Phryssonotus burmiticus (Cockerell, 1917) was the first formally described millipede species in the mid-Cretaceous amber from northern Myanmar. Although it has been reassigned and redescribed several times, critical characters for a reliable placement of the species remain elusive. Here we provide detailed morphological characters of P. burmiticus on the basis of six well-preserved adults (five males, one female) and nine juveniles. The species has many similarities to extant species in many aspects, including the number of ommatidia, the number and arrangement of sensory trichomes, morphology and arrangements of body trichomes, and features of the trunk appendages. It differs from extant species by assemblage of numbers of ommatidia and trichome B. The new morphological interpretation indicates a long-term morphological stasis in this peculiar millipede group. (C) 2018 Elsevier Ltd. All rights reserved.