Phrygiopilus acanthophallus Smalley, 1970

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 : 589-590

Phrygiopilus acanthophallus Smalley, 1970

( Figs 4 A-C; 15)

Phrygiopilus acanthophallus Smalley, 1970: 98 , figs 18, 19. — Rodríguez 1982: 88, figs 53, 54. — Villalobos F. 1982: 220 (in list). — Hobbs 1994: 101 (in list). — Guinot 1988: 14. — Rodríguez 2001: 440 (in key). — Villalobos Hiriart & Álvarez 2008: 297 (in list). — Ng et al. 2008: 176 (in list). — Cumberlidge et al. 2014: 144 and 147 (in table). — Wehrtmann et al. 2016: 779 (in list). — Acevedo-Alonso & Cumberlidge 2022: 581 (Appendix 2, in list).

Isabellagordonia ( Phrygiopilus) acanthophallus – Pretzmann 1971: 21 (in list); 1972: 93. — Hobbs et al. 1977: 149 (in list). — Reddell 1981: 111, fig. 16 (in map), 113. — Holthuis 1986: 594 (in list).

Isabellagordonia acanthophallus – Guinot 1994: 172.

TYPE MATERIAL EXAMINED. — Holotype. Guatemala • 1 ♂ (21.4:12.3); USNM 126110 , Alta Verapaz, Seamay Cave [ 15°24’14”N, 89°48’27”W; 929 m elev.], 1 km S of Senahú, about 200 km NE of Guatemala City ; 10.II.1968; G. Nicholas leg.

OTHER MATERIAL EXAMINED. — Guatemala • 1 ♂ (25.6:15.5); Zacapa, Santa Clara [? Finca Santa Clara: 15°07’N, 89°49’W; 1346 m elev.]; 7.VIII.1948; R. D. Michell leg.; FMNH 12210 • 1♂; Alta Verapaz, Seamay Cave, near Senahú ; 3.I.1973; M. Frania leg.; USNM 189299 • 2 ♂, 2 ♀; Alta Verapaz, Senahú, Finca Seamay, Cueva Seamay [ 15°24’14”N, 89°48’27”W; 929 m elev.]; 24-26. VIII.1969; S. & J. Peck leg.; USNM 128408 • 1 ♂ (19.0:11.0), 1♀ (23.2:13.8); Alta Verapaz, Senahú, Finca Seamay, Cueva Seamay [ 15°24’14”N, 89°48’27”W; 929 m elev.]; 24-26.VIII.1969; S. & J. Peck leg.; INPA 2182 • 1♂ (21.8:13.1); Alta Verapaz, in the surroundings of San Juan Chamelco [ 15°26’09”N, 90°20’17”W; 1375 m elev.], Río Chilax ; 1975; Büttger leg.; SMF 8867 • 1 ♂ (22.9:13.4) 2 ♀ (23.7:13.8; 25.4:14.3); Baja Verapaz, ruta 5 (antigua carretera a Salamá), Río Quilila (tributary to Río Negro or Chixoy); 15°12’53”N, 90°17’39”W; 1305 m elev.; 21.I.2014; I. S. Wehrtmann, M. Orozco, C. Magalhães & M. W. Dix leg.; UCR-MZ 3766-01 • 1 ♂ (13.7:8.5) 1 ♀ (16.9:10.5); Baja Verapaz, ruta 5 (antigua carretera a Salamá), Río Quililá (tributary to Río Negro or Chixoy) ; 15°12’53”N, 90°17’39”W; 1305 m elev.; 20.VII.2014; I. S. Wehrtmann & M. Orozco leg.; INPA 2473 • 1 ♂ (28.8:16.5); Baja Verapaz, tributary of Río Negro, approximately 18 miles north of Salamá, on road to Cobán [ 15°11’24”N, 90°17’40”W, 1382 m elev.], 22.IV.1947, Miller & Holoway leg.; INPA 2181 • 2 ♂; Baja Verapaz, tributary of Río Negro, approximately 18 miles north of Salamá, on road to Cobán [ 15°11’24”N, 90°17’40”W, 1382 m elev.], 22.IV.1947, Miller & Holoway leg.; USNM uncat .

DISTRIBUTION. — Guatemala ( Alta Verapaz, Baja Verapaz, Zacapa) ( Smalley 1970; Rodríguez 1982; Wehrtmann et al. 2016; this study) ( Fig. 15) and Mexico ( Magalhães & Wehrtmann 2025).

DESCRIPTION OF G1 ( Fig. 4 A-C)

Stem moderately sinuous, distal portion slightly curved in laterocephalic direction, compressed in caudocephalic direction, approximately the same width along the entire stem in mesocaudal view; caudal margin, in mesocaudal view, concave, sometimes with slight median discontinuity due to barely noticiable angled or rounded smooth lateral lobe; cephalic margin regularly convex in mesocaudal view. Marginal suture on mesial surface gently following the curvature of the stem, distinctly curved towards lateral side distally in mesial view; row of long and short setae along proximal portion of marginal suture. Marginal process wide, broadly rounded in mesocaudal view, not overreaching mesocaudal margin of apex. Lateral suture incomplete, marked by sulcus along first 3/4 of caudal surface, shallower distally. Mesial process as subtriangular conical spine at base of supra-apical process, directed cephalad. Cephalic process absent. Mesial surface produced into variable-length, rounded supra-apical process densely covered with short spines along its regularly widened margins; patch of spines denser distally. Supra-apical process with cephalic surface distinctly folded proximally, concave medianly; mesocaudal surface smooth, slightly concave. Supra-apical process with variable length ranging approximately from 0.2 to 0.5 times G1’s length in mesocaudal view, also ranging from slightly wider than long (ratio width/length roughly 1.2) to longer than wide (ratio width/length roughly 0.6); tip rounded. Apex oblong, elongated mesolaterally, directed cephalad; lower margin smooth (finely crenulated in some paratypes), upper margin (basal portion of supra-apical process) smooth. Field of apical spines poorly developed, narrow, elongated mesolaterally, with minute spines.

REMARKS

The number of male specimens assigned to Ph. acanthophallus available in the collections revised by us is somewhat low (see above). Nevertheless, one can notice some degree of variability in their G1s, particularly in the size of the supra-apical process. This process can be relatively short (roughly 1/5 the G1’s length) and wider than long (ratio width/length roughly 1.2) as in the male INPA 2181 from Baja Verapaz, 18 miles north of Salamá ( Fig. 4B), moderately long (roughly 1/3 the G1’s length) and nearly as wide as long (ratio width/ length roughly 0.9) as in the male USNM 1180974 from Chiapas, Mexico (cw 24.3 mm; see fig. 1A in Magalhães & Wehrtmann 2025), or longer than wide (ratio width/length roughly 0.6) and quite long (nearly half of the G1’s length) as in male SMF 8867 ( Fig. 4A) from Alta Verapaz, río Chilax. In the holotype, the supra-apical process is slightly longer than wide (ratio width/length roughly 0.8) and about 1/3 the G1’s length (see Smalley, 1970: 100, fig. 18). Interestingly, the G1 with the shorter supra-apical process belongs to the largest specimen examined (cw 28.8: male, INPA 2181) whereas the G1 with the longest supra-apical process belongs to a smaller specimen (cw 21.8: male, SMF 8867); this latter specimen, however, is similar in size to the holotype (cw 21.4), which has a supra-apical process of intermediate size. It remains to be seen, pending the availability of a larger sample, whether this variability in terms of a negative allometry is related to age.

Despite the variability of the supra-apical process, the G1 of all specimens examined herein share a unilobed mesial process in the form of a distinctly conical and acute spine ( Fig. 4A, B) and were, therefore, considered to be co-specific. However, the observed variability of the G1 might be indicative of the existence of a species complex (see also Remarks for Pseudothelphusa proxima Rathbun, 1905 , below). A better understanding of this situation should wait until a more abundant series of specimens from the species’ distributional range becomes available.