Austropolaria, Neal, Barnich, Wiklund & Glover, 2012

Neal, L., Barnich, R. & Wiklund, H, 2012, A new genus and species of Polynoidae (Annelida, Polychaeta) from Pine Island Bay, Amundsen Sea, Southern Ocean-a region of high taxonomic novelty, Zootaxa 3542, pp. 80-88 : 82

Austropolaria n. gen.

Type species. Austropolaria magnicirrata n. gen. n. sp.

Diagnosis. Body short, flattened dorsoventrally, with up to 20 segments. Elytrophores reduced, 9 pairs, on segments 2, 4, 5, 7, 9, 11, 13, 15, 17 (presence of elytra not confirmed); cirrigerous segments with large dorsal cirri with prominent cirrophores. Prostomium with median antenna, without eyes and frontal filaments. Tentaculophores achaetous. Pharynx with 7 pairs of distal papillae. Dorsal tubercles indistinct. Parapodia biramous; noto- and neuropodia with elongate acicular lobe; tips of noto- and neuroacicula penetrating epidermis. Notochaetae stout, serrated along convex margin; neurochaetae more slender, with distal part flattened and serrated along lateral margins. Ventral cirri inserted subdistally on neuropodia. Posterior end with ventral keel.

Etymology. The generic name Austropolaria (Latin for southern pole) refers to the geographical area where the first representatives of the genus were found.

Remarks. The single median antenna and the noto- and neuropodia with projecting acicular lobes are characters of Austropolaria n. gen. which place this genus into the subfamily Macellicephalinae Hartmann- Schröder, 1971, revised by Pettibone (1976). The distinctive characters of Austropolaria n. gen., which separate it from other genera in Macellicephalinae are: seven pairs of pharyngeal papillae, nine pairs of reduced elytrophores, ventral cirri inserted subdistally on the neuropodia, and a ventral keel at the posterior end.

The new genus might be confused with Bathypolaria Levenstein, 1981 which has a ventral keel posteriorly and seven pairs of pharyngeal papillae whereas Austropolaria n. gen. has nine pairs of reduced elytrophores and up to 20 segments. Unfortunately, the type material of Bathypolaria carinata Levenstein, 1981 seems to be lost, since it could not be found in the collection of the Shirshov Institute of Oceanology in Moscow (pers. comm. N. Budaeva and T. Britaev). The original description and the number of animals investigated by Levenstein are sufficient to conclude that adult specimens of this species do not have more than eight pairs of reduced elytrophores and 15 segments. Additionally, several formalin-preserved specimens identified as Bathypolaria carinata were received from the University of Aveiro, Portugal. These were collected in the deep Nazaré Canyon, Iberian margin, NE Atlantic. Although this is not a type locality, these specimens clearly show the characters of Bathypolaria and in absence of a type specimen are the best available material for morphological comparison. Two formalin-preserved specimens identified as Bathypolaria carinata were also received from University of Fairbanks, Alaska. Although from the type locality, these specimens were in very poor condition for any meaningful morphological examination.

Together with Bathypolaria and Natopolynoe Pettibone, 1985b , the new genus described here has reduced elytrophores and subdistally inserted ventral cirri, while in other Macellicephalinae elytrophores are well developed and ventral cirri are inserted basally on the neuropodia. Natopolynoe however is clearly different owing to its small rounded posterior end and higher number of pharyngeal papillae. Austropolaria , Bathypolaria and Levensteiniella Pettibone, 1985b are up to now the only known Macellicephalinae with 7 pairs of pharyngeal papillae. The differences of Austropolaria and Bathypolaria have been discussed above and Levensteiniella may be distinguished by its 11 pairs of elytrophores and small rectangular posterior end. Apart from Natopolynoe , two further genera have 9 pairs of elytrophores, i.e. Macellicephala McIntosh, 1885 and Bathykermadeca Pettibone, 1976 . As for Natopolynoe , these two differ by the shape of their posterior end and the number of pharyngeal papillae. The comparison of the genera and characters discussed are summarized in Table 1. An updated key to all known genera within the Macellicephalinae is presented below.

DNA: Preliminary analyses (not shown) conducted on a limited number of polynoid sequences indicate that the genus Natopolynoe is closely related to Austropolaria , and the genus Macellicephaloides is the sister taxon to that clade. However, the sequences available for a phylogenetic study of the Macellicephalinae group and its relatives are yet very few, and until more taxa have been sequenced, the relationships within the group remain unresolved. The DNA extraction from available formalin-preserved material of Bathypolaria was unsuccessful.