Australoheros minuano, 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 : 35-38

Australoheros minuano , sp. nov.

( Fig. 15 )

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

Holotype. MCP 12710 C, 70.8 mm SL, Brazil, Rio Grande do Sul, Arroyo Canoin, Rio Uruguai drainage, road from Pirapo to São Nicolau. 2 November 1988. C. Lucena, L. Bergmann, E. Pereira, and P. Azevedo.

Paratypes. 85 specimens, all from Brazil, Rio Grande do Sul: MCP 12710 A-I, 7, 34.7–83.9 mm SL, collected with the holotype; MCP 12724, 42, Brazil, Rio Grande do Sul, Arroyo Paso do Alto, Rio Uruguai drainage, 5 November 1988. C. Lucena, L. Bergmann, E. Pereira, P. Azevedo and A. Ramírez; MCP 11227, 24, Brazil, Rio Grande do Sul, Arroyo Garupa, divisa Quarai / Alegrete, Rio Uruguai drainage, 12 November 1988. C. Lucena, L. Bergmann, and P. Azevedo; MCP 11216, 12, Brazil, Rio Grande do Sul, Arroyo Quarai- Mirim, estrada Quarai-Alegrete, Rio Uruguai drainage, 12 November 1988.

Diagnosis. A relatively elongated species, reaching more than 120 mm TL. Most similar to A. facetus , A. cf. facetus , A. kaaygua and A. guarani . Distinguished from all species except A. kaaygua in having a modal count of 12 pectoral fin rays. Distinguished from A. facetus , A. cf. facetus and A. guarani by having modally 6 C1 gill rakers. Also distinguished from A. facetus and A. cf. facetus in not having an upwards directed mouth and a longer dorsal fin scale cover, covering bases of 7–8 last spines (vs. only 2–3) ( Fig. 9 ). Similar to A. kaaygua in having yellowish ground color, but without the red corners of caudal fin typical for A. kaaygua , and also distinguished by being much less deep-bodied. Distinguished from all Australoheros species by pink to red dominant males.

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 .

Mouth is isognathous, somewhat downwards directed. The outline of the head when mouth closed distinctly rounded (see Fig. 12 ).

Scales in E0 row 24(7), 25(1). Upper lateral line scales 16(5), 17(2). Lower lateral line scales 8(2), 9(6). Scales between upper lateral line and dorsal fin 3 large and one small anteriorly, two large and one small posteriorly up to the 12th spine, than one 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 4 (3). 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. Dorsal fin with one basal scale row appearing from about ninth spine; interradial scales appear from fourteenth spine membrane, running in single rows. Two last interradial membranes without scales. Anal fin with one basal scale row; interradial scales in single rows, from penultimate or seventh spine, lacking on two last interradial membranes.

D. XVI,9 (1), XVI,10 (7). A. VI,8 (2), VI,9 (4), VII,8 (3). Anal fin pterygiophores 12(2), 13(7). One (7) or two (2) pterygiophores anterior of the first haemal spine. Pelvic fin base below pectoral fin base; first ray longest, extending to the first anal fin spine. Pectoral fin with a rounded tip, extending to about first anal spine. P. 12(6), 13(1). 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 not studied.

Gill rakers externally on first gill arch, 2 epibranchial, 1 in angle, 5(1), 6(6), 7(1) ceratobranchial.

Vertebrae 13+13=26(9). First caudal vertebra located between 14th and 15th anal spines. Caudal peduncle containing -1(2), -0.5(1), 0(3), 0.5(2), 1(1) vertebrae.

Color pattern in alcohol. Australoheros minuano is most similar to the A. scitulus group, from which it is distinguished by the following color pattern characters.

1.The midlateral blotch is much smaller in all developmental stages, never reaching above the dorsal half of the E2 row scales (vs. midlateral blotch optically much larger, spans from the E0 scales to the E3 scale row scales or at least into the dorsal half of the E2 row scales). When looking at the fish, in the case of A. charrua , the midlateral blotch clearly projects dorsally from the borders of the midlateral stripe, whereas it stays within the limits of the stripe in A. minuano . It is very easy to distinguish even juveniles, especially combined with points 2 and 3.

2.Develops a distinct rounded caudal base spot located above the lateral line (vs. no clearly defined caudal base spot, at most a more pigmented narrow bar at the caudal base, which is centered along the peduncle axis and does not reach the borders of the peduncle).

3.The midlateral stripe follows the axis of the body and caudal peduncle. It runs in the E0 and E1 scale rows anterior of the midlateral stripe and in scale rows E0, E1 and E2 posterior to it, i.e. the midlateral stripe gets wider posterior of the midlateral blotch (vs. a midlateral stripe also running in scale rows E0 and E1 anteriorly to the midlateral blotch, but posteriorly from the midlateral blotch turning upwards and being of the same width - i.e. the midlateral blotch is centered in the E1 scale row, while the next posterior blotch is centered in the E2 scale row and the blotch in the last body bar is centered in the E3 scale row. This successive shift in the position of the body bars one scale row up per blotch makes the midlateral stripe look like turning up dorsally posteriad from the midlateral stripe.

4.The midlateral stripe is of the same intensity all the way along the body and peduncle vs. the midlateral stripe is distinct mostly only in the area anterior from the midlateral blotch, posteriorly of it is much fainter, decomposed into the blotches as described in point 3 above.

5.Four abdominal bars (vs. three very indistinct abdominal bars).

Color in life. The life coloration and breeding in captivity of A. minuano were described by Litz et al. (2006; referred to as Cichlasoma sp. “Tacuarembó”). The coloration is similar to A. kaaygua , the ground color is also yellowish to orange, dominant males are pink or reddish, unique among Australoheros . Breeding coloration is typical for Australoheros (Ř íčan & Kullander, 2006) as described for A. kaaygua (see above). Fish attributable to A. minuano have also been pictured by Staeck (2003: p. 63 upper right) and are usually referred to as ´ Cichlasoma ´sp. ”Salto”.

Distribution. A. minuano is distributed in tributaries of the Middle and Lower Rio Uruguay in Brazil (Rio Grande do Sul) and Uruguay ( Fig. 14 ). Whether it also occurs in Argentinian tributaries is unknown. In the southern half of Uruguay and in the Atlantic drainages of Uruguay it is replaced by A. facetus . It is sympatric in distribution with A. scitulus in the northern half of its distribution area and with A. charrua . Litz et al. (2006) give a description of a locality in the Departamento Tacuarembó, Uruguay.

Etymology. The species is named after the native Minuano people, who formerly lived in the area of the Brazilian state of Rio Grande do Sul.

Notes. The difference from A. facetus , A. cf. facetus and A. guarani in coloration is subtle, with A. minuano being more similar to the A. scitulus group in having the midlateral stripe running also in the E2 scale row posteriorly from the midlateral blotch, unlike the other similar species. The midlateral stripe is also more distinctly developed. The mouth is slightly pointing down as in A. guarani , but unlike in A. facetus and A. cf. facetus , which have a slightly upturned mouth. Unlike A. guarani , the mouth of A. minuano is less sharp and more rounded and the jaws also appear proportionally shorter (see Fig. 12 ).

Additionally distinguished from A. facetus and A. guarani by a larger orbit and from A. cf. facetus and A. guarani by a smaller head width. Additionally distinguished from A. facetus and A. cf. facetus by an intermediate body depth and from A. cf. facetus also by fewer caudal peduncle vertebrae, 6 anal spines, and more anal and dorsal rays.

Additionally distinguished from A. guarani by a longer head with a shorter preorbital and interorbital distance and more L2 scales (refer to Tables 4, 5, 20 for exact values), and in the position of the caudal peduncle bar, which is in A. guarani 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. Also distinguished from A. guarani in featuring divisions of the abdominal bars in adult specimens (4 incompletely separated abdominal bars in 7 of the 9 specimens), in having more scales between the anterior insertion of the dorsal fin and the upper lateral line (3 ½ vs. 2 ½).

Despite being superficially most similar to the A. facetus -like species (i.e. A. facetus , A. guarani and A. minuano ), it has some character states resembling the A. scitulus group ( A. scitulus , A. charrua and A. kaaygua ), especially in color pattern (midlateral stripe running also in the E2 scale row posteriorly from the midlateral blotch), head shape, in having only 6 C1 gill rakers, and also by the more numerous scales between the upper lateral line and the dorsal fin. Among the A. scitulus group most similar to A. kaaygua in having 13 caudal vertebrae and 12 pectoral fin rays. Distinguished from the A. scitulus group by having 13 caudal vertebrae (vs. 14; except A. kaaygua ), 6 anal fin spines (vs. 7 or more). Additionally distinguished from A. charrua and A. scitulus by modally 24 E0 scales (vs. 25), and from A. scitulus by 16 dorsal spines (vs. 17). Some coloration characters still distinguish A. minuano from the A. scitulus group (see Color pattern in alcohol).

Distinguished from A. forquilha and A. tembe by lower meristics, especially caudal vertebrae (13 vs. 14 or more), E0 scale row count (24 vs. 25 or more), C1 gill rakers (6 vs. 7 to 8), pectoral fin rays (12 vs. 13).

Additionally distinguished from A. forquilha and A. tembe in coloration characters by having a well circumscribed midlateral stripe and a prominent caudal fin spot. A. minuano specimens also have in a much higher percentage four well abdominal bars (5 of 9 specimens—two more with not completely divided posterior bar).

Figures

FIGURE 9. Differences in squamation among Australoheros species. A, A. forquilha, B, A. sp. “ Jacui ”, C, A. tembe, D, A. kaaygua, E, A. charrua, F, A. scitulus, G, A. guarani, H, A. minuano, I, A. facetus.

FIGURE 12. Head and snout shape differences among species of Australoheros The mouth has to be completely closed in the preserved fish to observe the sometimes slight differences.

FIGURE 14. Collecting localities of Australoheros kaaygua and A. minuano (the kaaygua group). A symbol may cover more than one collecting site.

FIGURE 15. Australoheros minuano. Holotype, MCP 12710 C, 70.8 mm SL, Arroyo Canoin, Rio Uruguai drainage, Brazil.