Parotocinclus fluminense, Roxo, Fábio F., Melo, Bruno F., Silva, Gabriel S. C. & Oliveira, Claudio, 2017

Roxo, Fábio F., Melo, Bruno F., Silva, Gabriel S. C. & Oliveira, Claudio, 2017, New species of Parotocinclus (Siluriformes: Loricariidae) from coastal drainages of Rio de Janeiro, southeastern Brazil, Zootaxa 4232 (2), pp. 260-270 : 261-265

Parotocinclus fluminense , new species

( Fig. 1 , Table 1 )

Holotype. MZUSP 120989 , male, 27.7 mm SL, Brazil, Rio de Janeiro, municipality of Casemiro de Abreu, rio Branco, tributary of rio São João , coastal drainage, 22°27’04”S 42°05’04”W , May 2016, D. Freitas-Souza, & F.P. Lima.

Paratypes. All from Rio de Janeiro, Brazil (124 total paratypes): ANSP 200535, 4 , 19.5–25.0 mm SL, municipality of Silva Jardim , rio Ouro, rio São João, 22°34’22”S 42°28’17”W, May 2016, D. Freitas-Souza & F.P. Lima . AUM 67842, 4 , 22.2–31.1 mm SL, municipality of Silva Jardim , rio Ouro, rio São João, 22°34’22”S 42°28’17”W, May 2016, D. Freitas-Souza & F.P. Lima . LBP 18474, 16, 25.2–35.5 mm SL, municipality of Silva Jardim , córrego Bananeiras, tributary of rio São João, 22°28’51”S 42°23’39”W, Nov. 2013, R. Devidé, G.J.C. Silva, P.C. Scacchetti & R. Utsunomia . LBP 21948, 7, 21.9–27.0 mm SL, 2 c&s, 25.3–25.4 mm SL, same data as holotype . LBP 21999, 8, 16.7–26.2 mm SL, 2 c&s, 23.1–30.2 mm SL, municipality of Silva Jardim , rio Maratuã, rio São João, 22°31’40”S 42°21’25”W, May 2016, D. Freitas-Souza & F.P. Lima . LBP 22037, 9, 16.3–31.0 mm SL, 2 c&s, 27.1–32.1 mm SL, municipality of Silva Jardim , rio Ouro, rio São João, 22°34’22”S 42°28’17”W, May 2016, D. Freitas-Souza & F.P. Lima . LBP 22061, 3, 23.1–30.3 mm SL, municipality of Varginha , rio Capivari, rio São João, 22°38’23”S 42°28’16”W, May 2016, D. Freitas-Souza & F.P. Lima . LBP 22080, 7, 21.0– 29.1 mm SL, municipality of Rio Bonito , rio Bacaxá, rio São João, 22°41’34”S 42°33’12”W, May 2016, D. Freitas-Souza & F.P. Lima . LBP 22279, 18, 21.9–35.8 mm SL, municipality of Silva Jardim , rio São João, 22°32’40”S 42°27’52”W, Aug. 2016, D. Freitas-Souza & F.P. Lima . LBP 22280, 18, 25.3–33.3 mm SL, municipality of Silva Jardim , rio Bacaxá, rio São João, 22°41’34”S 42°33’12”W, Aug. 2016, D. Freitas-Souza & F.P. Lima . LBP 22281, 4, 18.9– 26.6 mm SL, municipality of Casemiro de Abreu , rio Ibiabas, tributary of rio São João, 22°28’38”S 42°14’48”W, Aug. 2016, D. Freitas-Souza & F.P. Lima . LBP 22282, 1, 26.4 mm SL, municipality of Casemiro de Abreu , rio Lontras, tributary of rio São João, 22°28’31”S 42°09’01”W, Aug. 2016, D. Freitas-Souza & F.P. Lima . LBP 22283, 6, 22.1–34.1 mm SL, municipality of Silva Jardim , rio Maratuã, tributary of rio São João, 22°31’40”S 42°21’25”W, Aug. 2016, D. Freitas-Souza & F.P. Lima . LBP 22284, 1, 23.4 mm SL, municipality of Silva Jardim , rio Imbaé, tributary of rio São João, 22°38’13”S 42°27’35”W, Aug. 2016, D. Freitas-Souza & F.P. Lima . LBP 22285, 1, 22.9 mm SL, municipality of Silva Jardim , rio Aldeia, tributary of rio São João, 22°29’17”S 42°16’14”W, Aug. 2016, D. Freitas-Souza & F.P. Lima . MCP 50865, 4 , 24.7–31.9 mm SL, municipality of Rio Bonito , rio Bacaxá, tributary of rio São João, coastal drainage, 22°41’34”S 42°33’12”W, May 2016, D. Freitas- Souza & F.P. Lima. MZUSP 120990, 3 , 21.4–26.2 mm SL, same data as holotype . NUP 18791, 4, 24.9–33.1 mm SL, municipality of Rio Bonito , rio Bacaxá, rio São João, 22°41’34”S 42°33’12”W, May 2016, D. Freitas-Souza & F.P. Lima.

Diagnosis. Parotocinclus fluminense can be distinguished from all congeners, except P. amazonensis Garavello, 1977 , P. bidentatus , P. britskii , P. dani Roxo, Silva & Oliveira, 2016 , P. eppleyi , P. longirostris Garavello, 1988 , P. polyochrus Schaefer, 1988 and P. variola Lehmann A., Schvambach & Reis, 2015 by the presence of a triangular patch of dark pigmentation at the anterior portion of the dorsal-fin base (vs. absence of a triangular dark blotch). Additionally, P. fluminense differs from P. bidentatus , P. dani , P. halbothi Lehmann A., Lazzarotto & Reis, 2014 , P. muriaensis , P. seridoensis Ramos, Barros-Neto, Britski & Lima, 2013 and P. spilurus ( Fowler, 1941) by the presence of a fully developed adipose fin (vs. absent or poorly developed adipose fin); it differs from P. cearensis Garavello, 1977 , P. cesarpintoi , P. jumbo Britski & Garavello, 2002 , P. prata Ribeiro, Melo & Pereira, 2002 , P. robustus Lehmann A. & Reis, 2012 , P. spilosoma ( Fowler, 1941) and P. spilurus by possessing a total exposure of the ventral surface of the pectoral girdle ( Fig. 2 a) (vs. ventral exposure restricted to a small lateral portion of the girdle and covered medially by a skin, Fig. 2 b); it differs from P. amazonensis , P. arandai , P. britskii , P. collinsae Schmidt & Ferraris, 1985 , P. eppleyi , P. halbothi , P. longirostris , P. polyochrus , P. prata , P. robustus , P. spilurus , P. seridoensis and P. variola , by the distinctive pigmentation pattern of the caudal fin, which has a hyaline background with a large black stain covering the anterior portion of the caudal fin, tapering irregularly through the distal portion of the ventral lobe that results in a hyaline rounded area, and a small patch of dark pigmentation on distal portions of the dorsal lobe (vs. absence of such pigmentation pattern).

Description. Morphometric data presented in Table 1 . Body relatively small. Dorsal profile slightly convex from snout tip to dorsal-fin origin; straight from this point to end of caudal peduncle. Ventral profile straight to slightly convex from tip of snout to anal-fin insertion, then slightly concave to lower caudal-fin spine insertion. Maximum body depth at dorsal-fin origin. In dorsal view, largest body width at cleithrum progressively narrowing towards snout tip and caudal peduncle. Cross-section of body between pectoral- and pelvic-fin insertions rounded dorsally and laterally, ventrally flat. Cross-section of caudal peduncle ellipsoid.

Supraorbital elevated. Orbital diameter moderately small with orbits positioned dorsolaterally. Snout moderately long and rounded in dorsal view. Nares small, apparently slightly larger in males than in females. Odontodes evenly distributed covering body and head plates. Odontodes in snout margin larger than those of head. Absence of tufts of hypertrophied odontodes at posterior medial portion of parieto-supraoccipital and crests on head. Lips moderately developed and rounded; lower lip not reaching pectoral girdle. Lower lip twice as large as upper lip. Papillae uniformly distributed on base of lips, decreasing in size distally. Maxillary barbel present and poorly developed, one quarter lower lip length. Teeth slender and bicuspid; medial cusp larger than lateral cusps. Second series of unicuspid teeth present in juveniles (specimens smaller than 23.5 mm SL). Left premaxillary bicuspid teeth 18¯31 (mode 26). Left dentary bicuspid teeth 17¯27 (mode 25).

Dorsal-fin rays ii,7; its origin posterior to pelvic-fin origin; dorsal-fin unbranched ray slightly convex, with its distal portion surpassing vertical line through last anal-fin branched ray insertion. Dorsal-fin spinelet laterally extended, V -shaped, and dorsal-fin locking mechanism functional. Pectoral-fin rays i,6; tip of longest pectoral-fin ray (first branched ray) reaching beyond vertical line through center of pelvic-fin length when adpressed. Pectoral axial slit present between pectoral-fin base and lateral process of cleithrum. Lateral and ventral margins of pectoral spine possessing odontodes increasing in size posteriorly. Pelvic-fin rays i,5; tip exceeding anal-fin unbranched ray insertion when adpressed; ventral margin possessing odontodes increasing in size posteriorly. Males with flap along dorsal margin of unbranched pelvic-fin ray, absent in females. Anal-fin rays i,5; tip of unbranched anal-fin ray reaching seventh to eighth plate from anal-fin origin. Adipose fin present and well developed with membrane in ventral portion of the spine. Adipose fin preceded by one median, azygous plate. Caudal-fin rays i,14,i; distal margin forked.

Lateral plate series formed by 21¯26 (mode 24) plates. Lateral line complete, without gaps along perforated plates, terminating in zero or two unperforated plates. Abdomen partially covered by dermal plates; naked areas between median and lateral plate series. Cleithrum partially enclosed by ventral lamina of coracoid.

Color in alcohol. Ground coloration of dorsal surface of head and body dark and gray, same color pattern in adults and juveniles. Ventral surface light brown to yellow. All body and fins scattered by dark chromatophores, more so on dorsal and lateral portions of body. Orbital margin slightly brighter dorsally. Lateral surface of body covered by a wide black strip extending along lateral line, from snout tip to anterior margin of caudal fin. Dorsal portion of snout delineated by two hyaline stripes from its tip to nares. Four transverse light bands along dorsal surface of body, one located at caudal-fin origin, one posteriorly to adipose fin, one posteriorly to dorsal-fin origin, and one covering a large area around dorsal-fin origin. Dorsal, pectoral, pelvic, and anal fins with irregular series of dark spots on rays, sometimes forming stripes, more so on pectoral-fin rays. Anterior portion of the dorsal-fin membrane with a triangular patch of dark pigmentation. Anteroventral portion of the caudal fin with a distinctive dark mark extending irregularly through distal portions of the ventral lobe, with hyaline rounded area. Small patch of dark pigmentation on distal portions of dorsal-fin lobe ( Fig. 1 ).

Sexual dimorphism. Males have papilla at urogenital opening (vs. papilla absent in females) and unbranched pelvic-fin ray supporting dermal flap along ventral surface (vs. dermal flap absent in females). Nares apparently larger in males.

Distribution. Parotocinclus fluminense are so far known from nine small tributaries of rio São João (rio Aldeia, rio Bacaxá, rio Branco, rio Capivari, rio Ibiabas, rio Imbaé, rio Lontras, rio Maratuã, and rio Ouro) a coastal river flowing directly to Atlantic Ocean, state of Rio de Janeiro, southeastern of Brazil ( Fig. 3 ).

Habitat. Parotocinclus fluminense was found associated with marginal submerged vegetation that covers the bottom and the border of the headwaters in moderate flowing sections of the rivers. The region has suffered high anthropic influence, such as cattle and agriculture. Penetration of light is intense due marginal erosion ( Fig. 4 ).

Etymology. From Latin flumine = river; and ense = natural, in allusion to the Baixada Fluminense , relative to the area surrounding the city of Rio de Janeiro in which Parotocinclus fluminense inhabits and, consequently, in honor to the population from the state of Rio de Janeiro, popularly named fluminense . A noun in apposition.

Figures

FIGURE 1. Parotocinclus fluminense, MZUSP 120989, holotype, 27.7 mm SL, Brazil, Rio de Janeiro, municipality of Casemiro de Abreu, rio Branco, tributary of rio São João, eastern coastal drainage.

FIGURE 2. (a) Ventral view of Parotocinclus fluminense, MZUSP 120989, holotype, showing the total exposure of the pectoral girdle; (b) Ventral view of P. prata, MZUSP 68359, holotype, showing the pectoral girdle covered by a skin. Photo (b): C. H. Zawadzki.

FIGURE 3. Map of eastern Rio de Janeiro in southeastern Brazil, showing the distribution of Parotocinclus fluminense. Star represents holotype and circles represent paratypes. Light gray in the map delimits the rio São João basin.

FIGURE 4. Rio Branco, tributary of rio São João, type locality of Parotocinclus fluminense, municipality of Casemiro de Abreu, Rio de Janeiro. Photo: D. Freitas-Souza & F. P. Lima.

Tables

TABLE 1. Morphometric data of Parotocinclus fluminense (holotype and 21 paratypes). SD = standard deviation.

	Holotype	Range	Mean	SD
Standard Length (mm)	27.7	23.5‾30.8	27.0
Percent SL
Predorsal length	45.8	44.6‾49.8	46.9	1.4
Preanal length	62.4	60.2‾66.0	62.9	1.6
Head length	35.3	33.1‾37.9	35.6	1.0
Cleithral width	25.2	22.8‾25.3	24.2	0.7
Dorsal-fin spine length	26.3	23.4‾28.0	25.5	1.3
Base of dorsal-fin length	13.0	9.5‾14.8	12.8	1.3
Thorax length	14.8	13.6‾16.8	15.3	1.0
Pectoral-fin spine length	27.8	23.9‾29.8	27.2	1.5
Abdomen length	20.5	20.5‾23.8	22.3	1.1
Pelvic-fin unbranched ray length	20.9	16.6‾22.2	19.2	1.9
Anal-fin unbranched ray length	18.7	16.0‾19.3	17.7	1.0
Ventral caudal-fin unbranched length	32.4	28.3‾35.8	31.8	1.9
Caudal peduncle depth	10.1	8.0‾10.3	9.1	0.6
Caudal peduncle length	31.7	27.2‾32.5	30.4	1.7
Anal width	12.6	11.7‾14.8	13.1	0.8
Body depth at dorsal-fin origin	15.5	13.5‾16.9	14.9	0.9
Percent head length
Head depth	39.8	38.7‾45.2	41.4	1.9
Snout length	55.1	50.5‾56.8	54.0	1.8
Interorbital width	36.7	35.6‾38.6	37.0	0.8
Orbital diameter	13.2	11.6‾16.1	13.8	1.2
Suborbital depth	14.2	14.2‾18.4	16.4	1.0
Mandibular ramus	9.1	7.1‾14.3	10.0	1.7