Ryan Seacrest Now It's Official ... New GF Marks Territory

7/14/2014 8:04 AM PDT

Ryan Seacrest's Girlfriend -- Now It's Official ... New GF Marks Her Territory

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Someone peed all over Ryan Seacrest's leg at LAX this weekend, and she happens to be his latest hot blonde chick gf ... Shayna Taylor.

We're talking metaphorical urine -- but Ryan and the 23-year-old model were spotted on their way back from a fabulous vacay when a photog asked her, point-blank, about bagging Seacrest ... and she finally answered ... loudly and proudly!

We first spotted them together back in December, but neither ever publicly admitted dating. 8 months later something's changed.

Sources connected to the couple tell us they spent 2 weeks in Europe, so it was either one helluva vacation -- or she's got one helluva an ass. Or both.