Phrygiopilus senticosus, Ingo & Wehrtmann, 2025

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 : 593-595

Phrygiopilus senticosus n. sp.

( Figs 5; 15)

urn:lsid:zoobank.org:act:

TYPE MATERIAL. — Holotype. Guatemala • ♂ (27.0:15.8), Escuintla, specific locality unknown; 3.XI.2000; R. Hernández leg.; UVGCR 31 .

DIAGNOSIS. — G1 markedly sinuous, distal portion strongly curved in laterocephalic direction; caudal margin, in mesocaudal view, with clear median discontinuity due to distinct angled lateral lobe bearing minute setae. Mesial process as subtriangular conical spine at base of supra-apical process, directed cephalically. Supra-apical process with its margins and all over laterocephalic surface regularly and densely covered with spines (smaller proximally); mesial surface smooth, somewhat concave; supra-apical process slightly wider than long (ratio width/length roughly 1.2), approximately 0.2 times length of entire stem in mesocaudal view.

ETYMOLOGY. — The specific epithet “ senticosus ”, from Latin, means thorny, an adjective that refers to the densely spined supra-apical process of the male first gonopod.

DISTRIBUTION. — Guatemala ( Escuintla - the distribution record in the Fig. 15 is arbitrarily represented in the center of the department: approximately 14°10’N, 91°00’W).

DESCRIPTION OF THE HOLOTYPE

Carapace ( Fig. 5A) outline ellipsoid, widest at the middle (cw/ cl 1.70), dorsal surface smooth, nearly flat, regions ill-defined. Two distinct gastric pits, close to each other, on metagastric region. Cervical grooves somewhat deep, wide, slightly arched, distal end failing to reach anterolateral margin. Postfrontal lobules small, almost indistinct; median groove shallow. Surface of carapace between front and postfrontal lobules smooth, distinctly deflected anteroventrally. Front ( Fig. 5C, D) with upper border smooth, rounded, median notch absent; lower border carinate, slightly sinuous in dorsal and frontal views, slightly more projected anteriorly than upper one. Upper orbital margin ( Fig. 5D) lined with faint papillae; lower orbital margin crenulate, lined with faint papillae; exorbital angle very low, obtuse. Anterolateral margin of carapace with set of faint, minute, rounded teeth increasing in size from anterior to posterior portion; posterolateral margin smooth, marked by faint suture. Epistome ( Fig. 5C, D) narrow longitudinally; epistomial tooth low, slightly deflected anteroventraly, with carinate, smooth borders. Suborbital and subhepatic regions of carapace sidewall ( Fig. 5C, D) smooth; pterygostomial regions ( Fig. 5C) weakly pilose.

Endopod of Mxp3 ( Fig. 5C) with ischium subquadrate, its outer and inner margins nearly straight; merus with outer margin broadly rounded, inner surface of palp bearing short and long setae; exopod of third maxiliped long, narrow, 0.73 times length of outer margin of ischium. Aperture of efferent branchial channel ( Fig. 5D) wide, subretangular, upper margin slightly rounded, smooth.

Chelipeds ( Fig. 5A, B) strongly heterochelous, similarly armed, right P1 larger. Larger cheliped ( Fig. 5E) with merus subtriangular in cross section; dorsal margin rounded, with irregular row of low tubercles, fainter distally; ventromesial margin lined by longitudinal row of conical tubercles increasing in size distally; ventrolateral margin with single row of faint tubercles; distal upper margin arched, smooth; lower margin with subdistal row of faint tubercles. Carpus with inner margin bearing row of faint tubercles, a prominent median spine, and smooth distally; outer surface rounded, smooth. Palm ( Fig. 5E) swollen (length/width 1.78), smooth on both mesial and lateral surfaces, ventral margin with irregular row of very faint tubercles. Fingers of larger chela ( Fig. 5A, B, E) slightly gaping, those of smaller chela not gaping, tips not crossing; pollex with three subtriangular, large teeth interspaced with smaller ones. Dactylus of larger chela moderately arched, approximately as long as palm (dactylus/palm 1.054, measured dorsally); dorsal, mesial and lateral surfaces of dactylus and pollex with longitudinal rows of faint papillae. Ambulatory legs ( Fig. 5A, B) mostly disarticulated or broken; P5 still attached to body, slender, ratios dactylus/propodus and dactylus/merus 1.40 and 0.79, respectively; P5 with dactylus bearing five longitudinal rows of sharp, corneous spines, increasing in size distally.

Thoracic sternum approximately as longer as broad ( Fig. 5B). Thoracic sternites of 3rd maxillipeds and chelipeds completely fused, except for small notches at lateral edges of sternum. Male sternopleonal cavity densely pilose. Episternites 4-6 triangluar posteriorly, episternite 7 posteriorly truncate. Penis somewhat long and slender, hook-shaped, emerging from nearby coxo-sternal condyle articulation of P5 coxa, located proximally on sternite 8.

All pleonal somites free ( Fig. 5B); lateral margins of somites fringed by line of short setae; male pleon with somite VI trapezoidal, longest, slightly shorter than telson (ration length of telson/length somite VI = 0.92), lateral margins slightly concave. Male telson ( Fig. 5B) subtriangular, as long as wide, approximately as long as pleonal somite VI, lateral margins nearly straight, fringed by line of short seate, tip rounded.

G1 ( Fig. 5 F-H) markedly sinuous, distal portion noticeable curved in laterocephalic direction, compressed in caudocephalic direction, wider proximally in mesocaudal view; caudal margin, in mesocaudal view, with clear median discontinuity due to distinct angled lateral lobe bearing minute setae; cephalic margin broadly convex medianly in mesocaudal view; mesial surface with irregular row of short setae longitudinally along proximal half. 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 2/3 of caudal surface, shallower distally. Mesial process as subtriangular conical spine at base of supra-apical process, directed cephalad. Cephalic surface distally and subdistally crenulate, cephalic process absent; mesial surface produced into large, suboval supra-apical process. Supra-apical process with its margins, and all over laterocephalic surface, regularly and densely covered with spines (smaller proximally); cephalic surface distinctly folded proximally, slightly convex in caudocephalic direction medianly; mesocaudal surface smooth, distinctly concave. Supra-apical process slightly wider than long (ratio width/length roughly 1.2), approximately 0.2 length of entire stem in mesocaudal view; tip rounded. Apex narrow, slit-like, elongated mesolaterally, directed cephalad, upper and lower margins finely crenulated. Field of apical spines poorly developed, narrow, elongated mesolaterally, with minute spines nearly concealed by basal portion of supra-apical process and distal margin of cephalic surface of G1.

G2 slightly shorter than G1, flagellum very slender, regularly tapering, tip flattened.

REMARKS

In terms of the G1 morphology, Ph. senticosus n. sp. is most similar to Ph. strengerae , since their gonopods are strongly recurved cephalically and bear a strong median lobe due to a remarkable discontinuity on the median portion of the caudal margin (better seen in mesocaudal view). However, the following characters can readily distinguish both species: (a) the lateral lobe is less pronounced in Ph. senticosus n. sp., being shorter than the marginal process in mesocaudal view ( Fig. 5F), whereas this lobe is distinctly more pronounced in Ph. strengerae , being nearly as wide as the marginal process in mesocaudal view ( Fig. 4J); (b) the width of the stem median constriction is wider in Ph. senticosus n. sp. (ratio width at constriction/width at lateral lobe roughly 0.7 – measured in mesocaudal view) ( Fig. 5F) than in Ph.strengerae (ratio width at constriction /width at lateral lobe roughly 0.4 – measured in mesocaudal view) ( Fig. 4J); (c) the mesial process is present in Ph. senticosus n. sp. ( Fig. 5F) as a conical spine whereas it is absent in Ph. strengerae ( Fig. 4J); (d) the supra-apical process, particularly towards the mesocaudal surface, is more densely thorny in Ph. senticosus n. sp. ( Fig. 5 FH) than in Ph. strengerae ( Fig. 4J, K). Additionally, Ph. senticosus n. sp. is distributed in southern Guatemala (department of Escuintla), while Ph. strengerae occurs in the department of Alta Verapaz, in central-northern Guatemala.

The new species can be easily differentiated from the other Guatemalan species of Phrygiopilus by the strong lateral lobe and by the cephalic surface of the supra-apical process densely thorny.