Astrotholus phasma Mah 2023, n. gen.
Astrotholus phasma n. gen. n. sp. FIGURE 5A–F Etymology The species epithet phasma is derived from the Greek for ghost or spirit, alluding to the strongly arched ghostlike shape of this species. Diagnosis Abactinal plates flat to mound-like surface covered by simple spinelets, 4–10 (Fig. 5B, C). Tra...
| Published in: | Climate of the Past |
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| Main Author: | |
| Format: | Other/Unknown Material |
| Language: | unknown |
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Zenodo
2023
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| Online Access: | https://doi.org/10.5281/zenodo.8090116 http://treatment.plazi.org/id/03C387E86622FFF6FF68E7CF82B8FDA2 |
| Summary: | Astrotholus phasma n. gen. n. sp. FIGURE 5A–F Etymology The species epithet phasma is derived from the Greek for ghost or spirit, alluding to the strongly arched ghostlike shape of this species. Diagnosis Abactinal plates flat to mound-like surface covered by simple spinelets, 4–10 (Fig. 5B, C). Transverse interradial plates similar in size to radial abactinal plates (Fig. 5C). Superomarginal plates approximately twice the size of the inferomarginal plates (Fig. 5E). Furrow spines webbed, pointed, 2 to 7 in palmate formation. Subambulacral spines with identical spination, 3 to 6 in a straight to weakly palmate comb, arranged in oblique to transverse position relative and set off from the furrow spine by a distinct space (Fig. 5D, F). Largest size among type series R =2.5. Comments This species represents the only known occurrence of the genus in the South Atlantic, and outside of the Southern Ocean region. As indicated in the description, this species also displays the arched body form and what appears to be eggs present around the oral region (Fig. 5F inset). If ultimately confirmed as a brooding species, it would join Kampylaster incurvatus as the second high-latitude asterinid to display this behavior. Occurrence South Atlantic, Burdwood Bank, Drake Passage and Ross Sea 339–528 m. Description Body stellate (R/r=1.2–2.0), strongly arched (Fig. 5A, B, C), disk thickened, actinal surface convex, arms triangular. Interradial arcs acute. Abactinal plates imbricate, polylobate, larger plates on disk, arm plates smaller, most <50% of the size, some close to 25% of the size of those on the disk (Fig. 5A, B, C). Plates mostly flat, larger plates weakly mound-like. Abactinal plates covered by simple spinelets, 4–10, widely spaced, arranged in single series or only along edge of each plate with central region devoid of spination (Fig. 5B, C, E). Shallow furrows present between plates. Interradial plates in distinct transverse rows between the radial abactinal arm plates and the superomarginal plates. Transverse ... |
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