Suárez-Morales Eduardo, Gutiérrez-Aguirre Martha A, Cervantes-Martínez Adrián, Iliffe Thomas M
El Colegio de la Frontera Sur (ECOSUR)-Chetumal, A.P. 424. Chetumal, Quintana Roo 77014, Mexico.
Universidad de Quintana Roo Campus Cozumel. Cozumel, Quintana Roo Mexico.
Zookeys. 2017 Apr 26(671):1-17. doi: 10.3897/zookeys.671.12052. eCollection 2017.
Surveys of the anchialine crustacean fauna of the Yucatan Peninsula (YP), Mexico, have revealed the occurrence of calanoid copepods. The genus Scott, 1892, belonging to the family Stephidae is among the most frequent and widely distributed groups in anchialine caves but has not been hitherto recorded from the YP. Recent collections from an anchialine cave in an island off the northern coast of the YP yielded many specimens of a new species of . The new taxon, , is described here based on male and female specimens. The new species is clearly distinguished from its congeners by the following characters: male left fifth leg with three terminal lamellae plus subdistal process, right leg with distal row of peg-like elements; female fifth leg with single long, acute apical process; genital double-somite with two rows each of 4 long spinules adjacent to operculum; legs 2-4 with articulated setae. The diversity of the genus shows regional differences; the Australia-Western Pacific region is the most diverse (eleven species), followed by the Mediterranean (seven species) and the Northeastern Atlantic (six species); only four species are known from the Northwestern Tropical Atlantic (NWTA). The morphology of the female fifth leg was examined to explore possible biogeographic trends in the genus; patterns suggest multiple colonization events in the highly diverse regions and a relatively recent radiation in the NWTA, characterized by anchialine forms. The introduction of stephid copepods in the region may be a relatively recent event derived from colonization of benthopelagic ancestral forms and subsequent invasion onto cave habitats. The new species appears to be linked to the strictly anchialine .
对墨西哥尤卡坦半岛（YP）沿岸洞穴甲壳动物区系的调查发现了哲水蚤的存在。1892年的斯科特属，属于斯蒂芬科，是沿岸洞穴中最常见且分布最广的类群之一，但此前在YP地区尚未有记录。最近从YP北海岸一个岛屿的沿岸洞穴采集到了许多该属新物种的标本。这里基于雄性和雌性标本描述了这个新分类单元。新物种通过以下特征与同属其他物种明显区分：雄性左第五胸足有三个末端薄片加亚远端突起，右胸足有远端一排钉状结构；雌性第五胸足有单个长而尖的顶端突起；生殖双节有两排，每排4根长刺，靠近鳃盖；第二至四对胸足有分节刚毛。该属的多样性存在区域差异；澳大利亚 - 西太平洋地区最为多样（11种），其次是地中海（7种）和东北大西洋（6种）；西北热带大西洋（NWTA）仅知有4种。对雌性第五胸足的形态进行了研究，以探索该属可能的生物地理趋势；模式表明在高度多样的地区有多次定殖事件，而NWTA有相对较新的辐射，以沿岸洞穴形态为特征。该地区斯蒂芬科哲水蚤的引入可能是一个相对较新的事件，源自底栖浮游祖先形态的定殖以及随后向洞穴栖息地的入侵。新物种似乎与严格的沿岸洞穴环境有关。
