Centropyxis Stein, 1857 (ref. ID; 3693) or 1859 (ref. ID; 3686)
Synonym; Echinopyxis Claparede & Lachmann, 1859 (ref. ID; 3693); Homoeochlamys Ehrenberg, 1871 (ref. ID; 3693)

[ref. ID; 1618]
Test circular, ovoid, or discoid; aperture eccentric, circular or ovoidal, often with a lobate border; with or without spines; cytoplasm colorless; pseudopodia digitate; fresh water. (ref. ID; 1618)

[ref. ID; 1923]
Aperture rounded or angular; shell mostly membranous with encrusted foreign particles, or covered with sandy material. (ref. ID; 1923)

[ref. ID; 3686]
Shell colourless, yellow or brown; circular, hemispherical or ovoid; in lateral view rounded posteriorly and tapering toward the anterior edge, which often has a recurved margin, conical spines sometimes present at lateral margins; surface either punctated or rough; wall composed of either numerous alveoli arranged in layers or agglutinated mineral particles; aperture sub-terminal or occasionally central, circular or oval and invaginated. (ref. ID; 3686)

Centropyxis aculeata (Ehrenberg, 1830) (ref. ID; 3686) reported year? (ref. ID; 2068, 2329)
Description; The shell is yellow or brown, ovoid or circular and usually has about four or more lateral spines. In lateral view it is spherical and tapers towards the aperture. The shell surface is rough, except for a smooth region around the aperture, and is often covered with sand grains or diatom frustules. Specimens culture in the absence of extraneous particles produce a shell that is proteinaceous and similar in structure to species of Arcella. The aperture is invaginated, oval and sub-terminal. Cash (1905) observed that specimens appear to differ widely from the type description and also from each other in size and structure. Deflandre (1929) in his review of the genus described three varieties of C. aculeata which differ in size, shape and the number of spines. In colonal culture both large and many spined specimens are produced, but these forms represent only a small percentage of the population. (ref. ID; 3686)
Measurements; Length of shell 92-178; breadth of shell 77-137; depth of shell 40-72; diameter of aperture 35-70 um (n = 20). (ref. ID; 3686)
Centropyxis aculeata (Ehrenberg, 1830) Stein, 1859 (ref. ID; 1315, 1335, 2100, 2110, 2143) or Stein, 1857 (ref. ID; 661, 2441, 3693) reported year? (ref. ID; 1618, 1923, 2081, 2121, 2236, 2258, 2304, 2330, 2456, 2457, 2498, 2505, 2510, 2558, 2564, 2683, 3283, 3595) or Stein (ref. ID; 5034)
Syn; Arcella aculeata Ehrenberg, 1830 (ref. ID; 1315) reported year? (ref. ID; 3693); Arcella aculeata Griffiths & Henerey, 1883 (ref. ID; 1315); Arcella diadema Ehrenberg, 1871 (ref. ID; 1315); Arcellina aculeata Canton, 1842 (ref. ID; 1315); Difflugia aculeata Perty, 1849 (ref. ID; 1315) reported year? (ref. ID; 3693); Echinopyxis aculeata Claparede & Lachmann, 1859 (ref. ID; 1315) reported year? (ref. ID; 3693); Echinopyxis australis Lendenfeld, 1885 (ref. ID; 1315)
Description; Test variable in contour and size; with four to six spines; opaque or semitransparent; with fine sand-grains or diatom shells; pseudopodia sometimes knotted of branching; when encysted, the body assumes a spherical form in wider part of test; granulated, colorless or with green globules. (ref. ID; 1618)
With a row spines at the border. Shell compressed, cap-shaped. Membrane brownish, frequently incrusted with sand grains or diatoms. Spine 2 to 10, rarely more. The animal is very shy, sometimes extending a single pseudopod. Habitat ponds, lakes, marshes, on algae. (ref. ID; 1923)
The spines radiated over at least half the margin of the test. (ref. ID; 2683)
Measurements; Diameter 100-150 um; aperture 50-60 um in diameter. (ref. ID; 1618)
Diameter 120-150 um without the spines. (ref. ID; 1923)
The diameters did not exceed 180 um. (ref. ID; 2683)
Centropyxis acuminata Couteaux & Chardez, 1981 (ref. ID; 2122, 2411 original paper) reported year? (ref. ID; 3710)
Description; This species which has been described from a forest soil humus of French Guyane, must be considered as an intermediate form between C. aerophila and C. cassis. It is distinguished by the shape of the aboral region of the shell which is always pointed by an accumulation of exogenic particles. (ref. ID; 2122)
Measurements; Length 70-100 um. (ref. ID; 2122)
Centropyxis aerophila Deflandre, 1929 (ref. ID; 661, 1401, 1923, 2066, 2067, 2077, 2081, 2083, 2109, 2110, 2146, 2154, 2178, 2235, 2329, 2330, 2441, 2489, 2532, 2538, 3279, 3382, 3686, 4737, 5461) reported year? (ref. ID; 3383, 3595)
Description; Shell of small size, ovoid, in lateral view pear-shaped. Shell chitinous, finely punctate or rough, with or without foreign particles, principally of vegetable origin, hyaline or yellowish, sometimes yellowish-brown. Aperture nearly semicircular or elliptic. A widely distributed and common species, giving in ecologically different media a number of adapted which are morphologically stable. Type living especially among mosses on the trees, length 53-85 um; var. sylvatica Deflandre, on forest mosses, length 68-102 um; var. sphagnicola Deflandre, nearly circular in outline, among Sphagnum, diameter 49-66 um. (ref. ID; 1923)
The shell is yellow or brown, ovoid and flattened in the apertural region. In lateral view the aboral region is spherical but tapers sharply near the aperture to form an apertural rim. The shell surface is usually rough and covered with extraneous material, except around the aperture and apertural rim where the surface is smooth. The aperture is invaginated, oval, and sub-terminal. Variation in the size and shape of the shell and aperture in this species appears to be considerable, for example, when Deflandre (1929) described C. aerophila he also described two varieties C. a. var. sylvatica and C. a. var. sphagnicola. He believed these descriptions were necessary to accommodate those specimens whose dimensions were outside those of the initial description. (ref. ID; 3686)
Measurements; Length of shell 53-72; breadth of shell 44-62; depth of shell 34-47; diameter of aperture 24-34 um (n = 8). (ref. ID; 3686)
Centropyxis aerophila var. sphagnicola Deflandre, 1929 (ref. ID; 1401, 1923, 2048, 2067, 2099, 2109, 2155, 2406, 2441, 2454, 2456, 2564, 3223, 3279, 3382, 4737, 4755, 5461) reported year? (ref. ID; 3595, 3598)
Description; Shell approximately hemispheric, in ventral view nearly circular, some individuals of slightly elliptic shape (in transverse or longitudinal axis). Oral region slightly flattened. Aperture sub-terminal, transverse oval and invaginated. Apertural region smooth, dorsal region rough by agglutinated particles. (ref. ID; 4755)
Centropyxis arcelloides Penard, 1902 (ref. ID; 3693 original paper) reported year? (ref. ID; 1333, 1923, 3595)
Description; With a circular aperture. Shell hemispherical with rounded border. Membrane thin, chitinous with small siliceous plates. Aperture circular, faintly invaginated, about half the diameter of the shell in width. Habitat among moss and Sphagnum. (ref. ID; 1923)
Measurements; Diameter 100-110 um. (ref. ID; 1923)
Centropyxis cassis (Wallich, 1864) (ref. ID; 3686) or (Wallich, 1864) Deflandre, 1929 (ref. ID; 661, 2089, 2109, 2236, 2329, 2330, 2356, 2441, 2564, 3223) reported year? (ref. ID; 3501, 3595)
Description; The shell is brown, ovoid, and in outline the sides are usually parallel becoming semi-circular at the extremities. In lateral view it is spherical in the aboral region and tapers towards the aperture. It is composed of sand grains roughly arranged over most of the shell, except in the apertural region which appears smooth. This smoothness, unlike C. aerophila, is not due to a thick overlying layer of organic cement. The aperture is invaginated, oval, subterminal and has a pronounced rim. (ref. ID; 3686)
Comments; This species is of a similar size to C. aerophila and C. platystoma, but can be easily distinguished from them by its shape and lack of thick cement around the aperture. A variety with spines, C. c. spinifera, is listed by Deflandre (1929). (ref. ID; 3686)
Measurements; The greatest diameter varied between 65 and 75 um. (ref. ID; 2356)
Length of shell 79-117; breadth of shell 57-90; depth of shell 41-63; diameter of aperture 31-49 um (n = 2). (ref. ID; 3686)
Centropyxis constricta (Ehrenberg, 1841) (ref. ID; 3686) reported year? (ref. ID; 2329, 2333, 2489, 3496)
Syn; Arcella constricta Leidy (ref. ID; 2489); Difflugia constricta Leidy (ref. ID; 2489)
Description; The shell is yellow or brown, and ovoid. The aboral region is lateral view is spherical but flattened slightly towards the aperture. The shell is usually smooth on the apertural surface and rough at the aboral region. The aperture is invaginated, circular or oval, sub-terminal and has a semi-circular apertural rim. (ref. ID; 3686)
Comments; Previous descriptions (Penard, 1902; Deflandre, 1929) refer to differences in the shape due to the materials used in constructing the shell. C. constricta is similar to C. aerophila and C. ecronis, but can be readily distinguished from the by the shape and position of the aperture and shell size. (ref. ID; 3686)
Measurements; Length of shell 144-181; breadth of shell 132-148; depth of shell 82-102; diameter of aperture 62-85 um (n = 10). (ref. ID; 3686)
Centropyxis constricta (Ehrenberg) Penard, 1890 (ref. ID; 2330, 2441) or (Ehrenberg) Penard, 1902 (ref. ID; 661, 1923, 2081, 2236) reported year? (ref. ID; 2356, 3595, 3598)
Description; Shell of medium size, more than 100 um, elliptical or ovoid in front view, more or less flattened. Aperture at the border of the shell, eccentric, largely elliptic or nearly circular. Shell covered with closely-set sand grains, giving a grey color to the test. Habitat mosses and Sphagnum. (ref. ID; 1923)
The aboral end of the test carried larger mineral particles than the rest of the test. (ref. ID; 2356)
Measurements; Length 120-150; breadth 75-90 um. (ref. ID; 1923)
The length of the test varied between 90 and 120 um, with a width of 60 to 78 um, and an aperture of approximately 30 x 35 um. (ref. ID; 2356)
Centropyxis discoides Penard, 1890 (ref. ID; 3686) reported year? (ref. ID; 2683) or (Penard, 1890) Deflandre, 1929 (ref. ID; 2042, 2068, 2100, 2109, 2146, 2147, 2152, 2255, 2256, 2356, 2361, 2441, 2457) reported year? (ref. ID; 5034)
Description; The test of generally covered with minute brown particles with diatoms interspersed. The margin of the test was more strongly reinforced with diatoms, including two large frustules of a Eunotia sp. placed almost symmetrically. Wailes (1919) described this species as a variety of C. aculeata, and noted that it often lacked spines. (ref. ID; 2356)
The shell is brown, circular and in lateral view discoid. The apertural surface is usually smooth, whilst the aboral surface is rough and covered with sand grains. Small spines may project from the lateral margins, similar to those of C. aculeata, but they are absent on they are absent on the illustrated specimen. The aperture is invaginated, circular and either central or subcentral. Variation seems to be restricted to the presence or absence of spines, although large specimens are reported by Deflandre (1929). (ref. ID; 3686)
Comments; This species was originally described as a variety of C. aculeata, but Deflandre (1929) recognized it as a separate species. I suspect that this and C. ecornis may be varieties of one species. Both forms are larger than C. aculeata, and in Lake Sonfon they differed only in the presence or absence of a few spines around the edge of the test. Specimens from the main body of the lake had four or five small spines confined to about one third of the margin of the test. (ref. ID; 2683)
Measurements; The diameter was 300 um excluding the small spines. (ref. ID; 2356)
Diameter 210 um. (ref. ID; 2683)
Length of shell 202-240; depth of shell 63-65; diameter of aperture 69-71 um (n = 2). (ref. ID; 3686)
Centropyxis ecornis (Ehrenberg, 1841) (ref. ID; 3686) reported year? (ref. ID; 3496) or (Ehrenberg) Leidy (ref. ID; 1923, 2068, 2147, 2234, 2352, 2356, 2457, 2683, 3223, 3501, 3595)
Syn; Arcella ecornis Ehrenberg (ref. ID; 2352)
Description; Shell of large size, more than 200 um, discoidal or largely elliptical, mostly irregular in outline. Shell covered with quartz sand grains; color usually grey, sometimes brownish. Aperture circular or irregularly lobed, not very much eccentric. Habitat only open water, among plants or mosses. (ref. ID; 1923)
The shell is brown and usually circular. In lateral view the aboral region is spherical and tapers from the mid-body position to the apertural lip. The shell is rough, although the apertural surface usually has a covering of organic cement overlying the irregular mineral particles. The aperture is invaginated, oval or circular, sub-terminal with a thick apertural rim. Variation in this species appears to be restricted to size and shape (Deflandre, 1929). (ref. ID; 3686)
Measurements; Greatest diameter 200-275 um. (ref. ID; 1923)
Diameter 280-316 um. (ref. ID; 2356)
The maximum diameter was generally about 211 um. (ref. ID; 2683)
Length 112-128 um. (ref. ID; 3496)
Length of shell 199-262; breadth of shell 182-254; depth of shell 82-116; diameter of aperture 72-98 um (n = 5). (ref. ID; 3686)
Centropyxis ecornis var. deflandrei Thomas, 1957 (ref. ID; 4860) reported year? (ref. ID; 2048)
Description; The shell of this variety differs from Centropyxis ecornis typica by shell size and by a very various aperture shape (circular, polygonal, hexagonal, etc.). (ref. ID; 4860)
Measurements; Length of the shell 88-94 (91 +/- 3), width of the shell 85-90 (87.5 +/- 2.5), height of the shell 45-52 (48.5 +/- 3.5), aperture of the shell 22-30 x 12-19 (26 +/- 4 x 15.5 +/- 3.5) um (n = 25). (ref. ID; 4860)
Centropyxis elongata (Penard, 1890) Thomas, 1959 (ref. ID; 4755, 5461) or (Penard) Thomas, 1959 (ref. ID; 2048, 2089, 2110, 2160, 2420)
Description; Shell in ventral view elliptic, elongated, aperture sub-terminal, oval. Apical region laterally flattened. Surface covered with irregular xenosomes. Nucleus with a central nucleolus. (ref. ID; 4755)
Centropyxis eurystoma Deflandre (ref. ID; 2683, 3595)
Measurements; The diameter of the test was 59 um and the diameter of the centrally placed pseudostome was 23 um. (ref. ID; 2683)
Centropyxis gasparella Charedez & Beyens, 1988 (ref. ID; 4763 original paper) reported year? (ref. ID; 2818)
Description; Shell globular or very slightly oval in apertural view; regularly inflated in lateral view, slightly compressed at the dorsal anterior part. The shell has a greenish tint, and is composed of small polymorphous mineral particles, cemented onto an organic matrix. The aboral region of the shell mostly bears a few mineral particles of larger size. The structure of the aperture is the most striking feature of this species. The wall of the aperture form a trapezium, from which originate two broad internal extensions, which are perforated by two oval openings. These extensions reach the dorsal inner part of the shell, in which they are incorporated. Situated in front of this aperture, an +/- oval depression can be observed. Together with the aperture it forms the characteristic key-hole structure. (ref. ID; 4763)
Etymology; This species is named after Prof. Dr. Ir. Ch. Gaspar, head of the Laboratory of Zoology, Gembloux. (ref. ID; 4763)
Type locality; Centropyxis gasparella sp. nov. has been found in 6 samples; 5 of this originate from small to medium sized ponds, situated in different types of sedge moss meadows (senu Muc & Bliss 1977) in both lowlands and living on the sediment and between submerged aquatic mosses. The sixth sample represented a wet moss habitat. (ref. ID; 4763)
Measurements; Length of shell 100-110: breadth of shell 95-105: depth of shell 40-44 um (n = 15). (ref. ID; 4763)
Centropyxis gasparella var. corniculata Beyens & Chardez, 1997 (ref. ID; 2818 original paper)
Description; The overall morphology, dimensions and the internal structure of the region near the aperture are the same as in Centropyxis gasparella Chardez & Beyens. This new variety has long, thin spines, closed at the apex. They are positioned rather high on the posterior side of the shell. Their number varies from 1 to 5. (ref. ID; 2818)
Measurements; Length of shell 100-125; diameter of shell 99-106; depth of shell 40-45; length of spines 24-35; diameter of aperture X: 28-32, Y: 14-19, Z: 2-16, Z': 15-26 um. (ref. ID; 2818)
Centropyxis hemisphaerica (Barnard) Wailes (ref. ID; 1923, 3595)
Description; With spines irregularly distributed on the dome of the shell. Shell almost hemispherical but asymmetric. (ref. ID; 1923)
Diagnosis; This species differs from C. aculeata having in lateral view a much higher shell. 6 to 12 large horns, 20-42 um in length. Habitat aquatic vegetation. (ref. ID; 1923)
Measurements; Diameter 140-160 um without the spines. (ref. ID; 1923)
Centropyxis hirsuta Deflandre, 1929 (ref. ID; 2066, 2068, 2109, 2151, 2304, 2356, 2361, 3686) reported year? (ref. ID; 3595)
Description; Mineral particles were sparse or absent from the test, which had a scabrous appearance. (ref. ID; 2356)
The shell is colourless, yellow or brown, usually circular and has several lateral spine. In lateral view it is spherical and tapers rapidly at the apical region. There are two lateral pores or indentations situated on a level with the anterior margin of the aperture. The aperture is invaginated, oval, sub-terminal and has a distinct posterior margin. (ref. ID; 3686)
Measurements; Diameter without the spines; 55 um. (ref. ID; 2356)
Length of shell 72-85; breadth of shell 81-87; depth of shell 44-51; diameter of aperture 33-50 um. (ref. ID; 3686)
Centropyxis impressa (Daday, 1905) (ref. ID; 2356)
Description; The aperture had eight shallow lobes. (ref. ID; 2356)
Measurements; Diameter 417 um. (ref. ID; 2356)
Centropyxis kahli Deflandre (ref. ID; 2356)
Measurements; The diameter of the test was 90 um, the height was 60 um, and the diameter of the aperture was 28 um. (ref. ID; 2356)
Centropyxis minuta Deflandre, 1929 (ref. ID; 2067, 2154, 2160, 2178, 2329, 2356, 2457, 2538, 2539, 2541, 2558, 2564, 2683, 3223) reported year? (ref. ID; 3595)
Measurements; Diameter 58 um. (ref. ID; 2356)
The diameter of the test was 32 um and the diameter of the pseudostome was 16 um. Decloitre (1953, see ref. ID; 3595) found test diameters ranging between 19 and 40 um in various African localities. (ref. ID; 2683)
Centropyxis orbicularis Deflandre, 1929 (ref. ID; 1401, 2066, 2160, 2420, 3279, 4737, 4755) reported year? (ref. ID; 3595)
Description; Shell hemispheric, brownish. Aperture in contrast to Plagiopyxis callida widely open, nearly semicircular. The separation between C. orbicularis and P. callida is difficult only in oblique view, in which case even P. callida seems to have an open aperture. (ref. ID; 4755)
Measurements; Deflandre (1929) and Bonnet and Thomas (1960) give 100-140 um for the diameter and 70 and 50-95 um for the depth, respectively. (ref. ID; 4755)
Centropyxis plagiostoma Bonnet & Thomas, 1955 (ref. ID; 2034, 2066, 2087, 2238, 3279, 5461) reported year? (ref. ID; 2021, 3383, 3710)
Description; Shell almost circular in ventral and dorsal view, usually slightly broader than long, about half as deep as broad, anterior portion more distinctly flattened than posterior; greyish or colourless, not transparent; composed of flat quartz particles more rough on posterior and dorsal than on ventral surface, which appear rather smooth and covered by thin organic layer. Pseudostome in anterior half of ventral surface, i.e. excentric, transverse-elliptical to almost circular, with irregular edge often completely or partially covered by knobby quartz particles ("dents"); distinctly invaginated, preoral portion abruptly curved, postoral surface flat and gradually inclined. (ref. ID; 2034)
Centropyxis plagiostoma var. oblonga Chardez, 1962 (ref. ID; 2021, 2034)
Measurements; Length 80-85 um. (ref. ID; 2034)
Centropyxis platystoma Penard, 1890 (ref. ID; 3686) or (Penard, 1890) Deflandre, 1929 (ref. ID; 661, 1401, 2066, 2081, 2109, 2304, 2361, 2441) reported year? (ref. ID; 3501, 3595, 3598)
Description; The shell is yellow or brown, oval or elongate, and often has a constriction at the aperture to form a neck. In lateral section it is spherical aborally and flattened in the apical region. The shell surface is usually rough, but has a smooth apertural rim. The aperture is invaginated, circular, and sub-terminal. There appear to be three major areas of variation in this species, the degree of invagination of the aperture, the constriction of the neck and the shape of the shell (Deflandre, 1929). (ref. ID; 3686)
Measurements; Length of shell 62-81; breadth of shell 34-48; depth of shell 25-31; diameter of aperture 19-27 um (n = 8). (ref. ID; 3686)
Centropyxis platystoma var. armata Deflandre (ref. ID; 3496)
Measurements; Length 80-118 um. (ref. ID; 3496)
Centropyxis pontigulasiformis Beyens, Chardez & De Bock, 1986 (ref. ID; 2122 original paper, 2555)
Description; The shell is formed of two distinct parts: the shell body, and a rather large semi-circular visor. The body is perfectly spherical and is perforated by a small circular aperture. The shell wall is composed of an organic matrix, incorporating fine plate-like polymorphous mineral particles. The visor which expands fan-like above and around the aperture, is mostly embossed with more voluminous quartz particles, in particular at the rim. Seen from an apertural view, this visor is as large as the shell body. (ref. ID; 2122)
In the test two parts may be distinguished: the rear spherical brown coloured part which is covered with fine xenosomata embedded in the matrix and the front flat part with a circular aperture. The front part is covered with large xenosomata which project from the surface of the test. In Opravilova individuals, unlike the original description, the aperture was larger. (ref. ID; 2555)
Measurements; Diameter of shell 58-62, diameter of the aperture 8-10, length of the visor 24-28, total length 82-90 um (n = 5). (ref. ID; 2122)
Length of the test 91-102; width of the test 58-62; diameter of the aperture 36 um. (ref. ID; 2555)
Centropyxis spinosa Cash, 1905 (ref. ID; 3686) or (Cash) Deflandre, 1929 (ref. ID; 2441) reported year? (ref. ID; 2683, 3595)
Description; All specimens had pale amber chitinous tests, lacking mineral particles, but with a few diatom frustules. Most specimens had four spines, ranging up to 40 um in length. (ref. ID; 2683)
The shell is yellow or brown, ovoid or circular and has about six lateral spines. In lateral view it is spherical but tapers towards the apical region. The shell surface is usually rough and covered with sand grains or diatom shells, whilst the area around the aperture is smooth. This latter region is occasionally encrusted with extraneous matter, but usually shows the organic matrix of the shell. The aperture is invaginated, oval or uneven in outline, has two lateral internal extensions that divide the opening, and is excentric in position. (ref. ID; 3686)
Comments; Cash (1905) suggested that this species differs from C. aculeata in the structure of the shell, being delicate, more compressed, with more spines and having a lobate aperture. This species appears to vary like C. aculeata in the number of spines and the size of the shell, but is easily distinguished by the internal extensions of the aperture. (ref. ID; 3686)
Measurements; The diameters of the tests ranged from 97 to 127 um, and the pseudostomes from 38 to 48 um. (ref. ID; 2683)
Length of shell 105-141; breadth of shell 84-137; depth of shell 34-45; diameter of aperture 27-51 um (n = 7). (ref. ID; 3686)
Centropyxis stellata Wailes (ref. ID; 1923)
Description; With a stellate aperture. Shell nearly hemispherical in side view. A large species, circular in oral view; test composed or irregularly-shaped siliceous plates, without protuberances. Animal not observed. Habitat spring and stream. (ref. ID; 1923)
Measurements; Diameter 335-400 um. (ref. ID; 1923)
Centropyxis sylvatica Deflandre, 1929 (ref. ID; 4737), (Deflandre, 1929, var.) Bonnet and Thomas, 1955 (ref. ID; 4755, 5461) or (Deflandre) Thomas, 1955 (ref. ID; 661, 2087, 2110, 2121, 2238, 2441, 2456, 2457, 2482, 2555, 2852, 3279)
See; Centropyxis aerophila
Description; Shell very similar to C. aerophila and C. aerophila var. sphagnicola. Apertural region, however, separated from the rest of the shell by a perforated diaphragm. (ref. ID; 4755)
Measurements; The dimension of the aperture varies most; the other parameters vary 7-10% round about the mean. (ref. ID; 4755)