Although many deep-sea species are considered to have transoceanic distribution, this assumption has rarely been critically tested. Using Hesiolyra (Hesionidae) as a case study, we show that careful molecular and morphological analyses are required for refuting/accepting claims about such wide distribution. Hesiolyra is a genus of polychaetes commonly found in hydrothermal vents of the Eastern Pacific, Atlantic and Indian Ocean. Nevertheless, H. bergi Blake, 1985, a species originally described from the Eastern Pacific Rise (EPR), is the only recognized species in this genus. Phylogenetic analyses based on the COI and 16 S rRNA genes revealed two monophyletic clades that were distinct from a clade consisting of H. bergi sequences. We erected two new species of Hesiolyra, herein named as H. longqiensis n. sp. from the Southwest Indian Ridge (SWIR) and H. heteropoda n. sp. from the Central Indian Ridge (CIR) and the Carlsberg Ridge (CR). Among them, H. longqiensis n. sp. is more closely related to H. bergi than to H. heteropoda n. sp. . Morphologically, the two newly described species can be easily distinguished from H. bergi. The notopodia and neuropodia of H. bergi and H. longqiensis n. sp., are of similar sizes, but the morphology of their lyrate chaetae and their dorsal cirri alternation patterns are different. In H. heteropoda n. sp., the notopodia are remarkably slimmer than the neuropodia, and it lacks lyrate chaetae. Overall, in this report two new species of Hesiolyra from the Indian Ocean ridges and show that the distribution of H. bergi is restricted to the Eastern Pacific Rise. Future exploration of other mid-ocean ridges is required to discover the true diversity of this genus of polychaetes inhabiting hydrothermal vent fields.

尽管许多深海物种被认为具有跨洋分布，但这一假设很少经过严格检验。使用Hesiolyra（Hesionidae）作为案例研究，我们表明，需要仔细的分子和形态分析才能驳斥/接受有关如此广泛的分布的主张。Hesiolyra是多毛类的一个属，通常在东太平洋，大西洋和印度洋的热液喷口中发现。尽管如此，最早从东太平洋上升区（EPR）描述的1985年的H. bergi Blake是该属中唯一被认可的物种。基于COI和16 S rRNA基因的系统发育分析揭示了两个单系进化枝，不同于由H. bergi组成的进化枝序列。我们竖立了两个新属的Hesiolyra，命名为H. longqiensis n。sp。来自西南印第安岭（SWIR）和H. heteropoda n。sp。来自中印度洋脊（CIR）和嘉士伯脊（CR）。其中，H。longqiensis n.。sp。与伯氏嗜血杆菌的亲缘关系比与异交 嗜血杆菌的亲缘关系更紧密。sp。。在形态上，可以容易地将两个新描述的物种与H. bergi区分开。该notopodia和neuropodia H. BERGI和H. longqiensis ñ。sp。的大小相似，但它们的裂解物壳状触角和背侧交替的形态不同。在H. heteropoda中 。sp。，Notopodia明显比Neuropodia更苗条，并且缺少裂解物褐变。总体而言，在本报告中，印度洋洋脊上有两个新的Hesiolyra物种，表明bergi的分布仅限于东太平洋上升。需要进一步探索其他中洋海脊，以发现居住在热液喷口领域的多毛cha属的真正多样性。