目的 了解速生薄口螨成螨扫描电镜下形态特征，并探讨该物种与粉螨中其他螨种之间的亲缘关系。方法 从纯培养的速生薄口螨中分离出成螨，使用扫描电子显微镜观察其外部形态。提取该螨的DNA，PCR扩增细胞色素氧化酶亚基1（cox1）基因和内转录间隔区（ITS）并测序，与GenBank上8种粉螨的ITS序列和cox1序列进行比对，采用最大似然法构建系统进化树。结果 扫描电镜下可见速生薄口螨的腹面表皮内突较发达，足Ⅰ表皮内突愈合成胸板，足Ⅱ表皮内突伸达中央，未连接；腹面有2对几丁质环，雄螨位于足Ⅱ~Ⅳ基节之间；雌螨前对几丁质环位于足Ⅱ~Ⅲ之间，后对几丁质环位于足Ⅳ基节水平；雄螨可见生殖褶、叶状瓣及阳茎等结构。PCR扩增和测序结果显示，cox1序列长539 bp，ITS基因片段序列长1 633 bp，与预期一致。ITS序列比对结果显示，速生薄口螨与热带无爪螨（GenBank登录号为KC215362）序列相似性最高为90.41%，与其他粉螨序列相似性为83.33%~89.73%。cox1序列比对结果显示，速生薄口螨与害嗜鳞螨（GenBank登录号为MT075728）序列相似性最高，为83.55%，与其他粉螨序列相似性为79.78%~82.12%。基于ITS和cox1序列构建的系统进化树在拓扑结构上存在差异：在cox1序列构建的系统进化树上，速生薄口螨为一单支，与其他8种粉螨不在同一进化支上，与形态学分类较为接近；在ITS序列构建的系统进化树上，速生薄口螨与罗宾根螨聚为一支，与形态学分类存在差异。结论 扫描电镜下可清晰观察到速生薄口螨雌雄成螨的形态结构。基于cox1序列分析结果显示速生薄口螨与其他粉螨的亲缘关系较远。

Objective To observe the morphological characteristics of adult Histiostoma feroniarum under the electron microscope, and to study the genetic relationship between this species and other mite species of Acaridae. Methods The adult stage of H. feroniarum was isolated from the culture, and its external morphological features were observed using scanning electron microscopy (SEM), followed by extracting the mite DNA, for amplifying the cytochrome oxidase subunit 1 (cox1) and internal transcribed spacer (ITS) by PCR. The ITS and cox1 gene was sequenced and compared with the other 8 Acaridae species in GenBank. The phylogenetic tree was constructed by the maximum likelihood method. Results Under the electron microscope, the ventral epidermal protrusions of the mites were more developed. The epidermal protrusions of foot I healed into the chest plate, and the epidermal protrusions of foot Ⅱ extended to the centre and were not connected. There were 2 pairs of chitinous rings on the ventral surface, and the male adults were located between the Ⅱ-Ⅳ basal ganglia. The first pair of chitin rings of the female mite was located between the foot Ⅱ and Ⅲ, and the last pair of chitin rings were located at the level of the foot Ⅳ basal ganglia. Compared with the light microscope, the structures of male reproductive folds, leaflets and penis were clearer under the electron microscope. The cox1 and ITS sequences were obtained by PCR amplification, which was 539 bp and 1 633 bp. The ITS sequence similarity comparison results showed that the sequence similarity between H. feroniarum and Blomia tropicalis (GenBank accession no. KC215362) was the highest, which was at 90.41%, and the sequence similarity with other Acaridae species was 83.33%-89.73%. The cox1 sequence alignment showed that the highest sequence similarity was 83.55% between H. feroniarum and Lepidoglyphus destructor (GenBank accession no. MT075728), and the sequence similarity with other Acaridae species ranged from 79.78%-82.12%. The phylogenetic tree constructed based on ITS and cox1 sequences has differences in topological structure. showing that H. feroniarum is a single branch, but not at the same branch of other Acaridae species, which is likely consistent with morphological classification. The phylogenetic analysis based on ITS showed that H. feroniarum and Rhizoglyphus robini were clustered as a branch, which differs from morphological classification. Conclusion The morphological structure of male and female H. feroniarum could be clearly observed by scanning electron microscopy. Phylogenetic analysis of cox1 sequence reveals relatively distant genetic relationship seen between the H. feroniarum and other acaroid mites.