Batrochoglanis labrosus, Shibatta, 2024

Shibatta, Oscar Akio, 2024, New species of Batrochoglanis Gill (Siluriformes: Pseudopimelodidae) from the Capim River basin, State of Pará, Brazil, Zootaxa 5463 (2), pp. 273-282 : 274-279

Batrochoglanis labrosus new species urn:lsid:zoobank.org:act:D5A553EC-CCF6-4821-BC2C-62B12207F6AC

( Figs. 1–4 , Table 1 )

Holotype. MZUSP 129875 (ex-MZUSP 23864), 87.8 mm SL, Brasil. Pará , Igarapé Caranandéua , Rio Capim, 16 Aug 1970, Expedições Permanentes na Amazônia ( EPA).

Paratypes. Brasil. Pará : MZUSP 22269 , 6 , 30.0- 41.6 mm SL, Belém-Brasília Road km 97, Igarapé Pacuí, 15 Aug to 20 Oct 1959, Department of Zoology Expedition (Exp. DZ). MZUSP 23830 , 1 , 15.8 mm SL, Igarapé JariMirim, Rio Capim, 12 Aug 1970 ( EPA). MZUSP 23862 , 8 , 20.4–30.05 mm SL, Igarapé Caranandéua , Rio Capim, 16 Aug 1970 ( EPA). MZUSP 23864 , 13 , 65.4–110.2 mm SL, same data as holotype. MZUSP 23884 , 1 , 28.2 mm SL, Lago Maria Preta , Rio Capim, 18 Aug 1970 ( EPA). MZUSP 23939 , 1 , 36.0 mm SL, Igarapé Canteiro, perto de Vila Santana, Rio Capim , 22 Aug 1970 ( EPA) .

Diagnosis. Batrochoglanis labrosus is distinguished from congeners by inferior mandible stout, exceptionally developed lips forming wide fold (vs. moderately developed lips; fig. 2); by the unique color pattern, constituted by a dark brown head (vs. mottled in B. villosus and B. melanurus ), a broad dark brown band on the trunk to the posterior third of adipose fin, followed by a second dark brown band on the caudal peduncle (vs. mottled in B. villosus and B. melanurus ; completely dark brown or black with small light brown areas in B. raninus , B. castaneus , and B. transmontanus ; or irregularly shaped dark brown band in B. acanthochiroides ), dark brown pelvic fin (vs. mottled in B. villosus ), and the caudal fin with dark brown blotches forming an irregular stripe in the posterior region (vs. mottled in B. villosus , completely dark brown in B. melanurus , or with a well-defined dark brown or black stripe in B. raninus , B. castaneus , B. transmontanus , and B. acanthochiroides ).

Description. Body proportions in Table 1 . Dorsal profile slightly ascending from snout tip to posterior nostril; pronounced ascension from posterior nostril up to nape; somewhat concave at nape; convex until dorsal-fin origin; dorsal-fin origin up to adipose-fin insertion slightly declined; caudal peduncle concave. Head ventral profile convex; belly and pelvic to anal fins almost straight; pelvic fin to anal fin convex; caudal peduncle concave. Head large, wider than long; trapezoidal profile in dorsal view; adductor muscle well developed; dorsolateral profile convex. Mouth terminal; inferior mandible stout; lips lateral fold well developed. Body anterior region depressed from snout tip to dorsal-fin origin, compressed posteriorly to caudal fin. Opercular opening wide; gill rakers aciculiform; 9- 12* (2,1,9* (2), 2,1,7 (16), 2,1,8 (3), 2,1,6 (3), 3,1,7 (1), 3,1,8 (4)). Opercular posterior margin surpassing vertical through pectoral-fin insertion; opercular membrane well developed. Eyes relatively small, covered with skin, dorsal position. Anterior nostril tubular on dorsal lips. Posterior nostril closer to eye than anterior nostril; triangular small fold anteriorly. Maxillary barbel reaches vertical through dorsal-fin origin, frequently not surpassing opercular membrane. External mental barbel when adpressed reaching pectoral fin origin. Frontal fontanel extending slightly beyond line through orbits posterior margins. Dorsal fin trapezoidal, located before middle body; posterior margin rounded; when adpressed, not reaching or slightly contacting adipose-fin origin; I,6 rays. Dorsal-fin spine with tiny serrae anteriorly.Adipose fin elongate, with posterior end free and angled. Pectoral-fin triangular; not reaching pelvic fin when adpressed; spine serrated on both sides; I,6 rays. Pelvic fin triangular; posterior margin rounded; origin at vertical through last ray base, slightly before middle body; reaching anal-fin origin when adpressed; I,5 rays. Anal fin rounded; base length slightly same as adipose-fin base; ii–iv, 6–9 (iii,6 (1), iv,6 (1), ii,7 (3), iii,7 (10), ii,8* (6), iii,8 (5), iii,9 (1)) rays. Caudal fin emarginate, dorsal lobe longer than ventral lobe; 11(1), 12(8),13(8)* principal rays. Lateral line incomplete, slightly surpassing vertical through adipose-fin insertion. Cephalic laterosensory system pores: infraorbitals i1–i6; supraorbitals s1, s2, s3, s6 and s8, preoperculomandibular pm1–pm9, postorbital pm11+po1, po2. Posterior cleithral process sharp-pointed, short, almost covered by opercular membrane. Axillary pore absent.

Coloration of adults in alcohol. Ground color light brown. Head dorsal and lateral region dark brown specked with darker points. Head ventral region whitish. Nape and opercular membrane with well-defined pale brown band, extending along dorsal region between pectoral fins. Maxillary barbel light brown with dark-brown spots; base darker than tip. Flanks between posterior nape to adipose fin posterior third dark brown speckled with darker points. Flanks near dorsal fin with two light brown spots in juvenile; not evident in bigger individuals (fig. 3). Belly whitish with dark brown spots. Caudal peduncle pale brown stripe on vertical through adipose fin posterior third to insertion; dark brown band posteriorly, until caudal-fin base. Dorsal fin dark brown, with medial light stripe from second to last rays; dorsal margin whitish. Adipose fin dark brown; anterior portion with or without light brown spot; posterior region with pale brown blotch ventrally united with caudal peduncle light brown stripe. Pectoral fin dark brown; first ray (spine) base and tip whitish. Pelvic fin dark brown with numerous spots; rays one to four tips whitish; base with light brown stripe. Anal fin hyaline, base dark brown, margin with arched line of dark brown spots. Caudal fin hyaline with dark brown rounded spots; posterior third with dark brown spots forming an irregular stripe.

Coloration of juveniles in alcohol. Background light brown ( Fig. 4 ). Head brown dorsally and laterally. Nape region, posterior operculum, maxillary, inner, and outer mental barbels light brown background color. Nape and opercular membrane with well-defined pale brown band, extending along dorsal region between pectoral fins, wider in juvenile (up to 42 mm SL). Trunk, partial caudal, dark brown; background light patch near dorsal and pelvic fins. Saddle-shaped light brown spots on caudal peduncle dorsal and ventral regions. Caudal peduncle bar dark brown, light brown spot dorsally and ventrally. Dorsal fin dark brown stripe from base to near upper margin; dorsal edge with clear stripe. Pectoral fin dark brown; first ray point whitish. Pelvic fin dark brown; margin whitish. Adipose fin anterior and posterior regions whitish; dark brown spot in the middle. Anal fin hyaline; base with dark brown patch; hind third with or without dark brown spots line. Caudal fin hyaline, posterior third with or without dark brown spots.

Distribution. The species is known only from the Capim River basin, Pará, Brazil.

Etymology. The species name labrosus (Latin labrum = lip and osus = fullness or abundance) is an adjective related to the conspicuously developed lips in the species.

Principal Components Analysis. The principal components analysis showed morphometric similarity between B. labrosus , B. melanurus , and B. villosus ( B. villosus group). Still, it differentiated these species from the morphometric more similar B. transmontanus and B. acanthochiroides ( Fig. 5 ). The discrimination occurred in the third axis, which retained 0.43% of the variance of the data. The variables with the highest loadings in B. villosus group were the longer adipose-fin base length, eye diameter, maxillary barbel length, head depth, mouth width (positive loadings), shorter pelvic fin to anal fin, and pectoral-fin spine length (negative loadings) ( Table 2 ).

Figures

FIGURE 1. Batrochoglanis labrosus, holotype, MZUSP 129875 (ex-MZUSP 23864), 87.8 mm SL, Igarapé Caranandéua, rio Capim, Pará, Brasil.

FIGURE 2. Head photographs showing the lips in A) Batrochoglanis labrosus (MZUSP 23864, 96.5 mm SL) and B. villosus (ANSP 135903, 91.4 mm SL).

FIGURE 3. Coloration of Batrochoglanis labrosus largest specimen (MZUSP 23864, 110.2 mm SL).

FIGURE 4. Juvenile of Batrochoglanis labrosus, paratype, MZUSP 22269, 41.2 mm SL, Pará, Brazil.

FIGURE 5. Scatterplot of individual scores of combined samples of B. acanthochiroides (n = 8), B. labrosus (n = 20), B. melanurus (n = 5), B. transmontanus (n = 5), and B. villosus (n= 10) in the second and third axis of Principal Components Analysis.