APPENDIX 1.
Measurements of Gehennachelys maini comb. nov. Measurements are in cm and are estimated if preceded by a tilde (~).
| DMNH 2013-07-1942 | HMNS- 10-TM | DMNH 2013-07-0784 | DMNH 2013-07-1711 | DMNH 2013-07-0712 | |
| Carapace | |||||
| Length | 47.5 | 38.9 | ~27.2 | – | – | 
| Width | 40.8 | 34.3 | – | – | – | 
| Height | – | 11.4 | – | – | – | 
| Cervical scale | |||||
| Length | – | – | 1.6 | 1.0 | – | 
| Width | – | – | 4.4 | 1.9 | – | 
| Vertebral scales | |||||
| 1 Length | – | – | 4.0 | – | – | 
| Width | – | – | 8.1 | – | – | 
| 2 Length | – | – | ~6.7 | – | – | 
| Width | – | – | ~10.4 | – | – | 
| 5 Length | – | – | 4.2 | – | – | 
| Width | – | – | 5.9 | – | – | 
| Plastron length | – | 36.3 | – | – | – | 
| Bridge length | – | 18.3 | – | – | – | 
| Anterior lobe | |||||
| Length | – | 8.3 | – | – | ~8.1 | 
| Width | 16.5 | 13.1 | – | – | ~14.4 | 
| Median gular contact | – | – | – | – | 3.0 | 
| Median extragular contact | – | – | – | – | 0.9 | 
| Posterior lobe | |||||
| Length | 11.5 | 10.5 | – | – | – | 
| Width | 15.6 | 13.0 | – | – | – | 
APPENDIX 2.
Phylogenetic coding for Gehennachelys maini comb. nov. using the character matrix described in Phylogenetic Methods above from Rollot et al. (2022b), with parentheses indicating polymorphic states:
Gehennachelys maini comb. nov 00??????10 ?0?11???01 1????????? ?100??0100 0000101010 0????0??00 100????1?? 111??10000 (0&1)1111????1 ?0?02????? ?0100

