Dorsoserpula wegneri ( JÄGER , 1983)

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 : 138

Dorsoserpula wegneri ( JÄGER, 1983)

Pl. 1, figs 3a-b, Pl. 2, fig. 3

1883 Serpula ampulacea [sic!] SOWERBY; Frič: p. 128, fig. 114 a–b.

1905 Serpula carinata nov. sp; Wegner: p. 152, pl. 8, fig 3 a–c.

1983 Parsimonia wegneri nom. nov; Jäger: p. 38, pl. 4, figs 1–9.

pars 1984 Sarcinella minor nov. spec; Ziegler: p. 220 pl. 2, fig. 4, non fig. 5.

1984 Martina parva nov. spec; Ziegler: p. 227, pl. 3, fig. 9.

1984 Spirorbis asper (VON HAGENOW), 1840 ; Ziegler: p. 242, pl. 7, fig. 6.

1984 Spirorbis subrugosus (MÜNSTER), 1831 ; Ziegler: p. 244, pl. 8, fig. 2.

1984 Spirorbis superminor nov. spec; Ziegler: p. 245, pl. 8, fig. 3.

2005 Dorsoserpula wegneri wegneri ( JÄGER, 1983) ; Jäger: p. 163, pl. 4, figs 3–6.

M a t e r i a l. The original specimen figured by Frič (1883, p. 129, fig. 114) from the Middle Turonian Iserschichten of Choroušky , coll. National Museum, Prague, registration number NM O6057 .

D e s c r i p t i o n. The tube is coiled to form an irregular 3D spiral consisting of 3, 5 whorls lying upon each other. Tube diameter is 4.5 mm. The surface of the tube has a delicate but distinct transverse striation with the striae densely packed and parallel to each other. The tube has a thin wall and is circular in cross-section. During examination of this specimen, one of us (T. K.) detected the very small cross-section of a side tube (‘Nebenröhre‘; Jäger, 1983) at the base of the tube (on the lower left side of the figures).

R e m a r k s a n d r e l a t i o n s h i p s. During joint fieldwork in 2006 at the serpulid-rich Middle Turonian locality Klokočské Loučky we noted in addition to the striking predominance of the species Filograna socialis which is usual for the ‘Iserschichten‘, the absence of Neovermilia ampullacea , and only a single find of the rare Filogranula cincta (GOLDFUSS) by M. J., and the frequent occurrence of a species which resembles Dorsoserpula wegneri . However, all the wegneri -like specimens we found at Klokočské Loučky lack the optional special features of the genus Dorsoserpula , that is the presence of the ‘Nebenröhre‘ and the tube coiling spirally around an upright cylindrical substrate. Similar tubes displaying some variability were found at the same locality during fieldwork between 2001 and 2010 by T. K., one of them has a tube shape similar to D. wegneri and another one (donated to Dr. R. Vodrážka in 2007) has a fine but sharp keel. Determination of our finds had remained uncertain for several years. We even discussed possible affiliation to Parsimonia REGENHARDT , a genus which is indeed similar to Dorsoserpula , but always lacks a “Nebenröhre” and should be considered separate ( Jäger 2005, p. 162) from Dorsoserpula and be restricted to thin-walled, more or less large-sized species in general similar to the type species Parsimonia parsimonia REGENHARDT. For example, the specimens we collected at Klokočské Loučky as well as Frič’s specimen, resemble Parsimonia sp. as described and figured by Jäger (1983; Taf. 4, fig. 10) from the Lower Campanian of Merfeld in northern Germany. However, the recent discovery of a “Nebenröhre” in Frič’s original specimen by one of us (T. K.) clarified the situation: Frič’s original specimen and very probably also our specimens from Klokočské Loučky, which are found in rocks of similar geological age and in similar facies, belong to Dorsoserpula wegneri .

P a l a e o e c o l o g y. Frič’s original specimen as well as many other specimens are attached to a more or less large solid object, for example an oyster valve, which generally is the most common situation in the family Serpulidae . Some other specimens of the genus Dorsoserpula , although only a few specimens in BCB during the Middle Turonian, had become specialized and coiled their tube in the shape of a low 3D spiral around an upright cylindrical object, thereby managing to live a short distance above the sea-floor. Moreover, some specimens of Dorsoserpula form a similar 3D spiral or a less regular ‘ball‘, but without coiling around an upright substrate, being attached only in the juvenile state to some tiny solid object lying on the sea-floor.

O c c u r r e n c e i n B C B. Middle Turonian – Choroušky, Klokočské Loučky.