ABSTRACT

Phragmope discrepans (Lithothamnion discrepans) is recognized as a new monotypic genus endemic to South Africa on account of several active modes of growth, including apical meristem replacement, production of cell bars in canals of multiporate conceptacles, and development of a second compact, imperforate roof over multiporate conceptacles. Meristem replacement involves up to three layers. Development of cell bars starts with production of projecting cells from basal cells of lining filaments, and these cells subsequently coalesce to form a barrier. Subepithallial divisions produce a second compact roof that is composed of 1–2 perithallial cells and a layer of epithallial cells. It is assumed that these novelties reflect evolutionary advancements to overcome competition and the environmental pressure that Phragmope experiences in the intertidal zone. The new genus is taxonomically distant to the Northern Hemisphere genus Mesophyllum, and relates closer to taxa from the Southern Hemisphere, including Melyvonnea that occurs in South Africa and species of Mesophyllum sensu lato from Chatham-New Zealand-Australia, which collectively display a reduced fusion cell and lack of a pedestal in carposporangial conceptacles. Previous molecular studies based on SSU rDNA sequences and including an isolate of ‘M. engelhartii’ from South Africa support the same view. It is shown that the name ‘Fam.Mesophylleae Dum.’ Heeg [1891. Niederösterreiehische Lebermoose.- Verhandl. der k.k. zool.-botan. Gesellsch. in Wien 41:567–573] in Leverworts is invalid. Hence Mesophyllaceae Athanasiadis [2016. Phycologia Europaea Rhodophyta, Vols 1 & 2. Published by the author, Gothenburg. xlviii + 1504 pages] is available in the Corallinales (including Hapalidiales), while Mesophyllumaceae Schneider & Wynne (2019. Fourth addendum to the synoptic review of red algal genera. Botanica Marina. 62:355–367) becomes a later synonym.

摘要

芦苇差异（Lithothamnion差异）因几种活跃的生长方式而被公认为是南非特有的新单型属，包括顶端分生组织替代，多孔概念齿管中细胞条的产生以及在多孔概念齿上形成第二个紧凑，无孔的屋顶。分生组织的更换最多涉及三层。细胞条的发育始于由衬里细丝的基底细胞产生投射细胞，随后这些细胞聚结形成屏障。上皮下分裂产生第二个紧凑的屋顶，该屋顶由1-2个腹膜细胞和一层上皮细胞组成。假定这些新颖性反映了克服竞争和芦苇所带来的环境压力的进化进步潮间带的经验。该新属在分类学上与北半球的中叶目属较远，并与南半球的分类单元更近，包括南非的Melyvonnea和产自Chatham-New Zealand-Australia的Mesophyllum sensu lato的种，它们共同表现出减少的融合细胞，在软骨膜上没有基架。以前基于SSU rDNA序列的分子研究，其中包括' M. engelhartii '的分离物来自南非的支持者持相同观点。显示名称为“ Fam.Mesophylleae Dum”。Heeg [1891。NiederösterreiehischeLebermoose。-Verhandl。德尔·库克·波坦 格塞尔施。在Wien 41：567–573中]在Leverworts中无效。因此Mesophyllaclacaee Athanasiadis [2016。欧洲紫罗兰植物志，第1卷和第2卷。由作者哥德堡出版。xlviii + 1504页]可在Corallinales（包括Hapalidiales）中找到，而Mesophyllumaceae Schneider＆Wynne（2019年。《红藻属概要》第四期补编。BotanicaMarina。62：355–367）成为后来的同义词。