Table 4.

Morphological diagnostic keys to each species of the five TTCMs.

1. The original species with one shell, the outer surface of shell with three spiral whorls.

2. The outer surface usually with attachments.

3. The outer brown or turquoise, usually with attachments such as bryozoans…………………………………………………..….H. discus.

3. The outer usually brick-red, with attachments similar to white lime………………………..……………………………….....…H. ruber.

2. The outer surface without attachments.

4. The outer not smooth.

5. The outer dark red or brown, with yellowish-brown cloudiness………………………………………………………H. diversicolor.

5. The outer ecru……………………………………………………………………………………………………………....H. laevigata.

4. The outer smooth………………………………………………………………………………………………………………..H. asinina.

1. The original species with one right and one left shells, without spiral whorls.

6. The outer surface with distinct radiated ribs.

7. The inner surface of shell with a row of hinge denticles.

8. The outer with brownish coat and minute hairs

9. The shell small………………………………………………………………………………………………………….A. subcrenata.

9. The shell large…………………………………………………………………………………………………………….....A. inflata.

8. The outer without minute hairs……………………………………………………………………………………………….A. granosa.

7. The inner surface of shell without hinge teeth

10. Trace of adductor unobvious………………………………………………………………………………….…O. talienwhanensis.

10. Trace of adductor mostly in half-moon-shape…………………………………………………………………......…….O. rivularis.

6. The outer surface without distinct radiated ribs.

11. The right shell with one or two lateral teeth.

12. The right shell with one lateral tooth………………………………………………………………………………..….. H. cumingii.

12. The right shell with two lateral teeth.

13. The left shell with one lateral tooth………………………………………………………………………..………… M. meretrix.

13. The left shell with two lateral teeth……………………………………………………………………………………. C. plicata.

11. The right shell without lateral teeth.

14. The outer with concentric growth ring pulses……………………………………………………………………………… C. sinensis.

14. The outer with fine concentric growth lines, forming slices……………………………………………………………. P. martensii.