Family TETHYIDAE Gray, 1867

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Family TETHYIDAE Gray, 1867

Compiler and date details

2010 - John N.A. Hooper, Queensland Museum, Brisbane, Queensland, Australia; Felix Wiedenmayer (1994), Naturhistorisches Museum Basel, Basel, Switzerland; updated by John N.A. Hooper (1999)

Diagnosis

Body shape typically globose (spherical, hemispherical, ovoid), but also sometimes irregularly massive, lobate or encrusting. Sometimes with a basal stalk. The surface is verrucose with tubercles, typically hispid and frequently flattened. Oscules rarely visible, generally apical, and the pores are in grooves between tubercles. A cortex may be well-developed and sharply distinct from the choanosome, but sometimes poorly developed or indistinct (pseudocortex). The skeleton structure is constructed by stylote (or modified stylote) megascleres, usually in radiate tracts (but in some genera in parallel tracts running from the substrate to the tubercles). The main bundles may branch and sometimes are loose in confused tracts, or crossed by thinner transverse bundles. Interstitial megascleres may also be scattered between the tracts. Spicules generally include stylote megascleres and two types of asters: megasters and micrasters. Stylote megascleres are frequently strongyloxeas (fusiform styles), but may be also styles, subtylostyles, tylostyles or anisostrongyles. In one case (Oxytethya) the megascleres are oxeas. Megasters are spherasters, oxyspherasters and oxyasters. Micrasters are euasters of the tylaster, strongylaster and oxyaster type. Exceptionally one category of aster (megasters or micrasters) may be lacking, a presumed secondary loss. Other spicules occasionally found are polyrhabds, microstrongyles, exotyles and spheres. Reproduction may be oviparous with a parenchymella larvae, or asexual by external (and sometimes internal) buds.

ID Keys

KEY TO GENERA
(1) Without basal stalk (or with stalk not exceeding half of the body diameter) ----------------------------------------- 2
With basal stalk longer than half of the body diameter ---------------------------------------------------------------------- 8

(2) With a well developed and distinct cortex, body spherical or subspherical ------------------------------------------- 3
With a little developed or indistinct cortex, irregularly massive or encrusting body ------------------------------------- 4

(3) Megasters spherasters or oxyspherasters, rather homogenous in size not exceeding 180um in diameter ----------------------------------------------------------------------------------------------------------------------------- Tethya
Megasters oxyasters, very heterogeneous in size even exceeding 180um in diameter ----------------- Tethyastra
Without megasters, megascleres oxeas ------------------------------------------------------------------------ Oxytethya

(4) Megascleres styles, subtylostyles or strongyles ------------------------------------------------------------------------ 5
Megascleres tylostyles ------------------------------------------------------------------------------------------- Tethytimea

(5) Megascleres in radiate tracts proximally crossed by thinner megascleres -------------------------- Nucleotethya
Megascleres in radiate ascending tracts, branching and anastomosing --------------------------------------------------- 6
Megascleres in parallel ascending tracts --------------------------------------------------------------------------------------- 7

(6) Megasters anthasters --------------------------------------------------------------------------------------- Anthotethya
Megasters spherasters or oxyspherasters --------------------------------------------------------------------- Tectitethya
Without megasters, megasclere tracts partially loosened or confused ------------------------------------- Laxotethya

(7) With megasclere tracts arising from a central sediment core, proximally crossed by thinner megascleres, with
a winding cylindrical body ------------------------------------------------------------------------------------------- Columnitis
With megasclere tracts arising from a sediment basis, discoid body --------------------------------------- Xenospongia
With giant megasters, thick encrusting or massive body ------------------------------------------------------ Stellitethya

(8) With stalk about the same length of body diameter --------------------------------------------------- Burtonitethya
With stalk about two to four times the body diameter ------------------------------------------------------- Halicometes
With stalk about eight times the body diameter ------------------------------------------------------------ Tethycometes