(Figs 1–17)
Talamita [sic] sexdentata Rüppell, 1830: 4 (in part), pl. 1 fig. 1.
Goniosoma sexdentatum.— A. Milne-Edwards 1861: 372 (fide Leene 1938, who examined the material).
Goniosoma Hellerii A. Milne-Edwards, 1867: 282; 1873: 167; Henderson 1893: 375.
Goniosoma annulatum.— De Man 1883: 151 (fide Leene 1937).
Goniosoma spiniferum Miers, 1884: 233, pl. 23 fig. C.; De Man 1887: 85 (discussion).
Goniosoma merguiense De Man, 1887 [1887–1888 a]: 82, pl. 5 figs 3–4; 1888 [1887–1888 b]: 335 (discussion); 1895: 560; 1897: pl. 12 fig. 9; Lenz 1905: 360; 1910: 556; Klunzinger 1913: 367.
Charybdis (Goniosoma) merguiensis.— Alcock 1899: 49, 55; Nobili 1899: 254; 1903: 31; 1906: 194, 196; Monod 1930: 140, fig. 7; Chopra 1935: 484, fig. 8; Shen 1937: 116 (key), 121, fig. 12; Leene 1937: 165; Chopra & Das 1938: 394.
Charybdis spiniferus.— Grant & McCulloch 1906: 18 (new record).
Charybdis (Charybdis) hellerii.— Leene 1938: 44 –49, figs 15–17; 1940: 182 (examination of the holotype of Goniosoma spiniferum); Stephenson 1972b: 11 (key), 32; 1976: 14; Kathirvel & Gopalakrishnan 1974: 286; Dai & Yang 1991: 233 – 234, fig. 126 (1), pl. 28 (6); Wee & Ng 1995: 32 –34, fig. 14a–g; Apel & Spiridonov 1998: 194 –197 (synonymy), figs 13– 15, 17; Davie 2002: 473 (synonymy and list of types); Galil et al. 2002: 110, unnumbered photograph; Padate et al. 2006: 587 (key); Yokes & Galil 2006: 754, fig. 2F; Yokes et al. 2007: 165, fig. 2d; Ng et al. 2008: 153 (list); Van Chung 2012: 168 (key), 174, fig. 12; Naderloo 2017: 174, figs 20.3d, 20.5, 20.7; Trivedi et al. 2018: 64 (list of Indian references).
Charybdis merguiensis.— Bouvier 1940: 252, fig. 162; Ward 1941: 5; Barnard 1950: 168, figs 27d, 32b; Fourmanoir 1954: 8, fig. 8; Badhra 1995: 257 (key), 258; Bhadra 1999: 410 (key), 411.
Charybdis vannamei Ward, 1941: 4, figs 5, 6; Stephenson 1972b: 32 (discussion); Santhanam 2018: 160.
Charybdis spiniferum.— Ward 1941: 5; Ng et al. 2001: 20 (discussion).
Charybdis (Charybdis) helleri.— Buitendijk 1947: 281; Stephenson et al. 1957: 492 (key), 493 (key), 497–498, figs 1a, 2i, 3j, pl. 1, fig. 4, pls 4c, 5b; Crosnier 1962: 75 (key), 77–78, figs 133–135, pl. 5 fig. 1; Apel 2001: 70.
Charybdis hellerii.— Edmondson 1954: 247 –248, fig. 32a–f (Hawai'i); Campos & Türkay 1989: 119 (first published record in the Western Atlantic); Lemaitre 1995: 643 –647, fig. 2; Tirmizi & Kazmi 1996: 29 (key), 45–47 (possibly in part), pl. 1, fig. B, possibly not fig. 23a–i; Tavares & Braga de Mendonça 1996: 151, 154 (key); Fransen et al. 1997: 179 (original material of Talamita sexdentata Rüppell, 1830 listed); Vannini & Innocenti 2000: 269, figs 30, 35, 93; Dineen et al. 2001: 778, figs 3–24 (larval and juvenile stages); Tavares & Amouroux 2003: 625, fig. 1; Alves Coelho & do Carmo Ferrão Santos 2003: 167, fig. 1; 2004: 192, fig. 5; Braga et al. 2005: 30, fig. 30; Sampaio & Rosa 2005: 58, fig. 1 (predation by octopus); Morán & Atencio 2006: 205; Oliveira de Almeida et al. 2006: 13, fig. 8; Figueiredo Frigotto & Serafim-Junior 2007: 228, fig. 1; Brockerhoff & McLay 2008: 71 (extensive data compilation); McMillen-Jackson 2008: 889, fig. 2; Lima et al. 2008: 37, fig. 3; Felder et al. 2009: 183, fig. 1b; Mizzan & Vianello 2009: 29, fig. 6; Boos et al. 2010: 1, fig. 1; Loebmann et al. 2010: 918, fig. 5; Medellín et al. 2001: 73, unnumbered fig.; Tavares 2011: 255, fig. 1b; Khvorov 2012: 39, unnumbered photographs; Bentes et al. 2013: 181, fig. 1; Cruz da Rosa 2014: 445, figs 1g–h; Elumalai et al. 2014: 338, fig. 1 (right, third row, Sacculina infestation); Watanabe et al. 2015: 219, fig. 3; McLay 2015: 830, fig. 71b; Abbas et al. 2016: 321, fig. 3; Cuesta et al. 2016: 622, 624, fig. 2B (Spain); da Silva Reis et al. 2016: 1, figs 1–3; Negri Pereira 2016: 1, figs 1, 17, 18, 19, 20b; Ng et al. 2017: 72 (list of Taiwan records); Ferry et al. 2017: 240, fig. 1; Negri & Mantelatto 2017: 282, figs 2a, 3a; Questel 2017: 1, unnumbered photographs; Santhanam 2018: 136, unnumbered fig.; Negri et al. 2018: 1771, figs 4–5; Evans et al. 2018: 641, figs 1, 2A, 4, 5 (Hawai'i).
Charybdis helleri.— Riedl 1983: 501, pl. 501, unnumbered fig.; Holthuis 1987: 350, fig. 10; Gómez & Martínez-Iglesias 1990: 70, fig. 1; Fransen 2014b: 316, fig. 31 [Guinea].
Charybdis merguiense.— Deb 1998: 144 (key).
Charybdis (Charybdis) merguiensis.— Deb 1998: 145.
Charybdis (Charybdis) helleri.— Jeyabaskaran et al. 2000: 52, pl. 38A; Dev Roy & Das 2000: 36, pl. 2 fig. 1, pl. 9 figs 7–8; Dev Roy & Bhadra 2011: 150 (key), 151.
Charybdis (Charybdis) spinifera.— Ng et al. 2008: 153 (list).
Charybdis (Charybdis) vannamei.— Ng et al. 2008: 153 (list).
Charybdis variegata.—Sant'Anna et al. 2012a: 12, fig. 2
non Cancer sexdentatus Herbst, 1783: 153, pl. 7 fig. 52 [= Charybdis feriata (Linnaeus, 1758) by lectotype designation
(Holthuis 1962)].
non Portunus annulatus Fabricius, 1798: 364.
non Portunus variegatus Fabricius, 1798: 364.
non Charybdis (Goniosoma) Hellerii. — Nobili 1906: 194, 195 [= Charybdis orientalis Dana, 1852] (fide Leene 1938: 70).
non Goniosoma Hellerii.— Klunzinger 1913: 367 [= Charybdis orientalis Dana, 1852] (fide Leene 1938: 70).
Material examined (directly or after new photographs). Type material of Goniosoma hellerii A. Milne- Edwards, 1867. New Caledonia, no exact locality, in dry condition: lectotype male, 60.0 x 85.0 mm, New Caledonia, M. Aubry-Lecomte, MNHN-IU-2000-732 (= MNHN-B 732); paralectotype male 49.0 x 72.0 mm, New Caledonia, coll. M. Jouan, MNHN-IU-2000-761 (= MNHN-B 761) [photographs provided by Danièle Guinot; specimens not directly examined by the authors].
Type material of Goniosoma merguiense De Man, 1887. Republic of the Union of Myanmar, Mergui Archipelago, 1886: 2 male syntypes (25.0 x 40.0 mm and 21.0 x 32.0 mm), leg. J. Anderson, RMNH. CRUS.D.1310 [photographs communicated by Charles Fransen; specimens not directly examined by the authors].
Type material of Goniosoma spiniferum Miers, 1884. 1 male holotype, about 13 x 17 mm, Queensland, Port Molle, between tide marks, Natural History Museum, NNM 1881.31 [photographs taken by Harry Taylor, NHM photo Unit and communicated by Paul F. Clark; specimen not directly examined by the authors].
Other material. Benin, Channel of Cotonou (Ancien Pont), 4 m, cast net, 24.v.2017: 1 male (pubescent, front with teratological anomalies), 43.5 x 66.7 mm, coll. C. E. Dessouassi, RBINS, INV. 150109; Benin, Channel of Cotonou (Ancien Pont), 4 m, lift net, 24.v.2017: 2 males (not pubescent), 46.4 x 68.5 mm and 46.6 x 68.7 mm, coll. C. E. Dessouassi, RBINS, INV. 150110; Benin, Channel of Cotonou (Ancien Pont), 4 m, lift net, 19.vi.2017: 2 males (not pubescent), 49.2 x 76.0 mm and 37.0 x 56.0 mm, coll. C. E. Dessouassi, RBINS, INV. 150111; Benin, Channel of Cotonou (Ancien Pont), 4 m, lift net, 24.v.2017: 2 males (not pubescent), 38.0 x 58.0 mm and 34.5 x 52.4 mm, coll. C. E. Dessouassi, RBINS, INV. 150112; 1 ovigerous female (not pubescent), 31.3 x 48.0 mm, coll. C. E. Dessouassi, RBINS, INV. 150113; Benin, Nokoué Lake (Agbato), 5 m, lift net, 24.v.2017: 1 female (not pubescent), 34.2 x 53.0 mm, coll. C. E. Dessouassi, RBINS, INV. 150114; New Caledonia, Noumea aquarium, 20.v.1966: 1 male (not pubescent), 47.0 x 68.0 mm, leg. Fierlant, RBINS, INV. 129463; Australia, Queensland, Shoal Point, under stones, at low tide, 14.iv.1983: 3 males (two strongly pubescent; smallest one weakly pubescent) (largest 37.0 x 56.0 mm), leg. R. De Blauwe, RBINS, INV. 129466; Australia, Queensland, north of Mackay, Shoal Point, under stones, at low tide, 26.v.1983: 3 males (largest: 41.0 x 63.0 mm) and 1 immature female (30.0 x 47.0 mm) [all specimens strongly pubescent], leg. R. De Blauwe, RBINS, INV. 129467; Australia, Queensland, Brampton Island, mangrove shore, no date: 1 male (pubescent, 27.0 x 43.0 mm), leg. B. Kaspiew, 1953, RBINS, INV. 129465; Philippines, Manilla, Langsheen National Park, rocks at the coast, 4.iii.1976: 5 males (scarcely pubescent and not pubescent; largest 30.0 x 46.0 mm), leg. J. Van Goethem, RBINS, INV. 129464.
Description. Carapace strongly pubescent, sparsely pubescent or glabrous, with a pair of short frontal ridges (sometimes hard to see), with a pair of nearly straight anterior protogastric ridges, with a continuous nearly straight mesogastric ridge, with shorter straight metagastric ridge (continuous or with short median gap), laterally followed (after a gap) by pair of broadly curved epibranchial ridges; no ridges on posterior half of carapace. Frontal region with 8 well developed teeth separated by deep incisions (3 pairs of true frontal teeth + 1 pair of teeth forming the inner border of orbit), subequal in length (very blunt in small specimens, blunt or sharp in large specimens). Anterolateral margin with 6 sharp teeth (the 5 first ones are subequal, the sixth one is subequal to the others or a bit longer). Junction between posterior margin and posterolateral margins arched (not angular).
Basal antennal article with granular ridge.
Chelipeds: merus with 3 strong anterior spines, posterior border toothless; carpus with strong spine on distomedial corner (this spine is posteriorly followed by a ridge running all along the carpus), with 3 lateral spines, of which only the two uppermost are visible in dorsal view, and of which the uppermost and the lowermost are posteriorly followed by a long ridge; propodus with 5 spines on its upper half: one spine in proximolateral position, 2 spines on the middle of propodus (1 dorsolateral and 1 dorsomedial which is posteriorly followed by carina), 2 distal spines (1 dorsolateral that is sometimes reduced to an angular protrusion and 1 dorsomedial which is posteriorly followed by carina), with 3 lateral carinae, with 1 medial carina terminated by a granule; tip of the various cheliped spines brown (except sometimes dorsolateral distal spine of propodus, when it is obsolete).
Pereiopod 5: posterior border of merus with subdistal spine; posterior border of carpus with distal spine (better seen in ventral view) [this character is very unusual in the genus Charybdis]; posterior border of propodus with 5– 13 denticles (sometimes up to 18 according to Negri Pereira 2016).
Telson of mature males: segment 6 about as long as wide, with borders convex on their distal 0.2. Gonopods as illustrated.
Size. Up to 85 x 60 mm (A. Milne-Edwards, 1867). The lectotype of Charybdis hellerii is apparently the largest specimen of the species ever recorded.
Habitat and biology. Intertidal to 47 m, substrates rocky/cobble, sandy, muddy bottoms, mangroves and coral reefs (Stephenson et al. 1957; Crosnier 1962; Wee & Ng 1995; Apel & Spiridonov 1998; Özcan et al. 2010; Dineen et al. 2001; Naderloo 2017). Exceptionally found as deep as 86 m (Stephenson 1972a). Dineen et al. (2001) stated that Charybdis hellerii appeared to be closely associated with habitat structure of both hard substrates and some plant structures and presents a secretive and cryptic behaviour during daytime. The same authors reported that they collected it only at salinities> 28 ppt and Trento Occhi (2016) demonstrated that it cannot survive in low salinity brackish water, with 100% mortality after two days at 20 ppt. This crab reaches sexual maturity within about one year (Dineen et al. 2001). Its lifespan is estimated to 2–3 years and it reproduces continuously during the year (Bolaños et al. 2012), but ovigerous females are less abundant during the warmest months (Mantelatto & Garcia 2001). The smallest ovigerous female recorded was 34.6 mm carapace width (Mantelatto & Garcia 2001) and the largest still immature females recorded by Oshiro & da Conceição (2001) were about 45 mm cw. The diameter of the eggs ranges from 0.224 to 0.266 mm in Turkish populations (Özcan et al. 2010). Fecundity in C. hellerii is high and ranges from 22,550 eggs to 3,200,000 eggs per brood depending on size of the female (for review see Dineen et al. 2001). It can store sperm to produce multiple broods (up to 6 broods per year in captive condition) and its larval development (through 6 zoeas and one megalopa stages) requires about 44 days at 24°C and 32-ppt salinity (Dineen et al. 2001). C. hellerii is an opportunistic feeder. Excluding organic matter, the most abundant food items found in its stomach by Sant'Anna et al. (2015) were crustaceans (25%), molluscs (21%) and macrophytes (13%). It is documented that C. hellerii is itself consumed by octopuses (Sampaio & Rosa 2005). Parasitism by Sacculina has been reported in Australian populations [1.3% of infection] (Stephenson et al. 1957) and India (Elumalai et al. 2014) but not yet in invasive populations.
Distribution. Native: South Africa, East Africa, Madagascar, Red Sea, Gulf of Aden, Socotra, southern Oman, Persian Gulf, Gulf of Oman, Pakistan, India, Sri Lanka, Mergui-Archipelago, Andaman Sea, Thailand, Malaysia, Philippines, Indonesia, Singapore, Australia, New Caledonia (Naderloo 2017). Invasive: Mediterranean (Steinitz 1929; Monod 1930; Galil et al. 2002; Yokes & Galil 2006; Yokes et al. 2007); Hawai'i (Edmondson 1954: isolated record; Evans et al. 2018: population); south Pacific: sea-chest of a fishing vessel in New Zealand (Dodgshun & Coutts 2003); western Atlantic from the Atlantic coast of the USA to the south of Brazil (for review see Negri Pereira 2016; Negri et al. 2018); tropical eastern Atlantic: Guinea-Bissau [11.5342°N, 17.0770°W: (http:// www.discoverlife.org/mp/20l?id=GBIF773871744 accessed 28.iii.2018)] and Benin (present material). An accidental isolated record on the hull of a ship in northwest Spain has been reported by Cuesta et al. (2016). The Mediterranean populations arrived from the Red Sea via the Suez Canal (Galil et al. 2002; Negri et al. 2018). It seems that the sources of invasive Western Atlantic populations are manyfold, consisting both of specimens from the western Indian Ocean and Mediterranean Sea group (major source) and from the Eastern Indian + western Pacific group (minor source, southern Brazil only) (Negri Pereira 2016; Negri et al. 2018).