Holmiceras Hyatt, 1894

Aubrechtová, Martina & Korn, Dieter, 2022, Taxonomy and ontogeny of the Lituitida (Cephalopoda) from Orthoceratite Limestone erratics (Middle Ordovician), European Journal of Taxonomy 799 (1), pp. 1-108 : 44-45

publication ID	https://doi.org/10.5852/ejt.2022.799.1681
publication LSID	lsid:zoobank.org:pub:F52DBAB0-38C7-400F-9BA1-E2D8E6B19E7E
DOI	https://doi.org/10.5281/zenodo.6343262
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treatment provided by	Felipe (2022-03-09 13:14:35, last updated 2024-11-26 02:31:49)
scientific name	Holmiceras Hyatt, 1894
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Genus Holmiceras Hyatt, 1894

Type species

Lituites praecurrens Holm, 1891 ; subsequent designation by Sweet (1958).

Diagnosis

Genus of the family Lituitidae with 1 to 1.5 loosely coiled volutions of the coiled conch; uncoiled part short, sigmoidal, with expansion angles of 7°–20°. Whorl profile either slightly compressed or somewhat depressed. Chamber length between 0.20 and 0.30 of the whorl height. Shell surface with annuli and/or lirae; lateral and dorsal sinuses and ventrolateral and dorsolateral projections in the apical parts of the conch, but adorally, the ventral and dorsal sinuses disappear so, that on the mature body chamber, the venter and dorsum are occupied by broad projections (after Sweet 1958).

Species included

Holmiceras benneti Flower, 1975 ; Orthoceras coreanicum Kobayashi, 1928 ; Lituites Kjerulfi Brøgger, 1882 ; Lituites praecurrens Holm, 1891 ; Holmiceras sichuanense Lai, 1986 ; Holmiceras havelense sp. nov.

Remarks

The species of Holmiceras are morphologically closely similar to species of Ancistroceras , which have a smaller and tightly coiled juvenile conch and attain greater expansion angles (usually between 20 and 30°). The conch shapes in the species of Holmiceras are also somewhat similar to those in Angelinoceras because the uncoiled conch in both genera expands rapidly. The species of Angelinoceras have much larger general dimensions, though, with coiled conch diameters of 30–50 mm. The species of the genus Lituites generally have lower expansion angles ( Fig. 30 View Fig ), larger overall conch sizes and mature aperture with five projections and deep sinuses on the ventral and lateral sides of the conch. Sweet (1958), Dzik (1984) and Fang et al. (2021) discussed the phylogenetic relationships of Holmiceras in greater detail.

Geographic and stratigraphic occurrence

Canada, Norway, Sweden, northern Germany, Korea and China; Middle to Late Ordovician.

The type species H. praecurrens is a stratigraphically significant species in the Orthoceratite Limestone of Baltoscandia, indicating a Kundan age ( Evans et al. 2014).

References

Dzik J. 1984. Phylogeny of the Nautiloidea. Palaeontologia Polonica 45: 1 - 219.

Evans D. H., King A. H., Histon K. & Cichowolski M. 2014. Nautiloid cephalopods - a review of their use and potential in biostratigraphy. Denisia 32: 7 - 22.

Fang X., Pohle A., Kroger B., Aubrechtova M., Burrett C., Zhang Y. & Zhang Y. 2021. Phylogeny of Middle - Late Ordovician lituitid cephalopods based on cladistic analysis. Journal of Systematic Palaeontology 19 (9): 633 - 650. https: // doi. org / 10.1080 / 14772019.2021.1944354

Flower R. H. 1975. American Lituitidae (Cephalopoda). Bulletins of American Paleontology 67: 139 - 173.

Holm G. 1891. Om mynningen hos Lituites Breyn. Geologiska Foreningen i Stockholm Forhandlingar 13: 736 - 780. https: // doi. org / 10.1080 / 11035899109445850

Hyatt A. 1894. Phylogeny of an acquired characteristic. Proceedings of the American Philosophical Society 32: 349 - 647. https: // doi. org / 10.5962 / bhl. title. 59826

Lai C. 1986. On Lituitidae. Bulletin of the Chinese Academy of Geological Sciences 12: 107 - 126.

Sweet W. C. 1958. The Middle Ordovician of the Oslo region, Norway. 10. Nautiloid cephalopods. Norsk Geologisk Tidsskrift 38: 1 - 176.