Kiaeroceras kaebliki, Kröger, 2025

Kiaeroceras kaebliki sp. nov.

urn:lsid:zoobank.org:act:50E19EA5-FCD5-4F44-8B9A-2A14C1789E05

Figs 37F, H View Fig , 40C, G

Diagnosis

Kiaeroceras with a CHI of 1.2, with an adult body chamber height of less than 40 mm; mature body chamber slightly longer than high (RBL ca 1.1).

Etymology

From the small bird Käblik (Estonian), referring to the small size of this species.

Type material

Holotype

ESTONIA • Vormsi Island, Saxby shore ; Kõrgessaare Formation , Vormsi Regional Stage; GIT 878-31 View Materials .

Paratypes

ESTONIA • 2 specs; same data as for holotype; GIT 426-1123 View Materials , GIT 878-158 View Materials • 1 spec.; Sutlema quarry ; Kõrgessaare Formation , Vormsi Regional Stage; GIT 878-163 View Materials

Description

Specimen GIT 878-31 is an orthoconic fragment of a mature body chamber and parts of the phragmocone. At the base of the body chamber, the conch height is 37 mm and the width 32 mm (CHI = 1.2). The outer shell is not preserved but the conch surface was apparently smooth. The conch cross section is oval, the conch margin on the prosiphuncular side is more narrowly curved. The body chamber is 40 mm long and has a simple, straight peristome with an inconspicuous, wide hyponomic sinus, ca 3 mm deep, at the antisiphuncular side. The conch height is 34 mm at the peristome. In lateral view, the body chamber is slightly convex, its greatest width occurs at the adapical third of the length with a conch height of 38 mm. The phragmocone height increases from 35 mm to 37 mm at a length of 17 mm (angle of expansion = 7°). The sutures form wide, shallow lobes laterally and have a distance of 5 mm where the conch height is 37 mm (RCL = 0.14). The siphuncle ( Fig. 37H View Fig ) is nearly marginal with a septal foramen 4 mm in diameter, where the conch height is 37 mm (RSH = 0.11).

Specimen GIT 878-1123 is a fragment of a mature body chamber and eight chambers of the phragmocone ( Fig. 40C, G View Fig ). In this specimen, the ontogenetic change of the suture shape is well seen. At a conch height of ca 37 mm, the sutures are nearly straight and 5 mm distant (RCL = 0.14) and ca 20 mm further adorally the sutures form shallow lateral lobes, and are only 2–3 mm apart. The preserved part of the phragmocone is nearly tubular and straight. The siphuncular segments are expanded within the chambers and wide. Endosiphuncular bullettes deposits occur which protract in apical direction from the septal necks ( Fig. 37F View Fig ).

Comparison

This species of Kiaeroceras differs from all other species of the genus in having a small adult size of less than 40 mm conch height at the base of the mature body chamber.