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Fig. 3 in Water temperature affects aggressive interactions in a Neotropical cichlid fish

Fig. 3. Mean ± SE of initial (third day) and final (eighth day) frequencies of a. restrained aggression and b. overt aggression of group-housed fish. Different letters show differences among treatments. Mixed Model ANOVA completed by Fisher-LSD post hoc test.

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Fig. 1 in Temperature affects the hypoxia tolerance of neotropical Cichlid Geophagus brasiliensis

Fig. 1. Malate Dehydrogenase enzyme activity of Geophagus brasiliensis exposed to normoxic (90% oxygen saturation) and hypoxia (20% oxygen saturation) conditions for 8 hours at 20°C, 24°C and 28°C. a. in liver; b. in white muscle; and c. in heart. Asterisks indicates significant differences between treatments at the same temperature, p <0.05. Different lowercase letters indicate significant differences for the same treatment at the temperatures studied, p <0.05.

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Fig. 3 in Temperature affects the hypoxia tolerance of neotropical Cichlid Geophagus brasiliensis

Fig. 3. Citrate Synthase enzyme activity of Geophagus brasiliensis exposed to normoxic (90% oxygen saturation) and hypoxic (20% oxygen saturation) conditions for 8 hours at 20°C, 24°C and 28°C. a. in liver; b. in white muscle; and c. in heart. Asterisks indicates significant differences between treatments at the same temperature, p <0.05. Different lowercase letters indicate significant differences for the same treatment at the temperatures studied, p <0.05.

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Relaxed feeding constraints facilitate the evolution of mouthbrooding in Neotropical cichlids

<p>Multifunctionality is often framed as a core constraint of phenotypic evolution. Mouthbrooding, a form of parental care where offspring develop inside a parent's mouth, increases multifunctionality by adding a major function (reproduction) to a structure already serving other vital functions (feeding and respiration). Despite increasing multifunctionality, mouthbrooding has evolved repeatedly from other forms of parental care in at least 7 fish families. We hypothesized that mouthbrooding is more likely to evolve in lineages with feeding adaptations that are already advantageous for mouthbrooding. We tested this hypothesis in Neotropical cichlids, where mouthbrooding has evolved 4–5 times, largely within winnowing clades, providing several pairwise comparisons between substrate brooding and mouthbrooding sister taxa. We found that the mouthbrooding transition rate was 15 times higher in winnowing than in non-winnowing clades, and that mouthbrooders and winnowers overlapped substantially in their buccal cavity morphologies, which is where offspring are incubated. Species that exhibit one or both of these behaviors had larger, more curved buccal cavities, while species that exhibit neither behavior had narrow, cylindrical buccal cavities. Given the results we present here, we propose a new model for the evolution of mouthbrooding, integrating the roles of multifunctional morphology and the environment.</p>

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Fig. 2 in Relationships between morphology, diet and spatial distribution: testing the effects of intra and interspecific morphological variations on the patterns of resource use in two Neotropical Cichlids

Fig. 2. Head of Satanoperca pappaterra (a) and Crenicichla britskii (b), showing differences in the mouth protrusion.

Fig. 8 in Reproductive cycle of the Neotropical cichlid yellow peacock bass Cichla kelberi: A novel pattern of testicular development

Fig. 8. Testicular morphological characteristics of the Regression phase in C. kelberi. (a) Testicular proximal region, highlighting the big volume of melano-macrophage centers (mmc). (b) Gonad in restructuration with details to the Sertoli cells phagocytizing (Sp) the residual sperm (rSz), and the apoptotic cells (double arrow). (c) Transversal section along the testis in Regression. (d) Testicular periphery (dorsal region) highlighting the intense proliferation of primary spermatogonia in this region (Sg). primary spermatogonial cluster (dotted line); I - interstitial tissue; Sp - Sertoli cell in phagocytosis; Sc1 - primary spermatocysts; Sg1 - primary spermatogonia; Sg2 - secondary spermatogonia. H.E. stain.

Fig. 7 in Reproductive cycle of the Neotropical cichlid yellow peacock bass Cichla kelberi: A novel pattern of testicular development

Fig. 7. Testicular morphological characteristics of Late GE Development phase in C. kelberi. (a) Longitudinal section of the main testicular duct (dt). (b) Germinal epithelium discontinuity in the distal region of the testicular lobules (asterisk). (c) Spermatogenic cysts in different development phases, highlighting the spermatocytes cyst in metaphase (mt) of the first meiotic division. (d) Discontinuity of the germinal epithelium along the testicle. H.E. stain. Egd - discontinuous germinal epithelium; mmc - melano-macrophage centers; S - Sertoli cell; Sc1 - primary spermatocysts; Sg1 -primary spermatogonia; Sg2 - secondary spermatogonia cysts; St - spermatids cysts; Sz - sperm. H.E. stain.

Fig. 6 in Reproductive cycle of the Neotropical cichlid yellow peacock bass Cichla kelberi: A novel pattern of testicular development

Fig. 6. Testicular morphological characteristics of Mid GE Development phase in C. kelberi. (a and b) Testicular anastomosing region, highlighting the beginning of the germinal epithelium discontinuity (asterisk), in both the anastomosing region and lobules near the main testicular ducts. (c) Discontinuous germinal epithelium, with cysts in different development stages and lots of sperm (Sz) in the lobular lumen. (d) Peripheral lobular region (dorsal) highlighting the continuous germinal epithelium and clusters of primary spermatogonia (dotted line). ar - anastomosing region; dt - main testicular ducts; I - interstice; m - basal membrane; mt - metaphase; S - Sertoli cell; Sc1 - primary spermatocysts; Sg1 - primary spermatogonia; Sg2 - secondary spermatogonia; St - spermatids; ta - tunica albuginea; cytoplasmic extension (hollow arrow). H.E. stain.

Fig. 5 in Reproductive cycle of the Neotropical cichlid yellow peacock bass Cichla kelberi: A novel pattern of testicular development

Fig. 5. Testicular morphological characteristics of Early GE Development phase in C. kelberi. (a) Main testicular duct region (dt), highlighting the narrow light (arrow). (b) Testicular lobules with continuous germinal epithelium (Egc) and germ cells cysts in different phases of spermatogenesis. (c) Germ cells cysts in different phases of spermatogenesis. (d) Distal lobular region, highlighting the germ cells clusters (dotted line). Bv - blood vessels; S - Sertoli cell; Sc1 - primary spermatocysts; Sg1 - primary spermatogonia; Sg2 - secondary spermatogonia; St - spermatids; ta - tunica albuginea. H. E. stain.

Fig. 1 in Reproductive cycle of the Neotropical cichlid yellow peacock bass Cichla kelberi: A novel pattern of testicular development

Fig. 1. Testicular structure of C. kelberi in transversal section. (a) Testis draft highlighting the different regions. (b) A lobule representation, highlighting the cystic type spermatogenesis and the unrestricted distribution of spermatogonia. (c) Testis ventral region, showing the main testicular duct (dt), anastomosing region (ar) and the beginning of the lobular region (L). Reticulin reaction. (d) Testis dorsal region, highlighting the blind end (double arrow) of the testicular lobules, which are formed by the connective tissue septa sent by tunica albuginea (ta). Reticulin reaction. c - spermatogonial clusters; I - interstice; S - Sertoli cell; Sc - spermatocyte; Sg - spermatogonia; St - spermatid.

Fig. 3 in Reproductive cycle of the Neotropical cichlid yellow peacock bass Cichla kelberi: A novel pattern of testicular development

Fig. 3. Structure of the germinal epithelium in C. kelberi. (a and b) germinal epithelium highlighting the spermatogenic cysts in distinct layers. H.E. stain. (c) Outline highlighting the maintenance of a continuous germinal epithelium after the higher layers cysts break. Sc1 - primary spermatocyte; St - spermatid; Sz - spermatozoa.

Fig. 4 in Reproductive cycle of the Neotropical cichlid yellow peacock bass Cichla kelberi: A novel pattern of testicular development

Fig. 4. Testicular morphological characteristics of the initial phases of C. kelberi gonadal development. (a) and (b) Immature phase: germinal epithelium showing a reduced number of primary spermatogonia (Sg1). (c) and (d) Preparatory phase: presence of lots of primary spermatogonia and cysts of secondary spermatogonia (Sg2). Mitotic figures are also observed in this phase, highlighting the spermatogonial proliferation (arrow).

Fig. 6 in Descriptions of five new species of the Neotropical cichlid genus Gymnogeophagus Miranda Ribeiro, 1918 (Teleostei: Cichliformes) from the rio Uruguay drainage

Fig. 6. Lower pharyngeal tooth plates in occlusal view: a, G. pseudolabiatus, MCP 11228, 71.6 mm SL; b, G. mekinos, MCP 11251, 84.2 mm SL; c, G. constellatus, MCP 10827, 91.4 mm SL; d, G. missioneiro, MCP 12725, 59.3 mm SL; e, G. lipokarenos, MCP 12991, 89 mm SL. Scale bars = 1 mm.

Fig. 5 in Descriptions of five new species of the Neotropical cichlid genus Gymnogeophagus Miranda Ribeiro, 1918 (Teleostei: Cichliformes) from the rio Uruguay drainage

Fig. 5. Gymnogeophagus pseudolabiatus: top, paratype, male, UFRGS 7754, 102.0 mm SL, arroyo Cuaró Grande on Ruta 4, tributary of rio Quaraí, Artigas, Uruguay; bottom, paratype, female, UFRGS 7754, 80.5 mm SL, arroyo Cuaró Grande on Ruta 4, tributary of rio Quaraí, Artigas, Uruguay.

Fig. 2 in Descriptions of five new species of the Neotropical cichlid genus Gymnogeophagus Miranda Ribeiro, 1918 (Teleostei: Cichliformes) from the rio Uruguay drainage

Fig. 2. Gymnogeophagus gymnogenys: top, male, UFRGS 17259, 120 mm SL, lagoa Corvina, Mostardas; Rio Grande do Sul, Brazil; bottom, female, uncatalogued, 84 mm SL, Saco da Alemoa, delta do rio Jacuí, Porto Alegre, Rio Grande do Sul, Brazil.

Fig. 7 in Descriptions of five new species of the Neotropical cichlid genus Gymnogeophagus Miranda Ribeiro, 1918 (Teleostei: Cichliformes) from the rio Uruguay drainage

Fig. 7. Rio Sarandi III, on the road from Santana do Livramento to Quaraí, Santana do Livramento, Rio Grande do Sul, Brazil, type locality of Gymnogeophagus pseudolabiatus.

Fig. 10 in Descriptions of five new species of the Neotropical cichlid genus Gymnogeophagus Miranda Ribeiro, 1918 (Teleostei: Cichliformes) from the rio Uruguay drainage

Fig. 10. Gymnogeophagus missioneiro: top, holotype, male, MCP 23495, 109.3 mm SL, arroio Ximbocuzinho, on the road from São Luiz Gonzaga to Bossoroca, 4 km from São Luiz Gonzaga, Rio Grande do Sul, Brazil; middle, paratype, female, MCP 12725, 72.8 mm SL, arroio Passo do Rosário or Passo da Cancela, on the road from São Nicolau to Garruchos, Santo Antônio das Missões, Rio Grande do Sul, Brazil; bottom, holotype, photo taken just after capture.

Fig. 4 in Descriptions of five new species of the Neotropical cichlid genus Gymnogeophagus Miranda Ribeiro, 1918 (Teleostei: Cichliformes) from the rio Uruguay drainage

Fig. 4. Gymnogeophagus pseudolabiatus: top, holotype, male, MCP 35027, 92.3 mm SL, rio Sarandi III, on the road from Santana do Livramento to Quaraí, Santana do Livramento, Rio Grande do Sul, Brazil; bottom, paratype, male, MCP 35036, 81.4 mm SL) creek tributary of rio Quaraí, on road from Quaraí to Baltazar Brum railroad station, Rio Grande do Sul, Brazil.

Fig. 13 in Descriptions of five new species of the Neotropical cichlid genus Gymnogeophagus Miranda Ribeiro, 1918 (Teleostei: Cichliformes) from the rio Uruguay drainage

Fig. 13. Species of Gymnogeophagus from Rio Grande do Sul State, Brazil. a, Gymnogeophagus balzanii, male, UFRGS 9148, 131.8 mm SL, barragem Sanchuri, Uruguaiana. b, G. balzanii, female, UFRGS 7015, 86 mm SL, barragem Sanchuri, Uruguaiana. c, G. meridionalis, male, UFRGS 8404, rio Negro, BR-153, between Aceguá and Bagé. d, G. rhabdotus, male, uncat., 65 mm SL, EEA-UFRGS, Eldorado do Sul. e, G. labiatus, male, uncat., 117 mm SL, lago Guaíba. f, G. labiatus, female, uncat.,104 mm SL, Barra do Ribeiro. g, G. lacustris, male, UFRGS 16751, 128 mm SL, lagoa Corvina, Mostardas. h, G. lacustris, female, UFRGS 16751, 90 mm SL, lagoa Corvina, Mostardas. i, G. tirapare, male, uncat., rio Cacequi. j, G. tirapare, female, UFRGS 16642, rio Santa Maria, Rosário do Sul.

Fig. 12 in Descriptions of five new species of the Neotropical cichlid genus Gymnogeophagus Miranda Ribeiro, 1918 (Teleostei: Cichliformes) from the rio Uruguay drainage

Fig. 12. Gymnogeophagus lipokarenos: top, paratype, male, UFRGS 15752, 115 mm SL, arroio do Tigre, tributary of the rio Turvo, Três Passos, Rio Grande do Sul, Brazil; bottom, paratype, female, UFRGS 15743, 107 mm SL, arroio Lajeado Romana, Três Passos, Rio Grande do Sul, Brazil.