Australoheros guarani, An, Old Ř Ich Ř Í Č & Kullander, Sven O., 2008

An, Old Ř Ich Ř Í Č & Kullander, Sven O., 2008, The Australoheros (Teleostei: Cichlidae) species of the Uruguay and Paraná River drainages, Zootaxa 1724, pp. 1-51 : 38-40

Australoheros guarani , sp. nov.

( Fig. 16 )

Australoheros sp. ” Paraguay ” (Ř íċan & Kullander, 2006).

Holotype. MHNG 2237.58, 129.1 mm SL, Paraguay, Caaguazú, Río Guyrau-gua, Río Paraná drainage, km 197 on road from Asunción to Stroessner, 12–14. 4. 1985.

Paratypes. 12 specimens, 29.3–100.1 mm SL, all from Paraguay, Río Paraná drainage: NRM 42215, 2, Caaguazú, arroyo crossing at about km 8 on road Caaguazú—Yhú (25°23'15" S, 56°0'35" W). Åhlander et al, 20. 3. 1998; NRM 33498, 2, Itapúa, Arroyo Tembey, 4 km below the falls, Mahnert et al., 1. 11. 1982; MHNG 2582.98, 1, Itapúa, Arroyo Tembey, 4 km below the falls, Mahnert et al., 1. 11. 1982. MHNG 2237.56, 7, 29.3–100.1 mm SL, collected with the holotype.

Diagnosis. A species with unclear affinities among Australoheros species, with the largest scales between the dorsal fin and upper lateral line (only 2 ½ scales vs. 3 ½ or more anteriorly, only one large scale posteriorly). It is most similar to A. facetus , A. minuano and A. cf. facetus , and in coloration patterns also to A. forquilha and A. tembe , all being species with a small and inconspicuous midlateral blotch and a straight midlateral stripe (if present), which runs all along the flank in the limits of E0 and E1 scale rows. It can be clearly separated from A. forquilha and A. tembe in lower meristics, such as 13 caudal vertebrae (vs. 14 or more), a shorter caudal peduncle, shorter scale cover of the dorsal fin, larger (and fewer) scales and a narrower interorbital space.

Description. Based on specimens over 60 mm SL with notes on smaller specimens. Meristic data are summarized in Table 1. Morphometric data are summarized in Table 2 .

Scales ctenoid. Scales on head and chest not distinctly smaller than on flanks. Scales in E0 row 24(7). Upper lateral line scales 16(2), 17(4), 18(1). Lower lateral line scales 6(1), 7(2), 8(2), 9(1). Scales between upper lateral line and dorsal fin 3 anteriorly (or 2 large and 1 smaller), 1 large and one small posteriorly. Scales between lateral lines 2. Circumpeduncular scales 16 (7 dorsally + lateral line scale + 7 ventrally + lateral line scale). Cheek scale rows 3 (1), 4(6). Lower lateral line continued on caudal fin by 1 or 2 scales.

Dorsal fin with one basal scale row appearing from about tenth spine; interradial scales appear from membrane between 16th spine and the first branched ray, along middle of soft portion running partially in double rows. Two last interradial membranes without scales; i.e. 7–8 membranes with interradial scales. Anal fin with one basal scale row; interradial scales in single rows, from posterior of sixth spine, lacking on two last interradial membranes.

TABLE 20. Significantly different values in characters in A. guarani and A. minuano (P <0.05; decreasing order of significance; mean values±SD, proportional measurements in percent).

guarani minuano Preorbital distance in head length 25.6±1.4 16.7±2.4 Head length 32.4±0.7 35.9±1.1 Head width in head length 55.8±1.4 52.4±1.3 Interorbital width in head length 38.7±1.9 33.3±2.4 Ceratobranchial 1 gill rakers 7.0±0.0 6.0±0.5

Pectoral fin rays 13±0.0 12.1±0.4 Obrit diameter in head length 32.2±2.3 35.0±1.6 L2 scales 7.5±1.0 8.8±0.4 Soft dorsal fin pointed, extending slightly beyond middle of caudal fin. D. XV,10 (1), XVI,9 (1), XVI,10 (3), XVII,8 (1). Soft anal fin pointed, of about the same length as dorsal fin. A. VI,8 (5), VII,7 (1). Anal fin pterygiophores 12(5), 13(1). Only one pterygiophor anterior of the first haemal spine. Pelvic fin base below pectoral fin base; first ray longest, extending to first or second anal spine. Pectoral fin with a rounded tip, extending to the first anal spine only. P. 13(7). Caudal fin rounded.

All teeth caniniform, slightly curved. Outer row teeth increasing in size symphysiad, upper jaw anterior teeth longest, lower jaw anterior teeth subequal.

Lower pharyngeal tooth plate in a dissected specimen about one quarter wider than long (length 76% of width) and relatively robust ( Fig. 17 ). Dentigerous area wider than long. 7 teeth along midline, 23 teeth along posterior margin. Posterior teeth tend to be progressively more compressed, except for medial teeth. Larger teeth medially and posteriorly, gradually smaller anteriad and laterad. Posterior teeth with forwards curved posterior cusp and subapical anterior shelf. Large laterally compressed teeth with a second cusp raising anteriorly from shelf.

Gill rakers externally on first gill arch, 2 epibranchial, 1 in angle, 7(6) ceratobranchial.

Vertebrae 13+13=26(6). First caudal vertebra located between 14th and 15th dorsal spines. Caudal peduncle containing only the last halfcentrum (3) or only a half of it (3).

Color pattern in alcohol. All specimens examined show only three abdominal bars without any signs of divisions into four bars.

Color in life. Life colours are unknown. Breeding coloration is also unknown.

Distribution. Australoheros guarani is so far the only Australoheros species known from Paraguay, where it is sparsely distributed in the tributaries of the High Río Paraná ( Fig. 1 ).

Etymology. The species is named after the indigenous Guaraní people.

Notes. Australoheros guarani is most similar to the Argentinian form of A. facetus , much more than to A. cf. facetus . Except for the larger scales between the anterior end of dorsal fin and upper lateral line, it can be distinguished from both these species by a longer dorsal fin scale cover covering the bases of more than seven last dorsal spines (vs. 2–3), by a terminal, slightly down-turned mouth. From both these species as well as from A. minuano , it is best distinguished by a larger preorbital and interorbital distance and in being slightly more deep bodied and having a shorter head. From A. cf. facetus it also differs in having 6 vs 7 (8) anal fin spines (refer to Tables 4, 7 and 20 for exact values).

From both A. facetus and A. cf. facetus , and also A. minuano , it can be distinguished by having only three abdominal bars in all adult specimens and by a different head shape (see paragraph above).

Additionally distinguished from A. facetus in fewer C1 gill rakers and L2 scales (refer to Table 4 for exact values).

It can additionally be distinguished from A. minuano by a larger head width and a smaller orbit, more C1 gill rakers, pectoral fin rays, and L2 scales (refer to Table 20 for exact values) and also in the position of the caudal peduncle bar, which in A. guarani is in the posterior half of the caudal peduncle running through the last two perforated scales of the lower lateral line. In A. minuano , the bar runs through the central portion of the caudal peduncle and is bent anteriorad, so that at least the last scale of the lower lateral line lies outside the bar. The midlateral bar is developed as two pigmented lines running through the central portions of the 0 and E1 scale rows. The posterior portion of the stripe is different from the situation in A. minuano , where posteriorly from the midlateral blotch the stripe is also distinctly developed in the E2 scale row (i.e. a pattern more similar to the A. scitulus group; the pattern of the posterior part of the stripe as observed in A. minuano can be viewed as an intermediate stage between A. guarani and the A. scitulus group). It can also be distinguished from A. minuano in the head shape, which resembles more A. facetus in being sharper, but the mouth is inclined downward like in A. minuano .

Distinguished from the A. scitulus group in lacking the apomorphic color pattern (see description of A. charrua ), by more C1 gill rakers, in head and mouth shape (much larger mouth, differently positioned, especially compared to A. charrua ). In addition distinguished from A. kaaygua by modally 13 pectoral fin rays (vs. 12) and from A. scitulus and A. charrua by 13 caudal vertebrae (vs. 14), fewer anal fin spines (6 vs. 7 or more), by larger scales (fewer scales in both the E1 scale row and between the upper lateral line and the dorsal fin) and additionally from A. scitulus by lacking the characteristic spotted pattern of that species.

Figures

FIGURE 1. Collecting localities of Australoheros guarani and A. facetus (the facetus group). A symbol may cover more than one collecting site.

FIGURE 16. Australoheros guarani. Holotype, MHNG 2237.58, 129.1 mm SL, Río Guyrau-gua, Río Paraná drainage, Paraguay.

FIGURE 17. Lower pharyngeal jaw of a dissected specimen of Australoheros guarani, NRM 33498, in (top to bottom) occlusal, caudal and left lateral aspect.