rhombogenn.
/ˈrɒmbədʒ(ə)n/, U.S. /ˈrɑmbədʒ(ə)n/ Zoology.
In certain mesozoans: a sexual adult form which gives rise to a free-living infusoriform larva. Cf. nematogen n. 1.
ΘΚΠ
the world > animals > invertebrates > protozoa > class Infusoria > [noun] > member of > form which produces infusoriform embryos
rhombogen1880
1880 F. M. Balfour Treat. Compar. Embryol. I. iv. 108 It originates in the shorter and thicker individuals of Dicyema; which have been called Rhombogens.
1888 G. Rolleston & W. H. Jackson Forms Animal Life (ed. 2) 815 The Rhombogen and secondary Nematogen are successive phases in the life-history of one and the same individual.
1987 M. S. Laverack & J. Dando Lect. Notes Invertebr. Zool. (ed. 3) vi. 42 The oval larva..escapes from the vermiform parent or rhombogen into the host urine and then into the sea.
1998 L. Margulis & K. V. Schwartz Five Kingdoms (ed. 3) iii. 232/1 Stages in the rhombozoan life cycle include rhombogen, nematogen, vermiform larvae, and infusoriform larvae.
Derivatives
rhomboˈgenic adj. now rare
ΘΚΠ
the world > animals > invertebrates > protozoa > class Infusoria > [adjective] > of form which produces infusoriform embryos
rhombogenic1882
1882 C. O. Whitman Contrib. Embryol., Life-hist. & Classif. Dicyemids 39 He failed to recognize that their appearance marks the vanishing point of the Rhombogenic phase of life.
1885 Encycl. Brit. XVIII. 259/1 The embryos are of two kinds, nematogenic or vermiform, and rhombogenic or infusiform.
This entry has been updated (OED Third Edition, June 2010; most recently modified version published online March 2022).
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n.1880