Hypoptopoma bianale, Aquino, Adriana E., 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 : 57-60

Hypoptopoma bianale , new species Figure 31 , table 10

HOLOTYPE: FMNH 105077 (♀, 53.7 mm SL) Colombia: Amazonas, Amazon River at 2 to 3 miles upstream from Leticia; collected by Navarro et al., 13 November 1973.

PARATYPES (all material collected with holotype): FMNH 117745 (7 ♀ + 3 ³, 2 cs, 37.2–47.9 mm SL) ; AMNH 243576 (1 ♀ + 1 ³, 46.1–47.3 mm SL) .

NON- TYPES: PERU, Loreto: MZUSP 36208 (1 ♀, 43.0 mm SL) Río Ucayali, Sgto. Lores ; SIUC 28113 (1 ♀, 39.0 mm SL) Río Napo, confluence with Río Mazán, ca. 2–3 km N (town of) Mazán ; SU 33272 (1 ³, 42.6 mm SL) Río Ampiyacu. Ucayali: MHNG 2390.25 (1 ♀, 44.5 mm SL) Pucallpa, Río Ucayali, San Antonio ; MZUSP 36206 (1 ³, 43.2 mm SL) Pucallpa , Río Ucayali ; MZUSP 36207 (1 ♀, 42.03 mm SL) Pucallpa, Río Ucayali, Laguna Yarinacocha. BRAZIL, Amazonas: MZUSP 27624 (1 ♀, 41.2 mm SL) Costa Japao, Baixao Rio Japurá , Mun. de Tefe´ ; MZUSP 36211 (4 ♀, 41.0– 51.8 mm SL) Rio Solimões, prox. I. Bururuá acima do boca do Jutaí .

DIAGNOSIS: Hypoptopoma bianale is distinguished from all congeners by presence of two medial anal plates (vs. single medial anal plate in all other species of Hypoptopoma ) (fig. 9C).

DESCRIPTION: Morphometric and meristic data presented in table 10. Body robust, stocky, greatest body depth at dorsal-fin origin, least depth at caudal peduncle. Dorsal profile of head and body straight from tip of snout to posterior tip of supraoccipital, smoothly convex at level of predorsal plates. Dorsal profile of trunk straight from dorsalfin origin to caudal procurrent rays. Ventral profile of head and abdomen straight to slightly convex from snout tip to caudal-fin procurrent rays (not apparent in lateral view of head profile). Head moderately depressed, slightly acute, smoothly concave anterior to naris. Posterior surface of bony pit of nasal organ gradually inclined. Lateral process of lateral ethmoid bone slightly visible in dorsal view of head. Trunk cross section ovoid to progressively compressed posterior to dorsal fin.

Eyes moderately large, positioned slightly closer to posterior tip of compound pterotic than to tip of snout. Ventral margin of orbit close to ventral margin of head. Dorsal interorbital distance roughly equal to ventral interorbital distance.

Total plates in medial series 22. Dorsal series plates 19; middorsal series plates 3–4 (4); midventral series plates 12–13 (13), three plates anterior to first ventral series plate; ventral series plates 19. Second plate of midventral series contacting two plates of medial series.

Abdomen covered by paired series of lateral sickle-shaped plates, with unequal number of plates between left and right series, 4–6; anterior azygous plate present; lateral series make contact along midline in fully developed individuals. Presence of two medial anal plates positioned along longitudinal axis of body, between pelvic fins laterally, abdominal plates anteriorly,

TABLE 10 Morphometric and Meristic Data of Hypoptopoma bianale Holotype: FMNH 105177 . Paratypes: FMNH 117745 ; AMNH 243576 . Nontypes: MNHG 2390.25 ; MZUSP 27624 , 36203 , 36206 , 36207 , 36208 , 36211 ; SU 33272 .

and anus posteriorly; anterior plate larger than posterior plate (fig. 9C). Thoracic plates present, 4–5. Canal in preopercle present, semicircular; anteriormost pore located between ventral canal-bearing plate and fourth infraorbital, framed by notch at posterolateral margin of canal-bearing plate and lateral margin of fourth infraorbital.

Small odontodes evenly distributed on head. Odontodes on rostral margin of snout enlarged and arranged in irregular lines, without odontode-free discontinuity between dorsal and ventral margins. Lamina of trunk plates with odontodes arranged in longitudinal rows; plates progressively smoother in ontogeny; marginal odontodes present in mature adults. Anterior margin of pectoralfin spine and ventral surface of pelvic-fin spine with enlarged odontodes.

Total vertebrae 26. Premaxillary teeth 21– 29 (25), dentary teeth 20–27 (23). Maxillary barbels extending slightly beyond anterior margin of ventral canal-bearing plate.

Dorsal-fin origin located at vertical through pelvic-fin origin; depressed dorsal fin reaching almost to vertical through posterior tip of anal fin. Pectoral fin reaching to vertical through posterior tip of pelvic fin. Pectoral spine serrae along entire posterior margin, except for short basal segment; individual serrae oriented oblique to spine shaft. Pelvic fin short, unbranched and first branched rays equal in length; when depressed reaching to plate anterior to anal-fin spine. Caudal-fin margin concave. Adipose fin absent.

COLOR IN ALCOHOL: Overall body pigmentation relatively uniform, ground color tan to pale ochre. Melanophores variably light brown, slightly more concentrated along base of plates, dorsal portions of head, lateral border of compound pterotic, cleithral process, opercle, and base of dorsal fin. No lateral stripe on trunk. Ventral surface of body mostly unpigmented. Scattered dark melanophores present on anterior surface of lip. Fins with pale brown bands (dorsal fin 4– 6; caudal fin 4–5). Triangular spot of dark brown melanophores at base of caudal-fin branched rays, mostly extended over basal plates and lower lobe, progressively widening toward lower marginal ray; caudal-fin bars mainly visible on marginal rays and outer most branched rays.

SEXUAL DIMORPHISM: Male urogenital papilla short, half-length of flaplike anus, which totally covers and joins base of papilla. Males with patch of tightly arranged small odontodes on second through fourth plates of ventral series, lateral to urogenital papilla. 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.

DISTRIBUTION: Rio Solimões in Brazil and Río Ucayali in Peru (fig. 32).

ETYMOLOGY: The specific epithet bianale is a reference to the presence of two anal plates (Lt. bi, meaning ‘‘two’’; Lt. analis, from anal (adaptation from modern Latin; Oxford English Dictionary: ‘‘Of or pertaining to the anus, or excretory opening’’).

Figures

Fig. 31. Hypoptopoma bianale, holotype, FMNH 105077, 53.7 mm SL female, in dorsal, lateral, and ventral views.