Hypostomus cochliodon Kner, 1854

Tencatt, Luiz F. C., Zawadzki, Cláudio H. & Froehlich, Otávio, 2014, Two new species of the Hypostomus cochliodon group (Siluriformes: Loricariidae) from the rio Paraguay basin, with a redescription of Hypostomus cochliodon Kner, 1854, Neotropical Ichthyology 12 (3), pp. 585-602 : 587-590

Hypostomus cochliodon Kner, 1854

Figs. 1 , 2 , 3a , 4a , 5a , 6a , 7 , 8

Hypostomus cochliodon Kner, 1854: 265 , Pl. 2 fig. 1, “Rio Cujaba” (= rio Cuiabá). Lectotype NMW 44101, by present designation.

Cochliodon hypostomus Kner, 1854: 265.

Loricaria melanoptera Kner, 1854: 265 .

Diagnosis. Hypostomus cochliodon is distinguished from all other species of Hypostomus , except those belonging to the H. cochliodon group, by having the following unique combination of features: notch between metapterygoid and hyomandibula absent (vs. notch present) and strongly angled dentaries, less than 80° (vs. shallow angle between dentaries, generally more than 80°). Hypostomus cochliodon can be distinguished from the other species of the H. cochliodon group, except from H. dardanelos Zawadzki & Hollanda Carvalho , H. ericae Hollanda Carvalho & Weber , H. ericius Armbruster , H. oculeus (Fowler) , H. paucipunctatus Hollanda Carvalho & Weber , H. pyrineusi (Miranda Ribeiro), H. taphorni (Lilyestrom) and H. waiampi Hollanda Carvalho & Weber by having the opercle almost completely covered by thick layer of skin and exposed region not easily visible (see Fig. 3a ) (vs. externalized opercle and exposed region easily visible, Fig. 3b, c ). It can be distinguished from H. ericae , H. paucipunctatus , and H. waiampi by the absence of buccal papilla (vs. presence); from H. dardanelos , H. ericius , and H. oculeus by the presence of weak to moderately developed keels on lateral plates (vs. strongly developed); from H. pyrineusi by the presence of small black spots closely-set on head and larger, widely spaced spots on trunk, with caudal peduncle generally without spots (vs. uniform spot pattern with head, trunk and fins densely covered by closely-set black spots); from H. taphorni by having both caudal-fin lobes evenly colored (vs. bicolored caudal fin with ventral lobe darker). Hypostomus cochliodon is further distinguished from H. hemicochliodon Armbruster , H. kopeyaka Hollanda Carvalho , Lima & Zawadzki, H. khimaera , H. soniae Hollanda Carvalho & Weber , H. sculpodon Armbruster , and H. weberi Hollanda Carvalho , Lima & Zawadzki by the presence of bicuspid teeth with a large spoon-shaped mesial cusp and inconspicuous lateral cusp that is generally fused to mesial cusp (vs. bicuspid teeth with mesial cusp conspicuously large and round but not spoon-shaped and with distinct lateral cusp). It further differs from H. basilisko and H. khimaera by the absence of a longitudinal dark stripe along midline of flank (vs. presence); from H. levis (Pearson) by the presence of an adipose fin (vs. absence).

Description. Morphometric data in Table 1. Overall view of body in Fig. 2 , juvenile in Fig. 4a . Head broad, moderately deep and slightly compressed. Snout and anterior profile of head pointed in dorsal view. Eye moderate in size, laterally positioned. Dorsal margin of orbit not raised. Greatest body width at cleithrum, decreasing to caudal peduncle. Dorsal profile of head straight from snout tip to vertical through interorbital region, and forming angle of 45° with ventral region of head; convex from that point to dorsal-fin origin; sloped downward to first dorsal caudal-fin procurrent rays, then elevating again to caudal-fin insertion. Ventral profile almost straight from snout tip to insertion of pelvic-fin unbranched ray; slightly straight from pelvic-fin insertion to first ventral caudal-fin procurrent ray, then descending to caudal-fin insertion. Caudal peduncle laterally compressed, ellipsoid on its whole extension. Mesethmoid region rough. Supraoccipital bone with highlydeveloped median ridge; with short posterior process bordered by single plate. Moderate ridge originating lateral to nares, passing through supraorbital, and extending very slightly through superior portion of compound pterotic. Opercle small, almost not exposed and generally not supporting odontodes ( Fig. 3a ). Oral disk round, moderate in size, lower lip not reaching weak-developed odontodes, except on base of dorsal fin and small naked area on snout tip. Predorsal region with slight median keel. These keels slightly diverge posteriorly ( Fig. 6a ). Dorsal and mid-dorsal series of plates with very slight keels. Median series bearing lateral line and without keels. Mid-ventral series angled to fifth or to sixth plate; slightly bent ventrally on caudal peduncle region. Ventral series without keel. Ventral surface of head covered with platelets, with exception of region beneath lower lip. Abdomen covered with minute platelets in specimens larger than 80 mm SL, with exception of very small areas around pectoral- and pelvic-fin insertions and at urogenital opening. Preanal plate present. Median series of plates with 27-29 (mode 28*), three predorsal plates, plates between dorsal and adipose fins 7*-9 (mode 8), plates between adipose and caudal fins 7*-9 (mode 8); plates below dorsal-fin base 7-8* (mode 7).

Dorsal fin II,7, its origin at vertical through midpoint between pectoral and pelvic fins, or slightly posterior to that point. Dorsal-fin distal margin straight; dorsal-fin ray tips not reaching adipose spine. Adipose-fin spine compressed and curved inward. Pectoral fin I,6, its distal border straight. Pectoral-fin spine slightly curved inward, covered with moderately developed odontodes, more developed on its distal portion and in larger specimens. Tip of adpressed pectoral fin reaching to basal one-third of adpressed pelvic-fin spine. Pelvic fin i,5, its distal border convex; its adpressed unbranched ray surpassing anal-fin origin. Anal fin i,4, its tip reaching fifth to sixth plate after its origin. Rays of anal fin progressively increasing in size posteriorly, third branched ray generally longest. Caudal fin i,14,i, its margin falcate, with both lobes similar in length.

transversal through gill openings ( Fig. 5a ); ventral surface covered with numerous small papillae decreasing in size posteriorly. Maxillary barbel slightly smaller than eye diameter. Odontodes present on anterior surface of upper lip, just below snout. Buccal papilla (sensu Armbruster, 2003) absent. Dentaries acutely angled, averaging less than 80° between left and right dentary rami.Seven to 9 (mode 7, lectotype 8) teeth in premaxilla, 7 to 9 (mode 8, lectotype 7) in dentary. Teeth spoon-shaped, bicuspid with lateral cusp very reduced or fused to mesial cusp (see Armbruster, 2003, fig. 1c). Juveniles, up to 80 mm SL, with villiform bicuspid teeth, similar to those in most species of Hypostomus (see Armbruster, 2003, fig. 1c).

Body dorsally covered with five rows of dermal plates with Color in alcohol. Ground color of head and trunk grayish brown; ventral surface of body yellowish brown. Spots at least in some part of body and fins in all specimens. Presence of many small dark spots on head, mainly on top of head and compound pterotic; spots on trunk sparce, more faded and generally larger than those in head and widely spaced ( Fig. 7a ) in some specimens from rio Paraguay basin. Spots closely spaced on ventral surface of body in some specimens from rio Paraguay basin. Caudal peduncle generally without spots. All fins with spots on spines, unbranched and branched rays and membrane. Proximal region of fins with same color to ventral surface of body, becoming dark brown towards distal portions ( Fig. 7b ) in some larger specimens from both rios Paraguay and Paraná basins; uniform ground color on fins in some specimens. Larger and more widely spaced spots on dorsal portion of body and head; spots generally more closely spaced on ventral surface of body in some specimens from upper rio Paraná basin.

Color in life. Color pattern of live specimens is very similar to that of preserved ones ( Fig. 8 ).

Sexual dimorphism. No sexual dimorphism was observed.

Distribution. Hypostomus cochliodon is known from the rio

Paraguay basin, as well as from the middle and upper rio Paraná basins ( Fig. 9 ). In the upper rio Paraná basin, it is known from downstream of the Porto Primavera reservoir, which is the first reservoir upstream of the Itaipu reservoir, suggesting that the species colonized this region after the flooding of the Sete Quedas falls by the construction of the Itaipu reservoir in 1982. No records of the species in the upper rio Paraná are known before this period.

Material examined. 166 specimens. Brazil. Mato Grosso. MNRJ 28048, 2, 105.8- 145.7 mm SL; NUP 3602, 1, 150.5 mm SL; NUP 10807, 1, 208.0 mm SL; NUP 12003, 1, 186.9 mm SL; NUP 12671, 1, 193.1 mm SL; and NUP 13421, 1, 154.4 mm SL, rio Manso. MZUSP 26803, 4, 147.1- 183.2 mm SL, rio Coxipó. MZUSP 36728, 1, 231.6 mm SL, rio Piquiri. MZUSP 38185, 1, 191.7 mm SL, mouth of the rio Varadouro. MZUSP 56757, 1, 173.0 mm SL, rio Cuiabá. NMW 44101, 1, 182.5 mm SL, “Rio Cujaba” (= rio Cuiabá), lectotype of Hypostomus cochliodon Kner , by present designation. NMW 46277, 1, 153.0 mm SL; and NMW 59395, 1, 210.0 mm SL, paralectotypes of Hypostomus cochliodon Kner. NUP 903, 7, 20.5- 185.1 mm SL; NUP 9619, 28, 20.0- 71.8 mm SL; NUP 12001, 1, 202.8 mm SL; NUP 12498, 6, 76.2-88.3 mm SL; and NUP 13271, 1, 221.6 mm SL, Manso Reservoir. NUP 3257, 1, 203.9 mm SL, rio Casca. NUP 11931, 2, 53.6-53.8 mm SL; and NUP 13833, 1 c&s, 69.2 mm SL, córrego Descalvado. NUP 11936, 6, 46.6-53.7 mm SL, córrego Cambará. NUP 11956, 5, 38.6-92.8 mm SL, córrego Palmeira. NUP 12000, 2, 155.8- 174.1 mm SL; NUP 12002, 1, 219.5 mm SL; NUP 12017, 1, 157.8 mm SL; NUP 12071, 2, 145.5- 151.3 mm SL; and NUP 12670, 1, 155.5 mm SL, rio Cuiabá. NUP 12069, 2, 125.5- 151.5 mm SL; and NUP 13479, 5, 49.0- 160.8 mm SL, córrego Cancela. NUP 13488, 1, 123.0 mm SL, rio Jangada. Mato Grosso do Sul. FMNH 108106, 1, 146.0 mm SL; and FMNH 108113, 8, 31.0- 65.6 mm SL, rio Paraguay. FMNH 108116, 1, 92.0 mm SL, rio Apa. FMNH 108588, 4, 35.0-51.0 mm SL, córrego do Engano. NUP 9341, 6, 37.2-60.7 mm SL, córrego Feio. NUP 9822, 6, 26.8-143.0 mm SL; and NUP 10806, 7, 41.2-128.2 mm SL, córrego da Onça. NUP 10809, 2, 165.0- 215.8 mm SL; NUP 13282, 1, 195.2 mm SL; and NUP 13283, 3, 184.4- 252.1 mm SL, rio Ivinheima. NUP 12074, 2, 166.3- 186.5 mm SL, rio Taquari. NUP 12145, 1, 157.8 mm SL, canal Ipoitã. NUP 12146, 1, 157.0 mm SL; NUP 12768, 1, 241.1 mm SL; and NUP 13279, 3, 170.7- 190.6 mm SL, canal Curutuba. NUP 13495, 1, 62.0 mm SL, stream tributary to rio Aquidauana. NUP 13496, 10, 35.2-89.8 mm SL, ribeirão Salobra. ZUFMS-PIS 3087, 2, 205.2- 207.8 mm SL, rio Vacaria. ZUFMS-PIS 3093, 1, 210.0 mm SL; and ZUFMS-PIS 3094, 1, 136.2 mm SL, córrego Salobrinha. Paraná State. NUP 2556, 8, 154.1- 238.4 mm SL; and NUP 4074, 1, 127.6 mm SL, Itaipu Reservoir. NUP 2571, 1, 147.8 mm SL; and NUP 13284, 1, 235.9 mm SL, rio Paraná. NUP 4506, 1, 135.7 mm SL, arroio Guaçu. NUP 13541, 2, 115.0-125.0 mm SL, rio Iguaçu. Unknown locality. CAS 102213, 1, 83.0 mm SL, locality listed only as Brazil. Paraguay. Concepción. MCP 10978, 1, 191.1 mm SL, arroyo Tagatija-Guazu.

Figures

Fig. 1. Hypostomus cochliodon, lectotype, NMW 44101, 182.5 mm SL, rio Cuiabá, in lateral view.

Fig. 2. Hypostomus cochliodon, NUP 10807, 208.0 mm SL; dorsal (top), lateral (middle), and ventral (bottom) views.

Fig. 3. Opercle morphology of (a) Hypostomus cochliodon, NUP 10809, 215.8 mm SL, showing indistinct opercle without odontodes; (b) Hypostomus basilisko, holotype, MZUSP 111110, 182.5 mm SL and (c) Hypostomus khimaera, holotype, MZUSP 111129, 139.1 mm SL, showing layer of skin surrounding opercle that supports odontodes.

Fig. 4. Lateral view of juvenile in (a) Hypostomus cochliodon, NUP 11956, 92.8 mm SL, (b) Hypostomus basilisko, paratype, ZUFMS-PIS 3083, 64.2 mm SL and (c) Hypostomus khimaera, NUP13494,68.8 mmSL.

Fig. 5. Mouth and teeth of (a) Hypostomus cochliodon, NUP 10807, 208.0 mm SL, showing one series of papillae in inner face of upper and lower jaws; (b) Hypostomus basilisko, holotype, MZUSP 111110, 182.5 mm SL, showing the agglomerated papillae on inner face of upper and lower jaws; and (c) Hypostomus khimaera, MZUSP 111129, holotype, 139.1 mm SL, showing weakly developed papillae not forming series.

Fig. 6. Keels, ridges and odontodes of (a) Hypostomus cochliodon, NUP 10807, 208.0 mm SL, showing two weakly developed ridges in compound pterotic, weakly developed keels, few and weakly developed odontodes and predorsal keels weakly developed; (b) Hypostomus basilisko, holotype, MZUSP 111110, 182.5 mm SL, showing the three ridges on top of head, strongly developed keels, numerous welldeveloped odontodes on plates covering body and head and strong V-shaped predorsal keels; (c) Hypostomus khimaera, holotype, MZUSP 111129, 139.1 mm SL, showing moderately developed keels and dermal plates supporting moderately developed odontodes.

Fig. 7. Spots and color pattern of fins in Hypostomus cochliodon; (a) NUP 12071, 151.1 mm SL, showing spots smaller and closely spaced on head and larger and widely spaced on the body; (b) NUP 12768, 241.1 mm SL, the base of fin with same color of body, becoming dark brown in tip; and uniform spot pattern in ventral portion of body.

Fig. 8. Color pattern of live specimen of Hypostomus cochliodon (uncatalogued specimen) from córrego da Onça, Mato Grosso, rio Paraguay basin.

Fig. 9. Type locality of Hypostomus basilisko (yellow star), Hypostomus cochliodon (dark star) and Hypostomus khimaera (red star). The dark triangles represent areas of co-occurrence of Hypostomus cochliodon and Hypostomus khimaera; dark diamonds represent area of occurrence of Hypostomus cochliodon in the upper rio Paraná basin.