Sinodillo sp. 'China' is a small, fast woodlouse that the trade has sold under at least five names: most sellers now call it Sinodillo sp. 'Vietnam', and older listings call it Merulanella sp. 'Vietnam' or 'Red Head'. I could find no formal description of it. Sellers put adults at 10 to 12mm, and it can roll into a tight ball. Care comes down to climate: hold it steady at 21 to 24°C, the band on my care panel, keep the humidity moderate with a damp side and a drier side, let air move through the tub, and give it a living substrate under plenty of leaf litter, with calcium always available. Our Sinodillo sp. 'China' isopods are captive-bred.
The name, and what sits behind it
The earliest record I found under any of its names is a keeper's write-up from November 2021, as Merulanella sp. 'Vietnam', which already doubted the genus. It has also gone by Merulanella sp. 'Red Head' and 'Red Side'. A hobby name list treats all of these, with Sinodillo sp. 'China' and Sinodillo sp. 'Vietnam', as one animal; its pages for the Sinodillo names date from October 2024. The same list says the 'China' came from the person who placed it in Sinodillo, who judged it most likely Chinese rather than Vietnamese, and that most sellers still use 'Vietnam'. So 'China' is a judgement, not a collecting record, and we have found no published locality for it. If you searched for a 'red head isopod', you may be after the Albanian pill woodlouse Armadillidium flavoscutatum 'Redhead', a different animal with drier care, covered in our Armadillidium flavoscutatum 'Redhead' care guide.
Sinodillo itself is a described genus. Kwon and Taiti named it in 1993, in a study of the woodlice of southern China, Macao and Hong Kong, and put it in the Armadillidae, the tropical pill bug family. They built the name from Sina, Late Latin for China, and -dillo, an ending many genera in that family share. Its type species, S. troglophilus (the name means cave-loving), and a second species came from one cave in Yunnan, in south-west China, and a third from under stones on a plateau at 1,600 to 1,800 metres. Three more were added in 2000, in a study of the woodlice of Yunnan, making six. Kwon and Taiti called Troglodillo, the genus our Sunset isopods are sold under, extremely close to it.
I have found no paper that places the trade animal in Sinodillo or matches it to any of the six, so the fair description is that it is sold as a Sinodillo. The name did not come from the 2025 revision of Merulanella either. Kästle and Regalado Fernández left Merulanella with three species, none in the hobby, and raised Ardentiella for two species from Myanmar; most of the colourful animals once sold as Merulanella, the Ardentiella morphs, now sit there as undescribed species. I found no mention of Sinodillo in their paper. The Dream isopod, a Merulanella in older listings and Spherillo sp. 'Dream' in our guide, is another animal the trade has moved between labels.
What it looks like and how big it gets
Sellers describe a bluish-grey to grey-brown back with a cinnamon-red head and red along the skirt-like edges, which is where 'Red Head' comes from, and one says a pied form has been isolated from it. The uncurled animals in our listing photographs are a glossy slate-grey to purple-grey, some finely flecked paler on the back, and none shows an obvious red head or rim. Colour seems to vary: the keeper who wrote up a first culture in 2021 found about half the animals with orange-red borders and orange antennae and the rest drab grey with little pattern.
In our photographs it is a compact, rounded oval, and two of them show one animal, a warmer amber-brown than the rest, rolled into a tight ball. That matches the genus it is sold under, which Kwon and Taiti described as able to roll up into a ball. The 10 to 12mm on my care panel is the sellers' figure: both sellers I found who give a size quote it. I have found no published measurement of the trade animal, and the three species described in 1993 measured about 5 to 7mm at most.
Behaviour and handling
Expect speed. The 2021 keeper found it very fast, more like a roach than an isopod, and a seller describes it racing about the set-up; another says it is active by day and night, more so at night. Open the tub inside a larger box, move animals with a soft brush and be ready for them to run. I have found no report of it climbing, so do not assume it climbs as the Ardentiella do, but a tight lid with fine mesh vents suits any isopod.
Setting up the enclosure
Temperature is the part to get right. The 21 to 24°C on my care panel is our house band, and it sits inside the two ranges sellers give: one says 17 to 26°C, another 20 to 26°C, adding that it does better slightly cooler than many tropical species. A third says keepers have had more success at about 21°C or below, so I would hold it steady at the bottom of the band and keep it well under 26°C, the top of both ranges. English homes average about 19°C through the heating season, below the band, so in winter a heat mat or heat cable on a thermostat, on the side of the tub, never underneath, will hold it at the bottom of the band. In summer, keep it out of direct sun and away from heat, and read how hot is too hot for isopods before a heatwave.
Humidity should be moderate, not tropical. My panel says 60 to 75%, the upper part of what sellers give (50 to 70% and 50 to 75%), and the way to get it is a gradient, not a wet box: keep about half the substrate moist under moss and bark, and let the rest run drier under the leaf litter so the colony can choose. Pair that with moving air. Stagnant, humid air kills isopods that need airflow, so fit fine mesh vents in two opposite walls so that air travels through the box, and never seal it; one seller recommends small holes on alternating sides for the same reason, and against mould.
The base I recommend is flake soil, white-rotted hardwood and organic topsoil, a few centimetres deep; one seller suggests 2.5 to 7.5cm, and nothing I read calls for a deep bed. Coir holds moisture but is no food for a substrate-eater, so leave it out. Top it with plenty of mixed broadleaf and bamboo leaf litter with cork bark or rotting wood for cover; the sellers list the litter and the wood as food too. A small tub does for a starter group, and our guide to how big a tub isopods need covers sizing as the colony grows.
Feeding
The diet is built on the leaf litter and rotting hardwood already in the tub. The two sellers who list foods add vegetables, fruit and a protein such as fish food, dried shrimp or dried insects, and one advises protein twice a week. Lift fresh food before it spoils. One also lists lichen, which is worth offering, though I have found nothing published that says any woodlouse needs it. Keep a calcium source in the tub at all times, as you would for any woodlouse: both sellers include one, and crushed oyster shell or limestone does the job.
Breeding
Sellers call it anything from a fair to a fast breeder, and none gives a brood size; I have found no published figure either. The biology is the usual woodlouse pattern: the female carries her eggs in a watery brood pouch under her body, and the young leave it alive, with six pairs of legs rather than the adult seven, as our guide to whether isopods lay eggs explains. For a breeding group, keep conditions steady, keep the gradient, feed a varied diet and give plenty of bark and litter for cover.
Who it suits
My care panel rates it easy; the sellers I read range from easy to moderate, and one calls it sensitive. Its food and substrate are the ordinary woodlouse ones; what it asks for is a steady, moderate climate with moving air, and two sellers say it does better cool. That makes it a good second or third isopod for a keeper who has kept a hardy species and can hold a tub steady through a British summer and winter, and a poor choice for a hot room or a sunny windowsill.
Frequently Asked Questions
Is Sinodillo sp. 'Vietnam' the same as Sinodillo sp. 'China'?
Yes, as the trade uses the names. A hobby name list treats Sinodillo sp. 'China', Sinodillo sp. 'Vietnam', Merulanella sp. 'Vietnam' and 'Red Head' as one animal, and most sellers use 'Vietnam'. The 'China' came from the person who placed it in Sinodillo and thought it most likely Chinese; we have found no published locality for it.
Is Sinodillo the same as Merulanella?
No. Sinodillo is a genus Kwon and Taiti named in 1993 for woodlice from Yunnan, and Merulanella is an older genus that the 2025 revision left with three species, none in the hobby. This animal was sold as a Merulanella before it was sold as a Sinodillo, and some listings still use the old name; I have found no formal description of it under either name.
How big do Sinodillo isopods get?
About 10 to 12mm as adults. That is the sellers' figure and the one on my care panel; I have found no published measurement of the trade animal. The three species described in 1993 measure about 5 to 7mm.
What temperature do Sinodillo isopods need?
About 21 to 24°C, the band on my care panel, held steady at the bottom of it. Sellers give 17 to 26°C and 20 to 26°C, and two say it does better cooler than many other isopods, so keep it well clear of 26°C and out of summer heat.
Do Sinodillo isopods roll into a ball?
Yes. Our photographs show one rolled into a tight ball, and Kwon and Taiti described the genus as able to roll up into a ball.
Are Sinodillo isopods easy to keep?
Fairly, once the climate is right. My care panel rates them easy and sellers range from easy to moderate; the things to get right are a steady temperature at the cool end of the band, moderate humidity with a gradient, and air moving through the tub.
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