The small, elongate centipedes of the genera Tasmanophilus
and the adventive Pachymerium ferrugineum
are difficult to separate without the aid of a microscope. Tasmanophilus
has one representative in New Zealand, T. spenceri
and several in Australia. It is very similar to these Australian species especially the Tasmanian T. opinatus
, although that is a much larger species. It is distinguished from Steneurytion
species by the shorter, subcircular/quadrate head and distinctive pits in the centre of the ventral plates of segments 2 to 13. These pits are at their largest on segments 6-9 (inclusive) and may not be always present on segments 2 or 11-13. The same ventral plates also have a small process (peg or paxillus) on their back edge at the centre and the nearby intervening area between two plates is depressed. The depression continues into the anterior margin of the next segment (fossa or sacculus) the two together forming the "carpophagus structure".
The shape of the head is a character which is used by some authors to separate the Geophilidae from the Chilenophilidae (respectively subcircular/quadrate or elongate/rectangular) which certainly includes the other three genera. The latter is often considered a subfamily of the former and this genus has been placed at times in either family: compare its placement in the Tasmania fauna
with the Australian checklist
which is followed here.
The species is relatively common in the south: in Fiordland across to Bluff, Stewart Island and its offshore islets and, perhaps surprisingly, on the Snares Islands (100 km south of Stewart Island).
However, there are several specimens from outside of this distribution pattern. These have ventral pits on sternites 3-17 and the "carpophagus structure" and represent a separate, possibly unnamed, species that is close to the Tasmanian Pachymerellus zygethus
, a species that is placed in the Geophilidae.