Peckoltia oligospila ( Günther 1864 )

Armbruster, Jonathan W., 2008, The genus Peckoltia with the description of two new species and a reanalysis of the phylogeny of the genera of the Hypostominae (Siluriformes: Loricariidae), Zootaxa 1822 (1), pp. 1-76 : 34-37

Peckoltia oligospila ( Günther 1864)

( Fig. 18–19 )

Chaetostomus oligospilus Günther, 1864: 244 . Type locality: River Capin [ Brazil]. Holotype: BMNH 1849.11.8, illustrated in Regan (1904b: 232, pl. 12 fig. 1).

Material Examined: All Collections BRAZIL, Pará, Rio Tocantins – Atlantic Ocean drainage: BMNH 1849.11.8, Holotype, 1, 87.2, Rio Capim ; INPA 6321 , 1 , 148.6 , Rio Tocantins, Igarapé Jatobal , Equipe Ictilogia do INPA, 17 July 1981; MCP 14535, 5 , 54.3 –70.0, Rio Tocantins in the city of Cametá, M. T. C. Lacerda, 1988; MCP 21967, 1 , 101.7 , Rio Guamá in Urucuritéua on the road between São Miguel do Guamá and Ourém, Rio Capim basin, 01°35’28”S, 047°20’18”W, R. Reis, J. P. Silva, E. Pereira, J. Montoya, 22 July 1998; MCP 21970, Rio Jauara on the Belém / Brasília Road ( BR 010 ) between Mãe do Rio and Irituia, Rio Capim basin, 01°55’29”S, 047°31’21”W, R. Reis, J. P. Silva, E. Pereira, J. Montoya, 19 July 1998; MCP 21971, 5 , 93.4 – 104.2 , Rio Guamá near Ourém, Rio Capim basin, 01°35’28”S, 047°20’18”W; MCZ 62116, 1 , 136.1 , Río Apeu at Boa Vista, Rio Capim basin, 01°18’S, 047°59’W, N.A. Menezes, July 1965; MZUSP 23872 , 1 , 83.6 , Rio Capim , close to Caranan déua, EPA, 16–17 August 1970; MZUSP 53398 , 1 , 135.7 , Igarapé Apeú, Boa Vista, 01°18’S, 047°58’W, P.E. Vanzolini, 3–4 February 1964; NMW 48065, 1 , 111.8 , Pará, Brasilien Expedition, 1903.

Diagnosis: Peckoltia oligospila can be identified from all other Peckoltia except P. bachi and some P. furcata by having spots on the body and the saddles faint; from P. bachi by having narrow pelvic-fin spines (vs. wide), the eye high on the head (vs. low), and by having the spots distinctly round (vs. appearing more as a mottling); and from P. furcata by having spots on the abdomen of larger juveniles and adults (vs. spots on abdomen always absent) and by having the spots separate in the caudal fin (vs. combining to form bands). Peckoltia lineola also has spots on the head. Peckoltia oligospila can be further separated from P. lineola by having spots in all fins (vs. bands in all fins) and by having none of the spots on the head combining to form vermiculations.

Description. Morphometrics in Table 4, counts based on 17 individuals unless otherwise stated. Largest specimen examined 148.6 mm SL. Body stout and fairly wide. Head gently sloped to parieto-supraoccipital. Parieto-supraoccipital with tall crest. Parieto-supraoccipital crest raised well above nuchal region. Nuchal region rises slightly to nuchal plate. Dorsal profile sloped ventrally to dorsal procurrent caudal-fin spines, then rising rapidly to caudal fin. Ventral profile flat to ventral procurrent caudal-fin spines and then sloping ventrally to caudal fin. Supraorbital ridge rounded, contiguous, but slightly offset medially from rounded ridge proceeding from anterior margin of orbit to anterolateral corner of anterior nare. Head contours smooth except parieto-supraoccipital crest. Eye medium-sized.

Keels absent. Mid-ventral plates bent at their midline above pectoral fin to form ridge. Dorsal plates bent dorsally below dorsal fin to form ridges that converge at preadipose plate, dorsal surface flat between ridges. Five rows of plates on caudal peduncle. Abdomen largely naked with a column of plates below pectoral girdle, rows of plates laterally, a patch of plates in front of the anus, and occasionally a small patch of plates medially just posterior to pectoral girdle. First anal-fin pterygiophore exposed to form a platelike structure. A pair of lateral plates converging at midline between anus and exposed first anal-fin pterygiophore. 24–26 (mode 26) plates in the median series.

Frontal, infraorbitals, nasal, compound pterotic, sphenotic, and parieto-supraoccipital, supporting odontodes; opercle supporting odontodes in juveniles but not in adults, posterodorsal corner of opercle covered by one or two plates in adults. Odontodes on lateral plates not enlarged to form keels. Hypertrophied cheek odontodes 13–50 (N=16), longest almost reaching first mid-ventral plate in adults. Cheek plates evertible to approximately 90° from head. Odontodes on tip of pectoral-fin spine slightly hypertrophied.

Dorsal fin short, not reaching preadipose plate fin when adpressed; dorsal-fin spine same length as proceeding rays making edge straight. Dorsal-fin spinelet V -shaped, dorsal-fin spine lock functional. Dorsal fin II,7. Adipose fin with one preadipose plate and fairly long spine. Caudal fin forked, lower lobe longer than upper, I,14,I with three to five (mode five) dorsal procurrent caudal-fin rays and two to four (mode four) ventral procurrent-fin rays. Anal fin short with unbranched ray weak and about same length of first branched ray. Anal fin I,4, Pectoral-fin spine reaching just beyond pelvic fin when adpressed ventral to pelvic fin. Pectoral fin I,6. Pelvic fin reaching to posterior insertion of anal-fin when adpressed. Pelvic fin I,5.

Iris operculum present. Flap between anterior and posterior nares short. Lips wide, fairly thin. Upper lip with small, round papillae. Lower lip with small papillae anteriorly and posteriorly, becoming larger medially. Maxillary barbel short, maximally reaching base of evertible cheek plates. Buccal papilla small. Jaws narrow, dentaries forming very acute angle, premaxillaries forming gentle arc less than 135°. Teeth with small, moderately wide cusps, lateral cusp approximately half length of medial cusp, stalk of tooth long; eight to 25 dentary teeth (mode 15), 16–30 premaxillary teeth (mode 20).

Color: Base tan with brown markings. Head with small to medium faint spots slowly becoming larger posteriorly, none of the spots intense. Body with four faint dorsal saddles, the first below the middle rays of the dorsal fin, the second below the posterior rays of the dorsal fin and slightly posterior, the third below the adipose fin and slightly anterior, and the fourth at the end of the caudal peduncle. The first two saddles combine midbody or may fuse completely. Dorsal fin with very large, round spots not arranged in distinct rows. Spots in other fins arranged roughly into rows, but usually not fusing to form bands. In all fins, the light inter- spaces are as wide or wider than the spots. Abdomen usually with medium spots. Ventral surface of caudal peduncle with a single, medial row of spots. Juveniles with much larger spots that contrast much better with lighter areas, no spots on abdomen.

Sexual Dimorphism: None observed, but even on the specimens available, the odontodes on pectoral-fin spine noticeably larger.

Range. Known from the Rios Tocantins and Capim drainages of eastern Brazil ( Fig. 5 ).

Figures

FIGURE 5. Distribution of Peckoltia bachi (circles) and P. oligospila (diamonds). Open symbols are type localities. Symbols may represent more than one locality.

FIGURE 18. Lateral view of holotype of Chaetostomus oligospilus, BMNH 1849.11.8, 87.2 mm SL. Photograph by J.W. Armbruster.

FIGURE 19. Dorsal, lateral, and ventral views of Peckoltia oligospila, MCZ 62116, 136.1 mm SL. Photographs by J.W. Armbruster.