Profundulus hectori, Domínguez-Cisneros & Velázquez-Velázquez & Domínguez-Domínguez & Beltrán-López, 2025

Profundulus hectori , new species urn:lsid:zoobank.org:act:

( Figs. 1, 2A–B; Tabs. 1–2)

Holotype. MZ-UNICACH GoogleMaps 7812, male, 51.15 mm SL, Mexico   GoogleMaps , Chiapas   GoogleMaps , Sabinal River   GoogleMaps , tributary of Grijalva River   GoogleMaps , 1 km from Monterrey Institute of Technology   GoogleMaps and Higher Education   GoogleMaps , Tuxtla   GoogleMaps campus, in the municipality of Tuxtla Gutiérrez, Chiapas, 16°45’36.25”N 93°12’18.62”W, altitude 611 m, 13 Apr 2002, E. Velázquez-Velázquez.

Paratypes. All from Mexico. MZ-UNICACH 006, 16 (1 c&s), 38.89–51.15 mm SL, same data as holotype. MZ-UNICACH 3100, 9, 35.83–57.07 mm SL, Chiapas, Copainalá stream GoogleMaps , in the municipality of Copainalá, 17°3’29.43”N 93°11’50.97”W, 23 Apr 2009, M. Anzueto-Calvo & E. Velázquez-Velázquez. MZ-UNICACH 4332, 4, 38.42–53.24 mm SL, Chiapas, Pozas del Chorreadero   GoogleMaps , in the municipality of Chiapa de Corzo, 16°45’19.04”N 92°58’17.55”W, 23 Oct 2010, M. Anzueto-Calvo & L. Velázquez Valencia. MZ-UNICACH 5085, 18, 38.42–70.79 mm SL, Chiapas, Nandalumí stream, in the municipality of Chiapa de Corzo, 16°43’22.25”N 92°59’3.01”W, 29 Nov 2016, M. Anzueto-Calvo & A. Basulto. MZ-UNICACH 5752, 4, 40.58–43.53 mm SL, Chiapas, stream of the Rancho San José, Colonia Cuauhtémoc, in the municipality of Villaflores, 16°20’45.07”N 93°12’43.68”W, 26 Dec 2014, M. Anzueto-Calvo & E. Velázquez-Velázquez. MZ-UNICACH 6586, 17 (1 c&s), 37.60–58.40 mm SL, Chiapas, stream of the Tierra y Libertad, in the municipality of Jiquipilas, 16°29’16.07”N 94°5’55.21”W, 15 Apr 2015, A. Gómez & E. Velázquez-Velázquez. MZ-UNICACH 7569, 15 (6 c&s), 40.77–68.25 mm SL, Chiapas, El Arenal stream, in the municipality of Cintalapa, 16 °26’3.82”N 94°4’54.28”W, 12 Oct 2021, E. Velázquez-Velázquez & S. Domínguez-Cisneros. MZ-UNICACH 7570, 4, 38.19–65.05 mm SL, Chiapas,

Waterfall of the Novillero River , in the municipality of Cintalapa , 16°25’51.21” N 94 °5’59.08”W, 20 Oct 2021, E. Velázquez-Velázquez & S. Domínguez-Cisneros. MZ-UNICACH 7620, 4 (1 c&s), 40.57–59.38 mm SL, Chiapas, Sabinal River , Pozas de Berriozabal, in the municipality of Tuxtla Gutierrez, 16°45’59.57”N 93°13’48.65”W, 16 Dec 2022, E. Velázquez-Velázquez & M. Anzueto-Calvo. MZ-UNICACH 7622, 10 (2 c&s), 38.53–56.50 mm SL, Oaxaca, upper course of the Negro River, Colonia Rudolfo Figueroa, in the municipality of San Miguel Chimalapa, 16°33’10.46”N 94°10’54.90”W, 27 Jan 2020, E. Velázquez-Velázquez & M. Anzueto-Calvo GoogleMaps .

Diagnosis. Profundulus hectori is a member of genus Profundulus by the presence of a small mesethmoid, crescent-shaped, that does not extend beyond the margin of the vomer, the autopterotic fossa is large and humeral spot present. The following combination of characters distinguishes P. hectori from congeners: presence of a set of large black spots on the scales on the sides of the body ( Figs. 2A–B) (absent in P. guatemalensis , P. kreiseri , P. adani , and P. mixtlanensis ). The set of black spots are equal to or greater than 50% of the diameter of the pupil in P. hectori , whereas in P. balsanus , P. parentiae , and P. oaxacae (Meek, 1902) , the set of black spots are small (less than 50% of the diameter of the pupil). It is distinguished from P. chimalapensis by a larger number of scales on the lateral line (30–33) ( vs. 29–32) and a larger number of predorsal scales (18–24) ( vs. 18–21) ( Tab. 2). Profundulus hectori can be further differentiated from P. punctatus by the origin of the dorsal fin positioned at a vertical line slightly anterior to the origin of the anal fin ( vs. origin of the dorsal fin positioned at a vertical line posterior to the origin of the anal fin) ( Figs. 3A–B). The neural and hemal spines of the preural centra 2 in P. hectori has no serrations along its edges ( vs. serrations along its outer edge in P. punctatus ) ( Figs. 4A–B). The lacrimal bone has a lateral extension of round or blunt shape in P. hectori ( vs. the lacrimal bone with a lateral extension of triangular shape in P. puntatus ) ( Figs. 5A–D).

Description. Morphometric data appear in Tab. 1. Body slender, sub-cylindrical; head compressed, large (27.03–32.93%); the interorbital broad (39.95–53.15%) and typically concave or nearly flat. Ascending premaxillary process short and broad and bluntly rounded at the tip. Mouth subterminal, lower jaw broad, heavy and protruding so that upper jaw is included. Dorsal fin rounded in both males and females with its basal length large (11.10–22.70%). Anal fins of males rounded, slightly elongated in females ( Figs. 2A–B). Caudal peduncle relatively short (13.66–21.41%). All bones in the caudal fin skeleton are directly or indirectly associated with the last compound centrum of the vertebral column; median hypural plate divided into subequal parts by an open groove ( Figs. 4C–D). Meristic traits are as follows ( Tab. 2).

Coloration in alcohol. In both sexes, head and flank pale brown; the body is dark gray; the humeral spot is very evident; fins hyaline in females, hyaline with pale brown pigmentation in males.

Coloration in life. Live coloration description is largely based on two live specimens ( Figs. 2A–B). The form and coloration of the nuptial adult male are shown in Fig. 2A. The male is brown-orange on nearly the whole body. A golden yellow blotch covers the operculum and reaches the base of the pectoral fin. A dark band on the sides of the body, with large irregular dark-brown spots on the scales, runs from just behind the pectoral fin to the base of the caudal fin. The base of dorsal and anal fin yellowish, with greater intensity on the edges. The female is brown-orange on nearly the whole body, with diffuse dark band on the anterior half of the side of the body. A golden yellow blotch covers the operculum and reaches the base of the pectoral fin. All fins yellowish. Most of the body dark, often with irregular brown-dark spots on the scales on the sides of the body to the caudal fin ( Fig. 2B).

Sexual dimorphism. The largest specimen recorded was a male ( 83.9 mm SL), while the maximum size recorded in a female was 77.9 mm SL. In males and females the dorsal and anal fins have a similar morphology ( Figs. 2A–B); the males have contact organs or spinules on the surface of the scales and the middle rays of the anal and dorsal fins; this is the most notable, though not striking, difference between males and females.

Geographical distribution. On the Atlantic slope: Springs and streams tributaries of the Grijalva Rivers in Chiapas, Mexico ( Fig. 6): Sabinal River ( Figs. 7A–B), Cintalapa River ( Fig. 7C), Negro River, the Venta River, Bombaná River, Chiapilla River, Nandalumí streams, Natura and vos (springs) and Los Amates River, all tributaries of the Grijalva River basin. On the Pacific slope: Novillero River ( Fig. 7D) and the Arenal River.

Ecological notes. The type-locality is near the city of Tuxtla Gutierrez, capital of the state of Chiapas, along the Sabinal River, a tributary of the Grijalva River, at an altitude of 658 m. The streams are surrounded by riparian vegetation with presence of Sabino trees ( Taxodium huegelii ) ( Figs. 7A–B). The substrate was composed of pebbles, sand and Sabino roots; the marginal vegetation was composed predominantly of scrubland and herbaceous banks, where the specimens were found. The new species was found in sympatry at the type-locality with Tlaloc labialis (Günther, 1866) , Poeciliopsis pleurospilus (Günther, 1866) , Poecilia sphenops Valenciennes, 1846 , Chiapaheros grammodes (Taylor & Miller, 1980) , Astyanax aeneus (Günther, 1860) , and the non-native fish Poecilia reticulata Peters, 1859 , which is currently considered a highly invasive species. This species is commonly known as Escamudo del Grijalva in Spanish-spaeking countries, or as Grijalva killifish in english-speaking countries.

Etymology. In recognition of his many contributions to the study and conservation of freshwater fishes in Mexico, this species is named after our friend and colleague, the Mexican ichthyologist Hector Espinosa Perez, recently deceased. A noun in a genitive case.

Conservation status. Profundulus hectori is known as a native and endemic freshwater species of Chiapas, Mexico. Its total population size and population characteristics are unknown. However , ichthyological surveys suggest that this species is common at some localities where it occurs. A number of potential threats to aquatic habitat exist in Chiapas, including deforestation associated with land-use changes, pollution from agriculture, exotic species, and urban and hydropower development. While the direct impacts of these threats on population status are unknown, they are producing continuous inferred declines in habitat quality and, potentially, availability. Therefore, the new species can be listed as Least Concern (LC), according to the IUCN criteria ( IUCN, 2024) .

Molecular analysis. Phylogenetic analyses (BI and ML) based on the three concatenated genes suggest that the new species, P. hectori , forms a clade with P.

chimalapensis as its sister species. Together, P. hectori and P. chimalapensis were recovered as sister species to P. oaxacae , with strong support in both analyses. This clade of three species is, in turn, the sister clade to P. punctatus , also with high support

( Fig. 8). Although the phylogenetic relationships among P. hectori , P. chimalapensis , P.

oaxacae, and P. punctatus varied depending on the gene used, P. hectori was consistently recovered as a monophyletic group with high support and as part of the same clade with the same sister species. The results of those genes are presented as supplementary material ( Figs. S1, S 2 and S 3). The specimens identified as P. chimalapensis in Arroyave et al. (2024) were nested within the clade of the new species, P. hectori ( Fig. S1). The mean genetic p -distances based on mt- nd2 between P. hectori and congeners ranged from 3.86% (with P. oaxacae ), 4.16% (with P. chimalapensis ), 4.44% (with P. punctatus ) to 15.55% (with P. adani ) ( Tab. 3).