Glomerula BRÜNNICH NIELSEN, 1931

Kočí, Tomáš, 2012, Sabellidae And Serpulidae (Polychaeta, Canalipalpata) From The Locality Kaňk - Na Vrších In Kutná Hora (Upper Cenomanian - Lower Turonian, Bohemian Cretaceous Basin - The Czech Republic), Acta Musei Nationalis Pragae Series B 68 (1 - 2), pp. 7-14 : 8-9

Glomerula BRÜNNICH NIELSEN, 1931 Glomerula serpentina (GOLDFUSS)

Pl. 1, fig. 1

1831

1840 1846 1904 1911 1961 1961 1961 1964 1973

1973

1984

2005 Serpula gordialis SCHLOTHEIM var. Serpentina . – Goldfuss: p. 240, pl. 71, fig. 4.

Serpula implicata – VON HAGENOW: p. 668, pl. 9, fig. 17.

Serpula serpentina GOLDFUSS. – Reuss: pl. 42, fig. 22.

Serpula eximplicata – Rovereto: p. 12, pl. 3, fig. 8a-e.

Serpula gordialis, var. serpentina . – Frič: fig. 304.

Glomerula solitaria n. sp. – Regenhardt: p. 28, pl. 9, fig. 11. Protula rasilis n. sp. – Regenhardt: p. 33, pl. 1, fig. 7.

Omasaria omnivaga n. sp. – Regenhardt: pp. 45-46, pl. 5, fig. 7. Glomerula jerseyensis – Clough: p. 999, fig. 1.

Glomerula solitaria REGENHARDT, 1961 . – Pasternak: p. 10, pl. 1, figs 6-7.

Protula rasilis REGENHARDT, 1961 . – Pasternak: p. 12, pl. 1, fig. 9.

Glomerula gordialis (SCHLOTHEIM, 1820) – Ziegler: pp. 215-216., pl. 1, figs 3, 4, 5.

Glomerula serpentina (GOLDFUSS, 1831) . – Jäger: p. 130, pl. 1, fig. 1.

M a t e r i a l: One specimen attached to an oyster. 15 tube fragments.

D e s c r i p t i o n: Tube circular. Surface smooth. The tube is coiled to form a ball or knots. Lumen circular, a trilobite lumen was not observed in these specimens. Tube diameter ranges from 1.6 to 2.6 mm, in most specimens the diameter is 2 mm.

D i s c u s s i o n: Glomerula serpentina belongs among the typical species of nearshore facies of the BCB. Glomerula serpentina (GOLDFUSS) was considered to belong to G. gordialis SCHLOTHEIM by some authors (for example, Regenhardt 1961, Jäger 1983, Ziegler, 1984) Later Jäger (2005) restricted Glomerula gordialis SCHLOTHEIM to Jurassic material and determined Cretaceous specimens as a separate species, G. serpentina . A similar species, Glomerula lombricus (DEFRANCE) , is distinguished by its small tube diameter which is normally less than circa 1 mm. The systematic position of the genus Glomerula is very problematic. The genus Glomerula has survived from the Hettangian to the Recent, and it is most common and geographically widespread from the Upper Toarcian until the Eocene. Jäger (personal communication) predicts that the genus Glomerula existed as a large number of species, but that it is nearly impossible to separate them because the construction of the tube is so simple and the morphologic variation between specimens even in one sample is extremely wide.

Jäger (1983, 1993, 2005 and personal communication) mentioned that the genus Glomerula did not possess a trilobate lumen even in the Jurassic. From the uppermost Valanginian onwards, trilobate lumina are present, but they are still rare in most samples from the Lower Cretaceous and even in some samples from the Upper Cretaceous. The ability of the animal to produce a tube which in some sections has a trilobate lumen seems to be true phylogenetic progress. Jäger (2005 and personal communication) gave different names to species from the Jurrassic and those from the Cretaceous to Eocene. Trilobate lumina may be present in Glomerula plexus (SOWERBY) , in Glomerula serpentina (GOLDFUSS) , and in Glomerula lombricus (DEFRANCE) , but trilobate lumina are more frequent in G. serpentina than in G. lombricus . Glomerula plexus (SOWERBY) is gregarious, consisting of smooth uniform tubes, each measuring 1-2 mm in diameter, many of these together forming large irregular masses of a bulbous or elongated shape, reaching dimensions of up to 5 cm in the BCB and even larger in some localities, predominantly in the Santonian and Campanian of northern Germany, England, and southern Sweden. Apart from these typical large clusters consisting of dozens or even hundreds of tubes, in many localities it is possible to find two, three or four tubes fixed upon each other. Formally, these small clusters should be named „plexus “, but in reality they probably represent only dense populations of the „normal “ serpentina and lombricus (Jäger, personal communication).