Tehuana Rodriguez & Smalley in Smalley, 1970

Moreno-Juarez, Eric G., Villalobos, Jose Luis & Alvarez, Fernando, 2022, Revision of the freshwater crabs of the genus Tehuana Rodriguez & Smalley in Smalley 1970 (Decapoda, Pseudothelphusidae), with the descriptions of two new species, ZooKeys 1117, pp. 1-35 : 1

Genus Tehuana Rodriguez & Smalley in Smalley, 1970

Pseudothelphusa (Tehuana) Rodríguez & Smalley in Smalley, 1970: 106 (in key).- Pretzmann 1971: 22.- Pretzmann 1972: 107; 1980: 660.- Rodríguez and Smalley 1972: 77.- Türkay 1978: 144.

Tehuana .-Rodriguez, 1982: 129; 1986: 66.- Villalobos-Hiriart et al. 1993: 285 (list).- Alvarez and Villalobos 1994: 730.-Alvarez et al. 1996: 129.-Villalobos and Alvarez 2003: 228.- Álvarez et al. 2005: 191.- Ng et al. 2008: 177 (list).- Villalobos Hiriart and Álvarez 2008: 279.-Villalobos and Alvarez 2010: 474.- Álvarez et al. 2011b: 289.- Mejía-Ortíz et al. 2011: 19 (list).- Guinot and Hendrickx 2014: 477, 478, tab. 1.- Alvarez and Villalobos 2016: 244.- Villalobos-Hiriart et al. 2019: 156, tab.1 (list).- Álvarez et al. 2020: 12, tab. 4, 20 (list).

Type species.

Pseudothelphusa lamellifrons Rathbun, 1893 [by original designation].

Diagnosis.

Carapace with dorsal surface flat, smooth, punctate, with small granulations adjacent to antero-lateral margin. Front vertically deflexed, smooth, superior border formed by low rounded tubercles, medially divided by V-shaped notch reaching inferior margin; inferior margin not distinguishable dorsally, in ventral view projected, widely bilobed. Third maxillipeds with ischium trapezoidal, slightly longer than wide; merus smaller than ischium, anterolateral margin rounded, with anterior shallow concavity; ratio exopod/ischium length 0.6 to 0.8. G1 slender, proximal half cylindrical, compressed distally, with a meso-distal lobe conical, well developed on mesial surface; principal axis with medial constriction on lateral surface and twisted towards medial suture of ventral sternites (Fig. 2 ). In mesial view, proximal half with marginal plate closing spermatic channel, border facing marginal suture with proximal fringe of long and stout setae; distal half inclined towards cephalic surface; caudal surface fused with marginal plate and expanded cephalically to form the bilobed caudo-marginal projection, distal lobe well-developed (except in T. lamothei where it is reduced), subrectangular with cephalic border rounded, distal portion can be curved proximally and separated from proximal lobe by an incision; proximal lobe well developed or reduced, trapezoidal, circular, ax-shaped or elongated proximally to reach and sometimes overlap gonopod principal axis (Fig. 2B ). Meso-distal lobe arising from distocaudal angle of mesial surface, conical, subacute, or flattened caudo-cephalically, distally rounded. In cephalic view, mesial process in longitudinal position, oval shaped, closing apical cavity, distal margin widely rounded, lateral margin straight, armed with strong median spine ( T. chontalpaensis , T. lamothei ), or with moderate or reduced triangular tooth ( T. diabolis , T. col sp. nov., T. poglayenorum , T. veracruzana ); or in transversal position, reduced, spoon shaped, with lateral margin smooth without spine or tooth ( T. ayotzintepecensis sp. nov., T. complanata , T. jacatepecensis , T. lamellifrons ). Caudo-marginal projection with the two lobes directed cephalically, distal one slightly curved mesially; proximal one, ax-shaped or elongated proximally, and inclined in different gradations; carina of inner surface partially visible. Meso-distal lobe arise from caudal corner of G1 mesial surface, commonly is well developed, conical, with subacute or rounded apex. In lateral view, distal half inclined cephalically. Caudo-marginal projection with distal lobe (partially or totally visible; inner surface of proximal lobe with circular or semicircular strong carina, extending to different extents over proximal surface. In caudal view, distal third straight, apical cavity distally directed, caudal surface ending distally in a wide and shallow concavity. Caudo-marginal projection with the distal crest of mesial surface higher or at the same level as lateral. Meso-distal lobe well developed, conical, with the apex rounded or subacute rounded, its position with respect the distal crest of mesial surface, could variate through different species. Mesial process as a longitudinal apical plate or transversal reduced with the distal surface excavated, in the first case, oval shaped, the distal margin could be widely rounded, and the lateral margin straight and armed with a strong median spine, or with a moderate or reduced triangular tooth; in the second, only partially visible. In distal view, apical cavity U-shaped, opening cephalically. Field of apical setae with 20 to 60 setae; aperture of spermatic channel in caudal position; central crest ending cephalically in acute and triangular or rounded internal angle of mesial process (Fig. 2D, E ).

Remarks.

The phylogeny presented shows Tehuana to be closely related to Disparithelphusa (Fig. 2 ); however, there are strong differences in the G1 morphology: in Tehuana it is stouter, the lateral notch on the main shaft is in the middle, the internal surface of the proximal lobe of the caudo-marginal projection is marked with a strong carina, and the meso-distal lobe arises from the distocaudal corner of the mesial surface. Álvarez et al. (2020) in their phylogenetic analysis of the family also recovered Tehuana and Disparithelphusa as sister taxa.

Distribution.

The species of Tehuana are distributed in southeastern Mexico covering the Isthmus of Tehuantepec region (Fig. 1 ) in Chiapas, Oaxaca, Tabasco, and Veracruz.

Species included.

Tehuana ayotzintepecensis sp. nov.; T. col sp. nov.; T. complanata (Rathbun, 1905); T. chontalpaensis Villalobos & Alvarez, 2003; T. diabolis (Pretzmann, 1978); T. jacatepecensis Villalobos & Alvarez, 2003; T. lamellifrons (Rathbun, 1893); T. lamothei Alvarez & Villalobos, 1994; T. poglayenorum (Pretzmann, 1978); Tehuana veracruzana ( Rodríguez & Smalley in Smalley, 1970).

Figures

Figure 1. Distribution of the species of the genus Tehuana in southeastern Mexico.

Figure 2. Schematic representation of the terminology used to describe the male first gonopod (G 1) of some Tehuana species using as examples the G 1 of A T. lamellifrons B T. veracruzana C T. lamothei D T. jacatepecensis E T. poglayenorum F T. chontalpaensis. A-C mesial view D, E distal view F lateral view. Scale bars: 1 mm (A, B, C, F); 0.5 mm (D, E). Abbreviations: ac, apical cavity; cc, central crest; cmp, caudo-marginal projection; ccmp, distal crest of the caudo-marginal projection; cdc, caudal distal crest; cpl, cephalic border of the proximal lobe; dl, distal lobe; dmp, distal border of the mesial process; hc, internal carena height; hdl, distal lobe height; hpl, proximal lobe height; ic, internal carena of the proximal lobe; imp, internal angle of the mesial process; ldc, lateral distal crest; ldl, distal lobe length; lmp, lateral border of the mesial process; lpl, proximal lobe length; ls, lateral spine; mc, medial constriction; mdc, mesial distal crest; mdl, meso-distal lobe; mp, mesial process; mpl, marginal plate; ms, marginal suture; nmp, notch of the caudo-marginal projection; pl, proximal lobe; sf, spine field; sp, spermatic pore.