Trachelipus mostarensis Isopods for Sale UK

Ten records exist. That is the entire occurrence database for this animal: ten preserved-specimen entries held by eight museums - New York, Berlin, Cambridge, London, Washington, Leiden, Helsinki and Frankfurt, which holds three of them - and the great majority tracing back to Karl Verhoeff's own material. He named it in 1901, as a variety rather than a species, from specimens labelled Herzegovina, and as far as those databases go nobody has knowingly found another since. Eight museums holding pieces of the same collection is not eight localities.

We are opening with that because it shapes everything else on this page. When you read that a species occurs in Bosnia and Herzegovina and Croatia, that sentence comes from an encyclopedia entry sourced to a single European database, reproduced downstream by observation sites that copy their text wholesale. There are no occurrence records from Croatia at all, and the Croatian and Slovenian national checklists do not list it.

The taxonomy is unsettled

Trachelipus mostarensis began life as a variety, not a species, and Verhoeff could not decide whose: he hangs it off Porcellio ratzeburgii on one page of the note that names it and off P. rathkii on the next. Species status came later. The brackets round Verhoeff's name are there because the animal has since moved out of Porcellio into Trachelipus, not because of the change in rank. The complication is the standard 1997 revision of the European Trachelipus. It recognised fifteen species as valid, made nineteen names new synonyms and left nine as doubtful - and this animal is not among the fifteen. So it went into one of the other two groups. We could not obtain the body of the paper to see which. The modern aggregate databases still list the name as accepted, so its standing is open. It is unresolved, and anybody claiming otherwise has not checked.

The epithet matches the city of Mostar and the type material is Herzegovinian, so the connection is hard to miss. No published source states it, though, so treat that as an observation and not an etymology.

None of which makes it a difficult animal to keep. Temperate woodlice are temperate woodlice, and the ones with thin paperwork behave much like the ones with thick paperwork. It only means that nobody can tell you in advance which end of a range this particular species prefers. Our Trachelipus care guide sets this species beside the other five we keep, most of which have rather more behind them.

What is actually known

A published size for this animal does not exist, and we have now read the original in order to say so rather than assuming it. The name was erected in 1901 in a four-page note in the Berliner Entomologische Zeitschrift - not in the Zoologischer Anzeiger paper usually cited for it, which does not mention the animal at all. Across those four pages Verhoeff gives no measurement of any kind. The 12 to 15mm you will see quoted, including on our own older copy, traces to vendor listings and nothing else. No description of its colour exists in the literature either. And no one has put a thermometer to the question of what these animals will bear.

What we have is a colony that has run here long enough to be self-sustaining, and the following, which is practice: around 20 to 25°C in an ordinary room with no supplemental heat, humidity in the 60 to 70% region, graded, with a dry end they use, 5cm of substrate beneath a thick bed of leaf litter, flat bark and stone to press underneath, and calcium left in permanently. Most of the feeding is done by white-rotted hardwood worked through the substrate.

Do not expect it to roll. Threatened, it goes flat and wedges itself into whatever gap is nearest, which is what the whole genus does instead of balling up.

Anybody after a well-documented animal should start elsewhere in the genus.

Dispatch days are Monday, Tuesday, Wednesday and Thursday. Pre-1pm next-day post, a punched pot on moist moss, doubled board around it, 20% over your count, and our word that the lot of them turn up alive.