Is that a record from Roots Ireland - a pay site?
It isn’t covered here
https://registers.nli.ie/parishes/0899?locale=enDo you have other records,though, which confirm his mother as Boyce.
Do you have his military record?
I see that Fold3 has these two records:
Denis Lynch, Sergeant
Pension Age 39 yrs (abt 1837)
Birthplace Adare, Limerick
Pension Date 5th Sept 1876
Regiment:57 Foot
RegimentalNo. 2952
Denis Lynch
Rank G. (gunner?)
Pension Age 44 yrs
Birth Date abt 1835
Birthplace Ballingarry, Limerick
Pension Date 25th Feb 1879
Regiment Coast Bde Arly R. A.(Royal Artillery?)
Regimental Number 3740