Hermadion Kinberg 1856

Genus Hermadion Kinberg, 1856, emended

Type species. Hermadion magalhaensi Kinberg, 1856

Diagnosis. Body dorsoventrally flattened, short, with up to 50 segments; in large specimens mid-dorsum not completely covered by elytra and short tail uncovered. Fifteen pairs of elytra on segments 2, 4, 5, 7, 9, 11, 13, 15, 17, 19, 21, 23, 26, 29, and 32. Prostomium bilobed, without cephalic peaks, with three antennae; lateral antennae inserted ventrally to median antenna; two pairs of eyes and a pair of palps present. Parapodia biramous, both rami with elongate acicular lobe; notopodia shorter and on anterodorsal side of neuropodia; neuropodia without supra-acicular process; tips of noto- and neuroacicula penetrating epidermis. Notochaetae stouter than neurochaetae, with numerous rows of spines and blunt tip; neurochaetae more numerous, with numerous rows of spines distally and unidentate tip.

Remarks. The genera Harmothoe and Hermadion were both established by Kinberg (1856) with Harmothoe showing lateral antennae inserted ventrally, a rather short body, and 15 pairs of elytra covering the dorsum completely, while in Hermadion lateral antennae are also inserted ventrally, but the body is more elongate, 15 pairs of elytra leave the middorsum and the posterior segments uncovered, and neurochaetae have rows of spines reaching to the tip. Unfortunately, the body length and the degree of coverage of the dorsum by the elytra are difficult to evaluate in younger specimens (or insufficient for identification of anterior fragments). Moreover, in neurochaetae the amount of surface covered by rows of spines is an inadequate character, since in both Hermadion and Harmothoe this varies within the same bundle: in uppermost neurochaetae rows of spines can reach almost to the tip, while in middle and lower neurochaetae there is always a distinct bare area below the tip. Some authors, like Bergström (1916), considered the differences insufficient and synonymized Hermadion with Harmothoe, while Augener (1932) regarded Hermadion as a valid genus. Our examination of the type material of Hermadion showed, that there are indeed additonal significant differences between these two genera: in Hermadion cephalic peaks are absent and the neuropodia have no supra-acicular process, but both structures are present in Harmothoe. For a detailed description of the characters of Harmothoe, see the revisions by Barnich et al. (2006) and Barnich and Fiege (2009) and Tables 1 and 2 below.

The following discussion of species referred to other genera either by earlier authors or in the present study is summarized in Table 3.

Malmgreniella, Polynoe, Subadyte: cf. Barnich and Fiege 2003; Hermadion: this study; Hermadionella: cf. Uschakov

1982).

* in Barnich and Fiege (2003) neuroacicula of Polynoe described as not penetrating, but re-evaluation showed that both, noto- and neuroacicula are penetrating.