Hyphessobrycon oritoensis, García-Alzate, Carlos A., Román-Valencia, César & Taphorn, Donald C., 2008

García-Alzate, Carlos A., Román-Valencia, César & Taphorn, Donald C., 2008, Hyphessobrycon oritoensis (Characiformes: Characidae), a new species from the Putumayo River drainage, Colombian Amazon, Zootaxa 1813, pp. 42-50 : 43-47

Hyphessobrycon oritoensis , new species

Table 1, Figs. 1–3

Holotype: IUQ 1574, 24.63 mm SL; Colombia, Putumayo, Orito, Quebrada La Palma, finca La Palma, Vereda Calimonte, 29 Jun. 1998. Approximately 0º 41’ N & 75º 52’ W. C. Román–Valencia, J. Tovar & H. Hoyos.

Paratypes: IUQ 139, (6 ex.) collected with the holotype. IUQ 1575, (2 ex.) (C. & S.) collected with the holotype; MBUCV – V 33737 , (2 ex.) collected with the holotype; MCNG 55844, (2 ex.) collected with the holotype; Colombia, Putumayo, Orito, Quebrada La Palma, finca La Palma, Vereda Calimonte, 29 Jun. 1998. Approx. 0º 41’ N & 75º 52’ W. C. Román–Valencia, J. Tovar & H. Hoyos. 26.19-42.77 mm SL.

Diagnosis: Hyphessobrycon oritoensis is distinguished from all congeners by having three simple and eight branched rays in the dorsal fin (vs. two simple and nine branched rays, except H. notidanos which has iii, 8); four simple and 26–27 branched anal–fin rays (vs. three simple and 17–24 branched rays); 19 teeth on the dentary (vs. 6–12); 35 lateral line scales (vs. 31–34, except for H. heterorhabdus which has 37); 10-11 pored lateral–line scales (vs. 8–9); seven longitudinal scale rows from the lateral line to the dorsal fin (vs. five, except in H. heterorhabdus with seven) and fourteen predorsal scales (vs. 10–11). Hyphessobrycon oritoensis is distinguished in detail from H. notidanos in the “Remarks” section below.

Description: Morfometric and meristic data are given in Table 1. Body short and deep, dorsal profile of head and body oblique from snout to supraoccipital, convex from there to dorsal fin origin, and from the last dorsal–fin ray to the base of the caudal fin. Ventral profile of body convex from snout to base of anal fin, more pronounced behind pectorals. Head and snout short; mandibles equal; mouth subterminal; lips soft and flexible, not covering the external row of premaxillary teeth; ventral part of the upper jaw flat; posterior end of maxilla passing anterior border of orbit.

Premaxillary with a long lateral process, pointed and with two rows of teeth ( Fig. 2 ); the external row with 3–4 tricuspid teeth arranged in zig zag; the internal row with 5–6 tricuspid teeth, diminishing gradually in size from inner to outer laterally. Maxilla long with 5–6 tricuspid teeth, and with posterior end reaching the posterior edge of second infraorbital; maxilla with two small foramina near upper margin of the tooth series. Two pentacuspid teeth in front of dentary, followed by three tricuspid lateral teeth larger than the rest, followed by 14 small conic teeth.

Six infraorbitals, the third longest in width, wide but not in contact with the sensory canal of preopercle; fourth infraorbital the smallest of series. Antorbital with anterior border concave. Supraorbital absent.

Rhinosphenoid heavily ossified, united with orbitosphenoid by a band of cartilage that extends above its posterior border; cartilage band extends to the dorso–anterior end and is in contact with the postero–dorsal margin of the prevomer. Orbitosphenoid heavily ossified with a round apophysis on anterior part. Paraesphenoid not divided, united to ventral surface of vomer; posterior end of parasphenoid in contact with prootic and basioccipital through a band of cartilage. Metapterygoid with upper margin wide and two crests, a small foramen in postero–medial region, with a band of cartilage along anterior and posterior edges. Ectopterygoid elongate and wide, in contact via cartilage with the quadrate. Nasal bone present. Basihyal cartilaginous and divided in two. Pharyngeal plate elongate and curved, having cartilage on the dorsal and antero–ventral edges. 16 gill rakers on first arch.

Total number of vertebrae 34–35. Proximal dorsal pterygiophores inserted between neural spines 10 and 17; 28 radial pterygiophores in anal fin. Four to five supraneurals present with cartilage on their dorsal and ventral ends. Pectoral girdle with a pointed dorsal elongation. Cleithrum elongate, widening near posterior edge and with the margin wavy, located below the ventral edge of the opercle. Scapula united to internal surface of cleithrum by cartilage. Postcleithrum 3 elongate and curved with a rounded laminar bony prolongation of its postero–medial edge. Four proximal radials present.

Edge of dorsal fin oblique. Pelvic fin short, tip not reaching anal-fin origin. Pelvic bone elongate and straight, parallel to medial area of body with cartilage on anterior and postero-lateral edges; ischial process short, curved, with pointed apophysis cartilaginous. Caudal fin forked, with long pointed lobes, scaleless. Principal caudal rays 9/8 (n=14).

Sexual dimorphism. No apparent sexual dimorphism was observed.

Color in alcohol: Body light yellow, lateral portion of body with dark band from behind humeral spot to tips of central caudal fin rays, wider beneath dorsal fin origin. Humeral spot dark. Guanine present dorsally and laterally in many specimens. Posterior edge of scales on dorsum and upper side black. Tip of caudal lobes dark. Dorsal, anal, pectoral and pelvic fins hyaline. Anal fin lightly pigmented at tips of rays. Head darker than body.

Distribution: Only known from the type locality.

Etymology: Named for the collection site, the Orito River in the Putumayo drainage, Amazonía, Colombia.

Remarks: The new species is very similar to H. notidanos , however it differs from it in the number of lateral scales (35 vs. 32–34 in H. notidanos ), in the number of pored scales (12–14 vs. 9–11), in the number of scale rows between dorsal–fin origin and lateral line (7 vs. 6), in the number of predorsal median scales (12– 14 vs. 9–11), in the number of teeth in the dentary (19 vs. 7), in the number of teeth in the maxillary (5–6 vs. 2–4) in the dorsal–fin rays (iv, 26–27 vs. iii, 17–20), in body depth (37.84–5.59% LS vs. 36.84–37.79% LS) and in the snout–anal fin distance (56.71–65.05% LS vs. 62.52–80.39% LS).

Principal components analysis (fig. 3) indicates that Hyphessobrycon oritoensis n. sp. is distinguished from Hyphessobrycon poecilioides , H. heterorhabdus , H. vilmae , H. melanostichos , H. diancistrus and H. notidanos in axis 1 by caudal peduncle depth in relationship to upper jaw length; and in axis 2, by body depth vs. dorsal fin–anal fin length. The first component explains 89.60% of the total variance, and combined with the second component they explain 92.74% of total variability.

Ecological notes: Data obtained from two stomachs of cleared and stained specimens indicates that this species is probably mostly insectivorous, feeding on allocthonous material, with unidentified insect parts being the most important element (56% by Number of prey items and 31% by Volume), followed by odonate larvae (8% N and 10% V), vegetable matter (16% N and 11% V) and unidentifiable material (20% N and 48% V). Their habitat had clear water over a substrate of sand and stone, with low dissolved oxygen (5.2 mg /l), 67% saturation and pH 6.0.

Figures

FIGURE 1. Hyphessobrycon oritoensis. Holotype; 34.63 mm SL; Colombia, Putumayo, Rio Orito, Amazon basin.

FIGURE 2. Upper (A) and lower jaws (B) of Hyphessobrycon oritoensis, IUQ 1575, paratype.

FIGURE 3. Principal components analyses (PCA) (component 1 in the axis X, component 2 in the axis Y) of morphometics data in Hyphessobrycon oritoensis n. sp (+), H. poeciloides (Π), H. heterorhabdus (), H. vilmae (), H. melanostichos (), H. diancistrus (*) and H. notidanos (Ϛ)