radiolaria - rads_cat - Actissa <title>radiolaria - rads_cat - Actissa


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Higher levels: rads_cat -> A -> Actissa
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not figuredActissa discoides Haeckel 1887

not figuredActissa ellipsoides Haeckel 1887

not figuredActissa larcoides Haeckel 1887

not figuredActissa lenticularis Haeckel 1887

not figuredActissa phacoides Haeckel 1887

Actissa princeps Haeckel 1887

not figuredActissa prototypus Haeckel 1887

not figuredActissa prunoides Haeckel 1887

not figuredActissa radiata Haeckel 1887


Citation: Actissa Haeckel 1887
Rank: genus
Type species: Actissa princeps Haeckel 1887 [designated by Brandt,1902, p.81]
Described on page(s) : 12
Family (traditional): not-known

Current identification:

Original Description

Thalassicollida with simple spherical nucleus, without any alveoli (either within or outside the central capsule).



From the Greek actissa = radiant"

Extra details from original publication
The genus Actissa is the most simple and typical form of all Radiolaria, and may be regarded as the common ancestral form of the whole class. The spherical body is composed of a simple spherical capsule and a concentric spherical calymma or jelly envelope. Neither the former nor the latter contains alveoli. The central capsule possesses a strong membrane perforated by small pores, and contains in the intracapsular sarcode numerous small pellucid vacuoles, and in its middle a simple, concentric, spherical nucleus (often with some nucleoli); sometimes also one or more oil globules. The extracapsularium forms a soft, voluminous, structureless calymma or enveloping jelly sphere, perforated by the numberless, fine pseudopodia, which radiate outwards from the matrix or the thin granulated sarcode layer, surrounding the capsule. Often (but not constantly) xanthellæ or yellow cells are scattered in it. Actissa differs from the following skeletonless genera in the absence of all alveoli; it has neither intracapsular alveoli (like Thalassolampe) nor extracapsular alveoli (like Thalassicolla). The first observed species of this genus is that which I found in 1866 at the Canary Islands, Actissa prototypus; the second is that which Hertwig accurately described in 1879, from the Mediterranean (Messina), Actissa primordialis; the third I observed in 1881 at Ceylon, frequent and sporiparous, Actissa princeps. A fourth species (Actissa radiata) exhibited a distinct radial segmentation of the capsule contents. These four species are quite spherical. Six other species, occurring in different preparations from the Challenger, are distinguished by modifications of the spherical capsule form and may represent three different subgenera (or, perhaps better, genera?) - Actiprunum ellipsoidal, Actidiscus lenticular, Actilarcus lentelliptical; perhaps these are the ancestral forms of the three sections: Prunoidea, Discoidea, Larcoidea. [1041:12]

[In accordance with ICZN (1961) art.23 (e) (i), this genus should have been called Procyttarium Haeckel, 1879, since Haeckel, 1887a treats Procyttarium as a subgenus of Actissa, and the other subgenric names used are of a later date than 1879.]
Sub-genera described:

Editors' Notes


Haeckel, E (1887a). Report on the Radiolaria collected by H.M.S. Challenger during the years 1873-1876. Report on the Scientific Results of the Voyage of H.M.S. Challenger during the years 1873-1876. 18: 1-1803. gs O


Actissa compiled by the radiolaria@mikrotax project team viewed: 7-2-2023

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