Pseudothelphusa americana de Saussure, 1857 sensu stricto

(Figures. 4, 8)

Pseudo-Thelphusa americana de Saussure, 1857: 305 (type locality:? Haiti).

Potamia americana – de Saussure 1858: 436, pl. II, figs. 12, 12a.

Pseudothelphusa Americana [sic] – Smith 1870: 146.

Potamocarcinus americanus [sic] – Ortmann 1897: 317 (key).

Pseudothelphusa americana – Pocock 1889: 10 (list). – Rathbun 1898: 510 (key), 513, 533 (list), 537 (list) (in part). – Young 1900: 206 (key), 207. – Rathbun 1905: 273 (key), 283 (in part). – Coifmann 1939: 106.

Pseudothelphusa (Pseudothelphusa) americana americana – Pretzmann 1965: 4. – Bott 1968: 40, fig. 1a, b (in part). – Bott 1970: 334. – Pretzmann 1972: 101, abbs. 593–598, 643–646 (in part).

Pseudothelphusa (Pseudothelphusa) americana – Chace & Hobbs 1969: 149, figs. 42, 43e.

Pseudothelphusa americana americana – Pretzmann 1971: 22.

Pseudothelphusa (Pseudothelphusa) dugesi dugesi – Rodríguez & Smalley 1972: 80, 81, fig.12. lam. 8 (by implication) (in part).

Pseudothelphusa americana – Rodríguez & Smalley 1972: 91. – Rodríguez 1982: 134 (key), 137, fig. 89. – Villalobos-F. 1982: 221 (list). – Villalobos-Hiriart et al. 1993: 287 (list). – Villalobos-Hiriart 2005: 72, 101, 111, 123, 127, 141–143, 147, 148, 155, 177, 217, 218 (key), 222, 224–227, 229, 230, 232, 233, 256, 259, 260, 300, 307, 308, 311, 331, fig. 18, tables 1–6, appendix 1, pl. XII (in part). – Villalobos-Hiriart & Álvarez 2008: 248, 261–263, 299 (list), table 1. – Ng et al. 2008: 176 (list). – Villalobos & Alvarez 2010: 458, 459, 475, table 1, 2. – Ojeda-Escoto 2017: 19, 20, 38, 45, 46, 60, fig. 2.1, 2.2, appendix 1, 3. – Villalobos-Hiriart et al. 2019: 156, table 1. – Álvarez et al. 2020: figs. 1, 2, 4, table 1, supplementary material table 1.

Type material examined. Neotype (herein designated): male (CL 26.60 mm, CW 40.63 mm) (CNCR 35390), El Ojito Spring, pool in San Luis Apizaquito, municipality of Apizaco, 19°26’16.28”N, 98°07’00.71”W, 2,418 m asl, coll. E. Moreno & Y. Montiel, 17 August 2019.

Other material examined. Mexico –– Puebla. 2 males (CL 19.41–25.73 mm, CW 28.74–38.41 mm), 2 females (CL 16.92 mm, CW) 24.80 mm) (CNCR 355), small dam in Chignahuapan, municipality of Chignahuapan, 19°50’18.16”N 98°01’52.35”W, 2256 m asl, coll. A.Villalobos-Figueroa, May 1994; 5 females (CL 22.02–26.10 mm, CW 33.63–40.59 mm) (CNCR 13409), San Isidro River, municipality of Zacatlán de las Manzanas, 19°56‘06.29”N 97°57‘40.15”W, 2047 m asl, coll. H. Brailovsky & E. Barrera, 18 July 1991 ; 7 males (CL 12.35–20.69 mm, CW 17.84–30.75 mm), 3 females (CL 16.28–26.40 mm, CW 24.27–40.68 mm) (CNCR 25527), Ajajalpa River in the Quetzalapan cascades, municipality of Zacatlán de las Manzanas, 19°52’22.44”N 97°58’53.98”W, 2193 m asl, coll. J.L. Villalobos & J. Segura, 15 October 2000 ; 1 male (CL 22.36 mm, CW 36.45 mm), 1 female (CL 16.82 mm, CW 29.06 mm) (CNCR 26108), stream between Tizcatlacoyan and San Antonio Juárez, municipality of Tizcatlacoyan, 18°50’21.53”N 98°02’43.89”W, 1998 m asl, coll. M. Olson & A. Páez-García, 20 June 2010 ; 1 male (CL 13.56 mm, CW 20.26 mm) (CNCR 31700), stream in La Magdalena Cuauxixtla, Tecali de Herrera, 18°52’44.43”N 97°57’23.65”W, 2068 m asl, coll. R. Hernández-Austria, 15 November 2019 ; 5 males (CL 22.43–27.29 mm, CW 32.63–41.16 mm), 2 females (CL 21.67–26.45 mm, CW 31.68–40.96 mm) (CNCR 36154), Quetzalapan cascade, municipality of Zacatlán de las Manzanas, 19°52’18.70”N 97°58’53.89”W, 2193 m asl, coll. K.J. Madrigal, E. Moreno & J.L. Villalobos, 11 November 2021 ; 1 female (CL 17.02 mm, CW 25.36 mm) (CNCR 36157), spring in Michac, municipality of Chignahuapan, 19°51’3.00”N 98°3’13.00”W, 2295 m asl, coll. E. Moreno, K.J. Madrigal & J.L. Villalobos, 12 November 2021 ; 4 males (CL 18.92–22.32 mm, CW 31.92–37.07 mm), 2 females (CL 15.05–18.31 mm, CW 25.60–32.40 mm) (CNCR 36550), stream in Cuahutinchán, municipality of Cuahutinchán, 18°57’23.00”N 98°01’53.00”W, 2128 m asl, coll. K.J. Madrigal, J.L. Villalobos & J. Santillán, 29 May 2022 . –– Tlaxcala. 1 male (CL 15.03 mm, CW 24.78 mm) (CNCR 10460), spring at Apizaquito, municipality of Apizaco, 19°26’16.28”N 98°07’00.71”W, 2418 m asl, coll. E. Bonilla, 2 December 1987 ; 2 males (CL 3.95–11.11 mm, CW 7.48–19.06 mm) (CNCR 33848), stream in La Ascensión Huitzcolotepec, municipality of Xaltocan, 19°22’44.27”N 98°14’55.31”W, 2338 m asl, coll. R. Robles, 12 January 1997 ; 1 male (CL 23.31 mm, CW 37.37 mm) (CNCR 35900), tributary stream in San Miguel La Presa Dam, municipality of Ixtacuixtla, 19°22’6.87”N 98°23’42.16”W, 2347 m asl, coll. K.J. Madrigal, C.F. Vergara, J. Jiménez, A. Hernández, G. Ugarte & R. Rugerio, 16 May 2021 ; 1 male (CL 11.29 mm, CW 19.19 mm), 2 females (CL 18.74–21.06 mm, CW 31.45-35.44 mm) (CNCR 35901), same locality, date, collectors and identifier as previous record; 4 males (CL 15.40–17.77 mm, CW 27.07–30.44 mm), 1 female (CL 15.55 mm, CW 26.29 mm) (CNCR 35902), Palo Huérfano Spring, barrio de Atotonilco, municipality of Amaxac de Guerrero, 19°21’44.96”N 98°10’55.71”W 2283 m asl, coll. K.J. Madrigal & R. Rugerio, 25 May 2021 ; 1 male (CL 17.44 mm, CW 30.59 mm) (CNCR 35904), tributary stream in San Miguel La Presa Dam, municipality of Ixtacuixtla, 19°22’6.87”N 98°23’42.16”W, 2347 m asl, coll. K.J. Madrigal, C.F. Vergara, J. Jiménez, A. Hernández, G. Ugarte & R. Rugerio, 16 May 2021 ; 3 males (CL 13.90–17.22 mm, CW 22.94–28.35 mm), 1 female (CL 16.12 mm, CW 27.45 mm) (CNCR 35970), same locality as previous record, coll. K.J. Madrigal, C. Vergara & J. Jiménez, 2 September 2021; 1 male (CL 8.89 mm, CW 15.56 mm) (CNCR 36158), El Ojito Spring, pool in San Luis Apizaquito, municipality of Apizaco, 19°26’16.28”N 98°07’00.71”W, 2418 m asl, coll. E. Moreno, K.J. Madrigal & J.L. Villalobos, 10 November 2021 ; 1 male (CL 19.45 mm, CW 32.09 mm), 4 females (CL 16.89–23.21 mm, CW 29.37–39.28 mm) (CNCR 36508), stream in La Ascensión Huitzcolotepec, municipality of Xaltocan, 19°25’24”N 98°12’34”W 2338 m asl, coll. K.J. Madrigal & C.F. Vergara, 15 April 2022 . –– Hidalgo. 4 males (CL 9.92-19.27 mm, CW 16.96–32.88 mm), 4 females (CL 8.16–18.14 mm, CW 13.90–29.85 mm) (CNCR 340), spring in Ventoquipa, municipality of Santiago Tulantepec de Lugo, 20°02’03.99”N 98°20’17.06”W, 2204 m asl, coll. A.E. Rabling, 16 April 1967 ; 1 male (CL 14.51 mm, CW 24.51 mm) (CNCR 12925), small springs tributaries to Tula River in Mixquiahuala, municipality of Mixquiahuala de Juárez, 20°14’18.16”N 99°12’42.67”W, 1969 m asl, coll. B. Barrera, 10 July 1994 ; 9 males (CL 8.50–16.73 mm, CW 15.13–27.75 mm), 8 females (CL 12.23–19.20 mm, CW 20.51–31.66 mm) (CNCR 36155), small springs in aquatic park Baño Grande, municipality of Mixquiahuala de Juárez, 20°14’41.63”N 99°12’18.62”W, 1914 m asl, coll. K.J. Madrigal, J.L. Villalobos & E. Moreno, 13 November 2021 ; 2 males (CL 12.81–15.78 mm, CW 21.36–26.69 mm), 4 females (CL 10.68–14.04 mm, CW 18.04–23.27 mm) (CNCR 361550), spring in Ventoquipa, municipality of Santiago Tulantepec de Lugo, 20°02’03.99”N 98°20’17.06”W, 2204 m asl, coll. E. Moreno, K.J. Madrigal & J.L. Villalobos, 12 November 2021 .

Redescription. Carapace slightly convex in dorsal view; surface finely punctuated/reticulated, punctuation grouped between postfrontal lobes and frontal border (Fig. 4B). Superior frontal border absent; front gently curved downwards; frontal border bilobed, continuous, slender, slightly punctuated laterally, giving crenated appearance, central portion with shallow, narrow depression (Fig. 4A, B). Postfrontal lobes visible, faintly elevated; frontal median groove poorly defined, wide; cervical grooves gently marked, straight, shallow, not reaching anterolateral margin (Fig. 4B). Gastric region well defined, convex, slightly higher than branchial region; cardiac region marked by 3 well delineated depressions, 2 near urogastric area, 1 close to intestinal region; urogastric sutures Y-shaped, horizontally disposed, middle faintly curved, elongated. External orbital angle without notch (Fig. 4B).Anterolateral margin ornamented with low granules, most conspicuous in meso-branchial section, decreasing progressively in size towards orbital external angle; posterior margin straight (Fig. 4B).

Frontal border inclined towards central portion in frontal view, convex at level of antennular fossae, without widening in lateral angle (Fig. 4A). Orbits subquadrangular; inferior orbital margin gently crenated, horizontally displayed; external orbital angle subacute; internal orbital tooth subtriangular, like grooved plate, separated from lateral angle of frontal border, leaving wide hiatus (Fig. 4A). Antennae not separated from front; antennal basal article not covered by lateral angle of frontal border (Fig. 4A). Interantennular septum small, sharp, inserted under frontal border. Operculum of antennal gland ovoid, with tuft of bristles on external portion. Efferent channel aperture rectangular, its width/length ratio 1.92. Epistomal tooth at septum level, triangular, downwards directed, apex slightly projected anteriorly (Fig. 4A). Pterygostomial region and epistome pubescent. Third maxillipeds completely cover buccal cavity; ischium of third maxilliped subtrapezoidal, width/length ratio 0.89, gnathal margin ornamented with small triangular teeth decreasing progressively in size distally, bristle tufts between teeth; merus of third maxilliped with anterolateral border rounded, does not extend beyond buccal cavity, width/length ratio 1.25; anterior notch present, well defined; gnathal border gently excavated to permit palp insertion, inferior portion ornamented with small teeth and long bristles; palp mesially pubescent, denser towards dactylus; third maxilliped surface punctuated, each punctuation with setae, distributed along gnathal margin; exognath wider at base, ending in acute apex, exognath/ischium length ratio 0.83 (Fig. 4C).

Chelipeds asymmetrical. Internal border of merus ornamented with small tubercles; carpus internal border granulated, small, rounded, with wide granules, distal portion armed with triangular spine, wide, with rounded apex. Major chela with palm surface punctuated; dactylus and fixed finger separated by broad gap; dactylus slender, slightly incurved; cutting borders dentated (Fig. 4D).

G1 straight, robust, distal third twisted towards median axis of sternal surface of body. In caudal view, distal third straight; distal crest of caudo-marginal projection higher than lateral crest; distal end of caudal surface with broad concavity, moderately deep (Fig. 4G). Caudal surface of mesial process with basal lobe rounded, poorly developed. In mesial view, caudo-marginal projection with subapical surface of caudal margin slightly excavated; crest of distal lobe smooth, widely rounded; distal lobe small, triangular, gently directed downwards, apex subacute, ornamented at tip with thin spine, acute and inconspicuous, separated from proximal lobe by V-shaped notch; proximal lobe U-shaped, elongated, length/width ratio 1.85, directed proximally, cephalic margin smooth, acutely curved distally (Fig. 4H). In cephalic view, distal third straight; distal and proximal lobes of caudo-marginal projection not disposed in the same plane, former one slightly mesially directed, latter one with inner surface moderately swollen, with raised median carina reaching middle portion (Fig. 4F). Mesial process subtriangular, perpendicular to G1 principal axis, ending laterally in acute spine; superior border with sinusoidal short distal crest, rising in middle portion, extending to inner lobe; inferior border convex, ending in lateral spine; inner lobe subtriangular, subacute, in contact with inner surface of proximal lobe (Fig. 4F). In lateral view, mesial process slightly projected caudo-laterally (Fig. 4I). In distal view, apical cavity U-shaped; widening cephalad; central crest of apical cavity subtriangular, deep, broad, ending well before reaching inner lobe of mesial process; apical spines field deep, adjacent to inner surface of lateral crest, with approximately 27 moderately long spines, disposed in 3–4 irregular caudo-cephalic rows, cephalic spines partially covered by superior border of mesial process (Fig. 4E). Aperture of spermatic channel in caudal position. Mesial process with lateral spine proximally broadened, distally straight, narrowing towards tip, faintly directed latero-caudally; basal lobe of caudal surface scarcely noticeable, rounded, poorly developed (Fig. 4E.)

Type locality. El Ojito Spring, pool in San Luis Apizaquito town, municipality of Apizaco, Tlaxcala, Mexico (see Discussion, Table 5).

Remarks. The general morphological pattern of this species is constant throughout its distribution range. Nevertheless, some variations were found in the opening of the efferent branchial channel (subquadrangular to subrectangular), the elevation of the gastric region relative to the branchial region and a different degree of development of the internal orbital tooth. The differences in the G1 comprise the different inclination of the distal third in cephalic view; the extension of the inner lobe of mesial process, that could stay in touch or not with the inner surface of the proximal lobe of the caudo-marginal projection; the presence of the small serration on the border of the distal lobe of the caudo-marginal projection is more evident in the population of San Miguel La Presa and absent in other localities; and the variation in the size of the basal lobe of the caudal surface of the mesial process. However, all these variations are not consistent with any geographic or population pattern, thus they may be representing the natural specific variation.

Distribution. Pseudothelphusa americana s. s. is distributed in Mexico along the central portion of the TVB in the states of Hidalgo, Puebla, and Tlaxcala (Villalobos-Hiriart, 2005). This species has been collected in springs, streams, and rivers. The localities in Michac in Puebla, as well as San Miguel La Presa, Amaxac de Guerrero, Apizaco and La Ascención Huitzcolotepec in Tlaxcala, are new records.