Crenicichla ypo, Casciotta & Almirón & Piálek & Gómez & Rícan, 2010

Casciotta, Jorge, Almirón, Adriana, Piálek, Lubomír, Gómez, Sergio & Rícan, Oldrich, 2010, Crenicichla ypo (Teleostei: Cichlidae), a new species from the middle Paraná basin in Misiones, Argentina, Neotropical Ichthyology 8 (3), pp. 643-648 : 644-647

Crenicichla ypo , new species

Figs. 1-4

Holotype. MACN-ict 9431, 105.5 mm SL, Argentina, Misiones , Paraná basin, arroyo Urugua-í, at Establecimiento “Alto Paraná”, approx. 25º57.9’S 54º06.5’W, Feb 1986, Gómez et al.

Paratypes. All from Argentina, Misiones , Paraná River basin.AI 212, 4, 102.0-130.0 mm SL, arroyo Falso Urugua-í, 25º58’26.2”S 54º15’28.5”W, Nov 2007, Casciotta et al. AI 263, 1 c&s, 95.3 mm SL, arroyo Urugua-í basin, arroyo Grapia, 6 km north from Colonia Gobernador J. J. Lanusse, approx. 25º52.2’S 54º10.4’W, Nov 1986, Gómez et al. MACN-ict 9432, 3, 101.0-116.0 mm SL, arroyo Urugua-í basin, arroyo Grapia, 6 km north from Colonia Gobernador J.J.Lanusse, approx. 25º52.2’S 54º10.4’W, Nov 1986, Gómez et al. MACN-ict 9433, 1, 133.0 mm SL, arroyo Uruzú at route 19, Parque Provincial Islas Malvinas, approx. 25º56.3’S 54º13.0’W, Sep 1986, Gómez et al. MACN-ict 9434, 1, 111.0 mm SL, arroyo Urugua-í and route 19, Parque Provincial Islas Malvinas, approx. 25º56.3’S 54º13.0’W, Feb 1986, Gómez et al. MACN-ict 9435, 1, 137.0 mm SL, arroyo Urugua-í and route 19, Parque Provincial Islas Malvinas, approx. 25º56.3’S 54º13.0’W, Sep 1986, Gómez et al. MACN-ict 9436, 1, 123.0 mm SL, arroyo Urugua-í in Isla Palacio, approx. 25º52.8’S 54º24.0’W, Feb 1986, Gómez et al. MACN-ict 9437, 1, 123.0 mm SL, same data as holotype.MACN-ict 9438, 3, 89.8-109.0 mm SL, arroyo Falso Uruguaí, 25º58’26.2”S 54º15’28.5”W, Nov 2007, Casciotta et al .

Diagnosis. The new species is recognized in the Paraná River basin by the following combination of characters: 6 to 8 irregular blotches along the upper lateral line, absence of scattered dark spots on flanks, low number (47-55) of E1 scales, and a slightly prognathous lower jaw. Females have a distinctive coloration of the dorsal fin, with a wide black longitudinal stripe on the distal portion with an equally wide red stripe below it.

Crenicichla ypo lacks the humeral spot present in C. britskii and C. lepidota . Lateral line scales in C. ypo are without brown dots such as are present on each scale in C. haroldoi . Numerous scattered dark spots on flanks are absent in C. ypo that distinguishes this species from C. iguassuensis and C. tesay . Crenicichla ypo has a distinct caudal spot, inconspicuous or absent in C. jaguarensis . Crenicichla ypo lacks the lateral stripe displayed in C. jaguarensis , C. mandelburgeri , and C. vittata .

Crenicichla ypo differs from C. jupiaensis in having lower jaw slightly prognathous, having a well-developed suborbital stripe composed of spots, and the cheek bearing up to 8 scale rows vs. isognathous jaws, a suborbital stripe reduced to a few spots posterior to the orbit, and a naked cheek.

Crenicichla ypo does not bear well developed vertical bars which are reduced to irregular blotches. This distinguishes this species from those with complete vertical bars: C. jupiaensis , juveniles of C. mandelburgeri , and C. niederleinii .

Crenicichla ypo differs from C. niederleinii and C. vittata in having a low number of E1 scales (47-55 vs. 56-65 and 78- 85, respectively).

Parallel and thin longitudinal stripes are absent in C. ypo vs. present in C. scottii .

Crenicichla ypo is easily distinguished from C. semifasciata in having the ascending arm of the premaxilla longer than the dentigerous one, the blotches on flanks including the upper lateral line and extending 3 to 4 scale rows above and below it, and having about half of the caudal fin scaled vs. ascending arm of the premaxilla shorter than the dentigerous one, the flanks bearing quadrangular blotches placed below the upper lateral line or lateral band, and caudal fin scaled in most of its surface.

The new species differs from C. yaha in having the lower jaw slightly prognathous and head depth 14.5-17.6% of SL vs. isognathous or upper jaw slightly prognathous and head depth 17.9-20.8%of SL.Females of C. ypo are distinguished from females of C. yaha by having dorsal fin with a wide black stripe above a red stripe vs. dorsal fin with a wide black irregular stripe.

Description. Body elongate, depth 4.2 to 4.8 times in SL. Head as deep as wide or slightly deeper. Snout short, bluntly pointed in lateral view, 2.5 to 3.0 times in head length. Lower jaw slightly prognathous. Tip of maxilla reaching anterior margin of orbit in most specimens. Lower lip widely interrupted medially. Nostrils dorsolateral, close to anterior margin of orbit (12; MACN- ict 9431, 9432, 9434, 9435, 9437, 9438,AI 212, AI 263) or close to snouttip (5; MACN-ict9432, 9433, 9436,AI 212).Posteriormargin of preopercle serrated (12; MACN-ict 9431, 9432, 9433, 9434, 9435, 9437, 9438,AI 212, 263), or smooth on one or both sides (6; MACN-ict 9432 right side, MACN-ict 9436 both sides, MACNict 9438 left side, AI 212 right side); variation of the last two characters does not display any biogeographical pattern. Scales on flank strongly ctenoid. Head scales cycloid. Predorsal scales small, superficially embedded in skin. Prepelvic scales smaller than predorsal ones. Interopercle naked. Cheek scaled, 5 to 8 scales below eye embedded in skin. Scales in E1 row 47(2*), 48(1), 51(3), 53(5), 54(3), 55(3). Scales in transverse row 9/15(1), 10/14(1), 10/15(3), 10/16(3), 11/14(1), 11/15(6*), 11/16(2). Three scale rows between lateral lines. Upper lateral line scales 20(1), 21(2), 22(1), 23(4*), 24(1), 25(7), 27(1). Lower lateral line scales 1(1),5(1),9(1),10(2),11(6),12(4*),13(1),14(1).Dorsal,anal,pectoral and pelvic fins naked.Dorsal fin XX,10(1), XXI,10(2), XXI,11(3), XXI,12(1), XXII,10(3), XXII,11(5*), XXII,12(1).AnalfinIII,7(1), III,8(13*),III,9(3).Pectoralfin15(1),16(16*).Caudal-finsquamation not reaching the middle of fin. Soft-dorsal fin rounded or pointed, extending beyond caudal-fin base. Tip of anal fin usually not reaching caudal-fin base (reaching in 4; MACN-ict 9431, 9432, 9433,AI 212).Caudal fin rounded.Pectoral fin rounded, reaching the tip of pelvic fin. Microbranchiospines present on second through fourth gill arches. Gill rakers externally on first gill arch: 3 on epibranchial, 1 on angle, and 8 on ceratobranchial. Two to five patches of unicuspid teeth on fourth ceratobranchial. Lower pharyngeal tooth plate with unicuspid recurved and curved crenulated bicuspid teeth, those of posterior and medial row larger than remaining ones ( Fig. 4 ). Upper pharyngeal tooth plate with unicuspid and bicuspid teeth. Frashed zone bearing one concavity with small unicuspid teeth. Premaxillary ascending process longer than dentigerous process. Premaxilla with 20(1) unicuspid teeth on outer row, larger than inner ones. Five tooth rows near symphysis. Dentary with 25(1) unicuspid teeth on outer row, four rows near symphysis. Total vertebrae: 37 (1 c&s). Premaxillary and dentary outer row teeth slightly movable, inner ones fully depressible.

Colour upon capture. Background colour of body grey. Deep grey preorbital stripe between anterior margin of orbit and snout tip, visible only in small specimens. Postorbital stripe between posterior margin of orbit and preopercle or opercle

646 A new species of Crenicichla from the middle Paraná basin

distal margin deep grey. Suborbital stripe black almost reaching ventral margin of cheek; wide and fragmented (up to eight dots wide). Flanks with 6 to 8 irregular black blotches below (up to four scales) and above (up to three scales) upper lateral line, marginally reaching dorsal-fin base. Posteriormost blotch not extending onto caudal peduncle. Dorsal, anal, and caudal fins pale grey, males with numerous dark scattered dots on dorsal, anal, and caudal fins, ( Fig. 2 ) which are absent or rarely seen in females. Caudal fin with a black subcircular spot, in some specimens bearing an irregular white ring, just above of midline of caudal fin. Pectoral and pelvic fins pale grey. Some male specimens with several irregular orange dots on flank at level and behind pectoral fin ( Fig. 2b ).

Females with head, upper half of flank, and caudal fin deep grey. Yellow and orange pigment on flank at level and behind pectoral fin. Dorsal and anal fins of females lacking small dark dots, few of them present on caudal fin. Females with a distinctive coloration of the dorsal fin, with a wide black longitudinal stripe on the distal region of dorsal fin and an equally wide red stripe below it ( Fig. 3 ).

Colour in alcohol. Similar to that of live specimens with a tendency to become pale. Conserved specimens lack the carotenoid pigments, such as orange dots on flank of males, yellow or orange area on flank of females, and wide red stripe in dorsal fin of females. Distribution. Crenicichla ypo is found in the arroyo Uruguaí basin, middle Paraná River basin, Misiones province, Argentina ( Figs. 5-6 ).

Etymology. The specific epithet ypo , is a Mbya Guaraní word y po that means water dweller.

Habitat. Crenichla ypo was collected both before and after the Urugua-í hydroelectrical dam was built in 1989 (see material);

Holotype Range Mean SD Standard length (mm) 105.5 89.8-137.0 - - Head length 34.6 32.0-34.6 33.2 0.76 Snout length 11.5 10.8-12.8 11.8 0.64 Head depth 15.6 14.5-17.6 16.0 0.97 Body depth 21.1 20.5-23.9 22.3 1.05 Orbital diameter 6.6 5.7-7.1 6.4 0.37 Interorbital width 6.8 6.2-7.9 7.1 0.50 Pectoral-fin length 19.7 18.7-22.0 20.1 0.84 Caudal-peduncle depth 12.3 10.9-12.9 12.1 0.60 Caudal-peduncle length 15.4 14.3-16.7 15.5 0.55

the species presently occurs also directly in the reservoir (pers. obs.). The arroyo Urugua-í is a moderately fast flowing river with tributaries of an average depth of 1 m outside of the dam influence. Macrophytes such as Echinodorus uruguayensis Arechavaleta and Potamogeton pseudopolygonus Hagström are present. The bottom consists of mud, sand with gravel and/or bedrock. After dam construction some parts of impoundment lake are up to 6 m deep and some previous localities like Isla Palacio are below the water surface. Crenicichla ypo is sympatric with C. yaha and one additional undetermined Crenicichla species (pers. obs.).

Figures

Fig. 1. Crenicichla ypo, holotype, MACN-ict 9431, 105.5 mm SL. Argentina, Misiones, arroyo Urugua-í.

Fig. 2. Crenicichla ypo, AI 212, live male paratypes: a) 113.1 mm SL; b) detail of the orange dots on flank; and c) 102.7 mm SL, showing a spotted dorsal fin.

Fig. 3. Crenicichla ypo, MACN-ict 9438, 104.0 mm SL, female, paratype: a) a freshly collected specimen damaged from gillnets; b) detail of the dorsal fin showing the diagnostic black-red stripe pattern of females.

Fig. 4. Crenicichla ypo,AI 263, 95.3 mm SL, lower pharyngeal tooth plate in occlusal view. Scale bar = 1 mm.

Fig. 5. Arroyo Falso Urugua-í, one of the paratype localities of Crenicichla ypo.

Fig. 6. Distribution of Crenicichla ypo in the Province of Misiones, Argentina. 1- Isla Palacio, 2- Parque provincial Isla Malvinas, 3- ArroyoGrapia andArroyo Uruzú, 4- Establecimiento “Alto Paraná” (type-locality), and 5- Arroyo Falso Urugua-í.