There are two grape varieties with this name:
The red grape variety is a new breeding between Chatus (Nebbiolo di Dronero) x Dolcetto. Synonyms are Dalmasso 7-21, Incrocio Dalmasso VII/21 and S. Martino. According to DNA analyses carried out in 2009, the breeding list entry Nebbiolo x Dolcetto was wrong. The cross was made in 1936 in Conegliano (Veneto) by the breeder Giovanni Dalmasso (1886-1974). Incidentally, the same parents also produced the new varieties Passau and Valentino Nero. The variety is cultivated in Piedmont. In 2016, 6 hectares of vines were reported with a falling trend (Kym Anderson).
The glossary is a monumental achievement and one of the most important contributions to wine knowledge. Of all the encyclopaedias I use on the subject of wine, it is by far the most important. That was the case ten years ago and it hasn't changed since.
Andreas Essl
Autor, Modena