Data from: Delineating seagrass species in the genera Halodule and Halophila from Tanzanian coastal waters using ITS and rbcL DNA barcoding

The seagrass species in Halodule and Halophila may for several reasons be
considered as taxonomic complexes. They show close evolutionary
relationships, morphological plasticity, and share similar features making
misidentifications likely when morphological identification is applied. In
Tanzanian coastal waters, there is some uncertainty about the identity of
members of Halodule, particularly the existence of Halodule wrightii and
the species composition of the Halophila ovalis complex. This study used
morphology as well as internal transcribed spacer (ITS1 and ITS2) and
ribulose-bisphosphate carboxylase (rbcL) DNA barcoding to identify species
of Halodule and Halophila. Seagrass samples were collected during low
spring tides, from Tanzania’s coastal waters of Tanga, Dar es Salaam,
Mtwara, Mafia Island, and Unguja Island, from August 2020 to February
2022. Morphological diagnosis, phylogenetic analysis, and evolutionary
divergences inferred from the ITS gene supported the identification of
five species, namely Halophila ovalis, H. minor, and H. stipulacea, with
the first two forming the H. ovalis complex; as well as Halodule uninervis
and H. pinifolia. It is the first time that H. pinifolia is reported in
Tanzania. This is the first study reporting the delineation of seagrass
species in East African coastal waters using DNA barcoding coupled with
morphology.