Australoheros charrua, 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 : 23-26

publication ID	https://doi.org/ 10.5281/zenodo.181173
DOI	https://doi.org/10.5281/zenodo.5669032
persistent identifier	https://treatment.plazi.org/id/6E6B0B38-AD28-0621-FF76-C6936C86FAC8
treatment provided by	Plazi
scientific name	Australoheros charrua
status	sp. nov.

Treatment

Australoheros charrua View in CoL , sp. nov.

( Fig. 11 View FIGURE 11 )

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

Holotype. MCP 13938, 77.9 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. 7 specimens, 36.2–70.5 mm SL, all from Brazil, Rio Grande do Sul, collected with the holotype. MCP 12667, 5, 36.2–69.7 mm SL; NRM 12667, 2, 61.0– 70.5 mm SL.

Diagnosis. Most similar to A. scitulus , from which it is readily distinguished in lower dorsal (16 vs. 17) and anal (7 vs. 8–9) fin spine counts, in higher dorsal ray counts (10 vs. 9), and shorter head and larger interorbital distance (refer to Table 9 for exact values). It lacks the diagnostic blotches on head and body usually present in A. scitulus .

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 View TABLE 2 .

In body form, proportions and most other features this species is very similar to A. scitulus (Ř íčan & Kullander, 2003). Mouth also small, but lower on the head with jaws of equal length. Lips narrow. Caudal peduncle considerably deeper than long (depth 30–49% of length; mean 40.5%).

Scales on head and chest not distinctly smaller than on flanks. Scales in E0 row 25(6), 26(2). Upper lateral line scales 17(6), 18(1), 19(1). Lower lateral line scales 7(1), 8(3), 9(3), 10 (1). Scales between upper lateral line and dorsal fin: 4 large anteriorly (or 3 large and one small), 2 large and one small posteriorly. Cheek scale rows 3(3), 4(5). About 8 scale rows between the opercular flap and the anterior insertion of the pelvic fin (as in A. scitulus ).

Dorsal fin with one basal scale row, starting from the seventh or eighth spine and running posteriad; interradial scales appear from 14th or 15th spine membrane, in single rows. Two or three last interradial membranes without scales. Anal fin with one basal scale row; interradial scales in single rows, starting between penultimate spine membrane and first ray membrane. Caudal fin densely scaled, scales ctenoid; interradial scales in single rows; hind margin of scaly area concave, extending to between one-third and middle of caudal fin.

Soft dorsal fin pointed, extending to middle or three quarters of caudal fin. D. XVI,9 (1), XVI,10 (4), XVII,9 (1), XVII,10 (2). Soft anal fin pointed, of about the same length as dorsal fin. A. VII,7 (2), VII,8 (5), VIII,7 (1). Anal fin pterygiophores 12(4), 13(4). Pelvic fin extending to second or third anal spine. Pectoral fin with third and fourth rays longest, extending to about the level of anus and just to the midlateral blotch. P. 12(1), 13(7) Caudal fin rounded to subtruncate.

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(5), 7(2) ceratobranchial.

Vertebrae 13+13=26(1), 13+14=27(6), 14+14=28(1). Caudal peduncle containing 2(1), 0(3), 0.5(2), 1(2) vertebrae.

Color pattern in alcohol. Basic coloration markings include six flank bars, i.e. three abdominal bars. The caudal spot bar is very narrow, with only a very small or completely missing caudal spot. The caudal peduncle bar is due to the very short caudal peduncle confluent with the darker caudal spot bar. Juvenile and subadult specimens do have a clearly developed caudal base spot above the lateral line. Vertical bars are relatively wide, faint, indistinct in their ventral parts. Other general aspects of the coloration are given above in the comparison of coloration patterns of A. charrua , A. scitulus and A. kaaygua . The arrangement of the bars on the body is essentially the same as described in A. scitulus (Ř íčan & Kullander, 2003). Slight differences are found in the midlateral stripe. Compared to A. scitulus , the midlateral stripe is even better developed and more continuous anteriorly from the midlateral blotch. Posterior from the midlateral blotch, the stripe is better described as a series of two blotches, the anterior one being centered in the E2 scale row, the posterior one in the E3 scale row.

Unpaired fins without spots. Flank and head scales also without spots.

Color in life. No photographs of live specimens are known to us. Live fish probably look very similar to a fish photographed by Staeck (2003: p. 63 upper left). This photograph shows A. scitulus of the form referred to as `C.`sp. ”Quarai” ( Lucena & Kullander, 1992), where some northern populations do not distinctly develop the A. scitulus apomorphic spotting patterns, but are still distinguishable as A. scitulus using meristic characters and some coloration characters as the posterior part of the midlateral stripe and mouth/head shape.

Distribution. Known only from the type locality in Brazil, Rio Grande do Sul, Río Uruguay drainage ( Fig. 2 View FIGURE 2 ), overlapping in distribution with A. minuano ( Fig. 14 View FIGURE 14 ). Also Crenicichla gaucho has the same limited area of distribution.

Etymology. The species is named after the indigenous people of the Charrua , which inhabited an area including the Rio Grande do Sul State ( Brazil).

charrua facetus

Obrit diameter in head length 36.8±1.5 30.3±2.4 Ceratobranchial 1 gill rakers 6.1±0.6 7.9±0.7 Anal fin spines 7.1±0.3 6.1±0.3 Head length 32.4±1.0 34.5±1.5 caudal vertebrae 13.9±0.4 13.2±0.4 Snout length in head length 26.3±2.0 30.6± 3.1 E 0 scales 25.3±0.5 24.5±0.6 Pectoral fin rays 12.9±0.4 13.5±0.7 Body depth 46.9±1.5 49.1±2.1 Notes. Australoheros charrua is most similar to A. scitulus and also A. kaaygua (see phylogenetic analyses) in general appearance, body shape (relatively deep-bodied), small isognathous snout, few C1 gill rakers (6), short caudal peduncle and coloration. Similarities in coloration (in preserved specimens) to A. scitulus and A. kaaygua include a dominant longitudinal stripe and a prominent midlateral blotch and are described in more detail below. In general, A. charrua is more similar to A. scitulus , both in higher meristic counts, details of coloration patterns and head shape (mouth positioned low on head with the anterior upper margin of premaxilla well below the horizontal from the ventral margin of the eye). The mouth is positioned even lower on the head in A. charrua than in A. scitulus making the straight ventral outline of the head aligned even more horizontally; Fig. 12 View FIGURE 12 ). A. kaaygua on the other hand has similarities with A. scitulus in being spotted on unpaired fins and flank scales, but it can be easily distinguished from both, A. scitulus and A. charrua , in meristic counts. Both, A. charrua and A. kaaygua , lack spots on the operculum, suboperculum and posterior part of head, diagnostic for A. scitulus .

The similarities in coloration between A. scitulus , A. charrua , and the below described A. kaaygua include the following:

1.The midlateral stripe is more distinctly developed anterior from the midlateral blotch than posterior from it in adult specimens.

2.The midlateral stripe turns upwards posterior from the midlateral spot, whereas it follows the body axis in all the other species (except A. minuano , see below; i.e. it goes all the way along the body in scale rows E0 and E1). This bending is most pronounced in A. charrua where 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. In A. kaaygua and A. scitulus the blotch posterior to the midlateral blotch is centered in the same scale row as the midlateral blotch (i.e. E1 scale row), and only the last blotch is very high on the body. However, all three share the feature that the midlateral stripe does not continue in the E0 scale row posterior to the midlateral blotch (which is also shared with A. minuano ).

3.The midlateral blotch is very large, spanning from the E0 scales to the E3 scale row scales or at least into the dorsal half of the E2 row scales

4.There is no clearly visible caudal base spot, mostly only a more pigmented narrow bar at the caudal base, which is fused with the caudal peduncle bar.

5.All species develop always only three abdominal bars and there are also no traces of four developing bars in developmental series.

Additionally distinguished from A. kaaygua by having more vertebrae (14 vs. 13), more E0 scales (25 vs. 24), more cheek scale rows (3–4 vs. 3) and pectoral fin rays (13 vs. 12), and in being less deep-bodied and with a shorter snout (see A. charrua ).

charrua cf. facetus Head length 32.4±1.0 35.8±1.0 caudal vertebrae 13.9±0.4 13.1±0.3 Preorbital distance in head length 22.6±3.2 16.0±2.5 Caudal peduncle vertebrae 0.1±0.9 1.16±0.4 Caudal peduncle depth 40.2±6.5 48.1±3.5 Ceratobranchial 1 gill rakers 6.1±0.6 7.5±0.5

E0 scales 25.3±0.5 24.4±0.6 Interorbital width in head length 35.3±2.6 31.1±2.5 Body depth 46.9±1.5 44.5±1.5 Pectoral fin length 30.3± 1.4 28.7± 1.0 Except for the coloration characters, distinguished from the A. facetus -like species also by a different head shape, with the mouth very low on the head, small terminal isognathous mouth and except A. guarani also in having only three (indistinct) abdominal bars (vs. 4). Additionally distinguished from all in having more caudal vertebrae (14 vs. 13) and more E0 scales (25 vs. 24), from all except A. minuano in having 6 C1 gill rakers (vs. 7–8), and from all except A. cf. facetus in having 7 anal spines (vs. 6). For all meristic and morphometric differences between A. charrua and the A. facetus -like species see Tables 10–13.

Also distinguished from A. forquilha and A. tembe by having fewer caudal peduncle vertebrae (none, or up to one vs. modally 2), and 7 anal fin spines (vs. 6 in A. forquilha and A. tembe ). From A. forquilha additionally by 6 C1 gill rakers (vs. 8).