Parotocinclus yaka, Lehmann & Lima & Reis, 2018

Lehmann, Pablo, Lima, Flávio C. T. & Reis, Roberto E., 2018, Parotocinclus yaka, a new species of armored catfish (Loricariidae: Hypoptopomatinae), from the Amazon basin in Brazil, Zootaxa 4521 (4), pp. 584-592 : 586-591

Parotocinclus yaka , new species

urn:lsid:zoobank.org:act:DEED227E-C8EE-426E-9FC3-E706166E5622

( Fig. 1 )

Parotocinclus polyochrus (not Schaefer): Lima et al., 2005: 219 -220 (upper Rio Tiquié; short description, ecological comments).

Holotype. MZUSP 123655 , 30.1 mm SL, female, Brazil, Amazonas , Rio Tiquié drainage, Igarapé Açaí near São Pedro Village, approx. 00°16’N 69°58’W, 2 Nov 2002, F. C. T. Lima et al.

Paratypes. MZUSP 81408 , 20 , 12.1 - 29.9 mm SL (6, 17.7-29.9 mm SL) , ANSP 206002 , 2 (17.6-18.5 mm SL) , ZUEC 17032 , 2 (17.5-19.2 mm SL), and MCP 53639, 5 , 20.4 - 25.8 mm SL (4, 25.1–25.8 mm SL) + 2 c&s, 24.4– 29.6 mm SL, collected with the holotype . MZUSP 85053 , 2 , 23.9 – 24.8 mm SL, Brazil, Amazonas , black water creek tributary to Rio Tiquié near Fronteira Village, approx. 00°15’N 70°02’W, 24 Jun 2004, F. C.T. Lima col. MZUSP 93308 , 2 , 17.1 – 20.8 mm SL, Brazil, Amazonas , Igarapé Cunuri (or Macucu ), on opposite shore of São José II Village, approx. 00°13’N 69°36’W, 16 Nov 2006, F. C.T. Lima col.

Diagnosis. Parotocinclus yaka is distinguished from its congeners from northeastern and southeastern Brazilian rivers ( P. arandai , P. bahiensis , P. bidentatus , P. cabessadecuia , P. cearensis , P. cesarpintoi , P. cristatus , P. doceanus , P. fluminense , P. haroldoi , P. jequi , P. jimi , P. jumbo , P. maculicauda , P. minutus , P. muriaensis , P. planicauda , P. prata , P. robustus , P. seridoensis , P. spilosoma , and P. spilurus ) in having the cheek canal plate elongated posteriorly on the ventral surface of the head and contacting the cleithrum (vs. canal plate rounded, not elongated posteriorly and not contacting the pectoral girdle). Parotocinclus yaka is distinguished from all other congeners from the Amazon, Orinoco and the Guianas by having conspicuous dark dots smaller than a pupil diameter, distributed dorsally and laterally on the head ( Fig. 2 ; vs. absence of such pigmentation pattern or dark dots broadly distributed dorsally and ventrally on body ( Fig. 3c ) in Parotocinclus variola ). The new species further differs from P. polyochrus , P. longirostris , and P. eppleyi by lacking a Y-shaped light marking dorsally on the head ( Fig. 3d ), from posterodorsal orbital margin to posterior parieto-supraoccipital tip (vs. Y-shaped light markings ( Fig. 3a,b ) present on dorsum of head). The new species is distinguished from P. variola , P. collinsae , and P. halbothi , by lacking unicuspid accessory teeth on both the premaxilla and dentary (vs. accessory teeth present) and, from the last two species, by having a triangular patch of dark pigmentation on the anterior portion of the dorsal-fin membrane (vs. the absence of such pigmentation). Parotocinclus yaka differs from P. dani by having an adipose fin (vs. adipose fin absent); and from other congeners in having more oral teeth: 38–43 premaxillary and 37–42 dentary teeth (vs. 19–29 and 17–23 in P. amazonensis and P. aripuanensis , 15–28 and 16–27 in P. eppleyi , 25–28 and 25–26 in P. britskii , and 15–25 and 15–22 in P. dani ).

Description. Proportional measurements in Table 1. Dorsal profile of head concave from snout tip to naris, convex from naris to parieto-supraoccipital tip and straight to slightly concave from that point to origin of dorsal fin. Dorsal profile of body straight and posteroventrally slanted from dorsal-fin origin to insertion of caudal fin. Trunk roundly triangular and caudal peduncle rounded to ovoid in cross section, slightly flattened ventrally and compressed caudally. Body progressively narrowing posteriorly from cleithrum.

Head slightly convex between orbits; dorsal margin of orbit slightly elevated. Snout elongated, depressed, its anterior margin rounded dorsal view, with small depression in front of naris. Eye positioned dorsolaterally, comparatively small, with iris operculum vestigial. Posterior tip of parieto-supraoccipital with small patch of odontodes only slightly enlarged relative to those of remainder of head and predorsal area. Odontodes on head and trunk otherwise of uniform size and distribution. Enlarged odontodes present on most of border of snout, especially on rostral and postrostral plates; enlarged odontodes curved and posteriorly oriented. Cheek canal plate bent and elongated posteroventrally, contacting cleithum. Lips rounded, narrow, covered with minute papillae; papillae decreasing in size towards lip margin. Lip margin with uniformly distributed papillae forming delicate fringe. Maxillary barbel short; mostly adnate to lower lip. Teeth slender, bifid. Larger, medial cusp blade-like and slightly rounded, not elongated. Smaller, lateral cusp minute and pointed. Premaxillary teeth 38–43 (39); dentary teeth 37– 42 (41); accessory teeth absent.

Body entirely covered by dermal plates except for ventral surface of head around lips, area immediately surrounding pectoral- and pelvic-fin insertions, and area around anus. Dermal plates of dorsum and abdomen uniformly covered with small odontodes arranged in longitudinal rows. Lateral plates arranged in five longitudinal series on trunk. Dorsal plate series complete, with 20 plates; mid-dorsal series incomplete, with 5–7 plates; middle series complete, with two ossified tubes and 22–23 plates. Lateral line either uninterrupted or with six anterior plates bearing canal followed by one unperforated plate, then 14–15 posterior plates bearing canal, and 1–2 terminal plates without canal. Mid-ventral series incomplete with 14–16 plates; series terminating below adipose fin. Ventral series complete and continuous from pelvic-fin origin to caudal-fin base, with 19–20 plates. Predorsal plates forming two transverse rows anterior to nuchal plate. Single preadipose azygous plate. Coracoid completely exposed ventrally. Cleithrum mostly exposed but covered by skin medially; arrector fossa opened medially but covered by a small plate in large specimens. Lateral abdominal plates 3–5 (4/5); plates transversely elongate, clearly arranged in line between coracoid and pelvic-fin origin. Middle abdominal plates 7–8 (8), transversely elongate, arranged in one longitudinal series covering most of abdominal surface between pectoral girdle and preanal shield. Posterior middle abdominal plates between pelvic fins sometimes smaller and arranged in 2–3 rows transversely. Preanal shield well developed, formed by two large, paired quadrangular plates. Total vertebrae 27– 28.

Dorsal-fin rays I,7; spine slightly arched. Dorsal-fin origin at or slightly posterior to vertical through pelvic-fin origin. Dorsal-fin spinelet present, plate-like and roundly triangular, with paired lateral tips and slightly v -shaped ( Fig. 4 ). Spinelet articulated to first dorsal-fin pterygiophore and dorsal-fin spine locking mechanism functional. Adipose fin small. Pectoral-fin rays I,6. Large spine slightly arched; tip of adpressed spine reaching between middle and distal third of pelvic fin. Pectoral-fin axillary slit present, with large slanted opening ventral to tip of posterior process of cleithrum. Pelvic-fin rays i,5. Fin short, with tip of adpressed fin almost reaching to anal-fin origin in males, shorter in females. Adult males with fleshy flap along posterodorsal margin of thickened first pelvic-fin ray. Anal-fin rays i,5. Caudal-fin rays i,14,i, with lower and upper unbranched ray of same length.

Color in alcohol. Dorsal and lateral portions of head and trunk light to dark brown and ventral surface cream to pale yellow. Dorsal surface of snout with inconspicuous Y-shaped light mark in front of eyes, wider at snout tip. Posterior portion of parieto-supraoccipital and predorsal region conspicuously lighter than surrounding areas, but not forming a Y-shaped mark. Dorsal and especially lateral surface of head with small dots, smaller than pupil diameter, formed by concentration of black chromatophores. Pigmentation also concentrated around pores of sensory lateral system. Trunk with three conspicuous light cream-colored bars, extending transversely from dorsal midline to ventral surface, but sometimes interrupted at lateral midline causing a slight zig-zag pattern. First bar situated immediately posterior to dorsal-fin base; interrupted by dark pigmentation at lateral midline, and continuing nearly to anal-fin base. Second light bar on caudal peduncle immediately posterior to adipose fin and usually uninterrupted. Third bar immediately anterior to caudal fin and interrupted at lateral midline. Ventral surface mostly unpigmented, but small dark spots sometimes on cheek canal plate, and caudal peduncle crossed by 3–4 dark bars continuing ventrally from lateral dark color. Fins with transverse, inconspicuous brown bands formed by concentration of chromatophores on rays; bands more visible on leading rays. Dorsal-fin spine with large dark brown triangular spot on anterior half of rays and fin membrane, and less conspicuous irregular dark band and on posterior half of rays. Pectoral-fin spine with 3–4 dark spots, branched rays with 2–3 irregular dark bands. Pelvic fin with two irregular bands. Anal fin with dark base anteriorly and one additional dark band on posterior half of rays. Adipose-fin with one dark spot at anterior portion of membrane. Caudal fin with wide dark band at base, contiguous with dark color on caudal peduncle and posteriorly slanted, and one conspicuous dark brown transverse band on posterior half, but leaving tips of outermost rays hyaline.

Sexual dimorphism. Males possess a small, conic urogenital papilla behind the anal opening and a distinct fleshy flap along the posterodorsal margin of thickened first pelvic-fin ray, both features are absent in females. The pelvic-fin rays of males almost reach to the anal-fin origin, but fall well short of that point in females, and pectoralfin spine is longer than that of females (27.2–32.1, mean 28.9 in males vs. 22.8–29.1, mean 25.8 in females).

Distribution and habitat. Parotocinclus yaka is currently known from three localities in northwestern portion of the Amazonas State of Brazil, close to the border with the Vaupés Department of Colombia ( Fig. 5 ). All three sites of collection are relatively large forest creeks, with clear to slightly dark water, tributaries to the Rio Tiquié, wide enough to have direct penetration of sunlight. All specimens of Parotocinclus yaka were collected while attached to branches of fallen trees in areas with moderate current.

Etymology. Parotocinclus yaka in named after yaka , the common name for non-loricariine loricariids in both languages of the Tukano and the Tuyuka ethnic groups of the upper Rio Tiquié ( Lima et al., 2005).

Conservation assessment. The extinction risk of Parotocinclus yaka is assessed as low despite the limited knowledge of its geographic distribution. The species is so far known from three localities in the upper Rio Tiquié basin, in the upper Rio Negro, with an Extension of Occurrence (EOO) calculated by the convex polygon of those three localities of 60 square kilometers. Nonetheless, additional collecting effort in the region will likely reveal a broader distribution in the Rio Tiquié and perhaps in the Rio Uaupés basin, both in Brazil and Colombia. As threats to the species were not detected and the area is largely well preserved, P. yaka is tentatively categorized as Least Concern (LC) according to the International Union for Conservation of Nature (IUCN) categories and criteria ( IUCN Standards and Petitions Subcommittee, 2017). Additional collecting efforts should be conducted in that region in order to better understand the geographic distribution of this species.

Figures

FIGURE 1. Holotype of Parotocinclus yaka, female, 30.1 mm SL, MZUSP 123655. Brazil, Amazonas, Rio Tiquié basin, Igarapé Açaí near São Pedro Village.

FIGURE 2. Parotocinclus yaka, MZUSP 85786, head, lateral view, left side. Scale bar = 2 mm.

FIGURE 3. Color pattern of Parotocinclus showing markings of dorsum of head. A. Parotocinclus longirostris, MZUSP 85768; B. Parotocinclus polyochrus AMNH 74482, holotype); C. P. variola, MCP 48244; and D. P. yaka, MZUSP 81408. Scale bar = 5 mm.

FIGURE 4. Parotocinclus yaka, MZUSP 85786, dorsal-fin spinelet, dorsal view, anterior towards top. Scale bar = 500 µ.

FIGURE 5. Drainage map of the upper Amazon basin showing the localities of Parotocinclus yaka. Red dot symbol is typelocality and may represent more than one lot or locality.