The influence of shipwrecked Spanish sailors from the Armada on the Irish population is minimal, for several reasons. First, most of the survivors that landed in Ireland were captured by pro-English forces or bandits. Many of the Spanish sailors were Galicians, who do not fit the swarthy stereotype of Spaniards. Many Galicians resemble the fairer Irish, as that part of Spain was originally Celtic speaking. Indeed, Galicians were among the Celts who settled in Ireland circa 500 BC. Third, the absence of Spanish surnames in Ireland would indicate, in a patrilinear society, that the Armada survivors represent any significant proportion of the Irish population. Contrast this with the relatively high frequency of Norman French and English surnames, reflective of the pre-Reformation Anglo-Norman invasions.
The presence of Mediterranean looking Irishmen and the genetic similarity of many Irish to the Basques represent settlement patterns that well predate the defeated Armada and even the birth of Christ. Ireland had inhabitants prior to the arrival of the Celts, who may have been akin to the Basques. Additionally, trade routes from the eastern Mediterranean extended into the British Isles, and Ireland was never out of touch with sailors, traders, and merchants from that area. These influences are more plausible explanations for the "Black Irish" than are Armada survivors.
Thanks for posting interesting stuff, Wallace T. I read that Basques have the highest percentage of negative blood type of any group.
Jacob's twin brother Esau had red hair. As did King David. There are a lot of red headed Jews and they aren't from Ireland. In fact, there are many Persian Jews with red hair who have a tradition that they decended from King David.