Four new earthworms of the Amynthas aeruginosus species group (Oligochaeta: Megascolecidae) from Nam Xam NBCA, Laos

Earthworm specimens collected from the Nam Xam National Biodiversity Conservation Area, Laos belong to four new species of megascolecid earthworms: Amynthas banlaoensis sp. nov., Amynthas khamlai sp. nov., Amynthas phadeangensis sp. nov., and Amynthas naphopensis sp. nov. All four new species key to the aeruginosas group in Sims & Easton (1972), defined by having spermathecal pores in 7/8/9 and simple intestinal caeca. Amynthas banlaoensis sp. nov. has male pores superficial near lateral margins of XVIII in the 12^th setal lines, on short columnar 0.3-0.5 mm diameter porophore, and tubercular genital markings paired in VII or VIII. Amynthas khamlai sp. nov. has male pores on retractable, eversible round porophores near the lateral margins of the ventrum in XVIII, and circular genital markings in paired postsetal linear groups of two or three on trailing edges of VII and VIII. Amynthas phadeangensis sp. nov. has male pores on alate porophore swellings composed of concentric rings, with paired genital papillae medial to the male porophores and embedded in the concentric rings. It has paired postsetal genital markings in 8 ^th - 9^th setal lines of VIII and IX. Amynthas naphopensis sp. nov. has male pores in small invaginations partly covered by raised U-shaped flap concave medially, and lacks other genital markings.