Is it anthocerus, like most Latin names?
heard as anthocerus
spelled anthoceros
No. This one ends -os: Anthoceros.
What the ear did
Nearly every genus name in a flora ends in -us, -a or -um, so -us is the reflex guess. Anthoceros kept its Greek ending untouched, which is unusual enough to be worth remembering on its own.
A-N-T-H-O-C-E-R-O-S
The full entry for anthoceros covers the name itself.