A new species, Pseudacanthus alani n. sp., is described from cloud forest in Oaxaca, Mexico. This species is similar to Pseudacanthus junctistriatus Kuwert 1891 in size, shape of antennal lamella, and the absence of pubescence on abdominal terga, but has larger internal tubercles, an apex of central tubercle that is not free, glabrous elytral humerus, pubescent mesepisternum and mesepimeron and mesosternal scar, and male sexual characters. Photographs are provided of the head, male and female genitalia, and plectrum. Additionally, a taxonomic key to species of Pseudacanthus Kaup 1869 is provided, complemented with photographs of diagnostic characters. Finally, we propose two junior synonyms: Pseudacanthus solidus (Arrow 1907) n. syn. of Pseudacanthus junctistriatus and Pseudacanthus truquii Kuwert 1891 n. syn. of Pseudacanthus mexicanus (Truqui 1857).

一个新物种，Pseudacanthus alani n。sp. ，描述于墨西哥瓦哈卡的云雾森林。本种与Pseudacanthus junctistriatus Kuwert 1891 的大小、触角薄片的形状和腹部 terga 上没有短柔毛相似，但具有较大的内部结节、中央结节的顶端不游离、无毛的鞘翅、短柔毛的中下节和中节段和胸骨间疤痕，和男性性特征。提供了头部、男性和女性生殖器以及拨片的照片。此外，还提供了Pseudacanthus Kaup 1869物种的分类学关键，并附有诊断特征的照片。最后，我们提出了两个初级同义词：Pseudacanthus solidus(箭头 1907) n. 同义词 的Pseudacanthus junctistriatus和Pseudacanthus truquii Kuwert 1891年ñ。同义词 的Pseudacanthus mexicanus（Truqui 1857）。