Metaphire peguana laisonensis Nguyen & Nguyen, 2017

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 : 123-125

Metaphire peguana laisonensis Nguyen & Nguyen, 2017

( Figures 5–6 , Table 3 )

Metaphire peguana laisonensis Nguyen et al. 2017b: 900 , fig. 12; Nguyen et al. 2021c: 105.

Pheretima sp. 11 – Nguyen 2013: 78, 2014: 111.

Type locality. Viet Nam (Kien Giang: Lai Son island ) ( Nguyen et al. 2017b)

Type material. Laboratory of Zoology , Department of Biology, Can Tho University (EW.087.01), Vietnam .

Diagnosis. Body cylindrical, length 62–114 mm, diameter 2.7–4.4 mm, segments 62–111. Prostomium epilobous. First dorsal pore at 12/13. Three pairs of spermathecal pores in lateral intersegments 6/7/8/9, bithecate. Two pairs of ellipsoid genital markings in xvii and xix, each genital marking with a small opening at the center. Male pores located inside copulatory pouches in xviii. Septum 10/11 only present ventrally. Intestinal caeca simple. Holandric, testis sacs separated. Accessory glands coelomic, strongly covered by muscular-walled bursae in 17/18 and 18/19.

Habitat. The subspecies were found numerously in leaf litters in natural forest ( Nguyen 2014; Nguyen et al. 2017b).

Distribution. Only known in Vietnam (Kien Giang: Lai Son island; An Giang: Cam mountain) ( Nguyen 2014; Nguyen et al. 2017b) ( Fig. 3 ).

Remarks. Nguyen et al. (2017b) described a new subspecies, M. peguana laisonensis found in Lai Son Island (Kien Giang Province, Vietnam) based on the location of genital markings, spermathecal pores, and the attachment of the spermathecal diverticulum ( Fig. 5 ) ( Nguyen et al. 2017b). Previously, Nguyen (2013) identified samples collected from the Cam Mountain (An Giang Province) as M. bahli ( Fig. 6 ), and observed that these samples have intermediate characters between M. bahli and M. peguana , for example, slit-shaped genital markings in xvii and xix, and the much laterally wider spermathecal pores ( Nguyen 2013). The re-examination confirmed that specimens were definitely M. peguana laisonensis . There was a minor difference in the ending of the spermathecal diverticulum between the type specimens from Lai Son Island and samples collected from the Cam Mountain (An Giang Province) (attached directly to the base of the ampulla duct vs. attached to the middle of the ampulla duct).

Genetic distance of M. peguana laisonensis in Cam Mountain and M. peguana peguana was 12.2%±1.4%, and that distance with other Metaphire species was 12.9%±1.5% (with M. bahli (type I)) to 22.3%±2.1% (with M. grandiverticulata ) ( Table 4 ).

Notes: Intraspecific distances are in bold; na = no data

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 5, Metaphire peguana laisonensis Nguyen & Nguyen, 2017 in Lai Son island. A. Ventral view of the male pore region, B. Left spermathecae, C. Right prostatic gland, D. Lateral view of spermathecal region, E. Caecum, F. Transverse body section of the male copulatory pouch, G. Transverse body section of accessory gland. Scale bar=1 mm.

FIGURE 6. Metaphire peguana laisonensis Nguyen & Nguyen, 2017 in Cam Mountain. A. Ventral view of the male pore region, B. Right prostatic gland, C. Right spermathecae, D. Lateral view of spermathecal region, E. Caecum, F. Transverse body section of accessory gland. Scale bar=1 mm.