Xoconochcothelphusa chiapensis ( Rodríguez & Smalley, 1972 ) Villalobos-Hiriart & Moreno-Juárez & Álvarez, 2024

Villalobos-Hiriart, José Luis, Moreno-Juárez, Eric G. & Álvarez, Fernando, 2024, Xoconochcothelphusa, a new genus for Ehecatusa chiapensis (Rodríguez & Smalley, 1972), with notes on Spirothelphusa Pretzmann, 1965 (Crustacea: Decapoda: Pseudothelphusidae), Zootaxa 5523 (2), pp. 171-191 : 181-185

Xoconochcothelphusa chiapensis ( Rodríguez & Smalley, 1972) , n. comb.

( Figs. 4 , 5 , 6 )

Spirothelphusa chiapensis Rodríguez & Smalley, 1972: 75 , fig 6, pl.3.

Epithelhusa chiapensis .— Rodriguez 1982: 128, 129, fig. 83.— Villalobos-Figueroa 1982: 220 (list).— Magalhães 1987: 57 (fig. 5), 58.— Villalobos-Hiriart et al. 1993: 287 (list).— Álvarez & Villalobos 1995: 90.— Villalobos-Hiriart 2005: 3 (table 1), 8, 17, 22 (table 2), 26 (table 3), 43, 51, 52, 58, 152.—Villalobos- Hiriart & Álvarez 2008: 248 (tabla 1), 284, 299 (list);— Ng et al. 2008: 173 (list).— Villalobos & Álvarez 2010: 461 (table 1), 466, 471, 472.— Ojeda-Escoto 2017: 44.

Ehecatusa chiapensis .— Ng & Low 2010: 35.— Guinot & Hendrickx 2014: 478 (table 1).— Alvarez & Villalobos 2016: 252 (table 8.1).— Ojeda-Escoto 2017: 16, 27, 50, 64, 95 (apéndice 3).— Villalobos-Hiriart et al. 2019: 156 (list).— Álvarez et al. 2020: 21, 23 (key)

Material examined. Holotype: male, cl 15.3 mm, cw 26.5 mm ( CNCR 310 ) Finca Victoria (15°28’79.50”N, 92°42’14.89”W; 988 m asl), Municipality of Motozintla, Chiapas, Mexico, coll. Anonymous, 2 April 1962 . Paratypes: male, cl 15.5 mm, cw 25.8 mm; same catalog number, locality, collector, and date as holotype; male, cl 20.0 mm, cw 32.5 mm ( CNCR 34841 ), stream tributary of Vado Ancho River (15°22’58.78”N, 92°35’05.20”W; 365 m asl), approximately 10 km NE of Escuintla , Municipality of Escuintla, Chiapas, Mexico, coll. Angel Soto, July 2018 .

Description. Moderate sized crab (cl 15.3–20.0 mm; cw 25.8–32.5 mm). In dorsal view, carapace transversally oval, widest anteriorly, dorsal surface flat, smooth, regions faintly indicated, gastric and branchial inflated, separated by wide, straight, shallow cervical groove, narrowing towards anterolateral margin of carapace, and disappearing well before reaching it ( Fig. 4A ). Frontal region punctate, depressed with respect to carapace surface. Postfrontal lobes low, slightly distinct, anteriorly marked by light depressions, separated by narrow, shallow median groove, anteriorly forming V-shaped notch dividing straight superior frontal margin, fading posteriorly. Pair of gastric furrows on metagastric region, approximately straight, divergent, forming wide V. Lateral margins of carapace sharp, finely serrated, posterior half smooth; portion between external orbital tooth and cervical groove straight, smooth. Posterior margin of carapace convex. In frontal view, front vertically deflexed, smooth, bilobed; inferior frontal border granulated, projected, slightly concave in middle; superior frontal border bilobed, lobes defined by low, rounded granules, irregularly disposed, separated by mesial notch ( Fig. 4B ). Superior margin of orbit granulated, continuous with inferior frontal border; lower orbital margin marked by row of granules; exorbital angle smooth; internal inferior tooth, triangular, moderately high; orbital hiatus, occupied by basal segment of antennal peduncle. Medium septum dividing antennular fossae sharp, concealed by inferior frontal border. Epistomal space with setae, margin with median, triangular tooth; tip acutely rounded, separated of lateral ones by wide, rounded notches with granulated borders. Orifice of efferent branchial channel open, quadrangular, jugal and lateral angles gaping. Pterygostomial area hairy, faintly granulated. Ratio of exopod/ischium of third maxilliped 0.9.

First pereopods distinctly heterochelous, robust; major chela right. Larger cheliped with merus subtriangular in cross section; inner border sharp with conical granules, outer margin rounded, armed with low granules; inferior surface smooth. Carpus surface smooth, internal border armed with row of conical tubercles, ending anteriorly in small conical spine. Palm moderately swollen, smooth. Fingers with longitudinal rows of punctations, some of them black on distal half; slightly curved inwards, leaving narrow gap, tips crossing, bearing triangular sharp teeth on cutting edges. Dactyl slender, tip abruptly curved downwards, with longitudinal rows of low, rounded granules on dorsal surface; proximal half of cutting edge with three large teeth, rest decreasing in size distally. Propodus slightly more robust, punctate, cutting edge with alternate large-small triangular teeth, proximal tooth slender, large, followed by two smaller ones; remaining teeth triangular decreasing in size distally ( Fig. 4C ). Smaller cheliped moderately slender; merus internal surface smooth, superior border tuberculate, inferior one granulated; palm smooth, inferior surface delicately granulated; chela with fingers gently curved inwards, closing completely, cutting edges armed with triangular teeth, tips crossing; dactyl with dorsal surface punctated; cutting edge of propodus with alternate large and small sized teeth.

Ambulatory pereopods normal, decreasing in length posteriorly; ischia, meri, carpi and propodi smooth; dactyli slender, slightly longer than propodus, bearing 4-5 longitudinal rows of small, sharp, corneous spinules. Ventral surface of carapace smooth, sternal sutures discernible; first sternite triangular, second to fourth fused, fifth to eight well marked. Abdomen triangular, all somites free, third somite broadest, sixth longest. Telson triangular, proximal margin slightly sinuous, lateral margins straight, apex subacutely rounded.

G1 as in diagnosis of the genus.

Remarks. The specimen CNCR 34841, collected near the town of Escuintla, Chiapas, extends the distribution of X. chiapensis n. comb. approximately 20 km to the northwest, from Finca Victoria, near the Guatemalan border. This specimen is slightly bigger than the holotype and presents some differences in the G1 morphology, mainly in the size of the caudo-marginal plate, which is shorter, not as wide, and the inferior margin presents only one indentation. This rare species is known from only four males (one of them deposited in the Museu de Zoologia da Universidade de São Paulo, MZUSP 6380 (see Magalhães 1987)), therefore, it is difficult to assess the degree of variation in the G1 and other structures.

Figures

FIGURE 4. Xoconochcothelpusa chiapensis (Rodríguez & Smalley, 1972) n. comb., male holotype (cl 15.3 mm, cw 26.5 mm) (CNCR 310). A, carapace, dorsal view; B carapace, frontal view; C, major chela.

FIGURE 5. Xoconochcothelphusa chiapensis (Rodríguez & Smalley, 1972) n. comb., male holotype (cl 15.3 mm, cw 26.5 mm) (CNCR 310), distal portion of left G1. A, mesial view; B, cephalic view; C, lateral view; D, caudal view; E, distal view. Abbreviations: Ac = apical cavity; Ccac = central crest apical cavity; Cmp = caudo-marginal projection; Cs = caudal surface; Dccs = distal crest of caudal surface; Dlcmp = distal lobe of caudo-marginal projection; Lp = lateral process; Lsh = lateral shoulder; Map = marginal plate; Mas = marginal suture; Mep = mesial process; Sf = spine field of apical cavity; Spch = spermatic channel.

FIGURE 6. Xoconochcothelphusa chiapensis (Rodríguez & Smalley, 1972) n. comb., male holotype (cl 15.3 mm, cw 26.5 mm) (CNCR 310), total view of left G1. A, mesial view; B, cephalic view; C, lateral view; D, caudal view. Abbreviations: Fsmap = fringe setae marginal plate; Las = lateral suture; Map = marginal plate; Mas = marginal suture.