Metaphire kiengiangensis Nguyen & Trinh, 2015

(Figure 12, Table 3)

Metaphire kiengiangensis Nguyen et al. 2015: 461, fig. 1; Nguyen et al. 2016: 60, 2017b: 898, 2021c: 105.

Pheretima sp.9 – Nguyen 2013: 75, 2014: 111.

Type locality. Vietnam (Kien Giang: Lai Son island) (Nguyen et al. 2015).

Type material. Laboratory of Zoology, Department of Biology, Can Tho University (EW.019.h01, EW.019. p02, EW.019.p03, EW.019.p04), Vietnam.

Diagnosis. Body cylindrical, large-medium size, length 176–280 mm, diameter 6.3–8.1 mm, segments 83–143. Prostomium epilobous. First dorsal pore at 12/13. Spermathecal pores numerous in ventrolateral intersegments 6/7/8/9, polythecate. Male pores located inside copulatory pouches in xviii. Two pairs of slit-shaped genital markings in 17/18 and 18/19. Male pores located inside copulatory pouches in xviii. Septum 10/11 present only ventrally. Intestinal caeca simple. Holandric, testis sacs separated. Accessory glands coelomic, strongly covered by muscularwalled bursae in 17/18 and 18/19.

Habitat. The species was extremely abundant in a leaf-litter layer under perennial mango gardens of mountainous areas; They excreted their feces to create columns emerging from the soil surface (Nguyen et al. 2015).

Distribution. Known only in Vietnam (Kien Giang: Hon Dat, Hon Me mountains, and Lai Son island) (Nguyen et al. 2015, 2017b) (Fig. 3).

Remarks. There is a minor difference in spermathecae between specimens collected from the mainland and from islands (ovoid-shaped spermathecae with thin duct vs. cylindrical-shaped with stout duct) (Nguyen et al. 2015).

The K2P intraspecific genetic distance was 0.7%±0.3%. The genetic distance between M. kiengiangensis and other Metaphire species was from 16.5%±1.8% (with M. bahli (II)) to 21.6%±2.0% (with M. grandiverticulata) (Table 4).