Two new species of <i>Hemidactylus</i> Goldfuss, 1820 (Squamata: Gekkonidae) from the coastal areas of northern Somaliland

The taxonomy of many <i>Hemidactylus</i> geckos from the Horn of Africa has recently been evaluated. However, the lack of fresh material for some species and also regions has led to the misidentification of some taxa and an underestimation of the true diversity in others. In this study we analyse new material of <i>Hemidactylus</i> collected from poorly known coastal areas of northern Somaliland. Our results support the existence of two yet undescribed species within the arid clade. One of the new species is small-sized and closely related to <i>H. afarensis</i> from the Afar Triangle in Ethiopia, and together with two other species (<i>H. foudaii, H. sinaitus</i>) forms the monophyletic group for which we propose here the name <i>sinaitus</i> species group. The other new species is medium to large-sized, known from only one locality, and belongs to the <i>macropholis</i> species group, where it is a sister species of <i>H. macropholis</i>. Both new endemic species from the northern coastal hyper-arid plains highlight the role of northern Somaliland as an important biodiversity hotspot. Furthermore, our results show pronounced genetic diversity within <i>H. macropholis</i>, and imply possible existence of cryptic taxa within the species. <i>Hemidactylus arnoldi</i> and <i>H. tropidolepis</i> have, for the first time, been sequenced and placed in a phylogenetic context in this study. Our results confirm that <i>H. tropidolepis</i> is nested within the African radiation and is most closely related to <i>H. funaiolii. Hemidactylus arnoldi</i> clustered within the Arabian radiation of <i>Hemidactylus</i> and it was recovered as a sister lineage to all other species of the radiation.近期学界对非洲之角地区的诸多半叶趾虎属（Hemidactylus）壁虎的分类学进行了重新评估。然而，部分物种及区域缺乏新鲜标本，导致部分类群被错误鉴定，同时低估了其他类群的真实物种多样性。本研究对从索马里兰北部鲜为人知的沿海区域采集的半叶趾虎属新标本展开分析。研究结果支持在干旱演化支中存在两个尚未被描述的新物种。其中一种新物种体型小巧，与埃塞俄比亚阿法尔三角区的阿法尔半叶趾虎（H. afarensis）亲缘关系密切，该物种与另外两个物种（H. foudaii、H. sinaitus）共同构成一单系群，我们在此将该类群命名为sinaitus物种组。另一种新物种体型中等至大型，目前仅知单一分布点，隶属于macropholis物种组，且为大鳞半叶趾虎（H. macropholis）的姐妹物种。这两种来自索马里兰北部沿海超干旱平原的特有新物种，进一步凸显了索马里兰北部作为重要生物多样性热点地区的地位。此外，本研究发现大鳞半叶趾虎（H. macropholis）内部存在显著的遗传多样性，暗示该物种内可能存在隐存类群。本研究首次对阿诺德半叶趾虎（H. arnoldi）与棱鳞半叶趾虎（H. tropidolepis）进行测序，并将其置于系统发育框架中开展分析。研究结果证实棱鳞半叶趾虎隶属于非洲辐射演化支，与富纳奥里半叶趾虎（H. funaiolii）亲缘关系最近；阿诺德半叶趾虎则聚类于半叶趾虎属的阿拉伯辐射演化支中，且被恢复为该辐射支所有其他物种的姐妹演化支。