Triportheus orinocensis, Malabarba, 2004

Malabarba, Maria Claudia S. L., 2004, Revision of the Neotropical genus Triportheus Cope, 1872 (Characiformes: Characidae), Neotropical Ichthyology 2 (4), pp. 167-204 : 194-196

Triportheus magdalenae ( Steindachner, 1878) Figs. 20 and 21

Chalcinus magdalenae Steindachner, 1878:88 , 91 (diagnosis; type-locality:”Magdalenen-stromes” [ Colombia, Río Magdalena]). Steindachner, 1879: 20, 60-61 (detailed description; Pl. 11, figs. 1-2: male, female, dentition).

Triportheus magdalenae . Miles, 1947:163-164

Diagnosis. An elongate Triportheus species reaching 199 mm SL (depth at dorsal-fin origin, 22.4-29.1% SL, n = 51; depth at pectoral-fin insertion, 25.7-32.5, n = 51). The presence of 1 longitudinal scale row between the pectoral-fin insertion and the ventral keel distinguishes this species from deepbodied Triportheus species that have 2 longitudinal scale rows between the pectoral-fin insertion and the ventral keel. This species can be further distinguished from all other Triportheus species by the high number of anal-fin rays (32-39).

Description. Morphometric data of Triportheus magdalenae presented in Table 15. Body elongate, distinctly compressed laterally. Greatest body depth located slightly posterior to vertical through pectoral-fin insertion. Dorsal profile of head nearly straight from margin of snout tip to rear of head. Dorsal profile of body in females convex from rear of head to dorsal-fin origin; posteriorly slanted from that point to caudal peduncle. Dorsal profile less convex in males from rear of head to dorsal-fin origin. Ventral profile of body distinctly arched from lower jaw tip to anal-fin origin; straight and posterodorsally slanted along base of anal fin; slightly concave along caudal peduncle. Prepelvic region between isthmus to pelvic-fin insertion distinctly expanded ventrally, with well-developed midventral keel.

Head obtusely pointed in profile; with posterior margin of the opercle reaching vertical through pectoral-fin insertion. Mouth terminal; lower jaw as long as upper. Gill rakers on lower limb of first arch 33-90 [73-87] (mean = 70.5, n = 49); 50- 90 in specimens over 60 mm SL (see Remarks).

Two rows of teeth on premaxilla; teeth of inner row larger. Inner tooth row with 7 tricuspidate to pentacuspidate teeth. Outer row with 5 teeth. Maxilla with 0 to 2 teeth smaller than smallest teeth on premaxilla. Dentary with 2 tooth rows; outer row with 7-8 teeth, decreasing in size posteriorly; dentary teeth with 3-5 cusps; inner row consisting of conical symphyseal tooth.

Scales cycloid, thin, and large. Lateral line distinctly decurved ventrally, completely pored from supracleithrum to base of caudal-fin rays. Thirty-eight to 42 scales in lateral line [38-39] (mean = 39.1, n = 47); 6-7 scale series between the lateral line and dorsal fin origin; 2 scale rows from lateral line to pelvic-fin insertion. A large scale present between pectoral-fin insertion and midventral keel; 11-17 [14-17] (mean = 14.1, n = 26) scales along mid-dorsal line between tip of su- praoccipital process and origin of dorsal fin. Four to 6 [4-5] rows of scales on caudal peduncle.

Dorsal-fin rays ii,9; anal-fin rays iii,32-39 [34-38]; pectoralfin rays i,10-12 [10-11]; pelvic fin rays i,6. Dorsal-fin base situated on posterior one-half of body; base of last dorsal-fin ray located anterior to vertical through anal-fin origin. Pectoral fin large, reaching vertical through tip of pelvic fin. First branched anal-fin ray longest; following rays rapidly decreasing in length. Caudal fin forked, lobes obtusely pointed; scaled only at base.

Total vertebrae 39-40 [39-40].

Color in alcohol. Overall color of specimens preserved in alcohol silvery yellow. Outline of posterior margin of caudal fin dark.

Remarks. Triportheus magdalenae is the only member of the genu s known from the río Magdalena drainage, Colombia. This species demonstrate a large degree of variation in body shape, length of the anal-fin base, and the number of gill rakers. The variation in body shape is apparently associated with sexual dimorphism. Male specimens have a more elongate body (body knife-shape) than females (body fusiform). However, only a few specimens could be dissected to confirm this observation and further analysis is necessary. Nonetheless the variation in body shape does not reveal any patterns that would justify the recognition of more than one species. Although the high number of gill rakers is distinctive for T. magdalenae , this number varies increasing ontogenetically, as shown in Figure 22.

Distribution. Río Magdalena basin ( Fig. 23 ).

Type-material examined. Chalcinus magdalenae : syntypes, NMW 69151 (7) , 141-199 mm SL, Colombia, Magdalena Strom (= río Magdalena), 31 Sep 1876; NMW 69152 (2) , syntypes, 153- 191 mm SL, Magdalena Strom , Colombia; 31 Nov 1876. NMW 69153 (4) , syntypes, 155-192 mm SL, Magdalena Strom , Cienaga [11.01°N 74.26°W], Colombia; 1876. NMW 69154 (2) , syntypes, 137 mm SL, Magdalena Strom , Colombia; 31 Nov 1876 .

Type-material remarks. In the original description of Chalcinus magdalenae, Steindachner (1878) did not provide information on the specimens that were the basis of the description nor note a specific type locality, only providing a general locality of “Magdalenen-stromes”(= Río Magdalena) for the several fishes listed in that publication. In a subsequent paper, Steindachner (1879) provided a detailed description with illustrations, and indicated that the collecting site (1879: 20) of the C. magdalenae was Cienaga. That location is situated in the Colombia coast near the mouth of the río Magdalena ( Fig. 23 , asterisk). Later, Steindachner (1880:79) provided a list of fishes from the río Cauca and along with a short description of Chalcinus magdalenae “ reported on “three specimens of 15-23 cm length”. This citation has been misinterpreted by some subsequent authors who cite the río Cauca as the type locality for this species ( Eschmeyer, 1998:1001). There are 15 specimens identified as syntypes of C. magdalenae deposited in NMW (NMW 69151 (7), NMW 69152 (2), NMW 69153 (4), and NMW 69154 (2), Mikschi and Wellendorf, pers. comm., 1999) and one syntype in the ZMC ( Nielsen, 1974), all collected in the río Magdalena.

Non-type material. Colombia: Magdalena: FMNH 56321 (5 of 9), Cienaga (10°15’N, 74°54’W) ; FMNH 69756 (10 of 91), Calamar (10°15’N, 74°54’W) ; FMNH 69628 (7 of 149), Soplaviento (10°22’N, 75°7’W) . Cundinamarca: FMNH 56324 (10), Girardot (4°0’N, 74°48’W) ; USNM 167797 (2), Girardot (4°0’N, 74°48’W) . Antioquia: MZUSP 42201 (2), río Cauca, Caucasia (8°0’N, 75°11’W) . Bolivar: USNM 175327 (6), río Viejo (8°1’N, 75°9’W) . Tolima: FMNH 88185 (16), Honda (8°38’N, 76°5’W) ; FMNH 56327 (5), Honda (8°38’N, 76°5’W) ; USNM 079182 (3), Honda (8°38’N, 76°5’W) ; USNM 116460 (1), Honda, Rio Magdalena basin (8°38’N, 76°5’W) ; FMNH 56328 (4 of 8), Puerta de Río , 1912; Manuel Gonzales [I have found no localities named Puerta de Río, in Colombia. According to Eigenmann (1922:4), Manuel Gonzales joined to his expedition from Bogota to Cartagena, but he listed no localities named Puerta de Río in his report (p.15-17)] .

Figures

Fig. 20. Triportheus magdalenae, MZUSP 42201, 151.58 mm, Colombia, Antioquia, río Cauca, Caucasia.

Fig. 23. Map of central and northern South America showing geographic distribution of Triportheus magdalenae (circles; asterisk = type locality), T. pantanensis (black squares; white square = type locality) and T. orinocensis n. sp. (triangles; white diamond = type locality) (some symbols represent more than one locality or lot of specimens).