Tehuana

Villalobos, José Luis & Alvarez, Fernando, 2010, Phylogenetic analysis of the Mexican freshwater crabs of the tribe Pseudothelphusini (Decapoda: Brachyura: Pseudothelphusidae), Zoological Journal of the Linnean Society 160 (3), pp. 457-481 : 474

TEHUANA

The genera Tehuana and Pseudothelphusa compose the clade that follows node 9, defined by a straight cervical groove (character 13), an efferent branchial channel opening that is square in section (character 21), and one spine on the lateral margin of the mesial process of the first male gonopod (character 66).

The genus Tehuana is defined by ten attributes, among which is the presence of a mesodistal prominence on the first male gonopod, which is a diagnostic character of the genus (node 10). Other important characters are: the general form of the first male gonopod, with a slender and cylindrical proximal half and compressed distally (character 34); the position of the lateral constriction on the middle portion of the gonopod (character 36); and the presence of a strong and often circular carina on the inner surface of the proximal lobe of the caudo-marginal projection (character 57).

Tehuana lamothei and Tehuana diabolis remained apart from the rest of the species in the genus in all of the trees. Among the characters that separate T. lamothei , the most important one is the orientation of the proximal lobe of the caudo-marginal projection, which forms a 90° angle with respect to the main longitudinal axis of the gonopod. In the case of T. diabolis , two characters support its separation: a straight posterior margin of the carapace (character 17) and the orientation of the proximal lobe of the caudo-marginal projection, which is parallel with the main longitudinal axis of the gonopod (character 53).

The position of the rest of the species of Tehuana presented two alternatives through the ten trees obtained in the heuristic search (node 11). The difference between them was the position of T. chontalpaensis : first as a sister species of the clade formed by T. poglayenorum and T. veracruzana , and second as a sister species of the clade formed by T. poglayenorum , T. veracruzana , T. jacatepecensis , T. complanata , and T. lamellifrons ( Fig. 6 ). Neither the majority nor the strict consensus trees show the position of T. chontalpaensis to be completely resolved. Interestingly, T. chontalpaensis occupies an intermediate position, in western Tabasco, within the range of the genus with a group of species to the north-east of its range in central Veracruz ( T. diabolis , T. poglayenorum , and T. veracruzana ) and another group present to the southwest, in southern Veracruz and Oaxaca ( T. complanata , T. jacatepecensis , and T. lamellifrons ).

Figures

Figure 6. Detail of the complete tree obtained for the tribe Pseudothelphusini, showing alternative arrangements of the species of Tehuana (A, B) and the majority consensus tree (C). The position of Tehuana chontalpaensis, with an intermediate gonopod morphology, is not compeltely resolved.