A revision of the Metaphire peguana species-group (Oligochaeta: Megascolecidae) from Vietnam Author Nguyen, Tung T. Department of Biology, School of Education, Can Tho University, Vietnam. Author Lam, Dang H. 0000-0002-1236-1087 Department of Biology, School of Education, Can Tho University, Vietnam. & lamhaidangct @ gmail. com; https: // orcid. org / 0000 - 0002 - 1236 - 1087 lamhaidangct@gmail.com Author Nguyen, Anh D. 0000-0001-9273-0040 Institute of Ecology and Biological Resources, Vietnam Academy of Science and Technology, 18, Hoangquocviet Rd., Caugiay, Hanoi. & ducanh 410 @ yahoo. com; https: // orcid. org / 0000 - 0001 - 9273 - 0040 & Graduate University of Science and Technology, Vietnam Academy of Science and Technology, 18, Hoangquocviet Rd., Caugiay, Hanoi. ducanh410@yahoo.com text Zootaxa 2023 2023-03-15 5255 1 113 135 http://dx.doi.org/10.11646/zootaxa.5255.1.15 journal article 10.11646/zootaxa.5255.1.15 1175-5326 7744555 3F27E81A-87C7-48CD-8DF7-6FFDA0CD4907 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. FIGURE 12. Metaphire kiengiangensis Nguyen & Trinh, 2015 . A. Ventral view of the male pore region, B. Transverse body section of the male copulatory pouch, C. Transverse body section of accessory gland, D. Left spermathecae, E. Right prostatic gland, F. Caecum. Scale bar=1 mm. 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 ).