Zilchia coronata, 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 : 604-607

Zilchia coronata n. sp.

( Figs 11; 14)

urn:lsid:zoobank.org:act:

TYPE MATERIAL. — Holotype. Guatemala • ♂ (32.7:20.6), Zacapa, San Lorenzo, Sierra de Las Minas [ 15°08’09”N, 89°37’22”W], Cerro de Los Monos , 2200 m elev., date and leg. unknown. UVGCR 518 . Paratypes. Guatemala • 1♂ (28.4:17.7) 2♀ (23.7:15.6; 24.2:15.9); collecting data unknown; UVGCR 519 .

DIAGNOSIS. — G1 with mesial process strong subtriangular, large (approximately 1.1 wider than width of apex in mesocaudal view), obliquely pointing downwards, lower margin unarmed, upper margin irregularly serrate; cephalic process as conical spine approximately as large as mesial process; apex with asymmetric margins, mesocaudal margin higher than laterocephalic one, entirely bordered by row of teeth and not overhanging apical field of spines, laterocephalic margin unarmed.

ETYMOLOGY. — The specific epithet refers to the Latin word “ corona ” due to the crown-like appearance of the G1 apex in mesocaudal view.

DISTRIBUTION. — Guatemala ( Zacapa); only known from the type locality ( Fig. 14).

DESCRIPTION OF THE HOLOTYPE

Carapace ( Fig. 11A, B) outline ellipsoid, widest at the middle (cw/cl 1.64), dorsal surface smooth, moderately convex longitudially, nearly flat transversally, regions ill defined, epi- and mesobranchial regions slightly more elevated. Pair of distinct gastric pits close to each other, on metagastric region. Cervical grooves nearly straight, deeper proximally, shallower distally, distal end failing to reach anterolateral margin. Postfrontal lobules small, almost indistinct; median groove distinct, shallow. Surface of carapace between front and postfrontal lobules smooth, distinctly deflected anteroventrally. Upper border of front smooth, strongly angulate, nearly straight in dorsal and frontal views, median notch indistinct; lower border carinate, nearly straight in dorsal and frontal views, slightly more projected anteriorly than superior one. Upper orbital margin carinate, lined with faint papillae to external side, smooth towards internal side; 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. 11C, D) narrow longitudinally; epistomial tooth low, slightly deflected anteroventraly, with carinate, smooth borders. Suborbital and subhepatic regions of carapace sidewall smooth ( Fig. 11C, D); pterygostomial regions with narrow, mostly smooth, weakly pilose patches only along outer borders of bucal frame ( Fig. 11C, D).

Endopod of Mxp3 ( Fig. 11C) with outer margin of ischium slightly convex, inner margin straight; merus with outer margin broadly rounded, inner surface of palp bearing tuft of short setae; exopod of 3rd maxiliped long, narrow, 0.74 length of outer margin of ischium ( Fig. 11C). Aperture of efferent branchial channel wide, subretangular, upper margin smooth ( Fig. 11D).

Chelipeds ( Fig. 11A, B) strongly heterochelous, similarly armed, right P1 larger. Larger cheliped ( Fig. 11A, B, E) 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 rounded, marked by single row of faint tubercles; distal upper margin arched, smooth. Carpus with inner margin with four faint low tubercles, prominent median spine, and smooth distally; outer margin rounded, smooth. Palm ( Fig. 11E) swollen (length/breadth 1.43), lateral surface smooth, dorsal border and mesial surface with very faint scattered tubercles, ventral border with irregular row of faint tubercles. Fingers of larger chela ( Fig. 11E) moderately gaping, those of smaller chela slightly gaping, tips not crossing; pollex with three subtriangular large teeth interspaced with smaller ones. Dactylus distinctly arched, slightly longer than palm (dactylus/palm 1.14, measured dorsally), proximal half of dorsal surface of dactylus with longitudinal, irregular rows of faint tubercles; pollex with lower surface bearing row of very faint tubercles. Ambulatory legs mostly disarticulated or broken; P4 and P5 still attached to body; slender, ratios dactylus/propodus and dactylus/merus as follows: P4 (right) = 1.42 and 0.82; P5 (left) = 1.50 and 0.92, respectively. P4 and P5 with dactyli bearing five longitudinal rows of sharp, corneous spines, increasing in size distally.

Thoracic sternum approximately as long as broad ( Fig. 11B). Thoracic sternites of Mxp3 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 short, thick, hook-shaped, emerging from nearby coxo-sternal condyle articulation, located proximally on sternite 8.

All pleonal somites free ( Fig. 11B); lateral margins of somites fringed by line of short setae; male pleon with somite VI distinctly longer than preceding ones, slightly shorter than telson (ration telson/somite VI = 0.92), lateral margins slightly concave. Male telson ( Fig. 11B) subtriangular, as long as wide, lateral margins nearly straight, fringed by line of short seate, tip rounded.

G1 ( Fig. 11 F-I) somewhat compressed mesolaterally, distal portion moderately arched laterocephalically in mesocaudal view; cephalic margin convex, with irregular rows of minute setae longitudinally on proximal half in mesocaudal view; caudal margin concave in mesocaudal view. Marginal suture along mesial surface, gently curved caudally on distal end; row of long setae along proximal portion of marginal suture. Marginal process large, lamelliform in mesocaudal view, not overreaching mesocaudal margin of apex. Lateral suture incomplete, marked by sulcus along the first 4/5 of caudal surface, shallower distally. Mesial process strongly developed, subtriangular, large (approximately 1.1 wider than width of apex in mesocaudal view), obliquely pointing downwards, lower margin unarmed, upper margin irregularly serrate. Cephalic surface slightly concave distally, with strong cephalic process as conical spine approximately as large as mesial process, situated transversally and contiguously to mesial process, obliquely pointing downwards. Apex oblong, elongated caudocephalically; its margins asymmetric, with mesocaudal margin higher than latercephalic one, entirely bordered by row of rounded teeth directed cephalad, not overhanging apical field of spines; lateroapical margin unarmed. Field of apical spines well developed, distally open (not concealed by apical margins), obliquely directed towards cephalic side, narrow, with short spines distributed along caudocephalic length.

G2 approximately as long as G1, flagellum very slender, regularly tapering.

REMARKS

The new species exhibits a quite peculiar G1, which appears to be similar to that of Z. falcata due to the strong, large mesial process. However, Z. coronata n. sp. can be easily distinguished from the other Guatemalan species of the genus by the following features of the G1: (1) upper margin of the mesial process serrate vs unarmed in Z. falcata ( Fig. 9C, D), Z. germani ( Fig. 10A, B), and Z. zilchi ( Fig. 10C, D); (2) cephalic process strong, long, and pointing in lateral direction vs reduced to a short spine pointing in mesial direction in Z. falcata ( Fig. 9D), Z. germani ( Fig. 10B), and Z. zilchi ( Fig. 10D); and (3) apex with mesocaudal margin entirely bordered by a row of teeth vs unarmed in Z. falcata ( Fig. 9C, D) and partially spined and strongly elevated in Z. germani ( Fig. 10B) or slightly elevated in Z. zilchi ( Fig. 10D).