Clarifying confusion – <i>Prorocentrum triestinum</i> J.Schiller and <i>Prorocentrum redfieldii</i> Bursa (Prorocentrales, Dinophyceae) are two different species

The Prorocentrales are a unique group of dinophytes based on several apomorphic traits, but species delimitation is challenging within the group. <i>Prorocentrum triestinum</i> was described by Josef Schiller in 1918 as an important bloom-forming species from Trieste (Mediterranean, Adriatic Sea) with a conspicuous asymmetric outline and a small, asymmetrically located subapical spine. All subsequent records under this name fail to conform to Schiller’s original description. These inconsistencies have their origin in John Dodge’s 1975 revision of <i>Prorocentrum</i>, which placed <i>Prorocentrum redfieldii</i>, a more symmetrical, slender species with a long apical spine, into synonymy under <i>P. triestinum</i>. To clarify this confusion, we collected samples at the type locality of <i>P. triestinum</i> in Trieste and established a strain that is morphologically consistent with the protologue and suitable for use in epitypification. Morphology and rRNA sequence data of this strain were compared with four new strains identified as <i>P. redfieldii</i> from the Mediterranean Sea and the North Atlantic Ocean. Cells of <i>P. triestinum</i> had an asymmetric outline in lateral view and a small, dorso-subapical spine. These features, which are readily resolved by light microscopy, were distinct from those of the nearly symmetrical and slender cells of <i>P. redfieldii</i>, which had a long, apically located spine. The species are nevertheless closely related and share an identical architecture of the periflagellar area with a distinctive, largely reduced accessory pore together with a very small platelet 7. This apomorphy clearly differentiates both species from other species of <i>Prorocentrum</i>. Both species differ in their primary rRNA sequences, and ITS and LSU sequence differences will enable them to be distinguished in future meta-barcoding studies. The present study demonstrates that <i>P. triestinum</i> and <i>P. redfieldii</i> are distinct species and thus contributes to a reliable biodiversity assessment of <i>Prorocentrum</i>. HIGHLIGHTS <i>Prorocentrum triestinum</i> is characterised molecularly for the first time and delimited from <i>P. redfieldii</i>. The identity of important bloom-forming species is clarified. Structural details of the periflagellar area are described.原甲藻目（Prorocentrales）是一类具有多项衍征的独特甲藻类群，但该类群内的物种界定颇具挑战。1918年，约瑟夫·席勒（Josef Schiller）对的里雅斯特原甲藻（*Prorocentrum triestinum*）进行了描述，该物种是源自的里雅斯特（地中海亚得里亚海）的重要赤潮形成物种，具有醒目的不对称轮廓与小型、不对称分布的亚顶刺。 此后所有以该名称发表的记录均不符合席勒的原始描述。此类不一致可追溯至约翰·多奇（John Dodge）1975年对原甲藻属（*Prorocentrum*）的分类修订，该修订将雷德菲尔德原甲藻（*Prorocentrum redfieldii*）归为的里雅斯特原甲藻的异名，而雷德菲尔德原甲藻是一类更对称、体型修长且具长顶刺的物种。 为厘清这一分类混乱，我们在的里雅斯特原甲藻的模式产地的里雅斯特采集了样本，并构建了一株形态与原始模式文献一致、适用于新模式指定的菌株。将该菌株的形态学特征与核糖体RNA（rRNA）序列数据，与4株从地中海及北大西洋分离的、鉴定为雷德菲尔德原甲藻的新菌株进行了比对。 的里雅斯特原甲藻的细胞在侧视图中呈不对称轮廓，且具有小型的背亚顶刺。这些可通过光学显微镜清晰分辨的特征，与雷德菲尔德原甲藻的特征显著不同：后者细胞近乎对称、体型修长，且具长顶刺。尽管如此，两个物种亲缘关系密切，共享一套相同的鞭毛周区结构：具有独特且大幅简化的副孔，以及极小的第7板片。该衍征可将两个物种与其他原甲藻属物种明确区分开来。 两个物种的核心rRNA序列存在差异，内转录间隔区（ITS）与大亚基核糖体RNA（LSU）序列的差异也将为未来元条形码测序研究中区分二者提供依据。本研究证实的里雅斯特原甲藻与雷德菲尔德原甲藻为两个独立物种，从而为原甲藻属的可靠生物多样性评估提供了支撑。 研究亮点： 1. 首次对的里雅斯特原甲藻进行了分子特征描述，并将其与雷德菲尔德原甲藻进行了物种界定； 2. 厘清了重要赤潮形成物种的分类身份； 3. 描述了鞭毛周区的精细结构细节。

搜集汇总

背景与挑战

背景概述

该数据集是一个分类学研究，旨在澄清Prorocentrum triestinum和Prorocentrum redfieldii为两个不同的浮游植物物种，基于从地中海和北大西洋采集样本的形态学与分子生物学（如rRNA序列）证据分析。研究通过详细描述物种的形态差异（如不对称轮廓和刺的位置）和系统发育关系，解决了历史分类混淆，并支持可靠的生物多样性评估。