The identification of Nebela and similar species
with indications on their ecology and distribution
Edward A. D. Mitchell, University of Neuchâtel
Disclaimer. This is a grossly simplified key of some main types. The true diversity of the genus is much higher both considering described taxa, and certainly even more so if pseudo-cryptic and cryptic taxa are considered. Still imperfect as this document is hopefully it will be useful. Any suggestions for improvement are very welcome!
The genus Nebela contains some of the most beautiful and common species of testate amoebae, among which many easily identifiable species such as N. militaris, together with some more problematic taxa such as the N. tincta-collaris group and some obscure, easily overlooked species such as N. longicollis and N. acolla. The Nebela s.l. species cover a wide range of morphological variations, possibly derived from a single ancestral type (Fig. 1). The general morphology of most taxa appears to be quite constant, although considerable variation can be found, especially for small details of the test.
Goal of the key, source of the information and copyright issues
This illustrated key aims to allow the identification of Nebela s.l. species, especially for scientists who do not read French or German, languages in which many of the earlier papers on testate amoebae were written. This key is not a review of the genus. Many taxa described since Deflandre’s 1936 monograph are not included here. This key includes 43 taxa treated as Nebela by Deflandre key. This selection probably covers the majority of Nebela s.l. species likely to be found in nature, at least in the northern hemisphere. Two Schoenbornia species are also included, but the Quadrulella species treated as Nebela species by Deflandre and for which he created a subgenus are not included.
This document was translated and adapted from the following sources: (Cash et al., 1905-1921; Deflandre, 1936; Lüftenegger et al., 1988; Meisterfeld, 2000; Penard, 1902; Schönborn et al., 1987). Parts of this key were adapted from the general key to the Nebelidae of Meisterfeld. No formal copyright authorization was asked for using Meisterfeld’s criteria nor for using the illustrations and therefore, until further notice, this document is limited to personal use.
General notes on the choice of taxa
Most of the taxa included in this key are those that were in the 1936 monograph of Deflandre. In his chapter of the illustrated guide to the protozoa, Meisterfeld included several other genera in the key to the Nebelidae, some of which, such as Schoenbornia, may use mineral xenosomes in addition to siliceous plates derived from other protists to build their shells. In most cases I followed Meisterfeld’s selection and in all cases his taxonomic treatment. However, some species included in Meisterfeld’s key were excluded from this key. Geamphorella Bonnet, 1959, a species from humic calcareous soils, and Pseudonebela Gauthier-Lièvre, 1953, an aquatic species found in tropical swamps. Although these two species share some morphological traits of the Nebelidae family, they are currently not included in the Nebelidae family and are treated as Incertae Sedis.
Fig. 1 General view of the morphological diversity of Nebela s.l. taxa and hypothetical phylogenetic relationships between them derived from either N. collaris (A-G, H-L. M-O) or from Argynnia dentistoma (P-U, P-R, V-X) (from Deflandre, 1936). A, N. collaris (broad and lateral views); B, N. tubulosa, C, N. marginata; D, N. carinata; E, N. equicalceus; F, N. saccifera; G, N. ansata; H, N. longicollis; I, N. wailesi; J, N. lageniformis; K, Alocodera cockayni; L, Apodera vas; M, N. tincta; N, N. tincta var. rotunda; O, N. flabellulum; P, Argynnia dentistoma; Q, Argynnia dentistoma var. lacustris; R, N. barbata; S, Argynnia caudata; T, Argynnia spicata; U, Argynnia columbiana; V, Argynnia triangulata; W, Argynnia triangulata; X, Argynnia bipes.
– Key –
For the “standard” Nebela species such as N. tincta and N. collaris, go directly to 31.
Abbreviations: L: Length; W: Width; H: Height (or depth); P: Pseudostome (aperture) width.
|1||Margins of the pseudostome (aperture) bordered by siliceous plates, or quartz grains, no smooth organic rim (in case of doubt, check also other option)||2|
|–||Pseudostome with organic rim or lip||11|
|2||Pseudostome folded back at the collar, sometimes only visible as a slight thickening ofthe pseudostome, which then opens up like a vase Physochila Jung, three species treated here:||3|
|–||Pseudostome oval, bordered with siliceous plates, margin irregular||5|
|3||Test circular in cross section||4|
|Test compressed in cross section, Back folding of the aperture usually not very clear. L. 68-84 µm, W. 40-60 µm, H. 30-39 µm. Sphagnum mosses in Peatlands. Europe (Jura, NL, Germany, UK) and North America, but uncertain. Fig 2, f-h||Physochila tenella|
Fig. 2 a-e, Physochila griseola (b, e apical views); f-h, P. tenella (h, lateral view); i-j, P. cratera; a-h from Penard, i-j from Wailes, in Deflandre.
|4||Sides converging towards the aperture. L. 70-85 µm, W. 50-58 µm. Sphagnum and other wet mosses. Europe (Ireland, Germany, France), North America, Australia, probably cosmopolitan. Fig. 2, a-e||P. griseola|
|–||Test composed of an almost spherical main part and a 30 to 35 µm long neck with parallel sides. L. 120-135 µm, W. 74-80 µm. Submerged Sphagnum. North America (New-Jersey). Fig. 2, i-j||P. cratera|
|5||Test regular, oval to pear shaped, possibly with slender spines, but without hollow horns||6|
|–||Test either with 2 to 8 hollow horns, or very irregular in shape (trapezoid), Argynnia Vucetich, five horned species treated here||8|
Fig. 3 a & b, Nebela barbata (b in side view) (from Wailes and Penard in Deflandre)
|6||Test drop-shaped with numerous slender spines protruding from all parts of the shell except the tip of the neck and aperture. L. 80-160 µm, W. 40-60 µm. The distinctive morphological characteristics of this species calls for its removal from the Nebela genus. Wet Sphagnum in peatlands. North America, UK, France (Brittany and Landes), possibly a species restricted to the Atlantic coasts of Europe and North America. Fig. 3||N. barbata|
|–||Test lacking spines, three hornless species treated here Argynnia Vucetich||7|
|7||Shell generally larger, 170-200 µm, but extremes for the type range between 155 and 258 µm and varieties may be as small as 95 µm! Shell usually yellowish, scales flat, angular (although somewhat rounded at the edges), outline often (in at least 30% of the cases) irregular, with small dips and humps. Aquatic species, in big lakes. Switzerland (Lake Leman), Scotland (Loch Ness), North America. Fig. 4||Argynnia vitraea|
Fig. 4. a-f, Argynnia vitraea (b & f, lateral views, d, detail of the test surface) (from Penard in Deflandre).
|Varieties of Argynnia vitraea:|
|–||Smaller than type: L. 115-155 µm, W. 70-100 µm. Shell covered mostly by circular plates mixed with polygonal plates. Wet Sphagnum and Hypnum in peatlands: North America, France (Haute-Savoie). (Not illustrated).||var. minor|
|–||Much smaller than type: L. 95-120 µm Wet Sphagnum mosses in raised bogs: UK, North America, France. (Not illustrated)||var. sphagni|
|–||Shell size generally smaller, mostly 80-90 µm, but the type and varieties range between 66 and 206 µm! Shell not yellowish, scales round or oval, outline regular. Wet and moist Sphagnum and other mosses, in peatland and siliceous (acidic?) ponds with an accumulation of organic matter. Cosmopolitan. Fig. 5, a-c||A. dentistoma|
|Note 1. In his 1902 monograph, Penard renamed N. dentistoma to N. crenulata because the name N. dentistoma was a chimera of Latin and Greek.|
|Varieties of Argynnia dentistoma:|
|–||Smaller than type and pseudostome straight. Poorly delimited variety according to Deflandre. Ecology and distribution not given. (Not illustrated).||var. laevis|
|–||Larger than type: L. 155-190 µm, W. 100-142 µm, P. 32-50 µm, H. 50-80 µm. Sphagnum mosses. South-America (Chile, Brazil). Fig. 5 e.||var. hesperia|
|–||Larger than type, outline longer with a proportionally narrower pseudostome than type. Pseudostome crenate, not straight. Larger than type: L. 120-206 µm, W. 100-143 µm, P. 25-45 µm, H. 64-90 µm. Sphagnum mosses. North America. Fig. 5 f||var. lacustris|
|–||Shell size generally smaller: L. 78-82 µm, W. 57-59 µm, P. 18-19 µm, H. 40 µm. Pseudostome crenate (see also A. dentistoma var. lacustris). Shell colorless. Sphagnum mosses. U.K. Fig. 5 g-i||Argynnia scotica|
Fig. 5 a-c Argynnia dentistoma (from Penard in Deflandre); d, A. dentistoma var. lageniformis (from Playfair in Deflandre; e, A. dentistoma var. hesperia; f, A. dentistoma var. lacustris (from Wailes in Deflandre); g-i, A. scotica (from Brown in Deflandre).
|Note 2. Deflandre considered N. scotica to be a variety of N. dentistoma rather than a proper species.|
|8||Test outline regular (excluding the 3 to 8 hollow horns) oval to pear shaped||9|
|–||Test and irregular trapezoid shape, either with two horns, or without horns||10|
Fig. 6 a-c, Argynnia caudata (from Leidy in Deflandre); d, A. caudata (from Playfair in Deflandre); e-g, A. spicata (from Wailes in Deflandre); h, A. caudata; i, A. spicata; j & k, A. columbiana (from Wailes in Deflandre). Images i to k are drawn at the same magnification to illustrate the size differences among the three species.
|9||Smaller species, L. without horn 76-90 µm, W. 58-70 µm, 4 hollow horns (range 3-5), length of the horns: 16-24 µm. Sphagnum mosses. North America (U.S. and Canada), South-America (Brazil, Bolivia, Peru), Sumatra, Australia, Europe (U.K., absent from continental Europe?). Fig. 6 a-c & h||A. caudata|
|–||Medium-sized species, L. without horn 120-140 µm. W. 100-125 µm. Sphagnum mosses. South-America (Colombia, Peru). Fig. 6 e-g & i||A. spicata|
|–||Larger species, L. without horn 174-210 µm, W. 140-168 µm. Sphagnum and other wet mosses in peatlands. North America (British Colombia). Fig. 6 j||A. columbiana|
Fig. 7 a-d, Argynnia bipes (a, in side view) (after Wailes and Penard in Deflandre)
|10||Test with two conical horns at the aboral end. L. 132-155 µm, W. 72-103 µm. Planktonic species in siliceous (acidic?) ponds. U.K. China, North America. Fig. 7||A. bipes|
|–||Test without horns, shape variable, usually approximately trapezoid. L. 80-100 µm, W. 60-80 µm. Sphagnum mosses. U.K., N.L., Japan, South-America (Colombia). Fig. 8||A. triangulata|
Fig. 8 a-e, Argynnia triangulata (after Edmondson in Deflandre).
|11||In broad view two invaginated frontal pores on each side, connected by an internal tube||12|
|–||Pores absent, or if present located on the narrow side of the shell||15|
|12||Two groups of small internal teeth near the aperture. Sphagnum mosses. Southern hemisphere, see detail for the species. Certesella Loebloch & Tappan, thee species treated here||13|
|–||No groups of small internal teeth. L. 135-170 µm, W. 87-110 µm. Sphagnum and other mosses. U.K., Germany. Fig. 9||Porosia bigibbosa|
Fig. 9 a-c, Porosia bigibbosa (c in side view) (a, after Penard, b, after Wailes in Deflandre).
|13||L. <140 µm, test in broad view ellipse-shaped with a short straight neck approximately 1/3 of the total length. The lateral pores are located on either side of the base of the neck. L. 120-136 µm, W. 95-100 µm. Sphagnum mosses. Southern hemisphere: South-America (Chile, Brazil). Fig. 10 a & b||Certesella murrayi|
|–||L. >145 µm, neck either with parallel sides or test pear shaped with convergent sides. Two lateral pores present on the narrow site of the test||14|
|14||L. 145-150 µm, colorless or light yellow. Sphagnum mosses. Southern hemisphere: South-America (Colombia, Cape Horn), Australia, Islands of the Pacific Ocean. Fig. 10 f–l||Certesella certesi|
|–||L. 155-170 µm, W. 85-91 µm. Straw-yellow color, translucent. Sphagnum mosses. Southern hemisphere: South-America (Colombia, Cape Horn), Australia, New Zealand, Macquarie Islands (Pacific Ocean). Fig. 10 c-e||Certesella martiali|
|Note 3. The distinction between C. certesi and C. martiali is not obvious, apart from the size. The descriptions given by Deflandre do not suggest any other clear criterion for separating between these two species.|
Fig. 10 a & b, Certesella murrayi (after Wailes in Deflandre); c–e, C. martiali (c after Certes, d & e after Penard in Deflandre); f-l C. certesi (f & g after after Penard, h-j after Certes, k & l after Heinis, in Deflandre);
|15||Shell with a distinctly separated, sometimes swollen neck||16|
|–||Shell pyriform (pear-shaped), oval, elongate, or with a lateral indentation on each side||18|
|16||Neck not deeply constricted Nebela subgroup Lagenoides||17|
|–||Neck deeply constricted at the junction with the main part of the test. L. 130-210 µm, W. 85-103 µm. Sphagnum mosses. Distribution generally considered to being restricted to the Southern hemisphere: South-America (Cape horn, Colombia, Chile, Brazil), Australia, Fiji Islands, Hawaii (n.b. not in the Southern Hemisphere!). Wailes cites British Colombia, but Deflandre assumes that this is an error and that what Wailes meant was Colombia because Heinis reported this species in that country (Heinis, 1914; Wailes, 1913). Fig. 11||Apodera vas|
Fig. 11 a-c. Apodera vas (b, in side view)
(a & b, after Certes, c, after Penard, in Deflandre)
|17||Largest species, test L. 125-130 µm, W. 70-82 µm, covered with large, elliptic or polygonal and rounded scales, either transparent or slightly yellow. Sphagnum and other moist and wet mosses, in forests, peatlands and ponds with an accumulation of organic matter. Cosmopolitan. Fig. 12 a-c||N. lageniformis|
|Variety of N. lageniformis:|
|–||Test L. 128-135 µm, covered with elliptic scales mixed with aperture plates of Euglypha species (E. strigosa, E. ciliata). In side and front views, proportionally wider than N. lageniformis with a pointed profile. Ecology not given. South-America (Colombia). Fig. 12 d & e||N. lageniformis var. cordiformis|
|Mid-size species, test L. 75-100 µm, W. 52-58 µm, covered with polygonal scales not rounded at the angles, colorless. In addition to the dimensions and shell characteristics, the outline of the test is narrower than N. lageniformis. Sphagnum and other wet mosses. Probably cosmopolitan. U.K., continental Europe, North America, Australia. Fig. 12 f & g||N. wailesii|
|Smaller species, test L. 55-74 µm, W. 28-48 µm, covered with circular and oval plates. Sphagnum mosses. Probably cosmopolitan. U.K., North America, Seychelles, France. Fig. 12 h & i||N. tubulata|
Fig. 12 a-c Nebela lageniformis (b: side view); d & e, N. lageniformis var. cordiformis (e: side view); f & g, N. wailesii (g broad and side views); h & i, N. tubulata; (a, b, f & h, after Penard, c, g, & i after Wailes and Penard, d & e, after Heinis in Deflandre)
|18||Shell with a flat (not hollow) lateral ridge of variable width (length), but no other specific morphological traits such as lateral extensions (“arms”), hollow keels, or indentations Nebela subgroup Carinatoides||19|
|–||Shell without flat lateral ridge or, if present, lateral extensions or indentations also present||22|
|19||Ridge wide, conspicious||20|
|–||Ridge narrow (may be overlooked), test L. 140-170 µm||21|
|20||Medium to large species, L. 140-230 µm, W. 110-130 µm. Very humid or wet Sphagnum mosses in peatlands. North America, U.K., continental Europe, probably cosmopolitan. Fig. 13 a-f||N. carinata|
|–||Large to very large species. L. 275-295 µm. In side view, the bottom of the test is more pointed (see Fig. 13 n). Shell covered by large plates mixed with smaller plates (Fig. 13 o). In Sphagnum mosses in a peatland. Russia (Gov. Archangelsk.). Fig. 13 m-o||N. spumosa|
Fig. 13 a-f, Nebela carinata (b & e, side views); g & h, N. marginata (side view);
i–l, N. maxima (j, side view); m–o, N. spumosa (n, side view); (a, b, g & h, after Penard, c–f, after Cash, i-o, after Awerintzew in Deflandre).
|21||L. 140-170 µm, W. 90-105 µm. The ridge starts about in the middle of the length of the test. Very humid or wet Sphagnum mosses in peatlands. Probably cosmopolitan. Fig. 13 g & h||N. marginata|
|–||Largest species in the genus. L. 280-325 µm. The ridge starts about 1/3 from the aperture. In Sphagnum mosses in a peatland. Russia (Gov. Archangelsk). Fig. 13 i–l||N. maxima|
|22||No lateral indentation||26|
|–||Lateral indentations on each side, either at the base of the neck or presence of well-developed lateral “arms”. Continuous or discontinuous flat lateral ridge present or absent||23|
|23||Flat lateral ridges present||24|
|–||Flat lateral ridges absent||25|
|24||Flat lateral ridges continuous, present between the arms and the main part of the test and extending around the aboral end. L. 252-260 µm, W. 140-160 µm. Wet Sphagnum mosses, North America, U.K. Fig. 14 a||N. equicalceus|
|–||Flat lateral ridges discontinuous, present only between the arms and the main part of the test but absent from the aboral end. L. 203-240 µm, W. 126-145 µm. Sphagnum mosses, North America. Fig. 14 b & c||N. saccifera|
|25||Presence of well-developed lateral arms. Similar to N. saccifera or N. equicalceus, but without the flat ridge. L. 216-260 µm, W. 132-164. Sphagnum mosses. North America. Fig. 14 d||N. ansata|
|–||Lateral indentation at the base of the neck. Two lateral pores sometimes present. Shell transparent, yellowish. L. 89-136 µm. Sphagnum mosses. Southern Hemisphere: South-America (Chile), Auckland Islands, Australia, New-Zealand. Fig. 14 e & f||Alocodera cockayni|
Fig. 14 a Nebela equicalceus; b & c, N. saccifera (c, side view), d, N. ansata; e & f, Alocodera cockayni (f, side view); (a & d, after Leidy, b & c, after Wailes, in Deflandre).
|26||Presence of a thick, hollow keel visible in side view||27|
|–||Hollow keel absent||29|
|27||Large species, L. > 160 µm||28|
|–||Smaller species, L. 90-130 µm, W. 50-60 µm. Sides converging gradually towards the aperture. No distinct neck. Wet Sphagnum mosses. North America, South-America (Peru), U.K., Switzerland, France, Seychelles (Mahe), Probably cosmopolitan. Fig. 15 a-d||N. gracilis|
Fig. 15 a-d Nebela gracilis (b, side view, d view from the apical end); e & f, N. pulcherrima (f, side view); g & h, N. galeata; (a & b, after Wailes; c, d, g & h, after Penard, e & f, after Awerinzew, in Deflandre).
|28||Presence of a distinct neck with parallel sides both in frontal and lateral views. Pseudostome straight. L. 180-185 µm, W. 100 µm. Sphagnum mosses. Russia (Archangelsk). Fig. 15 e & f||N. pulcherrima|
|–||Sides converging more gradually towards the pseudostome. Pseudostome curved. L. 180-200 µm, W. 98-114 µm. Lateral pores sometimes visible. Aquatic species. Sphagnum and other mosses in peatlands. Probably cosmopolitan. Fig. 15 g & h||N. galeata|
|Variety of N. galeata:|
|–||Wider than type. Lateral pores generally visible. Main part of the test circular prolonged by a short neck. Lateral view similar to type. L. 166-208 µm, W. 140-170 µm. Aquatic species. Sphagnum and other mosses in peatlands. France (Haute-Savoie)||N. galeata var. orbicularis|
|29||Test compressed, medium to large species, usually > 50µm, test usually covered with recycled siliceous plates, sometimes test lacking scales, mineral xenosomes never present Nebela subgroup Collaroides||31|
|–||Test circular in cross section, at the most slightly compressed, composed of irregular flat platelets, sometimes mixed with agglutinated rough mineral xenosomes. Small species, usually < 45 µm Schoenbornia||30|
Fig. 16 a-d, Schoenbornia humicola (c, frontal view) (after Schoenborn et al.)
|30||Small to medium-sized species, test round in cross section. L. 26-44 µm, W. 16-26 µm, P. 8-30µm. Soil humus, especially in acid humus (moder and raw humus), rare in mull. Probably cosmopolitan. Fig. 16||Schoenbornia humicola|
|–||Small species, L. 14-18 µm. Test round or slightly compressed in cross section (W. 10-13, H. 7-11). Pseudostome circular or oval 7-11 x 4-6 µm. Soil humus, especially in acid humus (moder and raw humus). Probably cosmopolitan. Fig. 17||Schoenbornia viscicula|
Fig. 17 a-e, Schoenbornia viscicula; a, broad lateral view; b, side view; c, view from oral end, d & e, SEM-microphotographs: d, broad lateral view; e, view from oral end (after Luftenegger et al.)
Note 4. The distinction between the two Schoenbornia species and some other species of the genera such as Pseudodifflugia and Phryganella may not be easy. Until more detailed comparative studies are undertaken and good illustrations and identification criteria are provided, misidentifications are almost inevitable.
|31||Test longer than wide. At the most test outline round||32|
|–||Test wider than long||33|
|32||L. 72-96 µm, W. 90-110 µm. Short neck present. Moist Sphagnum mosses in raised bogs and heathlands. North America, U.K., N.L., Westphalia, France (Normandy and Brittany). Probably limited to the Atlantic coasts of Europe and North America. Fig. 18 a||N. flabellulum|
|–||L. 60 µm, W. 70 µm. No neck. Wet Sphagnum mosses. U.K. Fig. 18 b & c||N. acolla|
Fig. 18 a, Nebela flabellulum; b & c N. acolla (c in apical view)
(after Cash in Deflandre)
|33||L./W. ratio = 2 or more||34|
|–||L./W. ratio < 2||37|
|34||L./W. ratio = about 3, L. 120-140 µm, W. 40-45 µm, pseudostome curved. Shape similar to a long N. militaris, but lateral pores absent. Sphagnum mosses. Rare. Weisbaden (Germany?). Fig. 19||N. longicollis|
Fig. 19 a-e Nebela longicollis (after Penard in Deflandre)
|–||L./W. ratio = about 2, sides converging towards the pseudostome, lateral pores present, often causing a disruption in the outline of the test||35|
|–||In lateral view base of the shell broad rounded||36|
|35||In lateral view base of the test tapering to a narrow, sometimes angular tip, large species: L. 190-215 µm, W. 80-125 µm. Aquatic species, wet Sphagnum and other mosses in peatlands. Cosmopolitan. Fig. 20 a-c||N. tubulosa|
Fig. 20 a-c, Nebela tubulosa (b, detail of the lateral pores, c in side view); d-f, N. militaris (f in side view); (after Penard in Deflandre)
|36||Small species. L. 50-72 µm, W. 25-38 µm. Shape very characteristic. Lateral pores always clearly visible. Pseudostome clearly curved. Sphagnum and other moist mosses in peatlands and forests. Cosmopolitan. Fig. 20 d-f||N. militaris|
|–||Large species. L. 140-175 µm, W. 65-75 µm. Very hygrophilous or aquatic species, wet Sphagnum and other mosses in peatlands and transitional mires. North America, U.K., N.L. France, Central Europe, Switzerland, etc. Probably cosmopolitan. Fig. 21 a-c||N. penardiana|
|Variety of N. penardiana:|
|–||Anterior part of the shell bent, L. 130-170 µm. Ecology not given, North America. (Not illustrated)||N. penardiana var. falcata|
|–||Very large species: L. 236-272 µm, W. 115-123 µm. Wet and submerged mosses in raised bogs. France, North America (Westphalie). Fig. 21 d-f||N. speciosa|
Fig. 21 a-c, Nebela penardiana (b in side view); d-f, N. speciosa (f in side view) (a-c, after Penard in Deflandre, d-f, after Deflandre)
|–||Lateral pores present (sometimes hard to see and causing endless confusion with N. parvula, N. bohemica, N. minor, and N. collaris!), L. 76-92 µm, W. 56-64 µm. N. b. see also N. militaris above. Moist and very moist Sphagnum and other mosses in peatlands and forests. Cosmopolitan. Fig. 22 a-c||N. tincta|
|Varieties of N. tincta:|
|–||Test outline rounded, almost perfectly round, L. 70-90µm, W. 60-85 µm. Same ecology as type and likely also cosmopolitan. (Not illustrated).||N. tincta var. rotunda|
|–||Larger than type, L. 90-120 µm, but always with the characteristic two lateral pores. Ecology and distribution not given, according to my findings similar to type. Fig. 22 d & e||N. tincta var. major|
Fig. 22 a-c Nebela tincta (b & e antapical view); d & e, N. tincta var. major (after Penard in Deflandre)
|38||Pseudostome curved, in lateral view notched||39|
|–||Pseudostome straight, in broad and lateral views||40|
|39||Larger species, L. > 100 µm, tests pear-shaped, pseudostome proportionally narrower (a tentative threshold is suggested here: P/L < 25%). Moist and wet Sphagnum and other mosses in peatlands, forests and siliceous humic ponds. Cosmopolitan. Fig 23 a & b||N. collaris|
|–||Smaller species, L. < 100 µm, pseudostome proportionally wider (suggested threshold: P/L > 25%) giving this species a less “elegant” look. Sphagnum and forest mosses. Cosmopolitan. Fig. 23 c & d||N. minor|
Fig. 23 a & b, Nebela collaris; c & d, N. minor (b & d, side views) (after Penard in Deflandre)
|40||Larger species (but with size overlap!), L. 85-125 µm, W. 61-105 µm, test opaque, similar to N. collaris except for the shape of the pseudostome. Moist and wet Sphagnum and other mosses in peatlands, forests and siliceous humic ponds. Probably cosmopolitan although not recognized by many authors and possibly overlooked for that reason. Fig. 23 c & d||N. bohemica|
|–||Smaller species (but with size overlap!), L. 78-90 µm, W. 55-58 µm, test very transparent. N. b. Similar sized N. tincta always has lateral pores and may be transparent. Sphagnum and moist forest mosses. Cosmopolitan. Fig. 23 a & b.||N. parvula|
Fig. 24 a & b, Nebela bohemica; c & d, N. parvula (b & d, side views) (a & b after Penard, c & d after Cash, in Deflandre)
Copyright Edward Mitchell 2003. All material can be used freely for non-profit educational purposes. An acknowledgement for such a use would be appreciated.
I thank the University of Alaska Anchorage for funding this work.
Cash, J., Wailes, G.H., & Hopkinson, J. (1905-1921) The British Freshwater Rhizopoda and Heliozoa Ray Society, London.
Deflandre, G. (1936) Etude monographique sur le genre Nebela Leidy. Annales de Protistologie, 5, 201-286.
Heinis, F. (1914) Die Moosfauna Columbiens: in: Voyage d’exploration scientifique en Colombie. Mémoires de la Société Neuchateloise des Sciences Naturelles, 5, 675-730.
Lüftenegger, G., Petz, W., Berger, H., Foissner, W., & Adam, H. (1988) Morphologic and Biometric Characterization of 24 Soil Testate Amebas (Protozoa, Rhizopoda). Archiv für Protistenkunde, 136, 153-189.
Meisterfeld, R. (2000). Order Arcellinida Kent, 1880. In The illustrated guide to the protozoa (eds J.J. Lee, G.F. Leedale & P. Bradbury), Vol. 2, pp. 827-860. Society of protozoologists, Lawrence, Kansas, USA.
Penard, E. (1902) Les Rhizopodes du bassin du Léman Kündig, Genève.
Schönborn, W., Petz, W., Wanner, M., & Foissner, W. (1987) Observations on the morphology and ecology of the soil-inhabiting testate ameba Schoenbornia humicola (Schonborn, 1964) Decloitre, 1964 (Protozoa, Rhizopoda). Archiv für Protistenkunde, 134, 315-330.
Wailes, G.H. (1913) Freshwater Rhizopoda from North and South America. Journal of the Linnean Society of London, Zoology, 32, 201-218.