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ムネマルミミズ Amynthas surculatus Azama & Ishizuka, 2018
Amynthas surculatus Azama & Ishizuka, 2018: 25.
基産地:西銘岳(沖縄県)(26°48′12′′N, 128°16′22′′E, 320 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-00013)
パラタイプ 琉球大学資料館(風樹館)(RUMF-ZO-00014〜17)
<外部形態>
全長 60-90 mm、体幅 第13体節で 2.8–3.5 mm。体節数 91-115。
体色は、生体は背面は暗褐色で、腹面は明褐色、環帯は暗褐色。
剛毛は、第 7 体節で 40-54 本、第 20 体節で 45-52 本。
受精囊孔は 2 対で、第 5/6/7 体節間溝で、受精囊孔間距離は体周の約1/3。性徴は第 7-8 体節の腹面中央の剛毛線より後ろに、大きな円形の吸盤状性徴を持つ。第一背孔は第 11/12
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、突起型。雄性孔間距離は、体周の約 1/3。雄性孔間の腹面は強く陥没する。雄性孔間剛毛は 8-11 本。
<内部形態>
隔膜は第 8/9/10 体節間で欠き、第 5/6/7/8 体節間で厚く、第 10/11/12/13/14 体節間でやや厚い。
受精囊は第 6-7 体節に 2 対で、主嚢は大きくて桃型で、嚢状部と導管がほぼ同長。副嚢の嚢状部は楕円形で、細い導管を持つ。生殖腺は第 7-8 体節(稀に第 6-8 体節)にあり、泡状で大きな円形。貯精嚢は大きく、第 11–12 体節まで広がる。摂護腺は第18体節にあり、第 17-20 体節まで広がり、U字型の導管を持つ。
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 3–4 体節、前方に伸びる。
Diagnosis. Two pairs of spermathecal pores in furrows 5/6/7. Male pores superficial at large sucker shaped porophore on segment
18. Genital markings single, large circular sucker shape at mid-ventral line, post-setal of segments 7–8. Simple intestinal caeca, originating in segment 27.
Material examined. Holotype (RUMF-ZO-00013): collected from litter and humus soil under the natural forest dominated by Castanopsis
sieboldii, nearby Mt. Nishime-dake, Kunigami Village, Okinawa-jima Island, southwestern Japan, 26°48′12′′N, 128°16′22′′E, 350 m a.s.l., 15-II-1999, collected by Y. Azama and K. Ishizuka.
One paratype (RUMF-ZO-00014): collected from same locality as holotype, 7-XII-2014, by Y. Azama. Three paratypes (RUMF-ZO-00015–17): same data as the holotype.
Description. Measurement and color: Body length 60–90 mm, width 2.8–3.5 mm in segment 13. Number of segments 91–115.
Dark-brown dorsally, light-brown ventrally, dark-brown clitellum.
External characters: Two pairs of spermathecal pores situated in furrows 5/6/7, in ventro-lateral sides, separated by a distance of ca.
1/3 body circumference. Genital markings single, large circular sucker shape, situated on mid-ventral line, post-setal on segments 7–8, occasionally segments 6–8 in pre-clitellar,
absent in post-clitellar. First dorsal pore beginning in furrow 11/12. Clitellum oocupying segments 14–16. Female pore single, mid-ventrally on segment 14. Male pore
paired in segment 18, simple, superficial, separated by a distance of ca. 1/3 body circumference. Setal number 40–54 in segment 7, 45–52 in segment 20, 8–11 between male pores.
Internal characters: Two pair spermathecae situated in segments 6–7; ampulla large and peach-shape, duct almost equal in length of
ampulla; diverticulum with slender duct and oval-shaped chamber. Genital glands situated in segment 7–8 (occasionally segments 6–8), glandular masses type, large round shape, associated
with the genital markings restricted to body wall. Septa absent in 8/9/10 thickened in 5/6–7/8 and slightly thickened in 10/11–13/14. Seminal vesicles large, extending to the
dorsal line in segments 11–12. Intestine begins in segment 15. Prostate glands pairs in segment 18, extending through segment 17–20, U-shaped long duct associated with male pores.
Simple intestinal caeca paired, originating in segment 27, extending anteriorly for 3–4 segments.
Etymology: The specific epithet “surculatus” in Latin word means “sucker”. This name refers to the morphological characteristics
of this species which has large circular sucker-shaped genital markings in pre-clitellar.
Remarks. The new species is distinguishable from the other congeneric species which shared morphological characteristics such as two
pairs of spermathecal pores in furrows 5/6/7 and simple intestinal caeca, by single large circular sucker-shaped genital markings, at mid-ventral line post-setal on segments 7–8 (occasionally
6–8) in pre-clitellar (Chang et al., 2009; Chen, 1931, 1933, 1935, 1936, 1938, 1936; Chen et al., 1975; Gates, 1935, 1972; Ishizuka, 2001, 2015; Ishizuka and Minagoshi, 2014).
沖縄本島の西銘岳の近くに分布する (Azama & Ishizuka, 2018)。
種小名の surculatus は、ラテン語で吸盤の意。本種が環帯より前に大きな吸盤状の性徴を持つことから命名された。
Amynthas surculatus Azama & Ishizuka, 2018: 25 ムネマルミミズ (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)