Micronephthys sp. 1

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

Micronephthys sp. 1

Diagnosis.

Small bodied specimens, 4-8 mm long for <30 chaetigers. Branchiae (or interramal cirri) absent. Prostomium with straight to slightly convex anterior margin, subpentagonal to round in shape; short, conical antennae inserted on distal margin slightly medial to anterolateral corners; palps single, short, conical, inserted and directed ventrally. Subdermal eyespots not visible. First chaetiger similar in size to following chaetigers, not reduced. Parapodial acicular lobes conical, aciculae with curved tips. Neuropodial superior lobes absent. Parapodial rami with four types of chaetae: barred chaetae present in preacicular position, spinose chaetae present in postacicular position; capillary chaetae present in neuropodia of chaetiger 1; and some finely spinulose (almost smooth) long capillary-like chaetae in postacicular position of notopodia on following chaetigers. Furcate (lyrate) chaetae absent; thick dentate chaetae absent from chaetiger 1. Some specimens with very long spinulose chaetae in mid and posterior chaetigers, so specimens perhaps in swimming phase. Small papilla-like dorsal cirrus present on inner posteroventral face of all notopodia. Dissected pharynx with pair of conical jaws, 20 bifid terminal papillae (none enlarged more than others), plus 20-22 longitudinal rows of subterminal papillae with more than eight long papillae per row, diminishing in size proximally, single elongate middorsal and midventral papillae absent.

Remarks.

These specimens agree with the emended diagnosis for the genus by Murray et al. (2015). There are currently 15 valid nominal species of Micronephthys ( Read and Fauchald 2020), of which only two species possess the combination of absence of both branchiae and lyrate chaetae (see Dnestrovskaya and Jirkov 2010, 2019): Micronephthys abranchiata Ehlers, 1913 and M. ambrizettana Augener, 1918. These species, however, have fewer papillae in the subterminal rows of pharyngeal papillae (4-6, cf.> 8 for IN2017_V03 specimens), and the latter species also possesses eyespots which the specimens herein do not. Without examination of type material of all Micronephthys species, the identity of specimens described above must remain unknown. Micronephthys MoV6847 (four stations, 203-1521 m) were recorded from the GAB ( MacIntosh et al. 2018: additional file 2) and further investigation is required to determine if the species from the GAB are the same as those from the present study.

Records.

71 specimens. Suppl. material 1: ops. 9, 16, 23, 27, 31, 33, 40, 54, 55, 79 (AM).