phosphanes

The saturated hydrides of tervalent phosphorus having the general formula P_nH_n+2 . Individual members having an unbranched phosphorus chain are named phosphane, diphosphane, triphosphane, etc. The name of a saturated hydride of phosphorus wherein one or more phosphorus atoms have a bonding number of 5 is formed by prefixing locants and $λ 5$ symbols to the name of the corresponding phosphane. Hydrocarbyl derivatives of PH₃ belong to the class phosphines.

Source:

PAC, 1995, 67, 1307 (Glossary of class names of organic compounds and reactivity intermediates based on structure (IUPAC Recommendations 1995)) on page 1357