Crenicichla, Heckel, 1840

Říčan, Oldřich, Piálek, Lubomír, Almirón, Adriana & Casciotta, Jorge, 2023, Description of two new species forming a sympatric species pair of Crenicichla (Teleostei: Cichlidae) endemic to the Piray Guazú River in the Paraná River Basin, Misiones, Argentina and belonging to the C. mandelburgeri species complex, European Journal of Taxonomy 879, pp. 38-63 : 53-57

Keys to the species of Crenicichla from the Middle Rio Paraná Basin (the Crenicichla mandelburgeri species group plus C. vittata )

Because of the taxonomical and morphological complexity of the C. mandelburgeri species complex we have chosen to provide two determination keys, each primarily based on a different main character. We believe this may facilitate determination of some species.

The first key is more suited to the present study as it is based on the main colouration patterns, which also distinguish the two newly described species.

The second key is more generally suited to the C. mandelburgeri species complex and the existing literature on parallel evolution of ecomorphologies in Crenicichla since it is based on oral jaw characteristics (the main charaters involved in the formation and parallel evolution of ecomorphs).

For the keys we have chosen to use only readily visible external characters. Many of the characters used in the key will work only for adult specimens (at least 70 mm SL), especially the colour and colouration pattern characters. The main colouration pattern of the species is scored based on preserved specimens where there is less variation than in live specimens, while the colouration of the dorsal fin in females is best visible in live specimens.

Key to the species of Crenicichla from the Middle Rio Paraná Basin (the Crenicichla mandelburgeri species group plus C. vittata ) based on the main colouration pattern

1. Main colouration pattern of adults chiefly or most often composed of a dominant continuous midlateral band, in the latter case sometimes in combination with vertical bars ............................. 2

– Main colouration pattern of adults chiefly composed of midlateral blotches along the body side without any continuous midlateral band ........................................................................................... 5

– Main colouration pattern chiefly composed of paired vertical bars in young, and fragmented into dark blotches and spots all over the sides including side of belly in adults, midlateral band when present is continuous, endemic to the Acaray tributary, endemic to Paraguay................................... ............................................................................................ C. gillmorlisi Kullander & Lucena, 2013

2. The midlateral band is always present as a dominant colouration pattern in all growth stages, moods and under other conditions, scales in E1 row 50–64 ........................................................................ 3

– Depending on growth stage, mood and other factors the dominant body colouration can change from a midlateral band to vertical bars, or be a combination of the two, scales in E1 row either 42–57 or 78–85 ................................................................................................................................................ 4

3. Breeding females with a distinct dark white-margined blotch in the dorsal fin, scales in E1 row 50–55, endemic to the Piray Guazú tributary, endemic to Argentina................... C. aravera sp. nov.

– Breeding females with a distinct dark white-margined long band in the dorsal fin, scales in E1 row 53–64, endemic to the Urugua-í tributary, endemic to Argentina...................................................... ............................................................................. C. yjhui Piálek, Casciotta, Almirón & Říčan, 2019

4. Midlateral band when present always fully continuous, with barely discernible fluctuation in width, scales in E1 row 78–85, widespread in the Lower Paraná and entire Paraguay Basin, also present in Lower Uruguay and lower portions of the Middle Paraná in Paraguay, Brazil, Argentina and Uruguay......................................................................................................... C. vittata Heckel, 1840

– Midlateral band often semicontinuous or even distrupted (i.e., always of clearly fluctuating width), vertical bars when present always as clear double-bars, scales in E1 row 42–57, endemic to Middle Paraná main River and some non-isolated tributaries in Paraguay and Argentina............................. ...................................................................................................... C. mandelburgeri Kullander, 2009

5. Breeding females with a distinct dark white-margined blotch in the dorsal fin, scattered spots on body below the midlateral band in both sexes, especially in males, endemic to the Piray Guazú tributary, endemic to Argentina................................................................................. C. ama sp. nov.

– Breeding females with a distinct dark white-margined long band in the dorsal fin ......................... 6

6. Scattered spots on body below the midlateral band in both sexes, especially in males, endemic to the Iguazú, Argentina and Brazil............................................................................................................ 7

– Without spots on body below the midlateral band in both sexes, endemic to Middle Paraná Basin apart from the Iguazú ...................................................................................................................... 10

7. Oral jaws prognathous (i.e., lower jaw projecting in front of upper jaw), mouth large, corner of mouth reaching well below eye ....................................................... C. iguassuensis Haseman, 1911

– Oral jaws isognathous or hypognathous (i.e., upper jaw projecting in front of lower jaw) ............. 8

8. Mouth large, corner of mouth reaching below vertical from anterior margin of eye, lips very thick and bulbous .......................................... C. tuca Piálek, Dragová, Casciotta, Almirón & Říčan, 2015

– Mouth small, not reaching eye, lips normal ..................................................................................... 9

9. Well-developed vertical double-bars (only species in the Iguazú with this character), anterior one or two midlateral blotches much more dominant over the remaining, which are usually only visible as connections between the double bars, a well-formed (not decomposed into spots) narrow suborbital stripe inclined significantly posteriad, near absence of dark scattered dots on flanks in males and complete absence in females ............... C. tapii Piálek, Dragová, Casciotta, Almirón & Říčan, 2015

– Vertical bars and less developed double bars only visible above midlateral line, anterior four or more midlateral blotches well dominant, suborbital stripe decomposed into spots, wider, and less inclined posteriad, both sexes with dark scattered dots on flanks ........... C. tesay Casciotta & Almirón, 2008

10. Oral jaws prognathous (i.e., lower jaw projecting in front of upper jaw), mouth rather large (i.e., corner of mouth reaching below vertical from anterior margin of eye) ..........................................11

– Oral jaws isognathous or hypognathous (i.e., upper jaw projecting in front of lower jaw), mouth rather small (i.e., not reaching eyes) ............................................................................................... 12

11. Anterior two to three midlateral blotches dominant, background colouration light grey, midlateral blotches distinctly H-like with dorsally continuing double bars, females with a wide wide orange to red stripe along the entire length of the basal portion of the dorsal fin above which is found a shorter black band margined in white, suborbital stripe of normal length and width, composed of spots, which do not form horizontal lines, endemic to the Urugua-í tributary, endemic to Argentina......... .................................................................. C. ypo Casciotta, Almirón, Piálek, Gómez & Říčan, 2010

– All midlateral blotches well developed, background colouration very dark grey to blackish, midlateral blotches square-like with dorsally continuing single wide bars, females only with the shorter black band margined in white in the dorsal fin without the orange to red band, suborbital stripe short and wide, ventrally widest, composed of spots which do form horizontal lines, endemic to the Piray Miní tributary, endemic to Argentina.............................. C. hu Piálek, Říčan, Casciotta & Almirón, 2010

12. Anterior two to three midlateral blotches usually more dominant, midlateral blotches distinctly H-like with dorsally continuing double bars, suborbital stripe shorter and wider, composed of spots which tend to form horizontal lines, scales in E1 row 48–51 (mean 50), endemic to the Urugua-í tributary, endemic to Argentina.................................... C. yaha Casciotta, Almirón & Gómez, 2006

– All midlateral blotches equally developed, midlateral blotches square-like with dorsally continuing single wide bars, suborbital stripe of normal length and width, composed of spots which tend to form horizontal lines, scales in E1 row 54–60 (mean 56–57), endemic to the lower portion of the Middle Paraná and some non-isolated tributaries in Paraguay and Argentina................................................ ............................................. C. taikyra Casciotta, Almirón, Aichino, Gómez, Piálek & Říčan, 2013

Key to the species of Crenicichla from the Middle Rio Paraná Basin (the Crenicichla mandelburgeri species group plus C. vittata ) based on oral jaw characteristics

1. Oral jaws isognathous or hypognathous (i.e., upper jaw projecting in front of lower jaw), mouth generally rather small to small (i.e., not reaching eyes), except in one species where quite large ... 2

– Oral jaws prognathous (i.e., lower jaw projecting in front of upper jaw), mouth rather large to large (i.e., corner of mouth reaching below vertical from anterior margin of eye) ................................... 6

2. Mouth large, corner of mouth reaching below vertical from anterior margin of eye, lips very thick and bulbous .......................................... C. tuca Piálek, Dragová, Casciotta, Almirón & Říčan, 2015

– Mouth small, not reaching eye, lips normal ..................................................................................... 3

3. Scattered spots on body below the midlateral band in both sexes, especially in males (except for one species where weakly developed), endemic to the Iguazú, Argentina and Brazil............................ 4

– Without spots on body below the midlateral band in both sexes, endemic to Middle Paraná Basin apart from the Iguazú ........................................................................................................................ 5

4. Well-developed vertical double-bars (only species in the Iguazú with this character), anterior one or two midlateral blotches much more dominant over the remaining, which are usually only visible as connections between the double bars, a well-formed (not decomposed into spots) narrow suborbital stripe inclined significantly posteriad, near absence of dark scattered dots on flanks in males and complete absence in females ............... C. tapii Piálek, Dragová, Casciotta, Almirón & Říčan, 2015

– Vertical bars and less developed double bars only visible above midlateral line, anterior four or more midlateral blotches well dominant, suborbital stripe decomposed into spots, wider, and less inclined posteriad, both sexes with dark scattered dots on flanks ........... C. tesay Casciotta & Almirón, 2008

5. Anterior two to three midlateral blotches usually more dominant, midlateral blotches distinctly H-like with dorsally continuing double bars, suborbital stripe shorter and wider, composed of spots which tend to form horizontal lines, scales in E1 row 48–51 (mean 50), endemic to the Urugua-í tributary, endemic to Argentina.................................... C. yaha Casciotta, Almirón & Gómez, 2006

– All midlateral blotches equally developed, midlateral blotches square-like with dorsally continuing single wide bars, suborbital stripe of normal length and width, composed of spots which tend to form horizontal lines, scales in E1 row 54–60 (mean 56–57), endemic to the lower portion of the Middle Paraná and some non-isolated tributaries in Paraguay and Argentina................................................ ............................................. C. taikyra Casciotta, Almirón, Aichino, Gómez, Piálek & Říčan, 2013

6. Main colouration pattern of adults chiefly or most often composed of a dominant continuous midlateral band, in the latter case sometimes in combination with vertical bars ............................. 7

– Main colouration pattern of adults chiefly composed of midlateral blotches along the body side without any continuous midlateral band ..........................................................................................11

– Main colouration pattern chiefly composed of paired vertical bars in young, and fragmented into dark blotches and spots all over the sides including side of belly in adults, midlateral band when present is continuous, endemic to the Acaray tributary, endemic to Paraguay................................... ............................................................................................ C. gillmorlisi Kullander & Lucena, 2013

7. The midlateral band is always present as a dominant colouration pattern in all growth stages, moods and under other conditions, scales in E1 row 50–64 ........................................................................ 8

– Depending on growth stage, mood and other factors the dominant body colouration can change from a midlateral band to vertical bars, or be a combination of the two, scales in E1 row either 42–57 or 78–85 ................................................................................................................................................ 9

8. Breeding females with a distinct dark white-margined blotch in the dorsal fin, scales in E1 row 50–55, endemic to the Piray Guazú tributary, endemic to Argentina................... C. aravera sp. nov.

– Breeding females with a distinct dark white-margined long band in the dorsal fin, scales in E1 row 53–64, endemic to the Urugua-í tributary, endemic to Argentina...................................................... ............................................................................. C. yjhui Piálek, Casciotta, Almirón & Říčan, 2019

9. Midlateral band when present always fully continuous, with barely discernible fluctuation in width, scales in E1 row 78–85, widespread in the Lower Paraná and entire Paraguay Basin, also present in Lower Uruguay and lower portions of the Middle Paraná in Paraguay, Brazil, Argentina and Uruguay......................................................................................................... C. vittata Heckel, 1840

– Midlateral band most often semicontinuous or even distrupted (i.e., always of clearly fluctuating width), vertical bars when present always as clear double-bars, scales in E1 row 42–57, endemic to Middle Paraná main River and some non-isolated tributaries in Paraguay and Argentina................ ...................................................................................................... C. mandelburgeri Kullander, 2009

10. Breeding females with a distinct dark white-margined blotch in the dorsal fin, a few scattered spots on body below the midlateral band in both sexes, especially in males, endemic to the Piray Guazú tributary, endemic to Argentina................................................................................. C. ama sp. nov.

– Breeding females with a distinct dark white-margined long band in the dorsal fin ........................11

11. Scattered spots on body below the midlateral band in both sexes, especially in males, endemic to the Iguazú, Argentina and Brazil........................................................... C. iguassuensis Haseman, 1911

– Without spots on body below the midlateral band in both sexes, endemic to Middle Paraná Basin apart from the Iguazú, endemic to Argentina................................................................................. 12

12. Anterior two to three midlateral blotches dominant, background colouration light grey, midlateral blotches distinctly H-like with dorsally continuing double bars, females with a wide wide orange to red stripe along the entire length of the basal portion of the dorsal fin above which is found a shorter black band margined in white, suborbital stripe of normal length and width, composed of spots, which do not form horizontal lines, endemic to the Urugua-í tributary, endemic to Argentina......... .................................................................. C. ypo Casciotta, Almirón, Piálek, Gómez & Říčan, 2010

– All midlateral blotches well developed, backgroundcolouration very dark grey to blackish, midlateral blotches square-like with dorsally continuing single wide bars, females only with the shorter black band margined in white in the dorsal fin without the orange to red band, suborbital stripe short and wide, ventrally widest, composed of spots which do form horizontal lines, endemic to the Piray Miní tributary, endemic to Argentina.............................. C. hu Piálek, Říčan, Casciotta & Almirón, 2010