Lituites dewitzi, Aubrechtová & Korn, 2022

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 : 81-82

Lituites dewitzi sp. nov.

urn:lsid:zoobank.org:act:8A82E920-AAD0-4EC3-A56B-B8D99B40D453

Figs 58B , 60 , Tables 9–10

Diagnosis

Species of the genus Lituites with coiled part diameter of 27 mm; tightly coiled inner volutions, last half whorl detached from the preceding; whorl expansion rate based on conch shape 2.40 and based on whorl height 2.20. Uncoiled part faintly curved, expansion angle 5°. Shell surface of the coiled conch with sharp, prorsiradiate growth lines and lirae, backcoiled part with wide, lamellar lirae and growth lines. Annuli very flat and widely spaced in the backcoiled part.

Etymology

After H.H. Dewitz, who published several important studies on Ordovician cephalopods during the 19 th century.

Type material

Holotype GERMANY • Mecklenburg-Vorpommern, Boltenhagen (Gross Klütz Höved); Ordovician (Lasnamägi Regional Stage, late Darriwilian), Upper Grey Orthoceratite Limestone; MB.C.30538 (illustrated in Fig. 58B ).

Description

Holotype MB.C.30538 ( Fig. 58B ) consists of the coiled part (dm = 27 mm; 1.5 volutions preserved, coiling of inner volutions almost tight or tight, only the last 0.5 volution detached) and the faintly curved backcoiled part (length = 68 mm; wh = 14 mm; EA ~ 5°). The ornament reveals two successive stages: (1) The coiled part (except for the last 60 °) shows sharp growth lines, strengthened to lirae, and annuli, which run almost straight but with a forward direction across the flank. In the ventrolateral area they bend into a shallow ventral sinus. (2) At the end of the coiled part, the narrow lirae transform into wide, lamellar lirae with distances of 0.5 to 1.2 mm. This ornament is retained in the entire preserved backcoiled part. There are delicate growth lines between the raised lirae. Annuli are present in the coiled part and then flatten out towards the backcoiled part, where they are visible only as very flat undulations of the shell wall. In the coiled part, the lateral sinus of ornament elements is not distinctly developed; after uncoiling, it remains shallow and oblique, sloping towards the dorsum. The ventral sinus is deep and rounded with a ventral band (up to wh of 10 mm; Fig. 60 ); the dorsal projection is very low.

Remarks

The type of coiling in Lituites dewitzi sp. nov. is similar to that in L. kruegeri sp. nov. described below, but the former has a much coarser shell ornament, particularly with regard to the lirae. Lituites perfectus differs from L. dewitzi sp. nov. in being eccentrically and openly coiled with conch diameters of up to 40 mm; the backcoiled part in L. perfectus is nearly straight in shape with a lower expansion angle (1°–4°). Lituites dewitzi sp. nov. stands out among the species of the genus Lituites in the prorsiradiate direction of ornament elements in the coiled part of the conch.

Figures

Fig. 58. Species of Lituites from glacial erratics. A. Lituites clavis sp. nov., holotype MB.C.30537 (Neben Coll.) from the Upper Grey Orthoceratite Limestone of Niederfinow (Brandenburg, Germany); previously figured by Neben & Krueger (1971: pl. 31 fig. 3). B. Lituites dewitzi sp. nov., holotype MB.C.30538 (Neben Coll.) from the Schroeteri Limestone of Boltenhagen near Gross Klütz Höved (Mecklenburg-Vorpommern, Germany). C. Lituites nebeni sp. nov., holotype MB.C.30541 (Neben Coll.) from Upper Grey Orthoceratite Limestone of Niederfinow (Brandenburg, Germany); previously figured by Neben & Krueger (1971: pl. 31 fig. 2). Scale bar units = 1 mm.

Fig. 60. Lituites dewitzi sp. nov. from the Schroeteri Limestone; lirae on the venter in holotype MB.C.30538 (Neben Coll.) from Boltenhagen near Gross Klütz Höved (Mecklenburg-Vorpommern, Germany), at wh = 11 mm. Scale bar units = 1 mm.