Leptothecata, Cornelius, 1992

Galea, Horia R. & Maggioni, Davide, 2024, On some tropical hydroids (Cnidaria: Hydrozoa), with descriptions of four new species, Zootaxa 5428 (1), pp. 1-57 : 42

Leptothecata : Sertulariidae

The 16S rRNA sequence of Tridentata borneensis Billard, 1925a from Bali did not match any other sequenced sertulariids, but clustered with other Tridentata species ( Fig. 28 ) in a well-supported clade (BPP = 1, MLBS = 89).

Tridentata loculosa ( Busk, 1852) has hydrothecae lacking the prominent, lateral, marginal cusps characteristic of the genus Tridentata , its hydranths are strikingly provided with a ligula, and its gonothecae (although transverselyringed) are closed by a watch-glass-shaped operculum ( Migotto 1996: 72), making it somehow distinct from members assigned to that genus so far. Additionally, the 16S rRNA sequence obtained from a Balinese specimen does not cluster with other Tridentata sequences, the latter forming a well-supported monophyletic group ( Fig. 28 ) also including a sequence of T. trigonostoma ( Busk, 1852) from Bali, which is identical to a conspecific sequence from Thailand.

Two other sertulariids, namely Idiellana pristis ( Lamouroux, 1816) and Diphasia mutulata ( Busk, 1852) , were also sequenced. The first clusters with a sequence of the same species from Thailand (with an intra-specific genetic distance of 0.4 ± 0.2%), whereas the second, here sequenced for the first time, is sister to all other Diphasia sequences included in the analyses, even though the support values for the genus are low ( Fig. 28 ).

Figures

FIGURE 28. Phylogenetic hypothesis of the family Sertulariidae based on the 16S rRNA region. Numbers at nodes represent BPP and MLBS, respectively.