Glomerula serpentina (GOLDFUSS, 1831)

Kočí, Tomáš & Jäger, Manfred, 2015, Sabellid And Serpulid Worms (Polychaeta, Canalipalpata, Sabellida, Sabellidae, Serpulidae) From The Rocky Coast Facies (Late Cenomanian) At Předboj Near Prague, Acta Musei Nationalis Pragae Series B 71 (1 - 2), pp. 31-50 : 32-33

Glomerula serpentina (GOLDFUSS, 1831)

Pl. 1, Fig. 1

1831 Serpula gordialis SCHLOTHEIM Varietas serpentina – Goldfuss, p. 240, pl. 71, fig. 4.

1840 Serpula implicata nob. – von Hagenow, p. 668, pl. 9, fig. 17.

1846 Serpula serpentina GOLDFUSS – Reuss, p. 106, pl. 42, fig. 22.

1911a Serpula gordialis, var. serpentina – Frič: p. 72, fig. 304.

1911b Serpula gordialis, var. serpentina – Frič, p. 72, fig. 304.

1961 Glomerula solitaria n. sp. – Regenhardt: p. 28, pl. 9, fig. 11.

1961 Protula rasilis n. sp. – Regenhardt, p. 33, pl. 1, fig. 7.

1961 Omasaria omnivaga n. sp. – Regenhardt, p. 45–46, pl. 5, fig. 7.

1984 Glomerula gordialis ( SCHLOTHEIM, 1820) – Ziegler, p. 215–216, pl. 1, fig. 3–5.

2005 Glomerula serpentina (GOLDFUSS, 1831) – Jäger, p. 130, pl. 1, fig. 1.

2011 Glomerula serpentina (GOLDFUSS, 1831) – Jäger, p. 680–681, pl. 1, fig. 1–7.

2012a Glomerula serpentina (GOLDFUSS) – Kočí, p. 8–9, pl. 1, fig. 1.

2012b Glomerula serpentina (GOLDFUSS) – Kočí, p. 120–122, fig. 1A.

2014 Glomerula serpentina MÜNSTER in GOLDFUSS [sic!] – Jäger, p. 60, fig. 1d.

M a t e r i a l: 40 planispiral specimens, 8 specimens forming glomerulate knots, 74 tube fragments.

S u b s t r a t e: One small tube is attached to a valve of the oyster Amphidonte (Amphidonte) reticulatum ( REUSS, 1846) , another specimen to an Ostrea sp. , and a third one to a pectinid valve.

D e s c r i p t i o n. The tube is coiled to form either glomerulate knots or planispirals. The surface of the tube is smooth without any ornamentation. The tube diameter ranges from 1 to 2.7 mm, usually from 1.3 to 2.2 mm, and in most specimens it measures circa 2 mm. The cross-section of the tube as well as the cross-section of the lumen is circular.

R e m a r k s a n d r e l a t i o n s h i p s. The genus Glomerula ranges from at least the Hettangian to the Recent, and it is common and geographically widespread from the Late Toarcian until the Eocene. Possible Triassic or even Late Palaeozoic representatives of Glomerula are mentioned by Ippolitov et al. (2014). Glomerula serpentina is often a common species in rocky coast facies of the Cretaceous period.

As discussed by Jäger (2005) and Sklenář et al. (2013), distinguishing species of Glomerula is problematic, due to the simple morphology of the tubes which display only a limited number of morphological features and the large variability even within one sample, therefore the schemes presented in previous papers are certainly in part artificial. The occassional presence of trilobate lumina can be used as a feature for taxonomic discrimination between a set of Cretaceous Glomerula species from a more ancient set of Jurassic Glomerula species ( Jäger 2005) which totally lack trilobate lumina. However, a trilobate lumen was not observed by us in thespecimens from Předboj. Within the set of Cretaceous Glomerula species, the usually relative large and usually solitary G. serpentina is the most common. Clusters composed of dozens or even more than a hundred Glomerula tubes occurring mainly in the Santonian and Campanian of South Sweden, North Germany, and England (type area) may be separated taxonomically and determined as G. plexus (J. DE C. SOWERBY, 1829) . Only in fine-grained offshore facies it has proven useful to separate specimens with a small tube diameter as Glomerula lombricus ( DEFRANCE, 1827) .