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Ozius truncatus A. Milne-Edwards.
Ozius truncatus A. Milne-Edwards, Hist. Nat. Crust., vol. 1, p. 406, Pl. 16, Fig. 11. 1834.
Xantho deplanatus White, Juke's Voyage H.M.S. Fly, p. 337. 1847.
Ozius lobatus Heller, Reise der Novara, Zool. Bd. 2, abt. 3, p. 21, Pl. 2, Fig. 4. 1868.
Ozius truncatus Dana, U.S. Expl. Exped., vol. 13, Crust., pt. 1, p. 230, Pl. 13, Fig. 4. 1852.
— Miers, Cat. Crust. N.Z., p. 21. 1876.
— Haswell, Cat. Crust. Austr., p. 63. 1882.
— Filhol, Mission de l'Ile Campbell, p. 379. 1885.
— de Man, Abh. Senckenb. Natf. Ges., 25, p. 628, Pl. 21, Figs. 22, 23. 1902.
— Stimpson, Smithsonian Miscell. Coll., vol. 49, No. 1717, p. 60. 1907.
— Hale, Crust. S. Austr., p. 160. 1927.
— Lenz, Zool. Jahrb., Bd. 14, h. 5, p. 465. 1901.
(Not Xanthodius lobatus Milne-Edwards, 1880).
This species was originally recorded by Milne-Edwards from Australasia; Filhol, who had access to the same collections, states that Milne-Edwards' type specimen was from Australia, and we do not know whether there were more specimens from New Zealand; Filhol adds, however, that he himself had collected a specimen in New Zealand which was exactly the same. Dana has recorded the species from the Bay of Islands. According to Miers, specimens from both countries and from Lord Howe Island are in the British Museum, but again it is not clear whether true O. truncatus from New Zealand is included. Some and perhaps all of the specimens so named by Miers were those labelled O. deplanatus by White, these being included by Miers—with some doubt and certain qualifications of the description—in O. truncatus.
Now it is this amended description which most accurately applies to the specimens before us, viz., “the antero-lateral margins are granulous, the anterior tooth very broad and scarcely distinct; the second, obtuse; the third and fourth more acute, but still broad.” As this refers to White's specimens only, and the rest of O. truncatus as determined by Miers had the “latero-anterior margins short, and divided into four or five wide obtuse lobes,” and as our specimens have, for example, no sign of a fifth lobe, we conclude that the specimens before us are what White called O. deplanatus. And further, as the only clear statement of the record of O. truncatus in New Zealand, apart from O. deplanatus, depends on Dana's mention of
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the Bay of Islands, we conclud e that the commoner species in New Zealand, and possibly the only one, is what White called O. deplanatus.
The question therefore is whether O. deplanatus is a synonym of O. truncatus; and the question is further complicated by the fact that Heller has a species, O. lobatus, which appears to agree with the New Zealand specimens, though the localities mentioned by him for O. lobatus were Shanghai, Sydney, and Tahiti.
Specimens of the New Zealand species were sent in 1914 by the senior author to Dr. W. T. Caiman at the British Museum, who replied:—“The crab you send is undoubtedly the same species as the numerous specimens (including those from New Zealand) determined as O. truncatus in our collection. We have none determined as O. lobatus. De Man discusses the two species and figures the type-specimens of both in Abh. Senckenb. Natf. Ges., 25, p. 628, Pl. 21, Figs. 22-23, 1902. He thinks they are distinct species, but I should doubt it.” We have not seen the work referred to, and are unable at present to decide definitely upon the status of either White's O. deplanatus or Heller's O. lobatus. Lenz quotes with approval the opinion of Haswell that O. truncatus and O. lobatus are identical, and we can only repeat the caution (Chilton, Trans. N.Z. Inst., vol. 43, p. 556, 1911) that “a comparison of typical specimens is desirable before the two are combined.”
There is thus some doubt as to the correctness of the above synonymy, in which O. deplanatus and O. lobatus are reduced to synonyms of O. truncatus; but it does not seem to have been realised that if they are synonymous with one another but not with O. truncatus, the name deplanatus has priority over lobatus.
Locality.—N.Z. (White, Miers).
Bay of Islands (Dana).
Auckland (Hutton—specimens labelled O. truncatus are in the Canterbury Museum).
North part of the South Island (Filhol).
Cuvier Island (Grenfell and Barr).
Portland Island (C. Riesop).
Auckland, Tiri-tiri (O. lobatus) (Lenz).
Mokohinau (C. R. Gow).
“Common on the northern shores of New Zealand—from Portland Island northwards. During the ‘Hinemoa’ trip, 1914-1915, I got it at various places on the east and west coasts—Cuvier Island, Kaipara Harbour, etc.” (C.C., MS.).
This species scarcely extends to the South Island.
Distribution (O. lobatus).—Australia, Kermadecs.