Uktena, Fend, Steven V., Rodriguez, Pilar & Lenat, David R., 2015

Fend, Steven V., Rodriguez, Pilar & Lenat, David R., 2015, Uktena riparia n. gen., n. sp. (Annelida, Clitellata, Lumbriculidae), a new spermatophore-producing oligochaete, Zootaxa 3994 (3), pp. 411-424 : 412-413

Uktena n. gen.

Included species: Uktena riparia n. sp. (type species by monotypy)

Diagnosis (autapomorphies are underlined). Medium-sized to large worms with long, superficially-ringed proboscis. Chaetae simple-pointed. Reproductively-mature worms have several modified chaetae in ventral chaetal bundles of two postatrial segments. Two pairs of lateral blood vessels in posterior segments, with many blind branches. Nephridia begin on 10/11. One pair of testes in VIII, one pair of ovaries in IX. Male pores paired on VIII, in deep copulatory bursae with associated glands. Prosoporous atria elongate-cylindrical, ampulla covered with clusters of prostatic cells; ectal ducts produce tubular spermatophores. One pair of sperm funnels, extending back one or more segments in sperm sac. Vasa deferentia do not penetrate posterior septum (8/9). Female pores on posterior septum of first post-atrial segment. Spermathecae paired in atrial segment, anterior to atria; spermathecal pores within deep bursae containing a glandular, protrusible, copulatory organ for spermatophore attachment.

Remarks. Uktena n. gen. has three distinctive autapomorphies, all of which were previously unknown in the family Lumbriculidae : a unique arrangement of genital chaetae, a “copulatory organ” within a large, muscular spermathecal bursa, and tubular spermatophores (see Discussion). The presence of spermathecae in the atrial segment is unusual within the family, but this character is shared with at least three other lumbriculid genera, as well as two species of Dorydrilus Piguet, 1913 (see Discussion). The combination of a prosoporous atrium and spermathecae in the male segment suggests that Uktena is closely related to Kincaidiana Altman, 1936 , also a large worm with a filiform proboscis. However, Kincaidiana has the male pores in IX (instead of VIII) and has spermathecae also in postatrial segments. Guestphalinus Michaelsen, 1933 and Cookidrilus Rodriguez & Giani, 1987 are differentiated from Uktena and Kincaidiana by their semiprosoporous male ducts, as well as by the position of atria in IX and X, respectively. The three Cookidrilus species are small worms, without a proboscis, and with spermathecae also in post-atrial segments ( Rodriguez & Giani 1987, Route et al. 2004, Rodriguez et al. 2014).