Scientific name
Haplophthalmus danicus
Haplophthalmus danicus is a small white to beige woodlouse bearing longitudinal ridges on its back. BMIG distinguishes these ridges from those of other closely related Haplophthalmus. [1]
Origin
British records describe it mainly in the south-east, with scattered observations as far as southern Scotland and in Ireland. The Natural History Museum holds, among others, an adult specimen collected in Wales in 2021. [1][2]
- Small woodlouse
- Moist decomposed wood
- Natural-history profile
Natural history profile; a complete captive protocol is not established by the sources consulted.
At a glance
Haplophthalmus danicus is a tiny pale woodlouse with longitudinal dorsal ridges, to be distinguished from closely related species of the same genus. [1]
| ADULT SIZE | Up to 4 mm BMIG reference point; not newborn size. [1] |
|---|---|
| LIFESPAN | Not established No supported individual lifespan in the selected sources. |
| LIFESTYLE | In moist debris Rotten wood, peaty material and compost. [1] |
Adult size
Up to 4 mm in the BMIG overview; this limit does not give the size of newborns. [1]
Lifespan
Individual lifespan not reported by the documents retained.
Lifestyle
Associated with moist rotten wood, peaty debris and compost in well-vegetated sites. [1]
Housing
NATURAL ENVIRONMENT
Moist wood and debris — Documented natural environments; no terrarium volume or setup validated. [1]
No minimum volume or terrarium arrangement is validated by the two references retained. Its small size requires distinguishing an observation project from an enclosure claimed to be escape-proof without testing.
Care parameters
CAPTIVE CLIMATE
Not established — No validated husbandry range in the selected sources.
Humidity
Damp natural environment — Decomposed wood and moist debris; no captive percentage instruction. [1]
Environmental moisture
Documented moist microsites. [1] No domestic relative-humidity percentage inferred.
Temperature
No captive instructions retained. Environmental descriptions and collection data are insufficient to define a heating protocol.
Identification
Magnification useful for ridges and sexual characteristics. [1] Document visible characteristics and keep the identification provisional if the criteria cannot be examined.
Feeding
DIET AND CALCIUM
Decomposed wood and compost are observation sites; the documents define neither a complete menu nor protein or calcium quantities. [1][2]
Scope of this profile
Natural history profile; a complete captive protocol is not established by the sources consulted.
Recognising the genus and species
The body has a continuous outline, and each eye is reduced to a black ocellus. H. danicus lacks the pair of pronounced projections on the third abdominal segment found in H. mengii and H. montivagus. [1] An unclear general photograph may therefore allow less than a certain species identification.
Sexing: an anatomical characteristic
The male bears an upward-pointing spur on the carpus of the seventh leg. [1] This characteristic must not be replaced by an assumption based on size. The absence of a usable view simply allows sex to remain unknown.
What a museum specimen contributes
The Natural History Museum record indicates an adult, hand-collected at Nantgarw Colliery in December 2021, whose sex is not recorded. [2] It provides a traceable occurrence; it is neither a breeding profile nor proof of tolerance of every condition present in that region.
Feeding and substrate
Decomposed wood and compost are documented observation sites. [1] The selected documents do not allow a complete menu, a protein quantity or a feeding schedule to be inferred from them. A supplement used for a large Porcellio does not become a prescription for this species by simple analogy.
Breeding, growth and lifespan
No series followed from birth to reproduction is used here. Durations and usual brood size therefore remain unreported. The small adult size also explains why measurement alone is insufficient to declare an individual a new juvenile.
Using this profile
Its primary purpose is to help recognise and understand the animal. A captive project requires additional documentation on the strain, diet and keeping conditions. For monitoring, retain original photographs with a scale and distinguish confirmed identification from a provisional identification.
Checklist
- Compare the ridges with closely related species.
- Keep a scale in photographs.
- Seek a species-specific protocol before establishing a culture.
Observations to record
- Photographs with a scale
- Identification and sex
- Microhabitat
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Sources
Document-based overview; not a substitute for veterinary advice.