Potamocarcinus armatus H. Milne Edwards, 1853

Magalhães, Célio & Wehrtmann, Ingo S., 2025, Taxonomic revision and distribution of the freshwater crabs of the family Pseudothelphusidae (Decapoda, Brachyura) from Guatemala, with the descriptions of two new species and keys to the species of all genera, Zoosystema 47 (26), pp. 581-615 : 583-585

Potamocarcinus armatus H. Milne Edwards, 1853

( Figs 1; 13)

Potamocarcinus armatus H. Milne Edwards, 1853: 208 ; 1854: 174, pl. 13, fig. 3. — Rathbun 1905: 308 (part). — Villalobos Hiriart & Álvarez 2008: 297 (part, in list). — Ng et al. 2008: 176 (part, in list). — Wehrtmann et al. 2016: 779 (in list). — Acevedo-Alonso & Cumberlidge 2022: 582 (Appendix 2, in list).

Potamocarcinus ( Potamocarcinus) armatus – Bott 1967: 374. — Pretzmann 1971: 20 (in list). — Rodríguez 1982: 119, figs 69g, 70a, h, 71c.

Potamocarcinus ( Potamocarcinus) nicaraguensis aequispinosus Pretzmann, 1971: 20 ; 1972: 69, figs 385, 386, 408, 409.

Potamocarcinus ( Potamocarcinus) armatus aequispinosus – Pretzmann 1975: 617, pl. 2, pl. 6 figs 18, 19; 1980: 655, pl. 15 fig. 64.

TYPE MATERIAL EXAMINED. — Holotype (by monotypy). Guatemala • 1 ♀ (60.1:40.5), dry; collecting data unknown; MNHN-IU-2000-4025 (= MNHN-B4025 ) .

OTHER MATERIAL EXAMINED. — Guatemala • 1 ♂ 4♀; Petén, Laguna de Petén , outlet; [ 16°58’40.75”N, 89°42’04.80”W; 113 m elev.]; 20.II.1935; H. van der Schalie leg.; USNM 189301 • 1 juv. ♂ (17.3:11.8) 4 ♀ (20.3:14.4-32.6:22.0); Petén, Lago Petén-Itzá, northern portion ; 16°59’48”N, 89°42’10”W; 122 m. elev.; 14.I.2014; I. S. Wehrtmann & M. Orozco leg.; UCR-MZ 3234 • 2 ♂, 2♀; Petén, Río Subín, Subín ; 16°38’14”N, 90°10’59”W; 115 m. elev.; 15.I.2014; I. S. Wehrtmann & M. Orozco leg.; UCR-MZ 3235 • 2♂ (33.2:21.7; 41.5:25.9), 1♀ (36.3:24.0); Petén, Río Subín, Subín ; 16°38’14”N, 90°10’59”W; 115 m. elev.; 15.I.2014; I. S. Wehrtmann & M. Orozco leg.; INPA 2123 • 1♂ (36.5:23.7) 2 ♀; Alta Verapaz, Río Chajmayic [= Chajmaic] [ 15°45’05”N, 89°56’45”W; 197 m elev.], about midway between Río San Simón and Celba ; 14.IV.1935; C. L. Huffs et al. leg.; USNM 230095 .

DISTRIBUTION. — Guatemala ( Alta Verapaz, Petén) ( Pretzmann 1980, Wehrtmann et al. 2016; this study) ( Fig. 13).

OTHER RECORDS IN GUATEMALA. — Pretzmann (1980): Petén, Laguna Petén-Itzá, Flores [ 16°55’39”N, 89°54’10”W; 112 m elev.]; Petén, road to Belize, near Macanché [ 16°57’39”N, 89°38’02”W; 193 m elev.]; Petén, Mopan, at Río Melchor Mencos, border with Belize [ 17°03’27”N, 89°09’06”W; 92 m elev.].

DESCRIPTION OF G1 ( Fig. 1 G-I)

Stout, straight in both caudal, mesial views, moderately compressed mesolaterally; caudal margin nearly straight; lateral margin straight proximally, distinctly concave distally in mesial view; mesial surface with irregular rows of minute setae medially; caudal surface with elongated patch of caudal setae along proximal and median portions, setae longer proximally, decreasing in size medianly; mesocephalic surface with subdistal, elongated patch of setae slightly increasing in size distally. Spermatic channel distal opening on apex cavity, situated towards lateral end at base of caudal process. Marginal suture on mesial surface, straight along most of stem, regularly curved to lateral side distally in mesial view, proximal portion with row of large marginal setae. Marginal process subtriangular, erect, tip slightly rounded, as long as or slightly longer than caudal process in mesial and laterocephalic views, partially overlapping caudal process. Lateral suture incomplete, marked by somewhat deep sulcus on first 3/4 of caudal surface. Mesial process as strong subtriangular projection directed cephalad on distal portion of mesocephalic surface. Apex slightly distorted in cephalic direction; caudal process erect (not folded over apex cavity), largely projected distally, tip rounded in mesial, laterocephalic views. Apex cavity short; field of apical spines weakly developed, with few short, small spines slightly extended distally along half length of cephalic surface of caudal process. Cephalic process vestigial, reduced to two low protuberances subapically on cephalic surface at base of mesial process.

REMARKS

The type locality of this species is unknown (H. Milne Edwards 1853). The holotype of Po. ( Po.) nicaraguensis aequispinosus Pretzmann, 1971 , a junior synonym of Po. armatus , is a female (NHMB 550a – not examined) from an unknown locality in Guatemala. For the discussion of the taxonomic status and type locality issues regarding these taxa, see Rodríguez (1982: 120).

The presumptive occurrence of this species in Mexico was based on specimens from Río Macuspana (Monte Cristo, municipality of Macuspana, state of Tabasco) identified by Rathbun (1905) and Rodríguez & Smalley (1972) as Po. armatus . Pretzmann (1975) used these specimens to describe Potamocarcinus ( Po.) hartmanni Pretzmann, 1975 . The last species was later recorded from other localities in Tabasco ( Villalobos Hiriart & Álvarez 2008). Therefore, it seems reasonable to assume that Po. hartmanni has a northwestern distribution in rivers of the Gulf of Mexico drainage in the Mexican state of Tabasco, whereas Po. armatus is restricted more in the Southeast in rivers of both the Gulf of Mexico and Caribbean drainages in Guatemala and probable Belize as well.