Sibogaster nieseni

• Main Author: Mah, Christopher L.
• Format: Other/Unknown Material
• Language: unknown
• Published: 2016
• Subjects: Biodiversity; Taxonomy; Animalia; Echinodermata; Asteroidea; Valvatida; Goniasteridae; Sibogaster; Sibogaster nieseni; Luke; Pacific; North Atlantic
• Online Access: https://zenodo.org/record/6055262; https://doi.org/10.5281/zenodo.6055262

Sibogaster nieseni nov. sp. Figure 11 A–E (North Pacific), 12A–E (Indonesia), 13A–E (Atlantic) Luke 1982: 15; Maluf 1988: 34, 119 (as cf. Sibogaster sp.) Etymology. This species is named for Professor Thomas Niesen, Professor Emeritus of Marine Biology, San Francisco State University. Comments. Specimens of Sibogaster nieseni n. sp. were first brought to the attention of the author via specimens collected by MBARI, but as museum collections were reviewed, it was determined that this specimens of this species had been collected as early as 1966 (Luke 1982: 15) from collection in the Pacific and the Atlantic. This species was placed into the genus Sibogaster based on the shared smooth abactinal and marginal plate surfaces as well as shared actinal granulation and similarity in furrow spine number and morphology. As indicated below, specimens from several widely occurring localities in the Pacific and the Atlantic were identified. Morphological differences between individuals was slight, including similar to identical numbers of furrow spines (six to six or eight), actinal granules ranging from round to round with pointed tip, to minor variation in presence/ absence of pedicellariae on marginal plates. Other characters were mostly identical, abactinal and marginal plates were bare with coarse granules between them and body shape was largely similar. Differences were similar to those observed in other widely occurring species, such as Hippasteria phrygiana (Mah et al. 2014) or in species of the deep-sea Porcellanasteridae (e.g. Madsen, 1961a). The Indonesian specimen (IE- 2013-6809) shows perhaps the most significant differences relative to the other specimens in that the abactinal accessory and actinal granules are pointed and spinelet-like. Also dissimilar is the presence of granules on several of the interradial marginal plates which then trail off in number, the plates becoming bare along the arms. This species is unusual for the Goniasteridae in that it occurs well below 2000 m (lower Bathyal zone). Most ...