A new species of Astyanax (Characiformes: Characidae) from Costa Rica and Panama, with a key to the lower Central American species of the genus

Abstract

Astyanax anai, a new species of characid fish, is described from the Sixaola River basin, eastern Costa Rica-western Panama, Central America. The new species can be distinguished from all other congeners by the following combination of characters: premaxillary teeth 4-5 at the inner series and 4-6 at the outer series; maxillary teeth tricuspid, 2-4; predorsal scale series irregular and incomplete, with an unscaled space behind tip of supraoccipital process and 12-14 scales; lateral line scales 34-39; humeral region with a conspicuous black and rounded to horizontally ovate spot and two diffuse brown and vertically elongate bars (the first through the rounded to horizontally ovate spot, the second 2-4 scales behind the first); body depth 36·6-42·3% of standard length (L ); midlateral stripe formed by a series of 10-14 anteriorly-directed dermal herringbone, or chevron-shaped, marks, most apparent in juveniles and in preserved specimens, extending above the lateral line from the black humeral spot or just behind it (from the second vertical bar) to the caudal peduncle; scale rows from lateral line to base of first dorsal-fin ray 8-9; scale rows from lateral line to base of pelvic fin 7-8; pre-anal distance 53·9-61·9% of L ; total anal-fin elements 29-33; caudal spot elongated, rhomboid or rectangular, with its anterior margin surpassing the middle of the caudal peduncle, usually reaching the anal-fin insertion, posteriorly covering 4-7 principal caudal-fin rays and not extending onto the ventral and dorsal margins of the caudal peduncle, covering 3-5 horizontal scale rows. In order to test the phylogenetic relationships of the new taxon in relation to the other North and Central American species of the genus, a new phylogenetic hypothesis based on a reanalysis of the morphological matrix by Schmitter-Soto (2016) is proposed. A key to the lower Central American (southern Nicaragua to eastern Panama) species of Astyanax is also provided.

History predicts contemporary community diversity within a biogeographic province of freshwater fish

“…Fish were captured using a handheld seine with 1‐mm mesh size and cast nets and identified in the field if possible. When taxonomic identifications were uncertain, we collected voucher specimens of each species by humanely euthanizing individuals with an overdose of MS‐222 and keying them in the laboratory using the keys in Angulo et al (2018), Angulo and Gracian‐Negrete (2013), Bussing (1998), Matamoros et al (2013) and Schmitter‐Soto (2017). For species in the family Cichlidae, we modified the key in Bussing (1998) using updated taxonomic information from Říčan et al (2008) and Říčan et al (2016), see Appendix S1).…”

Claves para la identificación de los peces de las aguas continentales e insulares de Costa Rica. Parte I: Familias

“…Tales avances se han visto reflejados en diversas publicaciones científicas incrementando el número total de especies reconocidas para el país (e.g., Schmitter-Soto, 2017;Angulo et al, 2015;en prep., & Álvarez-Calderón et al, 2018; entre otros), ampliando los ámbitos de distribución vertical y/o geográfico conocido para varias especies (e.g. Angulo et al, 2015;2017;2018a, b;Arguedas, 2019;Rodríguez-Arias et al, 2019, & Angulo et al, 2020 e incluso añadiendo/describiendo nuevas especies para la ciencia, algunas de ellas con localidades tipo en Costa Rica (e.g., Matamoros et al, 2013;Angulo & Gracian-Negrete, 2013;Angulo et al, 2018a, & Ota et al, 2020, entre otros. Dado esto, el conocimiento sobre la composición taxonómica de la fauna íctica (de aguas continentales e insulares) costarricense ha cambiado, de forma sustancial, en los últimos años; no solo por la adición de múltiples especies y taxones supra-específicos sino también como consecuencia de diversos rearreglos y cambios taxonómicos en los diferentes niveles jerárquicos, principalmente géneros, pero también familias y órdenes Nelson et al, 2016;Angulo et al, 2017;2018;2020 en prep.…”

“…), esto tomando como base la publicación de Bussing (1998). Bussing (1998) listó inicialmente un total de 34 familias de peces habitando las aguas continentales e insulares de Costa Rica, no obstante, 2017;2018a;2020, en prep. ) reportan un total de 53 familias.…”