Pentaceraster Doderlein 1916

Pentaceraster Döderlein, 1916 Döderlein, 1916: 424; 1936: 331; Clark and Rowe 1971: 55; A.M. Clark 1993: 310 (checklist) Diagnosis. Body stellate (R/r=2.0–3.0, seldom>3.0) with strongly arched disk, elongate, triangular arms. Distal abactinal, actinal and especially marginal plates covered with distinct, even-sized, projecting granules. Abactinal–lateral regions with distinctly reticulate plates showing well-defined pore areas. Primary plates with spines or conical tubercles arranged in longitudinal series in most species. Distal inferomarginal plates with an enlarged spine or conical projection in most species. Intermarginal pore areas weakly developed or absent. Modified from Marsh and Fromont (2020). Comments. Pentaceraster includes 15 species that occur widely throughout the Indo-Pacific. The diagnosis follows Marsh and Fromont (2020), but boundaries for the concept of Pentaceraster have not been tested or reviewed since their establishment (Döderlein, 1916, 1936). Other oreasterid genera, such as Poraster, and the typological Oreaster, differ from Pentaceraster by relatively few characters and invite additional scrutiny, especially as further data on variation among species within these genera has produced taxonomic overlap. For example, Doderlein’s key (1936) differentiates the Atlantic Oreaster from Pentaceraster by the presence of low dorsal spines, a character observed in highly variable Indo-Pacific species, such as Pentaceraster alveolatus or Pentaceraster mammilatus. Character variation among Pentaceraster species is similarly problematic, with several species displaying character variation that is at odds with established species concepts, particularly as outlined by Döderlein (1916, 1936).五角海星属（Pentaceraster） Döderlein, 1916 Döderlein, 1916: 424; 1936: 331; Clark and Rowe 1971: 55; A.M. Clark 1993: 310（名录） 鉴别特征：身体呈星形（R/r=2.0~3.0，极少＞3.0），盘部强烈隆起，腕足细长呈三角形。反口面、口面的远端区域，以及尤其是边缘骨板，均被清晰、大小均一的突出颗粒所覆盖。反口面-侧面区域具明显的网状骨板，且带有界限清晰的孔区。多数类群的初级骨板上的棘或锥形瘤突呈纵向排列。多数类群的下缘骨板远端具有一枚膨大的棘或锥形突起。缘间孔区发育较弱或缺如。本鉴别特征修订自Marsh与Fromont（2020）的研究成果。 讨论：五角海星属共计15个物种，广泛分布于印度-太平洋海域。本次鉴别特征参考Marsh与Fromont（2020）的研究，但自该属建立以来（Döderlein, 1916, 1936），五角海星属的分类界定尚未得到验证或修订。瘤海星科（Oreasteridae）的其他属类群，如Poraster属（Poraster）以及模式类群Oreaster属（Oreaster），与五角海星属的形态差异相对较少，亟需开展进一步的分类学研究；尤其当针对这些属内物种变异的后续数据显示存在分类学重叠时，这一问题更为突出。例如，Döderlein（1936）的检索表将大西洋Oreaster属物种与五角海星属区分开来的依据是前者具低矮的背棘，但这一特征在印度-太平洋区高度变异的物种中均有出现，如蜂窝五角海星（Pentaceraster alveolatus）和乳突五角海星（Pentaceraster mammilatus）。五角海星属内物种的性状变异同样存在分类学难题：多个物种的性状变异与已确立的物种界定标准相悖，尤其是按照Döderlein（1916, 1936）提出的标准时。