Auchenionchus crinitus and Auchenionchus microcirrhis share their distributional area along the Chilean coast. These labrisomid blennies are difficult to recognize based on the attributes described in taxonomic keys, which consist of overlapped or non-informative morphological and meristic characteristics of body parts. Sagittae otolith shape is useful for species determination; thus, the aim of our study was to evaluate the discriminant power of sagittae otoliths through analyses of shape indices and geometric morphometrics, and to describe the sagittae otolith shape of the two fish species. Four linear measurements (length, width, area and perimeter) of sagittae otoliths were considered to calculate the shape indices. Inter-specific differences were assessed by Mann-Whitney U tests for each index, and no significant differences between species were found (U = 181.5–256; p > 0.05). Based on these results, the shape indices evaluated here must not be employed for species of the genus Auchenionchus. A total of 72 landmarks contouring sagittae otoliths were considered for the geometric morphometric analysis, where the least-squares Procrustes method was followed to obtain a consensus coordinate matrix. The sagittae otolith was morphologically distinctive for each species, A. crinitus shows a wide and curved rostrum compared with A. microcirrhis, where this feature is more angled and elongated. Similarly, the posterior edge in the otolith of A. crinitus is wide in curvature, while this portion is angled in curvature in A. microcirrhis. The vertex between rostrum and anti-rostrum forms a cordiform shape in the sagittae otolith of both species, although in A. crinitus this characteristic is more prominent. A Principal Component Analysis and a Discriminant Function Analysis using the consensus coordinate matrix allowed us to confirm the differences between species according to sagittae otolith shape. Our study constitutes the first assessment of sagittae otolith shape via geometric morphometrics in the family Labrisomidae.

Auchenionchus crinitus和Auchenionchus microcirrhis沿智利海岸共享它们的分布区。根据分类学关键字中描述的属性，这些labrisomid blennies 很难识别，这些属性由身体部位的重叠或非信息形态和分生特征组成。Sagittae 耳石形状可用于物种确定；因此，我们研究的目的是通过分析形状指数和几何形态测量学来评估矢状面耳石的判别能力，并描述两种鱼类的矢状面耳石形状。考虑了矢状耳石的四个线性测量值（长度、宽度、面积和周长）来计算形状指数。Mann-Whitney U评估了种间差异对每个指数进行检验，没有发现物种之间存在显着差异（U = 181.5-256；p  > 0.05）。根据这些结果，此处评估的形状指数不得用于Auchenionchus属的物种。总共 72 个地标轮廓矢状耳石被考虑用于几何形态测量分析，其中遵循最小二乘 Procrustes 方法以获得一致坐标矩阵。每个物种的矢状耳石在形态上都是独特的，与A. microcirrhis相比，A . crinitus显示出一个宽阔弯曲的喙部，其中该特征更具角度和拉长。类似地，A. crinitus耳石的后缘曲率宽，而这部分在A. microcirrhis中曲率成角度。在两个物种的矢状耳石中，讲台和反讲台之间的顶点形成心形形状，尽管在A. crinitus 中这种特征更为突出。使用一致坐标矩阵的主成分分析和判别函数分析使我们能够根据矢状面耳石形状确认物种之间的差异。我们的研究构成了通过几何形态测量学对唇形科动物耳石形状的首次评估。