Amynthas exiguus exiguus ( Gates, 1930 )

Nguyen, Tung T., Trinh, Kim-Binh T., Nguyen, Hong-Lan T. & Nguyen, Anh D., 2017, Earthworms (Annelida: Oligochaeta) from islands of Kien Hai District, Kien Giang Province, Vietnam, with descriptions of two new species and one subspecies, Journal of Natural History 51 (15 - 16), pp. 883-915 : 888-890

Amynthas exiguus exiguus ( Gates, 1930)

( Figure 5 )

Pheretima exigua Gates, 1930: 310 ; Gates 1939: 89.

Pheretima exigua exigua – Gates 1972: 184.

Amynthas exiguus exiguus – Sims & Easton 1972: 235.

Material examined

31 matures (CTU-EW 094.01) Hon Tre Island (09°58 ʹ 13.0 ʹʹ N, 104°51 ʹ 15.5 ʹʹ E), Kien Hai District , Kien Giang Province, 13 November 2013, coll . Kim-Binh T. Trinh.

Diagnosis

Small size, length 40–69 mm, diameter 2.3–3.0 mm, 65–93 segments. Prostomium 1/2 epilobous. First dorsal pore in 12/13. Setal number 32–42 in viii, 40–47 in xxx, 8–15 between male porophores in xviii; setal distance aa = 2.0 ab, zz = 2.0 zy. Four pairs of spermathecal pores in 5/6/7/8/9. Male pores located in xviii, without copulatory pouches. Genital markings present, but variable in the spermathecal and male regions. Testis sacs separated. Holandric. Intestinal caeca simple, short, xxvii–xxv. Septa 8/9/10 absent.

Habitats

The species was found in clay soils on hill slopes, and sometime in soils inside rocky hollows. It was usually collected from fruit plantations.

Remarks

A total of 31 specimens were examined to show the variation in the number and position of genital markings in spermathecal and male regions. Genital markings are variable in front of setal rings in xvii, xviii, xix and xx, but the most common pattern is three pairs in xvii, xviii and xix (13 of 31 specimens). They are also variable from one to three pairs in front of setal rings in viii, ix and x.

Distribution

The species is widely known from Vietnam (Lao Cai, Son La, Ninh Binh, Gia Lai, Dak Lak, Kien Giang and An Giang) ( Nguyen et al. 2016). It is also known from Thailand and Myanmar ( Gates 1939, 1972).

Figures

Figure 5. Amynthas exiguus exiguus (Gates, 1930). (a, e) Male region (mp = male pore, gm = genital markings); (b, i) intestinal caecum; (c, g) spermathecae (amp = ampulla, dv = diverticulum); (d, f) prostatic gland (ag = accessory gland); (h) ventral view of spermathecal region (sp = spermathecal pore, gm: genital markings). Scale bar = 1 mm.