Crenicichla taikyra, Casciotta, Jorge, Almirón, Adriana, Aichino, Danilo, Gómez, Sergio, Piálek, Lubomír & Říčan, Oldřich, 2013

Casciotta, Jorge, Almirón, Adriana, Aichino, Danilo, Gómez, Sergio, Piálek, Lubomír & Říčan, Oldřich, 2013, Crenicichla taikyra (Teleostei: Cichlidae), a new species of pike cichlid from the middle río Paraná, Argentina, Zootaxa 3721 (4), pp. 379-386 : 380-383

Crenicichla taikyra sp. n.

Figs. 1–5 , Table 1

Crenicichla sp. 'Paraná'—Piálek et al. 2012 [inclusion in molecular phylogeny; MACN-ict 9466, Corrientes province, río Paraná at Ituzaingó, 27°30'04.3"S 56°42'41.6"W]

Holotype. MACN-ict 9461, 98.3 mm, Argentina, Misiones province, río Paraná at Candelaria, 27º21’43.0”S 55º51’54.7”W, Feb 1999, Aichino D. ( Fig. 1 ).

Paratypes. All from Argentina. MACN-ict 9462, 3 ex., 83.9–107.0 mm, Misiones province, río Paraná at Candelaria, 27º21’43.0”S 55º 51’54.7”W, Nov 2008, Aichino D. MACN-ict 9463, 7 ex., 78.2–111.4 mm, same data as holotype. MACN-ict 9464, 4 ex., 97.7–115.6 mm, Misiones province, río Paraná at Posadas, 27º21’43.0”S 55º51’54.7”, Nov 1999, Aichino D. MACN-ict 9465, 4 ex., 56.2–71.4 mm, Corrientes province, río Paraná at Ituzaingó, 27°30'04.3"S 56°42'41.6"W, May 2007, Casciotta et al. MACN-ict 9466, 13 ex., 49.6–101.0 mm, Corrientes province, río Paraná at Ituzaingó, 27°30'04.3"S 56°42'41.6"W, Nov 2009, Casciotta et al. AI 306, 3ex., 70.4–97.2 mm, Corrientes province, río Paraná at Yahape, 27º22’12.1”S 57º39’14.6”W, Nov 2008, Casciotta et al. AI 264, 4 ex. (C&S), 39.3–76.0 mm, Corrientes province, río Paraná at Ituzaingó, 27°30'04.3"S 56°42'41.6"W, May 2008, Casciotta et al. MLP 10398, 5 ex., 50.0– 67.6 mm, Corrientes province, río Paraná at Ituzaingó, 27°30'04.3"S 56°42'41.6"W, Nov 2009, Casciotta & Almirón

Diagnosis. Crenicichla taikyra is distinguished from all remaining species of Crenicichla except C. jurubi , C. semifasciata , and C. yaha by having a stout lower pharyngeal tooth plate with molariform teeth (vs. slender pharyngeal tooth plate without molariform teeth).

Crenicichla taikyra differs from C. jurubi in having a serrated vs. smooth preopercle, a well developed suborbital stripe vs. suborbital stripe absent or reduced to a spot at margin of orbit, and by the absence vs. presence of scattered dots on back and sides. Crenicichla taikyra differs from C. semifasciata in having an ascending arm of the premaxilla longer (vs. shorter than the dentigerous one), caudal fins subtruncated (vs. deeply rounded), caudal fin scaled only on its basal third (vs. mostly scaled), caudal spot without light ring (vs. caudal spot surrounded by a silvery or orange ring), and a narrower interorbital width (17.1–23.3% vs. 32.0–40.0% of HL). Finally, Crenicichla taikyra can be distinguished from C. yaha by having a stouter lower pharyngeal tooth plate with about 16 molariform teeth ( Fig. 2 a) (vs. about 4 molariform teeth; Fig. 2 b), and absence of microbranchiospines on gill arches (vs. presence).

Other characters besides the presence of molariform teeth on lower pharyngeal jaw separate C. taikyra from other species inhabiting the río Paraná basin: C. taikyra differs from C. iguassuensis and C. tesay in having isognathous jaws vs. lower jaw prognathous. Crenicichla taikyra is different from C. hu in having a colour pattern with a gray or olive green background vs. dark brown to black, and E1 row scales 54–60 vs. 47–54. Crenicichla taikyra can be distinguished from C. mandelburgeri in having more scales in E1 row scales (54–60 vs. 44–56), jaws isognathous vs. lower jaws prognathous, and absence of lateral band in adults vs. presence. Crenicichla taikyra has isognathous jaws and the blotches on flanks placed below the upper lateral line whereas C. ypo has a lower jaw slightly prognathous and the blotches are extending 3 to 4 scale rows above and below lateral line. Crenicichla taikyra lacks brown dots on each lateral line scale and lateral band on flanks, which are present in C. haroldoi . The absence of a lateral band distinguishes C. taikyra from C. jaguarensis . Crenicichla jupiaensis differs from C. taikyra in having the suborbital stripe reduced to a few spots posterior to the orbit, a thin black line on the posterior margin of preoperculum, cheek naked, and numerous vertical stripes. Crenicichla lepidota and C. britskii have a humeral spot absent in C. taikyra . Crenicichla scottii has parallel and thin longitudinal bands and C. gillmorlisi has small dark dots all over the sides, features not present in C. taikyra . Crenicichla vittata has 78–85 in E1 row scales, lateral band, and a particular colour pattern on top of the head forming a crown design whereas C. taikyra has 54–60 E1 row scales, absence of lateral band, and the pattern of pigmentation on head described above.

Description. Body elongate. Head deeper than wide. Snout short, bluntly pointed in lateral view. Mouth small and narrow, upper and lower jaws isognathous. Tip of maxilla usually not reaching anterior margin of orbit. Lower lip folds widely separated anteriorly. Nostrils dorsolateral, nearer anterior margin of orbits than snout tip. Posterior margin of preopercle serrated. Scales on flanks strongly ctenoid. Head scales cycloid. Predorsal scales small, superficially embedded in skin. Prepelvic scales smaller than predorsal ones. Interopercle naked. Cheek scaled, 4 to 5 scale series below eye. Scales in E1 row: 54(2), 55(1), 56(7), 57(5*), 58(3), 60(3). Scales in transverse row: 9/ 14(2), 10/13(3), 10/14(7), 10/15(3), 10/16(2), 11/13(1), 11/14(2*), 12/14 (1). Two (17) or three (4) scale rows between lateral lines. Upper lateral line scales: 21(1), 23(3), 24(9*), 25(7), 26(1). Lower lateral line scales: 8(1), 9(3), 10(13*), 11(2), 13(2). Dorsal, anal, pectoral, and pelvic fins naked. Dorsal fin: XX,10(2); XX,11(1); XX,12(1); XXI,10(1); XXI,11(12); XXI,12(2); XXII,10 (1); XXII,11(1*). Anal fin: III,7(1); III,8(20*). Pectoral fin 15(10), 16(10*), 17(1). Caudal-fin squamation not reaching half of caudal fin length. Tip of soft-dorsal fin rounded or pointed, surpassing caudal-fin base. Tip of anal fin usually not reaching caudal-fin base, reaching in 5 specimens. Caudal fin slightly rounded. Pectoral fin rounded, not reaching tip of pelvic fin. No microbranchiospines on gill arches (4 C&S). Gill rakers externally on first gill arch: 1–2 on epibranchial, 1 on angle, and 6 on ceratobranchial. Absence of patches with unicuspidate teeth on fourth ceratobranchial (4 C&S). Lower pharyngeal tooth plate stout, bearing molariform, unicuspid, and few bicuspid crenulated, curved anteriorly teeth restricted to horn bases ( Fig. 2 a). Upper pharyngeal tooth plates with unicuspidate and molariform teeth. Frayed zone bearing one concavity with small unicuspid teeth (4 C&S). Premaxillary ascending process longer than the dentigerous one. Premaxilla with 19–21(2) unicuspid teeth on outer row, larger than inner ones. Four teeth rows near symphysis. Dentary with 23–24(2) unicuspid teeth in outer row, 4 rows near symphysis. Teeth of outer row in premaxilla and dentary, slightly movable, inner ones fully depressible. Total vertebrae 35–36(4 C&S).

Colour in alcohol. Background of body pale gray or olive green. Preorbital stripe between snout tip and anterior margin of orbit, gray. Postorbital stripe between posterior margin of orbit to opercle distal margin, deep gray. Suborbital stripe black and composed of dots, one to five dots wide, usually not reaching ventral margin of cheek (13). Flanks with 5 to 7 quadrangular dark blotches, reaching faintly dorsal-fin base. Posteriormost blotch extending onto caudal peduncle. Dorsal, anal, and caudal fins, smoky; adults with some dark dots on middle caudal fin. Pectoral and pelvic fins pale yellowish. Females with a dark and wide longitudinal stripe limited below and above by a narrow white stripe on distal region of dorsal fin. Caudal spot black and subcircular, well separated from base of fin, just above of midline of caudal fin. Juveniles (55.6–69.4 mm SL) with vertical bars on flanks and scattered dots on dorsal, anal and caudal fins.

Colour upon capture. Colours not greatly different from coloration in alcohol, background of body pale gray or olive green ( Fig. 3 ). Dorsal, anal, and caudal fins pale gray or olive green. Pectoral fin hyaline, pelvic fin pale gray.

Etymology. The species epithet taikyra is a combination of Guaraní words tãi (tooth) and kyra (thick) referring to the thick molariform teeth and the stout lower pharyngeal tooth plate of the species.

Distribution. Crenicichla taikyra was found in the middle río Paraná in Misiones and Corrientes Provinces, Argentina ( Figs. 4–5 ).

Habitat. Below the Yacyretá Dam the specimens were collected in stony environment. Secchi disk 212 mm, water temperature 25.1ºC, pH 7.14, conductivity 51.4 µS cm -1, dissolved oxygen 8.2 mg l -1(99.7% saturation), alkalinity 9.0 mg l -1.

Stomach contents. The two specimens examined contained snails ( Potamolithus sp. and Limnoperna fortunei ) and remains of fishes.

Figures

FIGURE 1. Crenicichla taikyra, holotype, MACN-ict 9461, 98.3 mm, Argentina, Misiones province, río Paraná at Candelaria.

FIGURE 2. Lower pharyngeal tooth plate in occlusal view. a. C. taikyra, AI 264, 77.0 mm SL. b. C. yaha, AI 315, 77.6 mm SL. Scale bar: 1 mm.

FIGURE 3. Crenicichla taikyra, paratype, live specimen, MACN-ict 9466, 74.9 mm, Argentina, Corrientes province, Ituzaingo city.

FIGURE 4. Distribution of Crenicichla taikyra in the río Paraná in Argentina. 1 — Candelaria (type locality), 2 — río Paraná at Posadas, 3 — Ituzaingó city, and 4 — Yahapé city. The number 12 inside the circle corresponds to national route 12.

FIGURE 5. Río Paraná at Candelaria, type locality of Crenicichla taikyra.

Tables

TABLE 1. Proportional measurements in percents of standard length of holotype and 20 paratypes of Crenicichla taikyra sp. n. SD = standard deviation.

	Holotype Range	Mean SD
Standard length (mm)	98.3 71.3–115.6
Head length	32.6 30.0–33.4	32.3 0.96
Snout length	13.7 11.7–13.7	12.1 0.86
Head depth	18.1 16.2–19.4	17.3 0.79
Body depth	22.3 20.8–23.8	22.1 0.90
Orbital diameter	6.5 6.2–7.7	6.7 0.44
Interorbital width	6.7 5.7–7.5	6.7 0.50
Pectoral fin length	20.2 18.0–21.3	19.9 0.90
Caudal peduncle depth	11.8 11.2–12.7	11.8 0.43
Caudal peduncle length	15.4 14.0–16.5	15.0 0.68