pseudovelumn.
/ˈs(j)uːdəʊˌviːləm/, U.S. /ˈsudoʊˌviləm/ Zoology. rare.
The velarium of a box jelly (cubozoan), which resembles the velum of a hydromedusa but lacks muscular and nervous tissue. Also: a similar structure around the swimming bell of some siphonophores.
ΚΠ
1881 Lankester in Encycl. Brit. XII. 555/2 The edge of its [sc. the medusa's] disc..is not provided with a velum (hence ‘Acraspeda’ of Gegenbaur), excepting the rudimentary velum of Aurelia and the well-developed vascular velum (pseudo-velum) of Charybdæa.
1968 J. Bouillon in M. Florkin & B. T. Scheer Chem. Zool. II. ii. i. 88 Order Cubomedusae... Umbrella margin simple, not scalloped, bending inward as a diaphragm or pseudovelum called ‘velarium.’
1978 Biol. Bull. 155 481 The circular muscles of the velum [of the siphonophore Hippodius] act together with those of the pseudovelum (the flexible margin of umbrella).
Derivatives
ˈpseudoˌvelar adj. rare.
ΚΠ
1890 Cent. Dict. Pseudovelar, vascular, as the velum of a scyphomedusan; having the character or quality of a pseudovelum.
1978 Biol. Bull. 155 487 Stimulation on the exumbrellar epithelium at St3 fails to excite the velar muscle but the pseudovelar fibers contract.
This entry has been updated (OED Third Edition, September 2007; most recently modified version published online March 2022).
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n.1881