School of Life Sciences, University of Hawai'i, Honolulu, HI, United States of America.
Department of Biodiversity, Western Australian Herbarium, Conservation and Attractions, Kensington, WA, Australia.
PLoS One. 2020 Jul 7;15(7):e0234358. doi: 10.1371/journal.pone.0234358. eCollection 2020.
Survey cruises by the National Oceanic and Atmospheric Administration (NOAA) in 2016 and 2019 yielded specimens of an undetermined red alga that rapidly attained alarming levels of benthic coverage at Pearl and Hermes Atoll, Papahānaumokuākea Marine National Monument, Hawai'i. By 2019 the seaweed had covered large expanses on the northeast side of the atoll with mat-like, extensive growth of entangled thalli. Specimens were analyzed using light microscopy and molecular analysis, and were compared to morphological descriptions in the literature for closely related taxa. Light microscopy demonstrated that the specimens likely belonged to the rhodomelacean genus Chondria, yet comparisons to taxonomic literature revealed no morphological match. DNA sequence analyses of the mitochondrial COI barcode marker, the plastidial rbcL gene, and the nuclear SSU gene confirmed its genus-level placement and demonstrated that this alga was unique compared to all other available sequences. Based on these data, this cryptogenic seaweed is here proposed as a new species: Chondria tumulosa A.R.Sherwood & J.M.Huisman sp. nov. Chondria tumulosa is distinct from all other species of Chondria based on its large, robust thalli, a mat-forming tendency, large axial diameter in mature branches (which decreases in diameter with subsequent orders of branching), terete axes, and bluntly rounded apices. Although C. tumulosa does not meet the criteria for the definition of an invasive species given that it has not been confirmed as introduced to Pearl and Hermes Atoll, this seaweed is not closely related to any known Hawaiian native species and is of particular concern given its sudden appearance and rapid increase in abundance in the Papahānaumokuākea Marine National Monument; an uninhabited, remote, and pristine island chain to the northwest of the Main Hawaiian Islands.
2016 年和 2019 年，美国国家海洋和大气管理局（NOAA）进行的调查巡航在夏威夷帕帕哈瑙莫夸基亚海洋国家纪念碑的珍珠和赫尔墨斯环礁采集到了一种未确定的红色海藻标本，其底栖覆盖范围迅速达到惊人水平。到 2019 年，这种海藻已经覆盖了环礁东北侧的大片区域，形成了带有纠缠的叶状体的垫状、广泛生长的藻席。使用光学显微镜和分子分析对标本进行了分析，并与文献中密切相关的分类群的形态描述进行了比较。光学显微镜表明，这些标本可能属于红藻门的角叉菜属，但与分类学文献的比较显示没有形态匹配。线粒体 COI 条码标记、质体 rbcL 基因和核 SSU 基因的 DNA 序列分析证实了其属级别的分类地位，并表明与所有其他可用序列相比，这种海藻是独特的。基于这些数据，这种隐源性海藻被提议作为一个新种：Chondria tumulosa A.R.Sherwood & J.M.Huisman sp. nov. Chondria tumulosa 与所有其他 Chondria 物种不同，其特点是具有大型、粗壮的叶状体、形成垫状的倾向、成熟分支的轴向直径较大（随着分支的后续顺序直径减小）、圆柱形轴和钝圆形顶端。尽管 Chondria tumulosa 不符合作为入侵物种的定义标准，因为尚未确认其被引入珍珠和赫尔墨斯环礁，但由于其在帕帕哈瑙莫夸基亚海洋国家纪念碑中的突然出现和迅速增加，这种海藻与任何已知的夏威夷本地物种都没有密切关系，并且由于其在西北的主夏威夷群岛之外的无人居住、偏远和原始的岛屿链上的突然出现和迅速增加而特别令人关注。
