 |
| ‘Henicorhynchus’ thaitui Nguyen, Ho, Hoang, Wu & Zhang, 2020 |
Abstract
‘Henicorhynchus’ thaitui sp. nov. is described from a subterranean stream in a karst cave in Phong Nha Ke Bang National Park, Quang Binh Province, Central Vietnam. It differs from all congeners in having a pale pink body in life, smaller eyes with diameter less than the maxillary barbel length, and two pairs of barbels, the maxillary barbel being much longer than the rostral barbel.
Keywords: Cypriniformes, karst system, morphology, Southeast Asia, taxonomy
 |
| Lateral view of ‘Henicorhynchus’ thaitui sp. nov.: a IEBR 105901, holotype, 74.3 mm SL; and b IHB 2016105898, paratype, 98.0 mm SL. Both specimens caught in central Vietnam: Son River system in Gianh river drainage: Khe Lanh Cave. |
 |
| ‘Henicorhynchus’ thaitui sp. nov., specimen not preserved, about 100 mm SL, Vietnam: Khe Lanh cave; life coloration. |
 |
‘Henicorhynchus’ thaitui sp. nov.
Diagnosis: ‘Henicorhynchus’ thaitui sp. nov. can be distinguished from all congeners by having a whitish pink body in life (vs. white or silvery body with a humeral mark or some longitudinal stripes), smaller (vs. larger) eyes (diameter less than vs. greater than maxillary barbel length) and maxillary barbel longer (vs. shorter) than rostral barbel. ‘Henicorhynchus’ thaitui, along with H. horai (Bănărescu, 1986) and H. inornatus (Roberts, 1997), is further distinct from all other congeners in having 9 (vs. 8) branched dorsal-fin rays. Along with H. horai, it differs from all other congeners in the presence of rostral barbels (vs. absent) and 39–41 (vs. 34–36) lateral-line scales. ‘Henicorhynchus’ thaitui differs from H. horai and H. inornatus in the presence of two (vs. one) pairs of maxillary and rostral barbels (vs. only the maxillary barbel in H. inornatus and only the rostral barbel in H. horai); from H. horai in having fewer vertebrae (34 vs. 38–41), and a laterally compressed body (vs. cylindrical in H. horai); and from H. inornatus in having 39–40 (vs. 35 in H. inornatus) lateral-line pored scales, and in the absence of a humeral mark (vs. present in H. inornatus).
Etymology: The specific name is a noun in the genitive case, honoring Nguyen Thai Tu, ichthyologist from Vinh University, who has contributed considerably to the taxonomy of freshwater fishes in Vietnam.
Dinh Tao Nguyen, Anh Tuan Ho, Ngoc Thao Hoang, Hua Wu and E Zhang. 2020. ‘Henicorhynchus’ thaitui, A New Species of Cavefish from Central Vietnam (Teleostei, Cyprinidae). ZooKeys. 965: 85-101. DOI: 10.3897/zookeys.965.52751
