TheThemalacological malacological society of Japan TAKI:Chiton Fauna of Japan (1) 341 Tesch, J.J. 1904. The Thecosomata and Gymnosomata of the Siboga Expedition. Siboga Monogr. 52, 92 pp., 6 pls. 1913. Das Tierreich. 36 Lief. Mollusca. Pteropoda. 16+154 pp. -- --- 1946. The thecosomatous Pteropoda, i, The Atlantic. Dana Rept. 28, 82 pp., 8 pls. - 1948. The thecosomatous Pteropoda, ii. The Indo-Pacific. Dana Rept. 30, 45 pp., 3 pls. in Tokioka, T. 1955. 0n some plankton animals collected by the Syunkotu-maru Pteropoda. Publ. Seto Mar. Biol. Lab. May-June 1954, iv. Thecosomatous 5 (1), pp.59-74, 7 pls. des Vayssiere, A. 1915. Mollusques Eupteropodes provenant des campagnes Alice. Res. Camp. Scient. Albert ler de yacht Hirondelie et Princesse Monaco, 47, 224 pp., 14,pls. -c -V' -:) Eil Xg iilill }: t7 ti" 1 3till re e'zz. vN <O ?i･ir-･ tsE ･t.-: "G 'L JI{ Jkij )k( e-IJ: lk 21 lfl} i }]i' l･g yt< rXr,,. FtF On the Chiton Fauna of Japan (1) The Status of Ischnochiton comPtus and L boninensis Iwao TAKI of and Animal Husbandry, Department of Fisheries, Faculty Fisheries Hiroshima University, Fukuyama, Japan (firX Text-figs. 1-6) Taki devoted himself to the Though my elder brother Isao (1898-1961) of Chitons and a number of papers study the fauna of Japanese published regret that work was inter- in this field<Iw. Taki, 1962), it is my deep his all the in identifying all species rupted by his death in 1961, planning animals was left unfinished. After and compiling a monograph of these as well as his death his specimens of Chitons and relevant literatures to succeed notes were handed over to me, andIhope that Imay be able the work hereafter. It is needless to say that I have great respect to my much effort in his researches on Chitons. Also brother who paid Japanese NII-Electronic LibraryMbrary Service The malacological society of Japan 342 VENUS:22 (4) 1964 ' I am very grateful to those who gentlemen have sent valuable Chiton specimens to my brother at various occasions from various localities. It is a that pity all his scientific property liteirantures (specimens, and notes) was practically lost by the War Il[ which has been col!ected and piled up for many years (during the war-tki'ie he has been resident in the Nanking Museum, China, whe:･e he w.:`s 2ppointed Chief Researcher in 1942, and after the war his property was taken over by the hostile government). Since he repatriated in Japan in 1946, he has been compelled to collect specimens ; nd literature newly, and though they wei'e fairl> :iL]unclantly collected they did not attuin the !'cz,rmer level, especially he ccuitd nott get rare speclmens agaln. ' In order to promote our knowledge of Japanese Po]yplacophox"a, I think it necessary to review the known species re$pectively. In this short note is dealt with a common spccies of Ischnochiton in Japan. The status of Ischnochiten coinPtzts and I. boftin･Efsssg's The specific identification of the most common species of ib('lt?torthiton in the rocky shore of Japan has been not quite easyv ; Isao li-nki (1924) showed it undeterminedin his firstpaper. But later he identii''/edit with L co7nPtzfis Gould, which was unfigured in Pilsbry's description in Manual of Conchology In 1933 (1892). Bergenhayn described L bofr･iitensi･; as a new species from Misaki, Kanagawa Prefecture, Shimonoseki and Chichi- jima in Bonin Islands, but did not compare with co7nPtifs, it t. apparently unaware of the of species. presence that In tlie same year I'$zo Taki annottnced and reviewed BergenhaynLs paper, saying that bonntefz,sis-- thaanit?#..,i '.conzPtzes. Dall, ]926, and iebrifzzts However, he later (1938, p. 3S9,/ discriminated two species [)s follows; e: upon examination of nurnerous specimens collected froin the t:Nrpe locali- ty and from other places of Japan, I can clear.ly distinguish two forms, one of which has smooth and the other distinctly striated scttles, both occurring almost always :tn the same habitat. I do not, therefore, hesitate to consider the specimens of smooth scales as L eomPtzfs and that of striated scaies as L boninensis of BergenhaynQ933)." ･ibid., Also he p. 370) -- treated thaanztmi comPtzvs. His view was clearly m.etnir'ested in his NII-Electronic Library Service The malacologicalsocietymalacological society ofJapanof Japan '' TAki:Chiton Fauna of Japan (1) 343 f "D6butsu-Zukan" figures and descriptions in (Encyc]. Fauna Jap, an) (1947) in which he discrirninated these two .species as distinct, with the follow- ing characters: L comPtzts (Gould) (Usu-hizara-gai). ... Girdle scale larger and less in number, its surface smooth; outline of animal short and wide; posterior area of tail valve narrower; distribution-from Honsha . to Philippines and Outer South Sea Islands. f. bofzinensis Bergenhayn (Hoso-usu-hizara-gai). Girdle scale smaller and provided with 12-15 shallow grooves; di$tribution-･from HonshU to South China. In so far as the surface sculpture of girdle scales is conce'rned, his treatment is inappropriate, because though he says that in comPtzas the scales are smooth, they are grooved in the original description. namely: ``Girdle rLPilsbfy, narrow, imbricated vvith small elongated grooved scales''; "....sca]es, 1892, p.117). Also Carpenter"s description (ibid.) runs some- times very slightly striated..... the striulation of the scales can seldom " be seen. ... Nierstrasz (1905) figured and described I. comPtus (p. 24, pl. 1, fig. 10) but the outline of the animal js considerably oval, which is narrow ante- riorly arid very wide posteriorly. Though the out!ine of the animal is subjected to a wide range of variation I have never met with such a wide specirnen, at least frem Japanese localities. He does not explain the surface of the girdle scale, but it seems to be smooth judging from his figure (pl. 3, fig. 84). The identification of this species seems to need further examination. as a new species, When Bergenhayn i (1933)described bonineitsis he compared it with longiaymba, which occurs in New Zealand, so that his comparison is out of the focus from the view-point of locality. Moreover the name longiaymba Quoy & Gaimard is preoccupied and should be called maorinus Iredale,1914. IIis description of beninensis in the outline of the animal, dimension, sculpture of shell-plates, their interior, gjrdle-scale etc. well agrees with the characters ef comPtus. He says<p. 11) that "Dorsalschuppen ....haben eine glatte oder auch schwach gefurchte Dor- NII-Electronic Library Service TheThemalacological malacological society of Japan 344 VENU.S..: 22 (4) 1964 salseite,:' but the scale shown on his Text-fig. 3a is smooth; also he did not describe the number of shallow grooves. In the figure of the radula (Text-fig. 3e) he failed to show the basal part of the first lateral tooth (cf. Is. Taki, 1938, pl.27, fig. 6) and the･ stem of the second lateral seems too slender judged from my observation on the material of comPt"s at hand and the position of the inner wing seems inappropriate. As a whole his figures of the radula seem somewhat inaccurate. In conclusion, I think think that boninenSis is a synonyrn of eomPtnts. Isao Taki (1938) described comPtzts in detail based on material from Mutsu Bay, with notes on the known localities and distribution. It was followed by the description of L Paztlitlzgs, n. sp., with remarks on the relation to melinvas, mitsz-eleztrii and boninensis, all ef them previously known frorn Japan. In this paper his view to place comPtzes and bofzinensis' collaterally is well shown, and the same treatment is seen in all his later works (1947, 1950, 1954, 1960. 1962), followed by many authors of icono- graphs and catalogues of Japan. Leloup (1941) deScribed I. comPtzvs based on specimens from Misaki, in his paper on Ischnochiton species frem Tsingtao, China; concerning "les the girdle sca}e he says that jeunes 6cailles pr6sentent des c6t6s longitudi'nales bien marqu6es," and also gives some comments on thaanztmi and boninensis, that both of them are closely allied to comPtzfs, but witheut any decision about the specific distinction of these species from comPtz-s. I have been somewhat sceptical about Isao Taki's treatment on the above species since 1933, because; outline of comPtigs (1) While the the shell-plates in is ellipsoid and in boninensis elongate ellipsoid, this character is not constant and it is nearly impossible to distinguish comPtzfs of elongate shell-plates from boninensis of short shell-plates. The sculpture of shell-plates is also quite variable and cannot be a proper criterion of discrimination. (2) He says that posterior area of the tail-valve is wider in boni- nensis while it is narrower in cemPtus, but this distinction is not so clear-cut among numerous specimens. (3> These two species cannot be discriminated by the form of the NII-Electronic Library Service The malacologicalsocietymalacological society of Japan TAKI:ChitonFaunaof Japan (1) 345 t ttt tt / ,.. 't/' -,:',"i ttttt i. /.--,,'Ll- /' .lt/1('-' /1',1 L;'I,Itlll'f,,.,1' ,,･ ･ g.1.,,/-i,,g.･,-1,･ -l-l,',,,lt,{ ,. -, 1.1.ll, .-, Z･･ -'"T.'','t tE }i.'i･--.'-. t-･{'. t... .,. i,,/-,',i?,･-/･.',･-;t-;-,ttt,,.･.S///L,', rw- .M t.!., twes ','1･rv. ',i'-' it' e.;it.･.X. - tt･iifl.rtt'/,･..,ag :-.t;II;. ifl- tt,t'･ .L･-fX･t Text-figs. Dorsal views of (1) Ischnochiton comPt"s f. comPtus s.str. Length ef largest specimen, 24mm. Loc. Mitsune-mura, Hachij6 Island; (2) L comPtus f.isaoi, form. nov. 23.8mm. Loc. Hayarna. Kanagawa Pref. radula. (4) The range of distribution of these two species agrees with the exception in the northern and southern regions.