Morphological and molecular evidence for Gothus teemo gen. et sp. nov., a new xanthid crab (Crustacea, Brachyura, Xanthoidea) from coral reefs in the South China Sea, with a review of the taxonomy of Actaeodes consobrinus (A. Milne-Edwards, 1867) Author Yuan, Zi-Ming https://orcid.org/0009-0008-0009-2693 Department of Marine Organism Taxonomy and Phylogeny, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China & Laoshan Laboratory, Qingdao 266237, China & Shandong Province Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China Author Jiang, Wei 0000-0003-4767-8196 Department of Marine Organism Taxonomy and Phylogeny, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China & Laoshan Laboratory, Qingdao 266237, China Author Sha, Zhong-Li 0000-0002-2192-3758 Department of Marine Organism Taxonomy and Phylogeny, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China & Laoshan Laboratory, Qingdao 266237, China text Zoosystematics and Evolution 2024 2024-07-09 100 3 965 987 journal article 299644 10.3897/zse.100.117859 f17d3dc6-151e-4b2c-bfe6-1e3978daa701 15CA9ED4-C24C-4AD7-81AC-F699FA953FE8 Gothus teemo sp. nov. Figs 1 , 2 , 3 , 4 , 5 Type material. Holotype . China • 1 male ; CW 3.7 mm , CL 2.6 mm ; Triton Island , Xisha Islands ; 15 ° 46 ' 52.61 " N , 111 ° 12 ' 28.62 " E ; 5 m ; 10 May. 2024 ; Ziming Yuan coll.; 2404189149; MBM 287027 . Paratypes . China • 1 female ; CW 3.2 mm , CL 2.2 mm ; Meiji Reef , Nansha Islands ; 9 ° 52 ' 57.47 " N , 115 ° 33 ' 48.59 " E ; 27 Apr. 2023 ; Aiyang Wang , Bingqin Liu coll.; 2304278379; MBM 287026 • 1 male (decalcified); CW 3.2 mm , CL 2.4 mm ; Meiji Reef , Nansha Islands ; 9 ° 53 ' 1.15 " N , 115 ° 33 ' 37.42 " E ; 27 Apr. 2023 ; Aiyang Wang , Bingqin Liu coll.; 2304278461; MBM 287024 • 1 male (partially crushed); CW 4 mm , CL 2.7 mm ; Meiji Reef , Nansha Islands ; 9 ° 53 ' 1.15 " N , 115 ° 33 ' 37.42 " E ; 27 Apr. 2023 ; Aiyang Wang , Bingqin Liu coll.; 2304278486; MBM 287025 • 2 juveniles ; CW 1.8–2.2 mm , CL 1.3–1.5 mm ; Meiji Reef , Nansha Islands ; 9 ° 54 ' 25.75 " N , 115 ° 29 ' 49.44 " E ; 3 m ; 6 May 2022 ; Ziming Yuan , Yuli Sun , Shaobo Ma coll.; NS-MJ- 2022-1287 ; MBM 287023 • 1 juvenile ; CW 2 mm , CL 1.3 mm ; Meiji Reef , Nansha Islands ; 9 ° 53 ' 30.84 " N , 115 ° 34 ' 22.05 " E ; 5 m ; 11 Apr. 2024 ; Ziming Yuan coll.; 2404188048; MBM 287022 . Description. Carapace (Figs 1 , 3 A ) broader than long, CW about 1.5 times the CL , dorsal surface bearing round granules, regions well defined, 1 M separated from 2 M by shallow transverse groove; 2 M indistinct divided, lateral lobe with elevated pointed tuberosity; 3 M distinct, undivided; 4 M indistinct; 1 L, 3 L, 4 L indistinct; 2 L, 5 l, 6 L distinct, with elevated sharp tuberosity each on 2 L, 5 L; 1 P distinct, 2 P indistinct, flat; 2 M, 5 L, and 6 L regions each with a tuft of setae; front wide, about 0.4 times CW , not protruding, divided into two slightly triangular lobes by a V-shaped notch, a small pore visible from front introduced from median notch (Fig. 1 B ), frontal lobes and dorsal inner orbital angle separated by shallow depression; eyestalks densely granulated; area behind outer orbital angle slightly concave, not forming a subhepatic cavity; anterolateral margin starting from subhepatic region; first tooth nearly completely reduced; subsequent three teeth developed; second and third teeth nearly equal; fourth tooth smaller; carapace widest at second tooth; posterolateral margin almost straight; subhepatic region densely granulated; posterior margin nearly straight. Epistome (Fig. 1 B, E ) central region with short median projection on posterior margin pronounced; lateral regions with undulating posterior margins; maxilliped 3 (Figs 1 B, E , 3 B ) granulated; ischium subrectangular; presenting submedian groove; merus subquadrate; anterior margin indented; external anteroexternal angle expanded. Antennule (Fig. 1 B, E ) folding transversely; basal segment of antenna subrectangular; contacting ventral external frontal margin and ventral internal orbital angle; antennal flagellum filling orbital hiatus. Chelipeds (Figs 2 A, B , 3 C ) symmetrical; meri short; carpi robust, with square-shaped outward expansion, surface granulated, aggregated into nodules; palms dorsally with three protuberances, outer and dorsal surfaces densely granulated; fingers elongated, with triangular teeth, tips sharp, crossing at extremities when closed; dorsal surface of movable finger with three granular ridges; outer surface of immovable finger with two granular ridges. Ambulatory legs (Figs 1 A, D , 3 D ) meri flattened, P 5 merus length about 3.6 times width of distal end, granulated dorsally and along anterior and posterior edges; carpi granulated dorsally and along anterior edge, dorsal surface with a grooved indentation near anterior edge; propodi granulated dorsally and along edges; dactyli elongated, margins armed with granules and setae, terminal end chitinous, sharp, slightly curved backward, dactylo-propodal lock very weak and inconspicuous. Male thoracic sternum (Fig. 2 C ) with sternites 1 and 2 completely fused, suture between sternites 2 and 3 straight, complete, sternites 3 and 4 mostly fused, suture between them visible only at margins, sternites 3 short, sternite 4 with central longitudinal groove, tubercle of sterno-pleonal lock (press-button mechanism) located on posterior of sternite 5. Male pleon (Figs 2 C, E , 3 F ) narrow; pleonites 3 to 5 completely fused, lateral margins of pleonite 6 slightly concave, telson long and broad, width slightly greater than length, truncated oval, basal margin wider than terminal margin of pleonite 6; paired tufts of setae present on margins of middle part and terminal margin of pleonites 3–5 and terminal margin of pleonite 6. Female pleon (Figs 2 D, F , 3 E ) oval-shaped, margins of pleonite 6 slightly concave; telson triangular; vulva longitudinally ovate, located at upper of sternite 6, occupying anteromedial half, near sternites 5 / 6 (Fig. 2 G ). G 1 (Fig. 3 G, H, I, J ) slender, distal lobe prominent but not excessively elongated, long setae on inner subdistal side, small spines on outer side. G 2 (Fig. 3 K, L ) short, distal lobe elongated, slightly curved upwards. Live coloration. Overall white to coral pink in coloration, carapace adorned with symmetrical black to brown stripes, ambulatory legs and chelipeds bearing stripes of similar coloration, anterior part of chelipeds carpus red (Figs 4 , 5 ). Fingers brownish-black, the coloration of immovable finger extending onto the palm along both the inner and outer surfaces in male (Fig. 2 A, B ). Etymology. The new species is named after Teemo, a character from the MOBA (Multiplayer Online Battle Arena) video game League of Legends. This character, modeled after a raccoon, has a fluffy, diminutive stature with a brown and white intermingled fur coat. This alludes to the new species’ small size, densely covered short setae, and brown-striped coloration. Distribution. Currently known from the type locality at Triton Island, Xisha Islands (Paracel Islands), and Meiji Reef (Mischief Reef), Nansha Islands ( Spratly Islands ), it inhabits crevices in shallow coral reefs. Remarks. Apart from the members of the subfamily Euxanthinae already compared in the remarks of Gothus gen. nov. , the species is most similar to Actaeodes consobrinus (A. Milne-Edwards, 1873 ) . They share similarities in the carapace outline, the shape of the male pleon, and even in the pattern of the live coloration. However, G. teemo sp. nov. can be differentiated from A. consobrinus by the following features: the first tooth on the anterolateral margin of the carapace is completely reduced, almost invisible (Figs 1 A, C , 3 A ) (vs. the first tooth low but still visible in A. consobrinus ; Figs 7 A, B , 8 A , 9 A, B ); carapace regions more pronounced, with tufts of setae (Figs 1 C , 3 A ) (vs. carapace regions flatter, without tufts of setae in A. consobrinus ; Figs 7 A, B , 8 A , 9 A, B ); cheliped carpus with square-shaped outward expansion (Fig. 1 A ) (vs. cheliped carpus nearly spherical in A. consobrinus ; Figs 7 A , 8 A, B ); male pleon relatively broader, telson width slightly greater than length (Figs 2 F , 3 F ) (vs. pleon very narrow, telson longer than wide in A. consobrinus ; Figs 7 D , 8 E ); G 1 distal lobe shorter (Fig. 3 G – J ) (vs. G 1 distal lobe significantly elongated in A. consobrinus ; Fig. 8 F – G ).