A notable peculiarity of the subfamily Alminae is a tendency to extensions of the body wall in the vicinity of or including the male pores. These extensions may be mere protuberances, as in some Drilocrius species; or involve a greater extent of the body wall, as in Glyphidrilocrius, or take the form of wing or keel-like structures (alae) in Glyphidrilus

• or paddle-shaped claspers in Drilocrius alfari

• and as claspers in all species of Alma. In Drilocrius alfari, the male pores lie near the bases of the claspers but in Alma they are near the tips of the claspers which are furnished with genital chaetae and sucker-like structures.

• The male pores are one pair, on segments 15-30, always inconspicuous, intraclitellar or preclitellar. Female pores are on segment 14 but Glyphidrilus kukenthali is one of only three ‘earthworm’ species known to have two pairs of female pores, in 13 and 14. Spermathecal pores are behind the testes (as in microchaetids), but are rarely continued into and anterior to the testis segments; they are sometimes (some Alma species) translocated into the hindbody; and are usually (with the spermathecae) multiple in an intersegment. Testes are paired in segments 10 and 11 or (Areco) 11 only. Prostate-like glands are rarely present.

The subfamily Criodrilinae contain a single genus, Criodrilus. In Criodrilus lacuum the male porophores are very strongly protuberant, filling segments 15 and 16 longitudinally. Spermathecae are absent (a rare condition in oligochaetes) and one to several spermatophores containing the sperm are received from the partner; these are curved, horn-shaped, hard but flexible structures approximately 1 mm long and maximally about 0.4 mm wide, at the expanded base; attached in the vicinity of the genital field.