Lost before found: A new species of whaler shark Carcharhinus obsolerus from the Western Central Pacific known only from historic records

Carcharhinus obsolerus is described based on three specimens from Borneo, Thailand and Vietnam in the Western Central Pacific. It belongs to the porosus subgroup which is characterised by having the second dorsal-fin insertion opposite the anal-fin midbase. It most closely resembles C. borneensis but differs in tooth morphology and counts and a number of morphological characters, including lack of enlarged hyomandibular pores which are diagnostic of C. borneensis. The historic range of C. obsolerus sp. nov. is under intense fishing pressure and this species has not been recorded anywhere in over 80 years. There is an urgent need to assess its extinction risk status for the IUCN Red List of Threatened Species. With so few known records, there is a possibility that Carcharhinus obsolerus sp. nov. has been lost from the marine environment before any understanding could be gained of its full historic distribution, biology, ecosystem role, and importance in local fisheries.绝灭真鲨（Carcharhinus obsolerus）基于采自中西太平洋婆罗洲、泰国及越南的3份标本被正式命名描述。该种隶属于porosus亚组，该亚组的典型鉴别特征为第二背鳍起点与臀鳍基部中点相对。该物种与宽纹真鲨（C. borneensis）形态相似度最高，但在齿形、齿数及多项形态特征上存在明显差异，例如不具备宽纹真鲨的标志性膨大舌颌孔。绝灭真鲨（Carcharhinus obsolerus sp. nov.）的历史分布区域正承受高强度捕捞压力，且已有80余年未在任何海域被采集记录到。当前亟需对其开展世界自然保护联盟（IUCN）濒危物种红色名录的灭绝风险等级评估。鉴于已知记录极少，该新种有可能在人类尚未完全探明其完整历史分布范围、生物学特性、生态系统功能以及其在地方渔业中的重要性之前，就已从海洋环境中永久消失。