Paulasterias undetermined

Mah, Christopher, Linse, Katrin, Copley, Jon, Marsh, Leigh, Rogers, Alex, Clague, David & Foltz, David, 2015, Description of a new family, new genus, and two new species of deep-sea Forcipulatacea (Asteroidea), including the first known sea star from hydrothermal vent habitats, Zoological Journal of the Linnean Society (Zool. J. Linn. Soc.) 174 (1), pp. 93-113 : 105-108

publication ID	https://doi.org/ 10.1111/zoj.12229
persistent identifier	https://treatment.plazi.org/id/03CA878C-FF82-226D-5589-FEC1FDA6EFFA
treatment provided by	Carolina
scientific name	Paulasterias undetermined
status

Treatment

PAULASTERIAS MCCLAINI GEN. ET SP. NOV.

FIGS 7–8 View Figure 7 View Figure 8

‘Six-rayed pedicellasterid’ Mah & Foltz, 2011b: 649–653, 658; Figs 2–3 View Figure 2 View Figure 3 .

Etymology

This species is named for Dr Craig McClain, NESCENT, Duke University, who invited the lead author to

participate in the 2009 Pacific Northwest MBARI expedition.

Taxonomic comments

The surveyed literature revealed no other comparable Indian or Pacific taxa. Three Atlantic pedicellasterid species, Hydrasterias ophiodon (Sladen 1889) , Hydrasterias sexradiatus (Perrier in Milne- Edwards 1882), and Ampheraster alaminos Downey, 1971 possess six arms. The skeletons of these three taxa lack a fleshy body wall, however, and are relatively well developed, with strongly expressed reticulation across the disc and arms, compared with that of P. mcclaini gen. et sp. nov., which is reduced to weakly expressed, with widely dispersed irregular reticulation. Marginal plates and accessory spines are observable in Ampheraster and Hydrasterias , but are not observable in P. mcclaini gen. et sp. nov.

ECOLOGICAL NOTES

Unlike P. tyleri View in CoL gen. et sp. nov., specimens of P. mcclaini View in CoL gen. et sp. nov. were not collected from active hydrothermal vent regions, but from adjacent or proximal settings displaying related geological activity (e.g. Clague et al., 2013 for Axial Seamount; Damm et al., 2006 for Gorda Ridge). As indicated under the ‘Material examined’ section, some specimens were collect- ed 0.2 km away from active vent regions, whereas others were collected more distantly. Specimens were collect- ed from both soft bottom and rock substrates. These areas included pillow lavas covered by fine sediments and vent chimney fragments. One specimen (USNM 1138787) was collected from an area covered by yellow, hydrothermally altered clays interspersed with white bacterial mat.

No direct evidence of feeding (e.g. gut contents) was present, but stomachs in at least two of the specimens were slightly distended and one specimen was observed to have a slightly depressed disc relative to the arms, suggesting that its stomach was extended to the substrate. It is possible that P. mcclaini View in CoL gen. et sp. nov. is a detritivore or perhaps feeds on the bacterial mats present in the area.

Occurrence

CoAxial North Seamount, Juan deFuca Ridge; ‘North Cleft’ pillow mounds, Gorda Ridge south to Taney Seamount, North Pacific Ocean, 2257.9–3321.8 m.

Description

Arms six, slender, elongate; disc small. Body strongly stellate (R / r = 6.4–14.4).

Abactinal skeleton strongly minimized, especially in the smaller specimen. Larger specimens with thicker, fleshier skin. In smaller individuals, body surface paperthin on dried specimens.Abactinal skeleton nearly absent except the primary circlet on the disc, carinal plates expressed weakly and other tiny plates irregularly occurring on arms. Body surface covered by a layer of fleshy, spongy tissue, obscuring plates in wet and unprepared dry specimens. Plates observed best in dry specimens and obscured in living or wet-preserved individuals. Primary plates, polygonal, relatively large present inter-radially, forming part of circular series with smaller, rod-like plates extending between primary circlet plates. Within the primary circlet, a series of smaller, rod-like plates extends to the disc centre, forming an irregular curve. Some minor, smaller quadrate plates present at disc centre. Carinal plates present weakly, each carinal plate lobate with four basal projections or sometimes irregular in shape with a spine present on the centre surface of each plate. Carinals not directly articulated with primary circlet and weakly in contact in series along arm. Carinal plates slender, overlapping. Thicker, more broad-based plates occurring regularly along carinal series where spines are present. Slender, but irregularly shaped plates in short series of ossicles forming weakly transverse ribs. Spines with jagged tips.Abactinal plates particularly diffuse adradially, becoming more defined closer to the marginal plate series. Reticulation widely spaced, with prominent single papulae present within plate openings. Pedicellariae covered by pustular sheaths, occurring in the fleshy, dense covering on body surface.

Papulae not observed. Madreporite large, pentagonal in outline, strongly convex with well-developed sulci. Madreporite thick and sitting above the plane of the body surface. Basal madreporite region with spines.

Pedicellariae, three types present. Largest (length ∼ 1 mm) pedicellariae, straight with between three and five jagged teeth on each valve, occuring heavily on the inter-radial disc but also along the arm ( Fig. 8C, D View Figure 8 ). Second largest pedicellariae wrench-like, with curved valves bearing small low-profile teeth ( Fig. 8A,B View Figure 8 ), most abundant covering abactinal and lateral surfaces of arm. Smallest sized pedicellariae are straight and occur in furrow at the base of each spine on each adambulacral plate. These are similar in shape to the large, straight pedicellariae, but more triangular in shape with fewer teeth.

Marginal plates in incomplete series and obscured by fleshy tissue, with individual plates often not in direct contact but appearing to be in a discontinuous series along lateral side to arm tip. Individual plates irregular in shape, some cruciform, others polygonal to lobate. Some marginal plates directly in contact with adambulacral plate series. Superomarginals relatively small, sometimes absent, especially in small individuals, cruciform to diamond in outline in weakly defined series. Sometimes, when present, with a single short pointed spine. Inferomarginals trilobate in shape, each bearing a spine, easily between two and four times larger than superomarginals, always present, overlapping onto adambulacral plate series. Inferomarginal spines short, blunt round in cross section. Large straight pedicellariae, equivalent in size and adjacent to inferomarginal spine.

A series of single flattened imbricate plates extend from the primary plates inter-radially from the abactinal to the actinal surface, but absent in smaller individuals. Actinal clusters of plates composed of five or six plates, some bearing a sharp spine and/or a large straight pedicellariae, bearing multiple teeth on each valve. Small gaps present between actinal plates filled with skin. Papulae absent from actinal surface.

Furrow spines, one or two (mostly one) per adambulacral plate, each with jagged tips. These spines covered by fleshy, sacculate sheath. Single spines present on first two adambulacral plates, remaining plates each with two spines. Small furrow pedicellariae present (described above). Adambulacral plates wing-shaped, with tissue-filled spaces between plates. First adambulacral plates not in direct contact.

Cardiac stomach extended, muscular. Tube feet biserial.

Colour of animal in life: white to light reddish orange. Material examined

USNM 1231370 About USNM Holotype: Gorda Ridge, GR-14 Seacliff Vent Field site, from 42.755725, −126.710512 to 42.755738, −126.71052, 2771.3–2771.5 m. Collected about 0.2 km from active venting, with black smokers and Ridgeia sp. present, coll. D. Clague, MBARI, aboard RV Western Flyer , using ROV Tiburon 8/23/2005 T884 A14+A15 (one wet specimen, R = 5.7 cm, r = − 0.6 cm). GoogleMaps

USNM 1231371 About USNM Paratype: Gorda Ridge , GR-14 Seacliff Site, from 42.755725, −126.710512 to 42.755738, −126.71052, 2771.3–2771.5 m. Collected about 0.2 km from active venting, with black smokers and Ridgeia sp. present. Coll. D. Clague GoogleMaps , MBARI, aboard RV Western Flyer , using ROV Tiburon 8/23/2005 T884 A14+A15 (one dry specimen, R = 7.2 cm, r = 0.5 cm).

USNM 1138789 About USNM Paratype: CoAxial North seamount, North Pacific, 46°31′00″N, 129°34′22″W, 2430.2 m, coll. Clague / McClain GoogleMaps , MBARI, aboard RV Western Flyer using ROV Doc Ricketts D 78-A4, 31 Aug, 2009. DNA sample CLM 314 (one wet specimen R = 3.5 cm, r = 0.4 cm).

USNM 1138787 About USNM Paratype: North Cleft ‘1986 Pillow mounds’, North Pacific, 45°1′54.1″N, 130°10′50.5″W, 2257.9 m, coll. Clague / McClain GoogleMaps , MBARI, aboard RV Western Flyer using ROV Doc Ricketts, D 80-A1, 2 September 2009, DNA sample CLM D320 (one dry specimen, R = 2.4 cm, r = 0.2 cm).

USNM 1138788 About USNM Paratype: NESCA clam site, North Pacific , 41°0′43.7″N, 127°29′28.5″W, 3321.8 m, coll. Clague / McClain GoogleMaps , MBARI, aboard RV Western Flyer using ROV Doc Ricketts, D 83-A10, 5 September 2009 (one wet specimen, R = 2.9 cm, r = 0.45 cm)

Further occurence observations

Taney Seamount, 36.849706, −125.592912, 2840.6 m, ROV Doc Ricketts, 8 August 2010, Dive D174-A30; Taney Seamount 36.839267, −125.607463, 2427.1 m (images, but no specimen collections verified).