Hisonotus oliveirai, Roxo, Fabio F., Zawadzki, Claudio H. & Troy, Waldo P., 2014

Roxo, Fabio F., Zawadzki, Claudio H. & Troy, Waldo P., 2014, Description of two new species of Hisonotus Eigenmann & Eigenmann, 1889 (Ostariophysi, Loricariidae) from the rio Parana-Paraguay basin, Brazil, ZooKeys 395, pp. 57-78 : 58-65

Hisonotus oliveirai sp. n. Figure 1; Table 1

Holotype.

MZUSP 115061, 26.4 mm SL, female, Brazil, Paraná State, boundary between municipalities of Cambira and Apucarana, ribeirão Cambira, affluent of rio Ivaí, upper rio Paraná basin, 23°38'54"S, 51°29'58"W, coll. Zawadzki CH, de Paiva S, 29 October 2007.

Paratypes.

All from Brazil, Paraná State. DZSJRP 18244, 3 males, 26.3−26.8 mm SL, ribeirão Salto Grande, rio Ivaí basin, municipality of Maria Helena, 23°37'08"S, 53°12'18"W, coll. Graça WJ, 30 December 2004. LBP 7358, 1 female, 28.4 mm SL, 1 unsexed, 12.4 mm SL, ribeirão Keller, rio Ivaí basin, boundary between municipalities of Marialva and Bom Sucesso, 23°38'30"S, 51°51'33"W, coll. Devidé R, 15 October, 2002. LBP 13332, 1 male, 23.2 mm SL, 1 unsexed c&s, 23.7 mm SL, rio Mourão, rio Ivaí basin, municipality of Campo Mourão, 24°02'23"S, 52°16'22"W, coll. Zawadzki CH, November 2010. LBP 13333, 1 male, 23.6 mm SL, 1 female, 25.4 mm SL, rio Mourão, rio Ivaí basin, municipality of Campo Mourão, 24°02'23"S, 52°16'22"W, coll. Pavanelli CS, 4 December 2006. LBP 13334, 1 male, 24.9 mm SL, ribeirão Keller, rio Ivaí basin, boundary between municipalities of Marialva and Bom Sucesso, 23°38'30"S, 51°51'32"W, coll. Zawadzki CH, November 2010. LBP 13335, 1 male, 26.0 mm SL, ribeirão Salto Grande, rio Ivaí basin, municipality of Maria Helena, 23°37'08"S, 53°12'18"W, coll. Graça WJ, 30 December 2004. LBP 14917, 4 females, 28.8−29.6 mm SL, 2 males, 26.6−27.4 mm SL, ribeirão Cambira, rio Ivaí basin, boundary between municipalities of Cambira and Apucarana, 23°58'54"S, 51°29'58"W, coll. Zawadzki CH, de Paiva S, 29 November 2007. LBP 17578, 3 females, 27.7−30.4 mm SL, 2 males, 25.4−26.1 mm SL, rio Mourão, rio Ivaí basin, boundary between municipalities of Engenheiro Beltrão and Quinta do Sol, 23°49'41"S, 52°11'43"W, coll. Zawadzki CH, Ruiz HB, Vieira RS, 01 April 2013. MCP 47860, 1 male, 25.6 mm SL, 1 female, 25.9 mm SL, ribeirão Salto Grande, rio Ivaí basin, municipality of Maria Helena, 23°37'08"S, 53°12'18"W, coll. Graça WJ, 30 December 2004. NUP 3578, 7 females, 27.8−28.1 mm SL, 8 males, 24.7−26.8 mm SL, 1 female c&s, 27.6 mm SL, 1 male c&s, 25.5 mm SL, ribeirão Salto Grande, rio Ivaí basin, municipality of Maria Helena, 23°37'08"S, 53°12'18"W, coll. Graça WJ, 30 December 2004. NUP 7065, 1 male, 23.3 mm SL, 1 female, 25.4 mm SL, 1 c&s unsexed, 24.5 mm SL, rio Mourão, rio Ivaí basin, municipality of Campo Mourão, 24°02'23"S, 52°16'22"W, coll. Zawadzki CH, 7 April 2009. NUP 9839, 1 male, 25.3 mm SL, 1 female, 25.8 mm SL, 1 female c&s, 25.0 mm SL, collected with holotype. NUP 15614, 10, 3 males, 25.9−26.5 mm SL, 7 females, 27.2−29.9 mm SL, rio Mourão, rio Ivaí basin, municipality of Engenheiro Beltrão, 23°37'41"S, 52°03'38"W, coll. Zawadzki CH, Ruiz HB, Silva HP, 22 October 2012. ZUEC 8006, 2, unsexed, 25.0−27.9 mm SL, rio Mourão, rio Ivaí basin, municipality of Engenheiro Beltrão, 23°37'41"S, 52°03'38"W, coll. Zawadzki CH, Ruiz HB, Silva HP, 22 October 2012. ZMA 250.056, 2, 1 male, 26.1 mm SL, 1 female, 25.6 mm SL, rio Mourão, rio Ivaí basin, municipality of Engenheiro Beltrão, 23°37'41"S, 52°03'38"W, coll. Zawadzki CH, Ruiz HB, Silva HP, 22 October 2012.

Diagnosis.

Hisonotus oliveirai can be distinguished from all congeners, except Hisonotus insperatus Britski & Garavello, 2003, Hisonotus luteofrenatus and Hisonotus paresi , by having odontodes forming longitudinally aligned rows (one odontode after the other, but not necessarily forming parallel series) on head and trunk, Fig. 2(A), (B) (vs. odontodes not forming longitudinally aligned rows). Additionally, the new species can be distinguished from all congeners except Hisonotus insperatus , Hisonotus luteofrenatus , Hisonotus paresi , and Hisonotus piracanjuba by having a pair of rostral plates at the tip of the snout (vs. a single rostral plate). Moreover, Hisonotus oliveirai can be further distinguished from all congeners except Hisonotus bockmanni , Hisonotus chromodontus , Hisonotus insperatus , Hisonotus luteofrenatus , and Hisonotus paresi by having a functional v-shaped spinelet (vs. spinelet non-functional, square-shaped, or absent). The new species can be distinguished from Hisonotus bockmanni and Hisonotus paresi by lacking contrasting dark geometric spots on the anterodorsal region of the body (vs. presence); from Hisonotus insperatus by having small, inconspicuous odontodes forming rows on the head and trunk (Fig. 2A, B; vs. large, conspicuous odontodes forming rows on the head and the trunk, Fig. 2E, F), a deeper head 51.6−59.2% HL (vs. 44.3−48.7% HL) and higher suborbital depth 20.9−25.5% HL (vs. 16.6−20.1% HL); from Hisonotus luteofrenatus by having a deeper caudal peduncle 10.8−12.5% SL (vs. 8.9−10.2% SL) and shorter snout 46.9−52.2% HL (vs. 67.0−75.3% HL); from Hisonotus paresi by a having deeper head 51.6−59.2% HL (vs. 42.4−47.7% HL), more premaxillary teeth 11−18 (vs. 6−10), and more dentary teeth 11−15 (vs. 4−7); from Hisonotus piracanjuba by having a deeper caudal peduncle 10.8−12.5% SL (vs. 8.3−9.5% SL), and shorter snout 46.9−52.2% HL (vs. 67.7−72.7% HL).

Description.

Morphometric data presented in Table 1. Maximum body length 28.4 mm SL. Dorsal profile of head slightly convex to straight from upper part of rostrum to posterior margin of nares, convex from eyes to posterior margin of parieto-supraoccipital, and straight to dorsal-fin origin. Dorsal profile of trunk slightly concave and descending from dorsal-fin origin to end of dorsal-fin base, straight to caudal peduncle. Ventral profile strongly concave from snout tip to opercular region; convex from opercular region to anal-fin origin; concave to caudal-fin insertion. Greatest body depth at dorsal-fin origin (18.6−23.9% SL). Greatest body width at opercular region, gradually decreasing towards snout and caudal fin. Cross-section of caudal peduncle almost ellipsoid; rounded laterally and almost flat dorsally and ventrally.

Head rounded in dorsal view, snout round to slightly pointed. Dorsal and ventral series of odontodes along anterior margin of snout completely covering its tip; odontodes larger than remaining ones on head. Odontodes on head and trunk hypertrophied and arranged in longitudinal rows (most prominent on head). Eyes moderately small (13.9−17.6% in HL), dorsolaterally positioned. Lips roundish with papillae uniformly distributed on base of dentary and premaxilla and slightly decreasing distally. Lower lip larger than upper lip; its border fringed. Maxillary barbel present; joined to lower lip by membrane for half its length. Teeth slender and bicuspid; mesial cusp larger than lateral cusp. Premaxillary teeth 11−18. Dentary teeth 11−15.

Dorsal-fin ii,7; dorsal-fin spinelet short and V-shaped; dorsal-fin lock functional; dorsal-fin origin slightly posterior to pelvic-fin origin. Tip of adpressed dorsal fin almost reaching end of anal-fin base. Pectoral-fin i,6; its tip almost reaching middle of pelvic-fin unbranched ray length when depressed. Pectoral axillary slit present between pectoral-fin insertion and lateral process of cleithrum. Pectoral spine supporting odontodes on ventral, anterior and dorsal surfaces. Pelvic-fin i,5; tip of pelvic-fin longest ray almost reaching anal-fin origin when depressed in females and reaching anal-fin origin in males. Pelvic-fin unbranched ray with dermal flap along its dorsal surface in males. Anal-fin i,5; its tip reaching 7th or 8th plate from its origin. Caudal-fin i,14,i; distal margin forked. Adipose-fin absent. Total vertebrae 27.

Body covered with bony plates except above lower lip, around pectoral and pelvic-fin origins and on dorsal-fin base. Cleithrum and coracoid totally exposed. Arrector fossae partially to completely enclosed by ventral lamina of coracoids. Abdomen entirely covered by plates (Fig. 3A); abdomen covered by large, elongate lateral plate series, formed by two lateral rows, approximately of same size; median plates formed by two patterns of plate distributions; first, median plate series not reaching anal shield plates with lateral plate series beginning to contact each other at middle of abdomen; second, median plate series reaching anal shield and lateral plate series remaining separate; anal plates series covered by large square or triangular plates. Body entirely covered laterally by plates (Fig. 3B); mid-dorsal plates poorly developed and reaching middle of dorsal-fin base; median plates series continuous in median portion of body; mid-ventral plates reaching vertical through end of dorsal-fin base.

Parts of dorsal head bone plates presented in Fig. 3C. Snout tip formed by one pair of square rostral plates (r). Nasal (n) rectangular, forming anterior medial nostril margin, posterior nasal margin contacting frontals (f), anterior and lateral margins contacting pre-nasals (pn). Pre-nasals (pn) positioned posterior to rostral plates (r); formed by two large square-shaped plates, one small and triangular and one elongated and rectangular between nares. Posterodorsal head plates consist of compound pterotic (cpt), parieto-supraoccipital (soc) and frontal (f; largest bones of head), prefrontal (pf) and sphenotic (sp). Compound pterotic (cpt) covered with few and small, unclustered fenestra. Lateral surface of head illustrated in Fig. 3D. Posterior rostrum plates pr1-pr2 smallest, rectangular shaped; pr4-pr3 largest, first rectangular and second square. Complete infraorbital plate series (io1-io5), present just above posterior rostrum series, all covered by laterosensory canal system; io2 largest and io5 smallest; io3, io4 and io5 forming inferior orbital margin of eyes. Preopercle (pop) elongate and rectangular, covered by laterosensory canal; preopercle present under pr4, io4 and io5, and upper cp1, cp2 and op. Subocular cheek plates (cp1-cp2) and opercle (op) form posterior lateral margin of head.

Coloration in alcohol.

Pale yellowish ground color. Dorsal surface of head dark brown, except for pale yellowish areas on snout tip, lateral margin of head and tip of parieto-supraoccipital. Three dark-brown saddles crossing dorsum, reaching longitudinal dark stripe on side of trunk: first below dorsal-fin origin, second typically at adipose-fin region, and third at end of caudal peduncle. Ventral region of anal-fin origin with small single-chromatophore spots. Caudal fin hyaline with two black bars; first at caudal-fin origin, second at middle of caudal fin (Fig. 1).

Sexual dimorphism.

Adult males are distinguished by having a papilla at the urogenital opening (vs. papilla absent in females); a pelvic fin that extends beyond anal-fin origin (vs. pelvic fin not reaching anal-fin origin in females); and an unbranched pectoral- and pelvic-fin ray supporting a dermal flap on their proximal dorsal surface in males. Both sexes have a membrane at anal opening; however, the membrane is longer and large in females (Fig. 4A) than in males (Fig. 4D), covering almost the entire urogenital opening.

Distribution.

Hisonotus oliveirai is only known from four small to medium-sized streams, the ribeirão Salto Grande, ribeirão Keller, rio Mourão, and the ribeirão Cambira, all tributaries of the rio Ivaí in the upper rio Paraná basin (Fig. 5A).

Etymology.

The specific epithet oliveirai (a noun in the genitive case) is a patronym honoring professor Claudio Oliveira from the Universidade Estadual Paulista Júlio de Mesquita Filho (UNESP), Botucatu, São Paulo State, in recognition of his dedication and contributions to the studies of Neotropical freshwater fishes.