A SNP which defines the Dinaric-South cluster has been identified. It is PH908 (position 14107064 C to T). It is inside a region which is not well covered by the Big Y test. Some Big Ys report 1-5 reads for 14107064 but because of the low number of reads this is not reported on FTDNA's Big Y pages and can only be seen with a YFull.com analysis or similar.
PH908 can be tested very reliably by traditional methods and it is available for order at YSeq.net ($17.50 plus a one-time DNA kit fee of $5 for your first test at YSeq):
(Note: in many cases it is not necessary to order PH908, please contact Bernie or Zdenko with any questions.)
Until now, there was no known SNP specific to Dinaric-South:
I-CTS10228 includes all Dinarics: all of Dinaric-North and all of Dinaric-South
The more specific I-S17250 group includes all Dinaric-South men but it also includes some Dinaric-North men.
Ten people from the I-S17250 haplogroup have received PH908 results from YSeq. Three of them are from different Dinaric-North branches of the I-S17250 haplogroup. All three Dinaric-North received ancestral PH908- results. Seven Dinaric-South men did the test, many were I-S17250* and others belonged to I-A356/Z16983. All Dinaric-South men received derived PH908+ results. As mentioned above, some Big Ys show a few reads for PH908. According to YFull, one Dinaric-South man in I-S17250* had 1 T read at PH908 and another Dinaric-South man in I-A356/Z16983 received 4 T reads (meaning derived/positive). Many Dinaric-North men in I-S17250 and in other branches of I-CTS10228 had only C reads: 1 C, 2 C, 5 C etc. And many Dinaric-South and Dinaric-North men had no reads for PH908.
These results confirm the placement of PH908 as shown in our colored I-L621 tree posted in this blog in August 2016 .
PH908 is not available for individual order at FTDNA but we will ask them to add it to their catalog and/or a SNP pack. PH908 is not yet part of the I2a-M423 SNP panel at YSeq but it can be ordered as an individual SNP at YSeq. As a reminder, YSeq results cannot be transferred to FTDNA.
Update October 7, 2016:
The YFull tree has been updated to v4.09 and it now includes PH908: https://www.yfull.com/tree/I-S17250/
YFull put one sample from P. Francalacci study (ERS256264 = #746/742) in the I-PH908* haplogroup. That means at least one of two Sardinian I-S17250 samples belongs to the Dinaric South cluster.