Pareiorhaphis scutula, a new species of neoplecostomine catfish (Siluriformes: Loricariidae) from the upper rio Doce basin, Southeastern Brazil

Pareiorhaphis scutula, a new species of neoplecostomine catfish (Siluriformes: Loricariidae) from the upper rio Doce basin, Southeastern Brazil

Edson H. L. Pereira^I; Fábio Vieira^II; Roberto E. Reis^I

^ILaboratório de Sistemática de Vertebrados, Pontifícia Universidade Católica do Rio Grande do Sul. Av. Ipiranga, 6681, 90619-900 Porto Alegre, RS, Brazil. [e-mail], [e-mail]

^IIAgência Shopping Del Rey, CP 4011, 31250-970 Belo Horizonte, MG, Brazil. [e-mail]

ABSTRACT

Pareiorhaphis scutula, new species, is described from the headwaters of the rio Piracicaba, tributary to the upper rio Doce basin in the State of Minas Gerais, southeastern Brazil. The new species is distinguished from all congeners by having an unique autapomorphic feature: the abdominal surface from pectoral girdle to pelvic-fin insertions covered with small platelets imbedded in skin and irregularly scattered. This feature is not shared with any other Pareirhaphis species. Pareiorhaphis scutula is further compared with the sympatric P. nasuta.

Key words: Neotropical, Taxonomy, Isbrueckerichthys, Pareiorhaphis nasuta, cascudo.

RESUMO

Pareiorhaphis scutula, nova espécie, é descrita das cabeceiras do rio Piracicaba, tributário do rio Doce no Estado de Minas Gerais, sudeste do Brasil. A nova espécie se distingue de todos os demais congêneres por apresentar como autapomorfia a superfície abdominal, entre as nadadeiras peitorais e a inserção das nadadeiras pélvicas, coberta por pequenas placas irregularmente arranjadas. Esse caráter não é compartilhado com nenhuma outra espécie de Pareiorhaphis. Pareiorhaphis scutula é ainda comparado com a espécie simpátrica P. nasuta.

Introduction

The last decade has witnessed a remarkable increase in our understanding about the diversity of the neoplecostomine genus Pareiorhaphis Miranda Ribeiro, 1918, with 10 of the 18 currently known species described in this period. The geographic range of the genus also suffered considerably augmentation due to the new species records. Species of Pareiorhaphis that were formerly recorded from upper rio Uruguai, coastal drainages from Santa Catarina to Rio de Janeiro, and rio Almada in Bahia are nowadays recorded from the upper reaches of rios Jacui, Uruguai, Iguaçu, and São Francisco to most of coastal basin from Rio Grande do Sul to southern Bahia. Pareiorhaphis nasuta Pereira, Vieira & Reis, 2007 was described from the upper rio Matipó basin, representing the first Pareiorhaphis species in the rio Doce drainage. In this paper we report on a second new species of Pareiorhaphis from the upper rio Piracicaba basin in the rio Doce drainage.

Material and Methods

Museum abbreviations follow Ferraris (2007). All morphometric features were measured with digital calipers to the nearest 0.1 mm and were made from point to point under a stereomicroscope. Measurements follow Pereira et al. (2007). Body plate counts and nomenclature follow the schemes of serial homology proposed by Schaefer (1997). Standard length is expressed in millimeters while all other measurements are given as percents of standard length, except for subunits of the head, which are presented as percents of the head length. Osteological preparations were cleared and counterstained for cartilage and bone (c&s) using the method of Taylor & van Dyke (1985). In the lists of examined material museum abbreviation and catalog number come first, followed by the number and SL range of specimens in that lot, the number and SL range of specimens measured for the morphometric comparisons, in parentheses, and locality. For type specimens, date of collection and collectors are also given. Abbreviations used are H (holotype), SL (standard length), and HL (head length).

Adult males of Pareiorhaphis are herein defined as specimens having distinctive modifications that involves the shape of the pectoral spine, hypertrophied odontodes along the margins of head, and fleshy lobes on lateral margins of head, although not necessarily in reproductive maturity. The other specimens included in the list of material examined are a combination of females, young males and immature specimens of both sexes.

Pareiorhaphis scutula, new species Fig. 1

Holotype. MCP 44046, 84.7 mm SL, Brazil, Minas Gerais, Nova Era, rio Doce drainage, córrego Prainha, tributary to rio Piracicaba, 19º38'54''S 42º57'37''W, 17 Aug 2007, F. Vieira & I. A. Figueiredo.

Paratypes. Brazil: Minas Gerais: rio Doce drainage: MCP 44045, 15, 21.3-67.6 mm SL (10, 51.1-67.6 mm SL); UFRGS 10820, 2, 53.0-53.7 mm SL; MNRJ 33986, 2, 47.2-53.2 mm SL; AMNH 249486, 2, 45.3-55.9 mm SL; ANSP 189490, 2, 47.9-59.5 mm SL, all collected with the holotype. MCP 37182, 27 + 2 c&s, 28.2-84.7 mm SL (6, 58.1-84.7 mm SL), Nova Era, córrego Prainha on Road to Cachoeira da Fumaça, 19º38'53''S 42º57'37''W, 9 Oct 2004, E. H. L. Pereira, R. E. Reis & P. Lehmann. MCP 28683, 10 + 1 c&s, 25.3 90.5 mm SL (7, 54.9-90.5 mm SL), Nova Era, córrego Prainha, tributary to rio Piracicaba, 19º45'S 43º03'W, Jun 2001, F. Vieira & P. S. Pompeu. MCP 38811, 3, 69.9-87.7 mm SL (3), Nova Era, córrego Prainha, tributary to rio Piracicaba, at limit between Antônio Dias and Nova Era, Aug 1998, F. Vieira & P. S. Pompeu. MCP 38810, 6 + 1 c&s, 42.5-77.1 mm SL (2, 64.3-77.1 mm SL), Nova Era, córrego Prainha, tributary to rio Piracicaba, 19º39'12''S 42º57'20''W, 28 Jul 2004, F. Vieira & I. A. Figueiredo.

Diagnosis. Pareiorhaphis scutula is uniquely diagnosed from all remaining Pareiorhaphis species by having the abdomen entirely covered with small platelets imbedded in skin and irregularly scattered from pectoral girdle to pelvic-fin insertions (vs. abdomen totally naked or with one to four small platelets on each side just posterior to gill opening in P. parmula and P. nasuta; Fig. 2). The new species can be further distinguished from P. parmula by having 51-71 premaxillary teeth (vs. 31-48), 24-28 lateral plates in the median series (vs. 28-31), and longer snout length (62.1-70.0 vs. 53.8-63.0% HL) and from P. nasuta by having a shorter snout length (62.1 70.0 vs. 71.1-75.6% HL) and a larger orbital diameter (11.9-14.8 vs. 8.6-11.3% HL; Fig. 3).

Description. Member of Neoplecostominae as diagnosed by Pereira (2009). Counts and proportional measurements in Table 1. Small to medium-sized loricariid with standard length of measured specimens 51.1-90.5 mm SL. Body elongate and moderately depressed, progressively tapering from cleithrum to end of caudal peduncle. Dorsal profile of body gently convex, rising from snout tip to origin of dorsal fin and then descending to end of caudal peduncle. Greatest body depth at dorsal-fin origin. Least body depth at shallowest part of caudal peduncle. Trunk and caudal peduncle mostly oval in cross-section, slightly flattened ventrally and more compressed caudally. Lateral-line canal in median series complete, pored tube visible from compound pterotic to caudal-fin base. Ventral profile almost straight between snout tip and pelvic girdle, slightly elevating posteriorly along analfin base, almost straight along caudal peduncle. Dorsal surface of body covered by plates except for small naked area around dorsal-fin base. Ventral surface of head, portion from pelvic-fin insertions to anal-fin origin, and portion around anal fin totally naked. Abdomen covered by small, embedded platelets, irregularly arranged from pectoral girdle to insertion of pelvic fins. Some adult males with few small platelets behind insertion of pelvic fin but never reaching to anal-fin origin.

Head broad and moderately depressed. Dorsal profile of head round in dorsal view; females and juveniles more slender. Interorbital space straight or slightly concave. Three weakly elevated ridges between orbits and snout tip. Outer ridges from middle of snout to upper margins of orbits slightly more prominent. These ridges ornamented with short hypertrophied odontodes in adult males. Snout gently convex in lateral profile; snout tip with small ovoid area of naked skin. Adult males with well-developed soft fleshy lobes extending along lateral portion of head. Soft fleshy area ornamented with short hypertrophied odontodes, approximately perpendicular to body axis. Eye small, dorsolaterally placed; orbit diameter 11.9-14.8% HL of head length. Iris operculum absent or very small. Nares ovoid, slightly longer than wide, positioned midway between snout tip and anterior orbit margin. Oral disk roughly circular. Lips well developed, occupying most of ventral surface of head. Lower lip wide and long but not reaching pectoral girdle, upper lip narrow. Lower lip densely covered by minute papillae. Papillae surrounded by small naked areas, decreasing in size towards edge. Posterior edge slightly fringed. Maxillary barbel short and united to lip by membrane basally, free distally. Both premaxillae and dentaries angled at approximately 120º, with mesial ends slightly curved inwards. Teeth slender, asymmetrically bifid, medial cusp slightly curved inwards. Lateral cusp small and pointed, almost reaching half-length of medial cusp.

Dorsal fin originating slightly anterior to vertical line passing through pelvic-fin origin. Dorsal fin short, not reaching preadipose azygous plates when adpressed. Nuchal plate exposed, not covered by skin. Dorsal-fin spinelet present but dorsal-fin locking mechanism non-functional. Dorsal-fin spinelet transversely oval-shaped, wider than base of dorsal spine. Dorsal spine moderately flexible, followed by seven branched rays. Adipose fin with well-ossified leading spine bearing odontodes. Adipose-fin membrane extended slightly beyond adipose-fin spine. Adipose fin preceded by two to four median unpaired preadipose azygous plates. Pectoral fin moderate in size, with curved and flattened unbranched ray, covered by minute odontodes in immature males and females. Adult males with pectoral-fin spine very broad; bearing straight and short hypertrophied odontodes on its entire surface. Six branched rays, first and second as long as spine. Subsequent branched rays decrease gradually in size. Posterior margin of pectoral fin slightly round, overlapping pelvic-fin origin when adpressed. Pelvic fin with one unbranched and five branched rays, not reaching anal-fin origin when adpressed. Pelvic-fin unbranched ray depressed, covered with minute odontodes ventrally and laterally; dermal flap on its dorsal surface present and well developed, extending to ray tip. Pelvic-fin flap distinctly higher near fin base. Anal fin long with one unbranched and five branched rays; passing vertical at adipose-fin origin when adpressed. Caudal fin forked or slightly concave; lower lobe slightly longer than upper; one upper unbranched, 14 branched, and one lower unbranched rays. Upper caudal-fin lobe with five and lower lobe with four or five ventral plate-like procurrent rays, posteriormost elongate. Odontodes on principal and procurrent rays small and irregularly arranged.

Color in alcohol. Ground color of dorsal surface of body and head greyish-brown, darker anteriorly; light brown to yellowish white ventrally, skin of abdomen white and lips pale yellow. Dorsum irregularly spotted with dark brown, forming three irregular and diffuse saddles located at origin of dorsal fin, behind dorsal-fin base, and at adipose fin. Skin between dermal plates darker, conferring slightly reticulate pattern, especially on ventral surface of caudal peduncle. Adult males with fleshy lobes on margin of head and pectoral-fin spines whitish-grey and yellow to orange hypertrophied odontodes. Dorsal-fin rays with 3-5 and caudal-fin rays with 4-5 dark spots forming irregular transverse bands on orange-brown background. Pectoral-, pelvic-, and anal-fin rays also spotted with dark brown on a pale yellow background, but spots not forming clear bands. Pectoral and pelvic fins whitish tan on ventral surface. Interradial membrane of all fins hyaline or pale white.

Distribution. Pareiorhaphis scutula is so far known from the córrego Prainha, a creek tributary to the rio Piracicaba in the upper reaches of the rio Doce drainage basin near Nova Era, Minas Gerais, Brazil (Fig. 4).

Habitat and ecological notes. The córrego Prainha, where most specimens of Pareiorhaphis scutula were collected, is a shallow creek (0.2-0.5 m depth and approximately 5 m wide) with rocky bottom, swift current, and clear water. Most of the creek banks are deforested and covered with grasses. Other fish species collected syntopically are Trichomycterus sp., Geophagus brasiliensis, Neoplecostomus sp., and Astyanax sp.

Sexual dimorphism. According to Pereira et al. (2007: 444) adult males of Pareiorhaphis can be recognized by having cheeks (postrostral and cheek plates) covered with hypertrophied odontodes. In addition, adult males of Pareiorhaphis scutula are also characterized by the following sexually dimorphic character: (1) Large soft fleshy lobes extending along the entire lateral margins of head. This soft fleshy area is ornamented with short hypertrophied odontodes, approximately perpendicular to the body axis. Odontodes also occur in females and juveniles, but are much smaller, while soft fleshy lobes are absent in females and juveniles. (2) Unbranched pectoral-fin ray very thick from the base to approximately three-fourths of its length, with distal portion soft and with somewhat short hypertrophied odontodes on outer and ventral surfaces. (3) Fully developed males have a well-developed flashy flap along the entire length of the dorsal margin of the pectoral-fin spine. (4) Unbranched pelvic-fin ray with developed dermal flap on dorsal surface, extending to ray tip and distinctly higher near fin base.

Etymology. The specific epithet scutula from the Latin, a diminutive of scuta, plate, scute, in allusion to the small plates that cover the abdominal region of Pareiorhaphis scutula. A noun in apposition.

Discussion

The new species is diagnosed as a member of Pareiorhaphis based on the possession of the derived features listed by Pereira et al. (2007) as diagnostic for the genus: cheeks, opercle, and the exposed lateral process of the cleithrum of adult males covered with hypertrophied odontodes, and lateroventral portion of preopercle deeply rugose due to the implantation of hypertrophied odontodes.

The most distinctive feature of Pareiorhaphis scutula, however, is the presence of small platelets irregularly scattered on the abdominal surface from pectoral girdle to pelvic-fin insertions (Fig. 2a), a feature common to the species of Isbrueckerichthys and that has not been previously reported among Pareiorhaphis species. The new species is not a member of Isbrueckerichthys, however, because its second infraorbital bone forms part of the lateral edge of nasal opening (vs. infraorbital 2 not forming the edge of the nasal opening in Isbrueckerichthys) and because it possesses a dorsal-fin spinelet (vs. dorsal-fin spinelet usually absent in Isbrueckerichthys).

Two other species of Pereiorhaphis, P. parmula and P. nasuta, share the possession of a few platelets on each side of the pectoral girdle, just posterior to the gill opening (Pereira, 2005; Pereira et al., 2007). Among these three species, P. nasuta shares with the new species four derived features, not found in other Pareiorhaphis, and are hypothesized to be sister-species. These characters are: (1) In most loricariids the lateral ethmoid forms the posterior rim of the nasal opening and is covered by skin or by dermal plates. In both P. nasuta and P. scutula the lateral ethmoid is exposed posterior to the nasal opening and support short odontodes. (2) Among neoplecostomines the interhyal articulates to the hyomandibula anteriorly, near the cartilaginous section between the hyomandibula and the quadrate. Contrarily, in P. nasuta and P. scutula the interhyal is articulated more posteriorly, near the central region of the ventral margin of the hyomandibula. (3) The articulation between the hyomandibula and the quadrate of loricariids occurs through a synchondral joint and, in some taxa, also via an interdigitate suture. In most loricariids the synchondral joint invariably reaches the posterior margin of the metapterygoid (Fig. 5a) while in P. nasuta and P. scutula the synchondral joint is shorter and never reaches the metapterygoid. In these species there is a bony process from the hyomandibula that articulates with the quadrate dorsally, preventing the cartilage to contact the metapterygoid (Fig. 5b; condition also shared with Neoplecostomus paranensis). (4) Contrary to most other loricariids, where the ventral process of the complex centrum falls short or extend to the mesial tip of the rib in the sixth centrum (Fig. 6a), P. nasuta and P. scutula share a longer ventral process, which reaches beyond the mesial tip of the rib in the sixth centrum (Fig. 6b; also shared with Isbrueckerichthys).

Comparative material examined. All from Brazil (in addition to that listed in Pereira & Reis, 2002): Pareiorhaphis cameroni: MCP 17276, 1 c&s, 83.8 mm SL, Santa Catarina, Água Mornas, rioTeresópolis, tributary to rio Cubatão at Águas Mornas. Pareiorhaphis nasuta: MCP 41476, 78.6 mm SL, holotype, Minas Gerais, Abre Campo, District of Granada, rio Doce drainage, ribeirão Areia Branca, tributary to the rio Matipó. MCP 37176, 10 + 2 c&s, 25.1-78.6 mm SL, paratypes, collected with the holotype. Pareiorhaphis parmula: MCP 35826, 93.3 mm SL, holotype, Paraná, Lapa, rio dos Patos, tributary to rio da Várzea on road PR-427 from Lapa to Campo Tenente. MCP 35827, 59 + 2 c&s, 45.0-94.5 mm SL (29, 45.7-94.5 mm SL), collected with the holotype. Isbrueckerichthys epakmos: MZUSP 79804, 103.1 mm SL, holotype, São Paulo, Tapiraí, Ribeira de Iguape drainage, rio Verde at Piúva, on road to Rio Verde. MCP 28276, 63, 39.5-83.3 mm SL, (20, 56.4-83.3 mm SL), paratypes, São Paulo, Tapiraí, rio Coruja, tributary to rio Juquiá, on road from Tapiraí to Juquiá near Cachoeira do Chá. Isbrueckerichthys saxicola: MCP 40209, 2, 59.7-84.7 mm SL, paratypes, Paraná, Londrina, rio Tibagi drainage, ribeirão Jacutinga. Isbrueckerichthys calvus: MCP 40208, 2, 72.5-86.2 mm SL, paratypes, Paraná, Apucarana, rio Tibagi drainage, córrego Juruba. Neoplecostomus microps: MCP 20069, 4, 47.1-89.3 mm SL, São Paulo, Piquete, ribeirão Benfica at Benfica, ca. 1 km of Piquete. MCP 20071, 13, 45.1-98.3 mm SL, São Paulo, Silveiras, ribeirão Macacos at Bairro dos Macacos. Pareiorhina carrancas: LIRP 2280, 1 + 1 c&s, 35.8-36.9 mm SL, paratypes, Minas Gerais, Carrancas, córrego Debaixo da Serra. Pareiorhina rudolphi: MCP 18052, 23 + 1 c&s, 30.4-49.3 mm SL, São Paulo, Piquete, creek tributary of rio Piquete at Benfica. Kronichthys subteres: MCP 20150, 32, 38.1-76.8 mm SL, São Paulo, Iporanga, córrego Areias, ca. 1 km SE from Bairro da Serra. Hemipsilichthys nimius: MCP 33049, 105.1 mm SL, holotype, Rio de Janeiro, Parati, rio Carrasquinho below Cachoeira do Tobogã. MCP 31990, 11, 45.7 98.1 mm SL, paratypes, collected with the holotype. Delturus brevis: MCP 26927, 2 + 1 c&s, 86.5-146.7 mm SL, paratypes, Minas Gerais, Rubelita, rio Salinas, tributary of rio Jequitinhonha near Rubelita.

Acknowledgements

We are especially grateful to Ivanildo A. Figueiredo (in memoriam) for the enthusiastic dedication to fieldwork. Specimens were collected under permits from the Instituto Estadual de Florestas (IEF-MG) issued to FV and from IBAMA, issued to RER. We thank the Ecodinâmica Consultores Associados Ltda and the Consórcio da Usina Hidrelétrica Guilman-Amorim (ArcelorMittal & Samarco Mineração SA) for the opportunity to collect fishes in the region. Additional fieldwork associated with this research was supported in part by the All Catfish Species Inventory (NSF DEB-0315963). EHLP is partially financed by a doctoral fellowship from CAPES and RER from CNPq (process # 303362/ 2007-3).

Literature Cited

Accepted December 8, 2009

Published March 31, 2010

• Ferraris, C. J., Jr. 2007. Checklist of catfishes, recent and fossil (Osteichthyes: Siluriformes), and catalogue of siluriform primary types. Zootaxa, 1418: 1-628.
• Pereira, E. H. L. 2005. Resurrection of Pareiorhaphis Miranda Ribeiro, 1918 (Teleostei: Siluriformes: Loricariidae), and description of a new species from the rio Iguaçu basin, Brazil. Neotropical Ichthyology, 3(2): 271-276.
• Pereira, E. H. L. 2009. Relações filogenéticas de Neoplecostominae Regan, 1904 (Siluriformes: Loricariidae). Unpublished PhD Dissertation, Pontifícia Universidade Católica do Rio Grande do Sul, Porto Alegre.
• Pereira, E. H. L. & R. E. Reis. 2002. Revision of the loricariid genera Hemipsilichthys and Isbrueckerichthys (Teleostei: Siluriformes), with descriptions of five new species of Hemipsilichthys Ichthyological Exploration of Freshwaters, 13(2): 97-146.
• Pereira, E. H. L., F. Vieira & R. E. Reis. 2007. A new species of sexually dimorphic Pareiorhaphis Miranda Ribeiro, 1918 (Siluriformes: Loricariidae) from the rio Doce basin, Brazil. Neotropical Ichthyology, 5(4): 443-448.
• Schaefer, S. A. 1997. The neotropical cascudinhos: systematics and biogeography of the Otocinclus catfishes (Siluriformes: Loricariidae). Proceedings of the Academy of Natural Sciences of Philadelphia, 148: 1-120.
• Taylor, W. R. & G. C. van Dyke. 1985. Revised procedures for staining and clearing small fishes and other vertebrates for bone and cartilage study. Cybium, 9: 107-119.

Publication Dates

• Publication in this collection
  19 Apr 2010
• Date of issue
  Mar 2010

History

• Received
  08 Dec 2009
• Accepted
  31 Mar 2010