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ヒョウタンミミズ Amynthas cucurbitae Azama & Ishizuka, 2018
Amynthas cucurbitae Azama & Ishizuka, 2018
基産地:西銘岳付近(沖縄県)(26°48′12′′N, 128°16′22′′E, 340 m a.s.l.)
タイプ標本所在地:ホロタイプ 琉球大学資料館(風樹館)(RUMF-ZO-00021)
パラタイプ 琉球大学資料館(風樹館)(RUMF-ZO-00022〜26)
<外部形態>
全長 53–74 mm、体幅 第13体節で 2.6–3.1 mm。体節数 79–102。
体色は、背面は紫褐色で、腹面は明黄灰色、環帯は暗褐色。
剛毛は、第 7 体節で 24–28 本、第 20 体節で 28–34 本。
受精囊孔は 4 対で、第 5/6/7/8/9 体節間溝で、受精囊孔間距離は体周の約1/4。受精嚢孔に接して粒状の外部表徴を持つ。第一背孔は第 12/13
体節間溝。環帯は第 14–16 体節。雌性孔は第 14 体節の腹面中央に一つ。雄性孔は第
18 体節に1対あり、突出型。雄性孔間距離は、体周の約 1/4。雄性孔の周りに、ひょうたん型の有色彩紋があり、第17体節の剛毛線より後ろから第19体節の剛毛線より前まで広がる。雄性孔間の腹面は強く陥没する。雄性孔間剛毛は 3–4 本。
<内部形態>
隔膜は第 8/9/10 体節間で欠き、第 5/6/7/8 体節間と第 10/11 体節間で厚い。
受精囊は第 6–9 体節に 4 対で、主嚢はシャベル型で、短い導管を持つ。副嚢の嚢状部はソーセージ型で、導管を持つ。生殖腺を欠く。貯精嚢は小さく、第 11–12
体節まで広がる。摂護腺は第18体節にあり、第 16–21 体節まで広がり、捻れた導管を持つ。
腸は第 15 体節から始まる。腸盲嚢は単純型で、第 27 体節から 2–3 体節、前方に伸びる。
Diagnosis. Four pairs of spermathecal pores in furrows 5/6/7/8/9. Male pores simple, superficial on segment 18. Gourd-shaped colored patch types external markings (genital glands absent),
close to male pores, on segment 17¬–19. Simple intestinal caeca, originating in segment 27.
Material examined. Holotype (RUMF-ZO-00021): collected from humus soil under the natural forest dominated by C. sieboldii, nearby Mt. Nishime-dake, Kunigami Village, Okinawa-jima Island,
26°48′12′′N, 128°16′22′′E, 340 m a.s.l., 18-XII-1998, by Y. Azama and K. Ishizuka. Five paratypes (RUMF-ZO-00022–26): same data as the holotype.
Description. Measurement and color: Body length 53–74 mm, width 2.6–3.1 mm in segment 13. Number of segments 79–102. Purplish-brown dorsally, light yellowish-grey ventrally, dark-brown
clitellum.
External characters: Four pairs of spermathecal pores situated in furrows 5/6/7/8/9, in ventro-lateral sides, separated by a distance of ca. 1/4 body circumference. Genital markings absent,
but two types external markings (genital glands absent) paired, one is granular and it contacts each spermathecal pores in pre-clitellar; another one is large gourd-shape colored patch types,
close to male pores, extending from post-setal on segment 17 to pre-setal on segment 19 in post-clitellar. First dorsal pore beginning in furrow 12/13. Clitellum occupying segments 14–16.
Female pore single, mid-ventrally on segment 14. Male pores paired, superficial on segment 18, separated by a distance of ca. 1/4 body circumference. Setal number 24–28 in segment 7, 28–34 in
segment 20, 3–4 between male pores.
Internal characters: Spermathecae four pairs in segment s 6–9; ampulla consisting of a shovel-shaped pouch and a short duct; diverticulum consisting of a sausage-shaped pouch and a duct.
Genital glands absent. Septa absent in 8/9/10, thickened in 5/6/7/8 and 10/11. Seminal vesicles small, extending in segments 11–12. Intestine begins in segment 15. Prostate extending through
segments 16–21, twisted duct associated with the male pores. Simple intestinal caeca paired, originating in segment 27, extending to anteriorly for 2–3 segments.
Remarks: The new species is distinguishable from the other congeneric species which shared morphological characteristics such as four pairs of spermathecal pores in furrows 5/6/7/8/9 and
simple intestinal caeca, by large gourd-shaped colored patch type external markings (genital glands absent) close to male pores and extend from post-setal on segment 17 to pre-setal on
segment 19 in post-clitellar (Chang et al., 2009; Chen, 1931, 1933, 1935, 1936, 1938, 1946; Chen et al., 1975; Gates, 1935, 1972; Ishizuka, 2001, 2015; Ishizuka and Minagoshi, 2014).
Etymology: The specific epithet “cucurbitae” in Latin word means “gourd”. This name referes to the morphological characteristics of this species which has gourd-shaped external markings
closed to male pores.
沖縄本島の西銘岳付近に分布する (Azama & Ishizuka, 2018)。
種小名の cucurbitae は、ラテン語でヒョウタンの意。雄性孔に接してひょうたん型の外部表徴を持つことから命名された。
Amynthas cucurbitae Azama & Ishizuka, 2018: 29 ヒョウタンミミズ (新称). [形態記載] (Nov 30,
2018)
Azama, Y., Ishizuka, K., 2018. Three new earthworm species of the
genus Amynthas (family Megascolecidae) from northern mountainous part of Okinawa-jima Island, Japan. Edaphologia 103: 25-32. (Nov. 30, 2018)