Hyphessobrycon klausanni, Garcia-Alzate, Carlos A., Urbano-Bonilla, Alexander & Taphorn, Donald C., 2017

Garcia-Alzate, Carlos A., Urbano-Bonilla, Alexander & Taphorn, Donald C., 2017, A new species of Hyphessobrycon (Characiformes, Characidae) from the upper Guaviare River, Orinoco River Basin, Colombia, ZooKeys 668, pp. 123-138 : 125-129

Hyphessobrycon klausanni sp. n. Figures 1, 2, 3, 4

Holotype.

UARC-IC 539, 23.1 mm SL, male, Colombia, Meta, Mapiripán County, upper Guaviare River drainage, Caño Claro, 03°07'05.1"N; 72°30'14.8"W; 209 masl; Paratypes. UARC-IC 540, five, 22.1-24.2 mm SL, collected with holotype; UARC-IC 541, two CS, 20.2-22.3 mm SL, collected with holotype; UARC-IC 542, eight, 20.1-23.3 mm SL, Mapiripán county, upper Guaviare River drainage, Caño La División, 03°07'05.8"N; 72°32'36.7"W, 209 masl; UARC-IC 543, two, 25.1-28.4 mm SL, El Castillo County, upper Guaviare River drainage, Caño Hondo, 03°33'08.6"N; 73°47'17.9"W, 209 masl; UARC-IC 544, six, 22.1-23.4 mm SL, Mapiripán County, upper Guaviare River drainage, Caño División 2, 03°07'03.3"N; 72°32'32.5"W, 221 masl; MPUJ 7857, eight, 25.4-31.4 mm SL, El Castillo County, Caño Hondo, upper drainage of Guaviare River, 03°33'08.6"N; 73°47'17.9"W.

Diagnosis.

Hyphessobrycon klausanni sp. n. can be diagnosed from all other species of Hyphessobrycon , except of H. cyanotaenia , H. loretoensis , H. melanostichos , H. nigricinctus , H. herbertaxelrodi , H. eschwartzae , H. montogoi , H. psittacus , H. metae , H. margitae , H. vanzolinii and H. peruvianus , by having a wide, conspicuous, dark lateral stripe extending from the anterior margin of the eye across the head and body and continuing through the middle caudal-fin rays to their tips. It differs from the species excepted above in having a wider lateral stripe that covers three or four horizontal scale rows (vs. stripe covering just one or two scales rows); in having an orange-yellow stripe extending from the anterodorsal margin of the eye to the caudal peduncle above the dark lateral stripe in life (vs. red lateral stripe extending from the anterodorsal margin of the eye to the caudal peduncle above the dark lateral stripe in live H. heterorhabdus , H. amapaensis , H. eschwartzae and H. montagi ); by having fewer pored lateral line scales (three to four vs. five to10); fewer lateral scales (21 to 24 vs. 29 to 34); and in having more teeth on the inner premaxillary row (six vs. five). It differs from H. loretoensis in having seven to eight maxillary teeth (vs. three to four) and in having a longer caudal peduncle (12.4-17.0% SL vs. 4.6-8.0% SL). Additionally Hyphessobrycon klausanni can be distinguished from the other species of Hyphessobrycon with a dark lateral stripe from the Orinoco River Basin ( H. metae and H. acaciae ), in having: two teeth in the outer premaxillary row (vs. three to four see Fig. 2) and 10 branched pectoral-fin rays (vs. 11 to 12). It further differs from H. metae by the length of the snout (17.6-22.8% HL vs. 9.9-15.2% HL) and by the length of the caudal peduncle (12.4-17.0% SL vs. 7.3-11.8% SL).

Description.

Morphometric data shown in Table 1. Body compressed, moderately thick, greatest depth between pelvic-fin insertions and dorsal-fin origin. Dorsal profile of head straight from upper lip to vertical through middle of orbit; then convex to dorsal-fin origin. Dorsal-fin base convex, then slightly concave to adipose-fin origin, then straight to base of upper caudal-fin lobe. Ventral profile of head convex from lower lip to insertion of anal fin, anal-fin base straight and then slightly concave to base of lower caudal-fin lobe.

Head and snout long, jaws equal, mouth terminal, lips soft and flexible, outer row of premaxillary teeth not exposed. Premaxilla with long, sharp lateral process over ethmoids, with two rows of teeth: the external row with one (2) or two* (23), all tricuspid; inner row with six* (25) tricuspid teeth the gradually diminish in size away from symphysis. Maxillary long and narrow, posterior margin straight, anterior margin convex, ventral margin reaching anterior border of third infraorbital, with seven* (10) or eight (15) tricuspid and conical teeth. Dentary with convex ventral margin, four (25) frontal multicuspid teeth followed by six* (15) or eight (10) smaller conical teeth (Fig. 2).

Scales cycloid. Lateral line with three (10) or four* (15) pored scales. Lateral scale series with 21 (10), 22 (6) or 24* (9) scales, including those with pores. Transverse scales rows five* (25) between dorsal-fin origin and lateral line, not including the predorsal series just in front of first dorsal-fin ray. Four (25) horizontal scale rows from anal-fin origin to lateral line. Three (25) horizontal scale rows between pelvic-fin origins and lateral line. Predorsal scales nine*(18) or 10 (7). Five scales in single row along anterior anal-fin base. Fin rays: Dorsal ii, 9 (25). Anal iii, 19 (18) or 20* (7). Pelvic ii, 7 (25). Pectoral ii, 10 (25). Caudal 10+10 (2) principal and 10 (2) procurrent. Caudal fin bifurcate, upper and lower lobes similar in size, pointed. Total vertebrae 32-33.

Sexual dimorphism.

Males have hooks on anal-fin and pelvic–fin rays. Anal fin with pair of rows of eight to ten small hooks along third simple ray followed by two to eight pairs of hooks on first to fifth branched rays. Pelvic fins with two to ten pairs of hooks on branched rays, located above internal branch of ray, each segment of branched rays with pair of hooks.

Color in alcohol.

Opercular and humeral spots absent. Dorsal part of head and body to dorsal fin dark brown, then yellow on sides and light yellow ventrally. Base color divided by conspicuous, wide (three to four horizontal scale rows), dark lateral stripe from anterior margin of eye through middle caudal-fin rays. Pectoral, pelvic and anal fins hyaline. Dorsal, anal and caudal fins with dark margins. Anal fin with dark pigment concentrated on interradial membranes.

Color in life.

Body greenish-yellow, predorsal area orange-yellow, preventral area silvery-yellow, upper and lower margins of eye red and black respectively, dorsal area of head orange-yellow, ventral area greenish-yellow with great concentration of mel anophores on infraorbitals, preopercle and opercle. Wide, black, lateral stripe from anterior part of eye along sides through middle caudal-fin rays, covering at least half of body height near midbody. Iridescent orange stripe present above black stripe from eye to upper caudal-fin lobe. Lower lobe of caudal fin with orange iridophores at bases of rays. Bases of dorsal-fin rays orange, base of caudal and pelvic fins greenish–yellow. Adipose fin light orange (Fig. 3).

Distribution.

Hyphessobrycon klausanni is known only from the type locality in the upper Guaviare River Orinoco Basin in Colombia (Fig. 4).

Etymology.

Research leading to the discovery and recognition of this species was partially funded by Mr. Klaus-Peter Lang from Oberhausen, Germany. To commemorate the 80th birthday of his mother, this species is dedicated to and named for his father “Klaus” and his mother “Anni”.

Remarks.

Principal component analysis (PCA) detected morphological differences among Hyphessobrycon klausanni and H. acaciae , H. mavro , H. metae and H. niger . For the first component, upper jaw length, postorbital length and dorsal-pectoral fin distance were the most important variables. For the second component, orbital diameter, caudal peduncle length and snout length were most important. The first component explained 43.71% of total variation, and combined with the second this rose to 85.78% (Fig. 5, Tables 2 and 3).

Ecological note.

Hyphessobrycon klausanni lives in shallow (0.30-1.5 m) well-oxygenated (6.39-7.68 mg/l) streams with transparent waters flowing (0.063 m/s) over different types of substrates (rocks, sand, gravel and decomposing organic material). The temperature range was narrow, 25.5-26°C but pH varied from moderately acidic to basic (6.47-8.7). Hyphessobrycon klausanni was found near shore among aquatic vegetation, tree roots and fallen logs. Other species found at the sites included: Hemigrammus barrigonae , Ctenobrycon spilurus , Tyttocharax metae , Moenkhausia oligolepis , M. chrysargyrea , M. lepidura , Chrysobrycon guahibo , Ochmacanthus orinoco , Farlowella vittata , Ancistrus triradiatus , Centromochlus reticulatus and Anablepsoides sp. Stomach content analysis (n = 4) revealed a diet of aquatic and terrestrial invertebrates: Coleoptera ( Dytiscidae ), Ephemeroptera , Hymenoptera ( Formicidae ), larvae of Chironomidae and others not identified due to the degree of fragmentation.