Thorichthys, Meek, 1904

ELÍAS, DIEGO J., BETANCOURT-RESENDES, ISAÍ, DÍAZ-FLORES, ALEJANDRO, CAMAK, DAVID T., DOMÍNGUEZ-DOMÍNGUEZ, OMAR, ARTIGAS-AZAS, JUAN M., PILLER, KYLE R. & MCMAHAN, CALEB D., 2025, Evolutionary history of the polymorphic Coatzacoalcos River endemic Thorichthys panchovillai (Cichliformes: Cichlidae), Zootaxa 5618 (1), pp. 29-46 : 35

Phylogenetics of Thorichthys and T. panchovillai

Sequence length in our final alignment (n = 55) ranged from 784 to 1065 base pairs (bp), and only two sequences were shorter than 1000 base pairs, T. panchovillai FMNH 152716.2 (784 bp) and T. panchovillai FMNH 151316.2 (833 bp). Both Bayesian and maximum likelihood phylogenetic analyses recovered two major clades within the genus Thorichthys ( Fig. 2 ), supported by Bayesian posterior probabilities (BPP = 1) and bootstrap support values (BS =100). One clade was composed of three species ( T. affinis , T. meeki , and T. pasionis ; Fig. 2 ) and a deeply divergent sister lineage of samples identified as T. helleri from the Grijalva-Usumacinta Area of Endemism (AoE sensu Elías et al. 2020), hereafter referred to as T. cf. helleri ( Fig. 2 ). It is worth noting that samples of T. affinis and T. meeki were not recovered as reciprocally monophyletic ( Fig. 2 ). The second major clade was composed of six species (viz. T. aureus , T. callolepis , T. helleri , T. maculipinnis , T. panchovillai , and T. socolofi ; Fig. 2 ). Within this clade we inferred two strongly supported sub-clades (BPP = 1, BS = 84; Fig. 2 ), one which includes two species, T. callolepis and T. maculipinnis (BPP = 1, BS = 100), and the other clade comprised of T. aureus , T. helleri , T. panchovillai , and T. socolofi . Phylogenetic relationships of this clade recovered T. aureus as the sister of a clade comprised of T. helleri , T. panchovillai , and T. socolofi with strong support (BPP = 1, BS = 84), in which T. helleri was recovered as the sister of T. panchovillai + T. socolofi with strong support (BPP = 1, BS = 92; Fig. 1 ); ( T. aureus , ( T. helleri , ( T. panchovillai , T. socolofi ))) ( Figs. 2 and 3 ).

Figures

FIGURE 1. (A)Geographic locationof the Coatzacoalcos watershed and its adjacent river basins intheAtlantic slope of Southern Mexico. (B) River sub-basins within the Coatzacoalcos watershed, 1) Coatzacoalcos sub-basin [pale grey], 2) Jaltepec sub-basin [mint], 3) Tolosa sub-basin [pink], 4) Chachijapa sub-basin [olive], and 5) Uxpanapa sub-basin [orange]. River sub-basin names follows Instituto Nacional de Estadística y Geografía (INEGI) Mexico. (https://www.inegi.org.mx/temas/hidrografia/). Dashed line delineates political boundaries at the state level within Mexico.

FIGURE 2. (A) Phylogenetic relationships of Thorichthys, topology inferred under bayesian approach. Support values for the nodes represent Bayesian Posterior Probabilities [BPP] and bootstrap support values [BS]; BPP / BS -. Asterisk represents samples of T. affinis from the type locality, Lake Petén Itzá, Guatemala. (B) Geographic locality of samples/sequences of T. affinis [red triangle], T. cf. helleri [yellow square] T. meeki [red square], and T. pasionis [grey square]. Hydrographic regions: Papaloapan basin [1], Coatzacoalcos basin [2], and Tonala basin [3]. (C) Geographic locality of samples/sequences of T. aureus [blue circle], T. callolepis [teal circle], T. helleri [yellow circle] T. maculipinnis [orange circle], T. panchovillai [purple circle], and T. socolofi [green circle]. For locality information see Table 1. Hydrographic regions: Grijalva-Usumacinta [4] and Polochic- Cahabón [5] areas of endemism sensu Elías et al. 2020, and Motagua basin [6].

FIGURE 3. Estimated genetic divergence using the p-distance (grey triangles) and the Kimura 2 parameter model (black circles) and estimated standard error based on the only-Thorichthys alignment. Comparison between the two major clades of Thorichthys inferred with the mitochondrial Cytb marker and between T. panchovillai (n=12) and closely related species: T. callolepis (n =4), T. maculipinnis (n =3), T. helleri (n =3), T. socolofi (n =4), and T. aureus (n =3).