Pareiorhaphis parmula, Lopes Pereira, 2005

Lopes Pereira, Edson H., 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), pp. 271-276 : 272-275

Pareiorhaphis parmula , new species

Fig. 1

Holotype. MCP 35826, male, 93.3 mm SL; Brazil: Paraná: Lapa: rio Iguaçu basin: rio dos Patos, tributary to rio da Várzea, on road PR-427 from Lapa to Campo do Tenente , 25º50’36.8"S 049º43’39.2"W, 29 Oct 2004, E. H. L. Pereira, L. F. Duboc, V. Abilhôa, and R. Torres . Paratypes. Brazil: Paraná: MCP 35827, 59 + 2 c&s (29) 45.7-94.5 mm SL and MHNCI 10883 , 3 (1) 59.6- 73.6 mm SL; all collected with the holotype . MCP 35556, 10 (7) 39.6-86.5 mm SL; rio dos Patos, tributary to rio da Várzea, Lapa, 25º50’38"S 049º43’39"W, 3 Jul 2004 , V. Abilhôa & L. F. Duboc .

Diagnosis. Pareiorhaphis parmula can be distinguished from all other Pareiorhaphis species by having one small plate on each side of the pectoral girdle, just posterior to the gill opening (vs. abdomen totally naked in all other species). The clubshaped pectoral-fin spine, broadening from base to apex on adult males, also distinguishes P. parmula from other Pareiorhaphis species with the exception of P. vestigipinnis . From P. vestigipinnis , the new species can be distinguished by having an adipose fin.

Pareiorhaphis parmula can be further distinguished from P. vestigipinnis , P. stephane , P. nudula , and P. regani by the longer caudal peduncle (34.4-37.9 vs. 27.9-34.0 % SL); from P. eurycephalus , P. hypselurus , P. stomias , and P. splendens by the smaller cleithral width (27.9-31.0 vs. 32.1-40.0 % SL); from P. cerosa , P. bahiana , P. azygolechis , and P. mutuca by the smaller caudal peduncle depth (8.2-9.2 vs. 9.4-11.7 % SL); from P. garbei , P. calmoni , and P. hystrix by the number of dentary teeth (32-48 vs. 60-89, 49-84 and 42-57, respectively); from P. steindachneri by having the longest hypertrophied odontodes on cheeks of mature males shorter than interorbital width (vs. longer than interorbital width).

Description. Counts and proportional measurements presented in Table 1. Standard length of measured specimens 43.5 to 94.5 mm. See Fig. 1 for general body aspect. Dorsal surface of body covered by plates except for naked area around dorsal fin. Body moderately depressed. Progressively narrowing from cleithrum to end of caudal peduncle. Dorsal profile of body slightly convex, rising from snout tip to origin of dorsal fin and then descending to end of caudal peduncle. Trunk and caudal peduncle mostly ovoid in cross-section, slightly flattened ventrally and more compressed caudally. Greatest body depth at dorsal-fin origin. Least body depth at shallowest part of caudal peduncle. Ventral surface of head, region from pelvic-fin insertion to anal-fin origin, and region around anal fin completely naked. Abdomen almost totally naked, except for one (rarely two) small platelet on each side just posterior to gill opening. Plates difficult to see in specimens smaller than 50 mm SL.

Head broad and moderately depressed. Anterior profile of head rounded in dorsal view. Interorbital space slightly concave, nearly flattened. Three small ridges on dorsal surface of head, one median ridge from snout tip to area between nostrils, and one pair of ridges from nostril to anterior margin of orbit. Lateral margin of head covered with minute odontodes. Snout in lateral profile gently convex. Mature males with well-developed soft fleshy lobes on lateral portion of head. Soft fleshy area ornamented with short and delicate hypertrophied odontodes. Eye moderately small (12.7 to 15.9% HL), dorsolaterally placed. Iris with small dorsal flap covering pupil. Lips roundish and developed, occupying most of ventral surface of head. Lower lip almost reaching pectoral girdle and covered with minute papillae, which decrease in size towards its edge. Posterior edge slightly fringed. Maxil- lary barbell short and free distally (united to lip by membrane only basally). Anterior ends of premaxillae and dentaries slightly curved inwards. Teeth slender and bicuspid, inner cusp slightly curved inwards. Lateral cusp minute and pointed, never reaching half length of inner cusp.

Dorsal fin originating slightly posterior to vertical line passing through pelvic-fin origin; nuchal plate and dorsal-fin spinelet present but dorsal-fin locking mechanism non-functional. Dorsal fin spinelet oval. Dorsal-fin spine moderately flexible, followed by 7 branched rays. Adipose fin present, preceded by none to 3 median, unpaired pre-adipose azygous plates (usually 1-2). Pectoral fin of moderate size; with spine slightly curved, covered by minute odontodes in immature males and females. Mature males with pectoral-fin spine club-shaped, broadening from base to apex, bearing few straight and delicate hypertrophied odontodes on outer face; 6 branched rays. First and second branched rays slightly longer than spine. Subsequent branched rays decrease gradually in size. Posterior margin of pectoral fin may reach half length of pelvic fin when adpressed in mature males. Pelvicfin moderate in size, with one spine and 5 branched rays, tip not reaching insertion of anal fin when adpressed. Pelvic-fin spine depressed, covered with minute odontodes ventrally and laterally; dermal flap on its dorsal surface present, but not very large, extending to tip of spine in mature males. Anal fin with one unbranched and 5 branched rays. Caudal fin border concave; lower lobe slightly longer than upper; 14 branched rays. Procurrent caudal-fin rays 3-4 dorsal and 3 ventral.

Color in alcohol. Ground color of dorsal surface of body and head dark grey, sometimes light grey, whitish ventrally. Dorsum covered by dark blotches. Usually these blotches forming four irregular diffuse saddles located at origin of dorsal fin, behind dorsal-fin base, on adipose fin, and between adipose and caudal fins. Flanks covered by dark gray blotches, irregularly arranged and sized. Sometimes posterior half of flanks with roundish spots or indefinite mid-lateral stripe. Mature males with fleshy lobes on margin of head light gray. Spines of dorsal, pectoral, pelvic, and anal fins plain grayish or with two or three wide dark stripes. Branched rays uniformly grayish or with small, dark-brown blotches along entire length, sometimes forming two or three narrow bands. Spines and branched rays of pectoral and pelvic fins of mature males with four or five wide dark dots, sometimes forming darker irregular lines. Caudal fin with two or three narrow bands, more visible when fin widely open. Fin membranes hyaline. Ventral surface between anal-fin origin and posterior portion of lower lip pale yellow or whitish. Ventral margin of head, upper lip, and ventral portion of caudal peduncle grayish.

Distribution. Pareiorhaphis parmula is known from the rio dos Patos, headwaters of the rio Iguaçu in Paraná State, Brazil ( Fig. 2).

Ecological notes. The type locality where all specimens of Pareirhaphis parmula were collected, is a small creek flowing through a landscape of mixed open field and forest. The stretch sampled is narrow (about 2-4 m wide) and shallow (about 0.4-1.0 m deep). The stream bottom was formed of small to medium-sized rocks, loose stones and gravel. The water was clear and moderate to fast flowing. Grass or other vegetation is usually present on the margins. The fishes are usually found among the bottom rocks and stones.

Etymology. The name parmula is Latin, diminutive from parma, meaning small, light shield, in allusion to the small plate located ventrally just behind the gill opening. A noun in apposition.