A morphologically unique species of Ptinidae (Coleoptera) and the first found in mid-Cretaceous Kachin amber (Myanmar)

Some groups of fossil beetles are difficult to study because the characters needed for identification or classification are hidden and difficult to study. Ptinidae is one of these groups. We describe herein <i>Cretasernus spinosus</i> gen. et sp. nov. (Coleoptera: Ptinidae) based on one fossil specimen, the only known specimen of this family from Kachin amber (mid-Cretaceous of Myanmar). The holotype was imaged using an X-ray micro-CT system to obtain high-quality 3D images to complement the structures visualized using optical microscopes. The new species shows two autapomorphic characters never described in any extant or extinct species in this family: a groove near the base of the 11th antennomere, which makes it appear as a much smaller additional antennomere, and transverse metacoxae touching at the middle. Phylogenetic analysis of the new species clearly supports this new genus as part of Anobiidae <i>sensu stricto</i> (i.e. excluding the spider beetles) despite antennae that are certainly more similar to those seen in the many of the spider beetles (except for the modified 11th antennomere). Some of the extant species in this family are wood-borers and the involvement of beetles in resin production during the Cretaceous is a hypothesis that is suggested often. However, some ideas against the involvement of Ptinidae in resin production within the mid-Cretaceous forests of Myanmar are discussed. http://zoobank.org/urn:lsid:zoobank.org:pub:02CE8BF8-FC0C-4E39-8B75-FA70F2CBE2BB

部分化石甲虫类群的研究难度较高，原因在于其物种鉴定与分类所需的形态特征往往隐蔽且难以观测。蛛甲科（Ptinidae）正是这类类群之一。本文基于一件化石标本——该科在缅甸中白垩世克钦琥珀中目前已知的唯一标本，记述鞘翅目（Coleoptera）蛛甲科的一新属新种：刺棘白垩蛛甲（Cretasernus spinosus gen. et sp. nov.）。本研究通过X射线显微CT（X-ray micro-CT）系统对正模标本进行成像，以获取高质量三维图像，辅助光学显微镜下的结构观测。该新种具备两项蛛甲科现生及灭绝类群中均未被记载过的独有衍征：其一为第11触角节基部附近具一凹槽，使其外观如同额外多出的一个小型触角节；其二为后足基节呈横宽形，且在中部相互接触。尽管该新属的触角形态与多数蛛甲（仅第11触角节特化除外）更为相似，但针对该新种的系统发育分析明确支持其隶属于狭义窃蠹科（Anobiidae sensu stricto，即排除蛛甲类群）。该科部分现生类群为蛀木昆虫，而白垩纪时期甲虫参与树脂形成的假说也常被提出。不过本文也探讨了若干反对蛛甲科参与缅甸中白垩世森林树脂形成的观点。http://zoobank.org/urn:lsid:zoobank.org:pub:02CE8BF8-FC0C-4E39-8B75-FA70F2CBE2BB