Vallicula multiformis Rankin , 1956 ( Ctenophora , Platyctenida ) : first record from the Indian Ocean

The benthic ctenophore Vallicula multiformis Rankin, 1956 is recorded for the first time in the Arabian Sea, from the Gulf of Kutch, west coast of India in March 2013. This occurrence represents a remarkable extension of its geographic distribution that until now included only known the Pacific and Atlantic oceans.

The Platyctenida, an order of ctenophores that includes the benthic species, has 47 species (Mills 2013).Most of them have restricted geographical distributions, limited to their respective type localities.Vallicula multiformis Rankin, 1956 (family Coeloplanidae) is an exception.The species was originally described from Jamaica (Rankin 1951) and then was recorded from Brazil (Marcus 1957;Oliveira and Migotto 2007), Bermuda (Freeman 1967), Madeira (Wirtz 1998), California USA (Mills and Haddock 2007), the Canary Islands and Cuba (Moro et al. 2011). Mills andHaddock (2007) also cited an occurrence of the species from Hawaii (USA), but the presence of V. multiformis in Hawaii was only formally reported by Carlton and Eldredge (2009) and was considered as non-indigenous to Hawaiian waters.Carlton and Eldredge also reported that V. multiformis may reach high population densities, and they also briefly commented on a possible vector of introduction.Informal reports of the species, with photographic records, were made from Florida, USA, by Hebecca Helm (pers.comm.) and from Germany, by Michael Eitel (pers.comm.).
This paper records the first record of the Vallicula multiformis from the Indian Ocean (Figure 1).The species' geographic distribution includes the Atlantic, Northeastern Pacific Ocean, and Northern Indian oceans.Specimens were recorded from Boria (22°25′12.65″N, 069°13′15.24″E) and Adasaba (22°23′58.43″N, 069°12′52.74″E) Islands near to Poshitra, Gujarat on 30 and 31 March 2013.All specimens were observed on the algae Halimeda opuntia (Figure 2a).Collected species, and the host algae, were placed in a plastic container filled with sea water.Four specimens measuring between 6-10 mm wide were collected during a daytime survey from the shore of Boria Island were photographed in the natural habitat on algae along with the sea slug Elysia pusilla (Bergh, 1872) (Figure 2b).After observing their behavior, the specimens were preserved in 4% formaldehyde with sea water without sedation.Voucher specimens were deposited in the collection the Bombay Natural History Society (BNHS-Cteno-1).Specimens were identified using the identification key by Oliveira et al. (2007) and on the original description of V. multiformis by Rankin (1956).Laboratory observations revealed movements by gliding, creeping, and floating (Figure 2c).The general morphology is as described by Rankin (1956).
Tentacles are long (almost double the total body length).Gastrovascular canals end blindly near the body margins; this is one of the notable characteristics of the genus Vallicula.The color is translucent green with white spots scattered all over the body.Light brown spots are visible only under low reflective light (Figure 2d-e).Discoloration was observed after preservation.
In the natural state during daytime, V. multiformis was sessile, without any movement, and appeared similar to a flatworm or a coeloplana.After 5-6 hours in the collection containers with the algae Halimeda opuntia, the animals detached from the algae and were found to be creeping on the walls of the container and changing body forms.Similar observations were reported by Rankin (1956).Rankin (1956) mentioned that V. multiformis was abundant in June to September and January to March and sparsely found in May, October and early December.In this study, animals were observed from March-April when the water temperature was ca.29°C.
In this study, specimens were exclusively found on the algae Halimeda opuntia.
This paper reports Vallicula multiformis for the first time from the coast of India.This species' presence here may be due to natural, passive dispersal with the currents or may represent an introduction due to shipping (i.e., ballast water or fouling; Carlton and Eldredge, 2009).Molecular studies may offer insights into the origin of this Indian population.

ACKNOWLEDGMENTS
We would like to thank Dr. A.R. Rahmani, Director, BNHS for his constant support and motivation.We are grateful to Bernard Picton, Vinicius Padula and Cynthia Trowbridge who provided valuable comments for the specimen's identification at the Nudibase; to Claudia Mills, Alvaro Migotto and Ada Alamaru for their valuable suggestions.We also thank our colleagues and team members at Gujarat field station for their invaluable support and assistance during the field work.Authors would also like to thank the Ministry of Environment, Forest and Climate Change, Government of India, for their constant support.

Figure 1 .
Figure 1.A: Worldwide distribution of Vallicula multiformis.B: Study area: Gulf of Kutch and reefs of Boria and Adasaba islands.