Tanycypris siamensis Savatenalinton & Martens, 2009a

(Figs 5C, 6C, 6H, 7E, 10)

partim 1972 Strandesia camaguinensis (Tressler) —Okubo: 10, fig. 1 a–c.

Diagnosis. L = 1.02–1.15 mm, H = 0.45–0.52 mm; carapace in dorsal view narrow, in lateral view elongated with subequally rounded anterior and posterior margin. Surface of valves relatively smooth with a brown-yellowish colour. A1 with big Wouters organ (Fig. 10A,B), but without a dorsal subapical seta on the first segment. Long Rome organ present (Figs 5C, 10A). T1 with two a-setae, one b-seta and one d-seta, masticatory process with 14 setae (Fig. 6H). T2 with d1 longer than d2. CR stout with a hirsute Sp (Fig. 6C). CR-attachment very stout with a strong, curved db and a thick and short vb (Fig.7E). Males have been reported (Savatenalinton 2011), but so far no description has been published.

Similar species. Owing to the carapace shape, T. siamensis cannot be mistaken for T. madagascarensis . For similarities with T. alfonsi n. sp., T. centa and T. pellucida see descriptions of these species.

Remarks. Savatenalinton & Martens (2009a) described Tanycypris siamensis from Thailand and deposited the holotype (No. 3099) and one paratype (No. 3100) in the ostracod collection of the Royal Belgian Institute of Natural Sciences. Two paratypes (MSU-ZOC 018—019) are deposited in the Natural History Museum Mahasarakham in Thailand. While the type material has not been studied, five specimens provided by the authors of the species have been investigated in the frame of the present study.

According to Savatenalinton & Martens (2009a) T. siamensis has no or an inconsiderable Wouters organ. However, the material investigated in the frame of this study showed a clearly visible Wouters organ (one fourth of the length of segment 1 + 2) (Fig. 10A,B).