Nannoplankton | plankton 2-63 µm in diameter. (Alternative spelling nanoplankton, see appendix). Informal grouping including coccolithophores, Thoracosphaera, chrysophytes, etc., but excluding the bacterial picoplankton. {Lohmann 1909} |
Calcareous nannoplankton | nannoplankton with calcareous tests.{?Stradner 1961} |
Nannofossil | fossil <63 µm in diameter, excluding fragments and juveniles of larger fossils. |
Calcareous nannofossil | nannofossil formed of calcium carbonate. |
Coccolithophore | noun, calcareous nannoplankton belonging to the division Haptophyta {Lohmann 1902} |
Coccolithophorid | adjective, e.g. Coccolithophorid algae. |
Coccosphere | test of coccolithophore (not necessarily spherical). An extracellular cover made up of numerous coccoliths. {Wallich 1860} |
Coccolith | calcareous structure formed by coccolithophore. {Huxley 1868} |
Haptophyte | unicellular alga belonging to the division Haptophyta, includes all coccolithophores, and also related non-calcifying forms, e.g. Prymnesium, Phaeocystis, Pavlova, Chrysochromulina (Alternative term Prymnesiophyte, see appendix). |
Nannolith | calcareous nannofossil lacking the typical features of calcareous dinophytes, heterococcoliths or holococcoliths and so of uncertain affinity, see also Young (1992a), Young et al. (1994, 1999). The division between coccoliths and nannoliths varies between authors and is liable to revision as new data becomes available. N.B. This rather restricted definition of the term has little etymological justification, but has been widely used, e.g. Perch-Nielsen (1985a, 1985b), Bown (1987), Aubry (1989). (The terms heliolith and ortholith provide an alternative basis for sub-dividing the calcareous nannofossils, see appendix). {?Perch-Nielsen 1985a} |
Heterococcolith | coccolith formed of crystal-units of variable shape and size. Crystal units typically arranged in cycles with radial symmetry. {Braarud et al. 1955a, 1955b} |
Heterococcolithophore | cell bearing coccosphere of heterococcoliths. |
Holococcolith | coccolith formed of numerous minute (<0.1 µm) crystallites all of similar shape and size (N.B. Many of the terms below are not applicable to holococcoliths, and there is a separate section for specific holococcolith terms). {Braarud et al. 1955a, 1955b} |
Holococcolithophore | cell bearing coccosphere of holococcoliths. |
Combination coccosphere | coccosphere with both hetero- and holococcoliths. N.B. These are thought to represent a transitional state between heterococcolithophorid and holococcolithophorid phases of the life cycle. (The alternative term combination cell is less precise so is not now recommended). {Thomsen et al. 1991, Cros et al. 2000} |
Xenosphere | anomalous coccosphere containing coccoliths normally regarded as forming on quite discrete species (e.g. Emiliania huxleyi and Gephyrocapsa oceanica; Winter et al. 1979). N.B. These are very probably artefacts, the term is suggested specifically to suggest the abnormal nature of these structures. See also Young & Geisen (2002). {Young et al. 1997, from Greek xenos, stranger} |
Monomorphic | all coccoliths of similar type (e.g. Coccolithus). |
Dimorphic | coccoliths of two discrete types (e.g. Scyphosphaera). |
Polymorphic | coccoliths of more than two discrete types (e.g. Syracosphaera pulchra). |
Varimorphic | coccosphere with coccoliths whose size and/or morphology varies according to position on the coccosphere (e.g. Helicosphaera). {Young et al. 1997} |
Dithecate | with two discrete layers of coccoliths of different types (e.g. Syracosphaera pulchra). |
Endotheca | inner layer of coccoliths of dithecate coccosphere. |
Exotheca | outer layer of coccoliths of dithecate coccosphere. |
Monothecate | with a single layer of coccoliths (e.g. Scyphosphaera). |
Multilayered | with two or more layers of coccoliths but no differentiation into endo- and exotheca (e.g. Emiliania, Florisphaera, Coccolithus pelagicus phase hyalinus). |
Shape | coccospheres are three-dimensional so their shape should be described using appropriate terms for solid objects. Useful terms include: cylindrical, ellipsoidal, fusiform (elongate with tapering ends), obpyriform (inverse pear-shaped), ovoid (egg-shaped, i.e. one end broader than the other), spherical. See also Heimdal (1993), Jordan et al. (1995). |
Apical pole | end of coccosphere with flagellar opening. |
Antapical pole | opposite end of coccosphere. |
Antapical coccoliths (abb. AAC) | coccoliths occurring at antapical pole. |
Body coccoliths (abb. BC) | coccoliths other than polar coccoliths and exothecal coccoliths. |
Circum-flagellar coccoliths / apical coccoliths (abb. CFC) | coccoliths occurring around flagellar opening. (Alternative term stomatal coccoliths, see appendix). |
Exothecal coccoliths (abb. XC) |
coccoliths of the exotheca |
Flagellar opening | opening in coccosphere through which the flagella and haptonema pass. |
Polar coccoliths | coccoliths occurring at poles of coccospheres. {Kamptner 1937} |
Overlapping | adjacent coccoliths overlap. |
Non-overlapping | adjacent coccoliths arranged with edges directly butting rather than overlapping. |
Interlocking | adjacent coccoliths interlock. |
Non-interlocking | adjacent coccoliths do not interlock. |
Proximal | directed toward centre of coccosphere/cell. On nannofossils this is usually assumed to be the concave side, but cannot always be determined. |
Distal | directed toward outer surface of coccosphere/cell. |
Horizontal | perpendicular to proximo-distal direction. |
Vertical | proximo-distal direction. |
Internal/inner/inward | toward centre of coccolith. |
External/outer/outward | away from centre of coccolith. |
Longitudinal | direction parallel to long axis of an elliptical / elongated coccolith. |
Transverse | direction parallel to short axis of an elliptical / elongated coccolith. |
End | edge of coccolith parallel to short axis. |
Side | edge of coccolith parallel to long axis. |
Length/width/height | maximum dimensions of coccoliths in the longitudinal, transverse and vertical directions respectively. |
Central-area | Inner part of coccolith, enclosed by the rim. Usually characterised by less regularly cyclical elements than the rim and by inward element growth. May be entirely closed, or include a central opening. N.B. We recommend hyphenating central-area since it has a special meaning. |
Rim | Outer part of coccolith, usually characterised by regular cycles, some vertically directed structures and outward element growth (alternative term marginal area, see appendix). N.B. Use of this term was agreed after considerable discussion at the workshops. |
Planolith | rim not elevated (e.g. Rhabdosphaera, Discoaster). {Young 1992a, from Latin planus flat} |
Murolith | rim elevated but without well developed shields (e.g. Zeugrhabdotus, Pontosphaera). (Discolith has been used in this sense, see appendix). {Young 1992a, from Latin murus wall} |
Placolith | rim has two, or more, well developed shields (e.g. Coccolithus). {Lohmann 1902} |
Axial Ratio (abb. AR) | ratio of length to width. Suggested descriptive terms, for elliptical coccoliths, are: Circular ; Sub-circular; Broadly elliptical; Normally elliptical; Strongly elliptical.. |
Asymmetrical | without bilateral symmetry due to a wing or similar structure. |
Elliptical | continuously curved with two axes of symmetry. Close to, but not necessarily an exact, mathematical ellipse (alternative terms oval, ovoid, see appendix). |
Irregularly elliptical | with an approximately elliptical shape but departing noticeably from regular form. |
Lenticular | symmetrical form intermediate between a rhombus and ellipse, i.e. with pointed ends (e.g. Syracosphaera prolongata, Stradnerlithus). |
Oblong | symmetrical form intermediate between a rectangle and ellipse, i.e. with curved ends but sub-parallel sides (e.g. Calciopappus caudatus, Ellipsolithus macellus). N.B. This is recommended botanical use (Stearn 1983). |
Polygonal | with straight sides (triangular, pentagonal etc., e.g. scapholiths, Corollithion). (alternative term geometric, see appendix). |
Reniform | concavo-convex, kidney-shaped (e.g. Nephrolithus). |
Ring-shaped | circular or elliptical with narrow rim and open central-area (e.g. Cricosphaera, Manivitella). |
Wing | local extension of rim (e.g. Helicosphaera, Kamptnerius). |
Caneolith | Syracosphaeraceae, endothecal coccolith. (N.B. The terms complete/incomplete caneoliths have been used, see appendix). {Braarud et al. 1955a, 1955b} |
Cricolith | Pleurochrysidaceae, placolith with narrow rim and open central-area . {Braarud et al. 1955a, 1955b} |
Cyrtolith | Syracosphaeraceae, exothecal coccolith. {Braarud et al. 1955a, 1955b} |
Discolith | Pontosphaeraceae, murolith without flanges. {Huxley 1868} |
Helicolith | Helicosphaeraceae, coccoliths with helical flange. |
Lopadolith | high rimmed equatorial murolith of Scyphosphaera. {Lohmann 1902} |
Osteolith | whorl coccoliths of Ophiaster. {Halldal and Markali 1955} |
Pappolith | Papposphaeraceae. |
Podorhabdid coccolith | Podorhabdaceae. |
Protolith | Stephanolithaceae, Parhabdolithaceae (cf. Bown 1987). |
Rhabdolith | Rhabdosphaeraceae, planoliths +/- spines. {Schmidt 1870} |
Scapholith | Calciosolenia, Anoplosolenia. (Alternative term rhombolith). {Deflandre and Fert 1954} |
Tremalith | Hymenomonadaceae, vase-shaped murolith. {Lohmann 1913} |
Reticulofenestrid coccolith | Reticulofenestra and descendants. {Young 1989} |
Coccolithid placolith | Coccolithaceae. {Jordan et al. 1995} |
Element | Apparently discrete component of a coccolith. This is an observational term, several elements may unite to form a crystal-unit. |
Crystal unit | A group of elements from different cycles in crystallographic continuity. These are the fundamental components of coccoliths and their identification is a key objective of ultrastructural research. |
Segment | one symmetrically repeated part of the coccolith, including elements from each cycle, consisting of one or more crystal-units. |
Lamina | platy sub-structure within a crystal-unit (e.g. Braarudosphaera). |
Contact-surface | plane of contact between two elements. (alternative term attachment surface, see appendix). |
Suture | trace of contact-surface on surface of coccolith. |
Cycle | ring of elements or crystal-units. |
Tier | one of a set of vertically superposed cycles (e.g. Arkhangelskiella, Lapideacassis). |
Block | nearly equidimensional element (a≈b≈c). |
Tile | broad and thin element (a≈b>c) N.B. Plate has been used in this sense but we prefer to use it for larger structures, not for single elements). |
Lath | elongate and wide element(a>b>c). |
Rod | elongate and narrow element (a>b≈c) |
Wedge | tapering nearly equidimensional element. |
Petal/petaloid element | tapering broad and thin element. |
Ray | tapering elongate and wide element. |
Spine | tapering elongate and narrow element. |
Granule | small and irregular or variable-shaped element (e.g. blanket elements of Helicosphaera, spine-forming elements of Cretarhabdus). N.B. Crystallite has been used in this sense but we prefer to only use it for holococcolith elements. |
Curvature | curving of elements. Laevogyre - elements curve to the left when traced radially outward. Dextrogyre - elements curve to the right when traced radially outward. Straight - elements not curved. |
Node | block-shaped projection from element. |
Keel | lath-shaped projection from element. |
Ridge | rod-shaped projection running along element. |
Tooth | rod or wedge-shaped projection from element. |
Kink | angular bend in element. |
Offset | displacement of an element from radial growth due to a double kink. |
Scissor-structure | crystal-unit structure formed of two elements growing at only slightly different angles, and forming a two-layered shield (e.g. Coccolithus upper and lower proximal shield elements, Fig. 6) or tube (e.g. Toweius inner and outer tube elements, Fig. 6). {Young 1992b} |
Cross-over zone | belt around which two cycles of crystal-units cross (this usually corresponds to the proto-coccolith ring, e.g. Coccolithus, Fig. 6). {Young 1992b} |
Canal | narrow elongate opening within a coccolith or nannolith (Fig.s. 10, 14). |
Cavity | broad opening within a coccolith or nannolith (Fig.s. 10, 14). |
Common opening | opening formed by several individuals; i.e. the space within a coccosphere or group of associated nannoliths. |
Depression | pit on the surface of a coccolith or nannolith. |
Hole | opening running through one element (e.g. Pemma basquensis). {Farinacci et al. 1971} |
Opening | general term for any space not filled by elements. |
Perforation | small opening between two or more elements. {Farinacci et al. 1971} |
Slit | elongate perforation (e.g. Emiliania). |
Shield | broad (sub-)horizontal structure (placoliths). |
Tube | (sub-vertical structure between two shields (placoliths). |
Wall | (sub-)vertical structure not associated with shields (muroliths). |
Flange | (sub-)horizontal protrusion from rim. |
Collar | (sub-)vertical protrusion from rim (may occur on proximal or distal surface). |
Crown | discontinuous/beaded collar. |
Radial | direction in the surface of the baseplate perpendicular to its margin: Inward-outward - toward-away from centre. | |
Tangential | direction in the surface of the baseplate parallel to its margin: Clockwise/dextral/right, anticlockwise/sinistral/left senses of direction as seen in distal view. We recommend: use of clockwise/anticlockwise as the clearest of these terms for general purposes. Use of dextral/sinistral when it is wished to particularly emphasise that this is the orientation as seen in distal view. | |
Vertical | direction perpendicular to the baseplate: Up/down distal-proximal directions. | |
Flare and taper | divergence of orientation from horizontal/vertical in the radial direction. Flare surfaces diverge upward, producing obconical/funnel-shaped bodies. Taper surfaces converge upward, producing conical bodies. |
Imbrication/inclination | divergence from horizontal in the tangential direction. Imbrication is applicable to a cycle of elements, inclination to individual elements. |
Clockwise/anticlockwise imbrication | offset of upper part of element from lower. |
Imbrication angle | angle of contact-surface from the horizontal. High-angle - sub-vertical contact-surfaces. Low-angle - sub-horizontal contact-surfaces. |
Zeugoid rim | rim with high-angle imbrication, and without distinct shields. (Alternative terms loxolith rim, zygodiscid rim, see appendix). |
Obliquity | horizontal divergence from radial direction. (Alternative term precession, see appendix). |
Dextral/sinistral obliquity | deflection from radial of outer part of element relative to inner part, as seen in distal view. Note that elements will show opposite apparent senses of obliquity in distal and proximal view. This can be described as follows: a dextrally oblique cycle displays clockwise obliquity in distal view but anti-clockwise obliquity in proximal view. |
Butting | elements with simple (sub-)radial sutures. |
Interlocking | elements with complex sutures. |
Overlapping | elements with low angle oblique sutures (N.B. This pattern has occasionally been described as imbrication, but we prefer to use imbrication for description of vertical structures). |
Conjunct | formed from crystal-units of the rim structure. E.g. Gephyrocapsa (bridge and grill), Helicosphaera sellii (bar), Kamptnerius (plate), Watznaueria biporta (bar). (Alternative term optically continuous structure, see appendix). {Young 1992a} |
Disjunct | formed from crystal-units discrete from the rim structure. E.g. Arkhangelskiella (plate), Coccolithus pelagicus (bar), Helicosphaera seminulum (bar), Watznaueria britannica (bar). (Alternative term optically discontinuous structure, see appendix). {Young 1992a} |
Basal | occurring on the proximal surface. |
Elevated | occurring above the proximal surface. |
Vaulted | cone-shaped, rising from the rim toward the centre. |
Longitudinal | parallel with long axis of (elliptical) coccolith. |
Planar | flat, not vaulted. |
Transverse | parallel with short axis of (elliptical) coccolith. |
Diagonal | inclined relative to axes. Angle should be measured from transverse direction (but some authors use opposite convention, i.e. measure angle from longitudinal direction): Low angle near to transverse direction; High angle near to longitudinal direction. |
Dextral/sinistral | inclined to the right/left of the long-axis as seen in distal view. N.B. As with element obliquity the terms dextral/sinistral are preferred for describing orientations which appear different in proximal and distal view. |
Relative width | width of central-area relative to rim width: Wide central-area width >2x rim width; Normal central-area width 1-2x rim width; Narrow central-area width <1x rim width. |
Arm | part of crossbar, bridge or cross running from centre of coccolith to edge of central-area. (alternative terms limb, spoke, see appendix). |
Bar | any elongate central-area structure. N.B. This is a general term. When it is useful to be more specific terms such as longitudinal bar, cross-bar, and arm can be used. (Alternative term jugum, see appendix). |
Blanket | covering of small elements on distal side of central-area (e.g. Helicosphaera, Coccolithus). |
Bridge | elevated bar spanning the central-area (e.g. Gephyrocapsa). |
Cross-bar | bar spanning the central-area. |
Cross | pair of cross-bars meeting in centre. Axial cross (abb. +), cross-bars longitudinal and transverse. Diagonal cross (abb. X) cross-bars diagonal - may be symmetrical or asymmetrical relative to the axes. Offset cross cross with an offset between the arms of one, or both, of the crossbars (e.g. Chiasmolithus). |
Foot | broadening of bar as it meets the rim (e.g. Cruciplacolithus tenuis). |
Lateral bar | bar running from rim to a cross bar (e.g. Retecapsa). |
Central opening | opening at centre of coccolith, may be spanned by bars or other central-area structures, but not by a continuous structure such as a grill or plate. |
Closed central-area | central-area without a central opening. |
Grill | system of bars closing central-area (e.g. Emiliania). |
Net | mesh-like structure closing central-area (e.g. Reticulofenestra, Cribrosphaerella). (Alternative term cribrate central-area, see appendix). |
Open central-area | central-area without any structures. |
Plate | continuous or nearly continuous structure closing central-area. |
Perforated plate | plate with perforations (e.g. Arkhangelskiella). |
Calyx | flaring structure at tip of process (e.g. Podorhabdus, Papposphaera). |
Boss | low process, height similar to or less than width (alternative term knob, see appendix). |
Process | general term for any structure rising from the central-area. |
Protrusion | broad low process, with height similar to width, and width near that of entire central-area. Types: Conical cone-shaped protrusion (e.g. Acanthoica); Sacculiform sac-like protrusion with more or less rounded upper part (e.g. Algirosphaera). (N.B. labiatiform has been used for the elongate double-lipped sacculiform protrusions, see appendix). |
Spine | elongated process, height greater than width. (Alternative term column, see appendix). Types: Styliform {Halldal and Markali 1955} - spine tapers toward the distal end; Claviform {Halldal and Markali 1955} - spine has blunt end, without calyx. (N.B. helatoform has been used for nail-shaped processes, see appendix); Calicate spine is surmountd by a calyx. Salpingiform {Braarud et al. 1955a, 1955b} - spine (or protrusion) trumpet-shaped (e.g. Discosphaera). |
Stem | part of process below calyx. |
Cavity | wide opening within process (e.g. Podorhabdus grassei, Algirosphaera robusta). |
Canal | narrow opening running along length of process. |
Proximal pore | opening of canal, on proximal side of central-area. |
V-unit | crystal-unit with sub-vertical orientation of c-axis. {Young and Bown 1991} |
R-unit | crystal-unit with sub-radial orientation of c-axis, relative to its point of origin (nucleation) on the proto-coccolith ring. {Young and Bown 1991} |
T-unit | crystal-unit with sub-tangential orientation of c-axis (e.g. Braarudosphaeraceae, Polycyclolithaceae). {Young et al. 1997} |
Compound | formed of several crystal-units. E.g. Micula, Discoaster. |
Pseudo-monocrystalline | formed of several crystal-units with parallel c-axes, but non-parallel a-axes. E.g. Discoaster. These behave optically as single crystals, but will not fuse into a single crystal during overgrowth. |
Monocrystalline | formed of a single crystal-unit, and so all elements have identical crystallographic orientation of c- and a-axes and overgrow as one unit, e.g. apical spine of Sphenolithus heteromorphosus, entire nannoliths of Florisphaera, Marthasterites, Minylitha, Ceratolithus. |
Symbols | A single symbol per element can indicate c-axis direction, see Fig.ure 8. |
Shading | To directly illustrate observations made with a gypsum plate hatching can be used - vertical and horizontal for parts in extinction (purple). Diagonal for birefringent parts (blue and yellow). The direction of diagonal hatching should of course be based on the c-axis orientation and since the gypsum plate orientation varies between microscopes the relationship between observed colour (blue, yellow) and c-axis direction has to be determined for each microscope. |
Unit type shading | For illustrating structure it is convenient to apply the same shading to all the elements of one crystal-unit cycle in all views of the nannolith. For this the following scheme is recommended: V-units stippled; R-units blank; T-units dashes. |
Birefringent/non-birefringent | appearing bright/dark between cross-polars. N.B. A coccolith or part of a coccolith can only appear non-birefringent in one orientation (when the c-axis is vertical), so these terms should not be used without explicit description of specimen orientation; e.g. "discoasters are non-birefringent in plan view". |
Extinction-figure | appearance of a specimen in cross-polarized light, particularly pattern of isogyres. |
Isogyre | dark line in cross-polarized light caused by elements in extinction. |
North/South, East/West | orientations relative to the microscope body. |
Normally formed | with typical form. |
Abnormally formed | departing from normal form in some way, includes all the categories below. |
Coccolithogenesis | process of coccolith development and growth {Outka and Williams 1971} |
Proto-coccolith ring | earliest stage of coccolith growth, crystal-units simple without differentiation of elements. {Young 1989} |
Incomplete coccolith | elements differentiated but incompletely grown. |
Complete coccolith | all elements fully grown. |
Under-calcified | coccolith with elements markedly thinner than normal for the species. |
Normally calcified | coccolith with elements of normal thickness for the species. |
Over-calcified | coccolith with elements markedly thicker than normal for the species. |
Overgrowth | secondary inorganic growth of calcite on elements. |
Etching | secondary inorganic dissolution of calcite from elements. |
X | Excellent preservation | coccoliths appear pristine. |
E1 | Slight etching | serrate outlines, partial dissolution of delicate structures. |
E2 | Moderate etching | irregular outlines, dissolution of most delicate structures and species. |
E3 | Strong etching | much material fragmented, only resistant species left. |
O1 | Slight overgrowth | overgrowth of shield and central-area elements noticeable but does not obscure details. |
O2 | Moderate overgrowth | many elements with large overgrowths, many details obscured. |
O3 | Strong overgrowth | only overgrown elements, identifications very limited. |
Dibrachiate | consisting of two sub-parallel arms joined at one end. Includes horseshoe, arrow-head, and arcuate shapes (e.g. Ceratolithus, Amaurolithus, Ceratolithina, Ceratolithoides - except C. verbeekii). |
Compact | more or less equidimensional nannoliths. Includes conical (e.g. Sphenolithus), obconical (i.e. inverted cone-shaped, e.g. Conusphaera), cylindrical (e.g. Fasciculithus) and cubic (e.g. Micula) shapes. |
Rod-shaped | elongate, and apparently without a basal disc. Includes bladed (e.g. Lithraphidites quadratus, Triquetrorhabdulus carinatus) and (sub-)cylindrical (e.g. Microrhabdulus) shapes. |
Radiate | with radial symmetry. N.B. the number of crystal-units may be larger or smaller than the number of rays. |
Triradiate | threefold radial symmetry (e.g. Marthasterites, Trochasterites). |
Tetraradiate | fourfold radial symmetry (e.g. Micula, Quadrum, Nannotetrina). |
Pentaradiate | fivefold radial symmetry (e.g. Goniolithus, Braarudosphaera). |
Multiradiate | more than fivefold radial symmetry (e.g. many Discoaster spp.). |
Central body | core part of radiate nannolith where elements are in contact. |
Free rays | parts of radiate nannolith extending beyond central body. |
Short free rays | length of free rays is less than radius of central body, resulting in a rosette-shaped outline. |
Long free rays | length of free rays is greater than radius of central body, resulting in a star-shaped outline. |
Convex outline | without free rays (e.g. Braarudosphaera). Including e.g. triangular, square, and pentagonal shapes. |
Stellate | with free rays (e.g. Micrantholithus, Discoaster). Including rosette and star-shaped. |
Lamina | plate-like sub-element of segments. |
Segment | one of the five component parts of a pentalith. They appear to be single crystal-units, with tangential c-axis orientation. |
Apex/anterior end | front of dinoflagellate when swimming, usually pointed. Almost always contains the archaeopyle. |
Antapex/posterior end | rear of dinoflagellate when swimming, usually flaring. |
Ventral side | side of dinoflagellate with longitudinal flagellum and sulcus. |
Dorsal side | side opposite longitudinal flagellum and sulcus. |
Calcisphere | hollow, typically spherical, calcareous nannofossil. Whereas coccospheres are composite structures formed of numerous coccoliths calcispheres possess a continuous wall. |
Cyst | wall formed around dinoflagellate during non-motile, non-vegetative, stage. These often show paratabulation but are continuous structures, except for the archaeopyle if present. Most calcispheres are thought to be cysts, however, the thoracosphere of Thoracosphaera heimii is formed during the vegetative stage and so is not a cyst. |
Dinoflagellate | informal taxon-based term for member of the phylum Dinophyta. |
Theca | non-resistant organic wall of motile vegetative stage of dinoflagellates, composite structures formed of plates. |
Thoracosphere | informal taxon-based term for calcisphere formed by Thoracosphaera. N.B. T. heimii has a wall structure of large elements (ca. 1 µm) with their c-axes tangential to the wall, and randomly aligned. |
Oblique/Obliquipithonelloid | formed of elements with their c-axes oblique to the wall and variably aligned relative to each other (e.g. Obliquipithonella multistrata). |
Pithonelloid | formed of elements with their c-axes oblique to the wall and sub-parallel to each other (e.g. Pithonella sphaerica, P.ovalis). |
Radial/Orthopithonelloid | formed of elements with their c-axes perpendicular to the wall (e.g. Calciodinellum, Rhabdothorax). |
Tangential | formed of elements with their c-axes tangential to the wall (e.g. Fuetterella conforma, Thoracosphaera heimii). |
Archaeopyle | opening for excystment. |
Operculum | plate covering the archaeopyle. |
Paratabulation | structures on the cyst of a dinoflagellate reflecting the tabulation of the theca. Paratabulation may be developed on the inner or the outer surface of calcispheres. |
Cingulum | sub-equatorial channel occupied by the transverse flagellum. |
Sulcus | furrow occupied by longitudinal flagellum. |
Horn | protrusion from either end of dinoflagellate. |
Holotabulate | paratabulation of ridges or edges on the cyst corresponding to plate boundaries on the theca. |
Intratabulate | paratabulation of processes on the cyst corresponding to plates on the theca. |
Cingulotabulate | paratabulation confined to cingulum and archaeopyle. |
Cryptotabulate | paratabulation confined to archaeopyle. |
Upper / lower | The more-ornamented surface is designated upper. This division is arbitrary, but it is useful since there is a consistent polarity to structures. With careful through-focussing it is quite possible to distinguish the two sides by light microscopy. N.B. The terms distal/proximal should not be used since ceratoliths appear to be either intracellular or wrapped around the cell (Norris 1965). |
Anterior / posterior | Closed end is designated anterior. |
Left /right | Based on upper view, looking toward anterior end. |
Apical region | anterior end of ceratolith, hence terms such as apical node. |
Arch | part of apical region connecting the two arms. |
Arm | rod-like extension back from apical region. |
Rod | rod-shaped structure attached to the nannolith, (e.g. Amaurolithus bizarrus). |
Spur | projection from apical region. |
Keel | lath-like structure running along an arm. Types: Dentate keel - keel formed of sub-parallel teeth. Smooth keel - keel without teeth. |
Tooth | rod-like sub-element of a keel. |
Wing | plate-like extension from main body of nannolith (e.g. Amaurolithus ninae). |
Longitudinal | parallel to length of nannolith. |
Transverse | perpendicular to length of nannolith. |
Blade | one of the three main sub-parts of the nannolith. |
Dentate blade | blade with transverse sub-structure of rod-shaped teeth. |
Lateral blade | one of two broader blades nearly in the same plane (e.g. T. rugosus) |
Median blade | narrowest of three blades. |
Ridge | subsidiary longitudinal structure on a blade. E.g. T. challengeri. |
Wing | blade greatly extended in transverse direction. E.g. T. finifer. |
Tooth | rod-like part of a dentate blade. |
Discoaster | nannolith formed by Discoasteraceae. |
Eu-discoaster | typically Neogene and usually star-shaped discoasters, with planar contact surfaces between elements. |
Helio-discoaster | typically Palaeogene and usually rosette-shaped discoasters, with curved contact surfaces. |
Proximal | Concave side of eudiscoaster |
Distal | Convex side of eudiscoaster |
Laevogyral face | Side of heliodiscoaster showing left-handed curvature of rays |
Dextrogyral face | Side of heliodiscoaster showing right-handed curvature of rays |
Ray | disc element. |
Free ray | part of ray protruding beyond central-area |
Ray tip | outermost part of ray. |
Bifurcate tip | ray tip divides into two bifurcations (e.g. D. variabilis). |
Simple tip | ray tip without bifurcation or proximal extension. |
Proximal extension | continuation of the ray downward from the tip (e.g. D. brouweri). |
Central-area | portion of discoaster with rays in contact. |
Contact-surface | surface between adjacent elements (alternative term attachment surface, see appendix). |
Disc | main part of discoaster, excluding bosses or stems. |
Boss | low distal or proximal protrusion from centre of disc (alternative term knob, see appendix). |
Rosette-shaped | discoaster with short free rays (Text-fig. 10). |
Segment | ray and associated boss or stem elements. |
Stem | high distal or proximal protrusion from centre of disc (e.g. Discoaster kuepperi). |
Star-shaped | discoaster with long free rays (Text-fig. 10). |
Sutural ridge | ridge running along suture. |
Apical cycle | distal cycle of fasciculith. (Alternative term cone, see appendix). |
Central body | optically distinct body occurring in the centre of fasciculith. {Romein 1979} |
Column cycle | proximal cycle of fasciculith, usually forms most of the fasciculith. |
Fenestra | regular depression on fasciculith. |
Longitudinal ridge | ridge parallel to length of fasciculith. |
Proximal surface | lower surface of fasciculith. |
Anterior | end with origin of flange and usually with broader flange on distal side often with distinct wing or spur. (Alternative term pterygal, see appendix). |
Posterior | opposite end to anterior. (Alternative term antipterygal, see appendix). |
Dextral/sinistral | right/left sides of helicolith as seen in distal view with anterior end upwards. As with other uses the terms dextral/sinistral are recommended in place of left/right for terms referring to one particular orientation. The wing, when present is on the sinistral side. |
Bar | structure crossing central opening. Types; |
Conjunct bar | developed from rim elements (e.g. H. carteri). (Alternative terms optically continuous bar, bar, bridge, see appendix). |
Disjunct bar | formed from elements discrete from the rim (e.g. H. intermedia). (Alternative terms optically discontinuous bar, bridge, bar, see appendix). |
Normally oriented bar | diagonal bar with dextral orientation; i.e. rotated to the right of the long axis in distal view/ anterior end on opposite side to the wing. |
Inversely oriented bar | diagonal bar with sinistral orientation; i.e. rotated to the left of the long axis in distal view/ anterior end on same side as wing. N.B. Use of the terms normal/inverse is a ubiquitously adopted convention based on their relative abundances. |
Blanket | mass of elements forming distal cover. {Theodoridis 1984} |
Flange | rim structure of helicolith (shield is also used by some workers). |
Origin | location of first/shortest elements of flange on the proximal side. |
Proximal plate | inward radiate elements on proximal side of central-area. |
Spur | spike-like expansion of flange near its termination (e.g. H. recta). |
Termination | location of last elements of flange on the distal side. |
Wing | broad expansion of flange near its termination (e.g. H. carteri). |
Block | zone of holococcolith that behaves in cross-polarized light as one unit. |
Cavity | open central part of holococcolith, not filled by crystallites (e.g. Calyptrosphaera, Zygosphaera). |
Crystallite | individual minute crystal (typically ca. 0.1 microns). |
Crystallite arrangement | pattern of crystallites visible on a surface. Types: hexagonal - crystallites arranged in hexagonal array (with C-axes directed radially) hexagonal meshwork - similar but with regular array of perforations due to omission of single crystals (e.g. Calyptrosphaera oblonga). rhomboid - crystallites arranged in rhombohedral array (c-axes oblique to surface) (e.g. Syracolithus confusus). |
Depression | pit on surface, not opening into a cavity. |
Distal-cover | distal layer(s) of crystallites, covering cavity (may merge into rim or be discrete from it). |
Perforation | opening in wall the size of one crystallite. |
Plug | distally positioned block (e.g. Lucianorhabdus). |
Pore | opening in wall larger than one crystallite (e.g. Gliscolithus). |
Proximal flange | sub-horizontal protrusion from base of rim. |
Proximal-plate | proximal layer(s) of crystallites (nearly) covering base of coccolith. |
Proximal-ring | proximal layer(s) of crystallites confined to edge of coccolith. |
Rim | peripheral zone discrete in cross-polarized light from the main blocks (typically rim elements have radial c-axes). |
Septum | layer(s) of crystallites forming internal wall. |
Wall | layer(s) of crystallites forming sub-vertical structure. |
Cavate | with large cavity inside rim (e.g. Calyptrosphaera). |
Septate | space inside rim is subdivided by septa (e.g. Syracolithus quadriperforatus, Anfractus harrisonii). |
Solid | coccolith consists essentially of a single mass of crystallites without distinct cavity, or septa, with or without depressions, perforations, or pores (e.g. Syracolithus catilliferus) and possibly many fossil holococcoliths. |
Calicalith | open cavate, without distal cover (e.g. Calicasphaera). {Kleijne 1991} |
Calyptrolith | domal cavate, with nearly continuous distal-cover (e.g. Calyptrosphaera). {Lohmann 1902} |
Crystallolith | disc-like solid holococcolith formed of one or two layers of crystallites, with low rim (e.g. Coccolithus pelagicus holococcoliths). {Braarud et al. 1955a} |
Flosculolith | cavate with distal opening partially closed by a vaulted distal-cover (e.g. Flosculosphaera). {Kleijne et al. 1991} |
Fragariolith | proximal plate directly surmounted by blade-like process. (e.g. Anthosphaera fragaria). {Kleijne 1991} |
Gliscolith | cavate with bulbous distal part (e.g. Gliscolithus). {Norris 1985} |
Helladolith | similar to zygolith but with bridge expanded distally into double-layered leaf-like process (e.g. Helladosphaera). {Heimdal and Gaarder 1980} |
Laminolith | solid holococcolith formed of several (>2) horizontal layers of crystallites, with or without perforations/pores (e.g. Syracolithus catilliferus). {Heimdal and Gaarder 1980} |
Zygolith | with bridge-shaped distal-cover (e.g. Corisphaera). {Kamptner 1937} |
Association | a group of systematically arranged individuals. {van Niel, 1994} |
Rosette | association of nannoconids lying side-by-side with their longitudinal-axes radiating from a central point. N.B. It is possible that all rosettes are spherical, but the term sphere is not recommended since this has not been demonstrated, and since nannoconid associations may not be strictly comparable to coccospheres. {Noel 1958} |
Twin | two nannoconid individuals joined at their ends, with ridges and grooves extending across the contact surface. {van Niel 1995} |
Longitudinal axis | axis of rotational symmetry of nannoconid. |
Transverse plane | plane perpendicular to the longitudinal axis. |
Horizontal | directions within the transverse plane. |
Vertical | directions parallel to the longitudinal axis. |
Pole | end of nannoconid, point of emergence of symmetry axis:
apex pole in N. steinmannii at narrower end of specimen {Bronnimann 1955}; base - pole opposite to apex (broader end in N. steinmannii).{Bronnimann 1955} |
Longitudinal view | view of nannoconid parallel to longitudinal axis. |
Plan view | view of nannoconid perpendicular to longitudinal axis. |
Central opening | opening running longitudinally through the nannoconid. Types: canal - narrow, <1 µm; cavity - wide, >1 µm; aperture - expression of the central opening at the ends of the specimen. {Kamptner 1931} |
Bulb | a distinct swelling of the outline (e.g. N. borealis - single, N. paskentiensis - double, N. multicadus - triple). {Trejo 1960} |
Constriction | external indentation of the wall, between bulbs. {Deflandre and Deflandre-Rigaud 1962} |
Flange | horizontal projection around the end of nannoconid. N.B. Flanges may be symmetrical or asymmetrical in end view, and may be present at one or both ends of the specimen. {Stradner and Grün 1973} |
Wall | structure enclosing the central opening. {Kamptner 1931} |
Plate | basic structural element of nannoconid, single sub-triangular platy crystal. (Alternative term wedge, see appendix). {Stradner and Grun 1973} |
Type A-cycle | cycle of plates inclined at a lower angle (angle α) to the horizontal. These are birefringent in longitudinal view (Perch-Nielsen 1988). {van Niel 1992} |
Type B-cycle | cycle of plates inclined at a higher angle (angle β) to the horizontal. These cycles are non-birefringent in longitudinal view and form the dark spiral lines observed in cross-polars in longitudinal view (Kamptner 1931, Deflandre and Deflandre-Rigaud 1962, Perch-Nielsen 1988). {van Niel 1992} |
Angle Δ | angle of the A cycle/B cycle contact to the horizontal. N.B. This is the only angle measurable by light microscopy. {van Niel 1992} |
Cycle spacing | repeat distance between cycles perpendicular to angle Δ, i.e. combined thickness of A and B cycles. |
Diaphragm | plate-like central cycle of elements |
Wall | outer part of nannolith, typically formed of two superposed cycles of elements. |
Reduced cycle | smaller of the two wall cycles. |
Expanded cycle | larger of the two wall cycles. |
Ray, petalloid, block | typical shapes of wall elements (cf. section 4.1.2). |
Apical cycle | upper part of sphenolith, formed of most steeply inclined cycle of elements. Types: Monocrystalline formed of one crystal-unit; e.g. S. heteromorphosus, S. belemnos. Duocrystalline formed of two crystal-units; e.g. S. distentus, S. furcatulithoides. Compound formed of several crystal-units; e.g. S. radians, S. abies. |
Apical spine | elongate extension of apical cycle. |
Base | all of sphenolith except the apical spine. |
Blade | one of three sub-parts of an element, only seen in well preserved material. |
Core | centre of radiation of elements. |
Element | basic component of sphenoliths, each element appears to be a single crystal-unit. |
Lateral cycles | cycles between apical and proximal cycles, not always present. |
Proximal cycle | lowermost cycle of elements. |
Upper/lower part | part above/below the core. |
Attachment surface | contact-surface between two elements. Superfluous synonym, contact-surface seems more objective. |
Bar / Bridge (sensu Theodoridis 1984) | synonyms of disjunct and conjunct bar, especially for helicoliths. We consider these terms confusing. Also they are of limited application, whereas the terms disjunct and conjunct can be applied to any central-area structure, not just bars. |
Bar / Bridge (sensu Aubry 1988) | as per Theodoridis (1984) but with opposite meanings. |
Coccocylinder | cylindrical coccosphere. Superfluous term (despite being based on a very beautiful specimen), numerous coccospheres are aspherical and there is no utility in coining numerous shape related terms. {Covington 1985} |
Column | often used as a synonym of spine, which we prefer. |
Cone | alternative to apical cycle, for fasciculiths. This cycle only forms a conical structure in a few species so we prefer the more neutral term apical cycle. |
Complete/incomplete caneoliths | endothecal coccoliths of Syracosphaera with, respectively, 3 and 2 flanges. The distinction is useful but there is no real need for these rather obscure special terms. Also, we prefer to use the terms complete and incomplete to describe degree of completion of growth of coccoliths.{Halldal and Markali 1955} |
Cribrate central-area | obscure alternative to net. |
Discolith | this term has been widely used for coccoliths with elevated rims but no shields, i.e. muroliths as defined here. We prefer murolith since Discolith has also been used with the different sense of 'a coccolith belonging to the Pontosphaeraceae'. In addition the word discolith is potentially misleading. |
Geometric | unsuitable alternative of polygonal. Ellipses and circles are just as geometric as triangles or pentagons are. |
Heliolith / Ortholith | These terms for coccolith types were originally defined on the basis of the crystallographic orientation of the main elements: Ortholiths - dominant elements large with vertical or tangential c-axis orientation (e.g. Discoaster, Braarudosphaera); Helioliths - dominant elements have approximately radial c-axes giving a "sphérolithique" appearance (e.g. Watznaueria, Reticulofenestra). This concept is of limited use since most heterococcoliths are composed of both vertical and radial crystal-units, whilst for many nannoliths the concept of radial and vertical are unclear. As a result there has been only limited agreement between authors who have used these terms as to which taxa should be included in which group - compare Deflandre (1952), Tappan (1980), Aubry (1984 et seq.). {Deflandre 1950} |
Jugum | synonym of bar. Obscure and superfluous. |
Knob | synonym of boss, especially for discoasters. We prefer boss, and it has more general application. |
Labiatiform | elongate double-lipped sacculiform protrusion. Unnecessarily specialised term, applying to only one taxon Algirosphaera robusta.{Halldal and Markali 1955} |
Limb / spoke | synonym of arm. We prefer arm and it has been more widely applied. |
Loxolith rim | synonym of zeugoid rim, which we prefer. |
Marginal area | rim. We prefer rim since it is handier for forming complex terms (e.g. proximal rim element), and because marginal area suggests an unimportant feature whereas this is the most important part of many coccoliths. {many authors} |
Nanofossil, Nanoplankton | synonyms of nannofossil and nannoplankton. Both nano- and nanno- are etymologically valid prefixes derived from the Greek word nanos (dwarf). We prefer nanno- on the following grounds. A. General usage, as noted by the Oxford English Dictionary (2nd edn 1989), nearly all palaeontologists use nannofossil and many biologists use nannoplankton so this is the de facto "correct" spelling. B. Priority, this was the spelling adopted by Lohmann (1909), when he coined the term nannoplankton. C. Differentiation, the SI use of nano- implies 10-9 (e.g. nanometre). |
Optically continuous/ discontinuous structure | essentially synonyms of conjunct and disjunct. We prefer the latter as they are shorter and less potentially misleading. |
Oval, ovoid | often used as synonyms of elliptical, but these terms more accurately mean egg-shaped and so are very rarely applicable to coccoliths. |
Pterygal, meta-pterygal, pre-pterygal, anti-pterygal | orientation terms for helicoliths. Elegant but too obscure for practical use. {Theodoridis 1984} |
Precession | alternative to obliquity for description of element orientation in plan view. The common scientific use of precession is related to orbital motions which are not analogous to the element orientation. Hence the special use of this term for coccoliths is obscure. {Black 1972} |
Prymnesiophyte | alternative to Haptophyte. Green and Jordan (1994) showed that Haptophyta, rather than Prymnesiophyta is the correct division level name, it follows that haptophyte is preferable to prymnesiophyte as the informal name for members of the division. |
Rhombolith | synonym of scapholith. Both are often used, we follow Braarud et al. (1955a, 1955b) in using scapholith. {Halldal 1954} |
Stomatal opening, stomatal coccolith | circum-flagellar coccoliths. Stomata implies mouth, and so has unwanted functional implications. {Halldal and Markali 1955} |
Wedge | element of a nannoconid. Bronnimann also used the term plate and this is preferred since it better describes the shape of nannoconid elements as shown by electron microscopy. {Bronnimann 1955} |
Zygodiscid rim | synonym of zeugoid rim, which we prefer. |
Coccolith | plate-like calcareous component of haptophyte cell-covering, homologous with organic scale. {Huxley 1858} |
Heterococcolith | coccolith formed of crystal-units of complex shape. {Braarud et al. 1955a, 1955b} |
Holococcolith | coccolith formed of numerous minute (<0.1 µm) crystallites all of similar shape and size. {Braarud et al. 1955a, 1955b} |
Murolith | any heterococcolith with elevated rim but without well-developed shields. {Young 1992a} |
Nannolith | calcareous structure lacking the typical features of hetero- or holococcoliths and so of uncertain affinity. {?Perch-Nielsen 1985} |
Placolith | any heterococcolith with two or more well-developed shields. {Lohmann 1902} |
Planolith | any planar heterococcolith, rim not elevated. {Young 1992a} |
Calicalith | tube-shaped holococcolith, flaring, open distally. {Kleijne 1991} |
Calyptrolith | cap-shaped holococcolith. {Lohmann 1902} |
Crystallolith | planar holococcolith, rim weak. {Braarud et al. 1955a, 1955b} |
Flosculolith | flaring, tube-shaped holococcolith, with distal opening partially closed by a vaulted roof. {Kleijne et al. 1991} |
Fragariolith | holococcolith with simple basal ring and leaf like process. {Kleijne et al. 1991} |
Gliscolith | tube shaped holococcolith with bulbous distal part. {Norris 1985} |
Helladolith | tube-shaped holococcolith with bridge developed into leaf-like process. {Heimdal and Gaarder 1980} |
Laminolith | laminated disc-shaped holococcolith +/-pores. {Heimdal and Gaarder 1980} |
Zygolith | tube-shaped holococcolith with bridge. {Kamptner 1937} |
Ceratolith | horseshoe shaped nannolith of Ceratolithaceae. |
Discoaster | stellate nannolith of Discoasteraceae. |
Fasciculith | compact, top-shaped nannolith of Fasciculithaceae. |
Helicolith | coccolith with helical flange of Helicosphaeraceae. |
Heliolith | stellate nannolith with birefringent central-area , of Heliolithus (Palaeogene). |
Lepidolith | simple planolith, formed of two elements, of Gladiolithus. {Halldal and Markali 1955} |
Lopadolith | elevated murolith of Scyphosphaera. {Lohmann 1902} |
Osteolith | femur-shaped circum-flagellar coccolith of Ophiaster and Michaelsarsia. {Halldal and Markali 1955} |
Pentalith | stellate nannolith with 5 segments of Braarudosphaeraceae. {Gran and Braarud 1935} |
Protolith | murolith with non-imbricate rim of Stephanolithaceae, Parhabdolithaceae. {Bown 1987} |
Rhabdolith | planolith (+/- spine) of Rhabdosphaeraceae (also has been for spine bearing coccoliths in general). {Schmidt 1870} |
Scapholith | rhombic murolith of Calciosoleniaceae. {Deflandre and Fert 1954} |
Sphenolith | nannolith of Sphenolithaceae. {Deflandre 1952} |
[Areolith] | cap-shaped holococcolith with interior ridges and areolae. {Norris 1985} |
[Asterolith] | obsolete term for stellate nannoliths. {Sujkowski 1931} |
[Caneolith*] | endothecal murolith (+/- flanges) of Syracosphaeraceae. {Braarud et al. 1955a, 1955b}. |
[Cribrilith] | perforate murolith of Pontosphaeraceae; in effect a synonym of discolith and so superfluous. {Halldal and Markali 1955} |
[Cricolith*] | narrow-rimmed placolith of Pleurochrysidaceae. {Braarud et al. 1955a, 1955b} |
[Cyatholith] | obsolete, alternative to placolith. {Kamptner 1948} |
[Cyclolith] | obsolete, circular placolith. {Kamptner 1948} |
[Cyrtolith*] | exothecal planolith or inverted murolith of Syracosphaeraceae. {Braarud et al. 1955a, 1955b} |
[Discolith*] | murolith of Pontosphaeraceae (has also been used for muroliths in general). {Huxley 1868} |
[Heliolith] | heterococcolith with c-axes of main elements radial. {Deflandre 1950, Aubry 1984 et seq.} |
[Ortholith] | nannolith or holococcolith with c-axes of main elements tangential or parallel{Deflandre 1950; Aubry 1984 et seq.} |
[Pappolith*] | murolith of Papposphaeraceae. {Norris 1983} |
[Pentagolith] | Pentagonal coccolith with >5 elements, e.g. Goniolithus. These are so rare that the term is redundant. {Farinacci et al. 1971} |
[Porolith] | obsolete term for perforate element of Thoracosphaera. {Deflandre 1952} |
[Prismatolith] | obsolete term for imperforate element of Thoracosphaera. |
[Rhombolith] | alternative term for scapholith. {Halldal 1954} |
[Tremalith*] | vase-shaped murolith of Hymenomonadaceae. {Lohmann 1913} |