Amynthas ammalinei Hong and James, 2024

Hong, Yong, Inkhavilay, Khamla & James, Samuel W., 2024, Three new earthworms of the Amynthas corticis-group (Clitellata: Megascolecidae) from the Nam Et-Phouleoi, Laos, Zootaxa 5405 (2), pp. 273-280 : 274-276

Amynthas ammalinei Hong and James sp. nov.

( Fig. 2 )

Material examined. Holotype: 1 clitellate ( BDNUL 0056 ): Laos, Houaphanh Province, Viengthong District, Nam Et-Phouleoi NPA, Thad Ang waterfall area , 792 m (20°15.446ʹN, 103°08.921′E), good forest condition with big trees, dark soil, and thick litter layer, July 21, 2005; Phimphet, Xay, Ammaline, Phoang, and K. Inkhavilay. Non-types: 1 clitellate, 1 aclitellate, same data as for holotype.

Etymology. The species is named after Mr. Ammaline, one of the collectors.

Diagnosis. Four pairs of spermathecal pores in 5/6–8/9 at 17 th setal line; male pores superficial on small round porophores at lateral margins of ventrum, 0.16–0.31 circumference apart, segments I and II fused, caeca manicate, additional manicate caeca in XXVIII, XXIX.

Description. Dimensions 40–44 mm by 2.5–3.7 mm at segment X, 2.5–3.2 mm at segment XXX, 3.0–4.0 mm at clitellum; body cylindrical, segments I and II fused, segments 60–79. Setae regularly distributed around segmental equators, numbering 63–64 at VII, 46–56 at XX, 3 between male pores, setal formula AA:AB:ZZ:YZ = 1:1:2:1 at XIII. Female pore single at XIV, on 0.1–0.2 mm circular porophore. Prostomium epilobic with tongue open, purple-brown dorsally, unpigmented ventrally, setal rings lighter in color, clitellum not developed, formalin preservation. First dorsal pores at 12/13. Clitellum not developed.

Male pores superficial on small round porophores at lateral margins of ventrum in XVIII at 13 th setal line, 0.16–0.31 circumference apart ventrally; paired large oval equatorial genital papillae in XVIII between the male pores. Four pairs of spermathecal pores in 5/6–8/ 9 in 17 th setal line, at lateral margin of ventrum within white areas, 0.22–0.47 circumference apart.

Septa 5/6–8/9 thin, 9/10 absent, 10/11 thin, 11/12–13/14 very thin.Gizzard globular in VIII. Intestine beginning in XV, lymph glands not found. Typhlosole vestigial from XXVII. Intestinal caeca originating in XXVII and extending anteriorly to about XXV, manicate with 7–8 lobes decreasing in volume from ventral to dorsal, lobes otherwise smooth, uniform, minor caecal development as multi-lobed shallow pockets in XXVIII and XXIX; characteristic white villous lining present inside these additional caeca. Hearts within X–XIII, esophageal. Male sexual system holandric, testes and funnels in ventral paired sacs in X and XI. Seminal vesicles paired in XI and XII, no dorsal lobes. Prostates in XVIII, extending from XVII–XVIII; both glandular portions consist of two main lobes, each main lobe divided into two to three leaflets.

Ovaries in XIII. Four pairs of spermathecae in VI–IX; ampulla a very small pouch, flattened chili-shaped, stout duct shorter than ampulla; diverticulum very small and transparent, with stalk shorter than ampulla, no nephridia on spermathecal ducts.

Remarks. Amynthas ammalinei sp. nov. is closest to A. manicatus manicatus ( Gates, 1931) and A. manicatus decorosus ( Gates, 1932) , both of which have manicate caeca in XXVII and additional smaller manicate caeca in some or all of XXVIII–XXX. Amynthas m. manicatus has large longitudinally oriented oval genital papillae medial to the male porophores, longer spermathecal diverticula and a larger body size. Amynthas m. decorosus is quite variable in the male porophores including in materials from several locations in Myanmar and northern Thailand, but none of the listed variants match Amynthas ammalinei sp. nov.

For completeness of comparisons with other A. corticis -group species, we now consider the following Laotian earthworm species names: A. duplidiverticulatus ( Thai et Samphon, 1988) , A. lunatoides ( Thai et Samphon, 1988) , A. munghumensis ( Thai et Samphon, 1988) , A. samphoni ( Thai et Samphon, 1988) , A. alluxoides ( Thai et Samphon, 1988) , A. neoexilis ( Thai et Samphon, 1988) , A. edita honguanus ( Thai et Samphon, 1988) , A. seponensis ( Thai et Samphon, 1989) , and A. abdita khaokoaiana ( Thai et Samphon, 1989) . Except for A. munghumensis and A. seponensis , the other Laotian species mentioned have various genital papillae in the male pore regions, but Amynthas ammalinei sp. nov. has paired oval papillae in XVIII, distinguishing it from these two species. A. munghumensis and A. seponensis also differ by having invaginate male porophores, whereas Amynthas ammalinei sp. nov. has male pores superficial on small round porophores.

Amynthas ammalinei sp. nov. is similar to A. alluxoides with respect to the shape of the male field, but it differs in the shape of the diverticulum and body length. Amynthas ammalinei sp. nov. has very small diverticula, with the stalk shorter than the ampulla, but A. alluxoides has diverticula longer than the ampulla, and the new species is shorter than A. alluxoides (40–44 mm vs. 100 mm). These details are given mainly because the data on Thai and Samphon’s species are incomplete. Amynthas ammalinei sp. nov. can be distinguished from other A. corticis -group species by large paired oval equatorial genital papillae in XVIII between the male pores in combination with three pairs of manicate intestinal caeca and the presence of septum 8/9. The oval equatorial genital papillae shape is peculiar to this species.

Figures

FIGURE 2. Amynthas ammalinei sp. nov. (A, B). A: ventral view; B: intestinal caeca; C: spermatheca. Scale bars 2 mm.