Ehecatusa Ng & Low, 2010

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 : 177-178

Ehecatusa Ng & Low, 2010

Epithelphusa Rodríguez & Smalley , in Smalley, 1970: 103 (list), 105 (key).— Pretzmann 1972: 109.— Pretzmann 1974: 297.— Rodríguez & Smalley 1972: 75-76.— Rodriguez 1982: 126.— Villalobos-Hiriart et al. 1993: 287 (list).— Villalobos-Hiriart 2005: 2, 3 (tabla 1), 4, 7, 8, 10, 14-15, 17, 22, 51-53, 58, 59, 85, 87-89, 96, 105, 175, 181, 183.—Villalobos-Hiriart & Álvarez 2008: 248 (tabla 1), 284, 299 (list).— Ng et al. 2008: 173 (list).— Villalobos & Alvarez 2010: 466 , 471, 472.— Ojeda-Escoto 2017: 8, 10, 11.

Ehecatusa Ng & Low, 2010: 35 [ nom. nov. for Epithelphusa Rodríguez & Smalley , in Smalley, 1970].— Guinot & Hendrickx 2014: 478 (table 1).— Alvarez & Villalobos 2016: 243.— Ojeda-Escoto 2017: 10, 11, 16, 26 (fig.), 27, 40 (fig.), 41 (tabla 2.2), 90–91 (apéndice 2).— Villalobos-Hiriart et al. 2019: 156 (table 1).— Álvarez et al. 2020: 12 (table 4), 20, supplementary material (table 1).— Moreno-Juárez et al. 2022a: 2.

Diagnosis. Carapace with dorsal surface slightly convex; posterior to cervical grooves with scattered short black bristles; cervical and mid frontal grooves wide, shallow, but marked; frontal portion regularly curved downward, to reach inferior frontal margin; superior frontal margin absent; lateral margin rounded and smooth. Orbits with internal inferior tooth, forming slender, grooved plate, slightly curved up, leaving orbital hiatus open, lodging antennal peduncle ( Fig. 2 ). Exopod of third maxilliped shorter than ischium lateral border (0.72 × its length). G1 straight, somewhat slender, with distal third twisted towards median axis of sternal surface of body; caudolateral border with crenate crest on distal half of principal axis, and two subapical prominences, distal one forming part of apical cavity border. In mesial view, marginal plate and caudal surface fused on distal third to form caudo-marginal projection ending apically in slender rectangular lobe (3.2 × as wide as long) cephalad directed and lying over distal portion of mesial process, with its superior and inferior borders straight; cephalic end rounded ( Fig. 3A ). Mesial process in form of large, ax-shaped plate, cephalad directed, proximally elongated, with cephalic border straight through superior half and widely rounded along inferior one to reach caudal border; this border straight, slightly serrated and parallel regarding principal axis of G1. Marginal suture straight and evident along principal axis. Horns of lateral process slightly perceptible between principal axis and mesial process. In cephalic view, principal axis straight, lobe of caudo-marginal projection narrow, extending cephalically close to distal portion of mesial process and with final third curved mesially, separated from mesial plate ( Fig. 3B ). Mesial process as laminate plate, cephalic border entire and regularly curved in proximal third; superior border slightly concave. Lateral process formed by two conical spines, like vertical horns laterally directed; proximal spine larger than distal; space between them somewhat convex; distal spine forming part of border of apical cavity. Principal axis with crenate crest on distal half of caudolateral border evident and armed with 11 subtriangular teeth. In lateral view, distal half of principal axis slightly inclined laterally; mesial process as big ax-shaped plate, proximally elongated, with cephalic border widely and slightly curved, reaching caudal border; this border straight and parallel regarding principal axis of gonopod ( Fig. 3C ). Lateral process formed by two conical spines in vertical position; proximal spine conical, acute, and larger than distal; space between them with short and sharp medial border; distal spine forming part of border of apical cavity, with rounded and excavated apex. Caudolateral border of principal axis with crenate crest on distal half armed with 11 subtriangular teeth, and two accessory prominences, the distal one as elongate spoon, incurved, forming part of caudal portion of crest delimiting apical cavity; subdistal cylindrical, smooth, with acute apex. Apical cavity partially visible, with scattered setae on surface. In caudal view, distal half of principal axis straight, distal crest delimiting apical cavity concave, rising by distal prominence of caudolateral border ( Fig. 3D ). Cephalic portion of apical cavity and field of setae noticeable; central crest of apical cavity, straight and thin, delimiting field of setae. Caudolateral border with crenate crest on distal half with 11 subtriangular teeth; distal accessory prominence as elongate spoon, incurved, forming part of crest delimiting apical cavity; subdistal prominence cylindrical, smooth, with acute apex. Lateral process formed by two vertical horns, proximal spine larger, conical and acute; distal one shorter and triangular, continuing from apex cavity and laterally directed. In distal view, apical cavity subcircular, like shallow funnel, delimited by distal crests of apical lobe of caudo-marginal projection, caudal surface, distal prominences of caudolateral border and lateral process, mesial surface, and central crest; central crest as an internal extension of distal crest of mesial process ( Fig. 3E ). Setae field with short setae and conical granules, narrowly disseminated around opening of spermatic channel; spermatic channel in caudomesial position.

Type species. Epithelphusa mixtepensis Rodríguez & Smalley , in Smalley, 1970, by original designation.

Species included. Ehecatusa mixtepensis (Rodríguez & Smalley, in Smalley, 1970).

Distribution. This monotypic genus is known only from the type locality of Eh. mixtepensis at 36 km N of San Gabriel Mixtepec (approximately 16°20’42.19”N, 97°05’21.61”W; 858 m asl), municipality of San Gabriel Mixtepec, Oaxaca, Mexico.

Remarks. Ehecatusa , a replacement name for Epithelphusa Rodríguez & Smalley , in Smalley, 1970, belongs to a group of genera, each with one or two species, with a complex G1 morphology. Morphologically, Ehecatusa belongs to the subfamily Pseudothelphusinae because the G1 has a caudo-marginal projection that distally ends in a slender lobe, extended cephalad. It can be distinguished from the other genera of Pseudothelphusinae by the presence of the lateral process, which is formed by two curved spines, like vertical horns; and by the unique form of the mesial process, which is a large, ax-shaped plate, cephalad directed, and proximally elongated. Also, the genetic analysis of the genus Ehecatusa shows that it is sister clade to all the genera of the former Pseudothelphusini tribe, after genus Smalleyus Alvarez, 1987 ( Fig. 1 ).

Figures

FIGURE 1. Tree obtained from the concatenated analysis of H3, 16S and COI through Maximum Likelihood and Inference Bayesian. Each color represents the subfamilies recognized by Álvarez et al. (2020): red—Ptychophallinae; green— Potamocarcininae;yellow—Raddausinaeandpurple—Pseudothelphusinae.The lineagesof EhecatusaandXoconochcothelphusa genera were colored with blue.Values at nodes represent bootstrap values for the Maximum Likelihood analysis (above branches, scores 1–100) and posterior probabilities (below branches, scores 0-1).

FIGURE 2. Ehecatusa mixtepensis (Rodríguez & Smalley, in Smalley, 1970), male holotype (cl 16.8 mm, cw 26.9 mm) (CNCR 309). A, carapace dorsal view; B, carapace frontal view; C, major chela.

FIGURE 3. Ehecatusa mixtepensis (Rodríguez & Smalley, in Smalley, 1970), male holotype (cl 16.8 mm, cw 26.9 mm) (CNCR 309), distal portion of left G1. A, mesial view; B, cephalic view; C, lateral view; D, caudal view; E, distal view. Abbreviations: Ac = apical cavity; Apclb = accessory prominences of caudolateral border; Ccac = central crest apical cavity; Ccclb = crenate crest of caudo-lateral border; Cmp = caudo-marginal projection; Cslp = conical spines of lateral process; Dlcmp = distal lobe of caudo-marginal projection; Map = marginal plate; Mas = marginal suture; Mep = mesial process; Sfac = setae field of apical cavity; Spch = spermatic channel.