Amynthas antoanensis Nguyen, Lam & Nguyen, 2022

Grzelak, Katarzyna & Sørensen, Martin V., 2022, Echinoderes blazeji Grzelak & amp; Sørensen 2022, sp. nov., Zoological Studies 55 (52), pp. 1-13 : 8-10

Amynthas antoanensis Nguyen, Lam & Nguyen

sp. nov. lsid:zoobank.org:act: 56BBD3F7-9F6C-4E3A-AC59- 2A21E3B72ABE ( Fig. 5 , Table 1)

Material examined: Holotyp: One mature ( CTU-EW 038-h01) forest, An Toan commune, Binh Dinh province, 29/12/2006, coll. Pham Hoai Vu.

Diagnosis: Large-size worm, length ca. 685 mm, diameter ca. 19 mm. First dorsal pore in 12/13. Prostomium epilobous. Spermathecal pores round and small, ventrally paired in intersegmental furrows 5/6/7/8/9. Male pores located in xviii, without copulatory pouches. Genital makings present on both spermathecal and male pore regions (on viii, ix, and xviii). Holandric. Spermathecal ampulla oval-shaped, duct short; diverticula coiled. Testis sacs separated. Intestinal caeca simple. Septa 8/9/10 absent.

Etymology: Named after the type locality, An Toan commune.

Description: External characters: Body cylindrial, length 685 mm, diameter 19 mm (20 mm / viii, 21 mm /xvi, 18 mm /xviii, 17 mm /xxx), weight 97.66 g, 335 segments,. Dorsa blackish grey, but ventra paler. Prostomium 1/3 epilobous. First dorsal pore large, in 12/13. Setae perichaetine, short; pre-clitellar setae stouter and sparser than post-clitellar setae, 126 in v, 137 in viii, 149 in x, 177 in xx, 228 in xxv, 249 in xxx, 55 between male porophores in xviii; setal distance aa = 2.0ab, zz = 1.0-2.0zy. Clitellum annular, xiv-1/2xvii, blackish brown, smooth and without setae and dorsal pores. Female pore single, mid-ventral in xiv. Spermathecal pores very small, ventrally paired in intersegmental furrows 5/6/7/8/9, hardly visible externally. Genital markings ventrally paired present on viii and ix: three pairs behind setal rings on viii, and two pairs in front of setal ring on ix. Male pores directly opened in xviii, without copulatory pouches; ventral distance between male porophores about 0.35x body circumference. Two pairs of genital markings present between male porophores, behind setal ring of xviii; the anterior pair slightly more medial to male pores compared to posterior pair.

Internal characters: Septa 4/5/6/7/8 very thickened, 8/9/10 absent, 10/11/12/13 thin. Oesophageal gizzard within viii-x. Intestinal origin at xv; caeca simple, originating at xxvii and extending anteriorly to xxiv. Last hearts in xiii. Pharyngeal micronephridia developed in 5/6/7. Lymph glands present from 31/32. Typhlosole simple, lamelliform, poorly developed. Spemathecae paired ventrally in vi- ix. Spermathecal ampulla oval-shaped; duct extremely short, not distinct from ampulla. Diverticula very short, opalescent, coiled, directly attached to base of ampulla. Accessory glands present in viii and ix. Holandric. Testis sacs separated, in x and xi. Seminal vesicles poorly developed within xi-xii. Oviduct poorly developed on septum 12/13 posteriorly; ovaries developed in 13/14. Prostate glands racemose, paired within xviii; prostatic ducts strong, slightly bigger distally. Two pairs of accessory glands present.

Habitat: The species was found in the rich forest of An Toan commune. It can be epigeic

(A)

species because it was collected from soil surface.

Remarks: The new species can be classified into the diffringens species group characterised by holandric and four pairs of spermathecal pores in intersegments 5/6/7/8/9 ( Sims and Easton 1972). However, it can be distinguished by its large size and pattern of genital markings in spermathecal and male regions.

The new species is fairly similar to the other large Amynthas earthworms from Vietnam, Amynthas dangi ( Thai, 1984) and Amynthas munglonganus ( Thai & Tran, 1986) , by the very large size, holandric, prostomium epilobous, septa 8/9/10 absent, last hearts in xiii, and copulatory pouches absent ( Table 1). However, Amynthas dangi differs from the new species in having two pairs of spermathecal pores in 7/8/9, a genital marking close to the male pore and an additional three pairs of genital markings on ventral xviii and xix. Amynthas munglonganus is distinguished from the new species by the first dorsal pore in 12/13, three pairs of small genital markings located closely to the spermathecal pores in 5/6/7/8, a medium genital marking next to the male pore, and different shape of spermathecal ampulla.

The new species is also fairly similar to the other large Metaphire species, M. taiwanensis Tsai, Tsai & Shen, 2004 , by having four pairs of spermathecal pores in 5/6/7/8/9, septa 8/9/10 absent, intestine originating from xv, and caeca simple. However, M. taiwanensis differs from the new species in the first dorsal pore in 12/13 or 13/14; genital markings absent in the spermathecal region, but oval-shaped, located anteriorly next to porophores; male pores located inside copulatory pouches.

Figures

Fig. 5. Amynthas antoanensis sp. nov., holotype. A, G: Male pore region, ventral view (mp = male pore; gm = gential markings); B, I: Spermathecal region (sp = spermathecal pore; gm = gential markings); C, D: Spermathecae (amp = ampulla; dv = diverticula); E, H: Intestinal caeca; F: Prostatic gland. Scale bar = 1 mm.