Neblinichthys echinasus, Taphorn & Armbruster & López-Fernández & Bernard, 2010

Taphorn, Donald C., Armbruster, Jonathan W., López-Fernández, Hernán & Bernard, Calvin R., 2010, Description of Neblinichthys brevibracchium and N. echinasus from the upper Mazaruni River, Guyana (Siluriformes: Loricariidae), and recognition of N. roraima and N. yaravi as distinct species, Neotropical Ichthyology 8 (3), pp. 615-615 : 615-

Neblinichthys echinasus , new species

Fig. 3

Holotype. CSBD 1652 , ex ( ROM 83713), 82.9 mm SL, presumably male, Guyana, upper Mazaruni River drainage, Kukui River, near town of Philipai, 05°21’37”N 60°22’18”W, 17 Apr 2008, H. López- Fernández, D. Taphorn, E. Liverpool, K. Kramer & C. Thierens.

Paratypes. ROM 84965, 1 , 57.5 mm SL, presumably male, same data as holotype . AUM 49999 (ex ROM 83692), 1, 50.0 mm SL, immature, upper Mazaruni River drainage, Kukui River, night collection near Philipai, 05°21’37”N 60°22’18”W, 15 Apr 2008, D. Taphorn, E. Liverpool & C. Thierens .

Diagnosis. Neblinichthys echinasus can be separated from all other Neblinichthys except N. brevibracchium , by having a pigmentation pattern on the abdomen consisting of large white spots and vermiculations over a dark gray or black background in adult males (vs. abdomen with small brown spots and vermiculations or plain); by lacking odontodes on the opercle (rarely one odontode present, vs. the exposed portion of the opercle completely covered by odontodes), by completely lacking the iris operculum (vs. iris operculum small or at least the dorsal rim of the pupil straight), and internares width/head length (6.2-6.7% vs. 7.6-15.5%, see Tables 1-2). It is distinguished from N. brevibracchium by a larger dorsal- 620 Description of Neblinichthys brevibracchium and N. echinasus

landmarks inArmbruster (2003). Some N. roraima have completely adnate barbels, resulting in a measurement of zero for barbel length. fin base/SL ratio (24.3-27.0% vs. 18.1-22.8%), a smaller dorsalanal distance/SL ratio (11.9-12.5% vs. 13.7-18.3%), by having the snout tapering shallowly and continuously from eyes to snout tip (vs. snout decreasing in steep arc just anterior to eyes and then flattening in area anterior of nares; Fig. 3 ), and by having the adpressed dorsal fin reaching the anterior preadipose plate (vs. not reaching anterior preadipose plate). From N. pilosus and N. roraima by having the odontodes along the edge of the snout of nuptial males longer than those on the top of the snout (vs. odontodes on the front edge of the snout much longer than those on the sides of the snout; nuptial males not known for N. brevibracchium or N. yaravi ); from N. roraima by having one to two preadipose plates (vs. more than four).

Description. Morphometrics presented in Table 1. Meristics based on three known specimens, largest 82.9 mm SL. Body dorsoventrally flattened. Profile from tip of snout sloping posterodorsally to nares, slightly concave between eyes to posterior margin of supraoccipital; gently convex to dorsalfin origin. From deepest point of body (just anterior to dorsalfin origin), profile slopes gently ventrally in straight line to base of caudal-fin spine. Ventral surface flat or slightly concave to anal-fin origin then straight or slightly concave to base of lower caudal-fin spine. Eyes widely separated, almost completely dorsally oriented, not visible from below. In dorsal profile, head margin forms broad U -shape. Body widest just behind pectoral-fin insertion, not narrowing until reaching pelvic-fin insertions, and then tapering to end of caudal peduncle.

Cheek plates strongly evertible (to 90° from head), with very numerous elongate as well as even more numerous short and medium sized odontodes, longest reaching base of second or third pectoral-fin ray. Snout with slightly rounded ridges from eye to just anterior to nares. Mesethmoid forming rounded ridge along midline anterior to nares. Dorsal rim of orbit slightly higher than interorbital space. Iris operculum absent, making dorsal rim of pupil round.

Mouth moderate in size with narrow premaxillary and dentary tooth cups forming gentle arcs. Premaxillary teeth 34-59; dentary teeth 33-62. Teeth villiform and bicuspid with very short cusps (medial cusp longer than lateral cusp). Edge of oral disk scalloped, and extending to vertical through anterior margin of eye, not extending beyond lateral margins of head. Enlarged

D. C. Taphorn, J. W. Armbruster, H. López-Fernández & C. R. Bernard 621

central papilla present in buccal cavity. Maxillary barbel very short, almost completely adnate. Ventral surface of lips papillose. Papillae largest in center of lower lip, decreasing in size radially. No enlarged papillae located behind dentary teeth.

Dorsal fin II,7; dorsal-fin spinelet visible as flat platelet with short odontodes; dorsal-fin lock functional. Dorsal fin short, just reaching preadipose plate when adpressed. First dorsal-fin ray slightly longer than dorsal-fin spine. Pectoral fin I,6; pectoral-fin spine short (slightly shorter or equal to pelvic-fin spine) not reaching pelvic fin when adpressed. Pectoral-fin spine relatively weak with odontodes numerous and of equal size along entire length. Anterior pectoral-fin rays longer than pectoral-fin spine, decreasing to about half of length of spine posteriorly, covered with odontodes that are largest on dorsal margin. Pelvic fin I,5; pelvic-fin spine thickened and covered with odontodes, reaching middle of 622 Description of Neblinichthys brevibracchium and N. echinasus

holotype dark brown with bold white to cream colored vermiculations and spots. Ventrum of paratypes plain tan. Oral disk with inner papillated surfaces pale tan but brown with white spots on outer anterior margin. All fin spines and rays with alternating wide dark and narrow light bands (pattern most evident in caudal and dorsal fins, least evident in pectorals); fin membranes dark gray in holotype, hyaline in paratypes. Base of anteriormost dorsal-fin membrane black ( Fig. 3 ).

base of anal fin when adpressed; anterior pelvic-fin rays longer than pelvic-fin spine with posterior margin of fin curving out beyond posterior tip of spine. Anal fin I,5; all anal-fin rays longer than weak spine. First anal-fin pterygiophore not exposed to form plate-like structure. Adipose-fin spine straight to slightly curved posteriorly with adipose membrane extending beyond posterior extent of spine. Caudal fin I,14,I; upper caudal-fin spine shorter than first two upper rays, lower spine longer than all rays, and much longer than upper spine. Dorsal procurrent caudal-fin rays five, ventral procurrent caudal-fin rays three. Posterior caudal-fin margin oblique or slightly concave. Rays of all fins supporting small odontodes.

Median plate series with 21-23 plates. Ventral plates forming gentle arc on caudal peduncle and not forming strong rounded keel. Three rows of plates on caudal peduncle (middorsal and mid-ventral plate series ending at level of adipose fin). Abdomen naked.

Coloration in alcohol. Head, dorsum of body and sides mostly brown with irregular lighter tan blotches. Holotype dark brownish gray with horizontal rows of light spots from behind pectoral-fin insertion to caudal fin on sides. Largest paratype with alternating light and dark brown patches. Ventrum of Sexual dimorphism. Presumed males have extremely hypertrophied odontodes along the entire edge of the snout with the odontodes becoming slightly shorter posteriorly. just prior to the evertible cheek plates ( Fig. 3 ). Three rows of hypertrophied odontodes on present on the snout, the medial row is relatively short and located on the mesethmoid; the lateral rows are also relatively short, extending from eyes to nares and then intermediate from nares to snout. The areas between the snout edge and the rows of odontodes have some hypertrophied odontodes, but not as densely packed. The remainder of the dorsal and lateral surfaces of the head have slightly elongated odontodes. Odontodes on the lateral plates are very slightly lengthened in nuptial males. No hypertrophied odontodes are present on the pectoral-fin spines. Presumed males have bolder marking on the abdomen.

Distribution. Known from upper Mazaruni River drainage, Guyana ( Fig. 2 ).

Etymology. From the Latin words echinus meaning sea-urchin or prickly and nasus meaning nose, in reference to the numerous odontodes that adorn males of this species. Epithet used as a noun in apposition, in masculine form.

Figures

Fig. 3. Neblinichthys echinasus, holotype, CSBD 1652, 82.9 mm SL, Kukui River, near town of Philipai, upper Mazaruni River drainage.

Fig. 2. Distribution of Neblinichthys species in the Caroní and Mazarunibasins of VenezuelaandGuyana,respectively.Star = N. roraima,black circle=N.yaravi,empty circle=type-localityof N. echinasus, new species, empty square = type-locality and black squares = paratype localities of N. brevibracchium, new species.