Tatia melanoleuca, Vari & Calegari, 2014

Vari, Richard P. & Calegari, Bárbara B., 2014, New species of the catfish genus Tatia (Siluriformes: Auchenipteridae) from the rio Teles Pires, upper rio Tapajós basin, Brazil, Neotropical Ichthyology 12 (4), pp. 667-674 : 668-672

Tatia melanoleuca new species

Figs. 1-3

Holotype. MZUSP 114670 , 32.4 mm SL, Brazil, along border between Pará and Mato Grosso states, Jacareacanga, close to Sete Quedas rapids, rio Teles Pires , tributary to upper rio Tapajós basin, 9°20’38”S 56°46’42”W, 6 Oct 2008, L. M. Sousa & A. L. Netto-Ferreira.

Paratypes. MZUSP 99944 , 2 , 21.7 - 24.6 mm SL; collected with holotype .

Diagnosis. Tatia melanoleuca can be readily distinguished from all congeners other than T. carolae and T. musaica by the strongly contrasting, dark coloration on the dorsal and to varying degrees lateral and ventrolateral portions of the body that is distinctly demarcated from the lightly colored regions that are translucent in life on the remainder of the body (vs. a variety of alternative coloration patterns in congeners, none of which is comparable to this pigmentation pattern; see illustrations in Royero, 1992: fig. 1; Sarmento-Soares & Martins-Pinheiro, 2008; Pavanelli & Bifi, 2009: fig. 1; Vari & Ferraris, 2013: figs. 1-2). Tatia melanoleuca is distinguished from T. musaica and T. carolae by the absence of dark pigmentation on the lower lobe of the caudal fin (vs. a bilobed pattern of dark pigmentation in that region in T. carolae , or an extension of the dark body pigmentation onto the basal portions of the lobe in T. musaica ) and the possession of 34 vertebrae (vs. 35 or 36 in T. carolae and 35 in T. musaica ). Tatia melanoleuca additionally differs from T. carolae in the dark pigmentation that is uniformly continuous across the portion of the lateral line on the caudal peduncle (vs. with the area bordering the lateral line unpigmented and forming distinct, narrow, posteriorly dorsally angling white stripe within the dark pigmentation on the caudal peduncle), the lack of dark pigmentation on the upper lobe of the caudal fin or with such pigmentation barely extending onto the lobe (vs. a bilobed pattern of dark pigmentation extending onto the lobe in that region), the narrower interorbital width (42.0-42.9% vs. 51.8-62.4% HL), shallower snout depth (34.5-38.5% vs. 43.4-47.5% HL), shorter posterior internarial distance (26.0-29.8% vs. 33.7-38.8% HL) and shorter caudal-peduncle length (18.8-19.5% vs. 22.5- 25.3% SL). Tatia melanoleuca is further distinguished from T. musaica in the presence of an unpigmented region anterodorsal of the orbits either in the form of a rounded spot or a broad median band extending anteriorly to the upper lip (vs. with solid dark pigmentation in that region), the unpigmented dorsal-fin spine (vs. a dusky spine), the lack of dark pigmentation on the dorsal surface of the pectoral-fin spine other than basally (vs. dusky pigmentation extending at least one-half the length of the spine), the location of dark pigmentation on the body other than on the caudal-peduncle dorsal to the horizontal through the middle of the orbit (vs. dark pigmentation broadly extending ventral of that line and reaching to the ventral midline anterior to the anal-fin base), the deeper overall body as reflected in the greatest body depth (23.4-25.6% vs. 17.9-21.8% SL) and deeper caudal-peduncle depth (13.9-14.5% vs. 9.6-12.0% SL).

Description. Morphometric data presented in Table 1. Body depth approximately constant between dorsal- and anal-fin origins and slightly less than HL. Body approximately cylindrical from rear of head through abdomen and increasingly compressed towards caudal fin. Body width greatest at pectoral-fin origin; width slightly less than body depth at that point and tapering progressively towards caudal peduncle. Lateral line midlateral, complete and extending onto, and curving dorsally on caudal peduncle but falling short of posterior limit of hypural plate. Anus situated slightly anterior of anal-fin base. Vertebrae 34 (n= 2). Ribs 8 (n= 2).

Head slightly depressed and tapering anteriorly. Maximum head width at transverse through opercular hinge; width at hinge approximately equal to maximum head depth but less than maximum body depth. Head profile very gently convex both dorsally and ventrally in lateral view. Head and snout broadly rounded in dorsal view. Opercular margin wide and attached to isthmus. Mouth terminal with opening situated slightly ventral to horizontal through middle of snout. Eye large, midlateral and centered at middle of head depth. Eye prominent in ventral view of head, but somewhat less obvious from dorsal view. Anterior naris located slightly posterior to margin of snout and surrounded by short, anteriorly directed tube. Posterior naris remote from anterior naris; situated anterodorsal to orbit and along vertical through anterior margin of orbit. Posterior naris with very short, fleshy flap anteriorly. No barbel associated with naris. Maxillary barbel long, slender, and extending to vertical through anterior one-third of dorsal-fin base. Lateral mental barbel somewhat longer than medial mental barbel and extending posteriorly slightly beyond vertical through posterior margin of eye.

Dorsal-fin rays II,5. Dorsal-fin height slightly greater than body depth at dorsal-fin origin. Tip of adpressed dorsal fin extends beyond vertical through pelvic-fin origin. First branched dorsal-fin ray slightly longer than dorsal-fin spine; remaining fin-rays progressively decreasing in length posteriorly with overall fin margin concave. Last fin-ray without posterior membranous attachment to body. Dorsal-fin spine stout; bearing slender, widely spaced serrations along distal half of anterior margin. Most of serrations aligned at right angles relative to axis of dorsal spine, but more distally directed near tip of spine. Serrations less obvious in smaller individuals. Serrations along distal portion of posterior margin of spine similar in size and spacing to those along anterior margin, but limited to 2 or 3 serrations along distal portion of spine. Adipose fin small; rounded dorsally in lateral profile. Adipose-fin origin situated slightly anterior of vertical through posterior limit of anal-fin base.

Anal-fin rays iii,7. Anal-fin origin situated posterior of vertical through tip of pelvic fin. Tip of adpressed anal fin falling distinctly short of anterior most procurrent caudal-fin rays. Base short and largely located anterior to vertical through adipose-fin origin. Fin margin slightly convex with anterior and posterior rays slightly longer. Last fin-ray lacking membranous attachment to body.

Principal caudal-fin rays i,7,8,i. Caudal fin moderately forked, symmetrical; lobes somewhat pointed to rounded. Length of middle caudal-fin rays more than one-half length of longest rays. Procurrent rays dorsally and ventrally symmetrical; anterior most rays originate posterior of middle of caudal peduncle and gradually increase in length posteriorly.

Pectoral-fin rays I,5. Pectoral fin long, slender. Tip of adpressed fin extends slightly beyond vertical through posterior terminus of dorsal-fin base but falls well short of pelvic-fin origin. Pectoral-fin spine long with serrations along distal one-half of anterior margin. Serrations along anterior margin of spine aligned at right angles to axis of spine for slightly over basal one-half of serrated region; serrae becoming increasingly stout and antrorse along distal portion of serrate region. Retrorse serrations present along posterior two-thirds of spine margin; both size of, and spacing between, spines increasing distally. Spines on basal portion of anterior margin of spine more slender than corresponding spines along posterior margin. Branched pectoral-fin rays, particularly medial most ray, becoming progressively shorter posteriorly.

Pelvic-fin rays i,5. Pelvic fin with rounded distal margin; second and third branched rays longest. Pelvic-fin origin located slightly anterior to vertical through tip of adpressed dorsal fin. Fin margin falling slightly short of anal-fin origin.

Color in alcohol. Dark pigmentation on dorsal and dorsolateral portions and to varying degrees lateral and sometimes ventrolateral portions of posterior region of body delimited along distinct margin from unpigmented, very lightly colored remaining regions of body ( Fig. 1 ). Dark pigmentation largely situated dorsal of horizontal through middle of orbit; extending slightly further ventrally overall in smaller examined specimens and reaching to ventral midline of posterior portion of caudal peduncle versus only two-thirds of distance to that point in largest specimen (holotype). Vertically elongate, tear-drop shaped unpigmented area present posteroventral to base of dorsal-fin spine in smaller specimens; that region uniformly dark in larger holotype. Dark pigmentation on caudal peduncle continuous across posterior portion of lateral line and terminating at base of caudal-fin rays or barely extending onto base of few central rays of upper lobe.

Dark pigmentation on dorsal surface of head in largest specimen (holotype) with rounded area of dark pigmentation joined by less intense coloration posteriorly to dark pigmentation of dorsal portion of body. Rounded area of dark pigmentation on dorsal surface of head continuous anteriorly with anterolaterally directed, broad band of dark pigmentation extending forward on each side to barely surround each posterior nostril. Contralateral anterolaterally directed bands jointly form V-shaped pattern with base pointed posteriorly. Dark pigmentation on dorsal surface of head in smaller specimens more extensive than in holotype andseamlesslycontinuousposteriorlywithdarkpigmentation of dorsal portion of body. Smaller individuals with dark pigmentation of dorsal region of head continuing anteriorly to beyond posterior nostril, but with slightly longitudinally elongate, ovoid, unpigmented area middorsally in region between anterior portions of orbits. Scattered concentrations of groups of dark chromatophores forming irregularly shaped spots posterior to orbit and on opercle in specimens of all sizes; spots more obvious in largest individual (holotype). Ventral surface of head unpigmented. Basal portion of maxillary barbel with dorsal series of dark chromatophores. Remainder of maxillary barbel as well as both mental barbels lacking dark pigmentation.

Dorsal fin with concentration of dark chromatophores covering base of spines and two anterior branched rays; remainder of fin unpigmented. Adipose fin unpigmented. Pectoral-fin spine with few scattered dark chromatophores on medial most portion of dorsal surface. Remainder of spine and all fin-rays otherwise unpigmented. Pelvic and fins hyaline. Dark pigmentation of caudal peduncle extends very short distance onto basal portion of dorsal lobe of caudal fin in some individuals. Remainder of fin hyaline.

Color in life. Overall coloration pattern of strongly contrasting dark and light coloration as in preserved specimens, but with dark pigmentation more intense. Regions of head and body lacking dark pigmentation somewhat translucent. Slight bluish tint on lateral surfaces of body. Dorsal and lateral surfaces of head with distinctive lightly colored to translucent areas on dorsal portion of the snout, posterior nuchal plate region, and posterodorsal to orbit. Region posterior to orbit with evident oval black surface blotch. All fins hyaline. (Description based on photographs by Heriberto Gimenes Junior of specimens captured October 2013 in the rio Jamanxim, Fig. 2 ).

Distribution. Examined specimens of Tatia melanoleuca all originated from the rio Teles Pires in the rio Tapajós catchment in the southern portion of the Amazon basin ( Fig. 3 ). Photographed (but not vouchered) evidently conspecific specimens originated in the rio Jamanxim (see Color in Life above), a right bank tributary of the rio Tapajós immediately north of the rio Teles Pires.

Ecological notes. A population of Tatia melanoleuca collected in the rio Jamanxim by H. G. Junior inhabited a 2 m deep stretch of the river characterized by clear water and somewhat lentic to slow flowing waters. The substrate in the sampled area consisted primarily of sand and rocks with some submerged tree trunks. Tatia melanoleuca was collected near the river margin at twilight while searching for food on the water surface. This activity period and feeding behavior is typical across the Centromochlinae.

Etymology. The species epithet, melanoleuca , is from the Greek melano, meaning black, and leukos, meaning white, in allusion to its black-and-white color pattern. An adjective.

Figures

Fig. 1. Tatia melanoleuca, new species, MZUSP 114670, holotype, female, 32.4 mm SL, Brazil, along border between Pará and Mato Grosso states, Jacareacanga, rio Teles Pires, close to Sete Quedas, upper rio Tapajós basin; dorsal, lateral and ventral views. Scale bar = 0.5 cm.

Fig. 2. Life coloration of specimen of Tatia melanoleuca collected in rio Jamanxim, tributary to upper rio Tapajós basin. Photograph courtesy of Heriberto Gimenes Junior.

Fig. 3. Map of southeastern Amazon basin showing location of type locality of Tatia melanoleuca.