Hyalinothricinae Fisher, 1911

Gale, Andrew S., 2020, The fossil record of the asteroid (Echinodermata) family Chaetasteridae Sladen 1889 and subfamily Hyalothricinae Fisher, 1911, Zootaxa 4858 (1), pp. 144-150 : 148

Subfamily Hyalinothricinae Fisher, 1911

Included genera. Hyalinothrix Fisher, 1911 ; Seriaster Jangoux, 1984 ; Tarachaster Fisher, 1913 ; Chaetasterina Hess, 1970 ( Mah & Fujita 2020).

Diagnosis. Abactinals small, paxillose, imbricating; supero- and inferomarginals small, of equal size. All external ossicles bear a tuft of densely packed, glassy spines, positioned on a raised central region.

Remarks. Hyalinothrix was removed from the Ganeriidae Sladen, 1889 and the subfamily Hyalothricinae placed in the family Asterinidae on the basis of molecular evidence, supported by some morphological features, notably the imbricating abactinal plates and the presence of paxillae similar to those developed in some asterinids ( Mah & Fujita 2020). The genus has well-developed, but small supero- and inferomarginals ( Fig. 2L ); the paxillose abactinal ossicles possess imbricating basal processes and form a tessellation around the large popular pores ( Fig. 2M ).

Figures

FIGURE 2. A, B, Arthraster dixoni Forbes, 1848, small individual, in abactinal (A) and actinal (B) views; Middle Turonian, Dieppe, France; Collection of Nicolas Cottard, Offranville, Normany, France. C–I, Chaetasterina gracilis Hess, 1970. Holotype (NMB Hess A 94), Upper Hauterivian, Neuchâtel, Switzerland, original of Hess (1970: figs 9–14, pl. 3: fig. 5); C, abactinal view; D, actinal view; E–G enlargement of abactinal ossicles; H, I, enlargement of adambulacrals (ad) and inferomarginal (im). J–M, Hyalinothrix sp., Recent, Philippines, AS Gale coll. J, actinal view; K, abactinal view; L, enlargement of ossicles of denuded ambulacral groove; M, enlargement of denuded abactinal surface.