A comparative morphometric analysis of otoliths was done to understand the major morphometric characters responsible for differentiating two species of Green-eyes (Chlorophthalmus corniger and C. acutifrons) which is one of the dominant fish groups caught in the deep-sea trawling during the exploratory surveys as well as in the by-catch of trawlers targeting deep-sea shrimps at a depth range of 300 – 500 m in the Indian waters. A total of 53 intact, right otoliths (25 and 28 for C. corniger and C. acutifrons, respectively) were considered for the morphometric analysis to differentiate species collected from Andaman Sea. The study extracted four otolith morphometric measurements and five shape indices measured from the otoliths using image analysing software including otolith weight. The otolith morphometric parameters and shape indices showed significant relationship with the fish size were scaled with standard length to remove the influence of fish size from the data. Principal component analysis using scaled otolith morphometric measurements indicated that the first two axes described 84.78 % and 11.80 % of variation, respectively. The PC1 differentiated the species based on ellipticity and otolith weight followed by area and perimeter. C. acutifrons is differentiated from their congener with a more elliptic, heavy otolith with more otolith surface area. One-way PERMANOVA confirmed significant difference in otolith morphology between the species. Present study confirmed the suitability of otolith morphometric analysis in differentiating Chlorophthalmus species which are quite inevitable for taxonomic studies as well as for the better understanding of the species resolution in diet studies.

中文翻译：

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基于耳石形态测定法区分两种 Chlorophthalmus Corniger (Alcock, 1894) 和 C. acutifrons (Hiyama, 1940)

对耳石进行了比较形态计量分析，以了解负责区分两种绿眼（Chlorophthalmus corniger 和 C. acutifrons）的主要形态计量特征，绿眼是探索性调查期间在深海拖网捕捞中捕获的主要鱼类群之一以及在印度水域以 300 – 500 m 深度范围捕捞深海虾的拖网渔船的副渔获物。总共考虑了 53 个完整的右侧耳石（分别为 C.corniger 和 C.acutifrons 的 25 和 28 个）用于形态计量分析，以区分从安达曼海收集的物种。该研究使用包括耳石重量在内的图像分析软件从耳石中提取了四个耳石形态测量值和五个形状指数。耳石形态测量参数和形状指数显示出与鱼大小的显着关系，以标准长度进行缩放，以从数据中消除鱼大小的影响。使用缩放耳石形态测量测量的主成分分析表明，前两个轴分别描述了 84.78% 和 11.80% 的变化。PC1 根据椭圆度和耳石重量区分物种，然后是面积和周长。C. acutifrons 与它们的同类物不同，它具有更椭圆、更重的耳石和更多的耳石表面积。单向 PERMANOVA 证实了物种之间耳石形态的显着差异。