Amynthas tertiadamae ( Michaelsen, 1934 )

Amynthas tertiadamae ( Michaelsen, 1934)

( Figure 6 View Figure 6 )

Pheretima tertiadamae Michaelsen, 1934: 535 View in CoL , figs XXIII–XXV.

Amynthas tertiadamae – Sims & Easton 1972: 235, 246.

Material examined

40 matures (CTU-EW 095.01) An Son Island ( 09°41 ʹ 11.1 ʹʹ N, 104°21 ʹ 10.8 ʹʹ E), Kien Hai District , Kien Giang Province, 17 November 2013, coll GoogleMaps . Kim-Binh T. Trinh ; 39 matures (CTU-EW 095.02) same locality, but 13 October 2014 GoogleMaps .

Diagnosis

Small size, length 68–92 mm, diameter 2.2–3.0 mm, 87–122 segments. Prostomium 1/2 epilobous. First dorsal pore in 12/13. Setal number 32–47 in viii, 43–53 in xxx, 6–10 between male porophores in xviii; setal distance aa> ab, zz> zy. Four pairs of spermathecal pores in lateroventral intersegments 5/6/7/8/9. Male pores located in xviii, without copulatory pouches. Genital marking absent in the spermathecal region, but two pairs in 17/18 and 18/ 19 in front of and behind the male pores, respectively. Testis sacs separated. Holandric. Intestinal caeca simple, xxvii–xxiv. Septa 8/9/10 absent.

Re-description

External characters. Body cylindrical, small size; length 68–92 mm, diameter 2.2– 3.0 mm, weight 0.29–0.54 g; 87–122 segments. Dorsum darkish brown, but ventrum paler.

Prostomium 1/2 epilobous (open) First dorsal pore in 12/13. Setae perichaetine, short; pre-clitellar setae stouter and sparser than post-clitellar setae, 32–47 in viii, 43–53 in xxx, 6–10 between male porophores in xviii; setal distance aa> ab, zz> zy. Clitellum annular, xiv–xvi, greyish brown, smooth and without setae and dorsal pores. Female pore single, mid-ventral in xiv.

Spermathecal pores four pairs, in lateroventral intersegments 5/6/7/8/9. Genital markings absent in the spermathecal region.

Male pores directly opened in xviii, without copulatory pouches; ventral distance between male porophores about 0.4× body circumference. Porophores slightly elevated from body wall. Two pairs of small, bean-shaped genital markings in front of and behind porophores in xviii.

Internal characters. Septa 5/6/7/8 thickened, 8/9/10 absent, 10/11/12/13 thin. Oesophageal gizzard after viii. Intestinal origin at xv; caeca simple, within xxvii–xxiv, enlarged basally. Last hearts in xiii. Pharyngeal micronephridia poorly developed in 5/6/ 7. Lymph glands from 16/17, small, lobuled. Typhlosole simple, lamelliform (segments 24–41).

Spemathecae paired in vi–ix. Spermathecal ampulla large, egg-shaped, whitish yellow; duct stout, about one-quarter ampulla length. Diverticula directly attached to base of ampulla duct, strongly coiled and folded, shorter than ampulla; distal part enlarged to be a seminal chamber. No accessory glands.

Holandric. Testis sacs separated in x, xi. Seminal vesicles well developed within xi–xii. Ovaries invisible; oviduct after septum 12/13. Prostate glands deeply lobuled, paired in xvi–xxi; prostatic ducts U-shaped, slightly bigger distally. Accessory glands invisible.

Habitats

All specimens were found in clay soils in natural forest and plantation.

Remarks

New material was collected in An Son Island , about 60 km southeastward from the type locality, Phu Quoc Island . New material totally agrees with Michaelsen (1934) ’s description.

The species is fairly close to Amynthas juliani ( Perrier 1875) by having first dorsal pore in 12/13, four pairs of spermathecal pores in intersegments 5/6/7/8/9, no copulatory pouches, simple intestinal caeca, deeply lobuled prostatic glands and genital markings in male region. However, A. juliani has larger size ( 260–389 mm in length) and more segments (126–260 segments), prolobous prostomium, three pairs of genital markings on setal rings of xvii, xix and xx, thickened septa 8/9, mushroom-shaped spermathecal ampulla, and diverticula being not coiled ( Perrier 1875).