this is close to C. scalpelliformes. The one small individual at the top clearly portrays it is C. scalpelliformes. But, the serration that is whitened seems to make the difference. If it is C. mexicana as identified by Dr Levi, it might be a new record to Gujarat waters????! Please try sending the samples to MARS (Marine Algal Research Station) of CSMCRI at Mandapam, Tamil Nadu for which permissions are to be obtained from CSMCRI (ICAR Institution) at Bhavnagar, Gujarat. This is fitting provided your samples are collected from west coast or any other coast of India.
Some links on its record from Tamil Nadu coast of India
your institute CMFRI has reported C. mexicana way back in 1969. CMFRI Bulletin No. 9.pp. 37. In fact this is Catalouge of reference collections..Besides, it has been reported from Andaman (North) C. mexicana f indica. Some prominent references are added for your kind information. Th
1. Krishnamurthy, V. And H.V. Joshi, 1969. A acheck list of Indian marine algae, Bhavnagar: Central salt and Marine chemical research institute. 36 pp.
2. Subramanian, D., 1991. Chaemotaxonomical studies in south Indian species of Caulerpa. Seaweed research and Utilization 16: 205 – 218.
3. Umamaheswara Rao, M. 1969. Catalogue of marine algae in the reference collection of the central marine fisheries research institute. Bulletin of CMFRI. 9 : 37 – 48.
C. mexicana (Sonder) J. Agardh. CMFRI – MA. 33. Rameswaram (Palk Bay); Krusadai Island (Gulf of Mannar).
4. Umamaheswara Rao, M. 1972. Coral reef flora of the Gulf of mannar and Balk bay. In: Proceedings of the first international symposium on corals and coral reefs.Mandapam camp. 1969. Cochin. Marine biological association of India. 217 – 230.
Ya it looks Caulerpa scalpeliformis and Reeta madam for your reference Caulerpa mexicana is available plenty in our Indian waters recently i reported C.mexicana var pluriseriata in Andaman waters.