Pithemera tao sp. nov.

(Fig. 3)

Material examined. Holotype: 1 adult, NCHUZOOL 13541, 22°02’1.6”N, 121°33’57.7”E, Yeyin, Lanyu, Taitung Co., Taiwan, coll. Yu-Hsi Wang et al., 7 Jan. 2008. Paratypes: 5 adults, NCHUZOOL 13542, same collection data as for holotype.

Description. External: Small. Dimensions 27–43 mm by 1.9–2.2 mm in x, 1.9–2.6 mm in xxx, 2.1–2.5 mm in clitellum; body cylindrical throughout, segments 55–90; 5–7 setae between male pores. Setal formula AA: AB: YY: YZ = 1.5: 1: 3: 1.75 on xxv. Prostomium, epilobic. Female pores paired on xiv. First dorsal pore at 12/13. Clitellum annular xiv–xvi 1/2; setae on xiv and xv (Fig. 3 a).

Male pores on xviii, without genital marking (Fig. 3 a). Spermathecal pore single, middle at 4/5–6/7 (Fig. 3 a).

Internal: Septa, 4/5–7/8 thin, 8/9–9/10 absent, 10/11–13/14 thick, gizzard in viii–x or ix–x. Intestinal origin from xiv, typhlosole simple 1/4 lumen diameter from xxi. Intestinal caeca simple and short, originating in xxi, extending anteriorly to xix (Fig. 3 d). Without oesophageal heart.

Male sexual system holandric, testes in x and xi; seminal vesicles in xi and xii. Prostates small in xviii, round-shaped extending xvii to xix (Fig. 3 c). Spermatheca single in v–vii; ampulla ovoid, adiverticulate or diverticulate (Fig. 3 b).

Etymology. This species is named after the aboriginal tribe, the Tao Tribe (= Yami Tribe), who dwell on the island of Lanyu. The name is used as a noun in apposition.

Remarks. Pithemera tao sp. nov. is similar to P. bicincta (Perrier, 1875), P. palaoensis (Ohfuchi, 1941), P. philippinensis James, Hong & Kim, 2004, P. sedgwicki sedgwicki (Benham, 1897), and P. sempoensis (Kobayashi, 1938), but can be distinguished by the spermathecal pore and spermatheca. P. bicincta, and P. philippinensis have 5 pairs of spermathecal pores at 4/5–8/9. Pithemera sedgwicki sedgwicki and P. sempoensis have 3 pairs of spermathecal pores at 5/6–7/8. Pithemera palaoensis has 3 pairs of spermathecal pores at 4/5–6/7. All of the above species have paired spermathecal pores and spermathecae with diverticula. Pithemera tao has only a single spermathecal pore at 4/5–6/7.