Amynthas dispersus Sun & Qiu, 2018

Sun, Jing, Jiang, Ji-Bao, Bartlam, Scott, Qiu, Jiang-Ping & Hu, Feng, 2018, Four new Amynthas and Metaphire earthworm species from nine provinces in southern China, Zootaxa 4496 (1), pp. 287-301 : 288-291

Amynthas dispersus Sun & Qiu , sp. nov.

( Figure 2 )

Type material. Holotype: One clitellate (C-GD 201108 -07A) specimen , China, Guangdong Province, Heishiding Natural Reserve (23°27'51"N, 111°54'57"E), 192 m asl, topsoil below shrubs in broad-leaved dominant subtropical/seasonal rainforest, lateritic red soil, 12 Oct. 2011, J. B. Jiang, J. Sun, J. X. Li and L. Zhang coll. Paratypes: A total of 21 specimens, as follows: Two clitellates (C-GD 201108 -07B) , same data as for holotype. One clitellate (C-GD 201108 -09) , same data as for holotype. One clitellate (C-GD 201108 -11) , same data as for holotype. One clitellate (C-GD 201108 -12) , same data as for holotype. One clitellate (C-GD 201108 -16) , same data as for holotype. Two clitellates (C-GD 201108 -19) , same data as for holotype. One clitellate (C-GD 201109 -06) , China, Guangdong Province, Heishiding Natural Reserve (23°27'51"N, 111°54'52"E), 184 m asl, in broad-leaved dominant subtropical/seasonal rainforest, sandy lateritic red soil, 13 Oct. 2011, J. B. Jiang, J. Sun, J. X. Li and L. Zhang coll. One clitellate (C-GX 201212 -06) , China, Guangxi Province, Huaping National Natural Reserve (25°32'28"N, 109°58'22"E), 1303 m asl, topsoil below shrubs in evergreen broad-leaved dominant subtropical forest, yellow soil, 12 Jun. 2012, J. B. Jiang, X. Sun and C. Zhao coll. Two clitellates (C-GX 201214 -04) , China, Guangxi Province, Huaping National Natural Reserve (25°32'44"N, 109°58'36"E), 973 m asl, topsoil below shrubs and bamboo in Mid-subtropical evergreen broad-leaved forest, yellow soil, 13 Jun. 2012, J. B. Jiang, X. Sun and C. Zhao coll. One clitellate (C-GX201312-01) , China, Guangxi Province, Dayaoshan National Natural Reserve (23°58'22"N, 110°06'40"E), 1210 m asl, topsoil below bamboo in Mid-subtropical evergreen broad-leaved forest, sandy yellow soil, 15 May 2013, J. P. Qiu, Y. Hong, J. B. Jiang, L. L. Zhang and Y. Dong coll. One clitellate (C- GX201313-01) , China, Guangxi Province, Dayaoshan National Natural Reserve (23°58'20"N, 110°06'44"E), 1353 m asl, topsoil below bamboo in Mid-subtropical evergreen broad-leaved forest, sandy yellow soil, 15 May 2013, J. P. Qiu, Y. Hong, J. B. Jiang, L. L. Zhang and Y. Dong coll. One clitellate (C-GX201321-06) , China, Guangxi Province, Jiuwanshan National Natural Reserve (25°11'57"N, 108°47'44"E), 404 m asl, in Mid-subtropical evergreen broad-leaved forest, sandy yellow soil, 18 May 2013, J. P. Qiu, J. B. Jiang, L. L. Zhang and Y. Dong coll. One clitellate (C-GX201601-09) , China, Guangxi Province, Maoershan National Natural Reserve (25°51'25"N, 110°29'36"E), 813 m asl, topsoil below arbor, shrub and fern in Mid-subtropical evergreen broad-leaved forest, yellow soil, 4 Jun. 2016, J. Sun, Y. Zheng and X. Gong coll. Three clitelates (C-GX201601-02) , China, Guangxi Province, Maoershan National Natural Reserve (25°51'25"N, 110°29'36"E), 813 m asl, topsoil below arbor, shrub and fern in Mid-subtropical evergreen broad-leaved forest, yellow soil, 4 Jun. 2016, J. Sun, Y. Zheng and X. Gong coll. One clitellate (C-GX201602-05) , China, Guangxi Province, Maoershan National Natural Reserve (25°49'57"N, 110°27'43"E), 531 m asl, topsoil below arbor, shrub, fern and bamboo in Mid-subtropical evergreen broad-leaved forest, yellow soil, 4 Jun. 2016, J. Sun, Y. Zheng and X. Gong coll. One clitellate (C-GX201603-01) , China, Guangxi Province, Maoershan National Natural Reserve (25°40'27"N, 110°29'02"E), 223 m asl, topsoil below arbor, shrub, fern and bamboo in Mid-subtropical evergreen broad-leaved forest, yellow soil, 4 Jun. 2016, J. Sun, Y. Zheng and X. Gong coll.

Etymology. The Latin dispersus means dispersed; the name refers to the species’ comparatively broad distribution range.

Diagnosis. Medium-sized species; four pairs of spermathecal pores in 5/6–8/9; male pore porophore elliptical and glandular, raised on a low pad-like area, surrounded by two to three shallow skin folds; genital papillae variable and present in spermathecal pore and male pore regions; prostate gland vestigial or rudimentary; spermathecal diverticulum about as long as main spermathecal axis, and distal half dilated into band-shaped seminal chamber.

Description. External characters. Preserved specimens brown on dorsum and lacking pigment on ventrum. Mid-dorsal line pigmented posterior to clitellum. Dimensions 75–110 mm by 2.2–3 mm at clitellum, segment number 91–97. No secondary annulations. Prostomium ½ epilobous. First dorsal pore in 10/11 or 11/12. Clitellum annular in XIV–XVI, smooth, swollen, no setae on ventral side, dorsal pores usually absent on clitellum. Setal counts, however, are not significantly different. Satae uniformly distributed, 24–28 at III, 2 4–28 at V, 28–34 at VIII, 30–42 at XX, 32–38 at XXV; 8– 9/VI, 10/VII, 10/VIII between spermathecal pores, 6–8 between male pores, setal formula AA=1.2–1.8AB, ZZ=1.3–2ZY. Spermathecal pores four pairs, in 5/6–8/9, intersegmental, about 0.33 of circumference ventrally apart ( Fig. 2A ). A pair of small genital papillae anterior to the left and right setae A in IX for holotype; one to four small genital papillae present on the ventral side of VIII–X randomly for paratypes. Male pores in XVIII a little less than 0.33 of circumference ventrally apart, elliptical and glandular raised porophore on a low pad-like area, surrounded by two to three shallow skin folds, ventral furrows 17/18 and 18/19 nearly obscured by tumescence. Male pore papillae variable, holotype with two small, round papillae in front of seta A on XVIII ( Fig. 2B ). Paratypes, one to three small round papillae anterior to the segmental equator in XVII– XX ventrally and randomly. Female pore single mid-ventral in XIV, milk-white, elliptical, slightly swollen.

Internal characters. Septa 8/9–9/10 absent, 5/6–6/7 thickened and muscular, 7/8 and 10/11–14/15 thicker than those following. Dorsal blood vessel single, continuous onto pharynx; esophageal hearts four pairs in X–XIII, the first pair slimmer than the others. Gizzard bucket-like, in VIII–X; intestine swelling in XVI; intestinal caeca simple, originating in XXVII and extending forward to XXV, finger-shaped sacs, tiny incisions present on dorsal and ventral margins. Male organs: Testis-sacs in X and XI; oval, moderately developed, two lobes slightly separated ventro-medially. Seminal vesicles in XI, XII, developed, both separated ventro-medially. Prostate gland completely vestigial in holotype but right lobe present in XVIII–XIX (small, rudimentary) in paratype C- GX201601-09, its duct in XVIII, symmetrically S-shaped ( Fig. 2C ). No visible accessory glands on XVIII. Female organs: Spermathecae paired in VI–IX, about 3 mm long; ampulla heart-shaped, distinctly marked off from its duct, duct as long as ampulla; diverticulum about as long as main spermathecal axis, distal half dilated into bandshaped seminal chamber; no nephridia on spermathecal ducts ( Fig. 2D ).

DNA barcodes. GenBank accession numbers KF205408 (C-GD 201108 -07A, holotype), KY774372 (C- GX201601-09, paratype), KY774373 (C-GX201601-02, paratype), KY774374 (C-GX201602-05, paratype), KY774375 (C-GX201603-01, paratype).

Remarks. Amynthas dispersus sp. nov. keys to the Amynthas corticis group ( Sims & Easton 1972). This group is diagnosed by four pairs of spermathecal pores intersegmental in 5/6–8/9 and a holandric male sexual system ( Sims & Easton 1972).

The new species is somewhat like the cosmopolitan species Amynthas corticis (Kinberg, 1867) in the following characteristics: (1) medium-sized body; (2) dark pigment (but not green) on dorsum and pale or no pigment on ventrum; (3) the numbers of setae increases posteriorly; (4) four pairs of spermathecal pores in 5/6–8/9; (5) intestinal caeca simple with smooth margins; (6) prostate glands often aborted. However, there are several differences: (1) the male pore of the new species is a glandular, raised porophore on a low pad-like area, whereas in A. corticis the male porophore is on a depressed corny pad; (2) one to four spermathecal pore region genital markings are normally located mid-ventrally in VIII–X in the new species, but are close and medial to the spermathecal pore in A. corticis ; (3) one to three male pore region papillae are mid-ventral and near setae AA in the new species, but absent or present, and if present, one or two medial to male pores in A. corticis ; (4) diverticulum seminal chamber is band-shaped for the new species, but spherical bulb or blunt oval for A. corticis .

The new species also resembles A. homosetus ( Chen, 1938) , initially collected from Hainan Island, China in some of its characteristics, such as four pairs of spermathecal pores in 5/6–8/9, glandular male pore porophore and simple intestinal caeca, but it differs from A. homosetus in having variable genital markings always present in the spermathecal pore and male pore regions, the prostate gland is usually vestigial, and the diverticulum seminal chamber is band-shaped in the new species ( Chen 1938).

All known species in nearby locations, including Southeast and East Asia, were also checked. However, only one South Korean earworm species, Amynthas sangumburi Hong & Kim, 2002 appears similar to the new species in the number and position of spermathecal pores and glandular male pores, but it has significant differences in genital markings, prostate glands and diverticulum ( Hong & Kim 2002). In addition, the known populations of the two species are geographically separated by more than 4000 kilometers.

Figures

FIGURE 2. Amynthas dispersus sp. nov. A. Spermathecal pores (sp) and genital papillae (gp). B. Male pores (mp) and genital papillae (gp). C. Prostate gland. D. Spermatheca.