Parotocinclus spilurus ( Fowler, 1941 )

Ramos, Telton Pedro A., A, Pablo Lehmann, Barros-Neto, Luciano F. & Lima, Sergio M. Q., 2016, Redescription of the endangered hypoptopomatine catfish Parotocinclus spilurus (Fowler, 1941) (Siluriformes: Loricariidae) from the upper rio Jaguaribe basin, northeastern Brazil, Neotropical Ichthyology 14 (1), No. e 150098, pp. 1-12 : 2-9

Parotocinclus spilurus ( Fowler, 1941)

Figs. 1-7 , Tables 1-2

Plecostomus spilurus Fowler, 1941: 148-150 , figs. 47-49. Type locality: Rio Salgade , Icó , Ceara (rio Salgado, Icó, Ceará, Brazil), holotype ANSP 69403 .

Parotocinclus spilurus: Garavello, 1977: 8-9 , figs. 17-18 [redescription]; Isbrücker, 1980: 81 [checklist]; Böhlke, 1984: 127 [checklist]; Burgess, 1989: 438 [checklist]; Lacerda & Evers, 1996: 88 [illustration]; Isbrücker, 2001: 31 [literature compilation]; Britski & Garavello, 2002: 286 [literature compilation]; Isbrücker, 2002: 25 [literature compilation]; Reis et al., 2003: 327 [checklist]; Rosa et al., 2003 [checklist]; Gauger & Buckup, 2005: 516 [literature compilation]; Ferraris, Jr., 2007: 283 [checklist]; Reis & Carvalho, 2007: 86 [checklist]; Lehmann & Reis, 2012: 62 [comparative material]; Ramos et al., 2013: 788 [comparative material]; Brasil, 2014: 127 [conservation status].

Diagnosis. Parotocinclus spilurus differs from all its congeners, except Parotocinclus bidentatus , P. habolthi , P. muriaensis and P. seridoensis by having the adipose fin rudimentary (a vestigial ridge composed by two small unpaired plates) or absent. Parotocinclus spilurus differs from P. bidentatus , P. habolthi and P. muriaensis by having numerous small bright spots, scattered on body and head (vs. body without spots); the pectoral girdle covered by skin medially and exposed only laterally supporting odontodes (vs. pectoral girdle completely exposed), and by the absence of accessory teeth on the premaxilla and dentary of juvenile and adults stages (vs. presence of accessory dentition). Parotocinclus spilurus also differs from P. seridoensis and other species of northeastern Brazil ( P. cearensis , P. cesarpintoi and P. spilosoma ), except P. haroldoi , by having the abdomen mostly covered by rounded dermal plates arranged in T-shape between the pectoral girdle and the anus (vs. abdomen almost naked, with a single row of elongate reduced plates on each side and a group of small rounded plates irregularly distributed in the preanal region); and by the absence of the small area of naked skin on the snout tip without odontodes (vs. snout tip completely covered by odontodes). It also differs from P. haroldoi by presence of pectoral girdle medially covered by skin and laterally exposed, supporting odontodes only laterally (vs. pectoral girdle completely exposed). Finally, P. spilurus differs from all species of Parotocinclus that inhabit the Amazon, Orinoco, and Guianas coastal basins by the canal plate of the cheek not elongated posteriorly and not contacting the pectoral girdle (vs. the canal plate elongated posteriorly on the ventral surface of head and contacting the cleithrum).

Description. Morphometric and meristic data of holotype and topotypes presented in Tables 1-2, respectively (largest examined specimen 46.1 mm SL). Body moderately short and slightly depressed. Greatest body width at cleithrum, progressively tapering to end of caudal peduncle. Dorsal profile slightly convex from snout to dorsal fin origin; straight at dorsal-fin base; approximately straight from dorsal-fin origin to rudimentary adipose fin; slightly concave from this point to base of uppermost caudal-fin rays. Greatest body depth at dorsal-fin origin. Ventral profile of head straight or slightly concave; ventral profile of trunk somewhat straight or convex from pectoral girdle to anus; somewhat concave at anus region, straight between the anus and anterior margin of the anal-fin and slightly concave at anal-fin base and straight from anal-fin end to lowermost caudal-fin rays. Head depressed and round in dorsal view; two depressions on snout in front of each nostril separated by median keel; inferior rostral margin of snout with posteriorly directed odontodes, similar in size to those on dorsal portion of snout. Odontodes on upper portion of head arranged in indistinct rows. Eyes small, positioned midway between snout tip and posterior margin of parieto-supraoccipital; distance between margin of orbit and ventral surface of head greater than orbital diameter. Dorsal iris operculum present. Interorbital space slightly convex. Mouth small; oral disk approximately round, papillose; maxillary barbels slightly smaller than orbital diameter. All teeth slender and bifid. Accessory patch of uniscupid teeth absent in dentary and premaxilla in juvenile and adults. Trunk depressed on insertion of dorsal and anal fins; caudal peduncle rounded in cross section. Pectoral girdle exposed only laterally, covered by odontodes; median region covered by skin ( Fig. 5 ); arrector fossae of pectoral girdle ellipsoid, small, extending laterally, almost meeting in at midline ( Fig. 6 ).

Dorsal fin i,7; its origin in vertical line to pelvic-fin origin; when adpressed, extending to vertical through beyond anal-fin base. Dorsal-fin first unbranched ray flexible, followed by seven branched rays. Dorsal-fin spinelet present, trapezoid-shaped, wider than base of dorsal-fin unbranched ray. Dorsal-fin locking mechanism non-functional. Nuchal plate exposed, not covered by skin. Adipose fin rudimentary or vestigial. Pectoral fin i,6; pectoral-fin unbranched ray reaching nearly half length of unbranched pelvic-fin ray. Pelvic fin i,5; unbranched ray curved, covered with small odontodes; pelvic fin reaching beyond anus, ending in anal-fin origin. Anal-fin i,5; anal-fin base flanked by three plates. Caudal fin slightly notched, emarginated, with lower lobe slightly pointed and longer than the upper lobe; principal caudal-fin rays i,14,i. Lateral-line canal in median series complete, pore tube visible from parieto-supraoccipital to caudal peduncle. Body covered by dermal plates, except region between pectoral girdle and lower lip, central area of the pectoral girdle (medial area naked and exposed only laterally supporting odontodes), and areas around bases of paired fins and anus. Abdomen mostly covered by rounded dermal plates arranged in T-shape between pectoral girdle and anus ( Fig. 5 ). Total vertebrae 26 (2 c&s).

Coloration. Background color in ethanol dark brown to yellowish brown. Specimens larger than 30 mm SL with yellowish gold rounded spots on dorsal and lateral portions of head and trunk, with lighter spot on pineal region. The spots are smaller in the anterior region of the body forming several series (5-7 series) longitudinal, and increase in size towards the caudal peduncle, converging to two or three series on lateral of trunk. Four inconspicuous dark bars on dorsum; upon pineal region features grayish yellow spot approximately on parieto-supraoccipital; ventral area of head and abdomen whitish yellow, with small sparse chromatophores on anterior portion of mouth, abdomen, pectoral fins and pre-anal region. Dorsal and caudal-fin rays with concentrated patch of dark chromatophores, forming irregular set of bands that alternates between dark brown and brownish yellow: four on dorsal fin and three to four on caudal fin, with chromatophores concentrated in conspicuous a spot on each caudal-fin lobe, especially in smaller individuals ( Fig. 2 ). Pectoral, pelvic and anal fins with same color pattern, but slightly lighter. Live coloration with same pattern described above, with spotted pattern more evident ( Fig. 4 ).

Sexual dimorphism. Males possess urogenital papilla positioned just behind anal opening and with developed dermal flap along posterodorsal margin of thickened first pelvic-fin ray. Adult males (> 30 mm SL) have the odontodes of caudal peduncle dorsally or posterodorsally directed, and modified into cluster ( Fig. 7 ), females lack this odontodes arrangement.

Distribution. Parotocinclus spilurus is known from four localities in the rio Jaguaribe basin, in the Ceará State ( Fig. 8 ). Individuals of P. spilurus were collected in the putative type locality of the species, in the rio Salgado, at Icó Municipality ( Fig. 9 ), and were also found in three other sites: the rio Lima Campos in the Lima Campos Municipality, the riacho Machado in the Lavras da Mangabeira Municipality, all from rio Salgado sub-drainage; and the rio Jaguaribe itself in the Saboeiro Municipality, suggesting a restricted geographic distribution in the upper rio Jaguaribe basin. At Icó, the sampling site was under the BR 404 bridge at rio Salgado immediately upstream the urban area. Due to the ease of access, low environmental degradation and reduced metropolitan area this site may represent the type locality of P. spilurus .

Ecological notes. In the semi-arid Caatinga region, through which the rio Jaguaribe basin flows, the rivers may completely dry in some stretches and become restricted to small ponds, especially in periods of drought, due to the irregular rainfall regime (Rosa et al., 2003). Parotocinclus spilurus was usually found in moderate current flow in clear-water streams with small rocky bottoms and gravel substrates ( Fig. 9 ). However, in recent collections P. spilurus was only found on rocky stretches below artificial dams that were releasing water, suggesting that the species may now be restricted to places where water availability is regulated by human action. The following species were also collected sympatrically in the rio Salgado: Astyanax aff. fasciatus (Cuvier) , Cichla sp. , Cichlasoma orientale Kullander , Crenicichla menezesi Ploeg , Hemigrammus marginatus Ellis , Cheirodon jaguaribensis Fowler , Hoplias malabaricus (Bloch) , Hypostomus jaguribensis (Fowler) , Hypostomus sp. , Leporinus taeniatus Lütken , Loricariichthys derbyi Fowler , Moenkhausia costae (Steindachner) , Moenkhausia sp. , Oreochromis niloticus (Linnaeus) , Pimelodella dorseyi Fowler , Pseudancistrus genisetiger Fowler , Serrapinnus heterodon (Eigenmann) , S. piaba (Lütken) , Serrasalmus brandtii Lütken and Tetragonopterus chalceus Spix & Agassiz. In addition to these species, in the rio Lima Campos were also collected: Characidium bimaculatum Fowler , Geophagus brasiliensis (Quoy & Gaimard) , Leporinus piau Fowler , and Poecilia vivipara Bloch & Schneider. In the rio Jaguaribe we also found: Pimelodella witmeri Fowler and Triportheus signatus (Garman) . At least two species, Cichla sp. and O. niloticus , are exotic in northeastern Brazil (Leão et al., 2011).

Remarks. Parotocinclus spilurus is endemic to the upper portion of the rio Jaguaribe basin in the State of Ceará. This basin is situated almost entirely within the boundaries of Ceará State, with a small portion extending to the south, into Pernambuco State, occupying part of Exú, Moreilândia and Serrita municipalities. In the last five years, several expeditions were carried out in the rio Jaguaribe basin, including one directed at capturing P. spilurus . As the result of over 40 sampling sites throughout the rio Jaguaribe basin, P. spilurus was only collected in four localities in a specific biotope of a restricted area in the upper portion of the drainage (about 16 km 2 in area of occupancy), suggesting that this species has a narrow distribution, further lending support to the belief that this area contains several restricted-range species (Nogueira et al., 2010).

Conservation status. According to IUCN criteria (International Union for Conservation of Naturae (IUCN), 2001, 2010) P. spilurus was categorized as endangered (EN) in the recently published Brazil’s official list of endangered species of fish and aquatic invertebrates ( Brasil, 2014), representing one of the first freshwater fish species of the Mid-Northeastern Caatinga ecoregions to be recognized as imperiled. The region deserves more attention when considering that the rio Jaguaribe is one of the basins that will receive waters from the rio São Francisco transposition.

Material Examined. All from Brazil. Ceará State. rio Jaguaribe basin. ANSP 69403 , 28.6 mm SL, holotype; ANSP 69404 , 5 , 24.4- 28.4 mm SL (1 c&s), paratypes, rio Salgado , Icó Municipality , 1937, R. von Ihering; UFRN 0321, 10, 12.2-41.9 mm SL (1 c&s); UFRN 0376, 2, 33.9-35.9 mm SL; MCP 48176, 4 , 30.8-38.4 mm SL; UFRN 0389, 4, 39.2-46.1 mm SL; UFRN 1248, 1, 34.8 mm SL, 11 Jul 2012, S. Lima, L. Neto, W. Berbel, R. Paiva, C. Alencar & F. Freire; UFRN 1248, 1, 34.8 mm SL; UFRN 1253, 1, 33.3 mm SL, 22 Mar 2013, Lima Campos Municipality , rio Lima Campos , 6°24’13.7”S 38°57’19.4”W, S. Lima, T. Ramos, W. Berbel, L. Neto, S. Moraes & A. Moraes; UFRN 0345, 1, 33.1 mm SL, Saboeiro Municipality, 6°32’31.1”S 39°54’32.5”W, 10 Jun 2012, S. Lima, L. Neto, W. Berbel, R. Paiva, C. Alencar & F. Freire; UFRN 1252, 4, 31.5-35.9 mm SL; UFRN 1255, 4, 32-37.2 mm SL; UFRN 1300, 1, 40.2 mm SL, Icó Municipality, rio Salgado , 6°24’53.8’’S 38°52’23’’W, 21 Mar 2013, S. Lima, T. Ramos, W. Berbel, L. Neto, S. Moraes & A. Moraes; UFPB 9012 , 9 , 17.7- 31.3 mm SL, Icó Municipality, rio Salgado , rio Jaguaribe basin, 6°24’28.9”S 38°52’06.6”W, 12 Jun 2011, T. Ramos, S. Ramos, R. Ramos & C. Zawadzki; UFPB 9013 , 3 , 28.5-39.4 mm SL, Lavras da Mangabeira Municipality , Machado small stream tributary to rio Salgado , rio Jaguaribe basin, 6°42’25.7’’S 39°01’40.4’’W, 19 Jul 2009, T. Ramos, P. Honório & G. Moro; UFPB 9989 , 17 , 21.6-26.9 mm SL (2 c&s), Senador Pompeu Municipality, riacho Caconde, Senador Pompeu, 5°33’44.2”S 39°21’11.4”W, 22 Jul 2009, T. Ramos, P. Honório & G. Moro .

Figures

Fig. 1. Lateral, dorsal, and ventral views of Parotocinclus spilurus, holotype ANSP 69403, 28.6 mm SL female; Brazil, Ceará State, Icó Municipality, rio Salgado, rio Jaguaribe basin.

Fig. 2. Lateral, dorsal, and ventral views of Parotocinclus spilurus, topotype UFRN 1255, 37.2 mm SL, female; Brazil, Ceará State, Icó Municipality, rio Salgado, rio Jaguaribe basin.

Fig. 3. Ontogenetic variation in Parotocinclus spilurus topotypes, UFRN 0321, 0389, UFPB 9989, specimens A to C between 46.5-30.5 mm SL, D to G between 26.9-21.6 mm SL. Specimens represented in scale.

Fig. 4. Parotocinclus spilurus, live (UFRN 1255, 37.2 mm SL) specimen just after collection from rio Salgado (type locality), Icó, Ceará.

Fig. 5. Ventral view of abdominal region showing the lateral plates and preanal platelets arranged in T-shape in Parotocinclus spilurus. Abbreviations: LAPS, lateral abdominal plates series; MAPS, median abdominal plate series; PAR, pre-anal region.

Fig. 6. Ventral view of pectoral girdle of Parotocinclus spilurus, UFRN 0321, 34.9 mm SL, female. Abbreviations: AFO, arrector fossa opening; CL, cleithrum; CO, coracoid.

Fig. 7. Dermal plates at posterior end of caudal peduncle of Parotocinclusspilurus,topotype, UFRN1300,male, 40.2 mm SL. Arrow indicates odontodes dorsally or posterodorsally directed and modified into a cluster. Scale bar = 1 mm.

Fig. 8. Geographic distribution of Parotoncinclus spilurus in upper Jaguaribe, Ceará State, northeastern Brazil. Open symbol represents type locality Icó Municipality, rio Salgado, rio Jaguaribe basin.

Fig. 9. The putative type locality of Parotocinclus spilurus, Brazil, Ceará, Icó, rio Salgado, rio Jaguaribe basin.