Planes major ( MacLeay, 1838 )

Wicksten, Mary K., 2012, Decapod Crustacea of the Californian and Oregonian Zoogeographic Provinces 3371, Zootaxa 3371, pp. 1-307 : 263-264

Planes major ( MacLeay, 1838)

( Fig. 60F)

Nautilograpsus major MacLeay, 1838: 66 .

Planes cyaneus Dana, 1851: 250 . — Chace 1951: 65; 1966: 646. — Hart 1963: 127; 1982: 216, fig. 89. — Manning & Holthuis 1981: 235.

Planes minutus: Rathbun 1904: 189 ; 1917: 253, pl. 63 (part). — Weymouth 1910: 63. Pl. 14. — Schmitt 1921: 272, pl. 46. — Johnson & Snook 1927: 397, fig. 353. — Garth 1946: 510.

Not Planes minutus ( Linnaeus, 1758) .

Planes major . — Ng & Ahyong 2001: 97, figs. 6 A, B (extensive synonymy).

Diagnosis. Carapace as long as broad, subcircular, almost smooth but for few faint lines on anterior, lateral regions, single blunt tooth behind postorbital angle, front sinuous. Chela broad, fingers somewhat deflexed, with several oblique lines on dorsal, ventral surfaces; somewhat obscure longitudinal line on lower portion of propodus; one tooth on inner margin of lower finger, 2–3 on dactyl. Pereopods 2–5 broad, somewhat flat, especially propodus, dactyl; anterior margins with dense fringe of setae, 1–3 spinules on lower distal margin of merus. Carapace length 15 mm.

Color in life. Very variable, mottled with yellowish brown or dark brown, white; or blue ( Schmitt 1921).

Habitat and depth. Pelagic among floating debris and barnacles ( Lepas spp. ) or on sea turtles, often near tail of sea turtle.

Range. Widespread between 41 o N and 35 o S in Pacific ; eastern Pacific from off British Columbia to Peru; Indian Ocean , South Atlantic Ocean ; rare in North Atlantic and Gulf of Mexico. Type locality Pacific Ocean at 28 o N, 174 o E (west of Midway I.) .

Remarks. Specimens of P. major from off the Pacific coast of Panama were encrusted by the naked barnacle Conchoderma virgatum (Spengler, 1790) . Johnson & Snook (1927, as P. minutus ) reported that these crabs can swim by sweeping pereopods 2–5 like oars, backward and forward in unison.

Ng & Ahyong (2001) re-examined of the type material of Nautilograpsus major and found that its generic designation is a junior synonym of Planes , but the species name takes precedence over P. cyaneus . See this paper for further discussion of the confused nomenclature of this crab.