 33 (16), 34* (12), 35 (4), or 36 (1) ( Fig. 6 ). Thirty-two to 35* proximal pterygiophores on anal fin (6 rad, 4 c&s). Anal-fin origin closer to origin of hypural joint than to snout tip. Pectoral-fin rays i,8 (7), 9 (45), or 10* (7). Pectoral-fin distal tip posteriorly reaching one-quarter to one-half of pelvic-fin length. Pelvic-fin rays i, 6 in all specimens (one atypical specimen with i,9). Pelvic-fin origin located at vertical between pored lateral-line scales 9–10 and slightly anterior to body midlength. Caudal fin forked with 10/9 principal rays in all specimens.

Scales cycloid, with variable number of radii along posterior margin. Lateral line complete, pored scales 42 (7), 43* (28), 44 (15), 45 (8), 46 (2), or 47 (1). Terminal lateral-line tube present. Predorsal scales 20 (5), 21* (19), 22 (29), or 23 (8). Scale rows between dorsal fin and lateral line 4 (1), 5* (49), or 6 (9). Scale rows between lateral line and anal fin 4 (6), 5* (52), or 6 (1). Scale rows between lateral line and pelvic fin 3 (1), 4* (52), or 5 (6). Circumpeduncular scales 12 (3), 13 (24), 14* (22), or 15 (1). Two rows of scales forming sheath along anal-fin base (rarely one row); main ventral row with 8 (1), 14 (1), 15 (3), 16 (2), 17 (12), 18 (7), 19 (3), 20 (4), or 21 (2) scales. Total number of vertebrae 41 (3) or 42* (7); 16* (10) precaudal and 25 (3) or 26* (7) caudal (6 rad, 4 c&s). Gill-rakers on dorsal limb of first branchial arch 6 (14) or 7* (35); ventral limb with 12 (15), 13 (27), 14* (6), or 15 (1).

Color in alcohol. Ground color pale yellowish, darker along mid-dorsal line, slightly lighter ventrally; some specimens (e. g. IMCN 4834) with lateral region of abdomen lighter, with silvery iridescence. Minute dark chromatophores covering body, less numerous on lateral and ventral regions of abdomen and ventral region of caudal peduncle. Dark midlateral stripe diffuse (silvery in specimens retaining guanine), extending from humeral region or vertical through pelvic-fin origin to caudal peduncle. Scattered dark chromatophores present along myosepta between lateral line and upper portion of anal fin. Humeral blotch absent, not differentiated from midlateral stripe of chromatophores. Diffuse blotch on caudal peduncle (absent in some specimens), similarlycolored to midlateral stripe of chromatophores on body flanks. Dorsal, anal, caudal, pectoral, and pelvic fins light gray, with scattered dark chromatophores on rays and/or membranes. Head darker dorsally than ventrally, some specimens with intense dark pigmentation posterodorsally (e. g. IMCN 4834). Chromatophores absent or reduced in number on opercle and infraorbitals. Premaxilla, anterior portion of maxilla, dentary, and lips with higher concentration of dark chromatophores. Variations in color pattern between males and females described under sexual dimorphism.

Color in life. Dorsum of body golden and/or yellowish. Silvery midlateral stripe on body flanks extending from posterior region of opercle to caudal peduncle. Ventral and dorsal borders of lateral stripe with shiny silveryyellow iridescence. Humeral blotch absent or diffuse. Blotch on caudal peduncle absent or continuous to midlateral stripe. Dorsal fin hyaline, with light orange pigmentation on distal portions of its rays. Adipose fin orange or reddish. Anal fin hyaline, some individuals with small red or black spots on first rays. Caudal fin mostly hyaline, with base yellowish and lobes orange or grayish. Pelvic fin hyaline. Pectoral fin with faint orange pigmentation on ray tips. Head yellowish dorsally, with metallic-green iridescence. Premaxilla, anterior portion of maxilla, dentary, and lips (especially on lower jaw) with intense black pigmentation and golden iridescence (based on specimens from IMCN 4834). Variations in color pattern between males and females described under sexual dimorphism.

Sexual dimorphism. Males with bony hooks on anal-, caudal-, and pelvic-fin rays. Caudal fin with short, slender, anterodorsally oriented hooks, especially on branched portions of rays 15–18 ( Fig. 8 C). Pelvic-fin rays (except unbranched and innermost rays) with short, slender, anterolaterally or anteroventrally oriented hooks, more numerous on branched portion of rays; hooks usually paired or one per segment (reduced in number and unpaired on bases of rays). Anal fin with slender, anterodorsally or anterolaterally placed hooks with broad bases; from 1 to 18 pairs per ray located from posteriormost unbranched ray and up to nine anterior branched rays (larger hooks on middle rays of this range). In adult males, middle anal-fin rays slightly longer than remaining rays, resulting in convex-shaped anal-fin margin. Females with anal-fin rays gradually decreasing in length from anteriormost branched ray to posteriormost branched ray; anal-fin margin somewhat concave or straight. Anal-fin base of adult males slightly concave or curved along its midlength, this base straight in females. Adult females rarely with short, externally developed urogenital papillae.

Posterior region of midlateral stripe less intense on ventral portion of caudal peduncle in males than in females. Males with intense dark (preserved color in fixed specimens), reddish or dark red pigmentation located on anterior and posterior regions of pelvic-fin origin and extending across ventral region of urogenital pore (one female observed with similar pigmentation). Mature males with hypertrophied scale forming pouch on lower caudal-fin lobe, with ventral procurrent rays 2 and 3 forming spur-shaped structure. Scarce small aggregations of apparent glandular tissue located on caudal-fin rays and medially to pouch scale. First ventral procurrent ray with moderate concavity on its ventral margin ( Fig. 8 C). Second ventral procurrent ray somewhat longer than third ray, reaching last third of first ventral procurrent ray, and somewhat flattened in sagittal plane, strongly on posterior portion). Posterior portion of third ventral procurrent ray weakly developed laterally. Pouch scale with 20–27 radii, usually located between caudal-fin rays 15 or 16 and third ventral procurrent ray. Posteroventral pouch-scale lobe well developed, extending along third ventral procurrent ray ( Figs. 8 C–D). Dorsal surface of pouch scale attached via soft tissue (possibly connective tissue) to caudal-fin rays 11 or 12 to 14. Posterior margin of pouch scale located between caudal-fin ray 14 or 15 and third ventral procurrent ray. Four scales in vertical series placed ventral to terminal lateral-line scale, overlapping posterior portion of pouch scale. Dorsal margin of pouch scale usually with small notch. Females with large scale with 15 (1), 16 (1), 17 (2), 18 (1), 19 (1), 20 (1), 22 (1), or 27 (1) radii on lower caudal-fin lobe.

Mature males with gill gland, formed by fusion of 8 (1), 9 (3), 10 (6), 11 (5), 12 (5), or 15 (1) anterior gill filaments of ventral limb of first gill arch. Total number of ventral limb gill filaments 17 (1), 18 (1), 19 (1), 20 (4), 21 (6), 22 (5), 23 (1), 24 (1), or 26 (1). Gill-gland length 2.7–5.4 % SL (mean = 4.1 % SL). Regression comparisons of morphometric data by sex with major differences in caudal peduncle depth (higher values in males than in females) ( Fig. 9 ).

Distribution. Gephyrocharax caucanus is distributed in drainages flowing into the upper Cauca River basin and Lake Calima, Pacific versant, Colombia ( Fig. 1 ).

Remarks. Eigenmann’s original description (1912) of G. caucanus did not report the precise drainage where the holotype was collected. The only geographic datum reported by Eigenmann (1912) was the city of Cartago, which is the type locality, but since this city is drained by several tributaries from the Cauca and La Vieja rivers, it was not possible to identify any particular drainage for the holotype.

The presence of Gephyrocharax caucanus is confirmed for the Lake Calima, Pacific versant of Colombia ( Maldonado-Ocampo et al. 2012; Maldonado-Ocampo et al. 2008; Mojica 1999; Weitzman 2003). The FUNINDES foundation is currently researching the possible transplant of some fish species (including G. caucanus ) from the Cauca River basin to the Lake Calima as part of a repopulation initiative by local authorities and fishers to promote the fishing (A. Ortega-Lara, Pers. Commun.). Therefore, the final results of this investigation can be crucial to corroborate or not the natural distribution of G. caucanus in the Pacific versant.

Material examined. All specimens from Colombia: CAS 44275 (previously IU 12668a–j), 10 paratypes, 44.5–50.0 mm SL, [Valle del Cauca, La Vieja River], Magdalena River basin, Cauca River basin, Cartago on Viejo River, six miles from Cauca River, approximately 4°45'12.00"N 75°52'30.00"W 993 m a. s. l. CAS 44276* (previously IU 12669a–e), 1 paratype, 50.2 mm SL, [Valle del Cauca], Magdalena River basin, La Paila River on Cauca River, La Paila, 31.25 miles upriver from Cartago, approximately 4°18'44.73"N 76°3'17.55"W 959 m a. s. l. CZUT-IC 1118, 4, 33.1–39.7 mm SL, Cauca, Cauca River basin, Silletero creek before Santander de Quilichao, approximately 3°5'27.85"N 76°28'15.29"W 992 m a. s. l. FMNH 56012* (formerly CM 4803a–j in part), holotype of Gephyrocharax caucanus , 49.4 mm SL (rad), female, [Valle del Cauca, upper Cauca River system], Cartago, approximately 4°45'12.00"N 75°52'30.00"W 993 m a. s. l. IAvH-P 3701, 4, Cauca, Silletero creek at the bridge on road between Cali and Santander de Quilichao, approximately 3°5'12.97"N 76°28'20.71"W 992 m a. s. l. IMCN 111, 4, 20.8–38.2 mm SL, Cauca, Timba, upper Cauca River, middle portion Zangón Bagazal, approximately 3°6'25.00"N 76°32'27.00"W 977 m a. s. l. IMCN 2260, 19, 18.8–40.7 mm SL (2 c&s 40.7– 34.2 mm SL), Cauca, Silletero creek before Santander de Quilichao, approximately 3°5'8.91"N 76°28'21.39"W 992 m a. s. l. IMCN 3084, 10, 32.1–39.8 mm SL (2 c&s 34.0–40.0 mm SL), Valle del Cauca, Jamundí, Cauca River system, Jamundí River, approximately 3°16'57.38"N 76°32'20.90"W 969 m a. s. l. IMCN 3183, 4, 34.6–41.8 mm SL, Risaralda, La Virginia, Cauca River, approximately 4°53'22.68"N 75°52'41.67"W 901 m a. s. l. IMCN 3407, 3, 37.9–41.1 mm SL, Risaralda, La Virginia, Cauca River before confluence with Risaralda River, approximately 4°53'29.99"N 75°53'22.76"W 896 m a. s. l. IMCN 4296, 3, 16.4–18.4 mm SL, Valle del Cauca, Calima, Darién, Lake Calima on wall of dam, approximately 3°53'24.71"N 76°29'54.26"W 1142 m a. s. l. IMCN 4302, 1, 39.0 mm SL, Valle del Cauca, Calima, Darién, Lake Calima on wall of dam, approximately 3°53'24.71"N 76°29'54.26"W 1142 m a. s. l. IMCN 4323, 1, 37.6 mm SL, Valle del Cauca, Calima, Darién, Lake Calima on wall of dam, approximately 3°53'24.71"N 76°29'54.26"W 1142 m a. s. l. IMCN 4834, 9, 23.0– 41.9 mm SL, Cauca, upper Cauca River, Silleteros creek on route toward Santander de Quilichao and to 200 m from club Los Andes, approximately 3°4'50.31"N 76°28'31.21"W 992 m a. s. l. MCZ 35811*, 1, 44.8 mm SL (rad), Valle del Cauca, Cauca River basin, La Paila River, approximately 4°19'15.30"N 76°3'48.92"W 960 m a. s. l. MCZ 35872*, 1, 48.5 mm SL (rad), Valle del Cauca, upper Cauca River tributaries (not georeferenced). USNM 81921 (possibly CM 4809a–j in part), 3 paratypes, 42.6–49.1 mm SL, [Valle del Cauca, upper Cauca River system, Cartago], “Carbago”, approximately 4°45'12.00"N 75°52'30.00"W 993 m a. s. l.

Figures

FIGURE 1. Geographic distribution of Trans-Andean species of Gephyrocharax occurring west from eastern versant of Andean Cordillera in northwestern South America to southern Central America.

FIGURE 6. Tukey box plots of (A) number of maxillary teeth, (B) number of branched anal-fin rays, (C) number of branched pelvic-rays, and (D) number of lateral-line scales comparing among Gephyrocharax species. Number of specimens between brackets.

FIGURE 7. Gephyrocharax caucanus, (A) female, holotype, 49.4 mm SL, FMNH 56012; (B) male, 38.9 mm SL, IMCN 4834; (C) female, 48.5 mm SL, MCZ 35872. White arrow indicates characteristic pigmentation of adult males.

FIGURE 8. Gephyrocharax caucanus, (A – B) upper and lower jaws, female, 39.8 mm SL, IMCN 3084, right side; (C – D) detail of lower caudal skeleton and associated pouch scale, male, 32.3 mm SL, IMCN 2260, left side. Anguloarticular: aa, dentary: dt, maxilla: mx, premaxilla: pm, pouch scale: ps, posteroventral lobe: pvl, principal caudal-fin ray: pcr, retroarticular: ra, spurshaped structure: sss, ventral procurrent ray: vpr. Lateral view. Scale = 1 mm.

FIGURE 9. Regression plot by sex of caudal peduncle depth as function of SL for Gephyrocharax caucanus (females, r = 0.98, r 2 = 0.96, ɑ = 0, β = 0.088, n = 31; males, r = 0.96, r 2 = 0.92, ɑ = 0, β = 0.097, n = 31).

Tables

TABLE 2. Morphometric data of holotype, paratypes, and other examined species of Gephyrocharax caucanus. Range of females and juveniles including holotype values. M = mean; SD = standard deviation.

Characters			Males		Females and unsexed juveniles
	Holotype	n	Range M	SD	n Range M SD
Standard length (mm)	49.4	37	25.5–44.8 34.1	3.9	38 18.8–50.2 39.9 9.0
Percentages of standard length:
Depth at dorsal-fin origin	27.5	31	20.5–28.3 24.7	2.0	31 21.3–28.3 24.9 2.0
Snout to dorsal-fin origin	66.6	31	62.0–67.6 65.9	1.3	31 63.9–70.2 66.5 1.5
Snout to pectoral-fin origin	23.1	31	24.1–27.6 25.3	0.8	31 22.8–27.9 24.6 1.2
Snout to pelvic-fin origin	44.3	30	41.2–45.1 43.2	1.2	31 40.5–47.1 43.9 1.3
Snout to anal-fin origin	56.9	31	55.0–60.5 57.2	1.5	31 54.4–60.9 58.2 1.5
Dorsal fin to pectoral fin length	49.2	31	43.5–48.9 46.3	1.3	31 43.9–52.1 47.6 1.9
Dorsal fin to adipose fin length	25.5	31	23.2–27.8 25.3	1.0	31 21.4–25.9 24.3 0.9
Dorsal fin to hypural complex length	36.0	31	32.8–39.0 35.8	1.2	31 27.4–37.4 34.4 1.8
Eye to dorsal-fin origin	56.1	31	51.0–56.8 54.0	1.4	31 48.0–58.2 55.2 1.9
Pectoral fin to pelvic fin length	21.5	30	16.6–20.3 18.2	0.9	31 17.2–22.4 19.8 1.4
Pelvic fin to anal fin length	13.6	30	13.2–17.3 14.9	0.9	31 12.7–17.4 15.1 1.3
Dorsal-fin length	17.6	31	16.3–20.6 18.2	0.9	31 14.7–19.4 17.9 1.0
Dorsal-fin base length	8.7	31	7.5–9.9 8.6	0.5	31 7.3–9.3 8.3 0.4
Pectoral-fin length	27.9	31	21.0–26.2 24.2	1.2	31 22.0–28.3 24.9 1.3
Pelvic-fin length	14.4	30	12.2–16.1 14.5	0.9	31 11.6–15.0 13.4 0.8
Anal-fin length	16.4	31	13.2–17.8 15.5	1.1	31 13.2–19.2 16.0 1.4
Anal-fin base length	39.3	31	33.7–40.9 37.0	1.5	31 33.5–39.3 36.8 1.3
Caudal peduncle depth	9.5	31	7.4–10.9 9.6	0.9	31 6.4–9.8 8.6 0.6
Caudal peduncle length	9.1	31	8.1–11.4 9.4	0.8	31 8.1–11.6 9.2 0.8
Bony head length	20.4	31	20.9–24.0 22.3	0.8	31 19.8–24.5 21.4 1.2
Percentages of head length:
Snout length	25.7	31	24.3–30.1 27.5	1.5	31 21.4–29.9 27.5 1.7
Horizontal eye length	30.7	31	32.9–40.8 34.9	1.7	31 29.8–39.9 33.7 2.3
Postorbital head length	45.5	31	36.7–44.3 40.1	1.9	31 38.4–45.5 42.1 2.0
Least interorbital width	33.7	30	27.5–33.7 30.6	1.4	29 27.1–33.7 31.0 1.8
Upper jaw length	39.6	31	37.5–42.8 40.0	1.3	31 37.6–42.6 40.3 1.4