Sternarchorhynchus galibi, Santana & Vari, 2010

Santana, Carlos David De & Vari, Richard P., 2010, Electric fishes of the genus Sternarchorhynchus (Teleostei, Ostariophysi, Gymnotiformes); phylogenetic and revisionary studies, Zoological Journal of the Linnean Society 159 (1), pp. 223-371 : 298-299

STERNARCHORHYNCHUS GALIBI SP. NOV.

( FIGS 35 , 39 ; TABLE 6)

Diagnosis: Sternarchorhynchus galibi is distinguished from congeners by the following combination of characters: a short gape that terminates posteriorly at, or slightly short of, the vertical through anterior nares, the absence of scales along the mid-dorsal region of the body as far posteriorly as the vertical through the posterior limit of the pectoral fin, the presence of a more lightly coloured narrow band of mid-dorsal pigmentation on the head and mid-dorsal region of the body extending as far posteriorly as the origin of the electroreceptive filament and sometimes beyond that point, the presence of six to ten premaxillary teeth, 26–31 anterior unbranched anal-fin rays, 169–179 total anal-fin rays, and seven to ten scales above the lateral line at the midbody, the termination of the electroreceptive filament at the vertical running through a point one or two scales anterior of the posterior limit of the base of the anal fin, the termination of the lateral line at a point three or four scales anterior of the base of the caudal fin, the greatest body depth (11.1–12.7% of LEA), the caudal length (8.7–10.8% of LEA), the distance from the anus to the anal-fin insertion (6.8–12.8% of HL), the head width (17.9–23.3% of HL), eye diameter (3.9–6.7 of HL), the head depth at the eye (26.2–30.8% of HL), the head depth at the nape (39.5–47.6% of HL), the postocular distance (35.6–39.8% of HL), the pectoralfin length (31.5–40.7% of HL), and the tail depth (13.8–19.2% of caudal length).

Description: Morphometric data for examined specimens in Table 6.

Lateral line extending posteriorly to point three or four scales anterior of base of caudal fin but absent on remainder of tail and on caudal fin. Snout elongate, compressed and slightly curved ventrally along anterior portion. Mouth terminal. Rictus located along vertical through anterior naris. Anus and urogenital papilla located ventral to head, with position in smaller specimens located within area delimited anteriorly by vertical running approximately to eye and posteriorly one orbital diameter posterior of eye. Openings positioned one eye diameter anterior to vertical through eye in larger individuals. Combined opening for anus and urogenital papilla circular in smaller individuals and longitudinally ovoid in larger specimens.

Premaxilla with six to ten teeth (N = 4) apparent in whole specimens. Dentary with two tooth rows; outer row with six to nine teeth and inner row with one to three teeth (N = 4).

Branchiostegal rays five; with first to third rays narrow and elongate and fourth and fifth rays large and broad. Precaudal vertebrae 15–16 (11–12 anterior; four transitional; N = 2).

Pectoral-fin rays ii + 12–13 [ii + 12] (N = 10). Analfin origin located anterior to opercle. Anterior unbranched anal-fin rays 26–31 [26] (N = 8). Total anal-fin rays 169–179 [175] (N = 10). Scales above lateral line at midbody seven to ten [10] (N = 10). Scales absent along mid-dorsal region of body from rear of head posteriorly to point approximately onethird of distance along length of body and three times length of pectoral fin from rear of head. Scaleless region followed by fully scaled mid-dorsal area to origin of midsaggital electroreceptive filament. Origin of midsaggital electroreceptive filament located on posterior half of body, approximately 70% of TL. Filament extending to point one or two scales short of vertical through posterior terminus of base of anal fin to vertical through latter landmark. Tail compressed and short, ending in small, elongate, pointed caudal fin. Caudal-fin rays 15–17 [15] (N = 9).

Coloration in alcohol: Overall coloration of head and body dark brown. Slightly darker bands of pigmentation extending anteriorly from eye along dorsolateral portion of snout and along ventral portions of snout. Dark bands border more lightly pigmented region on midlateral surface of anterior half of snout. Dorsal dark band forms lateral margin of narrow, lightly coloured stripe running along middorsal region of snout; stripe terminates above eye, or slightly posterior of that point. Mid-dorsal stripe on snout separated from mid-dorsal stripe on body by dark pigmentation on dorsal surface of head in postocular region. Body with more lightly pigmented, mid-dorsal stripe extending from rear of head to origin of electroreceptive filament or to varying degrees posterior of that point. Pectoral fin dusky with small, dark chromatophores overlying fin rays. Anal fin dusky with small, dark chromatophores overlying fin rays. Caudal fin dark with distal regions hyaline.

Distribution: Sternarchorhynchus galibi is known from the Lawa River, Marowijne River (= Fleuve Maroni) basin along the border between Suriname and French Guiana ( Fig. 35 ).

Secondary sexual dimorphism: No sexual dimorphism was apparent in the limited available sample of S. galibi .

Etymology: The species name, galibi , is in reference to the town of that name begun as a major settlement of the indigenous Caribs. The town is at the mouth of the Marowijne, the drainage system that includes the type locality of S. galibi .

Remarks: Sternarchorhynchus oxyrhynchus was cited by Meunier (2004: 89) as occurring in the upper portions of the Fleuve Maroni (= Marowijne River in

French Guiana); however, it is likely that this citation was based on S. galibi .

Material examined

Holotype: – SURINAME. Marowijne District: Lawa River at Stroomafwaarts Rapids near Anapaikekondre (= Anapaike country; Anapaike at 3°34′N, 54°39′W), collected by J. P. Gosse, 18.xi.1966, ZMA 109.366 (168, originally part of IRSCNB 16793, apparently female).

Paratypes: – SURINAME. Marowijne District: Lawa River at Stroomafwaarts Rapids near Anapaikekondre (= Anapaike country; Anapaike at 3°34′N, 54°39′W), ZMA 124.524, 1 (121), IRSCNB 16793, 7 (80–202); collected with the holotype by J. P. Gosse, 18.xi.1966. Lawa River base camp, approximately 8 km south-south-west of Anapaike / Kawahaken (airstrip) (3°19′31″N, 54°03′48″W), collected by J. Lundberg, M. Sabaj, P. Willink, and J. Mol, 18.iv.2007, ANSP 187155, 1 (200) .

Nontype specimen: – FRENCH GUIANA. Upper Maroni River (no specific locality), MHNG 2167.45, 1 (143).

Figures

Figure 35. Map of central and northern South America showing geographical distribution of Sternarchorhynchus curumim, Sternarchorhynchus curvirostris, Sternarchorhynchus freemani sp. nov. (1 = holotype locality), Sternarchorhynchus galibi sp. nov. (2 = holotype locality), and Sternarchorhynchus gnomus (some symbols represent more than one locality and/or lot of specimens).

Figure 39. Sternarchorhynchus galibi sp. nov., holotype, female, 168 mm total length, ZMA 109.366; Suriname, Marowijne District, Lawa River at Stroomafwaarts Rapids near Anapaikekondre.