Seal finger (sealer’s finger, spekk finger), an extremely painful hand infection contracted by individuals handling seals, has previously been associated with Mycoplasma phocacerebrale. From 2000 to 2014, six independent strains of a novel Mycoplasma species were isolated at Statens Serum Institut, Denmark, from Scandinavian patients with seal finger (M5725^T, M6447, M6620, M6642 and M6879) or septic arthritis (M6921). Prior to the onset of infection, all patients had reported contact with unspeci-ated seals. All isolates grew within 2–5 days in Friis’ modified broth and metabolized glucose and arginine but not urea. Strains M5725^T, M6447, M6642 and M6921 also grew in Hayflick-type media. Colonies on agar media were large (0.5–1.0 mm) and had a typical ‘fried egg’ appearance, reduced tetrazolium, and were digitonin sensitive. Growth occurred at 32 °C but not at 42 °C. Strains were susceptible to doxycycline and moxifloxacin but resistant to azithromycin and erythromycin. The genomes of the six strains were sequenced and relatedness to all known Mycoplasma species was inferred. Phylogenetic analyses using 16S rRNA gene sequences and core genome single nucleotide polymorphisms showed that the isolated strains were highly similar and phylogenetically distinct from all other species within the genus Mycoplasma. The sizes of the genome sequences of the strains ranged from 744 321 to 772409 bp, with a G+C content of 25.0–25.2 mol%. Based on these analyses, we propose a novel species of the genus Mycoplasma with the name Mycoplasma phocimorsus sp. nov. with the first isolate M5725^T (NCTC 14922^T=DSM 116188^T) as the proposed type strain and representative strains M6447, M6620, M6642, M6879 and M6921.