Kahayandrilus, Ohtaka & Wulandari, 2016

Ohtaka, Akifumi & Wulandari, Linda, 2016, Description of Kahayandrilus tundaiensis gen. et sp. nov. (Annelida: Clitellata: Tubificinae) from Central Kalimantan, Indonesia, Species Diversity 21 (1), pp. 43-47 : 43-44

Kahayandrilus gen. nov.

Type species. Kahayandrilus tundaiensis sp. nov., fixed by original designation.

Etymology. Named Kahayandrilus , referring to that the type species is a ‘worm’ (Greek drilus) from Kahayan River basin (masculine).

Diagnosis. Moderate sized tubificines with long and coiled vasa deferentia, ovoid atrial ampullae, and long ejaculatory ducts with uniform width. Penes soπ and thickwalled, devoid of penial sheaths, set in penial pouches. Chaetae sigmoid bifids, similar in dorsal and ventral bundles. No modified genital chaetae. No spermathecae.

Remarks. Kahayandrilus resembles Psammoryctides Hrabě, 1964 in having small, globular to ovoid atrial ampulla, long ejaculatory duct, and large penis set in a sac. However, Psammoryctides is defined by having wide and narrow parts in the ejaculatory ducts ( Hrabě 1964; Brinkhurst and Jamieson 1971; Loden 1978), while in Kahayandrilus the ejaculatory duct is uniform in width throughout the course. In addition, hair and pectinate chaetae, and spermathecal chaetae were usually present in most Psammoryctides species, while they are absent in Kahayandrilus . Psammoryctides species are distributed in western Palaearctic and Nearctic regions, far from the Oriental Southeast Asia.

Kahayandrilus resembles certain members in the genus Aulodrilus Bretscher, 1899 , for example, A. pigueti Kowalewski, 1914 and A. acutus Ohtaka and Usman, 1997 , in having ovoid atrial ampulla with solid prostate gland ( Ohtaka and Usman 1997). However, in Aulodrilus species ejaculatory duct is shorter than atrial length or virtually absent, being different from Kahayandrilus in which ejaculatory duct is more than three times longer than atrial length. Aulodrilus also differs from Kahayandrilus in having shorter and non-winding vas deferens and large number of chaetae with shorter upper teeth ( Brinkhurst and Jamieson 1971).

Isochaetides Hrabě, 1966 emended by Brinkhurst (1981) resembles Kahayandrilus in having only bifid chaetae and weakly developed cuticle on penis as well as long ejaculatory duct described in I. curvisetosus ( Brinkhurst and Cook, 1966) (q.v.). However, most members of Isochaetides have modified spermathecal chaetae and long tubular atria ( Hrabě 1966; Brinhurst 1981), both of which are absent in Kahayandrilus . Some species in Varichaetadrilus Brinkhurst and Kathman, 1983 , for example, V. fulleri Brinkhurst and Kathman, 1983 and V. psammophilus ( Loden, 1977) (q.v.), have only bifid chaetae as in Kahayandrilus . However, Varichaetadrilus spp. have elongate atrium and cuticular sheaths at the distal end of large erectile penes ( Brinkhurst and Kathman 1983), which are absent in Kahayandrilus .

Several genera in other naidid subfamilies ( Paranadrilus , Bothrioneurum , Jolydrilus , some Bacescuella (= Aktedrilus ) and some Ainudrilus ) lack spermathecae as in Kahayandrilus , but they have very different male ducts and other characters.