| Name | Microthamnium longirostrum Thériot |
| Authorship | Thériot |
| Rank | Species |
| NomenclaturalStatus | NomLeg |
| Placed in | Microthamnium |
| Citation | 1926 Recueil Publ. Soc. Havraise Etudes Diverses 1925: 150 |
| Holdings | 1 Specimen held in the Harvard University Herbaria identified as Microthamnium longirostrum Thériot |
| Identification made in | [no date] (1) |