ヒョウリュウミミズ

　フトミミズ科＞アズマフトミミズ属＞ヒョウリュウミミズ Amynthas bidenryoanus (Ohfuchi, 1956)

Pheretima houlleti var. bidenryoana Ohfuchi, 1956: 169.

Amynthas bidenreyoanus [sic] Sims & Easton, 1972: 237.

Pheretima houlleti var. bidenryyoana [sic] Ishizuka, 1999a: 60.

Pheretima houlleti 上平, 1973a: 58.

タイプ標本

基産地：鳩間島、西表島祖納のBidenryo

タイプ標本所在地：不明（紛失？） (Reynolds & Cook, 1976)

形態

＜外部形態＞

　全長 70-85 mm、体幅 2.5-3.5 mm、体節数 73-85.

　フォルマリン液浸標本では、体色は背面で褐色、腹面でより明色。

　剛毛は第 7 体節で 42 本、第 20 体節で 51 本。第一背孔は第 12/13 体節間溝もしくは第 13/14 体節間溝。

　環帯は第 14-16 体節の 3 体節を占め、背孔や体節間溝、剛毛を欠く。雄性孔は第 18 体節の剛毛線上にあり、雄性孔間距離は体周の約 1/3。雄性孔間剛毛は 13-14 本。雄性孔の縁は体表からやや盛り上がる。雄性孔に近接してやや内側の剛毛線より後方に 1 対の性徴があり、その直径は 0.3-0.5 mm。受精囊孔は 3 対で、第 6/7/8/9 体節間溝。受精囊孔域に性徴はない。

＜内部形態＞

　隔膜は、第 6/7/8/9 体節間では厚く、第 9/10 体節間では欠き、第 10/11/12/13 体節間ではやや厚い。

　腸管は第 15 体節から開始し、腸盲嚢は突起状型で小突起はなく、第 27 体節から第 23 体節まで伸びる。

　受精囊は第 7-9 体節にあり、主嚢は長さ 2 mm、幅 1.8 mm、導管は約 1 mm。副嚢の先端は棍棒状で、導管はとても長い。精巣は小さく、第 10-11 体節。貯精嚢はよく発達し、第 11-12 体節。卵巣は第 14 体節。摂護腺はよく発達して、第 14-20 体節までの 7 体節分を占める。摂護腺の導管は短く、U 字型に曲がる。交接嚢を欠く。

＜原記載（クリックして展開）＞

Locality: Hatoma and Bidenryo of Sonai, Iriomote. Collected by expedition members to this Island conducted by Dr. Yamashina on April 1, 1936.

External characters: The body length from 70-85 mm. The greatest diameter from 2.5-3.5 mm. The number of segments varies from 73-85.

The colour in formalin, dorsally brownish and ventrally lighter than the dorsal. The prostomium epilobous. Clitellum is annular and extends from XIV to XVI without dorsal pore, intersegmental furrows and setae.

The setae beginning on segment II. The setal numbers are 30/V, 34/VI, 42/VII, 45/VIII, 51/XX.

The first dorsal pore in XII/XIII or in XIII/XIV.

Three pairs of spermathecal pores are in VI/VII, VII/VIII and VIII/IX, ventrolateral in position. No genital papillae in this region.

One pair of genital papillae is round-shape, about 0.3 or 0.5 mm. near to the ventromedian line and is close to the male pores and at the posterior of the setal line.

The male pores situated on setal circle on lateral border of XVIII, about one-third of circumference apart, separated by 13 or 14 setae. The margin of the porophore is somewhat elevated over the body surface.

Internal characters: Septa VI/VII, VII/VIII and VIII/IX thickened, IX/X absent, X/XI, XI/XII and XII/XIII slightly thickened.

Intestine begins in XV, intestinal caeca simple and originating in XXVII and extending anteriorly into about XXIII, without serriformed out-growth in ventral and dorsal margins.

Three pairs of spermathecae situated in VII, VIII and IX. Ampulla smooth and slightly flattened dorso-ventrally and about 2 mm in length, 1.8 mm in breadth and continuous to the duct about 1 mm in length. The spermathecal diverticulum usually arises from the inner face of the spermathecal duct. The diverticulum ends simple staff-like a appearance and the stalk is very long. One roted at the root of the duct of spermathecae.

The ovisac presence in segment XIV. The prostate gland well developed extended from XVI anteriorly and to XX posteriorly. The muscular duct is comparatively short and bends into U-shape.

The seminal vesicles well developed in XI and XII, the dorsally meeting one another and enclosed within hearts and half of the gizzard. Testis sacs small, two pairs in X and XI.

Remarks: Perrier recorded in his paper, with reference to Pheretima houlleti that grape-like glands are situated in segment VII, and the duct extends forwards to open into the oesophagus at the level of VI/VII, but these seems to be blood-glands such as are found in some other species of the genus. Unfortunately I do not know this glands.

Gates described that the copulatory chambers are small but project slightly into the coelom in Pheretima houlleti. According to this chamber Stephenson states that a considerable copulatory sac which; appears as a porophore when everted. It seems to me that this chamber is sure very lower in development, but unfortunately I did not find such chamber in this species, accordingly established as new variety distinct from Pheretima houlleti.

分布

　タイプ標本が得られて以降、採集記録は全く無い。タイプ標本は先島諸島の西表島、鳩間島で得られている (Ohfuchi, 1956)。

備考

　タイプ産地として、鳩間と西表島祖納の Bidenryo が挙げられている。Bidenryoが何を指すのか不明であるが、美田良（みたら／みだら）と何らかの関係があるかも知れない (南谷, 私見)。

　Ohfuchi (1956) は M. houlleti の変種として本種を記載したが、Gates (1972a) は M. houlleti の形態変異の範囲内には入らないとして独立種とし、Sims & Easton (1972) はフクロフトミミズ属 Metaphire である houlleti とは異なるアズマフトミミズ属 Amynthas とした。その後、Easton (1981) は疑問符付きで、Blakemore (2003, 2008d) は括弧と疑問符付きでコンジキミミズ A. flavescens のシノニムとした。なお、Blakemore (2012b) は疑問符無しでコンジキミミズのシノニムとした。

　しかし、M. houlleti ともコンジキミミズとも異なるため、Gates (1972a) や Sims & Easton (1972)、Shen (2018) に従い、独立種とした。

シノニムリスト

Pheretima houlleti var. bidenryoana Ohfuchi, 1956: 169. [形態記載]

Amynthas bidenreyoanus [sic] Sims & Easton, 1972: 237. [記述のみ]

Pheretima houlleti 上平, 1973a: 58. [同定形質のみ] (?, 1973)

Pheretima houlleti var. bidenryyoana [sic] Ishizuka, 1999a: 60. [記述のみ]

引用文献

Blakemore, R.J., 2003. Japanese earthworms (Annelida: Oligochaeta): A review and checklist of species. Organisms Diversity and Evolution 11: 1-43.

Blakemore, R.J., 2008d. A review of Japanese earthworms after Blakemore (2003). In: Ito MT, Kaneko N, (eds.), A Series of Searchable Texts on Earthworm Biodiversity, Ecology and Systematics from Various Regions of the World, 2nd Edition (2006) and Supplemental. COE soil Ecology Research Group, Yokohama National University, Japan. CD-ROM Publication.

Blakemore, R.J., 2012b. Japanese earthworms revisited a decade on. Zoology in the Middle East 58 suppl 4: 15-22.

Easton, E.G., 1981. Japanese earthworms: A synopsis of the Megadrile species (Oligochaeta). Bulletin of the British Museum Natural History (Zoology) 40(2): 33-65.

Gates, G.E., 1972a. Burmese earthworms- An introduction to the systematics and biology of megadrile oligochaetes with spacial reference to southeast Asia. Transactions of the American Philosophical Society 62(7): 1-326.

Ishizuka, K., 1999a. A review of the genus Pheretima s. lat. (Megascolecidae) from Japan. Edaphologia (62): 55-80.

上平幸好, 1973a. 日本産陸棲貧毛類フトミミズ属(Genus Pheretima), 種の検索表. 函館大学論究 7: 53-69.

Ohfuchi, S., 1956. On a collection of the terrestrial oligochaeta obtained from the various localities in Ryu-Kiu Islands, together with the consideration of their geographical distribution (Part 1). Journal of Agricultural Science, Tokyo Nogyo Daigaku 3(1): 131-176.

Shen, H.P., 2018. Biogeography meets taxonomy: Distribution-based inferences on the accuracy of identification and synonymization of East Asian earthworms. Zootaxa 4496(1): 313–336.

Sims, R.W., Easton, E.G., 1972. A numerical revision of the earthworm genus Pheretima auct. (Megascolecidae: Oligochaeta) with the recognition of new genera and an appendix on the earthworms collected by the Royal Society North Borneo Expeditions. Biological Journal of the Linnean Society 4: 169-268.