Revision of the Astyanax orthodus species-group (Teleostei: Characidae) with descriptions of three new species

Abstract

The Astyanax orthodus species-group includes nine species: Astyanax boliviensis sp. nov., A. bopiensis nom. nov., A. embera sp. nov., A. gandhiae sp. nov., A. moorii comb. nov., A. orthodus, A. superbus, A. villwocki and A. yariguies comb. nov. The group is diagnosed by the presence of a series of pinnate-shaped marks (chevrons) located along the lateral midline, which extends from the humeral region to the caudal peduncle. Astyanax bopiensis nom. nov. is proposed as a substitute name for Astyanacinus multidens, which, along with Astyanax yariguies comb. nov., we reassign to Astyanax.We also propose the synonymy of Astyanacinus with Astyanax. The members of the A. orthodus species-group are distributed in northwestern South America, occurring in the Patia River drainage (A. embera sp. nov.) of the Pacific coast of Colombia, the Atrato River Basin (A. orthodus), the Magdalena River Basin (A. yariguies comb. nov.) of Caribbean Colombia, streams of the southern flank of the Andes of the Orinoco Basin in Venezuela (A. superbus), in the upper Amazon River Basin of Colombia, Ecuador and Peru (A. villwocki, A. gandhiae sp. nov.), from the upper Paraguay River (A. moorii comb. nov.), the Madidi and Mamore Rivers, Bolivia (A. boliviensis sp. nov. and A. bopiensis nom. nov.). All species currently included in Astyanacinus are reassigned to the Astyanax orthodus species-group.

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

“…However, earlier revisions (Hildebrand, 1938;Loftin, 1965), as well as recent papers (Smith & Bermingham, 2005) and expeditions assessing part or the totality of the freshwater fish fauna of Panama, fail to list A. orthodus eastward to the Sixaola River basin, contradicting Bussing's (1987Bussing's ( , 1998 conclusion. Moreover, other authors (Lima et al, 2003;Ruiz-C et al, 2011;Maldonado-Ocampo et al, 2012;Ruiz-C et al, 2018), in accordance with the foregoing, have restricted A. orthodus to western Colombia (i.e. Atrato River basin), generating some doubt about the identity of the specimens listed as A. orthodus by Bussing (1987Bussing ( , 1998 and other authors, for Costa Rica and Panama. A detailed examination of museum specimens catalogued as A. orthodus, both from Costa Rica-Panama and Colombia, including type material from Colombia as well as other sympatric and related species, revealed that specimens from Costa Rica and Panama represent a previously unknown species (different from A. orthodus sensu lato as well as from the other lower Central American species of the genus) which is described here.…”

“…Bremer support was calculated in TNT using suboptimal trees with up to 15 steps more than the fundamental trees. (Garutti & Britski, 1997;Garutti, 1998;Garutti & Langeani, 2009;Lucena & Soares, 2016) by the presence of a black and rounded to horizontally ovate humeral spot (covering 3-4 scales horizontally and 2-3 scale series vertically) and two very diffuse brown and vertically elongate spots (or bars) in the humeral area (the first through the black humeral spot, the second 2-4 scales behind the first), being more evident in preserved specimens (v. not as described above in other congeners Ruiz-C et al (2018), by the presence of a midlateral stripe formed by a series of usually 10-14 anteriorly directed dermal herringbone or chevron-shaped marks most apparent in juveniles and in preserved specimens, which extends above the lateral line from the humeral spot or just behind it (from the second vertical bar) to the caudal peduncle (v. absent or not as described above in the other species of the group), as well as by the presence of a black caudal spot of variable size and shape that continues over the median caudal-fin rays (v. absent or not as described above in the other species of the group).…”

“…Morphological data cited in the diagnosis from other species of Astyanax were based on original descriptions, additional literary resources (Eigenmann & Ogle, 1907;Eigenmann, 1921;Hildebrand, 1938;Garutti & Britski, 1997;Bussing, 1998Bussing, , 2008Garutti, 1998;Garutti & Langeani, 2009;Dagosta, 2011;Maldonado-Ocampo et al, 2012;Torres-Mejia et al, 2012;Marinho & Birindelli, 2013;Marinho & Ohara, 2013;Lucena & Soares, 2016;Schmitter-Soto, 2016 andRuiz-C et al, 2018) and additional analysed specimens. Institutional abbreviations followed Sabaj (2016): CAS, Chinese Academy of Sciences, Institute of Zoology, Beijing, PDR China; DZSJRP, Departmento de Zoologia e Botânica, Universidade Estadual Paulista Júlio de Mesquita Filho (UNESP), Campus de São José do Rio Preto, São Paulo, Brazil; FMNH, Field Museum of Natural History, Geology Department (slide collection), Chicago, IL, U.S.A.; MZUSP, Museu de Zoologia da Universidade de São Paulo, São Paulo, Brazil; USNM, Table II) was performed using the software TNT 1·1 (Goloboff et al, 2008).…”

“…Furthermore, A. anai differs numerous other Astyanax spp., as follows. Astyanax boliviensis by the following combination of characters: pre-anal distance 53·9-61·9% of L S , mean 57·6% (v. 60·8-65·9% of L S , mean 63·6%); lateral line scales 34-39, usually 38 (v. 39-42, usually 40); chevrons without distal extensions (v. present;Ruiz-C et al, 2018); caudal spot restricted to the caudal fin and adjacent caudal peduncle, not extending anteriorly as a continuous dark line or stripe on side of body (v. not restricted to the caudal fin and adjacent caudal peduncle, extending anteriorly as a continuous dark line or stripe on side of body). Astyanax bopiensis by the following combination of characters: maxillary length 34·3-45·7% of L H , mean 42·2% (v. 46·7-58·9% of L H , mean 50·6%); maxillary teeth 2-4 (v. 7-13); post-orbital head length 39·4-48·0% of L H , mean 44·7% (v. 20·8-30·4% of L H , mean 25·2%); lateral line scales 34-39, usually 38 (v. 39-42, usually 40); absence of a reticulated pattern on the sides of the body formed by dark pigment on the mediodistal margins of scales (v. present); caudal spot restricted to the caudal fin and adjacent caudal peduncle, not extending anteriorly as a continuous dark line or stripe on side of body (v. not restricted to the caudal fin and adjacent caudal peduncle, extending anteriorly as a continuous dark line or stripe on side of body).…”

“…Astyanax anai and A. orthodus share a combination of characters unique among all North and Central American congeners (i.e. predorsal scale series irregular and incomplete, with an unscaled space behind tip of supraoccipital process; humeral region with a conspicuous, black and rounded to horizontally ovate spot and two diffuse vertical humeral bars; caudal peduncle with a thick and horizontally oval black spot that continues over the median caudal-fin rays), which is only present in other South American congeners such as Astyanax bimaculatus (L. 1758), Astyanax lacustris (Lütken 1875) and A. superbus, among others (Lucena & Soares, 2016;Ruiz-C et al, 2018). The colouration pattern described above for such species was used by several authors, including Garutti & Britski (1997), Garutti (1998) and Garutti & Langeani (2009), to diagnose the 'A.…”