pforams@mikrotax - Laeviella

Citation: Laeviella Huber et al 2022

Type species: Anomalina bentonensis Morrow 1934

Taxonomic discussion:

The primary criterion for inclusion of La. primuloides, La. bentonensis, La. tururensis, and La. bollii in Laeviella is the presence of a smooth shell surface texture on all but the earliest final whorl chambers and a finely perforate wall ultrastructure.

The oldest species of Laeviella, La. primuloides, is considered a direct descendent of Ticinella primula Luterbacher (text-fig. 2). Evidence for this transition is based on study of the Col de Palluel section (Vocontian Basin, SE France, Gale et al. 2011), which revealed that La. bentonensis (e.g., Pl. 2, Figs. 12, 13) occurs within the range of Ticinella primula (e.g., Pl. 5, Fig. 8), and its first occurrence is just above a morphotype that is intermediate between Ti. primula and La. bentonensis and is denoted as La. primuloides (Pl. 5, Fig. 9). Similar to Ti. primula, La. primuloides has a deeply pitted, irregularly rugose (ticinellid) wall surface texture on the first chambers of the final whorl, but its planispiral coiling mode and smooth wall texture on the last chambers of the final whorl (e.g., Pl. 2, Figs. 1c, 2b, 3c, 4c, 5b, 6b, 7b), justify its inclusion in Laeviella.

Distinguishing features:
Parent taxon (Globigerinelloididae): Test planispiral, chambers globular to radially elongate; aperture at the base of the chamber face and equatorial in position, lateral portions of primary aperture may remain open as new chambers are added, forming relict openings around the umbilical region.
This taxon: Planispiral, wall texture smooth except sometimes pustulose early chambers, weakly lobate with 6-9 chambers in final whorl.

Planispiral, biumbilicate with a shallow, narrow umbilicus, peripheral outline weakly lobate; early chambers rounded and globular, later chambers becoming elongated in growth direction; coiling moderately evolute with 6–9 gradually expanding chambers in the final whorl; sutures radial to slightly curved, weakly depressed; aperture usually a single, symmetrically position, low equatorial arch bordered by a narrow lip, biapertural forms very rare with apertures opening near umbilicus on final chamber.

Finely perforate to macroperforate with average pore diameters of included species ranging from 1.9 microns to 2.6 microns surface smooth on chamber sides, weak pustules sometimes present on early final whorl chambers.

Dimensions of holotype of genotype: 400 microns maximum diameter, 200 microns breadth.

Most likely ancestor: Ticinella - at confidence level 0 (out of 5). Data source: Huber et al 2022 fig. 2.

Geological Range:
Last occurrence (top): near top of Campanian Stage (92% up, 73Ma, in Campanian stage). Data source: Total of range of species in this database
First occurrence (base): near base of Albian Stage (9% up, 111.8Ma, in Albian stage). Data source: Total of range of species in this database

References:

Huber, B. T., Petrizzo, M. M. & Falzoni, F. (2022b). Taxonomy and phylogeny of Albian–Maastrichtian planispiral planktonic foraminifera traditionally assigned to Globigerinelloides. Micropaleontology. 68(2): 117-183. gs

Daughter taxa (time control age-window is: 0-800Ma)
			Laeviella tururensis
			Laeviella bentonensis
			Laeviella bollii
			Laeviella primuloides

test outline:	Subcircular	chamber arrangement:	Planispiral	edge view:	-	aperture:	Interiomarginal
sp chamber shape:	-	coiling axis:	-	periphery:	-	aperture border:	Thin lip
umb chbr shape:	-	umbilicus:	-	periph margin shape:	-	accessory apertures:	None
spiral sutures:	-	umb depth:	-	wall texture:	Smooth	shell porosity:	-
umbilical or test sutures:	Weakly depressed	final-whorl chambers:	6.0-9.0	N.B. These characters are used for advanced search. N/A - not applicable

Laeviella

References:

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