Porolithon is one of the most ecologically important genera of tropical and subtropical crustose (non-geniculate) coralline algae growing abundantly along the shallow margins of coral reefs and functioning to cement reef frameworks. Thalli of branched, fruticose Porolithon specimens from the Indo-Pacific Ocean traditionally have been called P. gardineri, while massive, columnar forms have been called P. craspedium. Sequence comparisons of the rbcL gene both from type specimens of P. gardineri and P. craspedium and from field-collected specimens demonstrate that neither species is present in east Australia and instead resolve into four unique genetic lineages. Porolithon howensis sp. nov. forms columnar protuberances and loosely attached margins and occurs predominantly at Lord Howe Island; P. lobulatum sp. nov. has fruticose to clavate forms and free margins that are lobed and occurs in the Coral Sea and on the Great Barrier Reef (GBR); P. parvulum sp. nov. has short (<2 cm), unbranched protuberances and attached margins and is restricted to the central and southern GBR; and P. pinnaculum sp. nov. has a mountain-like, columnar morphology and occurs on oceanic Coral Sea reefs. A rbcL gene sequence of the isotype of P. castellum demonstrates it is a different species from other columnar species. In addition to the diagnostic rbcL and psbA marker sequences, the four new species may be distinguished by a combination of features including thallus growth form, margin shape (attached or unattached), and medullary system (coaxial or plumose). Porolithon species, because of their ecological importance and sensitivity to ocean acidification, need urgent documentation of their taxonomic diversity.

中文翻译：

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来自大堡礁、珊瑚海和豪勋爵岛的新分枝孔石物种（珊瑚目、红藻门）

Porolithon是生态上最重要的热带和亚热带壳状（非膝状）珊瑚藻属之一，沿着珊瑚礁的浅缘大量生长，并起到巩固珊瑚礁框架的作用。来自印度-太平洋的分枝、多果的Porolithon标本的菌体传统上被称为P. gardineri，而块状、柱状的形式被称为P. craspedium。对P. gardineri和P. craspedium模式标本以及野外采集标本的rbc L 基因进行的序列比较表明，这两个物种都不存在于澳大利亚东部，而是分解为四个独特的遗传谱系。Porolithon howensis sp. 十一月 形成柱状突起和松散的边缘，主要出现在豪勋爵岛；分叶 P. lobulatum sp. 十一月 具有果状棒状形状和裂片状游离边缘，出现在珊瑚海和大堡礁 (GBR) 上；P. parvulum sp. 十一月 有短（<2厘米）、不分枝的突起和附着的边缘，仅限于大堡礁中部和南部；和P. pinnaculum sp。十一月 具有山状柱状形态，出现在海洋珊瑚海礁石上。P.castellum同种型的 rbc L 基因序列表明它是与其他柱状物种不同的物种。除了诊断性rbc L 和psb A 标记序列外，这四个新物种还可以通过叶状体生长形式、边缘形状（附着或不附着）和髓质系统（同轴或羽状）等特征的组合来区分。孔石物种由于其生态重要性和对海洋酸化的敏感性，需要紧急记录其分类多样性。