Amynthas xayi 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 : 276-277

Amynthas xayi Hong and James sp. nov.

( Fig. 3 )

Material examined. Holotype: 1 clitellate ( BDNUL 0057 ): Laos, Houaphanh Province, Viengthong District, Nam Et-Phouleoi NPA, Thad Ang waterfall area , 792 m (20°15.446′N, 103°08.921′E), good forest condition, dark soil and thick litter layer, July 21, 2005, Phimphet, Xay, Ammaline, Phoang, and K. Inkhavilay colls . Paratypes: 2 clitellates ( BDNUL 0058 , 0059 ), same data as holotype . Non-types: 5 clitellates, same data as for holotype .

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

Diagnosis. Four pairs of spermathecal pores deep in 5/6–8/9 at 9 th setal line; male pores superficial in XVIII at centers of round porophores, 0.17–0.29 circumference apart; no genital markings or papillae; caeca pinnate; first dorsal pore in 5/6.

Description. Dimensions 76–90 mm by 3.0– 3.5 mm at segment X, 3.4–3.5 mm at segment XXX, 3.4–3.5 mm at clitellum; body cylindrical, segments 67–83. Setae distributed around segmental equators, numbering 30–34 at VII, 42–45 at XX, 12–16 between the male pores; setae of II–VIII enlarged, setal formula AA:AB:ZZ:YZ = 2:2:6:3 at XIII. Female pore single at XIV at 0.3–0.4 mm on oval. Prostomium epilobic with tongue open, purple-brown anterior dorsal pigmentation, lighter ventrally and posteriorly, clitellum coffee color, formalin preservation. First dorsal pores at 5/6. Clitellum annular XIV–XVI; setae invisible externally.

Male pores superficial in XVIII at 8 th setal line, 0.17–0.29 circumference apart ventrally, at centers of round porophores surrounded by 3–4 thick white oval outer rings, at lateral margins of ventrum. Four pairs of spermathecal pores deep in 5/6–8/9 at 9 th setal line, 0.24–0.36 circumference apart ventrally at lateral margin of ventrum. Genital markings and papillae absent.

Septa 5/6, 6/7 thick, 7/8 thin, 8/9/10 absent, 10/11–13/14 thin. Gizzard globular in VIII–X. Intestine beginning in XV, and lymph glands missing. Typhlosole vestigial from XXVII. Intestinal caeca originating in XXVII and extending anteriorly to about XXV, slightly asymmetric pinnate-shaped with 6–7 dorsal, 6–7 ventral lobes. Hearts esophageal in X–XIII; X small. Male sexual system holandric testes and funnels in ventral paired sacs in X and XI. Seminal vesicle two pairs in XI and XII, no dorsal lobes. Prostates in XVIII, 6 main lobes, extending between XVII and XXIII; stout short muscular duct very wide in center.

Ovaries in XIII. Four pairs of spermathecae in VI–IX; ampulla very large lanceolate pouches, irregularly folded or flattened, slender duct shorter than ampulla; diverticulum chamber egg-shaped, iridescent on short stalk attached to duct near body wall; no nephridia on ducts.

Remarks. The distinctions from the main body of the A. corticis -group are the pinnate caeca and the forward position of the dorsal pores. The Burmese andersoni -group of 9 octothecate species in Gates (1972) is entirely composed of species with simple caeca and first dorsal pores in 12/13 or nearby and has a range including northeastern Burma, northern Thailand, and China. Thus, it is likely that similar species are present in northern Laos, but none have been found as yet. Amynthas xayi sp. nov. is similar to Amynthas piyakarnae sp. nov. with respect to the pinnate intestinal caeca, but it can be separated easily by the following characters: the new species has a lack of genital markings and papillae, but Amynthas piyakarnae sp. nov. has genital markings on circular, paired pre-setal VIII and IX and genital papillae on XVIII and XIX with very short stalks or sessile. Amynthas xayi sp. nov. has ampulla very large lanceolate pouches, but Amynthas piyakarnae sp. nov. has ampulla oval, small black spots on surface. This new species also has fewer setae in post-clitellar segments, and smaller body size.

Figures

FIGURE 3. Amynthas xayi sp. nov. (A, B). A: ventral view; B: intestinal caeca; C: spermatheca. Scale bars 2 mm.