Abstract
Aenigmachanna gollum, new genus and species, is described from Kerala, South India. It is the first subterranean species of the family Channidae. It has numerous derived and unique characters, separating it from both the Asian Channa Scopoli and the African Parachanna Teugels & Daget. Uniquely among channids, A. gollum has a very slender (maximum body depth only 11.1–11.3% SL), eel-like body (head length 20.8–21.6% SL), large mouth (jaw length 60.4–61.1 % HL), 43–44 anal-fin rays, 83–85 scales in a lateral series, an unusual colour pattern and it lacks pored lateral-line scales on the body and body buoyancy. In addition, it is distinguished by its DNA barcode sequence, which is 15.8–24.2% divergent from other species of the family Channidae. Morphological modifications usually associated with a subterranean life, such as reduction of eyes and enhancement of non-visual senses (taste, smell, mechanosensory systems) are absent in A. gollum. However, it shares with subterranean fishes a slight reduction of its pigmentation in comparison to epigean channids.
References
Abell, R., Thieme, M.L., Revenga, C., Bryer, M., Kottelat, M., Bogutskaya, N., Coad, B., Mandrak, N., Balderas, S.C., Bussing, W., Stiassny, M.L.J., Skelton, P. Allen, G.R., Unmack, P., Naseka, A., Ng, R., Sindorf, N., Robertson, J., Armijo, E., Higgins, J.V., Heibel, T.J., Wikramanayake, E., Olson, D., Lopez, H.L., Reis, R.E. Lundberg, J.G., Sabaj-Pérez, M.H. & Petry, P. (2008) Freshwater ecoregions of the world: A new map of biogeographic units for freshwater biodiversity conservation. Bioscience, 58, 403–414.
https://doi.org/10.1641/B580507
Ali, A., Dahanukar, N., Kanagavel, A., Philip, S. & Raghavan, R. (2013) Records of the endemic and threatened catfish, Hemibagrus punctatus from the southern Western Ghats with notes on its distribution, ecology and conservation status. Journal of Threatened Taxa, 5, 4569–4578.
https://doi.org/10.11609/JoTT.o3427.4569-78
Altschul, S.F., Gish, W., Miller, W., Myers, E.W. & Lipman, D.J. (1990) Basic local alignment search tool. Journal of Molecular Biology, 215, 403–410.
https://doi.org/10.1016/S0022-2836(05)80360-2
Bader, R. (1937) Bau, Entwicklung und Funktion des akzessorischen Atmungsorganes der Labyrinthfische. Zeitschrift für wissenschaftliche Zoologie, 149, 323–401.
Bailey, R.M. & Gans, C. (1998) Two new synbranchid fishes, Monopterus roseni from Peninsular India and M. desilvai from Sri Lanka. Occasional Papers of the Museum of Zoology University of Michigan, 726, 1–18.
https://doi.org/10.1371/journal.pone.0060615
Bansal, R. & Karanth, K.P. (2013) Phylogenetic analysis and molecular dating suggest that Hemidactylus anamallensis is not a member of the Hemidactylus radiation and has an ancient Late Cretaceous origin. PLOS One, 8, e60615.
Benziger, A., Philip, S. Raghavan, R., Ali, P.H.A., Sukumaran, M. Tharian, J.C., Dahanukar, N., Baby, F., Peter, R., Rema Devi, K., Radhakrishnan, K.V., Haniffar, M.A., Britz, R. & Antunes, A. (2011) Unraveling a 146 years old taxonomic puzzle: validation of Malabar snakehead, species-status and its relevance for channid systematics and evolution. PLoS ONE, 6, e21272.
https://doi.org/10.1371/journal.pone.0021272
Biju, S.D. & Bossuyt, F. (2003) New frog family from India reveals an ancient biogeographical link with the Seychelles. Nature, 425, 711–714.
https://doi.org/10.1038/nature02019
Bonou, C.A. & Teugels, G.G. (1985) Révision systématique du genre Parachanna Teugels et Daget 1984 (Pisces: Channidae). Revue d’Hydrobiologie Tropicale, 18, 267–280.
Borowsky, R. (2018) Cavefishes. Current Biology, 28, 51–65. [R51–R65]
https://doi.org/10.1016/j.cub.2017.12.011
Britz, R. (2008) Channa ornatipinnis and C. pulchra, two new species of dwarf snakeheads from Myanmar (Teleostei: Channidae). Ichthyological Exploration of Freshwaters, 18, 335–344.
Britz, R., Lalremsanga, H.T., Lalrotluanga & Lalramliana (2011) Monopterus ichthyophoides, a new species of scaled swamp eel (Teleostei: Synbranchiformes: Synbranchidae) from Mizoram, India. Zootaxa, 2936 (1), 51–58.
https://doi.org/10.11646/zootaxa.2936.1.2
Britz, R., Kakkassery, F. & Raghavan, R. (2014) Osteology of Kryptoglanis shajii, a stygobitic catfish (Teleostei: Siluriformes) from Peninsular India with a diagnosis of the new family Kryptoglanidae. Ichthyological Exploration of Freshwaters, 24, 193–207.
Britz, R., Doherty-Bone, T.M., Kouete, M.T., Sykes, D. & Gower, D.J. (2016) Monopterus luticolus, a new species of swamp eel from Cameroon (Teleostei: Synbranchidae). Ichthyological Exploration of Freshwaters, 27, 309–323.
Britz, R., Sykes, D., Gower, D.J. & Kamei, R.G. (2018) Monopterus rongsaw, a new species of hypogean swamp eel from the Khasi Hills in Northeast India (Teleostei: Synbranchiformes: Synbranchidae). Ichthyological Exploration of Freshwaters, 28, 315–326.
Collins, R.A., Britz, R. & Rüber, L. (2015) Phylogenetic systematics of leaffishes (Teleostei: Polycentridae, Nandidae). Journal of Zoological Systematics and Evolutionary Research, 53, 259–272.
https://doi.org/10.1111/jzs.12103
Dahanukar, N., Raghavan, R, Ali, A., Abraham, R. & Shaji, C.P. (2011) The status and distribution of freshwater fishes of the Western Ghats. In: Molur, S., Smith, K.G., Daniel, B.A. & Darwall, W.R.T. (Eds.), The status and distribution of freshwater biodiversity in the Western Ghats, India. IUCN, Cambridge, pp. 21–48.
Dahanukar, N., Philip, S., Krishnakumar, K., Ali, A. & Raghavan, R. (2013) The phylogenetic position of Lepidopygopsis typus (Teleostei: Cyprinidae), a monotypic freshwater fish endemic to the Western Ghats of India. Zootaxa, 3700 (1), 113–139.
https://doi.org/10.11646/zootaxa.3700.1.4
Deepak, V., Ruane, S. & Gower, D.G. (2018) A new subfamily of fossorial colubroid snakes from the Western Ghats of peninsular India. Journal of Natural History, 52, 2919–2934.
https://doi.org/10.1080/00222933.2018.1557756
Eapen, K.C. (1963) A new species of Monopterus from south India. Bulletin of the Department of Marine Biology Oceanography, University of Kerala, 1, 129–132.
Edgar, R.C. (2004) MUSCLE: Multiple sequence alignment with high accuracy and high throughput. Nucleic Acids Research, 32, 1792–1797.
https://doi.org/10.1093/nar/gkh340
Day, F. (1868) Observations on some of the freshwater fishes of India. Proceedings of the Zoological Society of London, 19, 274–288.
De Grave, S., Arjun, C.P. & Raghavan, R. (2018) The discovery of Euryrhynchidae (Crustacea: Decapoda) in India, with the description of a new genus and species. Zootaxa, 4462 (3), 367–378.
https://doi.org/10.11646/zootaxa.4462.3.4
Gopi, K.C. (2002) A new synbranchid fish, Monopterus digressus from Kerala, Peninsular India. Records of the Zoological Survey of India, 100, 137–143.
Gunawardene, N.R., Daniels, A.E.D., Gunatilleke, I.A.U.N., Gunatilleke, C.V.S., Karunakaran, P.V., Geetha Nayak, K., Prasad, S., Puyravaud, P., Ramesh, B.R., Subramanian, K.A. & Vasanthy, G. (2007) A brief overview of the Western Ghats-Sri Lanka biodiversity hotspot. Current Science, 93, 1567–1572.
Kumar, S., Stecher, G. & Tamura, K. (2016) MEGA7: Molecular evolutionary genetics analysis version 7.0 for bigger datasets. Molecular Biology and Evolution, 33, 1870–1874.
https://doi.org/10.1093/molbev/msw054
Lanfear, R., Calcott, B., Ho, S.Y. & Guindon, S. (2012) PartitionFinder: Combined selection of partitioning schemes and substitution models for phylogenetic analyses. Molecular Biology and Evolution, 29, 1695–1701.
https://doi.org/10.1093/molbev/mss020
Liem, K.F. (1980) Air ventilation in advanced teleosts: biomechanical and evolutionary aspects. In: Ali, M.A. (Ed.), Environmental physiology of fishes. Plenum Press, New York, pp. 57–91.
Menon, A.G.K. (1950) On a remarkable blind siluroid fish of the family Clariidae from Kerala (India). Records of the Indian Museum, 48, 59–66.
Minh, B.Q., Nguyen, M.A.T. & von Haeseler, A. (2013) Ultrafast approximation for phylogenetic bootstrap. Molecular Biology and Evolution, 30, 1188–1195.
https://doi.org/10.1093/molbev/mst024
Mittermeier, R.A., Turner, W.R., Larsen, F.W., Brooks, T.M. & Gascon, C. (2011) Chapter 1 Global Biodiversity Conservation: The Critical Role of Hotspots. In: Zachos, F.E. & Habel, J.C. (Eds.), Biodiversity Hotspots. Springer-Verlag, Berlin, pp. 3–22.
Mo, T. (1991) Anatomy, relationships and systematics of the Bagridae (Teleostei, Siluroidei) with a hypothesis of siluroid phylogeny. Theses Zoologicae 17. Koeltz, Koenigstein, vii + 216 pp.
Myers, N., Mittermeier, R.A., da Fonseca, G.A.B. & Kent, J. (2000) Biodiversity hotspots for conservation priorities. Nature, 403, 853–857.
https://doi.org/10.1038/35002501
Nei, M. & Kumar, S. (2000) Molecular evolution and phylogenetics. Oxford University Press, Oxford, 333 pp.
Nguyen, L.T., Schmidt, H.A., von Haeseler, A. & Minh, B.Q. (2015) IQ- TREE: A fast and effective stochastic algorithm for estimating maximum likelihood phylogenies. Molecular Biology and Evolution, 32, 268–274.
https://doi.org/10.1093/molbev/msu300
Paveenraj, J., Uma, A., Moulitharan, N. & Singh, S.G. (2019) A new species of dwarf Channa (Teleostei: Channidae) from Meghalaya, Northeast India. Copeia, 107, 61–70.
Proudlove, G.S. (2019) Subterranean Fishes of the World. An account of the subterranean (hypogean) fishes with a bibliography from 1436. Available from: https://cavefishes.org.uk/ (accessed 10 April 2019)
Rambaut, A. (2016) FigTree. Version 1.4.3. [Software]. Available from: http://tree.bio.ed.ac.uk/software/figtree (accessed 17 April 2019)
San Mauro, D., Gower, D.J., Müller, H., Loader, S.P., Zardoya, R., Nussbaum, R.A. & Wilkinson, M. (2014) Life-history evolution and mitogenomic phylogeny of caecilian amphibians. Molecular Phylogenetics and Evolution, 73, 177–189.
Schwarz, G. (1978) Estimating the dimension of a model. The Annals of Statistics, 6, 461–464.
https://doi.org/10.1214/aos/1176344136
Vijayakumar, S.P., Pyron, R.A., Dinesh, K.P., Torsekar, V.R., Srikanthan, A.N., Swamy, P., Stanley, E.L., Blackburn, D.C. & Shanker, K. (2019) A new ancient lineage of frog (Anura: Nyctibatrachidae: Astrobatrachinae sub fam.nov.) endemic to the Western Ghats of India. Peer J, 7, e6457.
https://doi.org/10.7717/peerj.6457
Vincent, M. & Thomas, J. (2011) Kryptoglanis shajii, an enigmatic subterranean-spring catfish (Siluriformes, Incertae sedis) from Kerala, India. Ichthyological Research, 58, 161–165.
Ward, R.D., Zemlak, T.S., Innes, B.H., Last, P.R. & Hebert, P.D. (2005) DNA barcoding Australia’s fish species. Philosophical Transactions of the Royal Society B: Biological Sciences, 360, 1847–1857.
https://doi.org/10.1098/rstb.2005.1716
Wilkens, H. & Strecker, U. (2017) Evolution in the Dark—Darwin’s loss without selection. Springer, Berlin, 217 pp.