Crenicichla aravera, 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 : 47-53

Crenicichla aravera sp. nov.

urn:lsid:zoobank.org:act:1B66C894-3DE8-4439-8431-7F6D9EE41790

Figs 1B , 3 , 4B , 5–8 ; Table 2

Crenicichla sp. Piray Guazú line – 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 aravera sp. nov. is diagnosed by a rare main colouration pattern (shared only with C. yjhui and to some extent with C. mandelburgeri within the C. mandelburgeri species complex, plus with C. vittata ) which features a dominant continuous midlateral band vs the most common main colouration pattern composed of midlateral blotches along the body, present in all other species of the complex including C. ama sp. nov.

Crenicichla aravera sp. nov. is readily distinguished from C. vittata by 50–55 scales in E1 row (vs 78– 85) and also by colouration, where the midlateral band in C. vittata (and in C. mandelburgeri ) is not always present, e.g., in breeding or stressed individuals (vs always present and the dominant colouration pattern in C. aravera ).

Crenicichla aravera sp. nov. can also be distinguished from the most similar C. yjhui in having less scales in E1 row (50–55 vs 53–64) and in transverse row (9/12–12/10 vs 10/13–11/16). Crenicichla aravera is further distinguished from C. yjhui in one colouration-pattern character in adult breeding females, which have a distinct dark white-margined blotch in the dorsal fin (shared with C. ama sp. nov. vs a long dark white-margined band in C. yjhui ). Crenicichla aravera can further be marginally distinguished from C. yjhui in the better degree of development of all of the piscivory-associated characters, i.e., in statistically longer snout (12.1% of SL, SD 1.04 vs 11.4%, SD 0.43), longer head (33.1%, SD 0.90 vs 31.9%, SD 0.78), longer lower (16.8%, SD 0.71 vs 15.9%, SD 0.50) and upper jaws (12.8%, SD 0.86 vs 12.5%, SD 0.61), longer caudal peduncle (15.4%, SD 0.69 vs 13.6%, SD 0.76), and also in several other characters, i.e., in statistically deeper head (15.8%, SD 1.39 vs 15.1%, SD 0.64), longer pectoral fin (20.6%, SD 0.85 vs 19.5%, SD 0.98), larger eye (7.2%, SD 0.49 vs 6.8%, SD 0.47).

Crenicichla aravera sp. nov. is further diagnosed by its specialized piscivorous ecomorphology characterized by long oral jaws (mean lower jaw length 16.8% of SL, SD 0.71; mean upper jaw length 12.8% of SL, SD 0.86), shallow head (mean head depth 15.8% of SL, SD 1.39), delicate LPJs and LPJ teeth, streamlined bodies (mean body depth 19.8% of SL, SD 1.09) which it shares with C. yjhui , C. iguassuensis , C. mandelburgeri and with C. tuca (in oral jaws and head length) within the C. mandelburgeri species complex plus with C. vittata vs species with other ecomorphologies ( C. ama sp. nov., C. gillmorlisi , C. ypo , C. hu, C. taikyra , C. tesay , C. yaha , C. tapii and C. tuca [in head depth and body depth]) with shorter oral jaws (mean lower jaw length 11.0–15.7% of SL; mean upper jaw length 9.1–11.7% of SL), deeper heads (mean head depth 16.0–18.2% of SL), more robust LPJs and LPJ teeth, and less streamlined and deeper bodies (mean body depth 22.0–24.9% of SL). Crenicichla aravera is further diagnosed from C. ama by caudal peduncle shape (mean depth 11.8% of SL, SD 0.38 vs 12.8% of SL, SD 0.37) and by pectoral fin length (mean 20.6% of SL, SD 0.86 vs 22.9% of SL, SD 0.87).

Etymology

The specific epithet ‘ aravera ’ is a Guaraní word for ‘flash’ (as associated with stormy and rainy weather) and is used as a noun in apposition. The name is given in association with its sister-species C. ama sp. nov. (meaning rain) in allusion to the long body, pointed head, and a dominant colouration marking of a black midlateral band and rapid hunting strategy, all alluding to a flash.

Type material

Holotype ARGENTINA • ♂, 102.5 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; 30 Nov. 2007; Říčan et al. leg.; MLP 11450 ( Figs 1B , 3 ).

Paratypes

All from Argentina, Misiones Province, Paraná River Basin, arroyo Piray Guazú Basin, same locality as holotype.

ARGENTINA – Misiones • 2 ex., 81.2–83.3 mm; same collection data as for holotype; MLP 11451 ( Fig. 3 ) • 4 ex., 2 (C&S), 90.1–135.3 mm; 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 11452 ( Fig. 3 ) .

Non-type material

ARGENTINA • 12 ex., 2 (C&S), 79.9–101 mm; Misiones Province , Paraná River Basin , arroyo Piray Guazú Basin , lower arroyo Piray Guazú at Balneario Piray Guazú; 26°29′1.66″ S, 54°35′11.98″ W; 23 Feb. 2012; Casciotta et al. leg.; MLP 11453 .

Description

Body elongate, depth 4.6 to 5.3 times in SL (mean body depth 19.8% of SL, SD 1.09) ( Figs 1B , 3 ). Head as deep as wide or slightly deeper (mean head depth 15.8% of SL, SD 1.39). Snout bluntly pointed in lateral view, 2.5 to 3.0 times in head length (mean snout length 12.1% of SL, SD 1.04). Lower jaw slightly prognathous. Tip of maxilla reaching anterior margin of orbit in specimens over 80.0 mm SL. Lower lip folds widely separated along symphysis. Nostrils dorsolateral. Posterior margin of preopercle serrated. Scales on flank strongly ctenoid. Head scales cycloid. Predorsal and prepelvic scales small. Interopercle naked. Cheek scaled, 8 to 11 scales below eye embedded in skin. Scales in E1 row 50 (1), 51 (1), 52 (1), 53 (1), 55 (3). Scales in transverse row 9/12 (2), 9/13 (1), 10/13 (1), 10/14 (1*), 12/10 (1). Two to three scale rows between lateral lines. Upper lateral line scales 21 (1), 23 (1), 25 (3), 26 (2*). Lower lateral line scales 8 (1), 10 (3*), 11 (2), 12 (1). Dorsal, anal, pectoral and pelvic fins naked. Dorsal fin XX,12 (1); XXI,11 (2); XXI,12 (2*); XXII,11 (1); XXIII,11 (1). Anal fin III,8 (4); III,9 (3*). Pectoral fin 16 (4); 17 (3*). Caudal-fin squamation not reaching the middle of fin. Soft-dorsal fin rounded or pointed, surpassing caudal-fin base. Tip of anal fin reaching or not 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. Three to five patches of unicuspid teeth on fourth ceratobranchial. Lower pharyngeal tooth plate with unicuspid recurved and bicuspid crenulated curved anteriorly 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 one. 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 yellowish-grey, darker on dorsum, lighter on venter, where almost white. Deep grey preorbital stripe between anterior margin of orbit and snout tip. Postorbital stripe between posterior margin of orbit and preopercle or opercle distal margin deep grey to black. Deep grey to black midlateral band along entire body as dominant colouration patter and main diagnostic character on body. Light grey hints of vertical bars only visible on dorsum above midlateral band. Suborbital stripe black, rather wide, not distinctly pointed, and short, not reaching ventral margin of cheek. Dorsal, anal, and caudal fins pale grey, males with numerous rather large dark scattered dots on dorsal, anal, and caudal fins, which are absent or rarely seen in females ( Fig. 3 ). Dorsal fin of breeding females with distinctive large black blotch ( Fig. 3 ). Females additionally with more yellow tones below midlateral band, in reproductive females likely more intensified into an orange band from pectoral-fin cleft to mid-body. Caudal fin with a black subcircular spot, rarely bearing a 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 of orange area on flank of females. Main diagnostic characters, i.e., black continuous midlateral band with spotshaped irregularities on ventral margin, and shape and configuration of suborbital stripe well preserved ( Fig. 1B ) and as in live animals ( Fig. 3 ).

Distribution

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

Habitat

Crenicichla aravera sp. nov. is only found in the Piray Guazú Basin above the rapids separating it from the Paraná River, but has so far only been collected from the main river channel ( Fig. 5 ), unlike C. ama sp. nov., which is also known from tributaries. Crenicichla aravera is syntopic with C. ama . Other details concerning the arroyo Piray Gauzú as given for C. ama .

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. 3. Crenicichla aravera sp. nov., live specimens. A. Holotype, ♂ (MLP 11450). B. Paratype, ♂ subadult (MLP 11451, 81.2 mm). C–D. Female paratypes (MLP 11451, 83.3 mm; MLP 11452, 93.7 mm), upper arroyo Piray Guazú on RP20, February 18 2012.

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).