Peniagone cf challengeri Théel, 1882

Peniagone cf challengeri Théel, 1882 View in CoL

Figure 4a, b, Appendix 1, Table S1

Material examined. NMV F308151 About NMV (1) [IN 2022 V 08 105] .

Diagnosis of IOT material. Single small, elongate specimen, 32 mm long, 10 mm wide and 5 mm high (preserved). Light pink and soft before preservation, light grey to white and firm once preserved (ethanol). Quite damaged, outer skin looks stripped and “fluffy” and preserved specimen was stripped of most appendages. Anterior end downturned with ventral tentacle crown. Two long tapered dorsal anterior lobes visible on damaged velum. Tube feet where visible on preserved specimen were free and restricted to posterior section, though live photo shows a potential brim of partly fused appendages. Posterior mid-terminal incision in preserved specimen, but not obvious in shipboard photo so may be an artifact. Minimal ossicles but all Peniagone - type crosses with four long spinous arms, long bare central stem, and four short and spinous apophyses.

Remarks. Identified here as closest to Peniagone challengeri Théel, 1882 based on the morphology described, particularly the ossicles (which match the illustration for the type specimen of P. challengeri in Théel, 1882), bifid velum, posterior tube feet and elongate form, but too damaged to identify further than Peniagone cf challengeri .

Distribution. This specimen lot only: Indian Ocean, Australian IOT, Christmas Island Territory, Balthazar Seamount Stn., 2298–2435 m.

Full bathymetric range. 2298–2435 m.

References. AFD (2024), ALA (2024), Cross et al. (2009), Hansen (1975), O’Loughlin (1998), Rowe et al. (2017), Théel (1882).

Peniagone coccinea Rogacheva and Gebruk in Rogacheva et al., 2013

Peniagone coccinea Rogacheva and Gebruk View in CoL in Rogacheva et al., 2013: 608–610, figs 13, 14, 18h, i, o, 19e (online supplement 1).— Gebruk et al., 2014: 162.— Kremenetskaia et al., 2021: 14, fig. 9.

Material examined. NMV F296857 About NMV * (1) [IN 2021 V 04 028] ; NMV F308183 About NMV (1) , NMV F308188 About NMV * (1) and NMV F308189 About NMV (2) [IN 2022 V 08 115] .

Diagnosis of IOT material. Bright pink to red and gelatinous with semitransparent skin (live), cream to grey with pink tinge

(preserved, ethanol). Body form elongate, raised dorsally and broadening towards the posterior end. Most complete preserved specimen up to ~ 70 mm long, 20 mm high and 20 mm wide ( NMV F308183, fig. 5a). Anterior dorsal velum with two pairs of long papillae fused at the base on each side (central ones longer). Mouth downturned on short neck tube with flaccid tentacles extended, only six remaining on the most complete specimen. Posterior with a brim of small, fused tube feet and dorsal anus. Skin is soft and easily damaged. Ossicles of body wall are flat, irregular, variably spinous crosses (fig. 5b–f), and two kinds of Peniagone - type crosses, all with smooth (or minutely spinous) central beams, some with irregular extra branches. One version of Peniagone - type cross with mostly wide but inward-curving spinous arms and four (3–4) shorter straight, almost vertical spinous apophyses (fig. 5i–k). Other type with mostly four outward-curving arms, quite irregular in length and shape and often strongly spinous at ends, with mostly four short, thick spinous apophyses (fig. 5l–o). Tentacles, tube feet, velum (and occasionally body wall) with additional irregular spinous rods, straight to curved (fig. 5g, h).

Remarks. Colour and brim like Peniagone cf azorica above, but ossicles are distinctive and have the more “irregular” form of P. coccinea Rogacheva and Gebruk in Rogacheva et al., 2013.

Distribution. North Atlantic, Indian Ocean (Australian IOT).

Full bathymetric range. 2600–2974 m (IOT 2760–2974 m).

Type locality. North Atlantic , Mid-Atlantic Ridge south of the Charlie Gibbs Fracture Zone, 2600–2750 m .

This species not previously recorded from Australia in AFD or ALA (January 2024) .

This IOT material represents a geographic range extension for the species and a small increase in depth range.

References. AFD (2024), ALA (2024), Gebruk et al. (2014), Rogacheva et al. (2013).