Family HYALONEMATIDAE Gray, 1857

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Introduction

Hyalonematidae Gray, 1857 are sponges with spheroid or ovoid bodies, although the actual shape can be very variable. Tufts of long basal spicules anchor the sponges in soft sediments. Basal spicules have a terminal 'anchor', consisting of an inverted-conical swelling bearing a circle of several short teeth. These basal spicules (Hooper & Wiedenmayer 1994: fig. 193) are bundled compactly and twisted dextrally, forming a single basal tuft extending into the sponge body and there forming a compact axial columella. The apical end of these spicules may give rise, at the upper pole of body, to a small projection called the gastral cone. Exhalant canals open on top of the body around the columella or gastral cone and are sharply offset from the inhalant surface by the oscular margin. Four separate exhalant canals may open around the columella, or the entire exhalant region may be either inwardly depressed or outwardly bulging to form a 'gastral' cavity, sometimes covered by a lattice-like sieve plate. Neither uncinate spicules nor scepters are present. Marginal prostals are pinular rhabdodiactines (i.e. diactinal with the distal end spined, as in Fig. 194); pleural prostals are smooth diactines. Choanosomal supporting spicules are mostly rhabdodiactines, often occurring in association with macrohexactines or macropentactines (Hooper & Wiedenmayer 1994: figs 194, 195, 200, 201).

The family occurs in abyssal waters to a depth of at least 5900 m. Species extend upwards into bathyal waters to at least 200 m and are worldwide in distribution (Hartman 1982). Many nominal genera are included in the family, but probably only four are valid. Only Hyalonema, and three of its subgenera, have been reported so far for the Australian fauna.

Reviews of the family are available in Schulze (1904); Ijima (1927; with discussion, key); and Hartman (1982).

Diagnosis

Body varies strongly: oval, cup-like or spindle-like (consists of two opposite cones), lophophytose, with or without atrial cavity. Basalia are located in a single tuft, contain spicules with more than two teeth (usually 4–8), other prostalia are represented by diactines, usually with pinular distal ray. Choanosomal skeleton consists predominately of diactines. Hexactines, ambuncinates and rarely uncinates are found in various combinations with diactines. Dermalia and atrialia are pinular pentactines, rarely hexactines. Hypodermal and hypoatrial skeleton consists of pentactines. Amphidiscs are various, usually they are represented by three kinds. Microhexactines and micropentactines usually prevail upon all their derivatives up to monactines.

ID Keys

KEY TO GENERA AND SUBGENERA

(1) Macramphidiscs or large mesamphidiscs have serrated teeth edges ................... Hyalonema (Prionema)
All macramphidiscs have smooth teeth edges ................................................................................ 2
(2) Dermal pinular ray is thickest at base, tapering towards the end ..................................................... 3
Dermal pinular ray is spindle-like (rarely even) with outer end represented by an apical cone (rarely conical) .... 13
(3) Macramphidiscs have umbels longer than broad ......................................................................... 4
Macramphidiscs have umbels broader than long or as broad as long ...................................................... 6
(4) Dermal pinular ray with unusually long spines .................................... Hyalonema (Thamnonemiella)
Dermal pinular ray short-spiny or moderately long-spiny .................................................................... 5
(5) Dermal pinular ray is even with rounded or conically pointed outer end; basalia are anchorate spicules with pileate, serrated discs .......................................... ..................................................... Platella
Dermal pinular ray is usually whip-like; basalia are four-toothed anchors ................Hyalonema (Leptonema)
(6) Dermal pinular ray with unusually long spines ................ ..................... Hyalonema (Phialonemiella)
Dermal pinular ray short-spiny or moderately long-spiny ................................................................... 7
(7) With paradiscs among micramphidiscs ............................................... Hyalonema (Paradisconema)
Without paradiscs among micramphidiscs ...................................................................................... 8
(8) Ambuncinates absent ........................................................................................................ 9
Ambuncinates present ........................................................................................................... 10
(9) Sieve-plate absent ......................................................................... Hyalonema (Cyliconema)
Sieve-plate present, basalia are situated in a broad, loose, untwisted tuft ............................. Charalonema
(10) Dermal pinular ray moderately long-spiny, conical or spindle-like in general shape (with or without sieve-plate)
..................................................................................................... Hyalonema (Pteronema)
Dermal pinular ray short-spiny often whip-like in general shape ........................................................... 11
(11) Prostalia lateralia are gathered in tufts on conical prominances of dermal surface; atrial surface is divided by septas into four parts ......................................................................................... Composocalyx
Dermal surface has no conical prominances and tufts of prostalia lateralia .............................................. 12
(12) The sieve-plate when present has open small meshes uniformly distributed .... Hyalonema (Coscinonema)
The sieve-plate has open meshes assembled in groups separated by imperforate tracts ........................... .......................................................................................................Hyalonema (Hyalonema)
(13) With uncinates ............................................................................... Hyalonema (Onconema)
Without uncinates ................................................................................................................ 14
(14) Body composed of two opposite cones ............................................................... Lophophysema
Body is bell-like or oval .......................................................................................................... 15
(15) Most macramphidiscs are ovoid with umbels 1/3–1/2 long as the length of the whole spicule .......................................................................................................... Hyalonema (Oonema)
Macramphidiscs have umbels narrower or broader than long, their umbels are about 1/4–1/3 long as the length of the whole spicule ...............................................................................Hyalonema (Corynonema)

Diagnosis References

Tabachnick, K. & Menshenina, L. L. 2002. Family Hyalonematidae Gray, 1857. pp. 1232-1263 in Hooper, J.N.A. & Soest, R.W.M. Van (eds). Systema Porifera. A guide to the classification of sponges. New York : Kluwer Academic/Plenum Publishers Vol. 2. [1232]

General References

Hartman, W.D. 1982. Porifera. pp. 640-666 in Parker, S.P. (ed.). Synopsis and Classification of Living Organisms. New York : McGraw-Hill Vol. 1.

Ijima, I. 1927. The Hexactinellida of the Siboga Expedition. 1-383 26 pls in Weber, M.W.C. (ed.). Siboga-Expeditie, livr. 106, monogr. 6. Leiden : J.E. Brill.

Schulze, F.E. 1904. Hexactinellida. In Chun, C. (ed.) Wissenschaftliche Ergebnisse der Deutschen Tiefsee-Expedition auf dem Dampfer 'Valdivia' 1898–1899. Vol. 4 266 pp. (text) pls 1–52 (atlas).

Tabachnick, K. & Menshenina, L. L. 2002. Family Hyalonematidae Gray, 1857. pp. 1232-1263 in Hooper, J.N.A. & Soest, R.W.M. Van (eds). Systema Porifera. A guide to the classification of sponges. New York : Kluwer Academic/Plenum Publishers Vol. 2.

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