72 



P.R. PUGH 



proximal region of the cnidoband of both species. However, those of 

 Bargmannia spp. are considerably larger than those off! vanhoeffeni, 

 which measure c. 40 x 28 mm. Further, the other nematocysts 

 present on the cnidoband and terminal filament are very similar. Two 

 types of small nematocysts were found in Bargmannia spp. and 

 similar ones, measuring 13-17 x 9.5-10.5 urn and 6.5 x 6.5 urn, 

 were found in P. vanhoeffeni. Although the tentillum of Erenna has 

 a straight cnidoband, and that of Marrus is loosely coiled or straight, 

 the types and distribution of the nematocysts are quite different. The 

 cnidoband of Erenna is massively armed with two types of elongate 

 nematocysts, measuring c. 160 x 37 um and c. 35 x 18 urn, while the 

 terminal process appears to be devoid of any nematocyst The 

 cnidoband of Marrus contains heteronemes and haplonemes, meas- 

 uring c. 55 x 20 um and c. 35 x 7 um of the type often seen in other 

 agalmatid species. The terminal filament of the latter species con- 

 tains only small nematocysts, probably desmonemes, acrophores or 

 anacrophores, measuring c. 16 x 9.5 um and c. 10 x 10 um. These 

 differences in the nematocyst types alone seem sufficient to indicate 

 that Bargmannia and Pyrostephos are more closely related to each 

 other than either is to Marrus or Erenna. 



Despite all these similarities between Bargmannia spp. and Pyro- 

 stephos vanhoeffeni, there are at least two major differences: 

 Bargmannia spp. are the only physonect siphonophores known to 

 have siphosomal tentacles, though apolemiid species have nectosomal 

 ones; they also lack dactylozooids, although the bud-like structures 

 may be vestigial ones. In addition, P. vanhoeffeni is the only species 

 known to have highly modified dactylozooids, the oleocysts, without 

 palpacles.The only other species in which dactylozooids are thought 

 to be absent is Marrus orthocanna (Andersen, 1981). However, 

 Totton (1965) reported that palpons are present on the gonodendra of 

 M. antarcticus. Further work needs to be carried out on well-preserved 

 specimens of IheseMarrus species in order to investigate this apparent 

 difference, and whether each is monoecious or dioecious. 



Although there are major differences between Bargmannia spp. 

 and Pyrostephos vanhoeffeni, there appear to be sufficient similari- 

 ties to warrant the retention of the genus Bargmannia in the family 

 Pyrostephidae. The alternative would be to propose a new family for 

 it, since the genus certainly does not fit neatly into the family 

 Agalmatidae. This might also apply to the genera Marrus and 

 Erenna but their species are too little known. 



ACKNOWLEDGEMENTS. I am extremely grateful to Drs Richard Harbison 

 and Edie Widder for inviting me to participate in several cruises involving the 

 use of submersibles, and for donating the siphonophore material collected to 

 me. I thank Dr Paul Cornelius for his helpful comments on the manuscript. 



REFERENCES 



Alvarino,A. 1963. Chaetognatha. Siphonophora. and Medusae in the Gulf of Siam and 

 the South China Sea. Report on the results of the NAGA Expedition - South East Asia 

 Research Project. Scripps Institution of Oceanography: 104—108. 



1964. Report on the Chaetognatha, Siphonophorae. and Medusae of the 



MONSOON Expedition to the Indian Ocean. Report. Scripps Institute of Oceanog- 

 raphy. SIORef. Ser. 64/19: 103-108,209-212. 



Andersen, O.G.N. 1 98 1 . Redescription of Marrus orthocanna(Kiamp. 1 942 ) (Cnidaria. 



Siphonophora). Steenstrupia 7: 293-307. 

 Carre, C. & Carre, D. 1995. Ordre des Siphonophores. pp. 523-596 in Traite de 



Zoologie. Anatomie, Systematique. Biologic Tome 111. Fascicule 2. Cnidaires. 



Cte'naires. ed. D. Doumenc. Masson. Paris. 

 Daniel, R. 1974. Siphonophora from the Indian Ocean. Memoirs of the Zoological 



Suney of India 15(4): 1-242. 



1985. Coelenterata: Hydrozoa Siphonophora The fauna of India and adjacent 



countries, Zoological Survey of India, 440 pp. 



Herre, W. 1955. Die Fauna der miozanen Spaltenfullung von Neudorf a.d. Match 



(CSR.). Amphibia (Urodela). Sitzungsberichte der Osterreichische Akademie der 



Wissenschaften. Mathematisch-naturwissenschaftliche Klasse. Abteilung I, 164: 



783-803. 

 Kirkpatrick, P.A. & Pugh, P.R. 1984. Siphonophores and Velellids. Synopses of the 



British Fauna (New Series) 29: 1-154. 

 Leloup, E. 1 955. Siphonophores. Report on the Scientific Results of the 'Michael Sars' 



North Atlantic Deep-Sea Expedition 1910 5(11): 1-24. 

 Mackie, G.O. 1964. Analysis of locomotion of a siphonophore colony. Proceedings of 



the Royal Society of London, B 159: 366-391. 

 Pugh, P.R. & Purcell, J.E. 1987. Siphonophore biology. Advances in Marine 



Biology 24: 97-262. 

 Mapstone, G.M. 1998. Bargmannia lata, an undescribed species of physonect 



siphonophore (Cnidaria. Hydrozoa) from Canadian Pacific waters Zoologische 



Verhandelingen 323: 141-147. 

 Pages, F, Pugh, P.R. & Gili J-M. 1994. Macro- and megaplanktonic cnidarians 



collected in the eastern part of theWeddell Gyre during summer 1979 . Journal of the 



Marine Biological Association of the United Kingdom 74: 873-894. 

 Pugh, P.R. 1983 Benthic Siphonophores. A review of the Family Rhodaliidae 



(Siphonophore, Physonectae). Philosophical Transactions of the Royal Society of 



London B 301: 165-300. 

 1984. The diel migrations and distributions within a mesopelagic community in 



the North east Atlantic. 7. Siphonophores. Progress in Oceanography 13: 461-489. 



1998. A re-description of Frillagalma vityazi Daniel 1966 (Siphonophorae, 



Agalmatidae). Scientia Marina 62: 233-245. 



& Harbison, G.R. 1986. New observations on a rare physonect siphonophore, 



Lychnagalma utricularia (Claus, 1879). Journal of the Marine Biological Associa- 

 tion of the United Kingdom 66: 695-710. 



& Youngbluth, M.J. 1988. A new species of Halistemma (Siphonophora. 



Physonectae. Agalmidae) collected by submersible. Journal of the Marine Biologi- 

 cal Association of the United Kingdom 68: 1-14. 



Stepanjants, S.D. 1967. Siphonophores of the seas of the USSR and the north western 

 part of the Pacific Ocean. Opredeliteli po Faune SSSR 96: 1-216. 



Totton, A.K. 1954. Siphonophora of the Indian Ocean together with systematic and 

 biological notes on related specimens from other oceans. Discovery Reports 27: I- 

 162. 



1965. A Synopsis of the Siphonophora. London: British Museum (Natural 



History). 



