Australoheros forquilha, 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 : 14-23

Australoheros forquilha , sp. nov.

( Fig. 4 )

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

Holotype. MCP 13936, male, 110.4 mm SL, Brazil, Rio Grande do Sul. Rio Forquilha , Rio Uruguai drainage, road from Maximiliano de Almeida to Machadinho. 4 October 1988. E. Pereira, L. Bergmann, P. Azevedo, and A. Ramírez.

Paratypes. 18 specimens, 15.6–129.7 mm SL. Brazil, Rio Grande do Sul: MCP 12123, 1, 42.1 mm SL, Rio Forquilha , Rio Uruguai drainage, road from Maximiliano de Almeida to Machadinho, 6 km from Maximiliano de Almeida, 25 May 1988. E. P. Lerner; MCP 13389, 1, 15.6 mm SL, Rio Forquilha , Rio Uruguai drainage, road from Maximiliano de Almeida to Machadinho. 27 February 1989. E. Pereira, L. Bergmann, P. Azevedo, and A. Ramírez; NRM 13389, 1, 92.3 mm SL, Rio Forquilha , Rio Uruguai drainage, road from Maximiliano de Almeida to Machadinho. 27 February 1989. E. Pereira, L. Bergmann, P. Azevedo, and A. Ramírez; MCP 12525, 1, 107.4 mm SL, collected with the holotype; MCP 6262, 9/35, C, D, N, P, Q, R, T, U, V, S, Sanga das Aguas Frias, Rio Uruguai drainage, Irai. 1985. L. R. Malabarba, R. E. Reis, and S. B. Malman. Brazil, Santa Catarina: MCP 12777, 1, 85.2 mm SL, Rio Canoas, Rio Uruguai drainage, road from Tupitinga to Celso Ramos. 10 November 1988. C. Lucena, E. Pereira, and P. Azevedo; MCP 18743, 4, 61.4–129.7 mm SL, Rio Rancho Grande where crossing road BR-153 to Piritiba, Rio Uruguai drainage, 11 January 1996.

E. Filho, V. Schulz, S. Meurer, and P. Iaczinski.

Additional non-type material: 21 specimens, Argentina, Misiones: ZSM 23482, 15/16, A, B, C, D (C&S), E, F, G, H, I, J, K, L, M, N, O, 65.8–99.5 mm SL, Río Soberbio, Río Uruguay drainage, Soberbio. 1966. J. Foerster; ZSM 23060, 6/12, D (C&S), I, J, L, C, G, 47.1–77.0 mm SL, Rio Soberbio, Río Uruguay drainage, Soberbio. 1966. J. Foerster. Fractions denote numbers of specimens in mixed lots including more than one species.

Diagnosis. Australoheros forquilha is unique among all Australoheros species in having dark markings below the orbit along the postero-lateral border of the suborbital series ( Fig. 5 B, C), in having checkerboardspotted dorsal, anal and caudal fins and in having more than 14 caudal vertebrae in some specimens, in having 25–26 E0 scales (vs. 24–25), a downward pointing subterminal mouth (all other Australoheros species), and in having the shortest interorbital and longest preorbital distances ( Figs. 6 and 7 ). Also distinguished from all species in the unique scale cover of the base of dorsal fin with two cover scales corresponding to one transverse scale row.

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 .

Australoheros forquilha is similar to A. tembe in having a more slender body with a narrower interorbital region of the head, shorter pectoral and ventral fins and a long caudal peduncle including two or more vertebrae, in having slightly thickened lips and a proportionally large mouth. It is hypothesized to have affinities with A. tembe (see results).

The head profile is more round than in the other species and the mouth is subterminal. Lachrymal bone deeper than wide. Lips comparatively thick. Caudal peduncle considerably deeper than long (depth 45–70% of length; mean 56%).

Scales on chest about half the size than the biggest scales in the E0 row above the pectoral fin (thus smaller than in A. facetus with the largest chest scales). About 8 scale rows between the opercular flap and the anterior insertion of the pelvic fin in the holotype. Scales in E0 row 24(1), 25(16), 26(11). Upper lateral line scales 16(1), 17(10), 18(12), 19 (4). Lower lateral line scales 8(6), 9(17), 10(4), 11(1). Scales between upper lateral line and dorsal fin scale cover 3 posteriorly, 4 plus two small parallel scales anteriorly, forming a sheath of smaller scales arranged in pairs per scale row, along the insertion of the dorsal fin ( Fig. 8 A, 9A). Scales between lateral lines 2. Cheek scale rows 3 (1), 4(15), 5(4). Interradial scales appear from 15th (rarely 14th) 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, from the 6th membrane (i.e. between the last spine and the first branched ray), lacking on two last interradial membranes. Caudal fin densely scaled, scales ctenoid; interradial scales in single rows; posterior margin of scaly area concave, extending to between one-third and middle of caudal fin.

Soft dorsal fin pointed, extending to the middle of the caudal fin (up to the end of caudal fin in the holotype). D. XV, 10 (2), XV, 11 (4), XVI, 9 (3), XVI, 10 (16), XVI, 11 (6). Soft anal fin pointed, of about the same length as dorsal fin. A. V,8 (1), VI, 7 (12), VI, 8 (15), VI, 9 (1), VII, 8 (2). Anal fin pterygiophores 11 (13), 12 (16), 13 (2). Pelvic fin base slightly posterior of pectoral fin base; first ray longest. Pelvic fin comparatively short, not extending to the genital papilla in most specimens (reaching to the first anal spine in the holotype). Pectoral fin comparatively short, with a rounded tip, posteriorly reaching to the same level as the pelvic fin. P. 13(19), 14(9). Caudal fin with rounded corners, subtruncate with a smooth indentation due to slightly shorter midline rays.

All teeth caniniform, slightly curved. Outer row teeth increasing in size symphysiad, upper jaw anterior teeth longest and more robust, lower jaw anterior teeth subequal, midline two pairs more robust.

Lower pharyngeal tooth plate in a dissected specimen about one quarter wider than long (length 75% of width) and very shallow compared to other Australoheros species ( Fig. 10 ; cf. Fig. 17 and fig. 2 in Ř íčan & Kullander, 2006). Dentigerous area wider than long. 8–9 teeth along midline, 26 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 projecting anteriorly from shelf.

Gill rakers externally on first gill arch: 2 epibranchial, 1 in angle, 7(7), 8 (15), 9 (4) ceratobranchial.

Vertebrae 13+13=26(1), 13+14=27(23), 13+15=28(6), 14+13=27(1). Caudal peduncle contains 1.5(6), 2(13), 2.5(6), 3(6) vertebrae.

Color pattern in alcohol. Six or seven vertical flank bars, a midlateral blotch in the third flank bar from posterior, an inconspicuous caudal fin base spot and the caudal peduncle bar make up the principal markings. Vertical bars are relatively wide, faint, indistinct in their ventral parts. The posteriormost bar bears the caudal spot, which is very faint or even absent in some specimens. The caudal peduncle bar covers the posterior less than half of the peduncle. The third bar, being the first flank bar, runs between the ends of dorsal and anal fins. The third flank bar, bearing the midlateral blotch is centered above the anteriormost portion of the anal fin. There are three or four abdominal bars. The number varies in adults, whereas all juveniles have four bars: compared to the situation in A. scitulus , the bar anterior from the midlateral blotch bar is divided into two. The last flank bar runs from anterior of the dorsal fin insertion, along the posterodorsal edge of the opercular cleft down to the insertion of the pectoral fin or slightly anterior from it.

There are only weak traces of a midlateral stripe in adult specimens. Dorsal, anal and caudal fins with dark spots in a checker-board spotting pattern on interradial membranes. A line of black longitudinal blotches below the orbit along the postero-lateral border of the suborbital series.

Color in life. Only one photograph of a life A. forquilha is known to us and it was presented in the Appendix to Stawikowski and Werner (2004: p. 455) as “ Cichlasoma ” cf. tembe . The fish in the photograph clearly shows characters distinctive for A. forquilha (checkerboard spotting on unpaired fins, opalescent markings on head and also on body scales, head shape with a low position of mouth). It was collected in an unspecified tributary of the Upper Uruguay in Brazil, and it thus also in distribution agrees with A. forquilha . The specimen is photographed in a field aquarium and is very colorful, with a red lower portion of body and head and green scales on body. The green color is similar to A. tembe .

Distribution. Australoheros forquilha is endemic to the tributaries of the Upper Uruguay in Brazil and its southernmost locality is in the Río Soberbio, an Argentinian tributary of the Middle Río Uruguay just below the Moconá falls separating the Middle and Upper Rio Uruguay ( Fig. 3 ). It shares its distribution with A. kaaygua in the Río Uruguay basin ( Fig. 14 ).

Etymology. The species is named after the Rio Forquilha , Rio Grande do Sul, Brazil, from where the species is described.

Notes. Australoheros forquilha can be easily distinguished from A. tembe by the diagnostic coloration markings lacking altogether in A. tembe (see above), a subterminal mouth and a more rounded head profile, 10 or 11 dorsal fin rays (vs. 9 in A. tembe ), 8 anal fin rays (vs. 7), and also by the mentioned shorter preorbital and interorbital distance and a shorter caudal peduncle (including 2 vs. 3 vertebrae; modal values) (see Table 8).

Distinguished from the A. scitulus group ( A. scitulus , A. charrua ) and A. kaaygua by body shape (being more elongated with shorter pectoral and ventral fins), larger mouth, higher C1 gill raker counts (7–8 vs. 6), longer caudal peduncle (modally containing 2–3 vertebrae vs. 1 or none) and coloration. It lacks the longitudinal stripe dominant in these three species and also has the bar in front of the midlateral blotch (in about half of the adult specimens and all juveniles) divided into two bars contrary to a single bar present in both juveniles and adults of the three latter species.

Distinguished additionally from A. scitulus (and juvenile A. kaaygua ) in lacking any dominant rows of spots on flank scales (above anterior part of upper lateral line), in lacking the opercular and head spots of A. scitulus , also no prominent black spot in the axil of pectoral fin. Also distinguished from A. scitulus by having 16 dorsal fin spines (vs. 17), 6 to 7 anal fin spines (vs. 8–9), and narrower interorbital distance (23.3–35.3% HL, mean 27.6% vs. 29.7–40.0%, mean 35.2% in specimens above 50mm SL).

Additionally distinguished from both A. kaaygua and A. charrua in having spotted unpaired fins, 6 anal fin spines (vs. 7), 4–5 cheek scale rows (vs. 3), and narrower interorbital distance (23.3–35.3% HL, mean 27.6% vs. 31.7–38.5%, mean 35.5% vs. 34.5–37.7%, mean 36.2% in specimens above 50mm SL). Additionally distinguished from A. kaaygua in having 14–15 caudal vertebrae (vs. 13) and 13–14 pectoral fin rays (vs. 12–13).

In addition, distinguished from the A. facetus group ( A. facetus , A. cf. facetus and A. minuano ) and A. guarani by higher meristics, especially caudal vertebrae (14 to 15 vs. 13), caudal peduncle vertebrae (more than 2 vs. fewer than 2), E0 scale row count (25 or more vs. 24), and from A. minuano additionally by fewer C1 gill rakers (7 to 8 vs. 6) and pectoral fin rays (13 vs.12).

Additionally distinguished from the A. facetus group species in mouth shape and position (inferior mouth vs. slightly up-turned mouth in A. facetus and A. cf. facetus , terminal in A. minuano ), in coloration by not having a well-circumscribed midlateral stripe and a prominent caudal fin spot. The A. facetus group species also have a much higher percentage of four well-developed abdominal bars.

forquilha tembe

Caudal peduncle depth 57.2±4.8 67.7±4.8 Caudal peduncle vertebrae 2.16±0.5 3.04±0.2) Dorsal fin rays 10.2±0.6 9.0±0.0 Ventral fin length 28.7±2.6 26.1±1.6 Interorbital width in head length 27.6±2.9 30.2±1.5 Preorbital distance in head length 25.0±3.5 22.1±3.1 The material from Soberbio (Misiones, Argentina) is in bad condition. This excludes most coloration characters, including the diagnostic suborbital markings and the checkerboard-spotting of unpaired fins from being studied. Soberbio specimens have slightly lower counts of caudal vertebrae (13–14 vs. 14–15), slightly less caudal peduncle vertebrae (modally 2 vs. modally 3), 5–6 anal fin spines (vs. 6–7), slightly lower total dorsal fin counts (25–26 vs. 26–27), 25 vs. 26 E0 scales and 3–4 vs. 4–5 cheek scale rows. Soberbio populations possess the diagnostic shortest interorbital and longest preorbital distances. The inclusion of the Soberbio populations into A. forquilha is in agreement with the RDA analysis (Ř íčan & Kullander, 2006), but in conflict with the populations as terminal taxa phylogenetic analyses (which include all informative characters including the above mentioned proportions; op. cit.). Untill better-preserved specimens from the area are studied, or until a phylogeographic study sheds more light on the matter, we prefer to treat the Soberbio population as A. forquilha .

scitulus charrua Dorsal fin spines 16.9±0.4 16.3±0.5 Head length 34.6±1.4 32.4±1.0 Anal fin spines 8.5±0.5 7.1±0.3 Dorsal fin rays 9.0±0.6 9.8± 0.5 E 0 scales 24.9±0.5 25.3±0.5 Interorbital width in head length 32.1±3.2 35.3±2.6

Figures

FIGURE 3. Collecting localities of Australoheros forquilha and A. tembe (the forquilha group). A symbol may cover more than one collecting site.

FIGURE 4. Australoheros forquilha. Holotype, MCP 13936, male, 110.4 mm SL, Rio Forquilha, Rio Uruguai drainage, Brazil.

FIGURE 5. Diagnostic head markings of A. scitulus (A) and A. forquilha (B, C).

FIGURE 6. Interorbital distance plotted against standard length, showing clear separation of A. forquilha from the remaining species.

FIGURE 7. Preorbital distance plotted against standard length, showing clear separation of A. forquilha from the remaining species.

FIGURE 8. Differences in squamation among Australoheros species, showing two extreme situations. A, A. forquilha, B, A. facetus. Note the shorter basal scale row at the base of the dorsal fin, less scaled dorsal and anal fins, and less scale rows between the upper lateral line and the dorsal fin (both anteriorly and posteriorly) in A. facetus.

FIGURE 10. Lower pharyngeal jaw of a dissected specimen of Australoheros cf. forquilha, ZSM 23060 G, in (top to bottom) occlusal, caudal and left lateral aspect.

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

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