Curculionichthys sagarana, Roxo, Fabio F., Silva, Gabriel S. C., Ochoa, Luz E. & Oliveira, Claudio, 2015

Roxo, Fabio F., Silva, Gabriel S. C., Ochoa, Luz E. & Oliveira, Claudio, 2015, Description of a new genus and three new species of Otothyrinae (Siluriformes, Loricariidae), ZooKeys 534, pp. 103-134 : 117-122

Taxon classification Animalia Siluriformes Loricariidae

Curculionichthys sagarana sp. n. Figure 11; Table 1

Holotype.

MZUSP 117381, female 23.7 mm SL, Minas Gerais State, municipality of Santo Hipólito, Rio Pardo Grande, Rio das Velhas drainage, Rio São Francisco basin, 18°13'43"S, 44°13'03"W, 17 September 2007, coll. Leal CG, Junqueira NT, Pompeu PS.

Paratypes.

All from Brazil, Minas Gerais State, Rio das Velhas drainage, Rio São Francisco basin: LBP 19983 (1 male, 21.9 mm SL), municipality of Santo Hipólito, Rio Pardo Grande, 18°13'43"S, 44°13'03"W, 11 September 2007, coll. Leal CG, Junqueira NT, Pompeu PS. NUP 9714 (1 female, 24.4 mm SL, 1 male, 22.5 mm SL), municipality of Augusto de Lima, Rio Curimataí, 17°59'33"S, 44°10'48"W, 23 March 2008, coll. Leal CG, Junqueira NT, Pompeu PS. NUP 9715 (2 females, 17.5−18.4 mm SL, 1 male, 21.7 mm SL, 1 c&s sex not determined, 23.3 mm SL), municipality of Santo Hipólito, Rio Pardo Grande, 18°13'43"S, 44°13'03"W, 25 March 2010, coll. Leal CG, Junqueira NT, Pompeu PS. NUP 9716 (4 juveniles, sex not determined, 10.5−17.1 mm SL), municipality of Santo Hipólito, Rio Pardo Grande, 18°13'43"S, 44°13'03"W, 25 March 2010, coll. Leal CG, Junqueira NT, Pompeu PS. NUP 12595 (1 male, 23.0 mm SL), collected with holotype. NUP 12596 (1 female, 24.1 mm SL), municipality of Santo Hipólito, Rio Pardo Grande, 18°13'43"S, 44°13'03"W, 24 March 2008, coll. Leal CG, Junqueira NT, Pompeu PS. NUP 12597 (1 male, 21.7 mm SL), municipality of Santo Hipólito, Rio Pardo Grande, 18°13'43"S, 44°13'03"W, 24 March 2008, coll. Leal CG, Junqueira NT, Pompeu PS. NUP 12614 (1 female, 21.7 mm SL), municipality of Santo Hipólito, Rio Pardo Grande, 18°13'43"S, 44°13'03"W, 11 September 2007, coll. Leal CG, Junqueira NT, Pompeu PS.

Diagnosis.

Curculionichthys sagarana differs from all congeners by having one unpaired platelet on the dorsal portion of the caudal peduncle, Fig. 6 (vs. dorsal portion of caudal peduncle without unpaired platelets). The new species can be further distinguished from all congeners, except Curculionichthys insperatus and Curculionichthys luteofrenatus by having the caudal fin hyaline, with dark blotch limited to caudal peduncle base, Fig. 5C (vs. caudal fin hyaline, with one dark stripe extending from caudal peduncle base to the middle caudal fin rays, and for dark chromatophores irregularly distributed almost forming one or two bands); from Curculionichthys insperatus , Curculionichthys paresi and Curculionichthys sabaji by having more premaxillary teeth 15−19 (vs. 10−12 in Curculionichthys insperatus ; 6−10 in Curculionichthys paresi and 7−12 in Curculionichthys sabaji ) and more dentary teeth 12−18 (vs. 8−12 in Curculionichthys insperatus , 4−7 in Curculionichthys paresi and 7−12 in Curculionichthys sabaji ); from all congeners, except Curculionichthys piracanjuba and Curculionichthys oliveirai , by having all papillae on the lower lip randomly distributed (vs. lower lip with some papillae arranged in a medial longitudinal series extending posterior to dentaries through middle portion of lower lip); from Curculionichthys oliveirai and Curculionichthys coxipone by having the anterior profile of the head pointed (vs. rounded); from Curculionichthys paresi by lacking contrasting dark-brown geometric spots on the anterodorsal region of the body (vs. presence); from Curculionichthys piracanjuba by having odontodes forming longitudinally aligned rows on the head and trunk (vs. odontodes not forming longitudinally aligned rows on the head and trunk); from Curculionichthys sabaji , Curculionichthys coxipone and Curculionichthys paresi by having the cleithrum completely covered with odontodes, Fig. 4D (vs. the cleithrum with an area free of odontodes, Fig. 4A−C); from Curculionichthys insperatus by having small, inconspicuous odontodes forming rows on the head and trunk (vs. large, conspicuous odontodes forming rows on the head and the trunk); from Curculionichthys oliveirai by having 6−9 lateral abdomen plates (vs. 4−5 lateral abdomen plates); from Curculionichthys piracanjuba by not having hypertrophied odontodes on the snout tip (vs. hypertrophied odontodes on the snout tip). Additionally, Curculionichthys sagarana is distinguished by having a deeper caudal peduncle (8.4−9.6 % of SL, vs. 10.8−12.5% of SL in Curculionichthys oliveirai ; 10.2−11.3% in Curculionichthys paresi ); a greater head length (34.8−40.5% of SL, vs. 28.8−33.3% of SL in Curculionichthys luteofrenatus ; 27.9−32.2% of SL in Curculionichthys piracanjuba ); a shorter snout (46.3−52.4% of HL, vs. 67.0−75.3% of HL in Curculionichthys luteofrenatus ; 67.7−72.7% of HL in Curculionichthys piracanjuba ); a shorter interorbital width (27.4−33.6% of SL, vs. 33.3−45.4% of HL in Curculionichthys luteofrenatus ; 36.7−40.9% of HL in Curculionichthys piracanjuba ; 33.8−37.8% of HL in Curculionichthys coxipone ); a deeper head (41.2−49.1% of HL, vs. 51.6−59.2% of HL in Curculionichthys oliveirai ); a shorter dorsal-spine (19.9−24.4% of SL, vs. 25.2−27.0% of SL in Curculionichthys paresi ); and a shorter pectoral-spine (21.5−25.2% of SL, vs. 27.0−30.1% of SL in Curculionichthys paresi ).

Description.

Morphometric and meristic available in Table 1. Small loricariid; largest examined specimen reaching 24.2 mm SL. In lateral view, dorsal profile of head convex from snout tip to posterior margin of parietosupraoccipital, 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 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. Greatest body width at opercular region, gradually decreasing towards snout and caudal fin. Cross- section of trunk and caudal peduncle almost ellipsoid; rounded laterally and almost flat dorsally and ventrally.

Head elliptical in dorsal view; snout round to slightly pointed, its tip rounded, elongated (46.3−52.4% HL), slightly convex between orbits. Dorsal and ventral series of odontodes along anterior margin of snout completely covering its tip; odontodes at same size than remaining ones on head. Odontodes on head and trunk hypertrophied and arranged in longitudinal rows (most prominent on head). Eyes moderately small (13.8−16.3% HL), dorsolaterally positioned. Lips roundish with papillae arranged in a medial longitudinal series extending posterior to dentaries through middle portion of lower lip. Lower lip larger than upper lip; its border fringed. Maxillary barbel present; joined to lower lip. Teeth slender and bicuspid; medial cusp larger than lateral cusp. Premaxillary teeth 15−19. Dentary teeth 12−18.

Dorsal fin ii, 7; dorsal fin spinelet short and V-shaped (Fig. 12A); dorsal fin lock functional; dorsal fin origin slightly posterior to pelvic fin origin. Tip of adpressed dorsal fin reaching anal fin insertion. Pectoral fin i, 6; its tip reaching beyond pelvic fin insertion when depressed. Presence of pectoral axillary slit between pectoral fin insertion and lateral process of cleithrum variable; absent in some specimens. Pectoral spine supporting odontodes on ventral, anterior and dorsal surfaces. Pelvic fin i, 5; tip of pelvic fin unbranched 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 dorsal surface in males. Anal fin i, 5; distal margin slightly convex. Caudal fin i, 7-7, i; slightly emarginate; both unbranched rays of same size. Adipose fin absent. Total vertebrae 28.

Body covered with bony plates, except above head, around pectoral and pelvic-fin origins and on dorsal fin base. Cleithrum and coracoid entirely exposed. Arrector fossae partially to completely enclosed by ventral lamina of coracoids. Abdomen entirely covered by plates (Fig. 12B); lateral plates series with elongate and large plates formed by two lateral plate series, similar in size; median plates formed by two to three irregular plate series reaching anal shield and lateral plate series; anal plates series covered by large square plates. Body entirely covered laterally by plates (Fig. 12C); mid-dorsal plates poorly developed and reaching end of dorsal fin base; median plates series continuous in median portion of body; mid-ventral plates reaching caudal peduncle origin. Dorsal portion of caudal peduncle with one unpaired platelet.

Parts of dorsal head bone plates presented in Fig. 12D. Snout tip formed by one pair of rostral rectangular-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 triangular-shaped plates, and one elongate oval 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. Posterior rostrum plates pr1-pr2 small and triangular-shaped; pr4-pr3 largest, and rectangular-shaped. Infraorbital plate series complete (io1-io5), present just above posterior ros trum 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 upper cp1, cp2 and op. Supra-opercular plate (spop) present just above preopercle, covered by latero-sensory canal. Subocular cheek plates (cp1-cp2) and operculum (op) form posterior lateral margin of head.

Color in alcohol. Ground color of dorsal and ventral region of head and trunk pale yellowish; dorsal portion darker than ventral. Four dark saddles along dorsal portion of body: first at dorsal fin origin; second at end of dorsal fin; third at middle of caudal peduncle; and fourth at upper caudal peduncle adpressed ray origin. Dorsal, pectoral, and pelvic fins hyaline. Caudal fin hyaline, with dark blotch limited to caudal peduncle base, and with dark chromatophores irregular distributed almost forming one band.

Sexual dimorphism. Adults males have a papilla in urogenital opening (vs. absent in females); a longer pelvic fin that extends beyond anal fin origin (vs. pelvic fin not reaching anal fin origin in females); nares opening wider (vs. nares opening narrower); and an unbranched pelvic fin ray supporting a large dermal flap along its dorsal surface. Both sex have a membrane on anal opening; however, this membrane is more developed in females than in males, covering almost the entire urogenital opening (see reference to this last character in Roxo et al. 2014b).

Distribution.

The new species Curculionichthys sagarana are known from two localities along Rio das Velhas drainage: one at Rio 13 de Maio, one at Pardo Grande, and one at Rio Curimataí, all in Rio São Francisco basin, Minas Gerais State, Brazil (Fig. 8).

Etymology.

The specific name “sagarana” is a hybrid of two words, “saga” of Germanic origin that means heroic song and “rana” from Tupi-Guarani language that means “similarity”. The word sagarana is in reference to the book of a Brazilian author João Guimarães Rosa published in 1946 about the history of people from Minas Gerais State living in the region of Rio das Velhas.

Comparative remarks.

The new species Curculionichthys sagarana is similar in external morphology with Curculionichthys insperatus , primarily the general pattern of coloration of the body. However, Curculionichthys sagarana can be distinguished by the presence of one unpaired platelet on the dorsal portion of caudal peduncle, a character apparently present only in this new species, more premaxillary and dentary teeth, and small, inconspicuous odontodes forming rows on the head and trunk.