St. Laurent Grape--Chasing Down a Mystery Parentage

Our friends treated us to dinner al fresco and brought with them a Michael Cruse St. Laurent Pétillant Naturel (Pét Nat), a sparkling wine made in the ancestral style.
I had never heard of the St. Laurent grape so I did a little research into what that is and here is what I came up with.
First, I turned to the Internet and learned from Wine.com that featured Michael Cruse's sparkling made from the St. Laurent that the grape is a high quality Austrian grape. The label on the back of the bottle informed me that the grapes were sourced from Ricci Vineyard in Carneros. Ok, that's a start. I wanted more.
When I Googled St. Laurent, and looked at Wikipedia I found that the grape could also be called Sankt Laurent and is generally believed to be a natural crossing between the Pinot Noir grape and some unknown partner.
That's when I turned to my goto book, the grape Bible, Wine Grapes¹ and while looking in the index, could not find St. Laurent. Wikipedia did mention that Sankt Laurent was a synonym and that's what I found in the index. Sankt Laurent whose principal synonyms include Sankt Laurent, Laurenzitraube, Laurenztraube and Saint-Lorentz Traube in Austria, Saint Laurent and Schwarzer in Germany, Saint-Laurent in France, Svatovavřinecké and Vavřinecké in the Czech Republic and Svätovavrinecké in Slovakia. What Jancis Robinson and her co-authors said about the Sankt Laurent is that the DNA profile is genetically distant from Pinot Saint-Laurent. This was not what I read on Wikipedia.
I was interested to know if the Ricci Vineyard Website had any information about the St. Laurent grape that went into Michael Cruse's sparkling Pét Nat: In 2000-2001, Ricci Vineyards imported budwood from the last known St. Laurent vineyard in Germany. They currently have 6 acres planted in this variety. The genetic parentage is not clarified on their website because this is what they say:
"St. Laurent is a mysterious grape in its origins and ancestry, but has found a dedicated foothold in the wine growing regions of the Czech Republic, Austria, and other assorted pockets around the world. Bordering between the fringes of a Burgundy and Rhone varietal, St. Laurent could best be described as Pinot Noir with sultry underpinnings. "
One last try, a suggestion from my husband. If the St. Laurent was brought into the U.S., it would have had to undergo testing at Foundation Plant Services so there should be some information there. Indeed, there is.
This is what is written under the information for St. Laurent: This variety is today commonly planted in Austria and Germany. DNA results have shown a parent-offspring relationship with Pinot noir. Since the initial budwood from Ricci vineyard came from Germany, it does appear that it is related to Pinot noir, but it would be very nice if Ricci Vineyards could do a DNA test to see if indeed their St. Laurent really is related to Pinot noir.
References:
1. J. Robinson, J. Harding and J. Vouillamoz, Wine Grapes - A complete guide to 1,368 vine varieties, including their origins and flavours, ppg 958- 960 and 962-964, Allen Lane 2012 ISBN 978-1-846-14446-2.