Hypoptopoma thoracatum Günther, 1868a

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 : 38-43

Hypoptopoma thoracatum Günther, 1868a Figure 2 , table 5

Hypoptopoma thoracatum Günther, 1868a: 477 (original description; Xeberos, Peru).— Günther, 1868b: 234 (descriptions of freshwater fishes from Surinam and Brazil).— Eigenmann and Eigenmann, 1889: 40 (list of catfish species of South America; senior synonym of H. bilobatum and H. joberti ; key).— Eigenmann and Eigenmann, 1890: 388 (list of catfish species of South America).— Boulenger, 1896: 34 (list of fishes from Río Paraguay; key of Hypoptopoma species ).— Regan, 1904: 263 (senior synonym of H. bilobatum ; key to Hypoptopoma species ).— Fowler, 1915: 235, 237 (annotated list of catfish species; assigned to subgenus Hypoptopoma ).— Eigenmann and Allen, 1942: 200 (list of freshwater fishes of Western South America).— Fowler, 1945: 99 (list of freshwater fishes of Peru).— Gosline, 1945: 98 (list of catfish species of South and Central America).— Fowler, 1954: 127 (list of freshwater fishes of Peru).— Boeseman, 1974: 264–266 (list of nominal species of Hypoptopoma ).— Isbrücker, 1980: 87 (list of loricariid species); Ortega and Vari, 1986: 17 (list of fishes of Peru; Carachama).— Eschmeyer and Ferraris, 1998: 1674 (catalog of fishes).— Mojica, 1999: 561 (list of freshwater fishes of Colombia).— Isbrücker, 2002: 28 (list of loricariid species).—Schaefer, 2003: 323 (list of hypoptopomatine species).— Mojica et al., 2005: 201 ( Colombia: occurrence in the Amazon basin, Leticia).—Bogotá-Gregory and Maldonado-Ocampo, 2006: 76 (list of fishes of the Amazon basin in Colombia).— Ferraris, 2007: 250 (list of catfish species).

Hypoptopoma bilobatum Cope, 1870: 566 (original description; Pebas, Peru).— Cope, 1878: 679 (list of freshwater fishes of Peru).— Steindachner, 1882: 7 ( Peru: occurrence at Huallaga).— Isbrücker, 1980: 87 (list of loricariid species).— Ortega and Vari, 1986: 17 (list of fishes of Peru; Carachama).—Schaefer, 2003: 323 (list of hypoptopomatine species).— Ferraris, 2007: 250 (list of catfish species).

Hypoptopoma thoracatus Boulenger, 1895: 527 (misspelling; key to species of Hypoptopoma ).

HOLOTYPE: BMNH 1867-6 :13–38, 76.2 mm SL, Peru, Xeberos.

NON- TYPES: Bolivia, Beni: INHS 37227 (11 ♀ + 2 ³ + 1 juvenile, 19.9–42.4 mm SL) Río Apere / Amazonas dr., Río Chevejecure , 41 km E Estación Biológica del Beni on road to San Ignacio ; ZSM 28426 (1 ♀, 44.7 mm SL) Espiritu, Río Yacuma. Pando: FMNH 107059 (3 ³, 42.1–47.8 mm SL) Río Madeira dr., Río Nareuda , 7 km río arriba de la desembocadura en el Tahuamanu ; FMNH 107060 (19 ♀ + 2 ³, 30.2–42.0 mm SL) Río Madeira dr., Río Manuripi , +/2 12 km río arriba de Puerto Rico ; FMNH 107061 (7 juveniles, 25.0– 29.4 mm SL) Río Madeira dr., lago del campamento, +/2 10 km río arriba de Puerto Rico ; FMNH 107063 (2 ♀ + 1 ³ + 9 juveniles, 30.8–47.2 mm SL) Río Madeira dr., Río Manuripi, +/2 13 km río arriba de Puerto Rico ; FMNH 107064 (3 ♀, 28.0– 33.1 mm SL) Río Madeira dr., Río Manuripi , +/2 13 km río arriba de Puerto Rico ; FMNH 107065 (1 ♀ + 14 juveniles, 25.6–47.1 mm SL) Río Madeira dr., lago s/n, +/2 15 km río arriba de Puerto Rico ; FMNH 107066 (9 juveniles, 29.1–33.4 mm SL) Río Madeira dr., lago s/n ; +/ 2 13 km río arriba de Puerto Rico ; FMNH 107067 (31 ♀ + 2 ³, 29.5– 40.2 mm SL) Río Madeira dr., lago s/n ; +/ 2 12 km río arriba de Puerto Rico ; FMNH 107068 (4 ♀, 32.8–36.6 mm SL) Río Madeira dr., Río Orthon , +/2 2 km río abajo de Puerto Rico ; FMNH 107069 (1 ♀ + 1 ³ + 10 juveniles, 24.1–49.3 mm SL) Río Madeira dr., Río Manuripi ; +/ 2 8 km río arriba de Puerto Rico ; FMNH 107070 (3 ♀, 32.4–34.1 mm SL) Río Madeira dr., Río Manuripi at playa, 5.78 km from camp, 9.23 from Puerto Rico ; FMNH 107071 (54 juveniles, 26.9–31.9 mm SL) Río Madeira dr., lagoon and backwater off Río Manuripi , 1.70 km above Puerto Rico ; FMNH 107072 (4 ♀, 30.8–32.3 mm SL) Río Madeira dr., lagoon on SW side of island 3.47 km up river from Puerto Rico on the Río Manuripi. Brazil, Amazonas: INPA 14036 (8 ♀ + 5 ³, 41.1–47.4 mm SL) Rio Solimões , Paraná do Rei, Ilha do Careiro ; USNM 308312 (1 ♀, 49.9 mm SL) near Manaus , Lago January, Lago Terra Preta ; USNM 308336 (1 ³, 40.3 mm SL) near Manaus , Lago January, Lago Terra Preta ; USNM 316539 (7 ³, 33.3–38.8 mm SL) Rio Purus. Pará: FMNH 59620 (1 ♀, 40.20 mm SL) Santarém. Colombia, Amazonas : CAS 76651 (1 ♀, 46.0 mm SL) Caqueta Dept., Tres Esquinas ; CAS 153141 (6 ♀ + 1 ³, 41.8– 73.1 mm SL) Caqueta Dept., Río Orteguaza, tributary of Río Caqueta, within 2 mi. of Tres Esquinas ; SU 50479 (4 ♀ + 2 ³, 36.9–

TABLE 5 Morphometric and Meristic Data for Hypoptopoma thoracatum Syntype of H. bilobatum: ANSP 8280. Nontypes: AMNH 78033, 78099; CAS 153141; FMNH 101544, 107058, 107059, 107060, 107063, 107069; INHS 101389; LACM 38608; MUSM 1845, 4413; SIUC 29199; SU 36218.

43.9 mm SL) Caqueta Dept., vecinity of Tres Esquinas, Río Orteguaza near juncture with Río Caqueta ; USNM 360864 (1 ♀ + 1 ³, 68.8–75.8 mm SL) Leticia. Ecuador, Napo: FMNH 101544 (3 ³, 53.2–62.2 mm SL) Tributary to Rio Tarapuy. Peru, Loreto: AMNH 78033 (1 ♀, 55.7 mm SL) Río Tahuayo at Huasi Villeage ; AMNH 78099 (9 ♀ + 1 ³, 1 cs, 45.8–76.9 mm SL) Río Yarapa , tributary of Río Ucayali, several sites along a 10 km stretch of river ; AMNH 218005 (1 ♀, 66.4 mm SL) Iquitos, Río Itaya ; ANSP 8280 /81 (syntypes of Hypoptopoma bilobatum ) (2, unsexed, 59.5–74.9 mm SL) Pebas ; CAS 59599 (3 ♀, 43.03–48.78 mm SL) mouth of Río Pacaya ; CAS 134256 (1 ♀, 46.3 mm SL) Río Ampiyacu ; CAS 136219 (1 ♀, 56.5 mm SL) Caño del Chancho , near Pebas ; INHS 53870 (8 ♀, 33.0– 53.7 mm SL) Río Itaya, Ullpa caño, SE of Belem ( Iquitos ), near confluence with Moena caño ; INHS 101388 (1 ♀ + 1 ³, 52.3–64.8 mm SL) Río Yanashi , Yanashi, 69.8 mi E Iquitos ; INHS 101389 (8 ♀ + 2 ³, 2 cs, 32.1–73.1 mm SL) Río Orosa , mouth of Tonche Caño, Madre Selva II field station 69.4 mi. E Iquitos ; INHS 101391 (1 ♀, 68.6 mm SL) Quebrada Mazama, Río Itaya dr., ca. 1 km upstream from confluence with Río Itaya, S of Belem ( Iquitos ) ; MUSM 4413 (3 ♀, 49.7–54.5 mm SL) Alto Amazonas, Yurimaguas, Río Shanusi ; MUSM 6515 (1♀, 64.3) Maynas, Puesto de Vigilancia Arcadia, Río Napo, Cocha de Conchas ; NRM 17992 (3 ♀, 45.8– 48.7 mm SL) Río Samiria drainage, Atún caño ; NRM 57232 (1 ♀ + 1 ³, 54.2–60.9 mm SL) Rio Tahuayo dr., caño Huayti ; SIUC 29199 (1 ♀ + 1 ³, 68.3–78.3 mm SL) Maynas, Río Itaya , upriver of Belén, approx. 4.5 km ; SIUC 29316 (1 ♀, 66.6 mm SL) Río Napo, Mazan, 33.3 km from center of Iquitos ; SIUC 29782 (1, 54.6 mm SL) Maynas, Río Itaya, 11 km from Iquitos center ; SIUC 67366 (5 ♀, 44.6–53.1 mm SL) Maynas, Río Itaya and Quebrada Mazana, 11 km from Iquitos center ; SU 36218 (2 ♀, 57.4–67.6 mm SL) Río Amazonas, Caño del Chancho , near Pebas. Ucayali: LACM 38608 (3 unsexed, 47.0– 66.6 mm SL) Central Ucayali, brook between Lake Cocha and Lake Yarina ; MHNG 2407.98 (1 ♀, 35.3 mm SL) Pucallpa, Tapistica Alejandria ; MHNG 2409.26 (1 ♀, 50.6 mm SL) Pucallpa, Masisea, Río Ucayali ; MHNG 2409.27 (1 ♀, 41.4 mm SL) Pucallpa, Masisea, Río Ucayali ; MHNG 2618.84 (1 ³, 55.07 mm SL) Río Puntichao and Río Chicosa , two tributaries entering Ucayali River near Chicosa ; MHNG 2708.059 (2 ♀, 37.4–38.6 mm SL) Yarina Cocha, an oxbow lake near Pucallpa ; MUSM 32157 (3 ♀ + 2 ³, 1 cs, 43.3–59.6 mm SL) Coronel Portillo, Pucallpa, Tapistica Alejandria ; MUSM 32158 (2 ♀, 47.2–50.1 mm SL) Coronel Portillo, Pucallpa, Río Ucayali, Cocha Tacshitea ; NRM 17987 (2 ♀, 64.4–64.6 mm SL) Río Ucayali dr., Yarinacocha, caño to Paca Cocha .

DIAGNOSIS: Hypoptopoma thoracatum is distinguished from all congeners by the presence of an elongated spot of black melanophores along the caudal-fin branched rays, not distinctly connected to the lanceolate plates at the base of the fin; spot extended over a larger number of lower-lobe rays than upper-lobe rays and along one-half to more than two-thirds of the ray length (figs. 17A, 24).

DESCRIPTION: Morphometric and meristic data presented in table 5. Body moderately robust. Dorsal profile of head and body straight from tip of snout to dorsal-fin origin, slightly elevated at predorsal plates; straight from dorsal-fin origin to anteriormost caudal-fin procurrent ray. Head moderately depressed and wide. Lateral process of lateral ethmoid bone visible dorsally. Snout slightly rounded in dorsal view; dorsally smoothly rounded, slightly concave anterior to naris. Posterior surface of bony pit of nasal organ gradually inclined. Body cross section between pectoral- and pelvic-fin origins horizontally ovoid, vertically ovoid to progressively rounded posterior to dorsal fin, progressively compressed posterior to adipose-fin base.

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

Total plates in lateral medial series 22–24 (23). Dorsal series 19–21 (20); middorsal series 3–4 (4); midventral series 13–14 (13), with 4–5 (4) plates anterior of first plate of ventral series; ventral series 19–21 (20). Second plate of midventral series contacting a single 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, 5–11 each; medial series of 5–13 (8) roughly squared plates; anterior azygous plate absent; occasionally, transversal series of more than three small plates posterior of coracoids, not aligned with main three longitudinal series. Single anal plate present. Thoracic plates absent. Preopercular canal absent. Posterolateral margin of canal-bearing plate and lateral margin of fourth infraorbital smooth; pore between canalbearing ventral plate and fourth infraorbital absent.

Small odontodes evenly distributed on head. Odontodes ventral and dorsal to tip of snout not arranged in aligned series. No odontode-free discontinuity between ventral and dorsal odontodes; odontodes dorsal to tip of snout slightly larger than those on head. Lamina of trunk plates bearing longitudinal rows of odontodes, and becoming progressively smoother ontogenetically; distinct column of marginal odontodes on posterior plate border in mature adults.

Total vertebrae 27. Premaxillary teeth 19– 34 (24); dentary teeth 14–28 (20). Maxillary barbels short, almost reaching to or slightly surpassing anterior margin of ventral canalbearing plate in adults.

Dorsal-fin origin located slightly posterior of vertical through pelvic-fin origin. Depressed dorsal fin reaching to vertical through posterior half of anal-fin base. Pectoral fin reaching to vertical through midpoint of pelvic-fin base. Extension of serrae along pectoral spine margin, except for short basal segment; serrae of oblique type. Pelvic fin short, two longest branched rays slightly longer than spine. Depressed fin reaching to plate anterior to anal-fin spine. Caudal-fin margin forked; upper and lower lobes equal and not extremely elongate. Adipose fin present.

COLOR IN ALCOHOL: Ground color tan and pale ochre. Melanophores light to dark brown, clustered resulting in mottled appearance. Melanophores slightly more concentrated dorsally on head, narrow area among compound pterotic, cleithral process, and opercle, at base of dorsal fin, anterior surface of lip, and anterior half of branchiostegal membrane. Head uniformly tan dorsally, except for darker area over brain. Deep-lying melanophores arranged in narrow transverse bands posterior to dorsal-fin base, noncoincident with posterior margin of plates. Midlateral stripe situated mostly along medial series of trunk plates (fig. 24). Ventral surface of body mostly unpigmented, except for scattered melanophores on posterior portion of trunk, soft tissue along base of pectoral and anal fins, anterolateral margin of cleithrum and posterior tip of cleithral process, ventral canal-bearing plates, and lateral portions of lateral series of abdominal plates. Dorsal and anal fins with dark brown bands. Caudal-fin bars variable defined. Presence of an elongated spot of black melanophores along caudal-fin branched rays, not distinctly connected to lanceolate plates at base of fin; spot typically extending over larger number of lower-lobe rays than upper-lobe rays and along one-half to more than two-thirds of ray length (figs. 17A, 24). Tip of upper and lower lobes variably dark.

SEXUAL DIMORPHISM: Male urogenital papilla short and slender, covered by anterior flaplike anus. Males with patch of tightly arranged small odontodes oriented as a swirl, variably covering first to fourth plates of ventral series, lateral to urogenital papilla. Males with flaplike anus along posterior margin of pelvic spine variably developed; when present, short, weakly developed, restricted to basal one-third to 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.

TAXONOMIC REMARKS: The genus Hypoptopoma was established by Günther (1868a) for his new species Hypoptopoma thoracatum (fig. 2) on the basis of one specimen collected by Barlett at Xeberos ( Peru, upper Amazon). He distinguished the new taxon from the loricariid Plecostomus [5 Hypostomus ] by the ‘‘peculiar formation of the head, depressed, spatulate, the eyes being on the lateral edges of the head.’’ During 1868, Günther published two papers in which he provided a taxonomic account of the new genus and species. In the first publication, Günther (1868a) provided a brief diagnosis for the genus and the new species H. thoracatum that only specified counts for fin rays and lateral-line plates. A subsequent expanded description of H. thoracatum was published later during the same year ( Günther, 1868b). Therefore, H. thoracatum is considered the type species of the genus. Regarding Hypoptopoma bilobatum, Cope (1870) estab- lished the new species on the basis of one specimen collected in 1869 by Hauxwell in Pebas, Ecuador (a region which is now part of Peru), but failed to provide a justification for the proposition of a new species distinguishable from H. thoracatum Günther 1868a , the only species described for the genus at the time. Ultimately, Eigenmann and Eigenmann (1889) placed Cope’s species as junior synonym of H. thoracatum , a designation that has been maintained in the literature almost invariably since then, and confirmed herein.

DISTRIBUTION: Ríos Caqueta, Mamore´, Purus, and Ucayali of Western Amazon (fig. 25).

Figures

Fig. 2. Holotype and jar label of the type species of the genus Hypoptopoma, H. thoracatum, BMNH 1867.6.13:38.