Tran Ngoc-Son1, Dam Minh Anh1, Trinh-Dang Mau1, Pham Thi Phuong1, Brancelj A.2 2026. A new hyporheic species of Phyllognathopus Mrázek, 1893 (Crustacea: Copepoda: Harpacticoida: Phyllognathopodidae) from central Vietnam // Arthropoda Selecta. Vol.35. No.1: 32–40 [in English].
1 The University of Da Nang - University of Science and Education, 459 Ton Duc Thang St., Da Nang City 550000, Vietnam.
2 National Institute of Biology, Ljubljana, Večna pot 121, 1000 Ljubljana, Slovenia.
Ngoc-Son Tran: tnson@ued.udn.vn; https://orcid.org/0000-0003-2387-5822
doi: 10.15298/arthsel.35.1.05
ABSTRACT. An undescribed species of the genus Phyllognathopus Mrázek, 1893 was discovered during a survey of harpacticoid copepods from the hyporheic zone of the Suoi Da Stream and Cu De River in central Vietnam. The new species, Phyllognathopus danangensis sp.n., is morphologically similar to P. viguieri (Maupas, 1892), but can be distinguished from former one by: i) the absence of a proximal surface seta on the coxa of the maxillule; ii) the long pinnate posterolateral caudal seta (III); iii) the non-transformed inner terminal caudal seta (V); iv) the subapical insertion of the outermost seta on the exopod of P5 of the female. It also differs from other congeners, such as P. paludosus, P. volcanicus, P. paracamptoides, and P. vietnamensis, by a smooth anal operculum, three-segmented exopod of P4, and equal length of exopodal lobe and baseoendopod of P5.
KEY WORDS: hyporheic zone, Southeast Asia, stygobites, Phyllognathopodidae, taxonomy, Vietnam.