Glomerula serpentina (GOLDFUSS, 1831)

Kočí, Tomáš & Jäger, Manfred, 2013, Sabellid And Serpulid Worms From The Bohemian Cretaceous Basin (Upper Cenomanian - Middle Coniacian) Originally In The Collection Of Professor Antonín Frič, Acta Musei Nationalis Pragae Series B 69 (3 - 4), pp. 129-146 : 135-136

Glomerula serpentina (GOLDFUSS, 1831)

Pl. 3, figs 1a–c, figs 2 a–c

1831 Serpula gordialis SCHLOTH. varietas serpentina ; Goldfuss: p. 240, pl. 71, fig. 4.

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

1845 Serpula serpentina GOLDF ; Reuss: p. 106, pl. 42, fig. 22.

1911 Serpula gordialis , [resp.] var. serpentina ; Frič: p. 72, fig. 304.

pars 1983 Glomerula gordialis ( SCHLOTHEIM, 1820) ; Jäger: p. 26, pl. 2, figs 1–10, 13–18, non figs 11–12.

1984 Glomerula gordialis ( SCHLOTHEIM, 1820) ; Ziegler: p. 215, pl. 1, figs 3–5.

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

M a t e r i a l. The three original specimens figured by Frič (1911, p. 72, fig. 304) from the lowermost Turonian Korycaner “Schichten” of Kamajka (originally named Kamajk or Kamýk) near Chotusice, coll. National Museum, Prague, left specimen NM O7127, middle specimen NM O7128, right specimen NM O7129 according to the original illustrated by Frič .

D e s c r i p t i o n. The two specimens figured by Frič on the left and on the right (on our pl. 3, figs 1a, 1c, 2a and 2c) are irregular planar spirals whereas the specimen in the middle (figs 1b and 2b) is a 3D coiled ball. Specimen figs 1a and 2a measures 12.5 mm x 10.5 mm, specimen figs 1b and 2b is about 8.4 mm high, and specimen figs 1c and 2c is 8.7 mm x 9 mm. Tube diameters for the same order of specimens are respectively, 1.8 mm, 1.4 mm and 1.6 mm. All tubes have a smooth surface and lack trilobate lumina.

R e m a r k s a n d r e l a t i o n s h i p s. A natural scheme of differentiation between species of the genus Glomerula is almost impossible because the tubes are palaeogeographically widepread and have existed since circa 200 million years from the lowermost Jurassic (Hettangian) until today with little change in the general construction of the tube. The more or less smooth tubes lack the most common features, for example ornamentation, which normally enable differentiation between serpulid species. The only obvious phylogenetic progress within Glomerula was the optional introduction of trilobate constrictions into the tube’s lumen somewhere around the Jurassic/Cretaceous transition (the hitherto geologically oldest specimens with trilobate narrowings are found in the uppermost Valanginian) enabling differentiation between a Jurassic set and a Cretaceous to Recent set of Glomerula species. Within the Cretaceous to Recent set further differentiation between fossil species is very artificial, based on distinguishing between small ( G. lombricus ) versus large ( G. serpentina and plexus ) tube diameter and more or less solitary ( G. lombricus and G. serpentina ) versus more or less social, cluster forming ( G. plexus ) occurrence. This artificial scheme had been introduced by one of us (M. J.) and had been slightly modified several times by Jäger (1983, 1993, 2005, 2012), with the latest slight modification introduced by T. K. (in Sklenář et al. 2013), see remarks in the chapter on Glomerula plexus .

Glomerula lombricus (DEFRANCE) occuring in offshore facies on fine-grained sediments is a similar but smaller species with a smooth tube surface. Its tube diameter ranges from 0.4 to 1 mm and is usually 0.5–0.9 mm. The tube diameter of Glomerula serpentina most often ranges from ca. 1 to ca. 2 mm and usually does not exceed 2 mm. Occasionally larger tubes occur, for example in nearshore shallow water deposits in BCB, for example at the locality Velim, where tube diameter may become very large, but when occuring in clusters the number of individual tubes in a cluster is less compared to typical specimens of Glomerula plexus . More detailed remarks and discussion of relationships was published by Kočí (2012) and Sklenář et al. (2013).

P a l a e o e c o l o g y. See Seilacher et al. (2008).

O c c u r r e n c e i n B C B. Upper Cenomanian – Bílina, Brázdim, Hodkovice (Ve skalách), Korycany, Miskovice, Velim, Kamajka, Vítězov. Lower Turonian – Běstvina u Ronova nad Doubravou , Chrtníky, Kamajka, Kaňk, Turkaňk, Nová Ves u Kolína, Předboj, Velim – Skalka, Starkoč, Nová Lhota u Kutné Hory. Middle Turonian – Benátky nad Jizerou , Brandýs nad Orlicí , Česká Třebová, Dolánky u Turnova, Klokočské Loučky, Kokořín, Libuň, Kněžnice, Nouzouv u Svitav, Rovensko pod Troskami, Turnov. Upper Turonian – Čížkovice, Oškobrh, Přerovská hůra, Teplice, Vinařice. Coniacian – Hrdoňovice, Prachovské skály, Valdštejn, Mašov u Turnova .

Glomerula plexus (J. DE C. SOWERBY, 1829)

Pl. 1, fig. 1; Pl. 2, fig. 1

? 1820 Serpulites contorquatus ; von Schlotheim: p. 96.

1829 Serpula Plexus ; J. de C. Sowerby: p. 201, pl. 598, fig. 1.

1831 Serpula vibicata MÜNSTER ; Goldfuss: p. 240, pl. 71, fig. 3 a–b.

pars 1875 Serpula gordialis SCHL ; Geinitz, II: p. 200, pl. 37, fig. 4, non fig. 3.

1889 Serpula gordialis, V. SCHL ; Frič: p. 96, fig. 122.

1961 Filograna congesticia n. sp; Regenhardt: p. 23, pl. 2, fig. 3.

non 1973 Filogarana [sic!] congesticia REGENHARDT, 1961 ; Ziegler: pp. 34–35, pl. 5, fig. 3.

1983 Glomerula plexus (SOWERBY, 1829) ; Jäger: p. 31, pl. 3, figs 1–3.

pars 1984 Filograna congesticia REGENHARDT, 1961 ; Ziegler: p. 214, pl. 1, fig. 1, non fig. 2.

non 1984 Sarcinella plexus (SOWERBY, 1829) ; Ziegler: p. 220, pl. 2, fig. 6.

2005 Glomerula plexus (J. DE C. SOWERBY, 1829) ; Jäger: p. 131.

2013 Glomerula plexus (J. DE C. SOWERBY, 1829) ; Sklenář et al., p. 678, figs 3A–F, 5A, 6Fa.

M a t e r i a l. The original specimen figured by Frič (1889, p. 96, fig. 122) from the Upper Turonian Teplitzer Schichten of Třtěno (Kröndorf) near Chožov, coll. National Museum, Prague, registration number NM O4378 .

D e s c r i p t i o n. The specimen is a ball-shaped mass of irregularly intertwined tubes. It measures 37 mm x 31.2 mm. Tube diameter is very large: 3.3–3.5 mm. All tube have a smooth surface and, as far as visible from outside, lack trilobate lumina.

R e m a r k s a n d r e l a t i o n s h i p s. Differentiation between the more or less solitary G. serpentina and the more or less social, cluster-forming G. plexus is at least in part artificial. The most typical G. plexus clusters from England, Germany and Sweden consist of dozens or even hundreds of tubes, with the whole cluster showing a tendency to form either a bundle or a large ball or dome. However, at many localities where Glomerula tubes are common, small clusters occur composed of two to circa five tubes, thereby standing morphologically between serpentina and plexus . Are these finds small examples of G. plexus , or are they only by-chance aggregates of a few G. serpentina tubes which attached to each other due to dense spatfall in this area of the sea-floor, sparsity of solid substrates on a generally soft sea-floor, and general tendency of the genus Glomerula to adnate its tube closely to solid objects of any kind, including earlier-built portions of its own tube or tubes of other Glomerula individuals? While M. J. generally tends to affiliate the small clusters composed of two to circa five tubes to G. serpentina , we nevertheless agreed with the suggestion of T. K. (in Sklenář et al. 2013) that in the Teplice Formation of the Úpohlavy quarry all finds of large tube diameter should be determined as G. plexus and that G. serpentina does not occur at Úpohlavy. The reason for our decision was that medium-sized clusters composed of two to circa five tubes are relatively common here and that many of the tube fragments found in a solitary state seem to be only fragments of such clusters or fragments of ‘seeking‘ tubes growing off from a cluster so that differentiation between the two species seems senseless here. The medium-sized cluster figured by Frič clearly matches the finds from Úpohlavy and was found in the Teplitzer Schichten and therefore presumably in the same layer, even though there are, of course, differences in the detailed ranges of Teplitzer Schichten and Teplice Formation. However, it must be stated that even in the Teplitzer Schichten or Teplice Formation the Glomerula plexus clusters are on one hand never composed of as many tubes as in typical plexus clusters found in England, Germany or Sweden, but that on the other hand in the Teplitzer Schichten or Teplice Formation the tube diameter may grow much larger compared to the moderate size of tubes in typical plexus clusters. For more detailed remarks and discussion of Glomerula and its species see Sklenář et al. (2013).

P a l a e o e c o l o g y. This species was adapted to life on the soft bottom. The thin-walled sabellids use the same strategy as corals, which use dead portions of their own skeleton as an anchor. Similarly, sabellids use previously built, abandoned portions of their own tube or other tubes within their cluster as an anchor for attachment, after the primary attachment had been to a lithoclast or bioclast of any kind. The spaghettiform, smooth tubes of the sabellid cluster grow fast in length but relatively slowly in diameter so that in a fragment one can often not decide which end had been posterior and which anterior (for example, Seilacher et al. 2008, fig. 3A).

O c c u r r e n c e i n B C B. Upper Turonian – Křtěnov, Čížkovice, Úpohlavy, Radovesice.