Ahuastra Mah, 2024, nov. gen.

Ahuastra nov. gen. Etymology The genus name is composed of the Hawaiian word for mound, ahu alluding to the strongly convex shape of the adults of this species plus the feminine Latin word “astra” alluding to “star.” Number of species: Ahuastra gfoei (Mah, 2022) nov. gen. nov. comb., Ahuastra kupanaha n. gen. n. sp. (type) Diagnosis Body shape variably pentagonal to stellate (R/r=1.3–2.6), thick. Abactinal plates composed of two separate areas, a distinct papular area with well-developed fasciolar grooves with pentagonal to irregular polygonal plates; remainder of disk and arm plates round to irregularly polygonal. Abactinal plates with granules, variable in size, some plates with bald central surface with granular periphery, some completely covering plate surface. Superomarginal plates covered by spiny granules, blocky in shape, present on abactinal surface in both known species. Inferomarginal plates covered by spiny granules, forming lateral edge, which is covered by knife-shaped spinelets, more prominent when observed alive. Comments It was not until a second species, Ahuastra kupanaha n. gen. n. sp., was discovered that morphological characters supporting a novel taxon could be established. Ahuastra n. gen. is similar to Litonotaster in that the abactinal surface in both genera are composed of circular to irregularly polygonal, abutted, flat plates. However, disk shape, including the high-aspect, the position of the marginal plates, with wider, nearly equidistant (L=W) shaped interradial marginal plates as well as having spines/spinelets present along the lateral edge of the inferomarginal plates are significantly different from the typological Litonotaster, L. intermedius, which has a relatively weakly arched abactinal surface, and superomarginal/inferomarginal plates which are more lateral-facing, have more tumid superomarginal plate surfaces with a rounded actinolateral-edge, and are more elongate interradially. Spinelets are absent from the actinolateral edge along the inferomarginal plates in known Litonotaster species. Granular cover in Litonotaster intermedius is consistent over the entire abactinal surface but irregular on Ahuastra n. gen. Different species within Litonotaster show differing levels of affinity with Ahuastra n. gen., Litonotaster tumidus Ludwig 1905 demonstrates more affinity with Ahuastra kupanaha n. gen. n. sp. than with Ahuastra gfoei (Mah 2022). Litonotaster tumidus lacks the spination along the actinolateral fringe and abactinal granulation is spinose (more round in Ahuastra n. gen.) but it does have a small papular region with enlarged plates similar to those in Ahuastra n. gen. Phylogenetic tests are desirable in order to more fully delineate taxon boundaries.