Systematics of a rare radiolarian—Coelodiceras spinosum Haecker (Sarcodina: Actinopoda: Phaeodaria: Coelodendridae)

We describe a specimen of Coelodiceras spinosum Haecker 1908 [Haecker, V., 1908. Tiefsee-Radiolarien. Wissenschaftliche ergebnisse der Deutschen Tiefsee-Expedition. 14, 1–706] (Sarcodina: Actinopoda: Radiolaria: Phaeodaria: Coelodendridae) collected in a sediment trap deployed in the Indian Ocean, 300 NM WNW off Perth, Western Australia, updating Haeckerʹs 1908 description. Our specimen was collected in the centre of a cold-core eddy at a depth of 300 m. The intact silica structure of the specimen lacked soft organic material, suggesting that the organism was dead when it entered the trap; the traps were deployed for 10 days and did not contain poison or preservative. In this paper, we expand the original description of C. spinosum by Haecker (1908) [Haecker, V., 1908. Tiefsee-Radiolarien. Wissenschaftliche ergebnisse der Deutschen Tiefsee-Expedition. 14, 1–706], using Scanning Electron Microscopy (SEM). Our specimen had three frenula and a short rhinocanna, differing from the single frenulum and long rhinocannae described by Haecker (1908) [Haecker, V., 1908. Tiefsee-Radiolarien. Wissenschaftliche ergebnisse der Deutschen Tiefsee-Expedition. 14, 1–706].