On May 23, 2012 during observation of the spring plankton in the Rugozerskaya Bay, Dr. Andrei Prudkovskiy, PhD (Biology)and a research fellow of the Invertebrate Zoology department, found a new hydrozoan medusa, previously never seen in this area — Hybocodon prolifer. Now this species will be added to the Catalogue of Biota of the MSU White Sea Biological Station.
About the finding of the hydrozoan Hybocodon prolifer (Cnidaria, Hydrozoa, Anthomedusae, Capitata, Tubulariidae)in the vicinity of WSBS MSU
Dr. A. Prudkovskiy, PhD, MSU Department of Invertebrate Zoology
Previously, this species of hydrozoan medusae, also known as Tubularia prolifer, has been found sporadically in the Mezen Bay, the Neck and in the Basin of the White Sea (Pertsova, 1979). Such occurrence allowed to assume that this hydrozoan species was brought from the Barents Sea. However, on May 23, 2012, the Hybocodon prolifer medusa was caught in the vicinity of the Biological Station (in the Rugozerskaya Bay of the Kandalaksha Bay). It was caught at low tide in the coastal zone, among algae, in the direction of the Eremeevsky porog rapids. On that day, the surface water temperature at the WSBS pier was 3-5 degrees above zero.
It was a young specimen with bell height of 3.5 mm, underdeveloped gonads, and a bud of a secondary medusa on its tentacular bulb.
Specific morphology features of Hybocodon prolifer: This species of medusae is characterized by one well-developed tentacular bulb, which is divided into three parts and has three tentacles. Other three bulbs are underdeveloped and have no tentacles. New medusa buds develop on the main bulb. The bell has four radial canals, and the exumbrella has five rows of nematocysts. The manubrium is elongated, though it does not go beyond the bell. The mouth is simple, surrounded by a ring of nematocysts. On the manubrium of adult specimen, gonads and after fertilization, actinula larvae are formed.
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