Pseudothelphusinae Ortmann 1893

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 : 176-188

Subfamily Pseudothelphusinae Ortmann 1893

Diagnosis (modified from Álvarez et al. 2020). Anterolateral margin often finely serrate or granulated to unarmed, lateral armature indistinct. Exopod of third maxilliped always more than half of ischium length, ratio exopod/ischium length ranging between 0.50 and 0.84. Branchial efferent channel without spine or tooth next to aperture; orifice of efferent channel open, gap between jugal and lateral angles. Gonopod slender to robust, with obvious torsion towards median axis of body. Marginal plate and caudal surface fused to end apically in caudo-marginal projection, directed cephalically with one to three lobes. Lateral lobes along main axis absent, except in Ehecatusa , Xoconochcothelphusa n. gen. and Spirothelphusa (see diagnosis of those genera), the latter one with a wide rounded lobe on distal half of principal axis and one accessory subapical spine on the caudolateral border ( Figs. 3 , 5 , 7 ). Mesodistal lobe can be present ( Tehuana ). Mesial process as triangular, subrectangular or as irregular plate or ax-shaped laminar expansion, commonly in longitudinal position relative to principal axis of gonopod and closing the apical cavity, rarely reduced (some species of Tehuana ). Apical cavity oblique or transversal to principal axis of gonopod, u-shaped ( Alvarezius , Mokayathelphusa , Pseudothelphusa , Smalleyus , Tehuana ), closed cephalically by internal angle of mesial process, or rounded ( Disparithelphusa , Ehecatusa ), or elongated and narrow ( Spirothelphusa , Xoconochcothelphusa n. gen.); field of spines distally located, irregularly disposed, with variable number of terminal-pore setae; opening of spermatic channel in caudal position, median crest present or absent.

Type genus. Pseudothelphusa de Saussure, 1857 .

Genera included. Alvarezius Moreno & Villalobos , in Moreno, Villalobos & Álvarez, 2022b; Disparithelphusa Smalley & Adkison, 1984 ; Ehecatusa Ng & Low, 2010 ; Mokayathelphusa Moreno, Villalobos & Álvarez, 2022b ; Pseudothelphusa de Saussure, 1857 ; Smalleyus Alvarez, 1989 ; Spirothelphusa Pretzmann, 1965 ; Tehuana Rodríguez & Smalley , in Smalley, 1970, and Xoconochcothelphusa n. gen.

Remarks. The subfamily Pseudothelphusinae is distributed exclusively in Mexico. The genus Pseudothelphusa , occupies a large area in Mexico, along the Pacific slope from the southern of Sonora, which is the northernmost limit of the superfamily Pseudothelphusoidea , to the south reaching coastal rivers of Oaxaca; in the central portion of the country, it extends its presence through the Transmexican Volcanic Belt from the west in Nayarit to the east in Puebla, with one extra record of P. parabelliana Alvarez 1989 , in Los Tuxtlas region in Veracruz. The other eight genera in the subfamily occur in southern Mexico, in the states of Veracruz, Oaxaca, Tabasco and Chiapas, in the latter one a new region is added that includes the Pacific slope from the town of Tonalá, to the border with Guatemala, known as the Soconusco region, which is the distribution area of Xoconochcothelphusa chiapensis n. comb.

Key to the genera of the subfamily Pseudothelphusinae Ortmann, 1897

1. Apex of the G1 with lateral process...................................................................... 2

- Apex of the G1 without lateral process.................................................................... 4

2. G1 with caudolateral border of principal axis bearing a wide subcircular laminar plate or reduced to a crenate crest on distal half................................................................................................ 3

- G1 with caudolateral border of principal axis smooth, without any additional ornamentation; apex with the mesial and lateral processes fused, forming an apical plate with three triangular lobules, in transversal position and distally extended beyond the apical cavity............ Xoconochcothephusa n. gen. (one species: X. chiapensis ( Rodríguez & Smalley, 1972) n. comb.)

3. G1 principal axis ornamented on the distal half of caudolateral border with a crenate crest, divided in 11 subtriangular teeth; apical cavity subcircular, as a shallow funnel; caudo-marginal projection ending apically in a slender, rectangular distal lobe (3.2 × as wide as long), which is cephalad directed and extended in front of the distal portion of mesial process, with its superior and inferior borders straight, and the cephalic end rounded........................................................................................ Ehecatusa (one species: E. mixtepensis (Rodríguez & Smalley, in Smalley, 1970))

- G1 principal axis ornamented on the distal half of caudolateral border with a wide subcircular laminar plate, with some irregular, sharp edge; apical cavity narrow, widening to cephalic portion; caudo-marginal projection ending apically in a prominent oval lobe, which is twisted around the gonopod cephalic surface, its margin is serrated with small spinules....................................................................... Spirothelphusa (one species: S. verticalis ( Rathbun, 1893))

4. G1 apex ornamented with spines; caudo-marginal projection single-lobed and finished cephalically in a border armed with spines or acute indentation.................................. Smalleyus (one species: Sm. tricristatus Alvarez, 1987 )

- G1 apex smooth without spines or ornamented with small spinules on the distal crests or on the inner faces of caudal, caudo-marginal and lateral surfaces of the apical cavity; caudo-marginal projection ending cephalad in 1-3 lobes, the distal one may be absent or appear as an acute, triangular, or rounded tooth................................................... 5

5. Distal conical prominence emerging from lateral crest, bearing apical setae; caudo-marginal projection single-lobed, lobe axe-shaped, large, about half of G1 length, cephalic border smooth, spinulated on the fusion with distal crest; mesial process as a subtriangular plate, tapering laterally, ending in two tips...................................................................................... Alvarezius (one species: Alvarezius zongolicae ( Alvarez, Villalobos & Moreno, 2012))

- Distal conical prominence on lateral crest absent; caudo-marginal projection uni, bi or tri-lobed, proximal lobe when present frequently axe-shaped; mesial process as a rectangular, subtriangular, or irregular plate, lateral margin ending in 1–2 spines, or in a different number of triangular teeth................................................................... 6

6. Mesodistal prominence present, conical or compressed caudo-cephalically; internal surface of proximal lobe of caudo-marginal projection with a high and well-marked carina; principal axis of G1 with the lateral constriction at mid-length................................................................................................ Tehuana (10 species)

- Mesodistal prominence absent; internal surface of proximal lobe of caudo-marginal projection with a softly or moderated marked carina; principal axis of the G1, with the lateral constriction on the distal third of his length................... 7

7. Caudo-marginal projection uni or bilobed, small triangular-shaped distal lobe, with an acute cephalic end (rarely rounded), or transformed into a row of denticles; may be separated from the proximal lobe by a V- or U-shaped notch, or may simply protrude from the superior angle of the proximal lobe; proximal lobe elongated or suboval (wider than long), and with the inner surface smooth or armed with a smooth to moderate straight carina; mesial process in the form of a triangular or subrectangular blade, terminating laterally in a long sharp spine or two or more teeth or denticles, and mesially usually with a small subtriangular expansion that closes the cavity of the gonopod apex.................................. Pseudothelphusa (27 species)

- Caudo-marginal projection trilobed, distal and middle lobes triangular and rounded or spiniform of same length, without V- or U-shaped notch, and simply protrude from the superior angle of the proximal lobe; proximal lobe ax-shaped, elongated and straight, or as slender sheet, curved, extending through distal third of main gonopod axis; mesial process large, subrectangular with lateral margin ornamented with several spiniform teeth or moderately small and triangular....................... 8

8. Caudo-marginal projection trilobed, distal and middle lobes triangular and rounded, respectively, proximal as elongated and straight lobe, ax-shaped; mesial process moderately small and triangular, lateral margin ended in an acute spine, internal angle projected above the inner surface of proximal lobe of caudo-marginal projection, as a triangular plate apically subacute; apical cavity with the central crest rounded, armed on the surface and internal faces of the apical cavity with numerous spinules and short setae..................................... Disparithelphusa (one species: D. pecki Smalley & Adkison, 1987 )

- Caudo-marginal projection trilobed, distal and middle lobes spiniform of same length, proximal as elongated and curved sheet extending through distal third of main gonopod axis; mesial process large, subrectangular, with lateral margin ornamented with several spiniform teeth; apical cavity with the central crest rounded in the portion adjacent to spermatic pore and straight towards the internal angle of mesial process, with his surface smooth; corneous setae present in the field of spines area and on the internal surface of the cavity caudal portion............................................................................................. Mokayathelphusa (one species: M. angelsotoi Moreno, Villalobos & Álvarez, 2022b )

Figures

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.

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 7. Spirothelphusa verticalis Rathbun, 1893, male (cl 20.7 mm, cw 33.2 mm) (CNCR 25444), distal portion of left G1. A, mesial view; B, cephalic view; C, lateral view; D, caudal view; E, distal view. Abbreviations: Ac = apical cavity; Apls = apical plate of lateral surface; Asus = accessory subapical spine; Cmp = caudo-marginal projection; Dlcmp = distal lobe of caudo-marginal projection; Las = lateral suture; Llopa = lateral lobe of principal axis; Map = marginal plate; Mas = marginal suture; Mep = mesial process.