The genus
Igernella Topasent, 1905 includes those dendroceratid
sponges characterised by an irregularly reticulate skeleton arising from a spongin plate and the presence of diactinal, triactinal, or tetractinal spiculoids. To date, two species of this genus had been described :
I. mirabilis Lévi from the Indo-Pacific and
I. notabilis (Duchassaing & Michelotti) from the central Atlantic. A re-examination of material previously assigned to the genera
Igernella and
Darwinella allowed us to detect the existence of a second species of
Igernella in the central Atlantic.
Igernella vansoesti sp. nov. is erected to include the specimens from the Cape Verde Islands assigned to
I. notabilis by Van Soest(1993), and one specimen from the Gulf of Mexico formerly recorded under the name
D. muelleri Schulze by de Laubznfels. The specimen described as
D. joyeuxi Topsent by Little (1963) probably belongs to this species as well. The new species is distinguishable from
I. notabilis by its massive growth habit -without conspicuous tubes-, a minutely conulose surface, small oscules, and a skeletal network, made of narrow primary
and secondary fibres, denser than that of
I. notabilis. There is an important amount of foreign material embedded in the mesohyl whereas it is scarce within the fibres or even absent. The absence of debris in the fibres of some species of
Igernella suggests a close relationship between this genus and other genera of the family Darwinellidae. This is in agreement with a recent proposal of moving the genus Igernella from the family Dictyodendrillidae to the family Darwinellidae on the basis of their chemical affinities