Key to Nebela – Microworld

Key to Nebela species.

1	Shell with two lateral tubular projections	*N. ansata*
–	Shell without two lateral projections	2
2	Shell mainly chitinoid, with few or no xenosomes	3
–	Shell with a dense covering of scales	4
3	Shell pyriform or sackform, often with a somewhat irregular outline	*N. tenella*
–	Shell broad-elliptical or ovoid, sometimes nearly pyriform, with two lateral pores in the neck	14
4	Scales covering each other partly	5
–	Scales don’t cover each other	7
5	Shell with a ridge or keel	6
–	Shell without ridge or keel	*N. americana*
6	Shell > 150 um	*P. galeata*
–	Shell < 150 um	*N. gracilis*
7	Shell with a distinct broad-elliptical basal part and a narrowing more or less cilindrical neck	8
–	Shell circular, elliptical or flask-shaped	9
8	Shell strongly flattened; neck sometimes widened	*N. lageniformis*
–	Shell elongate drop-shaped, circular or broad-elliptical in cross-section view; neck usually with numerous slender spines	*N. barbata*
9	Shell with a more or less broad ridge or keel	10
–	No ridge or keel present	11
10	Broad ridge or keel, with a different structure than the rest of the shell	*N. carinata*
–	Ridge or keel narrow, sometimes hardly visible	*N. marginata*
11	Shell variable in shape, often with an irregular appearance because of grooves and folds	*N. triangulata*
–	Shell regular in outline	12
12	Shell strongly flattened; length > 180 µm	*N. tubulosa*
–	Shell smaller	13
13	Shell flask-shaped; pseudostome with thick border; length usually < 80 µm	*N. militaris*
–	Shell not flask-shaped; usually larger	14
14	Shell wider than long	15
–	Shell longer than wide	16
15	L. 72–111 µ[1]m, B. 90–133 [1]µm, strongly flattened, with short neck, with inear or slightly curved aperture 19–34 [1]m. Mostly in moist Sphagnum mosses in raised bogs and heathlands	*N. flabellulum*
–	Smaller species, L. 60 [1]µm, B. 70 [1]µm, without neck. In wet Sphagnum	*N. acolla*
16	Larger species, test longer than 100 [1]µm	17
–	Smaller species, test shorter than 100 µ[1]m	18
17	Species with lateral ridge, wide ovoid, with wide linear aperture	*N. aliciae*
–	Species without lateral ridge, pyriform, with very short or almost absent neck, with aperture slightly or strongly curved, or sometimes linear	*N. collaris*
18	Species with protruding neck and narrow aperture, up twisted	19
–	Species with short neck, with linear wide aperture	20
19	Shell drop- or tear-shaped, curved aperture	*N. guttata*
–	Aperture not curved	*N. pechorensis*
20	Shell ovoid or elongated elliptic, aperture linear	*N. tincta*
–	Shell rounded, aperture linear	*N. rotunda*