The 39-year-old man, identified by police only as José Ramón L.A. faces charges of homicide through neglect after the body of his mother was discovered at his Tenerife home.
Health workers were appalled to discover the state of the woman, Ana Delia A.M when emergency services were called to her home after her death was reported, according to a report in local paper La Provincia.
A team from Cecoes 112 found the woman curled up in a foetal position with visible signs of neglect, including ulcers all over her body from lying in the same position for long periods, and obvious starvation.
She weighed just 25 kgs (55 pounds).
The woman lived with her son and his wife, who has also in police custody.