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 : Haleciidae

According to the 16S rRNA phylogenetic reconstruction, Halecium turbinariae sp. nov. is divergent to all other sequenced congeners, thus supporting its establishment ( Fig. 29 ).

Halecium halecinum var. minor Pictet, 1893 , originally described based on sterile material, reminds Linnaeus’ (1758) species through the regularly pinnate structure of its colonies. The species was rediscovered in Bali, although the available specimens are equally devoid of gonothecae. However, upon comparison with a profuse, fully fertile, female colony of H. halecinum ( Linnaeus, 1758) from Britanny, France, it is realized that Pictet’s hydroid builds less robust colonies, with comparatively slenderer internodes, and the regular occurrence of a moderately-long, tubular, athecate internode at the origin of its cladia is distinctive. The two 16S rRNA sequences obtained from Balinese specimens are divergent from Atlantic H. halecinum sequences ( Fig. 29 ), also showing a genetic distance of 11.6 ± 1.4%. Based on both morphological and genetic evidence, the so-called variety is raised to species, as H. minor , nov. status.

Additionally, one newly-obtained and two unpublished 16S rRNA sequences of Halecium sibogae Billard, 1919 form a fully-supported monophyletic group with minimal intra-specific distance (0.1 ± 0.1%) ( Fig. 29 ).

Figures

FIGURE 29. Phylogenetic hypothesis of the genus Halecium based on the 16S rRNA region. Numbers at nodes represent BPP and MLBS, respectively.