Parotocinclus pentakelis, Roxo & Messias & Silva, 2019

Roxo, Fabio F., Messias, Felipe L. & Silva, Gabriel S. C., 2019, A new species of Parotocinclus (Loricariidae: Hypoptopomatinae) from Rio Tocantins basin, Brazil, Zootaxa 4646 (2), pp. 346-356 : 347-350

Parotocinclus pentakelis , new species

Fig. 1 and Table I

Holotype. MZUSP 124900 , 22.8 mm SL, female, Brazil, Tocantins State, municipality Lavandeira, Rio Palmas, Rio Tocantins basin; 12 o 48’ 05” S; 46 o 28’ 38” W; col. R. Devidé, G. S. C. Silva, C. Arraya & B. F. Melo, 2 July 2017.

Paratypes. LBP 25358 (two specimens 13.2–15.3 mm SL), collected with the holotype . LBP 26866 (two specimens 21.8–22.8 mm SL, one c&s specimen 23.1 mm SL), collected with the holotype . NUP 21298 (two specimens 22.1–23.5 mm SL), collected with the holotype . MZUSP 84141 (two specimens 20 2–22 7 mm SL), Brazil, Tocantins State, municipality Lavandeira, Rio Palmas, Rio Tocantins basin; 12 o 48’ 05” S; 46 o 28’ 38” W; col. C. R. Moreira & J. C. Nolasco, 24 November 2002 . MZUSP 84157 (six specimens 19.5–23.1 mm SL), Brazil, Tocantins State, municipality Porto Alegre do Tocantins, Rio Manuel Alves da Natividade, Rio Tocantins basin; 11 o 36’ 41” S; 47 o 02’ 39” W; col. C. R. Moreira & J. C. Nolasco, 14 November 2002 .

Diagnosis. The new species Parotocinclus pentakelis can be distinguished from all congeners (except P. dani Roxo, Silva & Oliveira, 2016 ) by a unique pattern of body coloration with five conspicuous dark bars, Figs. 1 , 2 , 3a (vs. four or three in all remaining species of Parotocinclus ) and by absence of an adipose fin (vs. presence of an adipose fin). Additionally, the new species can be distinguished from P. dani by absence of a small platelet at the typical adipose-fin location (vs. presence of a small platelet at typical adipose-fin region), by absence of conspicuous dark dots broadly distributed on the body (vs. absence of this pigmentation pattern) and by absence of a triangular dark blotch at the anterior base of the dorsal fin (vs. presence of a triangular dark blotch). Additionally, the new species differs from all congeners from the coastal drainages of the Brazilian shield from south and northeastern Brazil by presence of a V -shaped spinelet (vs. rounded or rectangular spinelet).

Description. Small-sized loricariid, holotype 22.8 mm SL, paratypes 13.2–23.5 mm SL. In dorsal view, snout tip rounded, elongated (49.6–55.2 mm HL). Snout margin completely covered by odontodes, larger than remaining ones on head. Odontodes on head and trunk well defined, and arranged in longitudinal rows, not forming parallel series. Eye median-sized and rounded, situated dorsolaterally at midpoint length of head. No ridge between eyes and nares. Supraoccipital process not elevated and without tuft of odontodes in specimens of all sizes. Nasal aperture small. Mouth wide, ventrally-oriented; oral disk rounded with papillae randomly distributed. Lower lip larger than upper, but distant from cleithrum; its border fringed. Maxillary barbel short, slender and free distally. Ventral surface of head naked in area around mouth and between lower lip and cleithrum. Buccal papilla absent. Teeth slender and bicuspid, cusps asymmetrical, main cusp larger than lateral cusp. Premaxillary teeth 15–21. Dentary teeth 14–18.

In lateral view, dorsal profile of head straight from snout tip to interorbital region; slightly convex from this point to posterior margin of parieto-supraoccipital; slightly concave from this point to dorsal fin-insertion; concave and descending from this point to origin of anteriormost caudal fin procurrent ray. Ventral profile of head concave from snout tip to opercular region; straight from this point to anal-fin insertion; concave from this point to first anteriormost caudal-fin procurrent ray.

Greatest body depth at dorsal-fin origin. Greatest body width at cleithral region (24.2–26.2 mm SL), progres- sively narrowing towards snout and caudal fin. Trunk and caudal peduncle almost ellipsoid in cross section. Trunk covered by bony plates, except on area around fin bases and anal-fin insertion. Mid-dorsal series poorly developed reaching vertical line at middle of dorsal fin. Lateral plate series with 21–23 plates; lateral line incomplete, with a gap of two plates along mid-length of body. Mid-ventral series short reaching vertical line at adipose-fin region. Arrector fossae partially enclosed by ventral lamina of coracoid. Abdominal region entirely covered by plates; lat- eral abdominal plate series with three to four plates; 1-3 irregular and large plates on median series; five pre-anal plates.

Dorsal-fin rays II,7; dorsal-fin spinelet V -shaped; second dorsal-fin unbranched ray reaching half of anal-fin unbranched ray when depressed; dorsal-fin locking mechanism functional. Second dorsal-fin unbranched ray covered by odontodes. Pectoral-fin rays I,6; reaching more than two thirds of pelvic-fin unbranched ray when depressed; dorsal surface of pectoral spine covered by odontodes, larger on distal portion. Pectoral-fin axillary slit present and well visible. Pelvic-fin rays i,5; its posterior tip almost reaching anal-fin insertion when depressed in females and extending beyond anal-fin insertion when depressed in males; pelvic-fin spine covered by odontodes, on ventral surface. Anal-fin rays i,5; anal-fin spine covered by odontodes. Caudal-fin rays i,14,i; caudal fin forked, all rays covered with odontodes.

Snout tip formed by a single rostral rectangular-shaped plate in dorsal view. Prenasals plates positioned posteriorly to rostral plate and formed by two large and two small triangular-shaped plates located between nares, and one small, rectangular-shaped plate. Nasal almost rectangular forming anterioromedial nostril margin, contacting frontals. Dorsal surface of head at its posterior portion composed by compound pterotic laterally, parieto-supraoccipital and frontal medially, and sphenotic. Compound pterotic on lateral portion. Postrostral plates rectangular-shaped. Infraorbital series incomplete, with only four bones, present just above postrostral series, all covered by laterosensory canal system. Preopercle elongated and rectangular, covered by laterosensory canal and situated ventral to infraorbital 3 and infraorbital 4, and upper to compound pterotic. Subocular cheek plates and opercle forming posterior lateral margin of head.

Color in alcohol. Dorsal surface of head dark brownish, except for striking V -shaped yellowish tan mark from rostral plate passing through nares to anterior orbital margins. Background color yellowish-brown in dorsal and ventral portions of body. Five dark brownish bars, forming saddles in dorsal view, laterally most broad, sometimes forming a longitudinal stripe on sides of trunk, and crossing to ventral region: first located at dorsal-fin origin, second at end of dorsal-fin base, third at adipose-fin region, and fourth at caudal peduncle and the fifth at caudal fin origin. Dorsal, pectoral, and pelvic fins with dark chromatophores, forming irregular sets of bars: three on dorsal fin, four on pectoral fins, three on pelvic fin, and two to three on anal fin. Dark blotch of pigmentation on posterior portion of caudal peduncle that extends median portion of caudal-fin. Dark chromatophores forming irregular sets of bars at middle and at end of caudal fin.

Color in life. Similar pattern described for alcohol preserved specimens, but with dark-brown background coloration and with pronounced dark chromatophores and bars over body ( Fig. 2 ).

Sexual dimorphism. Males have (1) a papilla urogenital (vs. papilla absent in females); (2) the posterior tip of pelvic fin beyond anal-fin origin (vs. pelvic fin not reaching anal-fin origin in females); and (3) the unbranched pelvic-fin ray supporting a dermal flap on dorsal surface (vs. dermal flap on proximal dorsal surface of pelvic-fin absent in females).

Distribution. Parotocinclus pentakelis is known from two localities of the Rio Tocantins basin ( Fig. 4 ). The type-locality is at Rio Palmas (12 o 48’ 05” S; 46 o 28’ 38” W), municipality of Lavandeira, southeastern of Tocantins state. The new species is also found in a second locality at Rio Manuel Alves da Natividade (11 o 36’ 41” S; 47 o 02’ 39” W), a river draining directly to Rio Tocantins, municipality of Porto Alegre do Tocantins.

Habitat. The new species was found associated with marginal vegetation of median size rivers, ( Fig. 5 ) that is composed of grasses, shrubs and large trees. The waters where this species is found clear fast-flowing 50–100 cm near margins.

Etymology. The specific name “ pentakelis ” comes from the Greek penta (five) and kelis (stain) related to the color pattern of the body with four transverse dark bars.

Figures

FIGURE 1. Parotocinclus pentakelis, MZUSP 124900, holotype, 22.8 mm SL, rio Palmas, rio Tocantins basin.

FIGURE 2. Parotocinclus pentakelis, live specimen, MZUSP 124900, holotype, 22.8 mm SL.

FIGURE 3. Body color pattern variation between a) Parotocinclus pentakelis, paratypes, NUP 21298, 22.8 mm SL. b) P. dani, holotype, MZUSP 120737, holotype, 27.3 mm SL; c) Parotocinclus variola, ICNHHN 18685, 25.9 mm SL; d) Curculionichthys tukana, holotype, MZUSP 123010, 23.4 mm SL; e) Hisonotus alberti, holotype, MZUSP 118845, 33.5 mm SL.Arrows indicate transverse dark bars.

FIGURE 4. Type locality of Parotocinclus pentakelis (black star) at rio Palmas, and paratypes locality at rio Manuel Alves da Natividade (black circle), rio Tocantins basin.

FIGURE 5. Type locality of Parotocinclus pentakelis at rio Palmas, rio Tocantins basin, 12o 48’ 05” S; 46o 28’ 38” W. Species were found associated with marginal vegetation.