Cyprinodontiform fishes of El Salvador

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The Cyprinodontiformes are a diverse group of teleost fishes distributed in temperate, subtropical and tropical, areas of the world; they are common in freshwater systems, but they also occur in brackish and marine waters (Parenti, 1981;Nelson, Grande, & Wilson, 2016).In Asia the Cyprinodontiformes are in Madagascar, Seychelles, India, Sri Lanka, the Indo-Malaysian archipelago, and Java; in Africa around the Mediterranean Sea and from south of the Sahara Desert to South Africa and Madagascar; in Europe, Cyprinodontiformes occur mainly around the Mediterranean Sea, southeastern Spain, Italy, western Greece, and Turkey.In America from southeastern Canada south to Argentina, including the West Indies archipelago (Nelson et al., 2016).These fishes are commonly known as killifishes, topminnows, four-eyed fishes, or toothcarps (Parenti, 1981;Nelson et al., 2004) and are represented by ~2,000 valid species, distributed in 14 families (Fricke, Eschmeyer, & van der Laan, 2020).Cyprinodontiformes are secondary freshwater fishes, and some members can tolerate waters with elevated salinity levels, occasionally using coastal and marine waters for dispersal (Miller, 1966).
In El Salvador, the Cyprinodontiformes represents 10% of the freshwater fish diversity (McMahan et al., 2013), and in some watersheds, such as the Acahuapa River, members of this order reach 26% of the total species richness, and 77% of the abundances of the fish assemblage (Álvarez et al., 2017).This highlights the importance of Cyprinodontiforms in Salvadorian freshwater systems.However, the absence of accurate taxonomic keys for the identification of species in El Salvador has generated identification errors and confusion regarding the delimitation of species.Moreover, in recent years important changes in the taxonomy of the group have occurred, as well as new advances in terms of the knowledge about their distributions.Thus, our objectives were a) to present updated taxonomic information on cyprinodontiform fishes from El Salvador, including their geographical distribution and habitat use, and b) to provide a photographic taxonomic key to facilitate their identification.

MATERIALS AND METHODS
Records of cyprinodontiform fishes present in El Salvador were obtained from the scientific literature (Alda et al., 2013;Salgado-Maldonado et al., 2014), voucher specimens at the Museo de Historia Natural de El Salvador (MUHNES), the Instituto de Ciencias del Mar y Limnología, Universidad de El Salvador (ICMARES-UES), Museo Nacional de Ciencias Naturales, Madrid, Consejo Superior de Investigaciones Científicas (MNCN-CSIC) and electronic databases of the United States National Museum (USNM), University of Kansas (KU), Field Museum of Natural History (FMNH), Swedish Museum of Natural History (NRM), California Academy of Sciences (CAS), Tulane University (TU), Louisiana Museum of Natural Science (LSUMZ), and University of Michigan Ann Arbor (UMMZ) accessed via FishNet2 (http://www.fishnet2.org).The information about species composition was gathered and organized to construct a taxonomic key for the Cyprinodontiformes in El Salvador aided by the work of Poeser (1995); Bussing (2002); Miller, Minckley, and Norris (2009); Poeser (2011); Matamoros, Schaefer, Hernández, and Chakrabarty (2012) and Robertson and Van Tassell (2015).Family names are presented in evolutionary arrangement following Fricke et al. (2020) and within the families, the categories of genera and species are sorted alphabetically.English common names are included following Nelson et al. (2004), and Salvadoran Spanish common names are also included following McMahan et al. (2013).Distribution maps by species (see Digital Appendix) and photographs of each species, including both male and female for those species that present sexual dimorphism are presented.Furthermore, distributional data by species are provided.Also, some habitat use characteristics within the Salvadorean ecosystems where species occur are described, according to personal observations and available literature (e.g.Álvarez et al., 2017).Finally, unpublished, and updated data (localities) from the Museo de Historia Natural de El Salvador (MUHNES) and Instituto de Ciencias del Mar y Limnología, Universidad de El Salvador (ICMARES-UES) are included.

RESULTS
A total of 604 museum records of Cyprinodontiforms from El Salvador were compiled.Some records were excluded because they were not identified to the species level, lacked specific geographical information, or their occurrence in El Salvador has not been validated.There were only 350 records with taxonomic information at the species level (Figure 1 and Table 1 Digital Appendix) representing three families, five genera, and 11 species: Profundulidae (2 species), Poeciliidae (8 species), and Anablepidae (one species) (Table 1).Within the family Poeciliidae, Poecilia gillii and P. butleri, as reported by McMahan et al. (2013), were excluded from this revision since recent molecular evidence suggests that these species do not occur in El Salvador (Alda et al., 2013;Ho et al., 2016;Palacios et al., 2016).Poecilia mexicana and P. nelsoni were included since these species occur in the country (Alda et al., 2013;Bagley et al., 2015;Ho et al., 2016;Palacios et al., 2016).For P. gillii, molecular and phylogeographic evidence suggests that this species occurs only in the southern portion of Central America in Panama (Alda et al., 2013;Bagley et al., 2015;Palacios et al., 2016).Therefore, a review of these individuals that have been identified as "P.gillii" is suggested.While P. butleri is geographically separated from its sister taxon P. nelsoni, the distribution of P. butleri is likely restricted to North of the Trans-Mexican Volcanic Belt in northern México (Palacios et al., 2016) while P. nelsoni spans south of the Trans-Mexican Volcanic Belt from Mexico to El Salvador (Ho et al., 2016;Palacios et al., 2016).Therefore, all the records of "P.butleri" were replaced by "P.nelsoni" due to the geographical separation between both sister taxa.For P. mexicana only valid records based on molecular analyses were used (see Alda et al., 2013).(Alda et al., 2013;Ho et al., 2016;Palacios et al., 2016).Drainages: A: Río Lempa; B: Río Paz; C: Cara Sucia San Pedro; D: Río Grande de Sonsonate; E: Mandinga Comalapa; F: Río Jiboa; G: Estero de Jaltepeque; H: Bahía de Jiquilisco; I: Río Grande de San Miguel; J: Río Sirama; K: Río Goascorán; Co: Lago de Coatepeque; L: Golfo de Fonseca.Family Profundulidae: One of the few endemic fish families of Central America and Mexico (Morcillo, Ornelas-García, Alcaraz, Matamoros, & Doadrio, 2016;Matamoros, Domínguez-Cisneros, Velázquez-Velázquez, & McMahan, 2018).This family has been subject to several taxonomic reviews and changes (Morcillo et al., 2016).Previously, the only recognized genus within the family was Profundulus Hubbs 1924, however, molecular studies divided it into the genera Profundulus and Tlaloc Álvarez & Carranza 1951 with eight and four valid species respectively (Matamoros et al., 2018;Flores, 2020;Fricke et al., 2020).In El Salvador, Profundulus is represented by two species; P. guatemalensis and P. kreiseri (McMahan et al., 2013), and both species occur mainly in highland areas of the country.Both species tend to inhabit little disturbed rivers and small streams, and at upper portions of basins occur in habitats characterized by rocky substrates, well-oxygenated waters, moderate to high currents, and surrounding vegetation (riparian forest).
Profundulus kreiseri Matamoros, Schaefer, Hernández, & Chakrabarty 2012; Olomina, Escamudo de Kreiser, Kreiser's killifish (Figure 2B).Remarks: Profundulus kreiseri was originally described based on material from the Ulúa and Chamelecón Rivers in Honduras (Matamoros, Schaefer et al., 2012).It has been reported in the Atlantic slope in Guatemala and the Pacific slope in El Salvador (McMahan et al., 2013;Morcillo et al., 2016).Its distribution in El Salvador is limited to the north region of El Salvador, in tributaries of the Río Lempa basin (Fig. 1 in Digital Appendix).
Family Poeciliidae: This family is comprised of 274 species, of which ten have been described in the last decade from Middle America (Fricke et al., 2020).The family Poeciliidae is distributed from the South of the United States to the North East of Argentina (Miller et al., 2009), and its greatest diversification occurred in Central America (Rosen & Bailey, 1963;Miller, 1966).Biogeographic studies place the origin of this family in Central and South America (Reznick et al., 2017;Tagliacollo, Duke-Sylvester, Matamoros, Chakrabarty, & Albert, 2017), however, the estimated dates of origin are still debated.In El Salvador three genera are present; Poeciliopsis Regan, 1913, Poecilia Bloch & Schneider, 1801, and Pseudoxiphophorus Bleeker, 1860, with two, five, and one species respectively (McMahan et al., 2013).In general, the species of this family in El Salvador inhabit small rivers, streams, lakes, and lagoons, from clear to disturbed water, rivers and streams with little surrounding vegetation, characterized by substrate mainly composed of rocks, logs, silt, leaves, and sand, shallow waters, and moderate to low currents.
Family Anablepidae: This family is represented by a total of 19 species distributed in the Neotropics from Mexico to South America (Fricke et al., 2020).The origin of the family is still debated, with some studies suggesting that the clade originated in the Lower Cretaceous (130-110 Ma), before Africa and South America split (Rosen, 1975;Ghedotti, 2000;Hrbek et al., 2007) or between the Upper Cretaceous and the Early Palaeocene (62-67 Ma) (Reznick et al., 2017).Recent molecular studies suggest that Anablepidae originated in South America during the Oligocene (~29.6 Ma) (Amorim & Costa, 2018), followed by a separation between the oviparous brackish and marine genus Oxyzygonectes Fowler 1916 and the clade comprised by the viviparous anablepids including the brackish and marine genus Anableps Scopoli 1777 and the predominantly freshwater genus Jenynsia Günther 1866 (27.9 Ma), which eventually diverged from each other in the Miocene (12.5 Ma).

DISCUSSION
Members of the Cyprinodontiformes are among the most conspicuous fishes in Salvadorian rivers.Some species have very restricted ranges in the country, such as P. guatemalenis, P. kreiseri, and P. anzuetoi.For instance, P. kreiseri occurs in the north side of the country on the border with Honduras and Guatemala in the Río Lempa basin, while P. guatemalensis occurs in the northwest side of the country near the border with Guatemala in the Río Paz and Cara Sucia San Pedro basin.Both inhabit mountain rivers, whereas the distribution of P. anzuetoi appears to be restricted to the middle reaches of the Río Lempa basin, near to Cerrón Grande dam.The rest of the members of the Poeciliidae family and A. dowii are widely distributed in almost all the watersheds of El Salvador.The distribution of A. dowii in freshwater systems in El Salvador is unusual when compared to other countries where this species occurs close to the coasts (Miller et al., 2009;Robertson & Van Tassell, 2015), although there are records at 670 masl in Honduras (Miller, 1979), while in El Salvador this species is found at altitudes above 900 masl.
Within the genus Poecilia, several important taxonomic modifications had occurred that affect the species composition for El Salvador.In this review, five species of the genus Poecilia are considered for El Salvador, which can be differentiated morphologically based on aspects of traditional taxonomy and that is supported by molecular studies.For example, previously P. gillii was considered to be distributed in almost all Central American countries (e.g.Bussing, 2002;Matamoros et al., 2009), however, molecular phylogeographic and systematic work, revealed that the distribution of P. gillii is restricted to Panama, excluding its occurrence in El Salvador (Alda et al., 2013;Bagley et al., 2015;Ho et al., 2016;Palacios et al., 2016).While other molecular studies concluded that P. mexicana is widely distributed in Central Mexico up to Panama on the Pacific and Atlantic slopes (Alda et al., 2013;Bagley et al., 2015;Ho et al., 2016;Palacios et al., 2016).Also, P. nelsoni was separated from P. butleri limiting its distribution north of the Trans-Mexican Volcanic Belt to Sonora, and P. nelsoni from South of the Trans-Mexican Volcanic Belt to El Salvador (Ho et al., 2016;Palacios et al., 2016).However, we recognize P. salvatoris as a morphologically valid species, despite a recent molecular study claims that this taxon could represent a morphotype of P. mexicana and that a review is needed (Bagley et al., 2015;Ho et al., 2016).

TABLE 1
Records of Cyprinodontiformes of the El Salvador by drainage.
*Recently added to the Salvadoran fish fauna based on molecular studies

TABLE 1
Voucher specimens in ichthyological collections, year of collection, and geographical coordinates.Original geographical coordinates are represented with an asterisk (*), otherwise coordinates correspond to original descriptions established according to the databases.