A new snailfish, Elassodiscus nyctereutes , previously confused with Elassodiscus caudatus , is described on the basis of genetic evidence and morphometric and meristic analysis of 55 specimens. The new species is most similar to E. caudatus in having a greatly reduced pelvic disk, two suprabranchial pores, trilobed teeth, and long pectoral-fin rays in the lower lobe that reach to the anal-fin origin. However, the new species is clearly distinguished from the latter by having more vertebrae (67–75 vs. 56–60), dorsal- (59–69 vs. 51–54), and anal-fin rays (52–63 vs. 45–50). The two species are parapatrically distributed in the North Pacific: E. nyctereutes is widely known from the southern part of the Sea of Okhotsk, off Rausu, eastern Hokkaido, Japan; the Pacific Ocean off Kamchatka and the Kuril Islands; the Aleutian Islands; and the Bering Sea at depths of 362–1,200 m; whereas E. caudatus is only known from the eastern North Pacific, from the eastern Gulf of Alaska to California at depths of 335–925 m. We also provide an emended diagnosis of the genus Elassodiscus , as well as a key to the known species.

中文翻译：

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来自北太平洋的 Elassodiscus (Cottoidei: Liparidae) 新种，对该属进行了修正

一种新的蜗牛鱼，Elassodiscus nyctereutes，以前与 Elassodiscus caudatus 混淆，根据遗传证据以及对 55 个标本的形态测量和分生分析进行描述。这个新物种与 E. caudatus 最相似，有一个大大缩小的骨盆盘、两个鳃上孔、三叶齿和下叶的长胸鳍鳍条，一直延伸到臀鳍起点。然而，新物种与后者的区别在于具有更多的椎骨（67-75 对 56-60）、背鳍（59-69 对 51-54）和臀鳍鳍条（52-63 对45-50）。这两个物种在北太平洋准地区分布： E. nyctereutes 在鄂霍次克海南部、日本北海道东部罗臼附近广为人知；堪察加半岛和千岛群岛附近的太平洋；阿留申群岛；和 362–1,200 m 深处的白令海；而 E. caudatus 仅在北太平洋东部，从阿拉斯加东部湾到加利福尼亚的 335-925 m 深处被发现。我们还提供了 Elassodiscus 属的修正诊断，以及已知物种的关键。