It was Schoff that mentions the species. The author himself considers the gum resin to possibly be frankincense but doesn't mentions what specific type it is
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He is saying that it's not myrh that they found but frankincense. Altogether very suggestive of frankincense
They have done a chemical analysis to confirm things, so his preliminary examination is correct. And it's the same species mentioned.
Holy Smoke in Medieval Funerary Rites: Chemical Fingerprints of Frankincense in Southern Belgian Incense Burners - PMC
Frankincense, the oleogum resin from Boswellia sp., has been an early luxury good in both Western and Eastern societies and is particularly used in Christian funerary and liturgical rites. The scant grave goods in late medieval burials comprise ...
pmc.ncbi.nlm.nih.gov