Cretaceous sponges from the Campanian of Misburg and Höver
Siphonia Goldfuss 1833

Locality. Alemannia, Höver
Height: 350 mm

Siphonia (Pachycalymma) subglobosa

Schrammen, 1901

Siphonia species appear to be quite rare in the Upper Campanian strata of Misburg, but are more common in the Lower Campanian of Höver. The Lower Campanian representatives tend to become very tall (often more than 300 mm).

The specimen of Pachycalymma subglobosa shown here has some cortex developped in its basal parts. The paragaster is sourounded by a set of distinct, radial furrows. The ostia are relatively large (1 to 3 mm) and have jagged outlines.

Locality. Alemannia, Höver
Height: 200 mm

The second example of Pachycalymma subglobosa shows the typical, large and jagged, inhalent pores.

The spiculation of Siphonia consists of zygosed tetraclone desmas with smooth arms. The branching of the desma arms of Siphonia species begins closer to the center of the tetraclone, compared to those of Phymatella and related genera (Aulaxinia, Callopegma, Turonia, Craterella, Kalpinella and Paraspelaeum), and the resulting skeletal meshwork thus shows some subtle differences. In particular, Siphonia does not show the syzygial nodes (nodes formed by the union of arms of neighboring desmas) characteristic for the other genera. Dichotriaenes may be present as dermal scleres.

Locality. Alemannia, Höver
Height: 250 mm

Siphonia tubulosa

Roemer, 1840

The specimen shown here is thought to be equivalent to Siphonia tubulosa (Scyphia tubulosa of Roemer 1840). It differs from Pachycalymma by its club-shaped form and irregular sculpturing.

Locality. Alemannia, Höver
Locality. Alemannia, Höver

The following photomicrographs show typical tetraclones and one dermal dichotriaene of Siphonia tubulosa. Notice the onset of branching close to the center of the tetraclones, and compare for instance with Callopegma acaule!

Some small Siphonia species are difficult to distinguish macroscopically from certain small forms of Phymatella, particularly Phymatella sphaeroides. This is due to similarities in the skeletal structure. The main differences are in the internal canalization, which is invisible unless the specimen is destroyed. However, Siphonia lacks the constrictions near the base of the sponge body, which are typical for Phymatella, and there are subtle differences in the skeletal structure.

Considerable "taxonomic chaos" exists for Siphonia and the related genera Jerea, Thecosiphonia, and Polyjerea. The problem of identifying and naming a particular specimen is further aggravated by the high morphological variability of Siphonia and the other species. E.g., many juvenile forms of Siphonia have no paragaster, but instead a group of oscula at their apex, while adult individuals tend to have a deep, tubular paragaster.