Crenicichla ama, Říčan & Piálek & Almirón & Casciotta, 2023

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 : 42-47

Crenicichla ama sp. nov.

urn:lsid:zoobank.org:act:9C8E18CF-8833-4AAA-9395-5B2D205F1997

Figs 1A , 2 , 4A , 5–8 ; Table 1

Crenicichla sp. Piray Guazú – Piálek et al. 2012 (molecular phylogeny); 2019a (molecular phylogeny and genetic delimitation, photo of live specimen); 2019b (molecular phylogeny and genetic delimitation). — Říčan et al. 2021a (molecular phylogeny and genetic delimitation); 2021b (molecular phylogeny, genetic and morphological delimitation, photo of live specimens).

Diagnosis

Crenicichla ama sp. nov. is diagnosed from the here described sympatric C. aravera sp. nov. (and from C. yjhui , C. vittata and C. mandelburgeri ) in the main colouration pattern, chiefly composed of midlateral blotches along the body side associated with variably developed vertical bars vs composed chiefly of a dominant continuous midlateral band.

Crenicichla ama sp. nov. is distinguished from all other species of the C. mandelburgeri species complex, i.e., those with the main body colouration chiefly composed of midlateral blotches along the body side, by having small, black spots below the midlateral blotches on occasional scales in the series 0–E3 (i.e., generally between the lower lateral line and ventral border of the midlateral blotches) vs absence of such small, black spots on the flank in C. aravera sp. nov., C. hu, C. mandelburgeri , C. taikyra , C. yaha , C. yjhui , and C. ypo vs similar small dark spots however all over the flank in the Iguazú species C. iguassuensis , C. tesay , C. tuca and males of C. tapii (only on posterior part of body and caudal peduncle) vs much larger dark spots and blotches all over the flank, evidently originating from the fragmentation of the flank bars in C. gillmorlisi . Crenicichla ama is further distinguished from C. gillmorlisi in having the dots and blotches below the midlateral blotches small and sharply defined (as in the Iguazú species) vs much larger with softer borders, and in always lacking any traces of a continuous midlateral band (vs present in most juveniles and as a trace in many adults).

Crenicichla ama sp. nov. is further distinguished from all these species (except C. aravera sp. nov., C. mandelburgeri , and C. gillmorlisi ) by the colouration of the dorsal fin in breeding females which features a distinct dark white-margined blotch in the dorsal fin in C. ama (vs a long dark white-margined band in the rest).

Crenicichla ama sp. nov. is additionally distinguished from the Iguazú species C. tapii and C. tuca by having a complete series of midlateral blotches (vs only the anterior one or two blotches), and from C. tapii , C. tuca , C. tesay , C. yaha and C. taikyra by a different head and mouth morphology (lower jaw prognathous with normal lips vs lower jaw hypognathous with thick lips in C. tuca ) and by much less robust LPJ and LPJ teeth. Crenicichla ama is distinguished from the Iguazú species C. iguassuensis and C. tesay , and from C. gillmorlisi , all with the same complete series of midlateral blotches, by having the spots on body usually limited only to around the ventral borders of the midlateral blotches (vs found throughout the body including the dorsum and belly in same intensity; also in C. tuca ).

Crenicichla ama sp. nov. is most similar to C. ypo and C. hu who share the same main colouration pattern and the generalistic predatory ecomorphology (intermediate in oral jaw, LPJ jaws and teeth, and head and body proportions between all five ecomorphs of Crenicichla ) vs C. aravera sp. nov., C. yjhui , C. iguassuensis and C. mandelburgeri which are specialized piscivorous species. Crenicichla ama is thus readily distinguished from C. aravera in lower jaw length (mean 15.7%, SD 0.63 vs 16.8% of SL, SD 0.71), upper jaw length (mean 11.7%, SD 0.38 vs 12.8% of SL, SD 0.86), head depth (mean 16.9%, SD 0.70 in C. ama vs 15.8% of SL, SD 1.39), more robust LPJ and LPJ teeth, body depth (mean 23.1%, SD 1.10 vs 19.8% of SL, SD 1.09, caudal peduncle depth (mean 12.8% of SL, SD 0.37 vs 11.8% of SL, SD 0.38), and pectoral fin length (mean 22.9% of SL, SD 0.87 vs 20.6% of SL, SD 0.86).

In morphometric characters Crenicichla ama sp. nov. is distinguished from the two most similar species C. ypo and C. hu by tendency towards longer lower jaw ( C. ama 15.7% in SL, SD 0.63 vs C. ypo 14.5%, SD 2.0, vs C. hu 14.3%, SD 4.55), longer pectoral fin ( C. ama 22.8% in SL, SD 1.03 vs C. ypo 20.1%, SD 0.84, vs C. hu 19.5%, SD 5.84), and larger orbit ( C. ama 7.7% in SL, SD 0.47 vs C. ypo 6.4%, SD 0.37 vs C. hu 6.4%, SD 1.93).

Etymology

The specific epithet ‘ ama ’ is a Guaraní word for ‘rain’ and is used as a noun in apposition. The name is given in allusion to the small diagnostic spots below midlateral blotches which appear as if rain (spots) is falling from clouds (midlateral blotches).

Type material

Holotype ARGENTINA • ♂, 105.8 mm; Misiones Province , Paraná River Basin , arroyo Piray Guazú Basin, upper arroyo Piray Guazú on RP20; 26°26′34.1″ S, 54°08′29.4″ W; 18 Feb. 2012; Casciotta et al. leg.; MLP 11446 ( Fig. 1A ).

Paratypes All from Argentina, Misiones Province, Paraná River Basin, arroyo Piray Guazú Basin.

ARGENTINA – Misiones • 16 ex., 83.6–111.2 mm; same collection data as for holotype; MLP 11182 ( Fig. 2 ) • 11 ex., 67.3–103.9 mm; same collection data as for holotype; 30 Nov. 2007; Říčan et al. leg.; MLP 11180 ( Fig. 2 ) • 2 ex., 75.6–84.0 mm; same collection data as for holotype; MLP 11447 • 8 ex., 77.5–150.8 mm; Paraná River Basin, Piray Guazú River Basin, tributary to upper arroyo Piray Guazú on RP16, 23 km from San Pedro ; 26°35′45.90″ S, 54°16′59.96″ W; 26 Nov. 2016; Říčan leg.; MLP 11448 ( Fig. 2 ) .

Description

Body elongate, depth 4.0 to 4.8 times in SL (mean body depth 23.1% of SL, SD 1.10) ( Figs 1A , 2 ). Head as deep as wide or slightly deeper (mean head depth16.9% of SL, SD 0.70). Snout bluntly pointed in lateral view, 2.8 to 3.1 times in head length (mean snout length 11.4% of SL, SD 0.46). Lower jaw slightly prognathous. Tip of maxilla reaching anterior margin of orbit in most specimens. Lower lip folds widely interrupted medially. Nostrils dorsolateral. Posterior margin of preopercle serrated (27 ex.) or smooth (3 ex.). Scales on flank strongly ctenoid. Head scales cycloid. Predorsal scales small. Interopercle naked. Cheek scaled, 7 to 9 scales below eye embedded in skin. Scales in E1 row 46 (2), 47 (3), 48 (4), 49 (4), 50 (3), 51 (5), 52 (5*), 53 (2), 55 (2). Scales in transverse row 9/11 (2), 9/12 (4*), 9/13 (2), 10/11 (1), 10/12 (13), 10/13 (7), 10/14 (1). Two to three scale rows between lateral lines. Upper lateral line scales 21 (1), 22 (4), 23 (10*), 24 (9), 25 (4), 26 (2). Lower lateral line scales 8 (2), 9 (8), 10 (16), 11 (3*), 13 (1). Dorsal, anal, pectoral and pelvic fins naked. Dorsal fin XXI,9 (1); XXI,11 (12); XXI,12 (4); XXII, 9 (1); XXII,10 (1); XXII,11 (9*); XXII,12 (1); XXIII,11 (1). Anal fin III,8 (11); III,9 (18*); III,10 (1). Pectoral fin 15 (7), 16 (16*), 17 (6). Caudal-fin squamation not reaching the middle of fin. Soft-dorsal fin rounded or pointed, extending beyond caudal-fin base. Tip of anal fin not reaching caudal-fin base. Caudal fin rounded. Pectoral fin rounded, not reaching tip of pelvic fin. Microbranchiospines present on second through fourth gill arches. Gill rakers externally on first gill arch: 3 on epibranchial, 1 on angle, and 8 on ceratobranchial. Two to five patches of unicuspid teeth on fourth ceratobranchial. Lower pharyngeal tooth plate with unicuspid recurved and bicuspid crenulated curved teeth, those of posterior and medial row larger than remaining ones ( Fig. 4 ). Upper pharyngeal tooth plate with unicuspid and bicuspid teeth. Frayed zone bearing one concavity with small unicuspid teeth. Premaxillary ascending process longer than dentigerous process. Premaxilla with unicuspid teeth on outer row, larger than inner ones. Five teeth rows near symphysis. Dentary with unicuspid teeth on outer row. Premaxillary and dentary outer row teeth slightly movable, inner ones fully depressible.

Colour in life

Background colour of body grey to greenish-grey, darker on dorsum, lighter on venter. Grey preorbital stripe between anterior margin of orbit and snout tip. Postorbital stripe between posterior margin of orbit and preopercle or opercle distal margin grey. Flanks with 6 to 8 irregular black blotches between the upper and lower lateral lines, with fainter double-bar extensions above the upper lateral line up to the dorsal-fin base. Distinct black sharply defined spots below the midlateral blotches are diagnostic for the species. Suborbital stripe black, very narrow and pointed, not reaching ventral margin of cheek. Dorsal, anal, and caudal fins pale grey, males with numerous small dark scattered dots on dorsal, anal, and caudal fins, which are absent or rarely seen in females ( Fig. 2 ). Dorsal fin of breeding females with a distinctive large black blotch margined with a white ring ( Fig. 2 ). Reproductive females additionally with an orange band from pectoral-fin cleft to mid-body below the black midlateral markings. Caudal fin with a black subcircular spot, rarely bearing partial irregular pale ring, just above of midline of caudal fin.

Colour in alcohol

Similar to that of live specimens apart from lack of carotenoid pigments, most importantly concerning the orange area on flank of females. Main diagnostic characters, i.e., dark spots below midlateral blotches, and shape and configuration of suborbital stripe well visible ( Fig. 1A ) and as in live animals ( Fig. 2 ).

Distribution

Crenicichla ama sp. nov. is endemic to the arroyo Piray Guazú Basin, Paraná River Basin, Misiones Province, Argentina ( Fig. 5 ).

Habitat

Crenicichla ama sp. nov. is found throughout the Piray Guazú River Basin above the rapids separating it from the Paraná River ( Fig. 5 ). The arroyo Piray Guazú is a moderately fast flowing river. It is a clear-water basin with a predominantly bouldery stream bed and running shallow water interspersed with pools ( Figs 6–7 ). In the pools the bottom includes more silt accumulation and the pools bear macrophytes such as Echinodorus uruguayensis Arechav. and Potamogeton pseudopolygonus Hgstr.

Figures

Fig. 1. A. Crenicichla ama sp. nov., holotype, ♂ (MLP 11446, 105.8 mm). B. Crenicichla aravera sp. nov., holotype, ♂ (MLP 11450, 102.5 mm).

Fig. 2. Crenicichla ama sp. nov., live specimens. A–B. Male paratypes. C–E. Female paratypes. A. MLP 11448, tributary to upper arroyo Piray Guazú on RP16 23 km from San Pedro, 26°35′45.90″ S, 54°16′59.96″ W, November 26 2016. B. MLP 11182, 94.5 mm. C–D. MLP 11180. E. MLP 11448, tributary to upper arroyo Piray Guazú on RP16 23 km from San Pedro, 26°35′45.90″ S, 54°16′59.96″ W, November 26 2016).

Fig. 4. Lower pharyngeal tooth plate in occlusal view. A. Crenicichla ama sp. nov., paratype (MLP 11182, 94.5 mm). B. Crenicichla aravera sp. nov., paratype (MLP 11452, 93.7 mm). Scale bars = 1 mm.

Fig. 5. A.Topographic map of the Middle Paraná Basin. B. Satellite map of the Piray Guazú Basin showing distribution of the sympatric C. ama sp. nov. (dark green) and C. aravera sp. nov. (light green), and also of other species in the Iguazú (red) and the Middle Paraná (C. ypo Casciotta, Almirón, Piálek, Gómez & Říčan, 2010: dark orange; C. yjhui: orange; C. hu: yellow; C. mandelburgeri sensu lato: blue, C. gillmorlisi: grey; C. taikyra: pink). Large and small dots in the Piray Guazú Basin show localities where the species is common or rare, respectively. Dark blue and light blue dots show the northern and southern mtDNA clades of C. mandelburgeri, respectively. White bars show location of significant waterfalls. White dot (marked with X in B) shows an upstream locality in the Piray Guazú where both C. ama and C. aravera are absent. Locality 1 (in B, marked with a star) is the type locality of both new species. Localities 2 and 3 (in B) are paratype localities of the two new species. Inset in A shows the parallel species pairs in the Piray Guazú and Urugua-í basins.

Fig. 6. Type locality of C. ama sp. nov. and C. aravera sp. nov., upper arroyo Piray Guazú on RP20 (26°26′34.1″ S, 54°08′29.4″ W), 18 February 2012.

Fig. 7. Paratype locality of C. ama sp. nov., tributary to upper arroyo Piray Guazú on RP16 23 km from San Pedro (26°35′45.90″ S, 54°16′59.96″W), 26 November 2016. Crenicichla aravera sp. nov. is absent at this locality.

Fig. 8. Overview of phylogenetic relationships and molecular and morphological differentiation of C. ama sp. nov. and C. aravera sp. nov. and its parallel species pair (C. ypo Casciotta, Almirón, Piálek, Gómez & Říčan, 2010 and C. yjhui Piálek, Casciotta, Almirón & Říčan, 2019). A. Summary of phylogenetic relationships within the C. mandelburgeri species complex with a nDNA ddRAD SVDQ species tree analysis as main topology focusing on the parallel species pairs in the Piray Guazú (the two new species) and Urugua-í River basins. Species tree is based on 60% SNP-representation matrix using fixed (= homozygotic sites). Red and blue basal branches and nodes in the species tree topology show biogeography (Red: Iguazú, Blue: Middle Paraná). Numbers in parentheses are total numbers of analyzed individuals (in nDNA/ in mtDNA). Numbers at nodes show bootstrap support values. Species colours as in Fig. 5. Blue arrows show nDNA introgression from C. mandelburgeri into C. aravera and C. yjhui. Modified from Říčan et al. (2021b). B. Alternative topology to the right of the tree represents mtDNA relationships of species in the two focal species pairs. Only C. ypo does not have a mitonuclear phylogenetic conflict. Modified from Říčan et al. (2021b). C. Inference of population structure based on the Admixture analysis for the two focal species pairs. Note majority assignment of C. yjhui and C. aravera with C. ypo and C. ama and partial assignment to C. mandelburgeri sensu lato at K10 to K13, and complete separation of all species at K14. Modified from Říčan et al. (2021b). D. Morphometric variation and discrimination of the two species pairs of sympatric species from the Piray Guazú (C. ama, C. aravera) and Urugua-í (C. ypo, C. yjhui) River basins analyzed by PCA based on holotype and paratype specimens ≥ 70 mm SL. Morphological measurements followed Kullander’s (1986) methodology for Crenicichla Heckel, 1840 and were used as proportional values in % of SL. Note complete separation of species between ecomorphs (sympatric) and partial separation within ecomorphs (allopatric). Modified from Říčan et al. (2021b).