Pachymerellus zygethus is a species of centipede in the Geophilidae family.

It is endemic to Australia and New Zealand, and was first described in 1920 by American biologist Ralph Vary Chamberlin.

[1][2][3] This species features small denticles on the forcipular coxosternite and tarsungula, no sternal pores, and scattered coxal pores; the second maxillae have claws with small filaments.

[4] The original description of this species is based on a specimen measuring about 35 mm in length with 55 pairs of legs,[1] but the number of segments in this species can range from as few as 47 to as many as 65.

[3][5] The centipedes are solitary terrestrial predators that inhabit plant litter, soil and rotting wood.