Size and growth
Adult Ceratogyrus brachycephalus reach about 11–13 cm (4.25–5 in) and are fast growers. Adult Ceratogyrus darlingi reach about 12–14 cm (4.75–5.5 in) and are fast growers. That affects how quickly Rhino Horned Baboons and Rear Horned Baboons move through sling and juvenile enclosure sizes.
Do not use size alone to estimate age in either Ceratogyrus brachycephalus or Ceratogyrus darlingi. Sex, feeding and individual variation can change the pace of growth even when two spiders began at a similar size.
Enclosure and lifestyle
Rhino Horned Baboons are fossorial, while Rear Horned Baboons are fossorial. Build the Ceratogyrus brachycephalus enclosure for a fossorial spider and the Ceratogyrus darlingi enclosure for a fossorial spider instead of assuming two tarantulas need the same shape of setup.
For Ceratogyrus brachycephalus, substrate depth, retreat position and usable space should match its fossorial lifestyle. Apply the same rule separately to Ceratogyrus darlingi; the enclosure should make normal behaviour easy rather than forcing either species into a generic layout.
Temperature, water and moisture
A practical temperature range for Ceratogyrus brachycephalus is 21–27°C; for Ceratogyrus darlingi, it is 21–27°C. Stable room conditions are more useful for both species than chasing small fluctuations within those ranges.
For Ceratogyrus brachycephalus, keep a mostly dry setup with surface with a modest lower moisture gradient and a water dish. For Ceratogyrus darlingi, keep a mostly dry setup with surface with a modest moisture gradient below; provide water and ventilation. In both enclosures, keep fresh water available and adjust substrate moisture to how quickly the setup actually dries.
Temperament and maintenance
Ceratogyrus brachycephalus is an Old World species, while Ceratogyrus darlingi is an Old World species. That background is useful when planning maintenance, but individual Rhino Horned Baboons and Rear Horned Baboons can still differ noticeably in speed and defensiveness.
With both Ceratogyrus brachycephalus and Ceratogyrus darlingi, locate the spider before opening the enclosure, use long tools when they make the job safer and keep a catch cup ready for rehousing. Handling is not required for routine care.
Male and female lifespan
Male Ceratogyrus brachycephalus generally live roughly 2–4 years, while females can live 8–12 years. Male Ceratogyrus darlingi generally live roughly 2–4 years, while females can live 8–12 years.
Those lifespan ranges make sex particularly relevant when comparing Ceratogyrus brachycephalus with Ceratogyrus darlingi. A confirmed female of either species is normally a much longer commitment than a mature male, and the exact age of an older juvenile may be impossible to know.
UK availability and trade notes
In the UK hobby, Ceratogyrus brachycephalus is currently classed as rare, while Ceratogyrus darlingi is classed as uncommon. Stock changes between specialist sellers, captive-produced batches and show weekends, so availability should be checked at the time of purchase.
For records and purchases, use the scientific names Ceratogyrus brachycephalus and Ceratogyrus darlingi as the main identifiers. Current trade notes list Ceratogyrus brachycephalus as 'Check current CITES rules before cross-border trade' and Ceratogyrus darlingi as 'Check current CITES rules before cross-border trade', so check current requirements before any international movement where controls may apply.
Practical difference in day-to-day care
The practical difference between Ceratogyrus brachycephalus and Ceratogyrus darlingi comes from the combination of lifestyle, adult size, growth and moisture needs. Those factors change how much substrate, vertical space and maintenance access each enclosure needs.
Whichever species you keep, let the individual spider settle into an enclosure designed for its own biology. That applies equally to Ceratogyrus brachycephalus and Ceratogyrus darlingi: fresh water, secure housing and patient observation matter more than trying to make the two species behave the same way.