Pseudothelphusa purhepecha Ojeda-Escoto, Villalobos & Álvarez, 2017, n. sp.
Creators: name: Ojeda-Escoto, Juan Carlos
name: Villalobos, José Luis
name: Álvarez, Fernando
Publisher: name: Zenodo
Year: 2017
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Decapoda
Pseudothelphusidae
Pseudothelphusa
Pseudothelphusa purhepecha

description: Pseudothelphusa purhepecha n. sp.
(Figs. 6, 7)
Pseudothelphusa (Pseudothelphusa) dugesi belliana Rodríguez & Smalley, 1969: 81 fig. 13, pl. 9. Pseudothelphusa belliana Rodríguez, 1982: 135, fig. 88. García-Madrigal & Bastida-Zavala, 1999: 921. Pseudothelphusa belliana form Agua Blanca Villalobos, 2005: 306, pl. 16.
Type material. Male holotype, cl 21.9 mm, cb 36.7 mm; 1 female allotype cl 26.0 mm, cb 41.9 mm; El Serpentín in San José Purúa (19°29' N, 100°29' W; 1,900 m asl), Municipality of Jungapeo, Michoacán, Mexico; 1 January 1957; coll. A. Padilla; CNCR 31746. 4 male paratypes, cl 11.4–17.3 mm, cb 17.3–27.9 mm; 4 female paratypes, cl 15.5–24.9 mm, cb 24.4–41.5 mm, same locality, date and collector as holotype; CNCR 31747. All of these individuals, the holotype, allotype, and paratypes, were considered as Pseudothelphusa dugesi belliana and included as part of the material examined by Rodríguez & Smalley (1969: 81, fig. 13a–e), catalog number UNAM 4 25 61.
Other material examined. 7 males, cl 13.2–15.0 mm, cb 21.0– 24.2 mm; 11 females, cl 12.4–18.3 mm, cb 19.3–29.2 mm; Agua Blanca (18°57' N, 103°19' W; 500 m asl), Municipality of Coalcomán de Vázquez Pallares, Michoacán, Mexico; 5 July 1986; coll. O. Meade; CNCR 5871. 2 males, cl 20.0, 24.6 mm, cb 32.4, 41.2 mm; 2 females, cl 18.0, 19.8 mm, cb 29.0, 33.7 mm; same locality and date as CNCR 5871; colls. R. Lamothe and L.J. Rangel; CNCR 8362. 2 males, cl 20.0, 24.0 mm, cb 32.4, 41.0 mm; 2 females, cl 18.0, 19.8 mm, cb 29.0, 33.7 mm; same locality as 5871; without collection date; coll. anonymous; CNCR 8816. 7 males, cl 10.8–20.7 mm, cb 16.3– 33.2 mm; 7 females, cl 8.3–19.6 mm, cb 11.7–31.9 mm; Tuxpan, near San José Purúa, Municipality of Zitácuaro, Michoacán, Mexico; 1–2 November 2004; coll. F. Álvarez; CNCR 27310.
Description. Dorsal surface of carapace smooth, puntacted, central portion flat (Fig. 6 A). Front without superior border, curved downward to reach inferior frontal border, visible in dorsal view (Fig. 6 D). Front smooth, faintly bilobed. Postfrontal lobes well formed, portion of carapace anterior to postfrontal lobes convex (Fig. 6 D). Median frontal groove shallow, well-marked, separating postfrontal lobes, becoming obsolete little after. Cervical grooves well marked, wide, straight, reaching anterolateral margins. Regions moderately indicated, gastric, branchial, intestinal swollen; cardiac depressed (Fig. 6 A). Anterolateral margin not prominent in lateral view, serrated, with blunt tubercles, 22–23 in males, 15–17 in females, from cervical groove to branchial region; area between orbit, cervical grove with 6–7 rounded granules. Posterior margin straight in males (Fig. 6 A), slightly concave in females.
External angle or orbit faintly developed, granulated, with shallow basal notch; internal angle inside orbital cavity with moderate keel. Antennal basal article, separated from anterior frontal margin by narrow hiatus (Fig. 6 D). In frontal view, antennules, antennular fossae concealed by front, in juveniles antennular fossae partially visible; ventrally, antennular fossae wider in middle, inferior frontal margin slightly sinuous; interantennular septum almost completely covered by carapace. Opercular plate of antennal gland ovoidal, with small middle constriction, tuft of setae on external third. Epistome, area surrounding buccal cavity with dense patch of setae; lateral portions with rounded granules; epistomal tooth small, triangular, granulated, with apex directed downwards at same level of interantennular septum, between third maxilliped palps when closing buccal cavity (Fig. 6 D). Opening of efferent branchial channel subquadrangular, ratio wide/length 1.19 (range 1.0 to 1.6; n= 40). Third maxilliped with ischium trapezoidal, slightly longer than wide; merus narrower than ischium, anterior margin rounded with shallow, rounded notch next to insertion of palp (Fig. 6 C); ratio exopod/ischium 0.66 (range 0.57 to 0.77; n= 40).
Chelipeds asymmetrical. Merus of larger cheliped with row of blunt tubercles along internal margin, carpus with strong triangular spine on internal margin. Internal surface of chela smooth, globose; fingers gaping, curved inward distally, with low, triangular teeth on cutting edges (Fig. 6 B). Dactylus rather narrow, widely curved, dorsally ornamented with several longitudinal rows of small pits, black granules.
Male gonopod moderately strong. In mesial view, distal crest of caudomarginal process curved, higher than lateral crest. Distal lobe of caudomarginal projection ending as triangular tooth, separated from mesial process by V-shaped notch, apex reaching beyond cephalic margin of proximal lobe. Proximal lobe longer than wide, reniform, proximally directed (Fig. 7 A). In cephalic view, distal lobe of caudomarginal projection directed cephalically, as proximal lobe; internal surface swollen, in contact with internal expansion of mesial process (Fig. 7 B). Proximal lobe parallel to principal axis of gonopod; internal surface swollen, cephalic margin straight. Mesial process as triangular laminar expansion; lateral margin ending in two teeth, latero-caudally directed; distal one small, subacute, proximal one larger, strong, acute. Superior border of process slightly concave, extending internally to close apical cavity cephalically, touching internal surface of caudomarginal projection; same border forming central crest of apical cavity to delimit field of spines (Fig. 7 B). Inferior border widely convex. In caudal view, caudal surface of mesial process smooth; distal crest widely concave; caudomarginal crest higher than lateral one (Fig. 7 D). In apical view, cavity U-shaped, opening of sperm channel in caudal position; field of spines wide, close to lateral crest, with about 50 terminal pore setae, some organized in central tuft; mesial surface armed with hook-shaped spines, caudal, lateral surfaces with spinules (Fig. 7 E).
Geographical distribution. Known from several localities in the state of Michoacán: Agua Blanca (19°30'04" N, 100°22'22" W; 1,690 m asl), Municipality of Zitácuaro; El Serpentín in San José Purúa (19°29' N, 100°29' W; 1,460 m asl), Municipality of Jungapeo; Río Frío (19°04'15" N, 101°25' W), Río San José (19°03'30" N, 101°26'01" W), and Río Guayabo (19°04'15" N, 101°26'53" W), Municipality of Turicato; Huiramba (19°32'13" N, 101°26' W), Municipality of Huiramba; 1 km from Tres Palos (18°59' N, 101°41' W), and 1 km from Carámicuas (19°02'40" N, 101°38'30" W), Municipality of Ario (García-Madrigal and Bastida-Zavala, 1999). These localities are all part of the Tuxpan River basin, interconnected by small tributaries. The region is characterized by an irregular topography formed principally by the Tuxpan shield and an important number of volcanic cones. The thermal springs in San José Purúa and Agua Blanca are inside aquatic parks, part of the Jungapeo geothermal system (Siebe et al. 2007).
Etymology. The species name is taken from P’urhepecha, the prehispanic native culture that developed and established through the highlands of NW Michoacán, it is used as a noun in apposition.
Remarks. Few variations were noted among the studied specimens. The shape and number of granules along the anterolateral margin of the carapace varied slightly (22–23 in males, 15–17 in females); the granules vary from rounded to subacute, the latter are more evident in females. The posterior margin of the carapace varies from straight in big adults to slightly concave in smaller crabs, both male and female. The distal tooth of the mesial process of the gonopod appears as a rounded granule in small males, changing to a well-developed tooth in large males.
The mesial process of the gonopod with two teeth on the lateral margin distinguishes the new species from the related Pseudothelphusa belliana (Rathbun, 1898: 515, fig. 4). Furthermore, this character relates the new species with P. nayaritae Álvarez & Villalobos, 1994, P. rechingeri Pretzmann, 1965, P. lophophallus Rathbun, 1898, and P. parabelliana Álvarez, 1989. It can be distinguished from all of them by the distal lobe of the caudo-marginal projection which is well formed in contrast to the reduction in size seen in P. parabelliana or the reduction to a series of small teeth seen in the other three species mentioned. The distribution of morphologically related species to P. purhepecha n. sp. does not reflect a close geographical distribution; P. nayaritae, P. rechingeri, and P. lophophallus are distributed the states of Nayarit, Durango and Sinaloa, whereas P. parabelliana occurs in the Los Tuxtlas region, Veracruz. Instead, P. purhepecha n. sp. is geographically close to P. dilatata, distributed in the Balsas River basin.
description: Published as part of Ojeda-Escoto, Juan Carlos, Villalobos, José Luis & Álvarez, Fernando, 2017, Three new species of freshwater crabs of the genus Pseudothelphusa (De Saussure, 1857) (Crustacea: Decapoda: Pseudothelphusidae) from Mexico, pp. 559-571 in Zootaxa 4216 (6) on pages 567-570, DOI: 10.5281/zenodo.242442