Hisonotus paresi, 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 : 65-69

Hisonotus paresi sp. n. Figure 6; Table 1

Holotype.

MZUSP 115062, 26.2 mm SL, female, Brazil, Mato Grosso State, municipality of Santo Afonso, riacho Águas Claras, affluent rio Sepotuba, rio Paraguay basin, 14°21'03"S, 57°33'07"W, coll. Troy WP, 14 September 2010.

Paratypes.

All from Brazil, Mato Grosso State, rio Sepotuba basin. DZSJRP 18245, 2 females, 19.9−24.3 mm SL, collected with holotype. LBP 13347, 2 females, 18.9−19.6 mm SL, collected with holotype. LBP 13351, 9, 14.7−24.3 mm SL, riacho Águas Claras, Santo Afonso, 14°21'03"S, 57°33'07"W, coll. Troy WP, April 2012. LBP 13352, 1, 23.7 mm SL, riacho Águas Claras, Santo Afonso, 14°21'03"S, 57°33'07"W, coll. Troy WP, April 2012. LBP 17532, 1 male 22.6 mm SL, 2 female 19.5−23.8 mm SL, 1 unsexed not measured, riacho Maracanã, boundary between municipalities of Santo Afonso and Nova Marilândia, 14°22'40"S, 57°35'11"W, coll. Troy WP, Paliga T, Silva VM, 3 April 2010. NUP 10928, 2 males, 23.2−24.2 mm SL, 2 c&s, 23.6−24.2 mm SL, 1 unsexed not measured, collected with holotype. NUP 10976, 3 unsexed, 16.7−20.5 mm SL, riacho São Jorge, municipality of Santo Afonso, 14°27'26"S, 57°34'34"W, coll. Zawadzki CH, Troy WP, 19 August 2010.

Diagnosis.

Hisonotus paresi can be distinguished from all congeners, except Hisonotus bockmanni , by the presence of contrasting dark geometric spots on the anterodorsal region of body (vs. absence of geometric spots). Additionally, the new species can be distinguished from all congeners, except Hisonotus insperatus , Hisonotus luteofrenatus , Hisonotus oliveirai , Hisonotus piracanjuba ) by having a pair of rostral plates at the tip of the snout (vs. a single rostral plate). Also Hisonotus paresi can be distinguished from all congeners, except Hisonotus insperatus , Hisonotus luteofrenatus and Hisonotus oliveirai by having odontodes forming longitudinally aligned rows on head and trunk, Fig. 2C, D (vs. odontodes not forming longitudinally aligned rows). The new species can be distinguished from Hisonotus bockmanni by having a continuous median series of perforated plate (vs. median plate series of perforated plates discontinuous, that is, with a gap of unperforated plates), by lacking unpaired plates between the contra-lateral dorsal series (vs. having two tiny unpaired plates between the contra-lateral dorsal series, placed eight plates posterior to dorsal fin - see fig. 4 in Carvalho and Datovo 2012), and by having the anterior half of the caudal fin darkly pigmented medially (vs. caudal fin with anterior half hyaline); from Hisonotus insperatus by a longer pectoral-fin spine, 27.0−30.1% in SL (vs. 20.6−25.9%); from Hisonotus luteofrenatus by a longer head 36.1−41.7% SL (vs. 28.8−33.3%), smaller orbital diameter 11.0−14.1% HL (vs. 15.0−18.1%) and shorter snout 50.7−57.1% HL (vs. 67.0−75.3%); from Hisonotus oliveirai by lower head depth 42.4−47.7% HL (vs. 51.6−59.2%), fewer premaxillary teeth 6−10 (vs. 11−18) and fewer dentary teeth 4−7 (vs. 11−15); from Hisonotus piracanjuba by longer head 36.1−41.7% SL (vs. 27.9−32.2), deeper caudal peduncle 10.2−11.3% SL (vs. 8.3−9.5%), fewer premaxillary teeth 6−10 (vs. 14−22) and fewer dentary teeth 4−7 (vs. 12−19).

Description.

Morphometric data presented in Table 1. Maximum body length 26.2 mm SL. Lateral profile of head convex; straight from upper part of rostrum to posterior margin of nares, slightly curved from eyes to posterior margin of parieto supraoccipital, almost straight to dorsal-fin origin. Dorsal profile of trunk slightly concave, descending from base of dorsal-fin origin to end of dorsal-fin base, straight to caudal peduncle. Ventral profile slightly concave from snout tip to pectoral-fin origin, convex to anal-fin origin, slightly concave to caudal peduncle. Greatest body depth at dorsal-fin origin (16.9−20.7% 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 slightly pointed, its tip rounded, elongated (50.7−57.1% HL) and depressed in front of each nostril on dorsal surface. Dorsal and ventral series of odontodes completely covering anterior margin of snout; odontodes of snout similar in size to remaining ones found on head. Snout tip lacking band devoid of odontodes. Odontodes on head and trunk well defined and arranged into longitudinal rows (character more prominent in head). Eyes small (11−14.1% HL), dorsolaterally positioned. Lips roundish and papillose; uniformly distributed on base of dentary and premaxilla and slightly decreasing distally. Lower lip larger than upper lip; its border strongly fringed. Maxillary barbel present. Teeth slender and bicupid; mesial cusp larger than lateral cusp. Premaxillary teeth 6−10. Dentary teeth 4−7.

Dorsal-fin ii,7; dorsal-fin spinelet short and V-shaped; dorsal-fin lock functional; its origin slightly anterior to pelvic-fin origin. Tip of adpressed dorsal-fin rays surpassing end of anal-fin base. Pectoral-fin i,6; tip of longest pectoral-fin ray almost reaching half of pelvic-fin length, when depressed. Pectoral axillary slit present between pectoral-fin insertion and lateral process of cleithrum. Pectoral spine supporting odontodes anteroventrally. Pelvic-fin i,5; its tip 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 and 8th from its origin. Caudal-fin i,14,i; distal margin emarginated. Adipose-fin absent. Total vertebrae 27.

Body covered with bony plates except on ventral part of head, around pectoral and pelvic-fin origin and on dorsal-fin base. Cleithrum and coracoid totally exposed. Arrector fossae partially enclosed by ventral lamina of coracoids. Abdomen entirely covered by plates (Fig. 7A), abdomen formed by lateral plate series with elongate and large plates, formed by two lateral plates series, similar in size; median plates formed by one to three plates series reaching anal shield. Lateral of body entirely covered by plates (Fig. 7B); mid-dorsal plates poor developed, reaching middle of dorsal-fin base; median plates not interrupted in median portion of body; mid-ventral plates reaching end of dorsal-fin base.

Parts of dorsal head bone plates presented in Fig. 7C. Snout tip formed by one pair of rostral square-shaped plates (r). Nasal (n) almost rectangular forming anterior medial nostril margin in contact posteriorly with frontals (f) and anteriorly and laterally with pre-nasals (pn). Pre-nasals (pn) positioned posteriorly of rostral plates (r), formed by two large and one small square-shaped plates, and one elongate rectangular shaped between nares. Top of head composed by compound pterotic (cpt), parieto supraoccipital (soc) and frontal (f), largest bones of head, and prefrontal (pf) and sphenotic (sp). Compound pterotic (cpt) fenestrated randomly distributed. Lateral surface of head presented in Fig. 7D. Posterior rostrum plates pr1-pr2 small, and rectangular shaped; pr4-pr3 largest, first rectangular and second square-shaped. Infraorbital plate series complete (io1-io5), present just above posterior rostrum series, all covered by latero-sensory canal system; io2 largest and io5 smallest; io3, io4 and io5 forming inferior orbital margin of eyes; preopercle (pop) elongated and rectangular, covered by latero-sensory canal; preopercle present under 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.

Ground color of dorsal and ventral region of head and trunk pale yellowish. Conspicuous longitudinal dark stripe enlarging from rostral plates to anterior corner of eyes, straightening and bordering on ventral margin of eyes, enlarging again through compound pterotic and lateral series of plates to caudal-fin. Another conspicuous longitudinal dark stripe starting medially at pre-nasal plate region and enlarging on supraoccipital region. Unpigmented portion of snout appears as hyaline v-shaped mark from rostral plate passing through nares to orbital margins. Longitudinal dark stripe from superior portion of sphenotic through mid-dorsal plates to posterior margin of dorsal-fin base. Dark blotch on compound pterotic overlaps mid-dorsal longitudinal dark stripe. Dark saddle on middle portion of predorsal region reaches mid-dorsal longitudinal dark stripe. Overall, pigmentation pattern forms geometric spots on anterodorsal region of body. Three dark saddles usually cross posterodorsal region of body, reaching longitudinal stripe on side of trunk: first saddle at middle of dorsal fin, second at adipose-fin region, and third at end of caudal peduncle. Saddles inconspicuous in some specimens. Ventral region of body almost completely pale yellowish, except few dark spots on caudal peduncle and dark ring at anal-fin origin. Dorsal, pectoral, and pelvic fins with dark chromatophores forming irregular sets of bands: three on dorsal and pectoral fin, and one on pelvic fin. Anal fin with few scattered chromatophores, sometimes forming bands. Caudal fin hyaline, except for dark spot on origin of rays, and dark band on middle of rays (Fig. 6).

Sexual dimorphism.

Adults males have a papilla in urogenital opening (vs. absent in females); have a longer pelvic fin that extends beyond anal-fin origin (vs. pelvic fin not reaching anal-fin origin in females); and have an unbranched pelvic-fin ray supporting a dermal flap along its dorsal surface. Both sex have a membrane on the anal opening; however, this membrane is more developed in females (Fig. 4B) than in males (Fig. 4E), covering almost the entire urogenital opening.

Distribution.

The species is known from three small tributaries the riacho Águas Claras, riacho Maracaña and riacho São Jorge, all draining to the rio Sepotuba, in the upper rio Paraguay basin (Fig. 5B).

Etymology.

The species name paresi (a noun in apposition), refers to the the Paresí Indians who speak Paresí, a branch of the Aruak language. The Paresí used to live throughout most of Mato Grosso State including the municipality of Santo Afonso. Paresí were also some of the main guides of Marechal Cândido Rondon, the famous Brazilian pioneer in this region of Brazil at the beginning of the 18th century.