taxonID	type	description	language	source
FEBCE5AD8B235E49A60056E5B8027C78.taxon	description	Figs 1, 2	en	Huang, Chao, Shih, Hsi-Te, Ahyong, Shane T. (2025): Four new freshwater crab species of the genus Megapleonum Huang, Shih & Ahyong, 2018 (Crustacea, Decapoda, Potamidae) from Guangdong, China. ZooKeys 1244: 1-27, DOI: 10.3897/zookeys.1244.148112
FEBCE5AD8B235E49A60056E5B8027C78.taxon	diagnosis	Diagnosis. Carapace broader than long, dorsal surface slightly convex, lateral margins covered in dense setae; postorbital, epigastric cristae confluent (Fig. 1 A). Maxilliped 3 sparsely covered in long setae; merus width ~ 1.4 × length; ischium width ~ 0.7 × length; exopod reaching beyond anterior edge of ischium, flagellum as long as merus width (Fig. 2 A). Ambulatory legs with dense setae; pereiopod 5 dactylus ~ as long as propodus (Fig. 1 A). Male anterior thoracic sternum very broad, width ~ 1.8 × length (Fig. 1 C). Male pleon large, broadly triangular, pleonite 6 width ~ 2.6 × length, telson width ~ 1.8 × length (Fig. 1 D). G 1 large, strongly sinuous, tip exceeding suture between thoracic sternites 4 / 5 in situ (Fig. 1 E); subterminal segment length ~ 3.2 × length of terminal segment (Fig. 2 C). Subterminal segment outer margin strongly concave; terminal segment strongly curved inwards, strongly tapering, sickle shaped, tip pointed downwards in dissected view (Fig. 2 C, F, G). G 2 subterminal segment tapering, bent outwards distally, flagelliform terminal segment ~ 1.8 × length of subterminal segment, apex blunt (Fig. 2 B).	en	Huang, Chao, Shih, Hsi-Te, Ahyong, Shane T. (2025): Four new freshwater crab species of the genus Megapleonum Huang, Shih & Ahyong, 2018 (Crustacea, Decapoda, Potamidae) from Guangdong, China. ZooKeys 1244: 1-27, DOI: 10.3897/zookeys.1244.148112
FEBCE5AD8B235E49A60056E5B8027C78.taxon	description	Description of male holotype. Carapace broader than long, ~ 1.2 × as wide as long; regions not pronounced, dorsal surface slightly convex, finely pitted; dense setae along lateral margins (Fig. 1 A). Frontal margin almost straight, deflexed (Fig. 1 A, B). Epigastric cristae and postorbital cristae relatively smooth, confluent; bifurcated groove between epigastric cristae (Figs 1 A, 2 A). Branchial regions not swollen (Fig. 1 A, B). Cervical groove shallow but visible (Fig. 1 A). Mesogastric region flat (Fig. 1 A). External orbital angle broadly triangular, outer margin slightly convex, confluent with anterolateral margin (Fig. 1 A, B). Epibranchial tooth granular, indistinct (Fig. 1 A, B). Anterolateral margin lined with indistinct single or partially fused granules; posterolateral margin posteriorly convergent (Fig. 1 A); posterolateral surface slightly rugose (Fig. 1 A). Orbits regular; supraorbital margins weakly cristate, infraorbital margins lined with fused granules (Fig. 1 B). Eyes normal (Fig. 1 A, B). Sub-orbital, pterygostomial and sub-hepatic regions generally smooth, pitted (Fig. 1 B). Antennules large, folded within broad fossae; antennae very short (Fig. 1 B). Median lobe of epistome buccal margin broadly triangular, lateral margins slightly sinuous (Fig. 1 B). Maxilliped 3 sparsely covered in long setae, merus subtrapezoidal, with slight median depression, width ~ 1.4 × length; ischium subtrapezoidal with shallow median sulcus, distomesial margin rounded, width ~ 0.7 × length. Exopod reaching proximal one-third of merus; flagellum as long as merus width (Fig. 2 A). Chelipeds (pereiopod 1) subequal (Fig. 2 D, E). Merus trigonal in cross-section, surfaces generally smooth; outer dorsal and ventral margins slightly crenulated, inner margin lined with large granules (Fig. 1 A, B). Carpus dorsal surface slightly rugose, with large spike at inner-distal angle, spinule at base (Fig. 1 A). Major cheliped palm length ~ 1.5 × height; dactylus 0.7 × palm length (Fig. 2 D, E). Palm surface pitted, occlusal margin of fingers with 7 – 9 irregular blunt teeth, with small gape when closed (Fig. 2 D, E). Ambulatory legs (pereiopods 2 – 5) slender, covered with setae (Fig. 1 A). Pereiopod 3 merus 0.6 × CL (Fig. 1 A). Pereiopod 5 propodus length 1.7 × height, approximately as long as dactylus (Fig. 1 A). Male thoracic sternum generally smooth, pitted, setae at margins and sparsely on sternites; sternites 1 – 4 width ~ 1.8 × length; sternites 1, 2 fused to form broad triangle; fused sternites 1, 2 demarcated from sternite 3 by sinuous transverse sulcus, sulcus lined with setae; sternites 3, 4 fused without obvious demarcation other than a line of setae (Fig. 1 C). Male sterno-pleonal cavity reaching anteriorly slightly beyond mid-length of cheliped coxa (Fig. 1 C). Male pleonal locking tubercle positioned at mid-length of sternite 5 (Fig. 1 E). Male pleon large, broadly triangular; somites 3 – 6 progressively narrower, not entirely confluent with each other; somite 6 width approximately 2.6 × length; telson width 1.8 × length; lateral margins almost straight, apex rounded (Fig. 1 D). G 1 large, strongly sinuous, tip exceeding suture between thoracic sternites 4 / 5 in situ (Fig. 1 E); subterminal segment length ~ 3.2 × length of terminal segment (Fig. 2 C). Subterminal segment outer margin strongly concave; terminal segment strongly curved inwards, strongly tapering, sickle shaped, tip pointed downwards in dissected view (Fig. 2 C, F, G). G 2 subterminal segment tapering, bent outwards distally, flagelliform terminal segment ~ 1.8 × length of subterminal segment, apex blunt (Fig. 2 B).	en	Huang, Chao, Shih, Hsi-Te, Ahyong, Shane T. (2025): Four new freshwater crab species of the genus Megapleonum Huang, Shih & Ahyong, 2018 (Crustacea, Decapoda, Potamidae) from Guangdong, China. ZooKeys 1244: 1-27, DOI: 10.3897/zookeys.1244.148112
FEBCE5AD8B235E49A60056E5B8027C78.taxon	distribution	Distribution. Baima Village, Huidong County, Huizhou City, Guangdong Province, China.	en	Huang, Chao, Shih, Hsi-Te, Ahyong, Shane T. (2025): Four new freshwater crab species of the genus Megapleonum Huang, Shih & Ahyong, 2018 (Crustacea, Decapoda, Potamidae) from Guangdong, China. ZooKeys 1244: 1-27, DOI: 10.3897/zookeys.1244.148112
FEBCE5AD8B235E49A60056E5B8027C78.taxon	etymology	Etymology. The species name is the Latin word falx which means sickle-shaped. It alludes to the sickle-shaped G 1 terminal segment of this species.	en	Huang, Chao, Shih, Hsi-Te, Ahyong, Shane T. (2025): Four new freshwater crab species of the genus Megapleonum Huang, Shih & Ahyong, 2018 (Crustacea, Decapoda, Potamidae) from Guangdong, China. ZooKeys 1244: 1-27, DOI: 10.3897/zookeys.1244.148112
7FB5A7F23BF559619415E29FCBFBB8C3.taxon	description	Figs 3, 4, 13 A	en	Huang, Chao, Shih, Hsi-Te, Ahyong, Shane T. (2025): Four new freshwater crab species of the genus Megapleonum Huang, Shih & Ahyong, 2018 (Crustacea, Decapoda, Potamidae) from Guangdong, China. ZooKeys 1244: 1-27, DOI: 10.3897/zookeys.1244.148112
7FB5A7F23BF559619415E29FCBFBB8C3.taxon	diagnosis	Diagnosis. Carapace broader than long, dorsal surface convex, lateral margins covered in dense setae; postorbital, epigastric cristae weak, almost confluent (Fig. 3 A). Maxilliped 3 merus width ~ 1.3 × length; ischium width ~ 0.7 × length; exopod reaching slightly beyond anterior edge of ischium, without flagellum (Fig. 4 A). Ambulatory legs densely setose; pereiopod dactylus shorter than propodus (Fig. 3 A). Male anterior thoracic sternum very broad, width ~ 1.9 × length (Fig. 3 C). Male pleon large, sublinguiform, pleonite 6 width ~ 2.5 × length; telson width ~ 1.7 × length (Fig. 3 D). G 1 large, slightly sinuous, tip exceeding suture between thoracic sternites 4 / 5 in situ (Fig. 3 E); subterminal segment length ~ 2.5 × length of terminal segment (Fig. 4 C). Subterminal segment outer margin slightly concave, outer distal margin bulging; terminal segment curved inwards, tip pointed upwards in dissected view, connected to a large mesoanterior-facing horseshoe shaped structure, large thick proximal pad on dorsal side (Fig. 4 C, F, G). G 2 subterminal segment tapering, slightly bent outwards distally, flagelliform terminal segment thick, ~ 1.6 × length of subterminal segment, apex blunt (Fig. 4 B).	en	Huang, Chao, Shih, Hsi-Te, Ahyong, Shane T. (2025): Four new freshwater crab species of the genus Megapleonum Huang, Shih & Ahyong, 2018 (Crustacea, Decapoda, Potamidae) from Guangdong, China. ZooKeys 1244: 1-27, DOI: 10.3897/zookeys.1244.148112
7FB5A7F23BF559619415E29FCBFBB8C3.taxon	description	Description of male holotype. Carapace broader than long, ~ 1.3 × as wide as long; regions not pronounced, dorsal surface convex; surface finely pitted, dense setae at lateral margins (Fig. 3 A). Frontal margin almost straight, deflexed (Fig. 3 A, B). Epigastric cristae and postorbital cristae rugose, low, almost confluent; bifurcated shallow groove between epigastric cristae (Fig. 3 A). Branchial regions not swollen (Fig. 3 A, B). Cervical groove shallow, barely visible (Fig. 3 A). Mesogastric region flat (Fig. 3 A). External orbital angle broadly triangular, outer margin slightly convex, confluent with anterolateral margin (Fig. 3 A, B). Epibranchial tooth granular, indistinct (Fig. 3 A, B). Anterolateral margin lined with indistinct single or partially fused granules; posterolateral margin posteriorly convergent (Fig. 3 A); posterolateral surface smooth (Fig. 3 A). Orbits regular; supraorbital margins weakly cristate, infraorbital margins lined with fused granules (Fig. 3 B). Eyes normal (Fig. 3 A, B). Sub-orbital, pterygostomial and sub-hepatic regions generally smooth, pitted (Fig. 1 B). Antennules large, folded within broad fossae; antennae very short (Fig. 3 B). Median lobe of epistome buccal margin broadly triangular, lateral margins straight (Fig. 3 B). Maxilliped 3 merus subtrapezoidal, with slight median depression, width ~ 1.4 × length; ischium subtrapezoidal with shallow median sulcus, distomesial margin rounded, width ~ 0.7 × length. Exopod reaching proximal one-third of merus; flagellum absent (Fig. 4 A). Chelipeds (pereiopod 1) subequal (Fig. 4 D, E). Merus trigonal in cross section, surfaces generally smooth, margins lined with long setae; outer dorsal margin slightly crenulated margins slightly crenulated, inner and ventral margin lined with large granules (Fig. 3 A, B). Carpus dorsal surface slightly rugose, with large spike at inner-distal angle, spinule at base (Fig. 3 A). Major cheliped palm length ~ 1.5 × height; dactylus 0.7 × palm length (Fig. 2 D, E). Palm surface pitted, occlusal margin of fingers with 7 – 9 irregular blunt teeth, with small gape when closed (Fig. 2 D, E). Ambulatory legs (pereiopods 2 – 5) covered with setae, especially dense on pereiopods 2 – 3 (Fig. 3 A). Pereiopod 3 merus 0.6 × CL (Fig. 3 A). Pereiopod 5 propodus length 1.7 × height, longer than dactylus (Fig. 3 A). Male thoracic sternum generally smooth, pitted, setae at margins and sparsely on sternites; sternites 1 – 4 width ~ 1.9 × length; sternites 1, 2 fused to form broad triangle; fused sternites 1, 2 demarcated from sternite 3 by sinuous transverse sulcus, sulcus lined with setae; sternites 3, 4 fused without obvious demarcation (Fig. 3 C). Male sterno-pleonal cavity reaching anteriorly slightly beyond mid-length of cheliped coxa (Fig. 3 C). Male pleonal locking tubercle positioned slightly posterior to mid-length of sternite 5 (Fig. 3 E). Male pleon large, sublinguiform; somites 3 – 6 progressively narrower; somite 6 width approximately 2.5 × length; telson width 1.7 × length; lateral margins almost straight, apex rounded (Fig. 3 D). G 1 large, slightly sinuous, tip exceeding suture between thoracic sternites 4 / 5 in situ (Fig. 3 E); subterminal segment length ~ 2.5 × length of terminal segment (Fig. 4 C). Subterminal segment outer margin slightly concave, outer distal margin bulging; terminal segment curved inwards, tip pointed upwards in dissected view, connected to a large meso-anterior-facing horseshoe shaped structure, large thick proximal pad on dorsal side (Fig. 4 C, F, G). G 2 subterminal segment tapering, slightly bent outwards distally, flagelliform terminal segment thick, ~ 1.6 × length of subterminal segment, apex blunt (Fig. 4 B).	en	Huang, Chao, Shih, Hsi-Te, Ahyong, Shane T. (2025): Four new freshwater crab species of the genus Megapleonum Huang, Shih & Ahyong, 2018 (Crustacea, Decapoda, Potamidae) from Guangdong, China. ZooKeys 1244: 1-27, DOI: 10.3897/zookeys.1244.148112
7FB5A7F23BF559619415E29FCBFBB8C3.taxon	distribution	Distribution. Dawuling Nature Reserve, Maoming City, Guangdong Province, China.	en	Huang, Chao, Shih, Hsi-Te, Ahyong, Shane T. (2025): Four new freshwater crab species of the genus Megapleonum Huang, Shih & Ahyong, 2018 (Crustacea, Decapoda, Potamidae) from Guangdong, China. ZooKeys 1244: 1-27, DOI: 10.3897/zookeys.1244.148112
7FB5A7F23BF559619415E29FCBFBB8C3.taxon	etymology	Etymology. The species name is the Latin word ferrumequinum, meaning horseshoe. It alludes to the horseshoe-shaped structure on the G 1 terminal segment of this species. Used as a noun in apposition.	en	Huang, Chao, Shih, Hsi-Te, Ahyong, Shane T. (2025): Four new freshwater crab species of the genus Megapleonum Huang, Shih & Ahyong, 2018 (Crustacea, Decapoda, Potamidae) from Guangdong, China. ZooKeys 1244: 1-27, DOI: 10.3897/zookeys.1244.148112
5B3B1E37FE7C52C9956DD1C067AFCC3A.taxon	diagnosis	Diagnosis. Carapace broader than long, dorsal surface slightly convex; postorbital, epigastric cristae confluent or almost confluent; external orbital angle bluntly triangular, confluent or almost confluent with anterolateral margin. Epistome buccal margin with triangular median lobe. Maxilliped 3 ischium longitudinally subquadrate, length ~ 0.7 × width; exopod reaching slightly beyond distal edge of ischium, flagellum absent to well-developed. Male anterior thoracic sternum very broad, width 1.8 – 2.0 × length. Male pleon large, broadly triangular to sublinguiform, tip of telson rounded. Female pleon linguiform to subovate. G 1 large, sinuous, reaching beyond male pleonal locking tubercle, subterminal segment outer margin slightly to strongly concave, terminal segment highly variable. G 2 subterminal segment tapering, bent to slightly bent outwards distally, thin to thick flagelliform terminal segment. Vulvae ovate, large, reaching suture of sternites 5 / 6, relatively widely separated.	en	Huang, Chao, Shih, Hsi-Te, Ahyong, Shane T. (2025): Four new freshwater crab species of the genus Megapleonum Huang, Shih & Ahyong, 2018 (Crustacea, Decapoda, Potamidae) from Guangdong, China. ZooKeys 1244: 1-27, DOI: 10.3897/zookeys.1244.148112
C80D0340D9645FCD8913422A01FB4647.taxon	description	Figs 5, 6, 7, 11 A, B, 13 B, C	en	Huang, Chao, Shih, Hsi-Te, Ahyong, Shane T. (2025): Four new freshwater crab species of the genus Megapleonum Huang, Shih & Ahyong, 2018 (Crustacea, Decapoda, Potamidae) from Guangdong, China. ZooKeys 1244: 1-27, DOI: 10.3897/zookeys.1244.148112
C80D0340D9645FCD8913422A01FB4647.taxon	diagnosis	Diagnosis. Carapace broader than long; dorsal surface slightly convex, postorbital, epigastric cristae weak, rugose, almost confluent (Fig. 5). Maxilliped 3 merus width ~ 1.2 × length; ischium width ~ 0.7 × length; exopod reaching slightly beyond anterior edge of ischium, without flagellum (Fig. 7 A). Ambulatory legs with dense setae; pereiopod dactylus shorter than propodus (Fig. 7). Male anterior thoracic sternum very broad, width ~ 2.0 × length (Fig. 6 B). Male pleon large, broadly triangular, pleonite 6 width ~ 2.6 × length; telson width ~ 1.8 × length (Fig. 6 C). Female pleon subovate (Fig. 6 E). G 1 large, strongly sinuous, tip exceeding suture between thoracic sternites 4 / 5 in situ (Fig. 6 D); subterminal segment length ~ 2.3 × length of terminal segment (Fig. 7 C – E). Subterminal segment outer margin strongly concave; terminal segment short, rounded, distoventrally with long setae, directed inwards, inner-proximal margin concave; tip presenting as protrusion on higher two-thirds of outer margin (Figs 7 C – E, 11 A, B). G 2 subterminal segment slightly bent outwards distally, flagelliform terminal segment thick, ~ 1.7 × length of subterminal segment, apex blunt, slightly swollen (Fig. 7 B).	en	Huang, Chao, Shih, Hsi-Te, Ahyong, Shane T. (2025): Four new freshwater crab species of the genus Megapleonum Huang, Shih & Ahyong, 2018 (Crustacea, Decapoda, Potamidae) from Guangdong, China. ZooKeys 1244: 1-27, DOI: 10.3897/zookeys.1244.148112
C80D0340D9645FCD8913422A01FB4647.taxon	description	Description. Carapace broader than long, ~ 1.2 × as wide as long in males (n = 4), ~ 1.3 × as wide in mature females (n = 4); regions not pronounced, dorsal surface convex; surface finely pitted, anterolateral regions slightly rugose (Fig. 5). Frontal margin slightly sinuous, deflexed (Fig. 5). Epigastric cristae and postorbital cristae rugose, low, almost confluent; bifurcated shallow groove between epigastric cristae (Fig. 5). Branchial regions not swollen (Fig. 5). Cervical groove shallow (Fig. 5). Mesogastric region flat (Fig. 5). External orbital angle broadly triangular, outer margin slightly convex, confluent with anterolateral margin (Figs 5, 6 A). Epibranchial tooth granular, indistinct (Figs 5, 6 A). Anterolateral margin lined with 10 – 14 granules; posterolateral margin posteriorly convergent (Fig. 5); posterolateral surface smooth (Fig. 5). Orbits regular; supraorbital margins weakly cristate, infraorbital margins lined with fused granules (Fig. 6 A). Eyes normal (Figs 5, 6 A). Sub-orbital, pterygostomial and sub-hepatic regions generally smooth, pitted (Fig. 6 A). Antennules large, folded within broad fossae; antennae very short (Fig. 6 A). Median lobe of epistome buccal margin triangular, lateral margins straight (Fig. 6 A). Maxilliped 3 merus subtrapezoidal, with slight median depression, width ~ 1.2 × length; ischium subtrapezoidal with shallow median sulcus, distomesial margin rounded, width ~ 0.7 × length. Exopod reaching proximal one-third of merus; flagellum absent (Fig. 4 A). Chelipeds (pereiopod 1) subequal (Fig. 7 F – I). Merus trigonal in cross section, surfaces generally smooth; outer dorsal margin slightly crenulated, inner and ventral margin lined with large granules (Figs 5, 6 A). Carpus dorsal surface slightly rugose, with small blunt spine at inner-distal angle, spinule at base (Fig. 5). Major cheliped palm length ~ 1.3 – 1.4 × height in males (n = 2), 1.4 – 1.5 × height in females (n = 4); dactylus 0.9 × palm length in males (n = 2), 0.9 – 1.0 × palm length in females (n = 4) (Fig. 7 F – I). Palm surface pitted, occlusal margin of fingers with 8 – 11 irregular blunt teeth, with very small gape when closed (Fig. 7 F – I). Ambulatory legs slender (pereiopods 2 – 5) covered with setae, especially dense on pereiopods 2, 3 (Fig. 5). Pereiopod 3 merus 0.6 – 0.7 × CL in both sexes (n = 8, Fig. 5). Pereiopod 5 propodus length 1.9 – 2.2 × height in males (n = 4), 2.1 – 2.4 × height in females (n = 4), shorter than dactylus (Fig. 5). Male thoracic sternum generally smooth, sparsely pitted; sternites 1 – 4 width ~ 2.0 × length; sternites 1, 2 fused to form broad triangle; fused sternites 1, 2 demarcated from sternite 3 by almost straight transverse sulcus; sternites 3, 4 fused without obvious demarcation (Fig. 6 B). Male sterno-pleonal cavity reaching anteriorly slightly beyond mid-length of cheliped coxa (Fig. 6 B). Male pleonal locking tubercle positioned at mid-length of sternite 5 (Fig. 6 D). Female vulvae ovate, large, reaching suture of sternites 5 / 6, relatively widely separated (Fig. 6 F). Male pleon large, broadly triangular; somites 3 – 6 progressively narrower; somite 6 width ~ 2.6 × length; telson width 1.8 × length; lateral margins almost straight, apex rounded (Fig. 6 C). Female pleon sub-ovate (Fig. 6 E). G 1 large, strongly sinuous, tip exceeding suture between thoracic sternites 4 / 5 in situ (Fig. 6 D); subterminal segment length ~ 2.3 × length of terminal segment (Fig. 7 C – E). Subterminal segment outer margin strongly concave; terminal segment short, rounded, distoventral region with long setae, directed inwards, inner-proximal margin concave; tip presenting as protrusion on higher two-thirds of outer margin (Figs 7 C – E, 11 A, B). G 2 subterminal segment slightly bent outwards distally, flagelliform terminal segment thick, ~ 1.7 × length of subterminal segment, apex blunt, slightly swollen (Fig. 7 B).	en	Huang, Chao, Shih, Hsi-Te, Ahyong, Shane T. (2025): Four new freshwater crab species of the genus Megapleonum Huang, Shih & Ahyong, 2018 (Crustacea, Decapoda, Potamidae) from Guangdong, China. ZooKeys 1244: 1-27, DOI: 10.3897/zookeys.1244.148112
C80D0340D9645FCD8913422A01FB4647.taxon	distribution	Distribution. Dawuling Nature Reserve, Maoming City, Guangdong Province, China.	en	Huang, Chao, Shih, Hsi-Te, Ahyong, Shane T. (2025): Four new freshwater crab species of the genus Megapleonum Huang, Shih & Ahyong, 2018 (Crustacea, Decapoda, Potamidae) from Guangdong, China. ZooKeys 1244: 1-27, DOI: 10.3897/zookeys.1244.148112
C80D0340D9645FCD8913422A01FB4647.taxon	etymology	Etymology. This species is named in honour of its discoverer, Jian Wang, in recognition of his contribution to this study.	en	Huang, Chao, Shih, Hsi-Te, Ahyong, Shane T. (2025): Four new freshwater crab species of the genus Megapleonum Huang, Shih & Ahyong, 2018 (Crustacea, Decapoda, Potamidae) from Guangdong, China. ZooKeys 1244: 1-27, DOI: 10.3897/zookeys.1244.148112
9E1C850AB36F51BD922339DC594E89F8.taxon	description	Figs 8, 9, 10, 11 C, D, 13 D	en	Huang, Chao, Shih, Hsi-Te, Ahyong, Shane T. (2025): Four new freshwater crab species of the genus Megapleonum Huang, Shih & Ahyong, 2018 (Crustacea, Decapoda, Potamidae) from Guangdong, China. ZooKeys 1244: 1-27, DOI: 10.3897/zookeys.1244.148112
9E1C850AB36F51BD922339DC594E89F8.taxon	diagnosis	Diagnosis. Carapace broader than long, dorsal surface slightly convex, postorbital, epigastric cristae confluent, sharp (Fig. 8). Maxilliped 3 merus width ~ 1.3 × length; ischium width ~ 0.7 × length; exopod reaching slightly beyond anterior edge of ischium; flagellum short, as long as dactylus (Fig. 10 A). Ambulatory legs without long setae, pereiopod dactylus shorter than propodus (Fig. 8). Male anterior thoracic sternum very broad, width ~ 1.9 × length (Fig. 9 B). Male pleon large, broadly triangular, pleonite 6 width ~ 2.4 × length, telson width ~ 1.8 × length (Fig. 9 C). Female pleon subovate (Fig. 9 E). G 1 large, sinuous, tip exceeding suture between thoracic sternites 4 / 5 in situ (Fig. 9 D); subterminal segment length ~ 2.7 × length of terminal segment (Fig. 10 C – E); subterminal segment thick, outer margin strongly concave, distal end slanted with outer-distal section highest; terminal segment short, both lateral margins slightly convex, bifurcated with one point being opening tip and other a smaller projection on outer margin, both pointing upwards (Figs 10 C – E, 11 C, D). G 2 subterminal segment thick, slightly bent outwards distally, flagelliform terminal segment thin, ~ 2.3 × length of subterminal segment (Fig. 10 B).	en	Huang, Chao, Shih, Hsi-Te, Ahyong, Shane T. (2025): Four new freshwater crab species of the genus Megapleonum Huang, Shih & Ahyong, 2018 (Crustacea, Decapoda, Potamidae) from Guangdong, China. ZooKeys 1244: 1-27, DOI: 10.3897/zookeys.1244.148112
9E1C850AB36F51BD922339DC594E89F8.taxon	description	Description. Carapace broader than long, males ~ 1.2 – 1.3 × as wide as long (n = 6); regions not all visible, dorsal surface slightly convex; surface pitted, anterolateral regions slightly rugose (Fig. 8). Frontal margin sinuous, deflexed (Fig. 8). Epigastric cristae and postorbital cristae confluent, sharp; bifurcated shallow groove between epigastric cristae (Fig. 8). Branchial regions not swollen (Fig. 8). Cervical groove obvious (Fig. 8). Mesogastric region flat (Fig. 8). External orbital angle broadly triangular, outer margin slightly convex, almost confluent with anterolateral margin (Figs 8, 9 A). Epibranchial tooth granular, indistinct (Figs 8, 9 A). Anterolateral margin lined with 10 – 14 granules; posterolateral margin posteriorly convergent (Fig. 8); posterolateral with weak striae (Fig. 8). Orbits regular; supraorbital margins cristate, infraorbital margins lined with fused granules (Fig. 9 A). Eyes normal (Figs 8, 9 A). Sub-orbital, pterygostomial and sub-hepatic regions generally smooth, pitted (Fig. 9 A). Antennules large, folded within broad fossae; antennae very short (Fig. 9 A). Median lobe of epistome buccal margin broadly triangular, lateral margins straight (Fig. 9 A). Maxilliped 3 merus subtrapezoidal, with slight median depression, width ~ 1.3 × length; ischium subtrapezoidal with very shallow median sulcus, distomesial margin rounded, width ~ 0.7 × length. Exopod reaching proximal one-third of merus; flagellum short (Fig. 10 A). Chelipeds (pereiopod 1) subequal (Fig. 10 F – I). Merus trigonal in cross section, surfaces generally smooth; outer dorsal margin slightly crenulated, inner and ventral margin lined with large granules (Figs 8, 9 A). Carpus dorsal surface slightly rugose, with small blunt spine at inner-distal angle, spinule at base (Fig. 8). Major cheliped palm length ~ 1.4 – 1.5 × height in males (n = 3), 1.4 × height in females (n = 2); dactylus 0.9 × palm length in males (n = 3), 0.8 – 0.9 × palm length in females (n = 2) (Fig. 10 F – I). Palm surface pitted, occlusal margin of fingers with 9 – 13 irregular blunt teeth, with very small gape when closed (Fig. 10 F – I). Ambulatory legs slender (pereiopods 2 – 5), with only very short setae on margins (Fig. 8). Pereiopod 3 merus 0.7 × CL in both sexes (n = 5, Fig. 8). Pereiopod 5 propodus length 1.7 – 2.0 × height in males (n = 3), 1.8 – 1.9 × height in females (n = 2), longer than dactylus (Fig. 8). Male thoracic sternum generally smooth, sparsely pitted; sternites 1 – 4 width ~ 1.9 × length; sternites 1, 2 fused to form broad triangle; fused sternites 1, 2 demarcated from sternite 3 by slightly sinuous sulcus; sternites 3, 4 fused with distinct sulcus (Fig. 9 B). Male sterno-pleonal cavity reaching anteriorly slightly beyond mid-length of cheliped coxa (Fig. 9 B). Male pleonal locking tubercle positioned at mid-length of sternite 5 (Fig. 9 D). Female vulvae ovate, large, reaching suture of sternites 5 / 6, relatively widely separated (Fig. 9 F). Male pleon large, broadly triangular; somites 3 – 6 progressively narrower; somite 6 width approximately 2.4 × length; telson width 1.8 × length; lateral margins almost straight, apex rounded (Fig. 6 C). Female pleon sub-ovate (Fig. 9 E). G 1 large, sinuous, tip exceeding suture between thoracic sternites 4 / 5 in situ (Fig. 9 D); subterminal segment length ~ 2.7 × length of terminal segment (Fig. 10 C – E). Subterminal segment thick, outer margin strongly concave, distal end slanted with outer-distal section highest; terminal segment short, both lateral margins slightly convex, bifurcated with one point being opening tip and other being smaller projection on outer margin, both pointing upwards (Figs 10 C – E, 11 C, D). G 2 subterminal segment thick, slightly bent outwards distally, flagelliform terminal segment thin, ~ 2.3 × length of subterminal segment (Fig. 10 B).	en	Huang, Chao, Shih, Hsi-Te, Ahyong, Shane T. (2025): Four new freshwater crab species of the genus Megapleonum Huang, Shih & Ahyong, 2018 (Crustacea, Decapoda, Potamidae) from Guangdong, China. ZooKeys 1244: 1-27, DOI: 10.3897/zookeys.1244.148112
9E1C850AB36F51BD922339DC594E89F8.taxon	distribution	Distribution. Yangdong County, Yangjiang City, Guangdong Province, China.	en	Huang, Chao, Shih, Hsi-Te, Ahyong, Shane T. (2025): Four new freshwater crab species of the genus Megapleonum Huang, Shih & Ahyong, 2018 (Crustacea, Decapoda, Potamidae) from Guangdong, China. ZooKeys 1244: 1-27, DOI: 10.3897/zookeys.1244.148112
9E1C850AB36F51BD922339DC594E89F8.taxon	etymology	Etymology. This species is named after the type locality, Yangdong County.	en	Huang, Chao, Shih, Hsi-Te, Ahyong, Shane T. (2025): Four new freshwater crab species of the genus Megapleonum Huang, Shih & Ahyong, 2018 (Crustacea, Decapoda, Potamidae) from Guangdong, China. ZooKeys 1244: 1-27, DOI: 10.3897/zookeys.1244.148112
