Chapter 1 1 



Sipunculans and Echiurans of Enewetak Atoll 



DENNIS M. DEVANEY (deceased) 



Bernice P. Bishop Museum 

 Honolulu, Hauxiii 9681 7 



SIPUNCULA 



In 1950, a new sipunculan species, Siphonosoma 

 eniwetoki, was described by Fisher from an intertidal 

 lagoon area off Boken Islet. Studies on the bioerosion of 

 coral and coral rubble by Highsmith (1981) revealed six 

 identified aspidosiphonid sipunculans from Enewetak 

 (reduced to five herein). These sipunculans were con- 

 sidered to be "responsible for more excavations in rubble 

 than in any of the coral species studied" (p. 360). The 

 high proportion of both sipunculans and polychaetes in 

 rubble, compared to those living in coral, was attributed to 

 their feeding on detritus and algae from the rubble sur- 

 faces. 



In another study, examination of deejser parts of the 

 lagoon in September 1980 by the author and Patrick Colin 

 revealed additional sipunculans which were determined by 

 S. J. Edmonds (South Australian Museum). An airlift was 

 used to collect the fauna from soft lagoonal sediment and 

 loose coral rock. Sipunculus indicus, an undetermined 

 juvenile Sipunculus (not S. indicus), and Siphonosoma 

 (Damosiphon) cumanense were recovered at depths be- 

 tween 9 and 21 m. At 15 m under coral rock in the 

 lagoon, a specimen considered to be Paraspidosiphon 

 johnstoni was also collected. In July 1981 a specimen of 

 Phascolosoma nigrescens was recovered from hard substra- 

 tum off the wall of a lagoonal crater (Mike) made by a 

 nuclear detonation. Presently, at least 10 identified species 

 of sipunculans arc considered to occur at Enewetak. A 

 checklist is shown in Table 1. Additional species have been 

 found in a recent (1982) examination of bioturbation- 

 causing organisms in the lagoon sediments (Suchanek and 

 Colin, 1986). 



Stephen and Edmonds (1972) record at least five addi- 

 tional sipunculans from the Marshall Islands: Siphonosoma 

 uastum. Aspidosiphon spinalis, Paraspidosiphon steenstru- 

 pii, and Lithacrosiphon cristatus all from Jaluit Atoll. The 

 last three species are reported in Ikeda (1924). Fischer 

 (1928) described Siphonosoma parvum from the Marshall 



TABLE 1 

 Checklist of Enewetak Sipuncula and Echiura 



Phylum SIPUNCULA 



Family SIPUNCULIDAE 



'Siphonosoma (Damosiphon) cumanense (Keferstein, 1867). 

 'Siphonosoma (Siphonosoma) rotumanum (Shipley, 1898) as 

 'Siphonosoma (Siphonosoma) eniwetoki Fisher, 1950; 

 Fisher, 1950; Stephen and Edmonds, 1972. 

 'Sipunculus indicus Peters, 1850. 

 Family ASPIDOSIPHONIDAE 



Aspidosiphon muelleh Diesing, 1851: Highsmith, 1981. 

 Cloeosiphon aspergillus (Quatrefages, 1865): Highsmith, 



1981. 

 Lithacrosiphon cristatus (Sluiter, 1902). 



Lithacrosiphon gurjanouae Murina, 1967: Highsmith, 



1981. 

 Lithacrosiphon odhneri Fischer, 1922: Highsmith, 1981. 

 Lithacrosiphon (?) uniscutatus (Ikeda, 1904): Highsmith, 



1981. 

 Paraspidosiphon gigas (Sluiter, 1884): Highsmith, 1981. 

 'Paraspidosiphon johnstoni Edmonds, 1980. 

 Family PHASCOLOSOMATIDAE 



'Phascolosoma (Phascolosoma) nigrescens Keferstein, 

 1865. 



Phylum ECHIURA 

 Order ECHIUROINEA 

 Family BONELLIIDAE 



'Achaetobonellia maculata Fisher, 1953. 

 •Family ECHIURIDAE 

 Anelassorhi;nchus? sp. 



'New Enewetak record. 



Islands without further locality. Geographic range of sipun- 

 culans is shown in Table 2. 



ECHIURA 



Echiurans are previously unrecorded from Enewetak or 

 the other Marshall Islands. However, the bifurcate-tipped 

 proboscis (sometimes up to a meter in length) of a bonellid 

 echiuran has been observed in the shallower waters of 

 Enewetak Lagoon extending from beneath attached coral 

 reef outcrops. Two specimens which appear to be of the 



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