Patinapta, Heding, 1928

Key to Japanese species of Patinapta View in CoL (with present four new species).

1. In tentacles, rod-shaped ossicles present................................................................... 2

- In tentacles, ossicles mostly elongated granules present....................................... P. edentatus sp. nov.

2. In mid-body wall, more or less symmetrical anchor plate ossicles present......................................... 3

- Anchor plate ossicles possess strongly distorted layout of few large perforations and small marginal perforations, with small numbers of teethed perforations. Anchor ossicles with semicircular T-shaped basal end............... P. deformis sp. nov.

3. Anchor plate ossicles in mid-body wall mostly larger than 100 μm.............................................. 4

- Anchor plate ossicles with few numbers of teethed perforations and few numbers of teeth on peripheral plate edge, basal tip of plate depressed, resulting in double tips................................................. P. parvaspiculus sp. nov.

4. Anchor plate ossicles approximately 90–110 μm in length, without minute teeth on peripheral plate edge. Anchor ossicles possess teeth (barb).................................................................................... 5

- Anchor ossicles mostly lacking teeth (barbless) in both immature and mature animals................ P. neglectus sp. nov.

5. Most of perforations of anchor plate ossicles with teeth, which are sharp and closely and continuously standing.... P. ooplax View in CoL

- small numbers of perforations (1–4) of anchor plates with teeth, teeth blunt and discontinuously standing.... P. taiwaniensis View in CoL