Halitholus spec.

Schuchert, Peter, 2018, DNA barcoding of some Pandeidae species (Cnidaria, Hydrozoa, Anthoathecata), Revue suisse de Zoologie 125 (1), pp. 101-127 : 124-125

Halitholus spec.

Fig. 18 A-C in part Leuckartiara octona . ‒ Mackie & Mackie, 1963: 68 [not L. octona ( Fleming, 1823) ]

Halitholus species I . ‒ Arai & Brinckmann-Voss, 1980: 48, figs 23-24.

Material examined: 1 female specimens, not in permanent collection; USA, San Juan Island , Friday Harbor, 48.54514° -123.01206°, depth 0.5 m; collection date 20.05.2011; DNA isolate 870; for GenBank numbers of sequences see Table 1 .

Remarks: This species was described by Arai & Brinckmann-Voss (1980) as Halitholus species I . They kept it distinct from H. pauper Hartlaub, 1914 on account of the lacking interradial gonad-fold connection and the smoother radial canals. However, the latter character appears not so convincing. As they also found a second similar morphotype (as Halitholus species II) they did not describe it as a new species.

I suspect that Halitholus species I and Halitholus pauper in Arai & Brinckmann-Voss (1980) are the same, but it is not clear if they are really conspecific with H. pauper from the Atlantic Ocean (see Schuchert, 2007 for description). In Atlantic H. pauper , the interradial tentacles are usually not fully developed and the deep interradial subumbrellar pockets as visible in Fig. 18A have not been reported. Good photographs and also DNA barcode sequences of the Atlantic form are needed to evaluate more precisely the specific identity of the present material.

Even though the present medusa had no distinct mesenteries ( Fig. 18A ), the only character that distinguishes the genus Halitholus from Leuckartiara , the 16S and COI sequences placed it close to Leuckartiara octona , type species of the genus ( Figs 8-9 ). The other Halitholus species used in the analysis, H. cirratus , did not cluster with the Halitholus from Friday Harbor, which casts some doubts on the validity of the genus.

Figures

Fig. 18. Halitholus spec., living animal. (A) Whole medusa. (B) Bell margin with tentacle bases. (C) Details of manubrium with gonad folds. Note the clearly visible oocytes.

Fig. 8. 16S maximum likelihood phylogenetic tree of Pandeidae species obtained with PhyML (GTR+G+I model) and based on 595 bp positions of the mitochondrial 16S gene. Node-support values are bootstrap values of 100 pseudoreplicates (shown only if > 70%). For more details see text and Table 1. Samples based on the polyp stage are indicated, all others are medusa samples.

Fig. 9. COI maximum likelihood phylogenetic tree of Pandeidae species obtained with PhyML (GTR+G+I model) and based on 664 bp positions of the mitochondrial COI gene. Node-support values are bootstrap values of 100 pseudoreplicates (shown only if> 70%). For more details see text and Table 1. Samples based on the polyp stage are indicated, all others are medusa samples.