Mukhim D Khlur Baiaineh, Sarma Kangkan, Choudhury Hrishikesh, Das Rajdeep, Chandran Rejani, Singh Rajeev K, Warbah Deisakee P, Lyngdoh Wandalin, Sarkar Uttam Kumar, Sarma Dandadhar
Department of Zoology, Lady Keane College, Shillong, India.
Department of Zoology, Gauhati University, Guwahati, India.
J Fish Biol. 2025 Sep;107(3):866-885. doi: 10.1111/jfb.70092. Epub 2025 May 23.
Integrative taxonomy reveals a new troglophilic species of Schistura, from a cave-dwelling population inhabiting stream draining (Barak-Surma-Meghna drainage) through the Krem (=cave) Mawjymbuin in East Khasi Hills of Meghalaya. Morphologically, the new species is easily distinguished from its congeners in having a combination of characters, including a unique colour pattern in the form of 14-20 greyish black to faint black bars overimposed to a black midlateral stripe on a greyish brown to pale beige (yellowish green in life); pre-dorsal bars thin, numerous, wider than interspaces, weakly contrasted, sometimes broken and/or incomplete; bars posterior of anal-fin base numerous and variable, mostly broken or incomplete, located on lower flank, weakly contrasted; a complete lateral line; presence of an axillary pelvic lobe; an uninterrupted thick black stripe along the base of the dorsal fin; an incomplete black basicaudal bar, dissociated, occupying median one-third of caudal-fin base; conspicuous black botch on the procurrent rays of the upper lobe of the caudal fin; and a type of sexual dimorphism: males with slender body, bars mostly irregular on flanks and slightly puffy cheek with greater lateral head length; females with regular-shaped bars and swollen body. Analysis of the mitochondrial cytochrome c oxidase I (COI) gene sequence of the new species shows significant genetic divergence with p distances ranging 4.5%-13.6% from its sister species found in northeast India, supporting its report as new species. Further, this finding is also validated by phylogenetic analysis and the species delimitation approaches, Assemble Species by Automatic Partitioning (ASAP) and Poisson Tree Processes (PTP), which clearly resolved that the Schistura densiclava sp. nov. is distinct from its sister species. Although the species has been sampled from the cave, it retains a fully pigmented body and functional eyes, which are not reduced when compared to other epigean Schistura, tentatively indicating it as a troglophile. Distribution of the new species is limited to the cave, which suggests an endemism in this cave system.
综合分类学揭示了一种新的隐穴丽脂鲤属物种，该物种来自一个洞穴栖息种群，它们生活在流经梅加拉亚邦东卡西丘陵的Krem（即洞穴）马金布因的溪流排水区域（巴拉克-苏尔马-梅格纳排水系统）。从形态上看，新物种很容易与其同属物种区分开来，它具有一系列特征组合，包括独特的颜色图案，即14至20条灰黑色至浅黑色条纹叠加在灰棕色至浅米色（活体为黄绿色）的黑色中侧条纹上；背鳍前的条纹细、多，比间隔宽，对比度弱，有时断裂和/或不完整；臀鳍基部后方的条纹多且变化大，大多断裂或不完整，位于体侧下部，对比度弱；有一条完整的侧线；有腋鳞叶；沿背鳍基部有一条不间断的粗黑色条纹；有一条不完整的黑色尾基部条纹，分离，占据尾鳍基部中间三分之一；尾鳍上叶的前向鳍条上有明显的黑色斑点；以及一种性二态性：雄性身体细长，体侧条纹大多不规则，脸颊稍肿，头部侧长较大；雌性条纹形状规则，身体肿胀。对新物种线粒体细胞色素c氧化酶I（COI）基因序列的分析表明，其与在印度东北部发现的姐妹物种的p距离在4.5%-13.6%之间，存在显著的遗传差异，支持将其报道为新物种。此外，系统发育分析以及物种界定方法——自动划分组装物种（ASAP）和泊松树过程（PTP）也验证了这一发现，它们清楚地表明新种致密丽脂鲤与它的姐妹物种不同。尽管该物种是从洞穴中采集的，但它保留了完全色素沉着的身体和功能性眼睛，与其他地表丽脂鲤相比并未退化，初步表明它是一种洞穴爱好者。新物种的分布仅限于该洞穴，这表明该洞穴系统存在特有物种。
