Additional description of the Algae Hydroid Thyroscyphus ramosus (Hydrozoa: Leptothecata: Thyroscyphidae) from Palk Bay, India with insights into its ecology and genetic structure

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G. Arun
R. Rajaram
K. Kaleshkumar


The Algae hydroid Thyroscyphus ramosus of the Indian subcontinent is the most easily recognizable fleshy colonial hydroid playing a vital role in benthic communities.  Though this fauna is abundant, it has remained unexplored for the past nine decades in India.  This study provides a detailed report of the morphology, ecology and geographical locations of T. ramosus.  Morphological traits such as maximum height, gonophore, and theca twist directions were studied in detail.  The molecular biological data confirms the identity of T. ramosus and its abundance in Palk Bay, India.  Important molecular markers such as 18S, 16S rRNA sequences of T. ramosus were analyzed and compared with similar species in NCBI.  Using 18S sequence data, it is proven that T. ramosus is a distinct and valid species, however, interestingly the 16S rRNA forms clades with other species of the same genera (T. fruticosus and T. bedoti) rather than the same species.  Moreover the mtCOI forms a different clade with other genera. Furthermore, these data may enhance the advancement of identification in non-monophyletic conditions. 


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Allman, G.J. (1888). Report on the Hydroida dredged by H.M.S. Challenger during the years 1873-1876. Part I. Plumularidae. Report on the scientific results of the voyage of H.M.S. Challenger 1873–1876. Zoology 7: 1–54. DOI:

Allman, G.J. (1877). Report on the Hydroida : collected during the exploration of the Gulf Stream by L. F. de Pourtalès, assistant United States Coast Survey. Welch, Bigelow and Company, University Press, Cambridge, 166pp.

Boero, F., J. Bouillon, C. Gravili, M.P. Miglietta, T. Parsons & S. Piraino (2008). Gelatinous plankton: irregularities rule the world (sometimes). Marine Ecology Progress Series 356: 299–310. DOI:

Bouillon, J., C. Gravili, J.M. Gili & F. Boero (2006). An introduction to Hydrozoa. Memories of the National Museum of Natural History Volume 194, Museum Scientific Publications, Paris, 591pp.

Calder, D.R. & S.D. Cairns (2009). Hydroids (Cnidaria: Hydrozoa) of the Gulf of Mexico, Pp. 381–394 In: Felder, D.L. & D.K. Camp (eds.), Gulf of Mexico, Origins, Waters, and Biota. Volume 1, Biodiversity, Texas A&M University Press, College Station, 1393pp.

Collins, A.G., S. Winkelmann, H. Hadrys & B. Schierwater (2005). Phylogeny of Capitata and Corynidae (Cnidaria, Hydrozoa) in light of mitochondrial 16S rDNA data. Zoologica Scripta 34(1): 91–99. DOI:

Collins, A.G., P. Schuchert, A.C. Marques, T. Jankowski, M. Medina & B. Schierwater (2006). Medusozoan phylogeny and character evolution clarified by new large and small subunit rDNA data and an assessment of the utility of phylogenetic mixture models. Systematic Biology 55(1): 97–115. DOI:

Di Camillo, C.G., M. Bo, S. Puce & G. Bavestrello (2010). Association between Dentithecahabereri (Cnidaria: Hydrozoa) and two zoanthids. Italian Journal of Zoology 77(1): 81–91. DOI:

Di Camillo, C.G., G. Bavestrello, C. Cerrano, C. Gravili, S. Piraino, S. Puce & F. Boero (2017). Hydroids (Cnidaria, Hydrozoa): a neglected component of animal forests, pp. 397-427. In: Marine Animal Forests: The Ecology of Benthic Biodiversity Hotspots, Springer, Cham, 1366pp. DOI:

Di Camillo, C.G., G.M. Luna, M. Bo, G. Giordano, C. Corinaldesi & G. Bavestrello (2012). Biodiversity of prokaryotic communities associated with the ectoderm of Ectopleura crocea (Cnidaria, Hydrozoa). PLoS One 7(6): e39926. DOI:

Galea, H.R. (2008). On a collection of shallow-water hydroids (Cnidaria: Hydrozoa) from Guadeloupe and Les Saintes, French Lesser Antilles. Zootaxa 1878: 1–54.

Govindarajan, A.F., F. Boero & K.M. Halanych (2006). Phylogenetic analysis with multiple markers indicates repeated loss of the adult medusa stage in Campanulariidae (Hydrozoa, Cnidaria). Molecular Phylogenetics and Evolution 38(3): 820­–834. DOI:

González-Duarte, M.M., C. Megina, & S. Piraino (2014). Looking for long-term changes in hydroid assemblages (Cnidaria, Hydrozoa) in Alboran sea (south-western Mediterranean): a proposal of a monitoring point for the global warming. Helgoland Marine Research, 68: 511–521. DOI:

Gravely, F.H. (1927). The littoral fauna of Krusudai Island in the Gulf of Mannar, orders Decapoda (except Paguridae) and Stomatopoda. Bulletin of the Madras Government Museum 1: 135–155.

Hissmann, K. (2005). In situ observations on benthic siphonophores (Physonectae: Rhodaliidae) and descriptions of three new species from Indonesia and South Africa. Systematics and Biodiversity 2(3): 223–249. DOI:

Hora, L.S. (1925). In A collection of hydropolypes belonging to the Indian Museum in Calcutta. Records of the Indian Museum, 179pp.

Hughes, L (2000). Biological consequences of global warming: is the signal already apparent?. Trends in Ecology & Evolution, 15(2): 56-61. DOI:

Kelmo, F. & R. Vargas (2002). Anthoathecatae and Leptothecatae hydroids from Costa Rica (Cnidaria: Hydrozoa). Revista de Biología Tropical 50(2): 599–627.

Kumaraguru, A.K., V. Edwin Joseph, M. Rajee & T. Balasubramanian (2008). Palk Bay - Information and Bibliography, CAS in Marine Biology, Annamalai University, Parangipettai and Centre for Marine and Coastal Studies, Madurai Kamaraj University, Madurai, 227pp.

Leloup, E. (1932). A collection of hydropolypes belonging to the Indian Museum in Calcutta. Records of the Indian Museum, 34(2): 131–170.

Maggioni, D., S. Montano, D. Seveso & P. Galli (2016). Molecular evidence for cryptic species in Pteroclavakrempfi (Hydrozoa, Cladocorynidae) living in association with alcyonaceans. Systematics and Biodiversity 14(5): 484–493. DOI:

Migotto, A.E. & W. Vervoort (1996). The benthic shallow water hydroids (Cnidaria, Hydrozoa) of the coast of São Sebastião, Brazil, including a checklist of Brazilian hydroids. Nationaal Natuurhistorisch Museum, 306: 25-125.

Mammen, T.A. (1963). On a collection of hydroids from South India. I. Suborder Athecata. Journal of the Marine Biological Association of India 5(1): 27–61.

Mammen, T.A. (1965a). On a collection of hydroids from South India. III. Family Plumulariidae. Journal of the Marine Biological Association of India 7(1): 291–324.

Mammen, T.A. (1965b). On a collection of hydroids from South India. II. Suborder Thecata (excluding family Plumulariidae). Journal of the Marine Biological Association of India 7: 1–57.

Migotto, A.E., C.G. Tiago & A.R.M Magalhaes (1993). A faunal survey of the marine molluscs of the Channel of São Sebastião, SP, Brazil: Gastropoda, Bivalvia, Polyplacophora and Scaphopoda. Bulletin of the Instituto Oceanografico, 41(1–2): 13–27. DOI:

Mandal, A., M. Varkey, S.P. Sobhanan, A.K. Mani, A. Gopalakrishnan, G. Kumaran, A. Sethuramalingam, P. Srinivasan & Y.C.T. Samraj (2014). Molecular markers reveal only two mud crab species of genus Scylla (Brachyura: Portunidae) in Indian coastal waters. Biochemical Genetics 52(7–8): 338–354. DOI:

Kasim, M.H. (2015). Resources and livelihoods of the Palk Bay: Information from India & Sri Lanka. Conference: International Academic Workshop Resources Conservation and Alternate Livelihood Opportunities in Coastal Tamil Nadu (ReCAL’15), 28pp.

Moura, T., M.C. Silva, I. Figueiredo, A. Neves, P.D. Munoz, M.M. Coelho & L.S. Gordo (2008). Molecular barcoding of north-east Atlantic deep-water sharks: species identification and application to fisheries management and conservation. Marine and Freshwater Research 59(3): 214–223. DOI:

Nikulina, E.A., H. De Blauwe & O. Reverter-Gil (2013). Molecular phylogenetic analysis confirms the species status of Electra verticillata (Ellis and Solander, 1786), pp 217-236. In: Ernst, A. et al. (Ed.) Bryozoan Studies 2010. Lecture Notes in Earth System Sciences, Springer, Berlin, Heidelberg, 448pp. DOI:

Nutting, C.C. (1915). American Hydroids. Part 3, The Campanularidae and the Bonneviellidae. Species Bulletin - United States National Museum (Washington) 27–126

Orejas, C., J.M. Gili, V. Alvà & W. Arntz (2000). Predatory impact of an epiphytic hydrozoan in an upwelling area in the Bay of Coliumo (Dichato, Chile). Journal of Sea Research, 44: 209–220. DOI:

Owen, R. (1843). Lectures on the comparative anatomy and physiology of the invertebrate animals: delivered at the Royal College of Surgeons, London, Longman, Brown, Green and Longmans, pp392. DOI:

Schierwater, B. & A. Ender (2000). Sarsiamarii n. sp. (Hydrozoa, Anthomedusae) and the use of 16S rDNA sequences for unpuzzling systematic relationships in Hydrozoa. Scientia Marina 64: 117–122. DOI:

Schuchert, P. (2014). High genetic diversity in the hydroid Plumulariasetacea: a multitude of cryptic species or extensive population subdivision? Molecular Phylogenetics and Evolution 76: 1–9. DOI:

Shimabukuro, V.A.N.E.S.S.A. & A.C. Marques (2006). Morphometrical analysis, histology, and taxonomy of Thyroscyphusramosus (Cnidaria, Hydrozoa) from the coast of Brazil. Zootaxa 1184(1): 29–42. DOI:

Trivedi, S., A.A. Aloufi, A.A. Ansari & S.K. Ghosh (2016). Role of DNA barcoding in marine biodiversity assessment and conservation: an update. Saudi Journal of Biological Sciences 23(2): 161–171. DOI:

Gemerden-Hoogeveen, van G.C.H. (1965). Hydroids of the Caribbean: Sertulariidae, Plumulariidae and Aglaopheniidae. Studies on the fauna of Curacao and other Caribbean Islands 22(1): 1–87.

Vervoort, W. (1959). The Hydroida of the tropical west coast of Africa. Atlantide Report. Scientific Results of the Danish Expedition to the coasts of tropical West Africa, 1945–1946. Copenhagen, Danish Science Press, pp325.

Warren, E. (1907). On Parawrightiarobusta gen. et sp. nov., a hydroid from the Natal coast; and also an account of a supposed schizophyte occurring in the gonophores. Annals of the Natal Government Museum 1: 187–208.

Winston, J.E. (1982). Marine bryozoans (Ectoprocta) of the Indian River area (Florida). Bulletin of the American Museum of Natural History, 176pp.

Winston, J.E. (2009). Stability and Change in the Indian River Area Bryozoan Fauna over a Twenty-Four Year Period, pp. 299-240. In: Proceedings of the Smithsonian Marine Science Symposium, Smithsonian Institution Scholarly press, Washington D.C. pp529.