Cancer raihoae Curtiss, 1938

Ng, Peter K. L., Eldredge, Lucius G. & Evenhuis, Neal L., 2011, The names of decapod and stomatopod Crustacea from Tahiti, French Polynesia, established by Anthony Curtiss in 1938 and 1944, Zootaxa 3099, pp. 43-56 : 48-49

Cancer raihoae Curtiss, 1938 [upai; papaá tara roa]

Cancer sanguinolentus Herbst, 1783: 161 .

Cancer raihoae Curtiss, 1938: 172 .

Curtiss (1938: 171–172) provided a long account of this edible species, which is clearly a species of Portunus (Portunidae) . Poupin (1996) commented that the record of “ Portunus pelagicus ( Linnaeus, 1758) ” from French Polynesia is dubious as he had not seen specimens, and Lai et al. (2010: 213), on examining a large series of specimens from many locations, concurred that the species is absent from there and that the large species present in French Polynesia is probably the same as the one in the Hawaiian Islands, P. sanguinolentus hawaiiensis . To ascertain the identity of Curtiss’s Cancer raihoae , it is useful to cite his account in full: “an edible crab, very good to eat; it is found along the sea-side and also goes up the sweet-water creeks to distances quite far inland. One specimen we measured was an inch and a half long, and two inches and a quarter wide, but I have seen many much larger than that. Its body is brown above with a dull blackish or purplish cast. Its under side is white. The spines along the sides of its shell have pale tips. Its front claws are brown above, whitish underneath, with the inner sides of the pincers reddish. It has five pairs of feet, and the two feet of the last pair are rounded and flattened at the end, like those of the edible blue crab in our country; these flattened feet serve it as paddles to swim with. On each side of the shell, towards the rear, a long spine sticks out, half an inch long in the specimens we mentioned above (and in possessing this spine on each side, the upai agrees again with our edible blue crab). Between the long spine and the eye on each side there are eight short spines along the edge of the shell, and then an indentation for the eye. Between the eyes, six teeth stick out of the edge of the shell, and there is a small spine beneath (by teeth I mean certain projections of the edge of the shell). The body is a little granulated on the upper side, but not very rough. The edges of the shell, of the tail, and of the legs as well, have some few tiny brown hairs. The legs are purplish and whitish. The upper shell is a little arched (convex, as they say) above. The female upai carries her spawn in the month of January. The mass of eggs is carried under the tail, which therefore sticks out a little to the rear; and the eggs reach forward from the rear as far as the third (from the front) pair of legs. Sometimes the load of eggs causes the tail to stand at right angles to the body. The female has her tail broad and brown; but the male, who keeps his tail clapped tight under the body, has it long and narrow, and its color, like the rest of the under side, is whitish. The male is also distinguished by his having a bright blue spot on the joint of each claw-leg next to the body, and another smaller one on the pincer-joint, but not on the fingers of the pincers. Both sexes have three dark, dull reddish eye-like spots, with whitish borders on the upper shell, towards the rear.”

The identities of the two subspecies of Portunus (Portunus) sanguinolentus (Herbst, 1783) are problematic. Stephenson (1968) described a new subspecies from Hawai’i and Fiji, Portunus (Portunus) sanguinolentus hawaiiensis , noting that it differed from P. sanguinolentus sanguinolentus by the dorsal surface of the carapace possessing a meshwork pattern. Although both species have the diagnostic three dark red to maroon spots on the posterior half of the carapace, the background colour is a uniform green to olive-brown in P. sanguinolentus sanguinolentus (see also Stephenson 1972). Ng et al. (2008) recognised both subspecies but in their revision of the allied Portunus (Portunus) pelagicus ( Linnaeus, 1758) species group, Lai et al. (2010: 226) briefly commented that Portunus sanguinolentus hawaiiensis is a good species, differing from P. pelagicus and P. sanguinolentus morphologically and genetically. Lai et al. (2010: 213, 214) also noted that Portunus sanguinolentus hawaiiensis was present in the Central Pacific and French Polynesia. Castro (2011: 70) recognised the Hawaiian taxon as a full species, commenting that “The Hawaiian subspecies represents a species different from Portunus sanguinolentus (Herbst, 1783) (P.K.L. Ng and J. Lai, personal communication)”. The recognition of Stephenson’s (1968) subspecies as a full species is followed here. While there is no doubt that the Hawaiian material belongs to a distinct species (Joelle Lai et al., unpublished data), differing markedly from P. sanguinolentus s. str. (and P. p e l a g i c u s) in the colour, form of the male first gonopod, and genetics, the status of the French Polynesian (and Tahitian) material is less certain. The material currently with J. Lai from Tahiti is close to P. hawaiiensis but no genetic data is available. However, Joseph Poupin (personal communication) has shown the authors photographs of fresh specimens from French Polynesia which suggests that both P. sanguinolentus and P. h a w a i i e n s i s may be present there.

Significantly, Curtiss apparently does not mention any meshwork pattern on the carapace, merely stating that “Its body is brown above with a dull blackish or purplish cast” ( Curtiss 1938: 171). This seems to agree better with Portunus sanguinolentus s. str. Joseph Poupin commented (personal communication) that “The place where Curtiss was living was Tautira where the lagoon has some resemblance with that of Opunohu Bay in Moorea where the specimen of P. sanguinolentus sanguinolentus was photographed. Tautira lagoon is protected by a barrier reef and it has river mouths. This is probably favourable to establishment of sand-muddy grounds with seagrass beds, as in Opunohu. Portunus sanguinolentus sanguinolentus seems to be located in sandy-muddy lagoons, with seagrass beds. Portunus sanguinolentus ? hawaiiensis seems to be located on coral grounds of the outer reef.” As indicated by Poupin’s comment, it is possible that the population from French Polynesia may in fact be a separate species (or subspecies) from P. sanguinolentus s. str. and P. h a w a i i e n s i s. As such, until all the Pacific material can be re-examined and the study by Lai et al. completed, it may be better to identify Cancer raihoae with Portunus sanguinolentus s. str. for the time being, especially in view of Curtiss’s colour notes. However, if later studies show that Cancer raihoae is actually P. hawaiiensis , then the former name has priority.