Department of Ichthyology, American Museum of Natural History, New York, New York, USA.
Laboratory of Systematics and Evolution of Teleost Fishes, Institute of Biology, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil.
J Fish Biol. 2022 Jan;100(1):161-174. doi: 10.1111/jfb.14930. Epub 2021 Nov 22.
This study resolves a significant impediment to the taxonomy of the Neotropical endemic hematophagous candirus by providing the first high-resolution, CT-based osteological descriptions of type and nontype specimens of Paracanthopoma parva, type species of the genus. We also describe the distinctive new species Paravandellia alleynei based on specimens that were previously misidentified as Parac. parva in the only taxonomic study of that species since its 1935 description. Paracanthopoma parva is distinguished from all nominal congeners by its parietosupraoccipital and caudal skeleton morphology and by various meristics, including numbers of teeth on median premaxilla, vertebrae, and procurrent and principal caudal-fin rays. Paravandellia alleynei differs from both nominal congeners (Paravandellia oxyptera and Paravandellia phaneronema) by the unique morphology of its maxilla, mesethmoid and opercular apparatus, relative position of the pelvic- and anal-fin origins, orientation of the opercular odontodes, and various meristics, including numbers of vertebrae, median premaxillary teeth, medial teeth on premaxilla, branchiostegal rays, opercular and interopercular odontodes, distal claw-like premaxillary teeth, dorsal-fin rays and dentary teeth. This is the first species of Paravandellia recognized from Guyana and the Essequibo River basin. It is currently known only from two type specimens from the lower Essequibo River basin and 43 nontype specimens from the upper Branco River basin. By providing the first skeletal observations for type specimens of the type species Parac. parva and for topotypic specimens of all three nominal species of Paravandellia, we clarify and confirm the diagnosis of Parac. parva and establish a robust foundation for ongoing taxonomic revisions of these two small-sized and species-poor, yet trans-continentally distributed genera, both of which contain considerable unrecognized diversity.
这项研究解决了一个重要的障碍，即新热带地区特有吸血性坎迪鲁斯的分类学问题，为 Paracanthopoma parva （该属的模式种）的模式和非模式标本提供了首次基于高分辨率 CT 的骨骼描述。我们还根据以前在对该物种的唯一分类学研究中被错误鉴定为 Parac. parva 的标本描述了独特的新物种 Paravandellia alleynei。Paracanthopoma parva 与所有命名的近缘种不同，其顶骨和尾骨骨骼形态以及各种数量特征，包括中前颌骨、脊椎和前导和主尾鳍射线的牙齿数量。Paravandellia alleynei 与两个命名的近缘种（Paravandellia oxyptera 和 Paravandellia phaneronema）不同，其上颌骨、中筛骨和鳃盖器官的形态独特，骨盆和肛门鳍起源的相对位置，鳃盖齿的方向，以及各种数量特征，包括脊椎数量、中前颌骨牙齿、前颌骨上的内侧牙齿、鳃盖骨和间鳃盖骨齿、前上颌骨远端爪状牙齿、背鳍射线和齿骨牙齿。这是从圭亚那和埃塞奎博河流域识别出的第一个 Paravandellia 物种。目前仅从埃塞奎博河流域下游的两个模式标本和上布兰科河流域的 43 个非模式标本中得知。通过提供模式种 Parac. parva 的模式标本和所有三个命名的 Paravandellia 物种的代表标本的首次骨骼观察结果，我们澄清并确认了 Parac. parva 的诊断，并为这两个小型和物种较少但跨大陆分布的属的持续分类修订奠定了坚实的基础，这两个属都包含了大量未被识别的多样性。
