Pareiorhina rosai Silva, Roxo & Oyakawa, 2016, sp. n.
Creators: name: Silva, Gabriel S. C.
name: Roxo, Fábio F.
name: Oyakawa, Osvaldo T.
Publisher: name: Zenodo
Year: 2016
Subjects: Biodiversity
Taxonomy
Animalia
Chordata
Actinopterygii
Siluriformes
Loricariidae
Pareiorhina
Pareiorhina rosai

description: Pareiorhina rosai, sp. n.
Fig. 1; Table 1
Holotype. MZUSP 118120, male, 47.3 mm SL, Brazil, Minas Gerais State, municipality of Congonhas, unknown river, tributary of rio Maranhão, rio Paraopeba, rio São Francisco basin, 20°26'39.6"S 43°53'24.5"W, 10 March 2014, coll. Pereira GA.
Paratypes. All from Brazil, Minas Gerais State, rio São Francisco basin (51 specimens). LBP 19656 (7 males, 37.6–42.0 mm SL, 6 females, 30.1–37.9 mm SL, 1 c&s, 38.4 mm SL, sex not determined), collected with holotype. LBP 6497 (1 male, 29.2 mm SL, 1 female, 30.7 mm SL), municipality of Brumadinho, unknown river, tributary of Rio das Velhas, 20°05'47.8"S 44°02'32.9"W, 17 June 2008, coll. Teixeira RAS, Silva GJC, Ferreira AT, Henriques JM. LBP 6536 (3 males, 33.3– 29.5 mm SL, 1 male c&s, 31.4 mm SL, 15 females, 23.4–30.7 mm SL, 1 female c&s, 28.2 mm SL), municipality of Brumadinho, unknown river, tributary of Rio das Velhas, 20°00'37.1"S 43°58'8.3"W, 19 June 2008, coll. Teixeira RAS, Silva GJC, Ferreira AT, Henriques JM. LBP 16299 (1 male c&s, 30.3 mm SL, 7 females, 20.4–28.4 mm SL, 1 female c&s, 28.0 mm SL), unknown river, tributary of rio Paraopeba, municipality of Nova Lima, 20°06'04.9"S 43°52'39.5"W, 12 June 2012, coll. Mehanna M, Ferreira AT, Devidé R, Ramirez RS. MZUSP 118121 (3 males, 40.2–41.4 mm SL, 1 female, 39.4 mm SL), collected with holotype. NUP 17759 (1 male, 37.2 mm SL, 1 female, 29.8 mm SL), collected with holotype.
Diagnosis. Pareiorhina rosai can be distinguished from all congeners, except P. brachyrhyncha by having the dorsal surface of the caudal peduncle strongly concave (vs. a caudal peduncle flat in P. rudolphi, slightly concave in P. cepta and P. pelicicei, and slightly concave with a ridge in P. carrancas and P. hyptiorhachis). Additionally, the new species can be further distinguished from P. carrancas, P. hyptiorhachis, P. pelicicei and P. rudolphi by having 30 vertebrae (vs. 29 in P. hyptiorhachis and P. pelicicei, and 31 in P. carrancas and P. rudolphi); from P. rudolphi, P. carrancas and P. hyptiorhachis by having bicuspid teeth (vs. unicuspid teeth, both in premaxilla and dentary); from P. ce p t a and P. pelicicei by having a conspicuous cylindrically-shaped papilla between the oral valve and premaxilla, Fig. 2A (vs. a V -shaped papilla, Fig. 2 B); from P. cepta by having smaller odontodes along the snout margin, Fig. 3 (vs. larger odontodes along the snout margin); from P. brachyrhyncha, P. cepta, P. hyptiorhachis and P. pelicicei by having a smaller orbital diameter, 7.5–10.0% of HL (vs. 10.7–14.1% of HL in P. brachyrhyncha; 10.7–14.8% of HL in P. cepta; 11.1–15.5% of HL in P. hyptiorhachis; 10.5–14.9% of HL in P. pelicicei); from P. cepta and P. rudolphi by having a higher head width, 93.8–103.8% of HL (vs. 83.4–90.5% of HL in P. cepta; 65.5–82.1% of HL in P. rudolphi); from P. brachyrhyncha by having a shorter interorbital width, 29.3–36.9% of HL (vs. 37.1–41.9% of HL), a shorter predorsal length, 36.6–44.9% of SL (vs. 45.6–48.9% of SL), a shorter cleithral width, 27.9–31.3% of SL (vs. 31.9–36.9 of SL) and a shorter caudal peduncle depth, 7.2–8.5% of SL (vs. 8.9–10.7% of SL).P. rosai,P.rosai,10P.rosai,, n=6HolotypeRangeMeanSDRangeMeanSDRangeMeanSDSL47.3 36.5‾47.3 40.2 3.2 37.3‾47.3 41.7 3.1 36.5‾39.7 37.6 1.2Percents of SLPredοrsal length 42.4 36.6‾44.9 42.9 2.0 36.6‾44.8 42.5 2.2 41.1‾44.9 43.6 1.4 Preanal length 58.8 55.6‾62.4 59.5 1.6 58.0‾61.3 59.4 0.9 55.6‾62.4 59.7 2.4 Head length 30.3 29.5‾33.6 31.0 1.0 29.5‾33.6 30.9 1.3 30.7‾31.8 31.3 0.4 Cleithral width 28.5 27.9‾31.3 29.7 1.0 27.9‾31.3 29.5 1.0 28.1‾31.3 30.1 1.1 Dοrsal-fin unbranched ray length 21.5 20.8‾25.3 22.6 1.2 20.8‾25.3 22.4 1.4 22.1‾24.0 22.9 0.8 Base οf dοrsal fin length 15.7 14.5‾19.0 16.8 1.2 14.5‾19.0 16.5 1.3 15.6‾18.1 17.2 0.8 Τhοrax length 13.4 13.2‾17.1 14.8 1.2 13.2‾17.1 14.8 1.3 13.2‾16.0 14.8 1.1 Pectοral-fin unbranched ray length 21.1 21.1‾25.9 23.5 1.3 21.1‾25.9 23.1 1.5 22.8‾25.0 24.1 0.8 Abdοmen length 24.3 22.6‾27.0 24.7 1.0 22.6‾26.4 24.4 0.9 23.8‾27.0 25.3 1.1 Pelvic-fin unbranched ray length 22.9 20.3‾25.2 22.1 1.2 21.3‾25.2 22.7 1.1 20.3‾22.5 21.1 0.8 Anal-fin length 15.1 12.6‾18.2 15.9 1.4 12.6‾18.2 16.0 1.5 14.1‾17.8 15.9 1.2 ventral unbranched caudal ray 23.0 19.1‾25.6 22.9 1.5 19.1‾24.4 22.6 1.4 20.8‾25.6 23.3 1.6 Caudal-peduncle depth 7.2 7.2‾8.5 7.9 0.3 7.2‾8.5 7.9 0.4 7.5‾8.5 7.9 0.3 Pοstanal length 37.1 32.8‾38.5 35.7 1.6 34.4‾38.3 35.7 1.4 32.8‾38.5 35.6 2.1 Anal width 13.8 12.2‾14.0 13.1 0.5 12.2‾14.0 13.2 0.5 12.7‾13.7 13.1 0.3Percents of HLHead width 99.5 93.8‾103.8 97.0 2.5 93.8‾103.8 97.7 2.8 93.8‾98.7 95.9 1.7 Head depth 65.7 63.2‾75.2 68.3 2.6 63.2‾75.2 67.8 3.2 68.1‾69.9 69.3 0.7 Snοut length 60.7 54.9‾61.1 59.0 1.7 57.8‾61.1 59.8 1.1 54.9‾60.3 57.7 1.9 Interοrbital width 32.4 29.3‾36.9 34.1 1.9 31.7‾36.3 34.1 1.5 29.3‾36.9 34.0 2.5 Οrbital diameter 7.5 7.5‾10.0 8.5 0.6 7.5‾10.0 8.5 0.7 8.1‾9.5 8.6 0.4 Subοrbital depth 35.3 30.7‾36.5 33.7 1.6 32.8‾36.5 34.5 1.1 30.7‾34.6 32.4 1.6 Mandibular ramus 19.0 15.2‾20.7 18.2 1.2 15.2‾19.1 18.0 1.2 17.1‾20.7 18.3 1.2Other PercentsAnal width⁄cleithral width 48.6 41.5‾48.6 44.3 2.3 41.5‾48.6 44.8 2.6 42.4‾45.3 43.5 1.3 IΟ⁄ΟD 23.1 21.5‾32.5 25.4 2.5 21.5‾29.6 25.0 2.1 23.1‾32.5 25.5 3.4 IΟ⁄Mandibulary ramus 58.5 44.0‾60.5 53.4 4.6 44.0‾58.5 53.0 4.6 48.8‾60.5 54.1 4.8 PDS length⁄first dοrsal ray length 50.8 47.1‾61.5 52.7 3.6 47.1‾61.5 52.8 4.3 49.4‾55.2 52.5 2.1 CP length⁄CP depth 19.4 19.2‾26.1 22.2 1.7 19.2‾24.6 22.1 1.6 20.6‾26.1 22.3 2.0 Pelvic-fin length⁄CP depth 31.4 31.5‾39.2 35.7 2.3 31.4‾38.3 34.7 2.2 35.8‾39.2 37.5 1.3 Lοwer caudal spine⁄CP depth 31.3 31.2‾38.2 34.6 2.2 31.3‾37.9 34.9 2.0 31.2‾38.2 34.0 2.6MeristicsHolotypeRangeModeSDRangeModeSDRangeModeSDDοrsal plates 24 24‾25 25 ‾ 24‾25 25 ‾ 24‾25 24 ‾ Mid-dοrsal plates 17 15‾20 18 ‾ 16‾18 18 ‾ 15‾20 18 ‾ Median plates 27 24‾27 25 ‾ 25‾27 26 ‾ 24‾27 25 ‾ Mid-ventral plates 20 19‾22 20 ‾ 19‾22 20 ‾ 19‾22 19 ‾ ventral plates 21 19‾21 21 ‾ 20‾21 21 ‾ 19‾21 21 ‾ Premaxillary teeth 27 26‾48 42 ‾ 26‾46 37 ‾ 40‾48 40 ‾ Dentary teeth 24 22‾38 32 ‾ 22‾35 34 ‾ 28‾38 32 ‾ n= 16 Males, n= Females
Description. Morphometric and meristic data are available in Table 1. Small size loricariids. In lateral view, dorsal profile of body convex from tip of snout to dorsal-fin origin, almost straight and descending from this point to caudal-fin base. Ventral profile straight from snout tip to caudal-fin base. Greatest body depth at dorsal-fin origin. Body progressively narrowing posteriorly from cleithrum to snout tip and to caudal peduncle. Trunk and caudal peduncle trapezoid in cross-section. Postdorsal region of trunk strongly concave formed by a pair of parallel and elevated series of plates.
Head flat to slightly convex between orbits; dorsal margin of orbits elevated. Head without crests even in juveniles. Eye small, situated dorsolaterally just posterior of midpoint of head. Snout tip rounded in dorsal view. Rostral margin of snout with posteriorly-directed odontodes; numerous conspicuous odontodes on dorsal portion of head. Perforations of compound pterotic distributed on whole bone, greater and more concentrated on its ventral margin. Nasal apertures small. Iris operculum present and developed. Mouth wide; oral disk roundish with papillae uniformly distributed on base of dentary and premaxilla; papillae decreasing in size distally. Roof of oral cavity with two or three thin fold of tissue transversally oriented and a conspicuous cylindrical shaped papilla between oral valve and premaxilla. Lower lip larger than upper, not reaching pectoral bridge; its border fringed. Maxillary barbel very short, absent in some specimens. Teeth slender, bicuspidate with long mesial crown and minute lateral cusp. Premaxillary teeth 26–48 [mode 42]. Dentary teeth 22–38 [mode 32].
Dorsal fin ii,7; dorsal-fin spinelet short and ovoid shaped; locking mechanism not functional. Tip of unbranched dorsal-fin rays slightly surpassing end of anal-fin base. Pectoral fin i,6; its unbranched ray almost reaching middle of pelvic fins. Pectoral and pelvic-fins unbranched ray covered with conspicuously pointed odontodes, largest at ventral portion. Pelvic fin i,5; its unbranched ray slightly curved inward. Pelvic-fin ventral region odontodes bent and slightly turned mesially. Adipose fin absent. Anal fin i,5; distal margin slightly convex. Caudal-fin rays i,7-7,i, its posterior margin truncated. Body covered with bony plates, except in ventral portions of head, region overlaying swim bladder capsule, large portions of abdomen and around pectoral and pelvic-fins insertions. Two platelets with odontodes embedded in skin over arrector fossae and next to pectoral-fin insertion and a large bone plates covered with odontodes next to pectoral-fin insertion.
Dorsal plates series 24–25 [mode 25], first positioned just posterior to supraoccipital, last plate contacting first dorsal caudal-fin procurrent ray, mid-dorsal plates series 15–20 [mode 18], first located laterally to first plate of dorsal series, last laterally to plate nineteen of dorsal series, median plates series 24–27 [mode 25], plates bearing lateral-line canal. Mid-ventral plates series 19–22 [mode 20], first contacting posterior portion of cleithrum, last laterally to plate twenty of median series. Ventral plates series 19–21 [mode 21], first just above pelvic-fin insertion, last one contacting first ventral caudal-fin procurrent ray. Total vertebrae 30 (5 c&s specimens).
Color in alcohol. Ground color of dorsum and lateral surface of body pale ochre. Ventral surface light gray. Some specimens with three black transverse bars on dorsal surface of trunk, first at base of dorsal fin, second in middle of caudal peduncle and last at base of caudal fin (this character is not visible in holotype); these bars merging with black longitudinal stripe along middle of body. Ventral surface of body scattered with small chromatophores. All fins with irregularly and poorly defined bars: three on anal fin, four on pectoral and pelvic fins, and five on dorsal fin. Base of anal fin surrounded by a concentration of black and small chromatophores. Caudal fin completely dark with two lighter bars (see Fig. 1).
Color in life. Similar pattern of alcohol specimens, but with background color light brown (see Fig. 4).
Sexual dimorphism. Adult males of Pareiorhina rosai possess three characters that clearly distinguish them from females: (1) presence of a papilla at urogenital opening; (2) unbranched pelvic-fin ray supporting a dermal flap on proximal dorsal surface, slightly wider in basal portion and progressively narrowing distally; and (3) pelvicfin extending beyond anal-fin origin (pelvic fin far from reaching anal-fin origin in females).
Distribution. The new species is only known from four small streams with unknown names of the rio São Francisco basin: one tributary of rio Maranhão (type locality), one tributary of rio Paraopeba and two tributaries of Rio das Velhas (Fig. 5).
Habitat. Pareiorhina rosai is found in fast-flowing stream water associated with rocks and sand in the bottom of the rivers. In large portions of the tributary of rio Maranhão, where the new species was found, the forest is well preserved, and the penetration of light was scarce because of the marginal vegetation with large trees (Fig. 6).
Etymology. The specific name, rosai, is a patronym that honors João Guimarães Rosa the famous Brazilian writer who documented the history of people living near the Rio das Velhas and rio Paraopeba (e.g. Sagarana and Grande Sertão Veredas), in the Brazilian Savanna (“sertão”) in Bahia, Goiás and Minas Gerais States.
description: Published as part of Silva, Gabriel S. C., Roxo, Fábio F. & Oyakawa, Osvaldo T., 2016, Description of a new species of Pareiorhina (Siluriformes: Loricariidae) from the rio São Francisco basin, Brazil, pp. 381-391 in Zootaxa 4107 (3) on pages 382-386, DOI: 10.11646/zootaxa.4107.3.6, http://zenodo.org/record/261285