Tlaloc portillorum ( Matamoros & Schaefer 2010 )

Henríquez, Carlos M., Sarmiento-Marina, Yessenia, Salgado-Maldonado, Guillermo & Matamoros, Wilfredo A., 2024, Range extension of the Honduran endemic killifish Tlaloc portillorum (Matamoros & Schaefer 2010) (Cyprinodontiformes: Profundulidae): new records from the upper reaches of the Patuca and Choluteca Rivers, Zootaxa 5403 (3), pp. 396-400 : 396-399

Tlaloc portillorum ( Matamoros & Schaefer 2010) ( Fig. 1B )

was described with material from the Ulúa River basin. Until now the only known localities for the species came from the type series reported in the original description ( Fig. 1A , Table 1 ), a few additional localities in the Nacaome River reported by Salgado-Maldonado et al. (2014, 2015) and one more locality very close to the type locality reported by Pinacho-Pinacho et al. (2015). Although, T. portillorum was described more than a decade ago, basic knowledge about its biology, ecology and life history are still lacking. To date, there are only a few papers in the scientific literature dealing with the species (e.g. Pinacho-Pinacho et al. 2015; Salgado-Maldonado et al. 2014, 2015), and these are focused on describing their parasitic associations.

In Central America, Honduras is one of the countries with the lowest number of endemic freshwater fish species (4), and T. portillorum is the only endemic profundulid ( Contreras-MacBeath et al. 2022; Matamoros et al. 2009). Tlaloc portillorum is known for localities in the upper reaches of the Ulúa River near the city of Siguatepeque , in the Department of Comayagua ( Fig. 1A ), as well as localities of the Nacaome River in the towns of Lepaterique and Ojojona in the Department of Francisco Morazán. In the original description, T. portillorum is reported to inhabit shallow creeks with very small width (3–5 m) and bottoms dominated by large cobblestone ( Matamoros & Schaefer 2010). It was found in sympatry with Oreochromis niloticus (Linnaeus 1758) and Rhamdia laticauda (Kner 1858) ( Matamoros & Schaefer 2010) .

Regarding its conservation status, T. portillorum is listed as endangered in the IUCN red list ( Lyons & Matamoros 2020). The criteria for placing the species under this category is that at the time the IUCN report was made, there was a limited number of known localities for the species ( Lyons & Matamoros 2020) and some of these localities are under critical anthropogenic pressure (W.A. Matamoros pers. Obs.). It is paramount for conservation planning to know in the most comprehensible way the actual species distributional range, which will allow conservation managers to take more accurate decisions.

The aims of this study are twofold: First, to build the most comprehensive distribution map of T. portillorum , based on data from the scientific literature, collection records and our own surveys. Second, to provide a more complete description of the habitats where T. portillorum occurs.

Specimens were collected as part of surveys performed by the first author in order to complete his undergraduate professional practice in 2014 ( Henríquez 2014). Sampling was carried out in the upper reaches of the Río Patuca in the Honduran department of Francisco Morazán. Additionally , as part of a T. portillorum life history and diet study, we sampled specimens of T. portillorum between the months of April to July of 2023 in tributaries of the Choluteca, Nacaome and Ulúa basins ( Fig. 1A ; Table 1 ). We also gathered distributional data from the scientific literature and a limited number of records were added from the Fishnet 2 database aggregator (www.fishnet2.net, accessed 2023-08-04). In the field, fish were collected with the use of dip-nets and a three m long and 1.80 m high seine with a 5 mm mesh size. In each locality, fish were sampled in all possible habitats including currents, riffles, and pools. Since we knew that T. portillorum specimens tend to hide underneath boulders, rocks and vegetation in the river undercut bank, we put special efforts into sampling this type of habitat. The sampling effort consisted of 30–40 minutes at each site. After capture, individuals were euthanized in a clove oil solution and then transferred to 10% formalin or to pure ethanol for tissue preservation. After 10–12 days, formalin-fixed specimens were transferred to 70% ethanol for long-term storage.

Species identification was based on characters provided by Matamoros & Schaefer (2010). The specimens were determined to belong to T. portillorum ( Fig. 1B ) due to the lack of a humeral spot and having less than half of the caudal fin covered by scales, with a prominent lower jaw that protrudes and covers the upper jaw. The new records of T. portillorum in tributaries of the Choluteca River and the Patuca River in conjunction represent a substantial range expansion of at least ~120 km ( Fig. 1A ). We recorded T. portillorum specimens at lower stream order creeks and never in the main river channels, at altitudes ranging from ~570 to ~1670 masl. The lower altitude localities were found in the Comayagua valley, close to the city of Comayagua ( Table 1 ). The highest localities are reported from the upper reaches of the Choluteca, Nacaome and Patuca Rivers ( Table 1 ). These high-altitude lower stream order creeks where T. portillorum were found, are usually shallow (from a few centimeters of water depth to up to 50–70 cm of water depth). Creeks are generally very narrow, ranging from canals of less than one meter in width to more than 10 meters ( Fig. 1C ), with sediments dominated by large boulders, rocks and cobblestone. Frequently T. portillorum specimens are found underneath large boulders and rocks in both flowing current and pools ( Fig. 1C ), as well as hidden in vegetation along the riverbank undercut. In our surveys, T. portillorum was found in sympatry with other species including Poecilia mexicana Steindachner 1863 , Alfaro huberi (Fowler 1923) , Rhamdia laticauda (Kner 1858) , Phallichthys amates (Miller 1907) , Astyanax aeneus (Günther 1860) , Amatitlania nigrofasciata (Günther 1867) and Parachromis motaguensis (Günther 1867) .

Carr Jr. & Giovannoli (1950) surveyed the Choluteca River and did not report any Profundulidae species in this river. Later on Matamoros et al. (2009) in a major river drainage checklist of Honduran freshwater fishes, surveyed the Choluteca and the Patuca River and at that time they also fail to detect any Profundulidae species in these two rivers. Although the Choluteca and Patuca Rivers are among the most important rivers in Honduras, their ichthyofauna remains poorly known. Besides the above-mentioned publications, no other attempts have been made to increase the knowledge of the distributional patterns and ecology of the fish communities of these rivers. Our results demonstrate that the distributional range of T. portillorum is larger than previously thought, and that it extends to localities approaching drainages in eastern Honduras in the Mosquitia-San Juan Ichthyological province ( Matamoros et al. 2012, 2015), the Atlantic slope of Central America and the upper reaches of the Choluteca River in the Pacific slope.

Regarding the type of habitats in which T. portillorum is found, they generally coincide with the habitats reported in Matamoros and Schaefer (2010). This fish is found at higher altitudes lower order streams, ranging from ~570 to ~1670 masl. These creeks are all characterized by having smaller widths, from less than a meter to ~ 10 meters, with bottoms dominated by boulders, rocks, gravel and cobblestone. The number of species that share habitats with T. portillorum has been increased from what was previously known and includes more poecilids and cichlids.

Figures

FIGURE 1. (A) Map of Honduras showing localities where Tlalocportillorum hasbeen collected.Dashed lines depict majorriver basin borders (basin names in blue font with white background). Major city names in uppercase and bold font. (B) Photograph of live specimen of T. portillorum (5.5 cm standard length) from the Guacerique River (longitude= -87.109, latitude= 14.033), a tributary of the Choluteca River basin. (C) Habitat of T. portillorum. From the Guacerique River, tributary of the Choluteca River basin (longitude -87.111, latitude 14.032).