Revision of the spider crab genus Maja Lamarck, 1801 (Crustacea: Brachyura: Majoidea: Majidae), with descriptions of seven new genera and 17 new species from the Atlantic and Indo-West Pacific Author Ng, Peter K. L. Author Forges, Bertrand Richer De text Raffles Bulletin of Zoology 2015 2015-05-29 63 110 225 journal article 10.5281/zenodo.5384590 2345-7600 5384590 40BCDD62-D35E-46D1-95A3-2CC0DF219DEE Rathbunaja bisarmata ( Rathbun, 1916 ) ( Figs. 59A, B , 61A–D , 63A, B , 64A, B , 65A–D , 66A–G ) Maja bisarmata Rathbun, 1916: 553 . – Serène, 1968: 57 . – Griffin, 1976: 199 , Fig. 7b . – Griffin & Tranter, 1986: 211 (key). Material examined. Holotype : male (20.3 × 15.6 mm ) ( USNM 48220 ), station 5519, Point Tagolo Light , off northern Mindanao , 80°47’N 123°31.25’E , Philippines , coll. RV Albatross , 9 August 1909 . Others : Philippines – 1 male (37.1 × 29.6 mm ) ( ZRC 2013.1274 ), Balicasag Island , Panglao , Bohol , 200–300 m , coll. fishermen with tangle nets, 2 March 2004 . Diagnosis. Carapace relatively narrow ( Fig. 59A, B ). Pseudorostral spines long, diverging ( Fig. 59A, B ). Median row with 2 median gastric spines; 2 cardiac spines; 2 intestinal spines ( Fig. 59A, B ). Basal antennal article with 2 relatively short distal spines not strongly diverging ( Fig. 61A–D ). Ischium of third maxilliped proportionately shorter ( Fig. 63A, B ). Ambulatory merus relatively shorter, stouter ( Figs. 59A, B, 65B, D ). Male telson subtriangular ( Fig. 64A, B ). G1 gently curved, distal part relatively shorter ( Fig. 66A–G ). Remarks. This is a very poorly known species and although it has been treated as a valid Maja species by Griffin (1976) (who examined the type) and Griffin & Tranter (1986) , a re-examination of the holotype shows otherwise. Although Rathbun (1916) placed this species in Maja , its antennal flagellum is actually just outside the orbit. In fact, the species is very close to Leptomithrax kiiensis , described by T. Sakai (1969) on the basis of a large male 55.0 by 44.5 mm from Kii Minable in Japan . Tune Sakai (1969 , 1976 ) placed this species in Leptomithrax because its antennal flagellum is just outside the orbit, even if it is not to the same degree as other congeners. The holotype male of Maja bisarmata is relatively small ( Fig. 59A ) and although its G1 is not fully developed ( Fig. 61A–D ), it shows enough features. A recent larger specimen from the Philippines agrees well with the type male in its carapace form, antennal basal article, epistome, structure of the third maxilliped, relatively short ambulatory legs, thoracic sternum, male abdomen and structure of the G1, and we are confident they are conspecific. These features make it unlikely that Maja bisarmata is the juvenile form of the more common new species described here from the Philippines , Rathbunaja ursus . Fig. 63. Third maxillipeds, Rathbunaja species. A , R. bisarmata , holotype male (20.3 × 15.6 mm) (USNM 48220), Philippines; B, R. bisarmata , male (37.1 × 29.6 mm) (ZRC 2013.1274), Philippines; C, R. kiiensis , male (49.9 × 39.1 mm) (NSMT-Cr 5094), Japan; D, R. kiiensis , ovigerous female (43.8 × 37.3 mm) (NSMT-Cr 6419), Kyushu-Palau Ridge; E, R. ursus n. sp. , holotype male (50.1 × 41.5 mm) (NMCR, ex ZRC 2013.1275), Philippines; F, R. ursus n. sp. , paratype male (41.6 × 32.8 mm) (ZRC 2013.1276), Philippines; G, R. ursus n. sp. , paratype female (45.0 × 36.0 mm) (ZRC 2001.0594), Philippines; H, R. ursus n. sp. , paratype ovigerous female (46.8 × 36.6 mm) (ZRC 2001.0594), Philippines. Maja bisarmata Rathbun, 1916 , is very close to Leptomithrax kiiensis T. Sakai, 1969 . Comparisons of Rathbun’s species with material of L. kiiensis from Japan as well as the descriptions and figures of the species by T. Sakai (1969 , 1976 ), Miyake (1983) and Ikeda (1998) show minimal differences. The main difference appears to be the relative lengths of the merus of the ambulatory leg, which in R. kiiensis , is proportionately longer and more slender ( Figs. 59C, E , 65F ) than that of R. bisarmata ( Figs. 59A, B , 65B, D ). The distal part of the G1 of R. kiiensis is more curved and slightly longer than that of R. bisarmata ( Fig. 66H–M versus Fig. 66A–G ). As such, both species are recognised for the time being. As discussed under the genus, the distinctive features of these two species (as well as two other new ones here described) warrant the establishment of a new genus, Rathbunaja , for them.