1 INTRODUCTION

Monitoring the fish community in September 2019 of the floodplain waters near Bislich at the Lower Rhine, an unknown, small Gobiid species was firstly caught that differed considerably from all other known alien Gobiids in our region. Based on morphological descriptions and keys provided by Kottelat and Freyhof (2007), it was most probable that the new species belonged to the genus Knipowitschia. This refers especially to morphological structures at the head (e.g. oculoscapular canals) as well as the scaling (e.g. on the caudal penduncle). Because the species is also spreading massively in the Rhine delta in the Netherlands (Stichting RAVON, 2020), colleagues from the Netherlands and Belgium initiated a first genetic survey proving that the species belongs to the Knipowitschia caucasica‐complex (Jelger Herder, RAVON, pers. comm., a paper on this topic is in preparation). We therefore decided to name the species as Knipowitschia cf. caucasica (Figure 1, for a detailed morphological description refer to Kottelat & Freyhof, 2007). Relevant literature on the distribution of Knipowitschia species in Europe (e.g. Didenko et al., 2020; Halasi‐Kovacs et al., 2011) offered the next closest distribution areas in the middle section of the Danube River Basin. This distribution with an extremely high distance between the southeastern distribution limit in the Danube basin and the northwestern areas of the Lower Rhine is quite similar to what is known from Neogobius fluviatilis (Roche et al., 2013) and clearly differs from more continuous distributions as described for Neogobius melanostomus and Ponticola kessleri (Adrian‐Kalchhauser et al., 2016; Borcherding et al., 2011). With the first catch of the Caucasian dwarf goby at the Lower Rhine, we now want to describe the distribution in this area, to add first data on the population structure and feeding in the new habitat, and to draw the attention to this new member of the fish community in western European countries.

中文翻译：

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高加索矮人虾虎鱼，一种新的外星人戈比科，分布在德国下莱茵

1引言

2019年9月，对下莱茵河Bislich附近洪泛区水域的鱼类群落进行了监测，首先发现了一种未知的小型戈壁鱼物种，该物种与我们地区所有其他已知外来戈壁鱼有很大不同。根据Kottelat和Freyhof（2007）提供的形态学描述和关键词，新物种最有可能属于Knipowitschia属。这尤其是指头部（例如，肩cap骨管）的形态结构以及鳞屑（例如，尾鳍上的形态）。因为该物种也在荷兰的莱茵河三角洲大规模传播（Stichting RAVON，  2020），来自荷兰和比利时的同事发起了首次基因调查，证明该物种属于Knipowitschia caucasica -complex（Jelger Herder，RAVON，pers。comm。，有关该主题的论文正在准备中）。因此，我们决定命名的物种Knipowitschia比照 高加索（图1，有关详细的形态学描述，请参见Kottelat＆Freyhof，  2007）。有关欧洲Knipowitschia物种分布的相关文献（例如，Didenko等，  2020； Halasi-Kovacs等，  2011））提供了多瑙河流域中段的下一个最近分布区域。这种分布在多瑙河盆地的东南分布极限与下莱茵河的西北地区之间有极高的距离，这与从Neugobius fluviatilis（Roche et al。，2013）所知非常相似， 并且显然与更连续的分布不同。描述了黑毛新骨蟹和蓬蒂科拉·凯斯莱（Pedicola kessleri）（Adrian-Kalchhauser等，2016 ; Borcherding等 ，  2011）。随着下莱茵河高加索矮人虾虎鱼的首次捕获，我们现在要描述该地区的分布，添加有关人口结构和新栖息地的觅食的第一批数据，并提请注意该新成员西欧国家的鱼类社区。