The small size (< 5 mm) of marine microfilamentous green algae makes it difficult to identify based on field collections, remaining largely unnoticed. To catalogue the diversity of these diminutive marine algae, a combination of culture-based taxonomic studies and DNA barcoding has proven to be a successful approach. During subtidal surveys in the northeastern Brazil, microfilamentous green algae were isolated as epiphytes on red algae cultured in laboratory. In this work, we used thallus ontogeny and plastid tufA gene sequences to elucidate the taxonomic identity of these isolates. Molecular and morphological evidence revealed that Brazilian specimens correspond to Ulvella endozoica, a poorly known species thought to be endemic to Florida, its type locality. Since U. endozoica was not found in gorgonian corals, as in the original description, this species does not follow a host specificity pattern, growing in more diverse substrata than previously thought. The origin of U. endozoica in Brazil remains undetermined, and we concluded that it is a cryptogenic species. Limited sampling, troublesome taxonomy, and difficulty in finding Ulvella species make them overlooked in Western Atlantic, resulting in taxonomic and biogeographic gaps. Our results expand southward the known distribution range of U. endozoica, demonstrating that an integrative barcode and laboratory culture-based approach is critical to uncover these inconspicuous algae.

海洋微丝状绿藻的尺寸很小（<5毫米），很难根据田间收集物进行鉴定，但在很大程度上并未引起注意。为了对这些小型海洋藻类的多样性进行分类，基于文化的分类学研究和DNA条形码的结合已被证明是一种成功的方法。在巴西东北部的潮下调查中，微丝状绿藻被分离为实验室培养的红藻的附生植物。在这项工作中，我们使用了all虫的个体发育和质体tuf A基因序列来阐明这些分离株的分类学身份。分子和形态学证据表明，巴西标本对应于内生Ulvella菌，这是一种鲜为人知的物种，被认为是佛罗里达特有的地方性物种。以来在原始珊瑚中未发现内生U.zoozoica，该物种未遵循宿主特异性模式，在比以前认为的更多样化的基质中生长。内生U.zoozoica在巴西的起源尚未确定，我们得出的结论是它是一种隐源物种。有限的采样，麻烦的分类学以及难以找到Ulvella的物种，使它们在西大西洋被忽视了，从而导致了分类学和生物地理学方面的差距。我们的结果向南扩展了已知的内生U.分布范围，表明整合条形码和基于实验室培养的方法对于发现这些不起眼的藻类至关重要。