Metaphire bahli ( Gates, 1945 )

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 : 126-127

Metaphire bahli ( Gates, 1945)

( Figures 7–8 , Table 3 )

Pheretima peguana – Kirtisinghe 1939: 89.

Pheretima bahli Gates 1945 , Spol. Zeyl., 24: 85 – Gates 1972: 209; Thai 1983: 124; Thai 1987: 6, 2000: 308; Thai & Samphon 1989: 62, 1991: 4; Thai & Do 1989: 77, Thai et al. 2004: 758; Nguyen 1994: 39; Pham 1995: 68, 2010: 62; Nakamura 1999: 40; Huynh 2005 2005: 87; Nguyen & Tran 2008: 184; Nguyen et al. 2010: 114, 2011: 1025, 2012: 146; Nguyen & Nguyen 2010: 123; Nguyen & Huynh 2011: 1018; Nguyen 2013: 46, 2014: 109.

Metaphire bahli – Sims & Easton 1972: 239; Easton 1982: 730; Blakemore 2006, 2008: 22; 2016: 29; Nguyen et al. 2016: 51 , 2017b: 98 , 2017a: 894 , 2020: 3 , 2021a: 14, 2021b: 1, 2021c: 105; Bantaowong et al. 2016: 63; Narayanan et al. 2019: 100; Lam et al. 2021: 17699.

Pheretima saigonensis Omodeo, 1956: 327 .

Type locality. Sri Lanka (Colombo) ( Gates, 1945)

Type material. unknown.

Diagnosis: Body cylindrical, length 87–139 mm, diameter 3.5–4.9 mm, segments 83–127. Prostomium epilobous. First dorsal pore at 12/13. Three pairs of spermathecal pores in ventral intersegments 6/7/8/9, bithecate. Male pores located inside copulatory pouches in xviii. Two pairs of slit-shaped genital markings in intersegments 17/18 and 18/19, in line with the openings of copulatory pouches. 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 species was usually found in leaf litters or in soil surface (depth of 0–5 cm).

Distribution. India ( Narayanan et al. 2019), Sri Lanka ( Gates 1945), Laos, Cambodia ( Thai & Do 1989), Myanmar ( Gates 1972), Thailand ( Bantaowong et al. 2016), Australia ( Easton 1982), Bangladesh, Japan, Philippines, Indonesia ( Michaelsen 1922; Blakemore 2006), and very commonly found in Vietnam ( Nguyen et al. 2016, 2021a, 2021c; Lam et al. 2021) ( Fig. 3 ).

Remarks. Gates (1945) originally did not mention the ventral distance between spermathecal pores and a concave male region in M. bahli , but in 1972 he stated that specimens with a concave male region was a typical form for all records in Myanmar, Philippines, and Sri Lanka (known as Ceylon). Gates (1972) also reported the ventral gap between spermathecal pores of less 0.5 body circumference whereas Easton (1982) measured that gap of about 0.25 body circumference ( Gates 1945, 1972; Easton 1982). The typical form was also recorded in India ( Narayanan et al. 2019).

In Vietnam, Metaphire bahli was found with two morphological forms. The first one is the typical form with a concave male region, and was found commonly in other places ( Myanmar, Philippines, Sri Lanka, India, Thailand …) ( Fig. 7 ). The other form was recorded only in islands (Hon Tre and Lai Son) that characterized by a non-concave male region, and a wider ventral distance between spermathecal pores (0.25–0.29 vs. 0.15–0.25 body circumference apart) ( Fig. 8 ). Gates (1945, 1972, 1975) also reported the lack of the septum 10/11, however, in our specimens, this septum is present ventrally to separate anterior testis sacs and their seminal vesicles. In addition, the genetic divergence between two morphological forms ( M. bahli (I) and M. bahli (II)) was only 9.0%±1.2%. This low divergence suggested two morphological forms be a same species.

The K2P intraspecific genetic distance of M. bahli was 1.0%±0.2%. The genetic distance between M. bahli and other Metaphire species was from 12.9%±1.5% (with M. peguana laisonensis ) to 20.9%±2.0% (with M. grandiverticulata ) ( Table 4 ).

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 8. Metaphire bahli (Gates, 1945) not concaved male region. A. Ventral view of the male pore region, B. Left prostatic gland, C. Ventral view of spermathecal region, D. Right spermathecae, E. Caecum, F. Transverse body section of accessory gland. Scale bar=1 mm.

FIGURE7. Metaphire bahli(Gates, 1945) concavedmale region.A.Ventral view of the male poreregion,B. Left spermathecae, C. Left prostatic gland, D. Caecum, E. Ventral view of spermathecal region, F. Transverse body section of the male copulatory pouch, G. Transverse body section of accessory gland. Scale bar=1 mm.