Amynthas gracilis ( Kinberg, 1866 )

Shen, Huei-Ping & Yeo, Darren C. J., 2005, Terrestrial Earthworms (Oligochaeta) From Singapore, Raffles Bulletin of Zoology 53 (1), pp. 13-33 : 21

publication ID	https://doi.org/ 10.5281/zenodo.13244835
persistent identifier	https://treatment.plazi.org/id/0D51326D-B67F-FFE4-9A09-FE3E450495CD
treatment provided by	Felipe
scientific name	Amynthas gracilis ( Kinberg, 1866 )
status

Treatment

Amynthas gracilis ( Kinberg, 1866) View in CoL

Nitocris gracilis Kinberg, 1866: 102 View in CoL . Perichaeta hawayana Rosa, 1891: 396 View in CoL ; Beddard, 1896: 201. Perichaeta bermudensis Beddard, 1892a: 160 View in CoL . Perichaeta barbadensis Beddard, 1892a: 167 View in CoL (part). Perichaeta pallida Michselsen, 1892: 227 View in CoL (part). Perichaeta mandhorensis Michaelsen, 1892: 241 View in CoL . Amyntas mandhorensis – Michaelsen, 1899: 86. Amyntas hawayanus – Beddard, 1900a: 645 (part). Pheretima hawayana View in CoL – Michaelsen, 1900: 271; 1928: 40; Ude, 1905:

457; Stephenson, 1912: 276; Gates, 1936b: 417; 1972: 189. Pheretima mandhorensis – Michaelsen, 1900: 281. Pheretima hawayana (Rosa) View in CoL f. typica – Michaelsen, 1909: 187;

Chen, 1931: 142; 1933: 238; Ude, 1932: 155. Pheretima hawayana var. typica – Gates, 1931: 382; 1932: 433. Amynthas hawayanus – Sims & Easton, 1972: 235. Amynthas gracilis – Sims & Easton, 1972: 235; Easton, 1981: 50

(part); 1982: 728; 1984: 118.

Material examined. – 1 mature (clitellate) specimen (dissected)( ZRC), Kent Ridge Campus of National University of Singapore, coll. P. H. Ho, damaged and given to the senior author on 29 Dec.1999 ; 1 mature and 1 amputated, immature specimens ( ZRC), Rifle Range Rd. opposite to Murnane Reservoir, coll. K. K. P. Lim, D. C. J. Yeo & K. L. Yeo, 25 Jun.2003 .

Description. – Length (mature) 120-127 mm, weight 1.08- 1.15 g. Segments numbering 92-94. Prostomium epilobous. First dorsal pore 10/11 or 11/12. Setal number 30-39 in VII, 54-60 in XX, 14-16 between male pores in XVIII. Clitellum XIV-XVI, 3.0- 3.2 mm in length, 3.95-4.55 mm in width, dorsal pores absent, 6-12 setae on ventral XVI. Spermathecal pores three pairs in 5/6-7/8. Preclitellar genital papillae absent or widely paired, postsetal on VII near 7/8 segmental furrow, one additional postsetal papilla on medio-ventrum of VIII near 8/9 segmental furrow for one mature specimen. Each papilla small, round, about 0.25 mm in diameter. Female pore single, medio-ventral in XIV. Male pores paired in XVIII, 0.31-0.34 body circumferences ventrally apart, each on a small, round porophore surrounded by four or five circular folds. One or two postsetal papillae medial to each male porophore. Each papilla round, centre concave, 0.25-0.4 mm in diameter. Preserved specimens brown or yellowish grey, with grey ventrum and dark brown clitellum.

Septa 5/6-7/8 and 10/11-13/14 thickened, 8/9 and 9/10 absent. Gizzard in IX-X. Intestine enlarged from XIV. Intestinal caeca paired in XXVII-XXV, each simple with small indentations on the edge. Esophageal hearts XI-XIII. Meronephridia bush-like mass in intersegmental spaces anterior to 6/7. Spermathecae three pairs in VI-VIII, ampulla oval, large with a long, stout stalk. Diverticulum long, slender, slightly twist at the end. Holandry: testis sacs paired in X and XI, round, smooth. Seminal vesicles paired in XI and XII, large, posterior pair extending into XIII. Prostate glands paired in XVIII, lobed, extending anteriorly to XVI and posteriorly to XXI. Prostatic ducts large, U-shaped. Accessory glands stalked.

Remarks. – Amynthas gracilis is a holandric and sexthecal earthworm belonging to the gracilis ( = hawayanus ) species-group of the genus Amynthas (sensu Sims & Easton, 1972) . According to Gates (1972) it is native to China, and was introduced to Hawaii and California before 1852. It is a cosmopolitan species, and has often been confused with Amynthas morrisi (see Gates, 1968).

Two nominal species, Amynthas pallidus (Michselsen, 1892) and Amynthas barbadensis (Beddard, 1892) , are actually mixtures of specimens of A. gracilis and A. morrisi based on the original descriptions of individual specimen: the two type specimens of A. pallidus are in fact an A. gracilis specimen and an A. morrisi specimen; and the three type specimens of A. barbadensis consist of one A. gracilis (designated as individual b in original description) specimen and two A. morrisi (designated as individuals a and c in original description) specimens.

The differences between A. gracilis and A. morrisi are presented in the Remarks section of A. morrisi .