Zootaxa 1372: 53–68 (2006) ISSN 1175-5326 (print edition) www.mapress.com/zootaxa/ ZOOTAXA 1372 Copyright © 2006 Magnolia Press ISSN1175-5334(online edition) Two new species of Isbrueckerichthys Derijst, 1996 (Siluriformes: Loricariidae) from the rio Paranapanema basin, Brazil FERNANDO C. JEREP1, OSCAR A. SHIBATTA1, EDSON H. L. PEREIRA2 & OSVALDO T. OYAKAWA3 1Programa de Pós-Graduação em Ciências Biológicas, Departamento de Biologia Animal e Vegetal, Centro de Ciências Biológicas, Universidade Estadual de Londrina, 86051-990, Londrina, PR. Brazil. E-mail: [email protected] 2Laboratory of Ichthyology, Pontifícia Universidade Católica do Rio Grande do Sul, P.O. Box 1429, 90619- 900, Porto Alegre, RS, Brazil. E-mail: [email protected] 3Museu de Zoologia da Universidade de São Paulo, P.O. Box 42594-970, São Paulo, SP, Brazil. E-mail: [email protected] Abstract Two new Isbrueckerichthys species from Paranapanema river basin are described, I. saxicola and I. calvus, respectively from ribeirão Jacutinga and rio Taquara affluents. Both species present all diagnostic characters of the genus, and differ from their congeners by having bicuspid teeth (vs. simple teeth in I. alipionis), hypertrophied odontodes along the lateral margin of head (vs. hypertrophied odontodes only at the anterior portion of snout in I. epakmos) and longer pectoral-fin spine and shorter caudal peduncle length in relation to I. duseni. The new species can be distinguished from each other by number of odontodes in each minute abdominal platelet (more than six in I. saxicola vs. at most six in I. calvus); by the presence of a plated area under the three first plates of the lateral line in I. saxicola vs. its absence in I. calvus in which this region is naked; by a exposed portion of cleithrum bordering the entire margin of the opercular opening in I. saxicola vs. bordering just the superior portion in I. calvus; and by presenting the exposed surface of supraoccipital plain or slightly convex in I. saxicola vs. strongly convex with an area without odontodes on the center in I. calvus. Keywords: Neotropics, Paranapanema basin, Neoplecostominae. Introduction The genus Isbrueckerichthys was proposed by Derijst (1996) to include the species Pareiorhaphis duseni (Miranda Ribeiro, 1907) and Pareiorhaphis alipionis Gosline, 1947. This proposal was justified based on the discovery of an earlier type-species designation Accepted by M. de Carvalho: 30 Oct. 2006; published: 4 Dec. 2006 53 ZOOTAXA by Regan (1920), which had fixed Hemipsilichthys calmoni Steindachner, 1907 as the type 1372 species of genus Pareiorhaphis, making Pareiorhaphis a synonym of Hemipsilichthys and dislocating P. duseni and P. alipionis, once they do not fit in the new designation (sensu Derijst 1996). Isbrueckerichthys is composed of small- to medium-sized species (up to 90.2 mm SL) of loricariids (suckermouth armored catfishes). Although a phylogenetic diagnosis for Isbrueckerichthys is until now unavailable, this genus is distinguished from other neoplecostomines by a combination of characters: small naked area behind the pterotic- supracleithrum, abdomen with small platelets embedded in skin between pectoral girdle and pelvic-fin insertions, dorsal fin with one spine and seven branched rays, caudal peduncle ovoid in cross-section and lacking a series of papillae on the lower lip of the dentaries. Species of this genus are commonly found in small to medium headwater streams with clear, fast running, and well-oxygenated water, where the bottom is composed of rocks, boulders, and sometimes gravel (Pereira & Reis 2002). The three described species of Isbrueckerichthys are recognized and thought to be endemic to the rio Ribeira de Iguape basin: Isbrueckerichthys duseni (Miranda Ribeiro, 1907) from the upper reaches of that basin in Paraná State, I. alipionis (Gosline, 1947), from the rio Betari, a tributary of rio Ribeira de Iguape and I. epakmos Pereira & Oyakawa, 2003 from a tributary of the rio Juquiá in São Paulo State. In the present paper two new species of Isbrueckerichthys are described, both of them collected in headwater streams of rio Tibagi, rio Paranapanema basin, in Paraná State, Brazil. These species represent the first Isbrueckerichthys species in the Paraná River basin and an increase in the geographic distribution range of the genus. Material and methods Specimens examined belong to the Museu de Zoologia da Universidade Estadual de Londrina, Londrina, State of Paraná (MZUEL), Museu de Zoologia da Universidade de São Paulo, State of São Paulo (MZUSP) and Museu de Ciências e Tecnologia da Pontifícia Universidade Católica do Rio Grande do Sul, Porto Alegre, State of Rio Grande do Sul (MCP). All measurements were taken point to point with digital calipers to the nearest 0.1 mm, under a dissecting microscope when necessary. Measurements and counts of bilaterally symmetrical features were taken from the left side of the body whenever possible; if a feature was missing or broken on the left side, it was examined on the right side. Measurements follow Boeseman (1968), Muller, Mazzoni and Weber (2001), Weber (1985), Bockmann and Ribeiro (2003) and Pereira and Oyakawa (2003). Counts of median plate series were taken according to Schaefer (1997). Additional counts include: plates between dorsal and adipose fins (number of plates in dorsal series between last dorsal-fin branched ray insertion and origin of adipose-fin spine) and plates between adipose and 54 © 2006 Magnolia Press JEREP ET AL. caudal fins (number of plates in dorsal series from just posterior to the adipose-fin ZOOTAXA 1372 membrane to the caudal fin). In case of missing teeth, the space left was counted as a tooth. Standard length is expressed in mm. All other measurements are expressed as percents of standard length, except subunits of the head, which are expressed as percents of head length. Key to the species of Isbrueckerichthys 1 Teeth of dentary and premaxilla without lateral cusp..................................................... ....................................................................I. alipionis (Ribeira de Iguape River basin) - Teeth of dentary and premaxilla with small lateral cusp...............................................2 2. Mature males with a clump of hypertrophied odontodes only on anterior portion of snout...........................................................I. epakmos (Ribeira de Iguape River basin) - Mature males with hypertrophied odontodes along the lateral margin of head............3 3. Short pectoral-fin spine (17.3–21.4 % SL) and long caudal peduncle length (34.6–38.2 % SL).............................................................I. duseni (Ribeira de Iguape River basin) - Long pectoral-fin spine (21.5–27.4 % SL) and short caudal peduncle length (26.4–30.0 % SL).........................................................................................................4 4. Minute abdominal platelets with much more than six odontodes; plated area under the first three plates of the lateral line; exposed portion of cleithrum bordering all the pos- terior margin of the opercular opening on lateral side of the body; exposed surface of supraoccipital plane or slightly convex...............I. saxicolasp. n. (Paraná River basin) - Minute abdominal platelets with at most six odontodes; nude area under the first three plates of the lateral line; cleithrum not exposed, or when exposed, bordering just the superior portion of posterior margin of the opercular opening on lateral side of the body; exposed surface of supraoccipital strongly convex, with an area without odon- todes at the center...................................................I. calvussp. n.(Paraná River basin) Isbrueckerichthys saxicola,new species Fig. 1. Holotype. MZUEL 3716; 87.7 mm SL; male; Brazil; Paraná State; Londrina; rio Tibagi basin; ribeirão Jacutinga; 23º14´30”S/51º13´05”W; 18 August 2005; F. C. Jerep, E. S. da Silva, A. Souza. Paratypes. (all from the same locality and collector as the holotype). MZUEL 3717; 3 (3) 59.7–84.7 mm SL; MCP 40209; 2 (2) 59.7-84.7 mm SL; collected with the holotype. MZUEL 3718; 1 (1) 77.8 mm SL; 31 March 2004; H. Mori, F. C. Jerep, E. S. da Silva, A. Souza. MZUSP 90803; 1 (1) 63.6 mm SL; 14 April 2005, F. C. Jerep, E. S. da Silva, A. Souza. TWO NEW ISBRUECKERICHTHYS © 2006 Magnolia Press 55 ZOOTAXA Diagnosis.Isbrueckerichthys saxicola can be distinguished from I. alipionis by having 1372 bifid teeth, with a small lateral cusp (vs. teeth simple, without lateral cusp). Differ from I. epakmos by mature males having margins of head with thin fleshy lobes (vs. soft and rugose fleshy area well developed on anterior portion of snout of mature males) and by the presence of short hypertrophied odontodes along the lateral margin of head (vs. presence of a clump of hypertrophied odontodes located only on anterior portion of snout, directed forward or slightly upwards). Differ from I. duseni by having longer pectoral-fin spine (23.0–27.4 vs. 17.3–21.4 % SL) and shorter caudal peduncle length (27.3–30.0 vs. 34.6–38.2 % SL). Differ from I. calvus by having minute abdominal platelets with frequently about 12 odontodes (vs. minute abdominal platelets with at most six odontodes); plated area under the first three plates of the lateral line (Fig. 3) (vs. naked area under the first three plates of the lateral line); exposed portion of cleithrum bordering the posterior margin of the opercular opening on lateral side of the body (Fig. 3) (vs. cleithrum not exposed, or when exposed, bordering just the superior portion of posterior margin of the opercular opening); and exposed surface of supraoccipital flat or slightly convex (vs. exposed surface of supraoccipital strongly convex with an area without odontodes at the center). Description. Counts and proportional measurements presented in Table 1. Dorsal surface of the 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 the body slightly convex, rising from snout tip to origin of dorsal fin and descending from this point 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 nuchal plate. Ventral surface of the head, region from pelvic-fin insertion to anal-fin origin and around the anal fin totally naked. Abdomen covered by minute platelets, most of them bearing more than 6 odontodes (frequently about 12), scattered between posterior margin of lower lip and insertion of pelvic fin. Head broad and depressed. Anterior profile of head slightly triangular to roundish in dorsal view, more rounded in mature males. Three slightly elevated ridges between orbits and snout tip, lateral ridges more prominent. Dorsal region between orbits concave; upper margin of the orbit slightly elevated; supraoccipital dorsal surface plane, sometimes slightly convex. Eye moderately small dorsolaterally placed. Iris with minute dorsal flap covering pupil. Margins of head covered by minute odontodes; mature males with thin fleshy lobes and short hypertrophied odontodes along the lateral margin of head. Lips roundish and well developed, occupying most of ventral surface of head. Lower lip reaching pectoral girdle and covered with minute papillae, which decrease in size towards its edge. Papillate surface of lower lip projecting between dentary and premaxillary rami. Maxillary barbel short, coalesced with lower lip and ornamented with small papillae. Teeth small and bicuspid, inner cusp slightly curved inwards. Lateral cusp small, not reaching half-length of inner cusp (three times shorter than inner cusp). 56 © 2006 Magnolia Press JEREP ET AL. TABLE 1. Morphometrics and meristics data for Isbrueckerichthys calvus and I. saxicola. ZOOTAXA 1372 I. calvus I. saxicola Character Holotype n = 17 X ± SD Holotype n = 6 X ± SD Standard length (mm) 87.3 42.4–90.2 87.7 59.7–87.7 Percents of standard length Head length 31.6 31.4–35.0 33.05 ± 0.95 31.6 31.6–35.0 32.56 ± 1.24 Predorsal length 41.9 40.6–43.7 42.60 ± 0.81 40.8 40.8–45.9 42.82 ± 1.77 Postdorsal length 44.5 38.2–45.9 42.35 ± 2.27 44.2 39.7–44.2 42.37 ± 1.84 Dorsal-fin spine length 20.4 19.7–24.0 21.75 ± 1.39 22.0 18.8–22.0 20.50 ± 1.25 Anal-fin spine length 18.1 14.8–19.5 17.27 ± 1.22 18.1 14.6–18.1 15.66 ± 1.30 Pectoral-fin spine length 24.2 21.5–26.4 24.13 ± 1.53 27.4 23.0–27.4 24.47 ± 1.60 Pelvic-fin spine length 19.5 18.6–22.8 20.44 ± 1.17 22.5 19.6–22.5 20.94 ± 0.99 Adipose-fin spine length 8.7 7.3–10.6 9.01 ± 0.78 7.5 5.9–7.5 6.51 ± 0.60 Upper caudal-fin ray 19.6 17.2–27.9 21.69 ± 3.28 24.0 20.8–24.0 22.37 ± 1.26 Lower caudal-fin ray 20.5 18.6–29.6 24.21 ± 3.27 24.4 21.7–26.6 24.64 ± 1.93 Trunk length 16.9 15.9–19.4 17.55 ± 1.04 16.6 16.6–18.5 17.36 ± 0.72 Abdominal length 26.5 24.2–28.9 26.36 ± 1.28 25.2 25.1–26.2 25.54 ± 0.49 Cleithral width 30.3 29.0–31.5 29.95 ± 0.62 28.9 28.9–30.9 29.78 ± 0.74 Body depth at dorsal origin 19.3 18.8–22.2 20.79 ± 1.16 20.5 17.7–20.5 18.92 ± 0.98 Body width at dorsal origin 24.6 20.9–26.9 24.21 ± 1.46 23.2 21.7–24.2 23.18 ± 0.83 Body width at anal origin 16.8 13.2–16.8 15.20 ± 0.89 14.7 12.0–14.7 13.15 ± 0.86 Caudal peduncle length 27.9 26.4–29.7 28.24 ± 1.03 29.1 27.3–30.0 28.77 ± 0.93 Caudal peduncle depth 10.1 8.6–10.3 9.46 ± 0.40 8.7 8.3–8.9 8.65 ± 0.25 Caudal peduncle width 9.3 5.3–9.3 7.24 ± 0.95 6.7 5.6–6.8 6.44 ± 0.48 Percents of head length Snout length 67.2 60.5–67.5 64.10 ± 1.91 66.2 63.6–66.2 64.80 ± 1.00 Orbital diameter 11.7 11.2–14.5 12.41 ± 0.88 12.0 10.8–12.6 11.86 ± 0.59 Least interorbital width 32.8 27.5–36.4 31.11 ± 2.59 32.2 29.7–32.2 31.22 ± 0.84 Least internostril width 10.6 9.9–12.1 10.84 ± 0.51 10.0 9.5–11.3 10.33 ± 0.65 Eye-nostril distance 15.0 12.6–15.5 14.02 ± 0.89 13.1 12.5–15.0 13.48 ± 0.90 Head depth 61.8 53.4–62.9 58.31 ± 3.01 63.0 54.1–63.0 58.40 ± 3.25 Oral disk width 58.3 52.0–65.9 59.65 ± 3.37 66.6 54.2–68.6 61.57 ± 5.94 Mandibular ramus 21.0 17.2–23.3 20.34 ± 1.83 17.6 17.6–21.7 19.83 ± 1.65 Counts Median plates series 27 27–29 27.9 ± 0.66 30 29–30 29.67 ± 0.52 Dorsal plates below dorsal-fin 6 6–7 6.59 ± 0.51 8 7–8 7.50 ± 0.55 base Dorsal median unpaired plates 1 1–2 1.41 ± 0.51 2 1–2 1.67 ± 0.52 Plates between dorsal/adipose 8 7–9 7.82 ± 0.73 8 8–10 8.50 ± 0.84 TWO NEW ISBRUECKERICHTHYS © 2006 Magnolia Press 57 ZOOTAXA TABLE 1 (continued). 1372 I. calvus I. saxicola Character Holotype n = 17 X ± SD Holotype n = 6 X ± SD Plates between adipose/caudal 7 7–8 7.59 ± 0.51 7 7–8 7.50 ± 0.55 Ventral plates above anal-fin 4 3–4 3.82 ± 0.39 4 3–4 3.33 ± 0.52 base Ventral plates between end of 12 11–14 12.24 ± 0.75 14 14–15 14.33 ± 0.52 anal-fin base and caudal-fin Dorsal-fin branched rays 6 6–7 6.90 ± 0.24 7 6–7 6.50 ± 0.55 Pectoral-fin branched rays 6 6–6 6.00 ± 0 6 6–6 6.00 ± 0 Pelvic-fin branched rays 5 5–5 5.00 ± 0 5 5–5 5.00 ± 0 Anal-fin branched rays 5 5–5 5.00 ± 0 5 5–5 5.00 ± 0 Caudal-fin rays 14 14–14 14.00 ± 0 14 14–14 14.00 ± 0 Premaxillary teeth 33 28–43 34.41 ± 4.61 37 36–42 38.50 ± 2.17 Dentary teeth 29 27–46 33.76 ± 5.34 33 33–41 36.17 ± 2.86 Cleithrum partially exposed, extending from pectoral-fin insertion to ventral margin of pterotic-supracleithrum, bordering the posterior margin of opercular opening on lateral side of body. Exposed portion of the cleithrum tight ventrally becoming broad on its dorsal extremity. Region below three initial plates of lateral line (just posterior to pterotic- supracleithrum) plated with three to five small platelets. Dorsal fin originating on vertical line passing through pelvic-fin origin, and finishing on vertical line passing through anal-fin origin; nuchal plate present; dorsal-fin spinelet absent, although some specimens have it, locking mechanism non-functional (Fig. 3). Dorsal-fin spine moderately flexible. Adipose fin present, preceded by one to two median, unpaired pre-adipose azygous plates. Pectoral fin moderate in size; with curved and depressed spine, which have a short extension of skin on its tip; spine covered with short hypertrophied odontodes, mainly on its lateral and ventral surface; dorsal surface with discrete dermal flap along its entire length. First and second branched rays as long as the spine. Subsequent branched rays reduced gradually in size, last ray less than half length of first one. Posterior margin of pectoral fin straight, overlapping approximately half-length of pelvic fin when adpressed. Pelvic fin moderate in size, 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, extending to spine tip. Anal fin with the first ray unbranched. Distal profile of caudal fin concave, lower lobe slightly longer than upper. One peculiar feature was observed in two specimens of I. saxicola. They have the dorsal-fin spinelet reduced to a rectangular platelike structure, just like mentioned by Armbruster (2004) as present in most neoplecostomines. It is the first time that this structure is observed into the genus (Pereira & Reis 2002; Pereira & Oyakawa 2003; Armbruster 2004; Pereira 2005). 58 © 2006 Magnolia Press JEREP ET AL. ZOOTAXA 1372 FIGURE 1. Isbrueckerichthys saxicola, holotype, MZUEL 3716, male, 87.7 mm SL. Brazil: State of Paraná: Londrina: rio Tibagi basin, ribeirão Jacutinga. Color in alcohol. Ground color of upper surface of head and body brown or grayish brown; pale yellow ventrally. Dorsum and flanks mostly plain but sometimes with dark brown blotches of various sizes and shapes, associated with lighter blotches irregularly arranged. Dorsal light blotches sometimes arranged to form four inconspicuous saddles on dorsum at dorsal-fin origin, at posterior portion of dorsal-fin base, between end of dorsal fin and adipose fin, and between adipose and caudal fins. Lighter vertical thin blotch on the lateral side in the end of caudal peduncle, sometimes not continuous. Ventral margin of head and outer portion of upper lip homogeneously light brownish; ventral portion of TWO NEW ISBRUECKERICHTHYS © 2006 Magnolia Press 59 ZOOTAXA caudal peduncle dusky, sometimes with small brown blotches. Ventral surface 1372 unpigmented between head and anal-fin origin. Spines of dorsal, pectoral, pelvic, anal and caudal fins grayish brown with four to six dark spots; branched fin rays with two to three spots, forming transverse stripes; interradial membrane of fins hyaline. Distribution. This species is only known from the headwater of ribeirão Jacutinga, in low rio Tibagi basin, Paraná State, Brazil (Fig. 4). Etymology. The species name saxicola, a Latin adjective, means living among the rocks, in allusion to the habitat where they are found (under the rocks in the bottom of the rivers). Ecological notes. The type locality where all specimens of Isbrueckerichthys saxicola were collected is a small creek located near the urban area of Londrina city, flowing through a landscape of mixed open fields and riparian vegetation, sometimes with a very degraded margin. Grass or other vegetation is usually present on the margins. The stretch sampled is narrow (about two to four meter wide) and shallow (about 0.2–1.0 m deep). The stream bottom was rocky, with small to medium-sized rocks, loose stones and gravel; sometimes with sand and mud on the small pools bottom. The water was clear to turbid and moderate to strong flowing. The fishes are usually found on the bottom among rocks and stones. The discovery of I. saxicola was unusual considering the fact that the type locality (ribeirão Jacutinga) is an urban and degraded stream. The only six specimens of this species was collected in a not polluted short parcel (about 50 m, with rock bottom and fast flow) of the stream´s headwater, them were not found on the rest of the stream or on neighbors streams. It appears that both new species are not tolerant to polluted or not oxygenated waters, just like theirs congeners (Oyakawa et al. 2006). The following species occur syntopically with Isbrueckerichthys saxicola:Apareiodon ibitiensis (Steindachner); Astyanax altiparanae Garutti & Britski; Astyanax eigenmanniorum (Cope); Bryconamericus iheringii (Boulenger); Characidium gomesi Travassos; Hisonotus depressicauda (Miranda Ribeiro); Hypostomus ancistroides (Ihering), Hypostomus nigromaculatus (Schubart), Hypostomus regani (Ihering), Imparfinis schubarti (Gomes); Oreochromis niloticus (Hasselquist), Poecilia reticulata Petersand Rhamdia quelen (Quoy & Gaimard). Isbrueckerichthys calvus, new species Fig. 2. Holotype. MZUEL 3714; 87.3 mm SL; male; Brazil; Paraná State; Apucarana; rio Tibagi basin; córrego Juruba; 23º34’44.6”S/51º22’12.6”W; 08 September 2005; F. C. Jerep, E. S. da Silva, A. Souza. Paratypes. MZUEL 3724; 9 (6) 65.5–90.2 mm SL; MCP 40208; 2 (2) 72.55-86.24 mm SL; collected with the holotype. MCP 40207; 2 (2) 46.36-67.08 mm SL; Califórnia; rio Tibagi basin; ribeirão Água dos Oito; 21 October 2004; F.C. Jerep, E.S. da Silva, A. 60 © 2006 Magnolia Press JEREP ET AL. Souza. MZUSP 90804; 3 (3) 63.0–73.5 mm SL; Apucarana; rio Tibagi basin; córrego ZOOTAXA 1372 Juruba; 23º33’58.2”S/51º24’17.4”W; 08 September 2005; F.C. Jerep, E.S. da Silva, A. Souza. MZUEL 3638; 5 (4) 42.4–78.8 mm SL; Califórnia; rio Tibagi basin; ribeirão Água dos Oito; 21 October 2004; F. C. Jerep, E. S. da Silva, A. Souza. MZUEL 3715; 1 (1) 65.6 mm SL; Califórnia; rio Tibagi basin; ribeirão Água dos Oito; 19 Oct 2000; A. Souza. Diagnosis. Isbrueckerichthys calvus can be distinguished from I. alipionis by having bifid teeth, with a small lateral cusp (vs. teeth without lateral cusp). Differ from I. epakmos, by mature males having margins of the head with thin fleshy lobes (vs. soft and rugose fleshy area well developed on anterior portion of snout of mature males) and by the presence of short hypertrophied odontodes along the lateral margin of head (vs. presence of a clump of hypertrophied odontodes located only on anterior portion of snout, directed forward or slightly upwards). Differ from I. duseni by having a longer pectoral-fin spine (21.5–26.4 % vs. 17.3–21.4 % SL) and a shorter caudal peduncle length (26.4–29.7 % vs. 34.6–38.2 % SL). Differ from I. saxicola by having minute abdominal platelets with at most six odontodes (vs. minute abdominal platelets with much more than six odontodes, frequently 12); nude area under the first three plates of the lateral line (Fig. 3) (vs. plated area under the first three plates of the lateral line); cleithrum not exposed, or when exposed, bordering just the superior portion of posterior margin of the opercular opening on lateral side of the body (Fig. 3) (exposed portion of cleithrum bordering all the posterior margin of the opercular opening); exposed surface of supraoccipital strongly convex, with an area without odontodes on the center (vs. exposed surface of supraoccipital plane or slightly convex). Description. Counts and proportional measurements presented in Table 1. Dorsal surface of the 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 the 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. Ventral surface of the head, region from pelvic-fin insertion to anal fin origin and around the anal fin totally naked. Abdomen covered by minute platelets, bearing at most six odontodes (frequently about three), scattered between posterior margin of lower lip and insertion of pelvic fin; sometimes concentrated in central area of abdomen. Head broad and depressed. Anterior profile of head slightly triangular to roundish in dorsal view, more rounded in mature males. Three slightly elevated ridges between orbits and snout tip, lateral ridges more prominent. Dorsal region between orbits concave; upper margin of the orbit slightly elevated; supraoccipital dorsal surface strongly convex, with an area without odontodes at the center. Eye moderately small dorsolaterally placed. Iris with minute dorsal flap covering pupil. Margins of head covered by minute odontodes; mature males with thin flesh lobes and short hypertrophied odontodes along the lateral margin of head. Lips roundish and well developed, occupying most of ventral surface of TWO NEW ISBRUECKERICHTHYS © 2006 Magnolia Press 61 ZOOTAXA head. Lower lip reaching pectoral girdle and covered by minute papillae, which decrease 1372 in size towards its edge. Papillate surface of lower lip projecting between dentary and premaxillary rami. Maxillary barbel short, coalesced with lower lip and ornamented with small papillae. Teeth small and bicuspid, inner cusp slightly curved inwards. Lateral cusp small, not reaching half-length of inner cusp (three times shorter than inner cusp). FIGURE 2.Isbrueckerichthys calvus, holotype, MZUEL 3714, male, 87.3 mm SL. Brazil: State of Paraná: Apucarana: rio Tibagi basin, córrego Juruba. 62 © 2006 Magnolia Press JEREP ET AL.