Catherine verch Rhydderch ap Sion of Abergynolwyn ¹

   Another name for Catherine was Catherine verch Rhydderch Sion.

  Research Notes:

From Reifsnyder-Gillam Ancestry, 45-46:

"Hugh ap David married Catherine, daughter of Rhydderch ap John, of Abergydolwyn, Merionethshire. According to deeds in possession of descendants, Catherine must have been born about 1584, and have been the eldest child. There is extant a marriage settlement showing that Rhydderch ap John, of Abergydolwyn, in the county of Merioneth, and Marianne, daughter of Owen ap David ap Lewis, were married in the first part of 1583. Hugh ap David and Catherine, daughter of Rhydderch ap John, were married about 1600-1603."

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From Wikipedia - Abergynolwyn :
Abergynolwyn (English : Mouth of the River with a Whirlpool) is a village in southern Gwynedd , Wales , located at the confluence of the Nant Gwernol and the Afon Dysynni . Historically, the village was part of Merionethshire and its main industry was slate quarrying

Local features
Llyn Mwyngil (Tal-y-llyn Lake)
The mediaeval Welsh castle of Castell y Bere near Llanfihangel-y-pennant (built by Llewellyn the Great in 1221)
The Iron Age fort on Craig yr Aderyn (Bird Rock).

Catherine married Hugh ap David of Llwyn du, Llwyngwrill, Llangelynin, Talybont, son of David ap Howell ap Goronwy of Llwyn du, Llangelynin, Talybont and Mary verch Hugh ap John of Tal y Llyn, about 1600-1603 in Llwyngwril, Llangelynin, Merionethshire, Wales. (Hugh ap David of Llwyn du, Llwyngwrill, Llangelynin, Talybont was born about 1566 in Llwyn du, Llwyngwrill, Llangelynin, Merionethshire, Wales and died before 1 Jan 1649.)

  Marriage Notes:

From the book Reifsnyder-Gillam Ancestry, Edited by Thomas Allen Glenn at the request of Howard Reifsnyder, privately printed, Philadelphia, 1902, provided by http://books.google.com, p. 45:

"Hugh ap David and Catherine, daughter of Rhydderch ap John, were married about 1600-1603."

Another source has abt. 1599 in Llwyngwril, Merionethshire, Wales.