Ephydatia chileana Pisera and Sáez, 2003

Pronzato, Roberto, Pisera, Andrzej & Manconi, Renata, 2017, Fossil freshwater sponges: Taxonomy, geographic distribution, and critical review, Acta Palaeontologica Polonica 62 (3), pp. 467-495 : 486-487

Ephydatia chileana Pisera and Sáez, 2003

Fig. 20 .

Type horizon: Late Miocene.

A 100 μm B 20 μm C

20 μm D 10 μm E 200 μm

Type locality: Quillagua Formation , Atacama region, Chile. References: Pisera and Sáez 2003 .

Description (emended from Pisera and Sáez 2003).—Three intact gemmules and many loose megascleres and gemmuloscleres preserved in a diatomite. No entire sponge bodies. Megascleres slightly curved, smooth oxeas (240–350 × 8–15 μm). Gemmules spherical to flattened (237–250 μm in diameter). Gemmuloscleres birotules (39–45 μm in length), with spiny shaft (5.5–7.2 μm in thickness) armed by a variable number (4–11) of strong, long conical spines of variable length. Rotules (usually 24.8–27.0 μm in diameter) with irregular margins, often deeply incised, and the resulting teeth (16 to 20–21 spines) not in the same plane vary greatly in length (ca. 11.0 μm at the longest); rotules upper surface, clear, flat, with a button-like central convexity (umbonate rotule). In one gemmule, many aberrant rotules bear a swelling in the middle of the shaft, along with rotules of normal morphology. Spines reduced to small tubercles on a bulbous-like termination of rotules and/or less numerous and irregularly developed.

Remarks.—The investigated material resembles the Recent cosmopolitan species Ephydatia fluviatilis but differs from it in having smaller diameters of gemmules, longer and thicker shafts of the gemmuloscleres, and larger diameter of rotules. E. chileana also has many long, conical spines on the gemmuloscleres’ shaft. The upper surface of the rotule is smooth in the investigated material, whereas in E. fluviatilis , it is often spiny to various degrees. Megascleres are of very similar size and smooth in E. chileana , whereas they are often microspinose in E. fluviatilis .

Figures

Fig. 20. Ephydatia chileana Pisera and Sáez, 2003, Spongillida: Spongillidae, ZPAL Pf12; late Miocene, Quillagua Formation, Atacama region, Chile. A. Gemmule (cross-section). B. Gemmular theca with radial gemmuloscleres bearing strong spines on the shaft (cross-section). C, D. Inner surface of the theca with proximal rotules of gemmuloscleres. E. Diatomite with loose oxeas. F. Drawings of loose megascleres from the sample with gemmules. A–E, SEM images. Modified from Pisera and Sáez (2003).