Leptothecata: Halopterididae In our 16S rRNA phylogenetic hypothesis of the Halopterididae, Antennella flava sp. nov. forms a sister-group relationship with A. secundaria (Gmelin, 1791) (Fig. 32), showing nevertheless a high genetic distance (11.4 ± 1.6%) from the latter, further supporting its establishment as a new species. As equally shown in Fig. 32, genetic data (16S rRNA) on the family Halopterididae are provided for the first time for A. sibogae (Billard, 1911b), as well as for Balinese specimens of Halopteris vervoorti Galea, 2008 and Polyplumaria cornuta (Bale, 1884), supplementing those obtained earlier (P. Schuchert, unpublished results; Galea et al. 2018; Galea & Maggioni 2020) for A. billardi Galea (in Galea et al.), 2021, H. diaphana (Heller, 1868), H. longibrachia Calder & Faucci, 2021, H. plagiocampa (Pictet, 1893), H. platygonotheca Schuchert, 1997 and H. polymorpha (Billard, 1913). 16S rRNA sequences of H. diaphana, H. plagiocampa, H. platygonotheca, H. vervoorti and P. cornuta cluster with conspecific sequences from other localities (Fig. 32). Finally, several Antennella secundaria -like colonies, white- to pale-green-colored and not morphologically separable from Gmelin’s (1791) hydroid were collected from the island, showing an overall high genetic divergence from each other (sequences OR872075, OR872076, OR872077, OR872078, OR872079, MF784533) and suggesting that the diversity of A. secundaria -like hydroids is currently underestimated (Fig. 32).

Published as part of Galea, Horia R. & Maggioni, Davide, 2024, On some tropical hydroids (Cnidaria: Hydrozoa), with descriptions of four new species, pp. 1-57 in Zootaxa 5428 (1) on page 47, DOI: 10.11646/zootaxa.5428.1.1, http://zenodo.org/record/10842930