Family IOTROCHOTIDAE Dendy, 1922

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Introduction

The recognition of Dendy's (1922) largely ignored section Iotrochoteae at the family level unites genera possessing the peculiar birotulas, previously assigned to a variety of families (e.g. Desmacididae (Iotrochota), Coelosphaeridae (Amphiastrella), Myxillidae (Iotrochota, Iotroata), Hymedesmiidae (Hymetrochota), and Microcionidae (Rotuloplocamia)). The family is represented in most areas of the world in shallow as well as deeper waters. Eleven nominal genera, six of which are considered valid: Amphiastrella, Hymetrochota, Iotroata, Iotrochopsamma, Iotrochota and Rotuloplocamia.

Diagnosis

Encrusting, massive, fistular, ramose or flabellate sponges; ectosomal skeleton variously consisting of perpendicular or tangentially arranged tornotes or absent; many genera demonstrate a lack of differentiation of megascleres. Choanosomal skeleton reticulate or hymedesmioid. Choanosomal megascleres styles, strongyles, or tylotes, smooth or acanthose. Microscleres birotulas, occasionally also anchorate isochelae and sigmas.

ID Keys

KEY TO GENERA
(1) No megascleres; the skeleton is a reticulation of sand grains ----------------------------------- Iotrochopsamma
At least one category of megascleres ----------------------------------------------------------------------------------------- 2

(2) Fistular growth form with parchment-like surface made up of intercrossing strongylote or tylote spicules. Choanosomal skeleton vestigial ----------------------------------------------------------------------------- Amphiastrella
Choanosomal skeleton elaborate, reticulated, plocamiid or hymedesmioid ---------------------------------------------- 3

(3) Acanthose megascleres present ------------------------------------------------------------------------------------------- 4
Acanthose megascleres absent ------------------------------------------------------------------------------------------------ 6

(4) Among the acanthose megascleres there are acanthose strongyles and tylotes; skeleton arrangement is plocamiid ----------------------------------------------------------------------------------------------------- Rotuloplocamia
No acanthostrongyles or -tylotes; skeleton hymedesmioid or reticulate ------------------------------------------------ 5

(5) Thin encrustations. Skeleton hymedesmioid (i.e., with acanthostyles erect on the substrate, points outwards, with shorter acanthostyles in groups at the base -------------------------------------------------------- Hymetrochota
Massive or lamellar. Skeleton reticulate, no smaller echinating acanthostyles -------------------------------- Iotroata

(6) Rectangular reticulation of polyspicular tracts; differentiation in shorter/fatter and longer/thinner spicules which may be either styles\or strongyles or both, but these are not functionally localized ---------------------- Iotrochota
Reticulation of single spicules or paucispicular tracts; differentiation into ectosomal tornotes and choanosomal styles ----------------------------------------------------------------------------------------------------------------------------- Iotroata

Diagnosis References

van Soest, R.W.M. 2002. Family Iotrochotidae Dendy, 1922. pp. 594-601 in Hooper, J.N.A. & van Soest, R.W.M. (eds). Systema Porifera: A guide to the classification of sponges. New York : Kluwer Academic/Plenum Publishers Vol. 1. [594]

General References

van Soest, R.W.M. 2002. Family Iotrochotidae Dendy, 1922. pp. 594-601 in Hooper, J.N.A. & van Soest, R.W.M. (eds). Systema Porifera: A guide to the classification of sponges. New York : Kluwer Academic/Plenum Publishers Vol. 1.

History of changes