Cretaceous sponges from the Campanian of Misburg and Höver

 

Aphrocallistes alveolites

(Roemer) 1841

Figure 1 - Aphrocallistes alveolites.
Alemannia, Höver, senonensis zone.


Figure 2 - Aphrocallistes alveolites.
Teutonia North, Misburg, vulgaris/stolleyi zone.


Figure 3 - Aphrocallistes alveolites.
Teutonia South, Misburg, conica/mucronata zone.


Synonyms:

Scyphia alveolites Roemer 1841

 

Occurence:

Alemannia, Höver, Lower Campanian (senonensis zone). Moderately common.

Teutonia, Misburg, Upper Campanian. Moderately common.

 

Aphrocallistes alveolites forms subhorizontal branching tube systems, with vertical chimneys whose terminal apertures are covered by sieve plates. The basal tubes are 10 to 20 mm in diameter, the chimneys may be up to 50 mm in diameter. Presently available material suggests that there is generally one central chimney which sends out several radial tubes, each of which has its own secondary chimney.

The tube walls are approximately 1.5 mm thick and are perforated by radial channels (diarhyses), giving rise to the very regular, almost honeycomb-like pore structure which makes Aphrocallistes species easily recognizable.

Figures 1, 2 and 3 show fragmental specimens consisting of subhorizontal, branching tubes with closed, finger-like terminations and chimneys. The chimneys have wide oscules covered with characteristic sieve plates whose structure resembles that of the tube walls, but the pore sizes are distinctly larger.

The finger-like ends of the subhorizontal tube sections are rounded, closed, and often point downward and may grade into root-like supports.

Figure 4 - Aphrocallistes alveolites. Photomicrograph.
Wall structure.


Figure 5 - Aphrocallistes alveolites. Photomicrograph.
Inhalent pore with web.


Figure 6 - Aphrocallistes alveolites. Photomicrograph.
Internal view of diarhyses.


Figure 7 - Aphrocallistes alveolites. Photomicrograph.
Detail of hexactine skeleton.


Figure 8 - Aphrocallistes alveolites. Photomicrograph.
External face of sieve plate.

Figures 4 through 8 are photomicrographs of etched specimens of Aphrocallistes alveolites.

The tubular canals (diarhyses), which are open to both sides, are more or less hexagonal to circular in cross-section. The canal walls consist of meshworks made up from fused hexactines, while the canal endings are fortified by heavily silica-mantled scleres.

These walls are formed by fused hexactines, which are slightly flattened along the "octahedral direction of the cubic coordinate system", and the hexactine arms are connected in a manner such that mostly triangular mesh outlines are produced. The pore walls consist of only a single layer of interconnected hexactines. In some parts, the axial canals of the hexactines are clearly visible as black lines caused by (bacterially precipitated ?) pyrite fillings (Figures 5 and 6).

Near the outer (dermal) surface, the pore channels sometimes show very delicate, web-like structures. Perhaps all pore openings had such webs, but they are generally not preserved (Figure 5).

Figure 8 shows the structure of the sieve plate.


 

Aphrocallistes cylindrodactylus

Schrammen 1912

Figure 1 - Aphrocallistes cylindrodactylus.
Alemannia, Höver, senonensis zone.


Figure 2 - Aphrocallistes cylindrodactylus.
Teutonia North, Misburg, stobaei/basiplana zone.


Figure 3 - Aphrocallistes cylindrodactylus.
Alemannia, Höver, senonensis zone.

Synonyms:

none

 

Occurence:

Alemannia, Höver, Lower Campanian (senonensis zone). Rare.

Teutonia, Misburg, Upper Campanian (stobaei zone). Rare.

 

Individuals of Aphrocallistes cylindrodactylus consist of a central atrium with a wide osculum. The atrium is lined by a kettle- or pouch-like sieve plate. The outer wall has numeros finger-like appendices and protrusions.

The external wall of Aphrocallistes cylindrodactylus is approximately 1 mm thick and is perforated by radial channels (diarhyses), very similar to Aphrocallistes alveolites.

Figures 1 to 3 show three more or less complete individuals of Aphrocallistes cylindrodactylus.

The finger-like protrusions have rounded terminations, except for those by which the sponge is attached to some substrate (e.g. the elongated basal protrusion visible in Figure 2).


 

Aphrocallistes lobatus

Schrammen 1912

Figure 1 - Aphrocallistes lobatus.
Alemannia, Höver, senonensis zone.


Figure 2 - Aphrocallistes lobatus.
Alemannia, Höver, senonensis zone.


Synonyms:

none

 

Occurence:

Alemannia, Höver, Lower Campanian (senonensis zone). Rare.

Ahlten, Upper Campanian. Rare.

 

Aphrocallistes lobatus was described by Schrammen (1912) as a new species from Ahlten (upper Campanian), although he noted already similarities with the extant species Aphrocallistes vastus.

The external wall of Aphrocallistes lobatus is perforated by radial channels (diarhyses), similar to the other fossil Aphrocallistes species. However, the skeletal structure is more robust, with a thicker wall (1.5 to 2 mm) and somewhat wider channel and pore apertures.

Figures 1 and 2 show large fragments, suggesting that Aphrocallistes lobatus formed larger sponge bodies. However, the general body plan of this species is not yet clear.

Specimen 1 (Figure 1) consists of a multiply folded wall, which forms anastomosed ribs, several centimeters high and with a constant width of approximately 7 to 8 mm. The ribs are flush, i.e. bounded by a common enveloping surface, and the rib edges thus formed are planar or slightly depressed. They form right angles with the side walls of the ribs. It appears that these fold edges are equivalents of terminal sieve plates of the other Aphrocallistes species, but the pore structure looks very similar to that of the side walls and needs microscopic investigation.

Specimen 2 (Figure 2) consists of similar ribs as specimen 1, but here the ribs apperar to be arranged radially around a central axis, suggesting yet another body plan.


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