Family DESMACELLIDAE Ridley & Dendy, 1886

Museums

Museum list

Regional Maps

Family DESMACELLIDAE Ridley & Dendy, 1886

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)

Introduction

Desmacellidae Ridley & Dendy, 1886 is a family of varied forms, including encrusting, massive, cup-shaped, fan-shaped and branching sponges. Their megascleres are usually styles (Hooper & Wiedenmayer 1994: figs 17, 18), but sometimes also include oxeas or strongyles (Hooper & Wiedenmayer 1994: figs 5, 6). Spicules are typically enclosed within plumose, reticulate, halichondroid-reticulate or compressed axial fibres. Microscleres are diverse, always consisting of sigmas (Hooper & Wiedenmayer 1994: figs 79–81), and often including microxeas of several sizes (Hooper & Wiedenmayer 1994: fig. 105), raphides in bundles or individually (Hooper & Wiedenmayer 1994: figs 109, 110), toxas (Hooper & Wiedenmayer 1994: fig. 89), microstrongyles and spheres.

Members of this poecilosclerid family are widely distributed in the world's oceans, from shallow waters down to at least 2165 m (Hartman 1982). There are sixteen nominal genera included in the revised Desmacellidae, of which only seven are currently valid, although of these recognised genera Sigmaxia is probably a synonym of Sigmaxinella and Kerasemna and Microtylostylifera are still not well known. Six of the genera are represented by species in the Australian fauna, particularly Biemna which is unusually common in this region. The hypercalcified Merlia is also present in the fauna (A. Ayling, pers. comm.), although records are not yet published.

As used by Hooper (1984), Desmacellidae includes genera with condensed axial skeletons, showing obvious affinities to 'axinellid' groups (Sigmaxinella, Sigmaxinyssa, and Sigmaxia), and those with reticulate, plumo-reticulate or halichondroid skeletons traditionally associated with the Poecilosclerida (Desmacella, Biemna, Neofibularia and Kerasemna). In contrast, Van Soest (1984a) retained skeletal architecture as an important diagnostic character, differentiating Sigmaxinellidae from Biemnidae. Later, he accepted the name Desmacellidae (Van Soest 1987), but also included in the latter group Hamacantha and Pozziella (included here with Hamacanthidae). Subsequent reorganisation of the Axinellida (e.g. Van Soest et al. (1990) and Hooper et al. (1992)) discounting the importance of axial condensation of the skeleton as a primary apomorphy, indicates that the family should be included with the Poecilosclerida.

The hypercalcified 'sclerosponge' Merlia is included here on the basis that its commata are homologous with those of Biemna and Neofibularia, but another interpretation is offered by Van Soest (1984a). He notes that the presence of commata microscleres in the hypercalcified 'sclerosponge' Merlia is a characteristic shared with the Desmacellidae genus Biemna, and that clavidiscs found in Merlia may be of sigmoid (rather than cheloid) origin. He suggests further that these clavidiscs of Merlia may be related to those of Hamacantha (with diancistras) and Poziella (with cyrtancistras; included here in the family Hamacanthidae), whereby the clavidiscs of Merlia may be merely compound diancistras, thus supporting his proposal to combine the families Desmacellidae and Hamacanthidae. However, these families are retained separately here on a tentative basis since there is still disagreement as to the sigmoid or cheloid origin of diancistras (Lévi, in Brien et al. 1973; Fromont & Bergquist 1990 and Vacelet & Uriz 1991).

Recent revisions include Hooper (1984), Van Soest (1984b), Bergquist & Fromont (1988) and Hooper et al. (1991). Wiedenmayer (1977) gives a resumé, and genera are differentiated by Hartman (1982). Two other names are included in synonymy with Desmacellidae: Biemnidae Hentschel, 1923 and Sigmaxinellidae Lévi, 1955.

Diagnosis

Encrusting, massive, cup-shaped, fan-shaped and branching sponges. Megascleres are usually styles, occasionally oxeas or strongyles. Spicules are typically enclosed within plumose, reticulate, halichondroid-reticulate or compressed axial fibres. Microscleres are diverse, usually consisting of sigmas (one genus excepted), and often including microxeas of several sizes, raphides in trichodragmata or occurring singly, commata, some of which may be microspined or rugose. Species belonging to this family may occur in all oceans and at all depths.

ID Keys

KEY TO GENERA
(1) Two widely divergent sizes of subtylostyles, the smaller may be considered microscleres ---Microtylostylifer
Subtylostyles may be present, but no distinct microsubtylostyles --------------------------------------------------------- 2

(2) Fistular sponge with parchment-like surface enclosing a bladder-like body; styles and trichodragmas, no sigmas -----------------------------------------------------------------------------------------------------------------------Dragmatella
Sigmas present ------------------------------------------------------------------------------------------------------------------- 3

(3) Skeleton strongly compressed axially --------------------------------------------------------------------- Sigmaxinella
No axial condensation; skeletons plumose, plumo-reticulate, reticulate or vaguely halichondrioid -------------------- 4

(4) Megascleres tylostyles, occasionally styles; microscleres limited to sigmas and raphides ----------- Desmacella
Megascleres (subtylo-)styles, oxeas or strongyles; in addition to sigmas and raphides there are microxeas and often also commata; frequently producing dermatitis ----------------------------------------------------------------------- 5

(5) Ectosomal skeleton arranged brush-like; choanosomal skeletons mostly plumose or plumoreticulated --- Biemna
Ectosomal skeletons tangential, choanosomal skeletons neatly reticulated, spongin mostly abundant ------------------------------------------------------------------------------------------------------------------------- Neofibularia