Placostegus zbyslavus ( ZIEGLER , 1984)

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 : 37

Placostegus zbyslavus ( ZIEGLER, 1984)

Pl. 1, Fig. 8

1984 Eoplacostegus dentatus (NIELSEN), 1931 – Ziegler, p. 235, pl. 5, fig.6–7. (NM-O5387 and O5388)

1984 Eoplacostegus zbyslavus nov. spec. – Ziegler, p. 236, pl. 6, fig. 1–2. (NM-O5390)

2009a Placostegus zbyslavus ( ZIEGLER, 1984) – Kočí, p. 98, fig. 2.

2012a Placostegus zbyslavus (ZIEGLER) – Kočí, p. 10, pl. 1, fig. 3.

2012b Placostegus zbyslavus (ZIEGLER) – Kočí, p. 122 –123, fig. 1H.

M a t e r i a l: Two complete specimens with the anterior tube portion preserved and two other specimens with the anterior portion damaged.

S u b s t r a t e: Not preserved.

D e s c r i p t i o n. Tube triangular in cross-section. Attached posterior tube portion planispiral, diameter of spiral at base 3.4–3.7 mm. Free anterior tubeportion rises steeply above substrate, total height 4–5 mm, tube diameter of anterior portion 1.2–1.7 mm. Attached portion has one keel, free portion has three strong but rounded keels. Transverse ornamentation of attached tube portion consists of fine but distinct wrinkles, free tube portion lacks transverse ornamentation. Lumen circular.

R e m a r k s a n d r e l a t i o n s h i p s. Ziegler (1984) described and in part figured several specimens of the present species from different localities. The specimens described as Eoplacostegus dentatus ( BRÜNNICH NIELSEN, 1931) by Ziegler (1984) from Předboj (NM-O5388) and from Kaňk (NM-O5387) belong to Placostegus zbyslavus . They correspond with P. zbyslavus in the triangular cross-section of the planispiral attached tube portion, and they differ from the specimen from the Danian of Denmark described as “ Eoplacostegus (Caesicius) dentatus ( NIELSEN, 1931) ” by Regenhardt (1961) which has denticulated longitudinal keels. Specimen number NM-O5388 has many borings produced by unknown marine organisms. Its attached portion is triangular in cross-section, and the free portion is circular. The specimen of P. zbyslavus NM-O5390 from Zbyslav no. 51 bears transverse ornamentation and has a triangular cross-section.

In addition to these specimens figured by Ziegler (1984), there are some other specimens belonging to P. zbyslavus which were not figured in Ziegler (1984) but, nevertheless, are kept in the collection of his original specimens in the NM Prague. A tube of the present species from Velim-Skalka bears inventory number NM-O5172, the same number had erroneously been mentioned by Ziegler (1984, p. 236) as the number of the holotype of this species, although the figure number 1 is correct (in spite of the wrong plate number, 5 instead of 6) and the correct type locality Zbyslav no. 51 indicate specimen no. NM-O5390 figured on pl. 6, fig. 1 to be the correct holotype. Another unfigured specimen of the present species from Velim has inventory number NM-O5389 which is presumably the correct number, even though Ziegler (1984, p. 253) had erroneously mentioned this number in the figure caption of his so-called “ Eoplacostegus sulcatus ( SOWERBY, 1829) ” from Velim which represents, however, a fine specimen of Laqueoserpula reussi with a rounded quadrangular cross-section and whose correct number, according to the label, is NM-O5167.

Placostegus rigidus ( REGENHARDT, 1961) is rather similar in its triangular tube, but has somewhat sharper longitudinal keels. Cycloplacostegus pusillus (J. DE C. SOWERBY, 1844) has a circular cross-section, and its surface bears fine granulation.