Metaphire nhuongi Nguyen, 2016

Nguyen, Tung T., Lam, Dang H. & Nguyen, Anh D., 2023, A revision of the Metaphire peguana species-group (Oligochaeta: Megascolecidae) from Vietnam, Zootaxa 5255 (1), pp. 113-135 : 131-132

Metaphire nhuongi Nguyen, 2016

( Figure 13 , Table 3 )

Metaphire nhuongi Nguyen 2016: 442 , fig. 2; Nguyen et al. 2021c: 105.

Pheretima sp. 10 – Nguyen et al. 2012: 146.

Pheretima sp. 14 – Nguyen 2013: 85, 2014: 112.

Type locality. Vietnam (An Giang: Co To mountain ) ( Nguyen 2016)

Type material. Laboratory of Zoology , Department of Biology, Can Tho University (EW.024.h01, EW.024. p02, EW.024.p03), Vietnam .

Diagnosis. Body cylindrical, large-medium size, length 213–339 mm, diameter 8.9–9.5 mm, segments 120–148. Prostomium epilobous. First dorsal pore at 12/13. Four pairs of spermathecal pores in ventrolateral intersegments 5/6/7/8/9, bithecate. Two pairs of ellipsoid genital markings in intersegments 17/18 and 18/19, each with a small opening at the center. 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 found in the depth of 15–20 cm in soils of natural forests or in perennial mango gardens in a mountain foot. They excreted their feces to create columns emerging from the soil surface ( Nguyen 2016).

Distribution. Only recorded in Vietnam (An Giang: Co To, Phu Cuong, and Ta Pa mountains) ( Fig. 3 ).

Remarks. There were no significant morphological differences between individual found.

The K2P intraspecific genetic distance was 1.3%±0.3%. The genetic distance between M. nhuongi and other Metaphire species was from 17.6%±1.8% (with M. dorsomultitheca ) to 22.9%±2.1% (with M. grandiverticulata ) ( Table 4 ).

Key to species of Metaphire peguana species-group

1. – Bithecate, one pair of spermathecae per segment.......................................................... 2 – Polythecate, numerous spermathecae per segment......................................................... 6

2. – Four pairs of spermathecal pores in 5/6/7/8/9...................................................... M. nhuongi – Three pairs of spermathecal pores in 6/7/8/9............................................................... 3

3. – Genital markings paired in vi–ix............................................................. M. doiphamon – Genital markings absent in the spermathecal region......................................................... 4

4. – Spermathecal pores located ventrally. Ventral distance between spermathecal pores 0.15–0.29 body circumference. M. bahli – Spermathecal located more laterally. Ventral distance between spermathecal pores 0.33–0.50 body circumference....... 5

5. – The openings of genital markings small, slit-shaped or ellipsoid-shaped, in post-setal and pre-setal positions in xvii and xix, respectively....................................................................... M. peguana laisonensis – The openings of genital markings disc-shaped, in 17/18 and 18/19, expanding to reach two setal rings. M. peguana peguana

6. – Spermathecal pores located in ventral intersegments 6/7/8/9. Genital markings paired in 17/18 and 18/ 19 M. kiengiangensis – Spermathecal pores located in dorsal intersegments 7/8/9. Genital markings opening on the walls of the copulatory pouches M. dorsomultitheca

Figures

FIGURE 3. Distribution of Metaphire peguana species-group recorded all over the word (A) and in the South of Vietnam (B). 1. Metaphire bahli, 2. M. doiphamon, 3. M. dorsomultitheca, 4. Metaphire kiengiangensis, 5. Metaphire nhuongi, 6. Metaphire peguana laisonensis, 7. M. peguana peguana.

FIGURE 13. Metaphire nhuongi Nguyen, 2016. A. Ventral view of the male pore region, B. Ventral view of spermathecal region, C. Left spermathecae, D. Left prostatic gland, E. Caecum, F. Transverse body section of the male copulatory pouch, G. Transverse body section of accessory gland. Scale bar=1 mm.