Regarding species, generally, as noted above, the fabricator will utilize the lumber dominant in the region, simply because of economics. Southern Pine seems likely for your case. A telephone call to local laminators will increase your confidence. You may be lucky and find a laminator with an old-timer on staff who could tell you exactly what was common in the area at that time for that type of beam. The exception is complex glulam beams or structures such as radially reinforced or highly detailed architectural masterpieces. Since the effort input into the furnishing of beams for such jobs is quite a bit more than simple beams, laminators from across the country or Canada may have been competitively bidding or incorporated into the design and build process. In such a case you may have lumber from the West Coast, and then Doug Fir would be likely.
The size does not seem to me to be a standard size. But the fact that it isn't standard is not bad, it's just not helpful to you to determine the species. Whereas 5-1/8" width is standard for DF today, they can be obtained in 5" 5-18" 5-1/4" and 5-1/2". I have a research paper from the 60s in my file which tested 9" thick DF glulams, and this is definitely not a standard size today. Thickness of laminations can be a clue, but it also is not infallible. SYP lams are typically 1 3/8" (from memory on this one, perhaps it's 1 5/8") and DF is typically 1-1/2". But I recently inspected an older structure with 10 DF laminations in 9". As I understand it, the "5" in V5 does not refer to number of laminations but rather it is simply a number, but it refers to a specific combination regulated by AITC etcetera. The laminator building a beam to V5 combination must utilize specific grades of lumber varied through the depth of the beam to produce the design values advertised, such as "the outer 15% must be high tension capacity lumber ft = x, the next 15% must be such and such, the inner 40% must be such and such... etc". The "V" as noted above indicates Visually graded lumber.
A piece of wood from the beam can be sent to a lab for accurate species determination if desired. I believe the Univ of Wisconsin still offers this service, likely others too.
Glulams have been around a long time and if it's a standard beam in a standard building and not older than the 60s, I think AITC started around 1952ish) I'd be pretty comfortable assuming it corresponds to the AITC.
Good luck!
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