Snakehead (Teleostei: Channidae) diversity and the Eastern Himalaya biodiversity hotspot

Abstract

The collision of the Indian and Eurasian landmasses in the Cenozoic was a decisive factor in shaping biodiversity patterns in Southern and Southeastern Asia. While most studies thus far have focused on the biotic interchange between India and Eurasia and evolutionary diversification on or around the Tibetan Plateau, little attention has been paid to the biodiversity buildup in the Eastern Himalaya biodiversity hotspot (EHH) which harbors over 540 freshwater fish species with a high degree of endemicity. An important component of the regional ichthyofauna are snakehead fishes of the family Channidae comprising throughout their African‐Asian distribution 47 valid species, but a poorly known species‐level diversity. In order to evaluate channid intrarelationships and biogeography, a temporal and geographic framework of channid evolution in conjunction with a critical reevaluation of the channid fossil record is warranted. Based on molecular data, we provide a comprehensive species‐level phylogeny based on 223 channid individuals belonging to 37 species and one additional currently undescribed species. The first split within channids separates the African genus Parachanna from the Asian genus Channa which can be divided into eight distinct species groups (Argus, Asiatica, Gachua, Lucius, Marulius, Micropeltes, Punctata, and Striata groups). Large intraspecific divergences were observed within several species and potentially indicate additional species‐level diversity. Almost 40% of the channid species are narrow‐range endemics belonging to the Gachua group. These are found in the EHH making this area an outstanding hotspot for endemic channid diversity. The large majority of the EHH endemics are restricted to the southern foothills of the Eastern Himalaya and the Shillong‐Mikir Hills Plateau, areas west of the Indoburman Ranges. Our results reveal complex and difficult to interpret biogeographic patterns indicating that both vicariance and dispersal events have potentially been responsible in shaping current distribution patterns in Asian channids. We recognize †Parachanna fayumensis as the oldest reliable channid fossil and argue that the three oldest so‐called channid fossils (i.e., †Eochanna chlorakkiensis, †Anchichanna kuldanensis, and †Ophiocephalus lydekkeri) lack clear diagnostic features that would allow them to be unequivocally placed within Channidae.

Aenigmachannidae, a new family of snakehead fishes (Teleostei: Channoidei) from subterranean waters of South India

“…Applying the crown calibration, the range of our minimum age estimate of 83-136 million years for the Aenigmachanna lineage takes it back to the period when the Gondwana supercontinent started to break up and India/Madagascar separated from Africa at around 120 million years ago. This would indicate that the presence of Aenigmachanna and Channa in Asia and Parachanna in Africa is the result of vicariance, as recently hypothesized for the Channidae 30 . With the alternative stem calibration and the resulting minimum age of 33-35 million years, a Gondwana vicariance scenario appears less likely, though is still possible.…”

“…c. Accessory breathing organs with respiratory nodules on first and second epibranchials, hyomandibular, and parasphenoid (30). Aenigmachanna lacks a suprabranchial cavity and a suprabranchial organ altogether ( Fig.…”

“…A detailed analysis and characterization of the mt genome of Aenigmachanna is in preparation. For newly determined sequences other than for Aenigmachanna, the protocols for DNA extraction, PCR primers and PCR conditions and sequencing by LGC Genomics, Berlin follow previous protocols 30,[52][53][54][55] . For the sh3px3, the nested PCR protocol of Li et al 56 was used.…”

“…We used the channid fossil † Parachanna fayumensis 66 from the Jebel Qatrani Formation , Fayum Depression in Egypt , Late Eocene to Oligocene (about 35-33 mya) and the anabantoid fossil Osphronemus from the Sangkarewang Formation in Central Sumatra 67 , a formation dating back to the Early Oligocene to Late Eocene age (28.5-37.0 mya). Following Rüber et al 30 these two lognormal calibration priors from the fossil record were used: TMRCA Parachanna crown (offset 33.0; 37.0 Mya 95% soft upper bound; log mean = 0.1; log stdev = 0.8) and the TMRCA Osphronemus crown (offset 28.5; 35.0 Mya 95% soft upper bound; log mean = 0.23; log stdev = 1.0). Alternative calibrations were conducted assigning the Parachanna and Osphromenus fossils to their respective stem groups as in 30 .…”

“…Some species have become highly invasive outside of their native range and two species are now established in the United States 28,29 . Snakehead fishes have parental care and either primitively guard a nest of floating eggs at the water surface or, as a more derived condition, are mouthbrooders 30 .…”