Astroglypha, Mah, 2021

Mah, Christopher L., 2021, The East Pacific / South Pacific Boundary: New taxa and occurrences from Rapa Nui (Easter Island), New Caledonia and adjacent regions, Zootaxa 4980 (3), pp. 401-450 : 418-419

Astroglypha n. gen.

Etymology. The genus is composed of the Greek “ Astron ” for star and the Greek “glypho” for “carved or engraved” alluding to the very sculpted appearance of both species.

Diagnosis. Body petaloid with short, blunt, arms. Disk and arm ossicles enlarged, convex and blocky forming three distinct series with carinal and superomarginal plates visible along each arm. Disk plates enlarged and blocky. Surface covered by continuous granulation. Adambulacral spines one or two. Large flattened bullet-shaped subambulacral spine present.

Type species. Tamaria pyramidata Mah n. sp.

Taxonomic Comments. Tamaria passiflora and the new species of Astroglypha n. gen. fall outside the historical Tamaria concept as outlined by H.L. Clark (1921) and are herein assigned to the new genus Astroglypha . The Ophidiasteridae has recently undergone re-evaluation following molecular data ( Mah & Foltz 2011) showing genera such as Fromia and Neoferdina to be members of the Goniasteridae . Mah (2017) examined the paraphyletic Ophidiasteridae and attempted to establish morphological boundaries for ophidiasterid-like Goniasteridae and more typological Ophidiasteridae , such as Ophidiaster or Linckia .

Tamaria has been historically defined on the basis of six serial papular rows contingent on the absence of actinal papulae, as compared with Ophidiaster (H.L. Clark, 1921) . However, in spite of the difference in papular rows, Tamaria , in Clark’s original (1921) definition shares more characters with more typological ophidiasterids, such as Ophidiaster (sensu Mah 2017) , such as the cylindrical arms, small disk and marginal and abactinal plate arrangement.

Tamaria passiflora was described by Downey (1971) with four papular rows as well as a more strongly developed skeleton, petaloid-shaped, shorter arms and a more weakly stellate body (R/r = approximately 3.0–4.0 versus 4.0–7.0 in spp. more similar to the type species) and large blocky marginal and disk ossicles. These features are inconsistent with characters identifying the traditional Tamaria concept as outlined by H.L. Clark (1921). Thus, it is argued that Tamaria passiflora and the species described herein should be separated as part of the new genus, Astroglypha . Clark & Downey (1992: 284) further discussed this species’ unusual morphology and agreed that “perhaps deserves to be removed to a new genus, on the basis of its single row of large abactinal plates, its irregular arrangement of actinal plates, two series of subambulacral spines, minute terminal plates and short, heavy petaloid arms.”

Astroglypha n. gen. within the Ophidiasteridae . Astroglypha n. gen. is provisionally placed within the Ophidiasteridae but further testing of affinities is encouraged. Most of the genera included in the Ophidiasteridae display characters which strongly support the more traditional ophidiasterid morphology. Hacelia , Heteronardoa , Linckia , Ophidiaster , and Tamaria display characters with cylindrical arms, small disk, granular coverings and show abactinal and marginal plates which are identical in appearance.

The newly described Astroglypha lacks morphological characters seen in other Ophidiasteridae , including having shorter arms, blockier abactinal and marginal plates and arms which are more angular in shape and angular rather than round in cross-section. However, marginal and abactinal plates are similar in appearance and the surface is covered by granules as is the case in other ophidiasterids. Thus, based on these characters, Astroglypha n. gen. is retained within the Ophidiasteridae . However, the morphology is otherwise highly divergent from the other known genera within the family with the possible exception of Bunaster , which displays similarly arranged abactinal and marginal plates ( Marsh 1999). Blake (2018: 60) illustrated skeletal similarities between Astroglypha (formerly Tamaria ) passiflora and Paleozoic Asteroidea , notably the Ordovician Hudsonaster and Macroporaster . In situ observation of Astroglypha passiflora in the tropical Atlantic ( Fig. 8F ) suggest this morphology could be associated with predation on sponges.

Figures

FIGURE 8. Astroglypha passiflora n. comb. USNM 1233542 (Yucatan Channel, Mexico): A. Abactinal surface. Scale bar equals 0.5 cm. B. Abactinal-lateral view. Scale bar equals 0.35 cm. C. Actinal surface. Scale bar equals 0.5 cm. D. Actinal-lateral view of marginal plate series. Scale bar equals 0.35 cm. E. Actinal view showing actinal spines and furrow spination. Scale bar equals 0.1 cm. F. In situ observation of A. passiflora from Puerto Rico, showing individual (not collected) adjacent to two sponges.