1. Rostrum truncated, slightly wavy; body size: 337–365 × 194 – 171......... T. subiasi Balogh, 1982. Distribution: Australia.
- Rostrum distinctly tripartite............................................................................ 2
2. Five pairs of genital setae; bothridial setae with well-developed lanceolate head and short cilia....................... 3
- Four pairs of genital setae; bothridial setae pectinate.......................................................... 5
3. Costulae short, diagonally oriented; humeral regions with narrowly triangular processes; body size: 332–348 × 166–174................................................................... T. alpina sp. nov. Distribution: New Zealand.
- Costulae elongated, longitudinally oriented; humeral regions absent or not narrowly triangular........................ 4
4. Notogastral cristae very long, reaching the insertions of setae h 3; humeral regions with large tubercle-like processes; body size: 337–365 × 194 – 171................ T. algicola (Golosova & Karppinen, 1983) comb. nov. Distribution: Sakhalin Island.
- Notogastral cristae short, not reaching the insertions of setae h 3; humeral regions without processes; body size: 415–448 × 215–249........................................................ T. frigida sp. nov. Distribution: New Zealand.
5. Anterior of notogaster with one pair of medial tubercles...................................................... 6
- Anterior medial margin of notogaster without medial tubercles................................................. 7
6. Distal parts of costulae parallel; bothridial branches with cilia; body length: 490............................................................................................ T. traegardhi Hammer, 1968. Distribution: New Zealand.
- Distal parts of costulae curving medially; bothridial branches simple; body length: 340.......................................................................................... T. aokii Hammer, 1968. Distribution: New Zealand.
7. Bothridial setae with very short branches (obviously shorter than interlamellar setae); body length: 630............................................................................ T. dalenii Hammer, 1968. Distribution: New Zealand.
- Bothridial setae with distinctly long branches (similar to interlamellar setae in length).............................. 8
8. Distal parts of costulae parallel; lamellar setae distanced from distal parts of costulae; body length: 550......................................................................... T. forsslundi Hammer, 1968. Distribution: New Zealand.
- Distal parts of costulae curving medially; lamellar setae inserted nearly to distal parts of costulae; body length: 490–500....................................................... T. tarraswahlbergi Hammer, 1968. Distribution: New Zealand.