Phalacrostemma, Gunton & Kupriyanova & Alvestad & Avery & Blake & Biriukova & Böggemann & Borisova & Budaeva & Burghardt & Capa & Georgieva & Glasby & Hsueh & Hutchings & Jimi & Kongsrud & Langeneck & Meißner & Murray & Nikolic & Paxton & Ramos & Schulze & Sobczyk & Watson & Wiklund & Wilson & Zhadan & Zhang, 2021

Gunton, Laetitia M., Kupriyanova, Elena K., Alvestad, Tom, Avery, Lynda, Blake, James A., Biriukova, Olga, Boeggemann, Markus, Borisova, Polina, Budaeva, Nataliya, Burghardt, Ingo, Capa, Maria, Georgieva, Magdalena N., Glasby, Christopher J., Hsueh, Pan-Wen, Hutchings, Pat, Jimi, Naoto, Kongsrud, Jon A., Langeneck, Joachim, Meissner, Karin, Murray, Anna, Nikolic, Mark, Paxton, Hannelore, Ramos, Dino, Schulze, Anja, Sobczyk, Robert, Watson, Charlotte, Wiklund, Helena, Wilson, Robin S., Zhadan, Anna & Zhang, Jinghuai, 2021, Annelids of the eastern Australian abyss collected by the 2017 RV ' Investigator' voyage, ZooKeys 1020, pp. 1-198 : 1

Phalacrostemma sp. nov.

Diagnosis.

Opercular lobes completely fused to each other. 12 pairs of (broken) outer golden paleae with pointed tips and compact thecae with straight margins. One pair of inner paleae, their blades smooth, amber-coloured with tapering tips. Eight pairs of robust and tapering opercular papillae, not extending to tip of outer paleae. Two pairs of flattened nuchal hooks, with poorly developed limbs on concave side. Tentacular filaments absent. Pair of buccal flaps present. One pair of short and robust palps, not extending to operculum. Thoracic segment 1 with one pair of long and tapering neuropodial cirri. Thoracic segment 2 with one pair of broad triangular lateral lobes. Eight pairs of dorsal branchiae on chaetigers 2-9. Four parathoracic chaetigers (3-6) bearing notopodia with robust non-retractile lanceolate chaetae interspersed with fine capillaries and neuropodia with thin lanceolate chaetae interspersed with fine short capillaries. Cauda lost.

Remarks.

This single specimen from 1761-1770 m is different from the specimens of P. timoharai as it has only 12 pairs of outer paleae (but many are broken), only one pair of inner paleae, two pairs of nuchal hooks and non-retractile lanceolate notopodial chaetae on parathoracic segments 3-6 (see Zhang et al. 2020: fig. 10F). The specimen clearly belongs to a new species which was also confirmed by molecular data, but is too damaged to be described formally as a new species.

Records.

1 specimen. Suppl. material 1: op. 128 (AM).