Alomasoma nordpacificum Zenkevitch, 1958

Biseswar, Ramlall, 2010, Report on deep-sea bonelliids (Echiura) from the East Equatorial Atlantic Ocean, Zoosystema 32 (1), pp. 139-154 : 142-143

publication ID

https://doi.org/ 10.5252/z2010n1a7

DOI

https://doi.org/10.5281/zenodo.4559918

persistent identifier

https://treatment.plazi.org/id/137387F1-A079-9350-FF02-FA52FE583D43

treatment provided by

Felipe

scientific name

Alomasoma nordpacificum Zenkevitch, 1958
status

 

Alomasoma nordpacificum Zenkevitch, 1958 View in CoL

( Fig. 1 View FIG C-E)

MATERIAL EXAMINED. — East Equatorial Atlantic Ocean. GulfofGuinea,BIOZAIRE3,CP13, stnZB-C, 7°39.7530’S, 10°1.2916’E, 3991 m, 23.XII.2003, 2 ♀♀.

DESCRIPTION

Colour of trunk of preserved specimens is beige. Probosces missing in both specimens.Posterior end of trunk damaged in one female.In other specimen trunk is pear-shaped ( Fig. 1C View FIG ), 35 mm long and 17 mm across broadest part.Integument is thick and opaque in anterior half of trunk but thin and transparent in posterior half. Round to oval papillae closely arranged only on anterior half of trunk, posterior half is smooth and devoid of papillae. Single genital pore is located about 5 mm away from anterior end of trunk ( Fig. 1C View FIG ). Ventral setae absent.

Gonoducts one pair ( Fig. 1D View FIG ), small, spherical, unite proximally beneath nerve cord and open to exterior by a single genital pore. Gonostomes set on long stalks, basal in position. Gonostomal lips petaloid ( Fig. 1D View FIG ). Only foregut is intact, rest of intestine is missing including blood system. Pharynx is bulbous, clearly demarcated from oesophagus ( Fig. 1E View FIG ). Gut contents moulded into oval faecal pellets.Anal vesicles are branching tubules terminating in ciliated funnels and opening into rectum.

REMARKS

The genus Alomasoma is distinguished in possessing two gonoducts which unite proximally to form a common duct which opens to the exterior by a single genital pore. The gonostomes are basal and set on long stalks. Anal vesicles are branching tubules terminating in ciliated funnels. The genus Alomasoma is closely related to the genus Amalosoma Fisher, 1948 . In the latter genus the two gonoducts open to the exterior separately. Furthermore, a specialized genital slit is present anterior to the genital pore in Amalosoma but absent in Alomasoma .

The species A. nordpacificum has been described by DattaGupta (1981) and Biseswar (2005) from the North Atlantic. The discovery of this species in the East Equatorial Atlantic Ocean considerably extends its range of distribution.

Kingdom

Animalia

Phylum

Annelida

Class

Polychaeta

Order

Echiuroidea

Family

Bonelliidae

Genus

Alomasoma

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