Corumbataia lucianoi, Silva & Roxo & Souza & Oliveira, 2018

Silva, Gabriel S. C., Roxo, Fabio F., Souza, Camila S. & Oliveira, Claudio, 2018, Two new species of Corumbataia (Hypoptopomatinae: Loricariidae) from Rio Corrente, upper Rio Paraná basin, Brazil, Zootaxa 4483 (2), pp. 317-330 : 318-323

Corumbataia lucianoi , new species

Figs. 1 , 4a ; Table 1

Holotype. MZUSP 123824, 24.0 mm SL, female, Goiás state, municipality of Aporé, Rio Corrente, upper Rio Paraná basin, 18°30’50.7”S 52°05’48.4”W, November 2017, C. Arraya, R. Devidé, B.F. Melo, G.S.C. Silva.

Paratypes. All from Brazil. AUM 71028, 4 (17.5–26.1 mm SL), collected with holotype . LBP 9570 , 15 (12.8– 25.5 mm SL), 2 c&s (21.5–23.8 mm SL) Goiás state, municipality of Mineiros, Rio Formoso, Rio Corrente drainage, upper Rio Paraná basin, 18°16’17.0”S 52°50’34.4”W, 0 5 July 2010, R. Devidé, L.H. Pereira, J.M. Henriques . LBP 9575 , 2 (22.5–23.7 mm SL), Goiás state, municipality of Aporé, Rio Corrente, upper Rio Paraná basin, 18°30’50.7”S 52°05’48.4”W, 0 6 July 2010, R. Devidé, L.H. Pereira, J.M. Henriques . LBP 25543, 6 (19.7– 22.5 mm SL), 2 c&s (17.4–24.5 mm SL), collected with holotype . MZUSP 123825 , 4 (18.9–22.2 mm SL), collected with holotype.

Diagnosis. Corumbataia lucianoi differs from all congeners by having a smaller caudal-peduncle depth, 6.8– 8.1% of SL (vs. 10.7–11.8% of SL in C. cuesta ; 9.3–11.9% of SL in C. tocantinensis ; 10.0–11.2% of SL in C. britskii ; 9.0–10.3% of SL in C. liliai ; and 10.1–13.7% of SL in C. veadeiros ). Additionally, the new species C. lucianoi differs from all congeners, except C. liliai by the presence of a broad naked area without plates or odontodes on dorsal portion of the snout (vs. absence of naked area on dorsal portion of the snout) (see Fig. 2 ). Corumbataia lucianoi differs from C. britskii , C. liliai and C. tocantinensis by having five infraorbitals plates series (vs. four infraorbitals plates series); from C. cuestae , C. liliai and C. veadeiros by having four rounded hyaline area on caudal fin, Fig. 3 (more evident in large male specimens): two smaller and more anteriorly positioned and two large and more posteriorly positioned (vs. absence of two smaller rounded hyaline area); from C. veadeiros by presence of a conspicuous tuft of enlarged odontodes on the tip of parieto-supraoccipital (vs. absence of a tuft of enlarged odontodes on the tip of parieto-supraoccipital) and by absence of two platelets at typical adipose-fin region (vs. absence). Moreover, C. lucianoi can by further distinguished from C. liliai and C. cuestae by a greater predorsal length, 41.5–44.6% of SL (vs. 45.1–50.6% of SL and 44.8–48.6% of SL, respectively); from C. britskii by a shorter preanal length, 56.4–60.1% of SL (vs. 60.1–64.4% of SL); from C. cuestae , C. tocantinensis and C. veadeiros by a shorter cleithral width, 22.4–24.9% of SL (vs. 26.7–29.3% of SL, 24.9–28.1% of SL and 25.5–29.9% of SL, respectively); from C. britskii and C. veadeiros by a shorter body width at anal-fin insertion, 10.7–13.4% of SL (vs. 14.3–17.3% of SL and 13.8–17.3% of SL, respectively); and from C. liliai by a shorter snout opercle length, 17.9–27.3% of SL (vs. 27.4–30.7% of SL in C. liliai ).

Description. Morphometric and meristic data summarized in Table 1. Small-sized loricariid (19.4–25.6% of SL). Head and snout slightly rounded, snout tip pointed anteriorly. Snout elongated (51.3–64.0% of HL); anterior region slightly depressed. Area around snout tip without odontodes. Nostril small, almost reaching same diameter as eyes. Dorsal profile of head ascending approximately 45° to parieto-supraoccipital; slightly concavity between nostrils. Eyes relatively small (14.4–21.9% of HL), dorsolaterally positioned, just posterior of midpoint of head. Iris operculum present and well developed, almost covering eye entirely. Superior margin of orbits not elevated. Presence of inconspicuous odontodes on suboperculum. Mouth moderated in size; oral disk ellipsoid with papillae randomly distributed. Lips without odontodes; lower lip larger than upper lip, not reaching cleithrum; its border fringed; lower lip inner surface covered with small papillae, similar in size. Maxillary barbel adnate to lower lip. Teeth slender with two symmetrical cusps; central cusp larger than lateral cusps. Premaxillary teeth 18–33 (mode 22). Dentary teeth 15–29 (mode 22).

Lower surface of head naked. Head lacking ridges. Parieto-supraoccipital process elevated and with conspicuous tuft of odontodes in specimens of all size. Predorsal region without ridges. In dorsal view, body elongated and compressed on caudal peduncle. Greatest body width at cleithral region (22.4–24.9% of SL), progressively narrowing anteriorly towards snout tip and posteriorly towards caudal-fin. Dorsal profile of head and trunk covered by dermal plates, except by a naked area around dorsal-fin insertion, just behind of parietosupraoccipital. In lateral view, body depressed and convex in shape from snout tip to posterior margin of parietosupraoccipital; slight concave from that point to dorsal-fin origin; slightly concave and descending from dorsal-fin origin to first upper procurrent caudal-fin ray, elevating posteriorly to insertion of caudal fin. Greatest body depth at unbranched dorsal-fin ray insertion. Cleithrum and coracoid exposed in ventral view, covered by odontodes. Arrector fossa almost completely enclosed by ventral lamina of coracoid.

In lateral view, ventral profile straight and descending from snout tip to opercular region; slightly convex from opercular region to anal-fin origin; slightly concave from that point to lower procurrent caudal-fin ray origin. Lateral surface of body entirely covered by plates; mid-dorsal plate series truncated, (16 plates) not reaching posterior end of caudal peduncle; Lateral plates series formed by 21–23 plates (mode 22). Lateral line incomplete, with gap in line of pores along mid-length of body. Mid-ventral series of lateral plates developed and almost reaching middle of caudal peduncle (17 plates). Body plates covered with minute odontodes.

Ventral portion of body totally covered by plates, except on posterior area of parieto-supraoccipital, on ventral portion of head, on small are near nostril, around pectoral- and pelvic fins insertions, and at urogenital opening. Abdomen in adult specimens completely covered with small rounded platelets.

Dorsal-fin rays ii,7; dorsal-fin origin slightly posterior through pelvic-fin origin. Dorsal-fin unbranched ray slightly convex. Tip of adpressed dorsal-fin rays suprassing anal fin unbranched ray insertion. Dorsal-fin spinelet small and rounded. Pectoral-fin rays i,6; its tip passing adpressed pelvic-fin ray insertion reaching. Pectoral-fin axillary slit small, but present above pectoral-fin insertion. Pelvic-fin rays i,5; its distal margin straight to slightly convex; tip of adpressed pelvic-fin ray reaching anal-fin origin in males, but not in females. Absent of adipose fin. Anal-fin rays i,5; distal margin slightly convex. Caudal-fin rays i,7–7,i; slightly emarginated; unbranched rays of same size. Rays of all fins covered with pointed odontodes. Lower body depth at caudal peduncle. Caudal peduncle ellipsoid in cross section, rounded dorsally and ventrally. Compound hypurals 1–2 completely fused to compound hypurals 3–5. Total vertebrae 27 (3 c&s).

Neurocranium presented in figure 2. In dorsal view ( Fig. 2c ), parieto-supraoccipital (soc) octagonal, bordered by compound pterotic (cpt) and sphenotic (sp) laterally and by frontal (f) anteriorly. Snout composed by two rostral triangular-shaped plates (r); nine prenasal rounded-shape plates (pn) between nares, and two reduced nasal plates (n). Upper region of neurocranium composed by largest bones of head: parieto-supraoccipital (soc), frontals (f) and compound pterotics (cpt).

In lateral view ( Fig. 2d ), three posterior rostrum plates: pr1 smallest, rectangular-shaped; pr2 largest, rectangular-shaped; and pr3 median-size, square-shaped. Infraorbital plate series complete (io1–io5), io1, io2 and io3 largest; io4 and io5 smallest, forming inferior orbital margin of eyes. Opercular series complete, preopercle (pop), elongated and rectangular-shaped, covered by laterosensory canal; opercle (op) rounded; one subocular cheek plates, cp1 triangular shaped; bordering by preopercle (pop) and opercle (op), forming posterior lateral margin of head.

Color in alcohol. Background color of dorsal region of head and trunk brown. Four almost inconspicuous dark brown saddles along dorsal portion of body: first at dorsal-fin origin, second at end of dorsal-fin base, third at middle of caudal peduncle, and fourth reaching anteriormost caudal procurrent ray. Unpigmented portion of snout appears as two hyaline parallel stripes from rostral plate to nares. Mid-lateral dark brown stripe extending from tip of snout to caudal peduncle. Ventral portion of body almost entirely yellowish, except for dark, randomly distributed chromatophores and for a concentration of chromatophores at anal-fin origin. Dorsal, pectoral, and pelvic fins with dark, irregularly distributed chromatophores. Caudal-fin brown, with two smaller rounded hyaline area anteriorly, and two large rounded hyaline area posteriorly ( Fig. 1 ).

Color in life. Similar pattern described for alcohol individuals, with lighter background ( Fig. 4a ).

Sexual dimorphism. Adult males with papilla covering urogenital opening, long pelvic fin that extends beyond anal-fin origin, and unbranched pelvic-fin ray supporting dermal flap along its dorsal surface. All these features absent in all analyzed females.

Distribution and habitat. Corumbataia lucianoi is known from the Rio Corrente and Rio Formoso, both in the upper Rio Paraná basin ( Fig. 5 ). The new species was found associated with marginal vegetation (see Fig. 6 for habitat where the new species lives).

Etymology. The specific name “ lucianoi ” is in honor of Luciano de Souza da Costa e Silva, GSC Silva’s brother.

Figures

FIGURE 1. Corumbataia lucianoi, MZUSP 123824., 24.0 mm SL, female, holotype, from Goiás state, municipality of Aporé, Rio Corrente, upper Rio Paraná basin, 18°30’50.5”S 52°05’34.8”W.

FIGURE 2. Neurocranium. Yellow color indicates the naked areas around the snout plates. Corumbataia britskii, LBP 9590, a) dorsal view, b) lateral view. Corumbataia lucianoi, LBP 25543., paratype, c) dorsal view, d) lateral view. Corumbataia liliai, LBP 25544., paratype, e) dorsal view, f) lateral view.

FIGURE 3. a) C. lucianoi, MZUSP 123824., 24.0 mm SL; b) C. cuestae, LBP 8114, 27.3 mm SL; c) C. liliai, MZUSP 123826., 24.7 mm SL; d) C. veadeiros, LBP 19470, 32.6 mm SL; e) C. britskii, LBP 9590, 25.5 mm SL; f) C. tocantinensis, LBP 1653, 24.6 mm SL.

FIGURE 4. Live specimens: a) Corumbataia lucianoi, holotype, MZUSP 123824., 24.0 mm SL, female. b) Corumbataia liliai, holotype, MZUSP 123826., 24.7 mm SL, female.

FIGURE 5. Map showing the distribution of C. lucianoi at Rio Corrente (triangle = type locality) and at Rio Formoso (star = paratype locality), and Corumbataia liliai at Córrego da Cachoeira (circle = type locality).

FIGURE 6. Upper picture showing the habitat of the type locality where the species Corumbataia lucianoi lives at Rio Corrente, 18°30’50.57”S 52°05’34.89”W. Lower picture showing the habitat of the type locality where the species C. liliai lives at Córrego da Cachoeira, 18°34’50.8”S 52°05’52.8” W. Both species were found associated with marginal vegetation.