Peniagone cf azorica Marenzeller

Peniagone cf azorica Marenzeller View in CoL von, 1892

Material examined. NMV F308267 About NMV * (7) [IN 2022 V 08 145] .

Other material. Peniagone azorica Marenzeller von, 1892 – off eastern Australia, NMV F241035 About NMV [IN 2017 V03 090 110]; NMV F240855 About NMV [IN 2017 V03 032 143] (identified by Mark O’Loughlin, 2018).

Diagnosis of IOT material. Damaged, fragile specimens. Elongate, dorsally raised and convex but ventrally slightly rounded to flattened. Anterior end downturned with ventral mouth on neck tube (not visible in photo) and only four flaccid tentacles remaining. Anus dorsal and terminal. Pink to orange before preservation, with a fragile, translucent brim (<10 mm wide) around the entire animal, extending to form a wider anterior velum of five fused papillae. Central two anterior papillae are longer, with all fused for most of their length. Tube feet where visible appear restricted to posterior third of the body, and almost fully embedded in the brim. Preserved specimens (ethanol) are grey and spongey with chalky skin, brim and fused velum either lost or reduced to stringy pieces and approximately six previously embedded larger tube feet appearing free, with only the series of minute posterior tube feet remaining fused. Ossicles in body wall include larger irregular spinous crosses (fig. 3b–d), with four or more flat to slightly curved arms (up to 455 μm long), and Peniagone - type crosses with arms and apophyses, both with smooth central beams. Peniagone - type crosses mostly two types, some with four arms and 2–4 (typically 4) high apophyses curved inwards (fig. 3g –h), others (more common in ventral wall) with irregular arms curved out and shorter thick, spinous apophyses (fig. 3f, i). Both types have spines (serrations) on both arms and apophyses. Tentacles with same and spinous supporting rods. Most complete preserved specimen from IOT ~ 105 mm long, 15 mm wide and 15 mm high. Likely same specimen as shipboard image which was ~ 145 mm long and 45 mm wide before preservation (fig. 3a).

Remarks. Ossicles combined with body shape and tentacles closest to original type description of P. azorica Marenzeller von, 1892 from the North Atlantic, and subsequently descriptions by Hansen (1975). Identified as Peniagone cf azorica here as whole-body brim including completely fused anterior velum and tube feet embedded in a posterior brim (as seen in IOT specimens) does not match the bipartite velum and free tube feet bordering entire ventral sole of the original description, Hansen’s (1975) descriptions, or those described more recently from the mid-Atlantic ( Rogacheva et al., 2013). Ossicles, colour and morphology of IOT specimens match at least two of the six specimens Mark O’Loughlin identified as P. azorica Marenzeller von, 1892 from Australian eastern abyssal stations, which had a brim and fused velum in shipboard images but lost these after preservation ( NMV Catalogue, 2018).

Distribution. These specimen lots: Indian Ocean, Australian IOT, Cocos (Keeling) Islands Territory, Cocos (Keeling) Stn., 3002–3078 m; Two comparative specimens noted above: off eastern Australia in East Gippsland Marine Park and off Byron Bay, 2562–3853 m.

Full bathymetric range. 2562–3853 m.

References. Gebruk et al. (2014), Hansen (1975), Hansson et al. (2001), Marenzeller von (1892), Rogacheva et al. (2013), Kremenetskaia née Rogacheva (pers comm., 2023), Théel (1882)