Hypostomus sculpodon, Jonathan W. Armbruster, 2003

Jonathan W. Armbruster, 2003, The species of the Hypostomus cochliodon group (Siluriformes: Loricariidae)., Zootaxa 249, pp. 1-60 : 49-51

Hypostomus sculpodon new species

(Fig. 21)

Holotype: VENEZUELA, Amazonas, Río Casiquiare, Río Negro dr. Departmento Río Negro, at Piedra Carguana (at second camp, left descending bank of river in portion of river between mouths of Río Siapa and Río Pasimoni), 01°58.611’N, 66°32.359’W, MCNG 37042, 1, (239.7 mm SL).

Paratypes: VENEZUELA. Amazonas: Caño Cascacadura, Río Orinoco dr. 7 km E of San Fernando de Atabapo, MBUCV V-8151, 2, (85.8-93.0) . Río Casiquiare, Río Negro dr. Departmento Casiquiare, lake adjacent to area approximately 15 river miles above mouth, of Río Casiquiare, 01°58’N, 66°55’W, MCNG 12148, 1, (166.8) . Río Casiquiare, Río Negro dr. Departmento Río Negro, 25 km from confluence with Río Negro, MCNG 37031, 1, (229.4), Paratype .

Diagnosis: Hypostomus sculpodon differs from all other members of the H. cochliodon group except H. hemicochliodon in the presence of a buccal papilla and intermediately developed teeth (Fig. 1B; juvenile H.cochliodon and H. taphorni occasionally also have intermediate teeth). Hypostomus sculpodon differs from H. hemicochliodon in coloration(brownish-red with widely spaced spots vs. dark brown with closely spaced spots), by having a smaller dorsal-anal length to anal-fin length ratio (average = 79.2 ± 7.6%, 69.6-89.7% vs. average = 111.1 ± 8.4%, 92.5-132.6%), and almost completely by having a smaller interorbital width/HL ratio (average = 51.4 ± 3.1%, 38.5-45.4% vs. average = 49.9 ± 2.7%, 44.1-55.6%).

Description: See description of the Hypostomus cochliodon group for more details. Morphometric data given in Table 5. Color red-brown. Body and fins well spotted, spots widely spaced. Spots on head and anterior portion of body (to about anterior third of dorsal fin) medium-sized, then shifting abruptly to large spots on posterior part of body. Spots on posterior part of body not progressively increasing in size, generally longitudinally ovoid. Abdomen significantly lighter than sides with spots large. Juveniles colored similarly to adults, but all spots of about the same size (except small spots at anterior margin of head), and abdomen much lighter with spots faint or absent.

Dorsal fin fairly large, usually reaching preadipose plate when depressed. Pectoral-fin spine, when depressed ventral to pelvic fin, reaching 2-3 plates beyond pelvic-fin rays. Tip of pectoral-fin spine of nuptial males with stout, recurved, hypertrophied odontodes.

Keels strong with sharp odontodes. Orbits forming ridge distinctly raised above medial surface of head; ridges of dorsal and lateral aspect of head well-developed, particularly supraoccipital crest. Longitudinal ridge formed of raised bone and slightly larger odontodes present and very well developed on pterotic-supracleithrum beginning at postdorsal corner of orbit. Opercle broadly exposed, always supporting much more than 10 odontodes. Nuptial body odontodes absent (Fig. 2A). Plates in skin anterior to dorsal-fin spine absent or few (Fig. 6A; Table 7). Head and body not particularly deep, body more sleek than other members of the H. cochliodon group.

Each jaw with 12-19 teeth (mode = 14), teeth intermediate in size (Fig. 1B). Average angle between dentaries 67° (SD = 11°; range: 56°-83°; N=5). Lateral line plates 30; dorsal plates 9-10; interdorsal plates 7-8; adipose caudal plates 9.

Range: Found in the upper Río Negro and upper Río Orinoco basins of Venezuela (Fig. 11). Hypostomus sculpodon is sympatric with H. hemicochliodon .

Etymology: From the Latin, sculpo, meaning to carve, cut, grave, or chisel in stone, brass, or wood and from the Greek, odon, for tooth in reference to the ability of the species to chisel wood with the teeth.