Australoheros angiru, Říčan, Oldřich, Piálek, Lubomír, Almirón, Adriana & Casciotta, Jorge, 2011

Říčan, Oldřich, Piálek, Lubomír, Almirón, Adriana & Casciotta, Jorge, 2011, Two new species of Australoheros (Teleostei: Cichlidae), with notes on diversity of the genus and biogeography of the Río de la Plata basin, Zootaxa 2982, pp. 1-26 : 15-18

Australoheros angiru sp. nov.

( Figs 7 , 8 , 9 ).

“ Cichlasoma ” facetum— Staeck 1998a: 62 –63; 1998b: 81–85 “ Cichlasoma ” sp. Iguaçu — Staeck 2003: 64 –65

“ Cichlasoma ” sp. Iguaçu — Stawikowski and Werner 2004: 455 Australoheros sp. jacutinga — Říčan and Kullander 2006: 6 Australoheros kaaygua— Říčan and Kullander 2008: 28 (in part)

Holotype. MCP 13937, 73.2 mm SL, Brazil, Santa Catarina State, rio Uruguai drainage, rio Jacutinga, road BR 283 from Ceará to Concordia, col: Bergmann et al., October 1988.

Paratypes. 13 specimens, 24.6–77.0 mm SL, all from Brazil. Santa Catarina State, rio Uruguai drainage: MCP 13383, 6 ex., 24.6–77.0 mm SL, rio Jacutinga, road BR 283 from Ceará to Concordia, col: Reis et al., February 1989. MCP 12509, 1 ex., 75.0 mm SL, same data as holotype. MCP 13011, 6 ex., 44.2–61.4 mm SL, rio Jacutinga, road BR 283 from Ceará to Concordia, col: Reis et al., December 1988.

Additional non-type material. Paraná State, rio Iguaçu drainage: NUP 3913, 2 ex., rio São Pedro, tributary to rio Iguaçu, Pinhão county, 26º05´S, 51º45'W, col: Nupélia staff, March 1993. NUP 3914, 1 ex, rio Iratim (Linígrafo), tributary to rio Iguaçu, Palmas county, boundary with Pìnhão-PR, 26º05´S, 51º45´W, col: Nupélia staff, April 1993. NUP 3915, 1 ex, rio São Pedro, tributary to rio Iguaçu, Pinhão county, 26º05´S, 51º45'W, col: Nupélia staff, March 1993. Rio Grande do Sul State, rio Uruguai drainage: MCP 46328, 13 ex., Sanga das Aguas Frias, Irai, col: Malabarba et al., 1985. Argentina, Misiones province, río Uruguay drainage: ZSM 23482a, 1 ex., P, río Soberbio, El Soberbio, col: J. Foerster, 1966. ZSM 23060a, 4 ex., río Soberbio, El Soberbio, col: J. Foerster, 1966. ZSM 23060c, 2 ex. (C&S), río Soberbio, El Soberbio, col: J. Foerster, 1966.

Diagnosis. Australoheros angiru is one of the most deep-bodied species of Australoheros (body depth in SL>49%; shared with A. guarani and A. facetus ). It has been previously associated with A. kaaygua , but it is the sister species of A. minuano based on DNA characters.

Australoheros angiru is distinguished from A. kaaygua by having less scale rows between anterior end of dorsal fin and upper lateral line (ch4 states 1–2 vs. 0), by a very narrow or missing caudal base spot, by a pure yellow ground color (vs. yellowish-green), by yellow eyes (vs. dark green), by more scales between anterior end of dorsal fin and upper lateral line (5 vs. 4), more anal fin spines (7 vs. 6), more anal fin rays (> 7 vs. <7), more dorsal fin rays (9 vs. 8), less E0 scales (24 vs.> 25), more L1 scales (> 17–18 vs. 16), less L2 scales (8 vs.> 9), and by a being more deep-bodied (49.6% vs. 43.8% SL), and having a shorter caudal peduncle (7.4% vs. 10.4% SL).

Australoheros angiru is distinguished from A. minuano by a large and dominant midlateral blotch, very narrow or missing caudal base spot, by lacking a pinkish body coloration, by a small terminal or subterminal mouth (vs. large supraterminal), by more scales between the anterior end of the dorsal fin and the upper lateral line (5 vs. 4), less anal fin rays (7 vs. 8), less dorsal fin rays (9 vs. 10), and by slight differences in body depth (49.6% vs. 46.9% SL) and in preorbital distance (7.3% vs. 6.0% SL).

For distinguishing characters to all other Australoheros species see the Notes section.

Description. Based on specimens over 60 mm SL, with notes on smaller specimens. Meristic data are summarized in Table 2, morphometric data are summarized in Table 3.

Comparatively deep bodied (mean body depth 49.6% SL). Snout short, straight in lateral view. Jaws isognathous. Mouth small.

Scales on head and chest not distinctly smaller than on flanks. Scales in E0 row 23(3), 24(16*), 25(4). Upper lateral line scales 16(1), 17(6*), 18(8). Lower lateral line scales 7(4), 8(7*), 9(4). Scales between upper lateral line and dorsal fin 4 anteriorly, 1 large plus 1 small posteriorly. Cheek scale rows 3(14*), 4(2). About 8 scale rows between the opercular flap and the anterior insertion of the pelvic fin. Dorsal fin with one basal scale row, starting from the 7th or 8th spine and running posteriad; interradial scales appear from 14th or 15th spine membrane, in single rows. Anal fin with one basal scale row; interradial scales in single rows, from penultimate spine. 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 beyond middle of caudal fin. D. XVI,9(16*), XVI,10(13), XVII,8(2). Soft anal fin pointed, of about the same length as dorsal fin. A. VI,7(2), VI,8(3), VII,7(17*), VII,8(8), VIII,6(1). Anal fin pterygiophores 11(2), 12(22*), 13(7). First pelvic fin ray longest, extending up to the second anal fin spine. Pectoral fin with a rounded tip, third and fourth rays longest, extending just to the midlateral blotch. P. 12(11*), 13(5). 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. Number of lower jaw teeth up to 16 in one outer hemiseries, upper jaw tooth row much shorter, with about 7 or 8 teeth in one outer hemiseries. Lower pharyngeal tooth plate not studied. Gill rakers externally on first gill arch, 2 epibranchial, 1 in angle, 5(4), 6(11*), 7(1) ceratobranchial.

Vertebrae 13+13=26(29*), 13+14=27(2). Caudal peduncle with no vertebrae (10) or containing 0.5(4), 1(14*), 1.5(1) vertebrae.

Color pattern in alcohol. Six to seven vertical flank bars, a caudal peduncle bar confluent with the caudalbase bar, and a midlateral stripe bearing the midlateral blotch in the fourth flank bar (sensu Říčan et al. 2005) make up the principal markings. All fins and body are without conspicuous spots or blotches. The midlateral stripe is more distinct anteriorly from the midlateral blotch than posteriorly, and the midlateral blotch itself is a dominant coloration pattern element. Vertical bars are relatively wide, faint, indistinct in their ventral parts. The midlateral stripe posteriorly from the midlateral blotch does not align with the lower lateral line and aligns with the E1 scale row and does not continue in the E0 scale row. Posteriorly from the midlateral blotch, the stripe is slightly decomposed into two blotches in the respective vertical flank bars. The blotch posterior from the midlateral blotch is centered in the same scale row as the midlateral blotch (i.e. E1 scale row), whereas the second blotch is more elongate along the vertical axis and centered in the E2 scale row, making the impression that the midlateral stripe makes a dorsally directed turn at its posterior end. The arrangement of the bars on the body in essentially the same as described for A. scitulus ( Říčan & Kullander 2003) . Very small spots present on the bases of some body scales in adult specimens. In juveniles the spotted pattern of the body is much more pronounced, with virtually every scale on the body having a spot at its base, including those in the anterior part of the E4 scale row (i.e. as in adult A. scitulus ).

Life coloration. Coloration of life specimens from the rio Uruguai drainage is unknown to us. Staeck (1998a, 1998b, 2003: p. 64) photographed specimens from the rio Iguaçu drainage ( Fig. 7 ). These specimens have a yellow ground coloration with dark vertical bars and a dark horizontal stripe. Several other species of Australoheros have a yellowish ground color, but it is best developed in A. angiru . The iris is also yellow. The caudal fin has red dorsal and ventral margins and corners. This character is not unique for A. angiru , and can also be seen in A. kaaygua and in populations of A. facetus from the state of Uruguay. Breeding animals have the typical Australoheros breeding coloration with the horizontal interruption of the black vertical bars in their dorsal portion between the opercle and the midlateral blotch ( Říčan & Kullander 2003; Staeck 1998a: p. 82, 1998b: p. 62, 2003: p. 65). Females in breeding coloration develop a black blotch in the dorsal fin. Staeck (1998b, 2003) describes behavior and spawning under aquarium conditions.

Distribution. Australoheros angiru has a disjunct distribution in the rio Iguaçu and in the upper rio Uruguai. One locality is so far known from the middle río Uruguay in Misiones province, Argentina ( Fig. 10 ).

Etymology. The Guaraní word angirû means friend, partner (amigo or compañero in Spanish). The etymology is based on the fact that A. angiru and A. kaaygua have been confused as one species ( Říčan & Kullander 2008). New data have however demonstrate that they are two non-sister group species living in the same river drainage (río Iguazú), though not sympatrically.

Notes. Part of Australoheros angiru material (MCP 6262) has been previously considered conspecific with A. kaaygua ( Říčan & Kullander 2008) . The authors were aware of the morphological variation within A. kaaygua (sensu Říčan & Kullander 2008), but lack of DNA data and of first hand examination of the type series of A. kaaygua made them sceptical about describing a new species with an additionally unusual distribution (occuring in the same river basin, río Iguazú as A. kaaygua , but not in sympatry, and at the same time also in the río Uruguay). DNA data from the rio Iguaçu populations in Brazil ( A. angiru ) however show no relationship to A. kaaygua in the río Iguazú in Argentina ( Fig. 2 ). DNA data from the río Uruguay are so far lacking. A more detailed morphological analysis ( Fig. 1 ) also supports the notion of two unrelated species, with populations of A. angiru from both the rio Iguaçu and from the río Uruguay forming a homogenous clade with short intraspecific branch lengths. The sister species of A. angiru is A. minuano , while that of A. kaaygua is A. tembe ( Fig. 3 ).

The MCP 6262 lot additionally included two species ( Říčan and Kullander, 2008). Nine specimens from this lot are paratypes of Australoheros forquilha Říčan and Kullander, 2008 . Thirteen specimens from this lot represent A. angiru (previously erroneously treated as A. kaaygua in Říčan and Kullander, 2008) and were separated into a new lot MCP 46328.

Additional diagnostic characters of Australoheros angiru that separate it from all other species except A. kaaygua and A. minuano are as follows. It is distinguished (in decreasing order of overall similarity; except for species from coastal drainages treated as last) from A. charrua and A. scitulus by having less scale rows between posterior end of upper lateral line and dorsal fin (ch3 state 2 vs. 0 vs. 1), less caudal vertebrae (13 vs. 14), in being more deep-bodied (50 vs. 45% SL), and in having less E0 scales (24 vs.>25). Additionally distinguished from A. charrua by details in the shape of the midlatral stripe (see description) and by lacking a pinkish body coloration. Additionally distinguished from A. scitulus by lacking black blotches on the opercular series, having less anal fin spines (7 vs. 8), less dorsal fin spines (16 vs. 17), less caudal vertebrae (13 vs. 14), in being more deep-bodied (50 vs. 45% SL), and in having less pectoral fin rays (12–13 vs. 13–14).

Australoheros angiru is distinguished from A. tembe by having less scale rows between anterior end of dorsal fin and upper lateral line (ch4 states 1–2 vs. 0), by a very narrow or missing caudal base spot, a shorter dorsal fin scale cover (ch1 state 1 vs. 0), less scale rows between the posterior end of the upper lateral line and dorsal fin (ch3 state 2 vs. 0), by lacking thick lips, by having more anal fin spines (7 vs. 6), less caudal vertebrae (13 vs. 14), and less caudal peduncle vertebrae (0 vs. 3). It is distinguished from A. guarani , A. facetus , A. acaroides and A. taura by a large and dominant midlateral blotch (except A. facetus ), very narrow or missing caudal base spot, and details in the shape of the midlatral stripe (see description).

Australoheros angiru is additionally distinguished from A. guarani by a small terminal or subterminal mouth (vs. large supraterminal), more anal fin spines (7 vs. 6), shorter preorbital distance (21 vs. 25% HL), and less C1 gill rakers (6 vs. 7). Additionally distinguished from A. facetus by a longer dorsal fin scale cover (ch1 state 1 vs. 2), more anal fin spines (7 vs. 6), less anal fin rays (7 vs. 8), less pectoral fin rays (12–13 vs. 13–14), and less C1 gill rakers (6 vs. 7–8). It is additionally distinguished from A. acaroides by a longer dorsal fin scale cover (ch1 state 1 vs. 2), shorter caudal peduncle (40% CPD vs. 50–60% CPD), by being more deep-bodied (50 vs. 45% SL), and having a narrower interorbital distance (35 vs. 40–45% HL). It is distinguished from A. taura by also lacking a pinkish body coloration, by a small terminal or subterminal mouth (vs. large supraterminal), shorter caudal peduncle (40% CPD vs. 50% CPD), by being more deep-bodied (50 vs. 40% SL), by a narrower interorbital distance (35 vs. 40% HL), less pectoral fin rays (12–13 vs. 13–14), and less E0 scales (24 vs.>25).

Australoheros angiru is distinguished from A. ykeregua and A. forquilha by a shorter dorsal fin scale cover (ch1 state 1 vs. 0), a different scale pattern along anterior border of dorsal fin (ch2 state 0 vs. 1), less scale rows between posterior end of upper lateral line and dorsal fin (ch3 state 2 vs. 0), very narrow or missing caudal base spot, absence of opalescent spots below orbit, unpaired fins without checker-board spotted pattern, absence of red colored lower head area and opercular membrane, by a small terminal or subterminal mouth (vs. large supraterminal), less dorsal fin rays (9 vs. 10), less caudal peduncle vertebrae (0 vs. 2 vs. 2.5), shorter caudal peduncle (40% CPD vs. 60% CPD), by being more deep-bodied (50 vs. 45 vs. 40% SL), with a wider head (55 vs. <50% HL), and in having less pectoral fin rays (12–13 vs. 13–14). Additionally distinguished from A. ykeregua by a large and dominant midlateral blotch, and more anal fin spines (7 vs. 6). Additionally distinguished from A. forquilha by less scale rows between anterior end of dorsal fin and upper lateral line (ch4 state 1 vs. 0), absence of opalescent scale rows on body, and less pectoral fin rays (12–13 vs. 13–14).

Australoheros angiru is distinguished from all the Atlantic coast species north of A. acaroides and A. taura ( A. autrani , A. barbosae , A. capixaba , A. ipatinguensis , A. macacuensis , A. macaensis , A. muriae , A. paraibae , A. ribeirae , A. robustus , A. saquarema ) by a longer dorsal fin scale cover (ch1 state 1 vs. 2), a large and dominant midlateral blotch, details in the shape of the midlatral stripe (see description), shorter caudal peduncle (40% CPD vs.>50% CPD), in being more deep-bodied (50 vs. 45% SL), with a narrower interorbital distance (35 vs. 40% HL), less pectoral fin rays (12–13 vs. 13–14), and less E0 scales (24 vs.>25).

Figures

FIGURE 1. Tree-based delimitation using MP phylogenetic analysis of morphological data. The tree shown is one of two MP trees (L = 693; N = 2; CI = 0.51; RI = 0.66), which differ only in the internal topology of A. angiru. Branch lengths represent morphological divergences.

FIGURE 2. Molecular phylogeny of the Río de la Plata basin Australoheros species using BI. Node support values shown for MP / BI analyses. The alternative dotted topology represents neighbor-joining (NJ) analysis. Asterisk denotes posterior probability of 1.00.

FIGURE 3. Combined MP morphological-molecular phylogeny with between-state scaling internal weighting between morphological and molecular data (L = 2457; N = 1; CI = 0.58; RI = 0.49). Node support values show MP bootstrap for two types of analyses (left: between-state scaling internal weighting structure / right: all characters weighted equally).

FIGURE 7. Color plate. Horizontaly from upper left to lower right. Australoheros forquilha, rio Forquilha, rio Uruguai drainage, Rio Grande do Sul, Brazil (not preserved). Australoheros ykeregua (MACN-ict 9467, holotype), río Uruguay drainage, arroyo Paraiso (or Canal Muerto), Misiones province, Argentina. Australoheros kaaygua (MACN-ict 9473), río Iguazú drainage, small stream 7 km SW from Andresito, Misiones province, Argentina. Australoheros angiru, male in neutral colors, rio Chopim, rio Iguaçu drainage, Paraná, Brazil (not preserved). A. angiru, male and female in breeding colors guarding fry, same locality (not preserved). All A. angiru photographs courtesy of Wolfgang Staeck.

FIGURE 8. Australoheros angiru. Holotype, MCP 13937, 73.2 mm SL, rio Jacutinga, rio Uruguai drainage, Brazil.

FIGURE 9. Australoheros angiru. Paratype, MCP 13011, 48.1 mm SL, rio Jacutinga, rio Uruguai drainage, Brazil.

FIGURE 10. Map of the middle Río de la Plata basin. Distributions of the two new species (A. angiru and A. ykeregua) and their relatives, as well as five areas of endemism are shown. Percent values and corresponding arrows demonstrate sequence divergences in the cyt b gene (see Fig. 2) between the species and areas of endemism in the río Iguazú and río Uruguay river drainages (plus the arroyo Urugua – í). Divergence of A. ykeregua from its sister species A. forquilha is 2.3 %. This divergence probably represents the minimum age of the Salto Moconá. Divergence of A. kaaygua from its sister species A. tembe is 3.8 %, and of A. angiru from A. tembe is similarly 3.6 – 3.7 %. This probably represents the age of the division of the arroyo Urugua – í from the río Iguazú. Divergence of A. angiru from its sister species A. minuano is 4.2 %. This is likely a divergence of the rio Iguaçu and río Uruguay drainages. Divergence of A. angiru from A. kaaygua (4.8 %), two unrelated species endemic to the río Iguazú river drainage, demonstrates an old divergence within the Iguazú drainage basin itself. See Discussion for more detailed description of the biogeography.