オオフナトジュズイミミズ

＜原記載（クリックして展開）＞

 

External charasters

　　The measurements of the body length and body width in the average of 10 specimens from Ofunato are as follows:

　　The body length varies from 228-283 mm, 251 mm in average, the width at segment X varies from 5-6.5 mm, 6 mm in average.

　　The measurements of the number of segments varies from 189-242, giving 224 in average.  Length of segments taken from a specimen, is as follows; IV- 1.3 mm, V- 1.8 mm, VI- 2 mm, VII- 2 mm, VIII- 2 mm, IX- 1.8 mm, X- 2.4 mm, XI- 2.4 mm, XII- 1.6 mm, XX- 1.2 mm, last ninth segment - 0.5 mm.

　　The colour is yellowish dark on the dorsal surface, yellowish grey on the ventral surface, clitellum similar to ventral surface, and sometimes the anterior-most portion of the body is pointed which is brownish-green.  Dorsal pores lacking.

　　Clitellum occupies 4 segments, X-XIII, first clitellum gradually becoming larger in diameter (Text-fig. 3), glandular part appearing swollen, distinctly distinguished from other segments.  Such features have not been seen in the other species of the genus.

　　The spermathecal openings is of one pair in VII/VIII, longitudinal slits of eye-shape, in which are found minute and round-shape openings, as shown in Text-fig. 2, 1.

　　Nephridiopores very minute at anterior edge of every segment close to intersegmental furrow, along latero-ventral lines or slightly lateral.

　　The genital papillae are round in shape and 0.6-0.7 mm in diameter.  These are confined to the segments situated at the male and spermathecal regions VII-XIII, their distribution seems to be relatively regular, having one to three pairs in number, but sometimes only a few; they are whitish or pale in colour, slightly elevated from the body surface, and are associated with the glandular mass internally.

　　Setae very small, hardly visible, due to being embbeded into epidermis which is velvet, and appearing as black pits under magnification, setae beginning on II, absent or first one and last some segments, uniformly built on remaining segments, aa always wider than bc in each segment; aa on XI-XV, becoming markedly wider than bc, under XVI gradually restored to the former condition.  ab=cd, dd nearly equal to 7/10 of circumference, on spermathecal region, and dd nearly equal to 7/10 of circumference, on clitella region.  And in the middle portion, dd nearly equal to 6/10 of circumference of segment.  Each seta sigmoid, curved at both ends in a weak S-shape, external free end often abruptly curved backward as a hook or sometimes gently curved, its large part embbeded in body wall.  About 528 microns in length, 28 microns in width.

　　Male pore, on pair of large transverse slits in X/XI, about 1.5 mm in transverse length, 0.7 mm in width between bc, about 1/5 nearer to b, the secondary male pore with a disc-shaped penis is usually not visible externally; well delineated protuberant just as the lips which formed by epidermal thickening of both posterior and anterior margins of X and XI, and those lips in most cases are closely shut, about 2 mm in transverse diameter, 5-6 mm in width.

　　Female pore one pair, in XI/XII, in ab line, transverse slits minute hardly visible.

 

Internal characters

　　Spermathecal ampulla one pair, approximately round and large, about 4.8 mm long, 3 mm broad, its duct about 10.5-11 mm long.  This long duct arising from the lower side of the ampulla, enters into the body wall, attaching to septum of VII/VIII, whitout atrium, always situated in VII.

　　Testis sacs one pair in XI, suspending on posterior faces of septa X/XI, pushed anteriorly in small part of preseding segment; very large middle part constricted, about 3.3 mm in length of long axis, 2 mm in width, with thick and tough wall, surface dull yellowish or pale and shiny, internally filled with spongy tissue and small amount of seminal mass embbeded in the matrix; testis and seminal funnel lying on anterior ventral side of the sac.  Vas defferens merging from ventral side of testis sac, making coils, and the duct are wrapped up with membrane, penetrating the septum into preceding segment, thrown into coiled mass near ventral body wall and again passing through septum back to unite with a roundish prostate gland (about 3 mm in diameter) through which it passes out as shown in Text-fig. 5, 1.

　　Ovarian chamber in XI, entirely fused in dorsal side and widely separated in ventral side.  Ovaries, one pair, large and placed at anterior of chamber Ovisac, one pair, stretched from dorsal side of XI/XII, and lying on both sides of gizzards.

　　Digestive truct, pharynx with thick muscular wall in III-IV, behind which follows the oesophagus, in V-XI, as a thick walled and narrow tube, gizzard usually four, in XII-XVII, sometimes in XII-XVIII, gizzard brownish or silver in colour, generally smooth and shining on surface.

　　Dorsal blood vessel very large in calibre; not bifurcated anteriorly, blood sinuses appearing behind XVI/XVII; hearts four pairs in VI-IX, connecting both dorsal and ventral vessels; commissural vessels in IX and X, connecting with latero-oesophageal vessels.

　　Pharyngeal glands, moderately bulky and very thick, arranged into thick several transverse layers in III and IV.

　　Nephridia meganephridial type, paired in every segment as other species of the same genus; absent in anterior two and posterior three segments.  Nephridia each consisting of two parts; that is, a very large and transparent vesicle extending from ventral behind each septum to dorsal side or even over-lapping with that from opposite side, about 0.8-1 mm in width, about 4 mm, but if full stretched 7 mm in length; with a small nephrostome and a short thin canal placed in front of septum which is united with a long tubule behind septum.  Septum is much convoluted on under digestive truct on these two parts meeting near ectal end to form a broad and muscular duct to penetrate body wall to external nephridiopore, as shown in Text-fig. 5, 2.  Nephridia vestigeal in X and XI those in VI-IX large.

　　Septum, septa V/VI, VI/VII, VII/VIII and VIII/IX much thickened, IX/X, X/XI and XI/XII more or less thickened, other remaining septa all thin.

 

Remarks

　　In general outline, and in having no spermathecal atrium and male atrium the present species resembles D. nemora Kobayashi, but many other characters easily distinguished that species from the present one.  The setal line is slightly elevated from the body surface, and especially distinct on the cd setal line on the region posterior to clitellum in D. nemora, which in the present one these features are just the opposite.  The position of gizzard, the body length, structures of penis and prostate distinguish these species from one another.