Lutetiospongilla heili Richter and Wuttke, 1999

Pronzato, Roberto, Pisera, Andrzej & Manconi, Renata, 2017, Fossil freshwater sponges: Taxonomy, geographic distribution, and critical review, Acta Palaeontologica Polonica 62 (3), pp. 467-495 : 481-482

Lutetiospongilla heili Richter and Wuttke, 1999

Fig. 14 .

Type horizon: Eocene.

Type locality: Messel oil shale, Germany.

References: Richter and Wuttke 1999; Richter and Baszio 2000, 2001, 2009; Richter et al. 2017.

Description (emended from Richter and Wuttke 1999; Richter and Baszio 2000, 2001, 2009).—Encrusting growth on submerged plants (stems, roots). Gemmules in carpets at the sponge’s basal portion directly on the substrate. Megascleres oxeas, slender (300–350 × 8–12 μm), straight to slightly curved, with entire surface covered by small spines. Microscleres not surely identifiable. Gemmules (800–1000 μm in diameter) with evident lumen (300–400 μm in diameter) and gemmular theca (200–250 μm in thickness) with radially arranged gemmuloscleres surrounded by

→ Fig. 13. Palaeospongilla chubutensis Ott and Volkheimer, 1972 , Spongillida : Palaeospongillidae ; and Spongilla patagonica Volkmer-Ribeiro and Reitner, 1991 , Spongillida : Spongillidae ; Aptian, Lower Cretaceous, 16 km NNW of Cerro Condor, Patagonia Chubut River Valley, Argentina. Spicules, skeleton architecture and gemmules, paratype MABA 24748. A. Drawings of megascleres (a), gemmuloscleres (b), and microscleres (c). B. Possible transversal section of several gemmules. C. Skeleton multispicular fibres or gemmular cage. D. Megascleres and microscleres. E. Naked gemmules. F. Armed gemmule with radial gemmuloscleres and multispicular main fibre. G. Close up on the gemmular theca. H. Gemmule. I. Megascleres (a, b), microscleres of different dimensional classes (c, d). J. Gemmuloscleres. A–D, modified from Ott and Wolkheimer (1972), E–G, modified from Volkmer-Ribeiro and Reitner (1991 b), H–J, modified from Racek and Harrison (1975).

a dense spicular cover of tangential megascleres irregularly arranged. Gemmuloscleres of two types. Larger gemmuloscleres shaped from strongyles to strongyloxeas almost straight to curved, coarsely spiny with spines more densely arranged at the tips, and extremely variable in size and shape (80–220 × 12–20 μm, shaft thickness at the middle); tips usually slightly inflated with tubercles/spines. Smaller gemmuloscleres birotules short, straight, slender, squat or with very variable shape (40–60 × 5–10 μm, shaft thickness at the thinnest point) with weak spines. Spicule tips inflated with strong spines, frequently with an apical spine, quite often as imperfect discs.

Remarks.—According to the authors, the small gemmuloscleres of Lutetiospongilla heili are similar to those of the genus Radiospongilla , although in the former they generally have a significantly slimmer shaft and spiny tips from inflated to imperfect rotules. The large gemmuloscleres, strongyles, despite considerable differences in length, are strictly radially arranged and densely packed in the gemmular theca. In addition to this “normal” gemmular morph other gemmules occasionally apparently contain significantly smaller gemmuloscleres arranged in multiple layers. Much more difficult to recognize is the original arrangement of small gemmuloscleres because they are always internal and, usually, relatively disorganized. Broken gemmules always show more or less radial gemmuloscleres.

Richter and Baszio (2000, 2001, 2009) presented new images of L. heili . The spicular complement shown in these more recent papers seems to not match those reported in the original description. These authors compare L. heili to numerous extant genera in which the gemmuloscleres are also arranged radially in the gemmular theca (i.e., Radiospongilla , Heteromeyenia , Corvospongilla , Anheteromeyenia , Corvomeyenia , Dosilia , and Acalle ) concluding that Radiospongilla is the most similar to Lutetiospongilla . The taxon could be a mix of species and further studies are needed.

Figures

Fig. 14. Lutetiospongilla heili Richter and Wuttke, 1999, Spongillida: Spongillidae; Eocene, Messel oil shale, Germany. A. Holotype, SMF ME I 5143, carpet of closely bound gemmules with evident lumina and large radial gemmuloscleres. B. Single gemmular theca, firmly sessile on the surface of a woody plant, oblique view. Gemmular lumen (top right). C. Broken gemmule in the sediment with gemmular theca mainly formed of small more or less radially arranged gemmuloscleres. D. Broken-up lumen of a gemmule. Numerous mixed inner ends of large and small gemmuloscleres. E. Megasclere and large gemmuloscleres. F. Scattered sample with numerous huge gemmuloscleres.G. Megascleres originally finely spiny. Here, the pores are further apart and are narrower than in H. H. Gemmuloscleres from Messel with corrosion canals of original dense spines. SEM images. Modified from:A–D, Richter and Wuttke (1999); E, F, Richter and Baszio (2009); G, H, Richter and Baszio (2000).