They're certainly not Sumatran.
They're all Indian Elephants mainly. Although Indali's part Sri Lankan via her maternal great grandmother (Ceyla at Zurich). So is Elizabeth via her paternal grandmother (Romani at Syracuse).
My dear Zoochat fellows, how many times do we have to highlight and correct this adagium and take it with a little more salt than we currently do so matter-of-fact like!
Indeed and fair enough, Sri Lankan elephants have a peculiar history where Sri Lankan elephants seem actually distantly related to those from Myanmar ... (with known trade routes and introduction from there to Sri Lanka)! Further, the cut off point for Sri Lankan from mainland elephants is put at only 48,000 years ago - in evolutionary terms - quite young and very recent (where usually very little genetic divergence of bloodlines develops nor exists). So whereas Sri Lankan elephants are yet recognised as a separate subspecies..., the jury on the (accumulated) data are still out.... and even now some of our greatest taxonomists of our age(s)!
PERSONAL INTERJACTION NOTE: Unfortunately till quite recently biodiversity and taxonomy had taken a backseat to microbiology and genetics/DNA and not the age old study of natural history, evolution, speciation and taxonomics and cladistics ..., well here speaks personal frustration ..... and mindboggling incomprehension at this lack of concern and focus on biodiversity - TBH the loss of which is actually our Major All Over-Arching Crisis, not Economic Development nor Climate Change or Nitrogen Crisis locally ...I know)!!!
Safe to say, it would be advisable to perhaps maintain Sri Lankan and Indian subcontinent origin elephants separate ..., but that is actually running in front of current research and what conclusions may be taken away from the most recent genetics studies. However, a current study (2025, in progress on captive Asiatic elephants in European zoos) seems to confirm that there are 4 subspecies ... at the very least (yet, it is far from ad finitum).
Personally, I am inclined to consider that Indian / Sri Lankan elephants may actually be genetically from the same ESU given old as well as recent trade and traffic across and consequently may / might yet be re-arranged under the same subspecies cluster (however unlikely at this point ... this seems at present). Further (and consider this carefully): those straits between the southern states of Tamil Nadu, Kerala and Sri Lanka are not as huge as in other parts of Continental Asia and island archipelago S.E Asia (Sumatera or Kalimantan from mainland or the other islands within the Indonesia archipelago).
The old subspecific taxonomy rationale has been fully revised quite a while back and thankfully has given us actually more with the penultimate recognition of both Sumateran and Kalimantan elephants as island subspecies connected/restricted to their respective islands.
Further to research on this aspect, there may in future also be consequences for the subspecific status of mainland S.E. Asian, IndoChina (previously recognised as their own subspecies ...) and PR China elephants with further genetic research.
Links:
IUCN current subspecific taxonomic status
A)
IUCN Red List of Threatened Species
Recent research on specifically Sri Lankan elephants (wild + captive)
B)
Revisiting traditional SSR based methodologies available for elephant genetic studies | Scientific Reports
Current animal collection management / knowledge base
C)
https://wildlifesos.org/introducing-the-subspecies-of-asian-elephants/
Research in progress on European captive elephants: study under review and unpublished
D)
Genomics reveals distinct evolutionary lineages in Asian elephants