Hypoptopoma brevirostratum, Aquino & Schaefer, 2010

Aquino, Adriana E., 2010, Systematics Of The Genus Hypoptopoma Günther, 1868 (Siluriformes, Loricariidae), Bulletin of the American Museum of Natural History 2010 (336), pp. 1-110 : 43-48

Hypoptopoma brevirostratum , new species Figure 26 , table 6

HOLOTYPE: FMNH 105076 (♀, 34.0 mm

SL) Colombia: Rio Amazonas, 1 mi. up- stream from Leticia; collected by Navarro, Thomerson et al., 11 November 1973.

PARATYPES (collected with holotype): FMNH 117744 (14 ♀ + 4 ³, 29.1–39.3 mm SL). AMNH 243577 (1 ♀ + 1 ³, 33.2–34.0 mm SL).

NON- TYPES: BRAZIL, Amazonas: INPA 14317 (11 ♀ + 2 ³, 2 cs, 24.1–32.1 mm SL) Rio Solimões, 1 km acima do Furo Paracuuba ; INPA 14322 (1 ♀, 38.3 mm SL) Ihla Marchantaria. MZUSP 7015 (1 ♀, 28.2 mm SL) Rio Madeira, 25 km abaixo de Nova Olinda ; MZUSP 36214 (1 ♀ + 1 ³, 29.0–44.0 mm SL) Rio Japura, Manacabi, approximatly 50 km from Foz ; MZUSP 36221 (4 ♀, 25.5–38.00 mm SL) Braço do Rio Solimões, Ihla Sorubim, acima do Coari ; MZUSP 56820 (1 ♀; 30.6 mm SL) Rio Juruá, 10,2 km abaixo do Lago Pauapix- una. ECUADOR, Napo: FMNH 101541 (1 ♀ + 3 ³, 41.0– 50.6 mm SL) Río Jivino , lower 4 km (mostly) to ca. 6 km upstream from mouth. PERU, Loreto: INHS 44126 (1 ♀, 48.8 mm SL) Río Napo and Quebrada Mazán , 33.3 km NE Iquitos ; ANSP 187332 (1 ♀ + 1 ³ + 2 juveniles, 29.6–49.0 mm SL) Río Itaya at bridge on Iquitos- Nauta highway, approx. 25 miles SSW of Iquitos ; SIUC 27969 (1 ³, 41.8 mm SL) Río Mazán .

TABLE 6 Morphometric and Meristic Data for Hypoptopoma brevirostratum Holotype: FMNH 105076 . Paratypes: FMNH 117744 ; AMNH 243577 . Nontypes: FMNH 101541 ; INHS 44126 ; INPA 14317 ; SIUC 27969 .

DIAGNOSIS: Hypoptopoma brevirostratum is distinguished from all congeners, with the exception of H. muzuspi , by having the preopercle constricted medially (vs. preopercle with no constriction); canal in preopercle present, semicircular, located posterior to the preopercle constriction (vs. canal absent from preopercle). Hypoptopoma brevirostratum is distinguished from H. muzuspi by its wider body (cleithral width 23.7–27.0 (25.7) vs. 19.1–23.5 (22.2)), a deeper caudal peduncle (caudal-peduncle depth 6.4–9.1 (7.7) vs. 5.2– 6.7 (5.8)), and a larger eye (horizontal eye diameter 19.8–23.3 (21.7) vs. 13.6–20.7 (18.4)).

DESCRIPTION: Morphometric and meristic data presented in table 6. Body moderately wide and depressed; greatest depth at dorsalfin origin. Dorsal profile of head and body, from tip of snout to dorsal-fin origin, smoothly convex to straight; straight posterior to dorsal-fin base. Head moderately depressed, almost as wide as cleithral width; lateral process of lateral ethmoid not visible dorsally. Snout rounded and short in dorsal view; dorsally slightly concave anterior to naris. Posterior surface of bony pit of nasal organ sharply inclined. Body cross section between pectoral- and pelvic-fin origins approximately ovoid horizontally, slightly rectangular posterior to dorsal fin, slightly compressed at level of two posteriormost lateral trunk plates.

Eyes large, positioned equally distant from posterior tip of compound pterotic and to tip of snout. Ventral margin of orbit located on ventral surface of head. Dorsal interorbital distance typically slightly greater than ventral interorbital distance.

Total plates in lateral medial series 23. Dorsal series 19–20 (20); middorsal series 3–4 (3); midventral series, 12–15 (13), with four plates anterior of first plate of ventral series; ventral series 19–20 (20). Second plate of midventral series contacting one plate of medial lateral series.

Abdomen covered by paired series of lateral sickle-shaped plates, with unequal number of plates between left and right series, 3–8; medial series of 1–3 (2) roughly squared plates; medial series occasionally absent, in which case paired series make contact along midline in fully developed individuals; ab- dominal shield fully developed in specimens greater than 25 mm SL. Single anal plate present. Thoracic plates absent. Canal in the preopercle present, semicircular; anteriormost pore opening between ventral canal-bearing plate and fourth infraorbital; posterolateral margin of canal-bearing plate and lateral margin of fourth infraorbital with notch for pore of semicircular canal poorly defined.

Small odontodes evenly distributed on head. Odontodes ventral and dorsal to tip of snout on anterior rostral plate not arranged in well-defined series. No odontode-free discontinuity between ventral and dorsal odontodes; odontodes dorsal to tip of snout small, slightly larger than those on dorsal surface of head. Odontodes on lamina of trunk plates roughly arranged in longitudinal rows; feeble column of marginal odontodes on posterior border of plates. No visible progressive smoothening of plates ontogenetically.

Total vertebrae 27. Premaxillary teeth 10– 28 (19), dentary teeth 12–22 (18). Maxillary barbels short, not reaching to ventral canalbearing plate in adults.

Dorsal-fin origin located at vertical through pelvic-fin origin. Depressed dorsal fin reaching to vertical through posterior half of anal-fin base. Pectoral fin almost reaching to vertical through tip of longest pelvic-fin ray. Extension of serrae along pectoral spine margin, except for short basal segment; serrae of oblique type. Pelvic fin short, unbranched rays slightly shorter than first branched. Depressed fin reaching to plate anterior to anal-fin spine. Caudal-fin margin slightly forked; upper and lower lobes equal. Adipose fin absent.

COLOR IN ALCOHOL: Ground color tan and pale ochre. Melanophores dark brown, irregularly distributed on trunk resulting in an overall marbled pattern. Melanophores on head not uniformly distributed. Melanophores slightly more concentrated between left and right nares and anterior to each naris, on anterior margin of opercle, cleithral posterior process, lateral rostral plates and anterior surface of lip. Narrow line of dark melanophores along margin of tip of snout. In dorsal view, melanophores arranged in illdefined darker clusters (one on predorsal plate, two lighter clusters lateral to dorsal-fin base, two or three posterior to dorsal fin). Midlateral stripe fading toward dorsal surface of trunk and toward caudal fin. Ventral surface of body mostly unpigmented. Three to six dark blotches along dorsal-fin spine, weakly extended over branched rays. Basal triangular dark brown to black spot at base of caudal-fin lower lobe; 3–6 dark blotches along caudal-fin unbranched rays, weakly extended over branched rays.

SEXUAL DIMORPHISM: Male urogenital papilla completely covered by flaplike anus; joined at base. Males with patch of tightly arranged small odontodes oriented as a swirl covering second, third, and fourth plates of ventral series, lateral to urogenital papilla. Males with soft-tissue flap along posterior margin of pelvic spine variably developed; when present, short, restricted to basal onethird to one-half of spine. Female anus tubular, without separate urogenital papilla. In females, size and arrangement of odontodes on plates lateral to anus similar to adjacent plates, without distinct patch of differentially arranged odontodes. Female pelvic spine without flap of soft tissue on posterior surface.

DISTRIBUTION: Tributaries of Río Amazonas between confluence of Ucayali-Marañon rivers and Manaus (fig. 27).

ETYMOLOGY: The specific epithet brevirostratum (Lt. brevis, meaning ‘‘short’’; Lt. rostrum, meaning ‘‘snout’’)is a reference to the short head.

Figures

Fig. 26. Hypoptopoma brevirostratum, holotype, FMNH 105076, 34.0 mm SL, female, in dorsal, lateral, and ventral views.