GLOSSARY OF SCIENTIFIC TERMS
FOR KILLI-HOBBYISTS

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Notes:

This glossary is a copy of the printed pages in Killi-Data 2000. It has been updated and extended in Killi-Data 2007 : to obtain it click on ORDER.

"°" means that the word is defined elsewhere in the glossary.
"§" means that this term is exemplified in the drawings (of the book, only).


A.§ Anal ray° counts.

Acid water. Water with a pH below 7.0. A fairly frequent occurrence in pure rainwater biotope°, and especially black° waters.

Alkaline water. Water with a pH above 7.0. Such water is just the reverse of being acid; usually water containing dissolved lime, but also brackish° or marine or hypersaline° waters.

Allometry. Differential size or growth in 2 or more measurements (e.g., between juvenile and adult stage).

Allopatric populations. Populations° living in separate biotopes° or biogeographical areas (Allopatry).

Allotype. One of the types° (or not), different by its sex° from the holotype°: usually the female (usage not advised by I.C.Z.N.°).

Anal fin°. Anal Length (A.L.§), from base° to tip°, is measured (in mm or as a % of S.L.°), possibly in view of showing sexual dimorphism°. Also measured: Anal Base (A.B.§): length between the first and the last ray.

Anal Area or Zone. Part of sides°, situated above the Anal fin°.

Annual species. A species of which the freeswimming individuals live for less than one year, the fertile eggs hibernating in the soil during desiccation°.

Anaerobic. In the absence of oxygen. Black° waters are very poor in dissolved oxygen.

Arm. Branch of a chromosome°, fastened to a knot named the centromere (A.§).

Apomorphic. In cladistics°, defines a derived (i.e. not primitive) character (opposite: plesiomorphic°).

Base of fins. Distance between the first and the last ray° of the fin°, measured near the body for Anal, Dorsal and Pectoral fins.

Biospecies. A zoological species defined by its reproductive isolation from other biospecies (synonym: the biological species).

Biotope. Place where the fish live and its environment.

Black waters. Usually from forest streams with much humic content; high acidity (low pH) and low conductivity.

Brackish water. Water containing a mixture of fresh and salt waters, such as in estuaries.

Branchiostegal rays. Ossified rays, that sustain the lower membrane of the branchial cavity.

Caudal fin° C§. Rarely are Caudal rays counted, branched or unbranched.

Caudal length. Easily computed by T.L.° minus S.L.°, in mm or as a % of S.L.

Caryotype. See Karyotype°.

Chromosome. In the nucleus, a body carrying the genetic material: made of a centromere and 1 or 2 arms°.

CIR. Circumpeduncular scales. Count around the narrowest part of Caudal peduncle, in a zig-zag row.

Clade. Group of taxa sharing exclusively a common ancestor.

Cladistics. Method of taxonomy° (or systematics°) which groups strictly monophyletic° taxa° based on apomorphic° characters, only.

Cladogram. Diagrammatic tree showing monophyletic° taxa°, up to their common ancestor.

Clearing and staining. Technique which involves the clearing of muscle tissues and staining of bones; it allows the study of the osteology° (cleared and stained specimen).

Complex. Group of monophyletic° species; a concept similar to superspecies°.

Conductivity of water. An electrical measurement that shows the amount of mineral matter dissolved in water or the salinity of the water. High figures equal much mineral matter. Unit: microSiemens (µS).

Conspecific populations. Populations belonging to one and the same species.

Cryptic (or Kryptic) species°. Allopatric° isomorphic° (bio)species, only distinguished by genetic isolation and color pattern° or other minor external features, from other members of a superspecies°.

Ctenoidy. Usually spine-like structures developing on the edges of scales or at the ends of fin ray segments (rarely, in the middle). Ctenoid spines are more often encountered in old dominant males.

Cytology. The study of cells.

D.§ Dorsal ray° counts.

D/A § (Dorsal over Anal). This count shows the relative posterior (resp. anterior) position of Dorsal insertion to Anal by counting the number of rays of Anal, up to vertical of the Dorsal origin: e.g., +3 means that the first Dorsal ray is inserted above the third Anal ray; -3 means that the first Dorsal ray is inserted ahead of the first Anal ray and that the third Dorsal ray is above the first Anal ray. It is always interesting for evolution analysis and assignments to superspecies.

Description (original). First published definition or diagnose of a new taxon° (subsequently: redescription).

Desiccation. Period during which certain biotopes° are dried up: the dry season.

D.H. German hardness (degrees). 1 DH = 17.86 ppm (US).

Diagnosis. Key elements to define and differentiate a taxon°.

Diapause. Temporary arrest of the egg development. Up to 3 diapauses have been reported to occur in annual° species.

Dimorphism. Difference in morphology°: may be in terms of sex°, i.e. between male and female, or of age, i.e. between juvenile and adult.

Diploid. The normal (somatic) cell containing a diploid (paired) set of homologous chromosomes° from mother and father.

Dorsal Area or Zone. Part of sides°, situated below the Dorsal fin°.

Dorsal fin°. Length (D.L.), from base° to tip°, is measured (in mm or as a % of S.L.), possibly in view of showing sexual dimorphism°. Also measured: Dorsal Base (D.B.§): length between the first and the last ray.

Ecological conditions. All external factors influencing the life of the population° in a certain place. Usually climatic conditions, soil type, water type, forest, savannah, altitude, etc.

Electrophoresis. Identification technique based on distinction of protein movements.

Embryology. Study of the egg (membrane, development, diapauses°); in Cyprinodonts, egg needs a long development time and has a thickened chorion to resist to desiccation°.

Endemic. Restricted to a usually rather small geographical area.

Endangered species. A species that runs the risk of extinction° if appropriate protective measures are not instituted; thus, included in Appendix II of the Convention of Washington on the International Trade in Endangered Species of Wild Fauna and Flora (C.I.T.E.S.).

Extinct species. A species thought to have definitely disappeared throughout its geographical range due to competition or biotope destruction.

Eye Diameter §. Distance between anterior and posterior orbital walls (in mm or as a % of S.L.).

F-generation. Characterizes the number of generations obtained by breeding or crossing: F0 means wild strain, F1 first generation from wild parents or obtained in crossings. Then F2, F3… Fertile F3 generation is necessary to confirm interfertility.

ff-scales §. A series of frontal scales that usually bridges the grooves for the lateral line organs of the front°, dividing these grooves into supra-orbital and post-orbital parts.

Falaise. The steep slope which separates the inland plateau (highlands°, above 350 meters high) from the coastal lowlands°.

Fins. Organs of motion and equilibrium; distinguished in unpaired (Caudal or tail, Dorsal and Anal) or paired (Pectorals, Ventrals or Pelvics). In Cyprinodonts, there is neither Adipose fin (behind the Dorsal) nor double Dorsal fins.

Fission §. The decomposition of a two-armed chromosome° by acentromeric break.

Front. Superior part of head, in between the eyes; a very important part for the Cyprinodonts (sensory organs), since most species are near-to-surface dwellers.

Frontal scalation §. Specific arrangement of the scales on the front°; depending on the scales overlying the others, the arrangement is named "dd, ee, ff, g" or "h"; the "a" scale covers the pineal organ.

Frontal neuromasts°. The neuromasts situated on the front in grooves or pores. Their taxonomic significance is important at or above the genus level.

Frontier species. A biospecies° with a restricted geographical distribution, living at the border of the range of its superspecies° and thus facing the competitive pressure of the neighboring superspecies.

Fusion §. An exchange of arms between two subtelocentric° chromosomes°. See also Robertsonian° fusion.

Genotype. The sum of the genetic characters of the individual.

Gill Rakers. Sort of spines in variable numbers, on the edges of the branchial arches; those on the first arch (ceratobranchial and epibranchial) are counted for systematic° purpose.

H-scale §. Scale, usually rather small, situated in front of the central g-scale and often below that scale.

Haploid. Cells having only one set of chromosomes°. Sex° cells are haploid, normal cells are diploid°.

Hd.§ (Head). Distance from the tip° of the mouth to the back of the fleshy opercle (in mm or as a % of S.L.).

Height §. Body depth at Anal level, distance between upper and lower part of the body (in mm or as a % of S.L.°). The greatest height, usually at the vent, may be also measured, but it is distorted in pregnant females and overfed aquarium specimens. Height, at Caudal peduncle (dcp§), is also measured. Body height is an uncertain criterion, as there may be allometry° in growth: juveniles are more slender.

Hemoglobin. The compound that transports the oxygen via the blood stream to different parts of the body and produces the red color of the blood. The so-called hemoglobin pattern gives indication of phylogeny°.

Heteromorphic. With a difference in morphology°. Two superspecies are heteromorphic, as well as two morphospecies (opposite: isomorphic).

Highlands. Regions of mountains or inland plateau (above 350 m altitude), separated from lowlands° by a falaise°; if steep, then the fauna is distinctive from that of lowlands°.

Holotype. A single preserved (fish) specimen for which a certain zoological name has been attached.

Homoplasy. Parallely acquired character (cladistics°), either by convergence or by reversal to a previous primitive state.

Hybrid. An individual produced by the crossing of individuals from different populations, usually from different biospecies° or morphospecies°.

Hypersaline. Water with higher salt concentration than sea, as in salt marshes (> 35 parts per thousand).

I.C.Z.N. International Commission of Zoological Nomenclature. A commission which enacts the rule of nomenclature° (the Code) and exceptionally settle, on request, debated cases.

Inversion. § A chromosomal structural change between one extremity and the centromere fastening.

I.O. (Interorbital Space). Distance between the eyes or width at eye level (in mm or as a % of S.L.°).

Isomorphic. With the same morphology° or a proportionate equivalent. Components of a superspecies° are isomorphic and then named cryptic° species, when isomorphic° (opposite: heteromorphic).

Karyotype (or better linguistically: caryotype). A schematic figuration of the haploid chromosome° complement.

Killi (plural: Killies). Old Dutch name (Kill: creek), first used for some Fundulus species from North America, then by extension for all oviparous° Cyprinodonts.

Lateral line. Sensory organs on mid sides of the fish. Rare in Cyprinodonts.

L.L. Scale Count on Lateral Line or Series. From the gill opening to the rear end of hypural plate; if counted, those inserted posteriorly on Caudal are separated by a "+".

Lowlands. Low altitude regions, mostly near the coast. Its fauna is often distinctive from that of highlands°.

Lumpers. Persons who are global and synthetic minded ; they tend to describe fewer taxa (opposite: splitters°).

Meiosis. The type of cell division during which reproductive cells are produced.

Meristics. Morphological characters that can be counted (fin rays°, scales°, vertebrae°, gill arches°, branchiostegal rays°, etc.).

Metacentric §. A two-armed° chromosome° in which the centromere is situated midway along the axis.

Mitosis. The normal cell division.

Monophyletic. Which belongs to a single common ancestor (opposite: polyphyletic°).

Monotypic. With a single unit; for example, a monotypic genus encompasses only one species.

Morphology. Shape of the fish, in general and all details that are counted (meristics°), measured (morphometrics°) and described (scalation°, neuromasts°).

Morphospecies. A zoological species defined by the external morphology, including colors.

Morphometrics. Morphological characters that can be measured in mm, then computed as a % of S.L.° (e.g., P.Do.°, P.A.°, Height°, Hd°, etc.).

N. The number of specimens, characters (… ) studied.

n. The haploid chromosome number (2n is the diploid° number; A, the number of arms°).

Neotype. Subsequently designated type to replace the original description type which is lost or may never have existed in the first place.

Neuromast. A sensory organ of the lateral line° or the head°, open in the form of a button or within a pore.

Nomenclature. The zoological system of naming.

Nominal species. Zoological name at the species level, independent of its validity.

Nominate subspecies (or better: nominotypical subspecies). The first-named subspecies, repeating the species name, e.g., Epiplatys fasciolatus fasciolatus.

Ocellus §. Dark blotch (often supracaudal), surrounded or not by gold: a female character (not always).

Opercle (or Operculum). Gill-cover. Part of skeleton that covers the branchial opening.

Opercular (short for Preopercular) neuromasts. Sensory organs situated in a groove in-between the posterior wall of eye and opercle.

Osteology. The study of the skeleton.

Oversized arms. Chromosome° arms° measuring more than about 6%.

Oviparous. Egg-laying. Characterizes Killies° within the Cyprinodonts (opposite live-bearers or viviparous).

P Pectoral ray° counts (rarely counted).

Paratypes. The types°, other than the holotype°, when the description° is based on several specimens.

Pattern. Color pattern: drawing of colors, especially important for unpaired fins° and posterior sides°.

Pectoral fin. Length of fin from base° to tip° is measured in mm or as a % of S.L., as a characteristic of some species having extensions.

Pericentric inversion §. A chromosomal structural change.

pH. A term that indicates the degree of alkalinity° or acidity° of water. Ex: pH4 (very acid), pH9 (very alkaline).

Phenotype. The sum of visible characters of the individual, and by extension, of a population° or a biospecies°.

Peduncle. Part of the body on which Caudal° fin is attached.

P.A. (Preanal Length) §. Distance from the tip of the mouth to the first Anal ray (in mm or as a % of S.L.°).

P.Do. (Predorsal Length) §. Distance from the tip of the mouth to the first Dorsal ray; this is a major diagnostic feature, since it measures the position of that fin; it is recognized in all fishes as an evolutionary mark (in mm or as a % of S.L.°).

pDor (Predorsal Scales counts) §. Count starts from behind the pineal scale ("a"), up to the scale just in front of Dorsal; this is reasonable since several minute scales nearer the mouth may be wiped out; however, the "a" scale is not always easily located.

Plesiomorphic. In cladistics°, it defines a primitive or ancestral (i.e. not derived) character (opposite: apomorphic°).

Polyphyletic. Which gathers taxa having several ancestors (opposite: monophyletic°).

Population. Inhabitants of a biotope for a given species. By extension, the aquarium strain that is developed from the wild specimens brought back alive.

Post-opercular blotch. Black marking situated immediately behind Pectoral root and operculum°.

Preopercle. A disc-like bone just in front of the opercle° and situated below the eye.

Preorbital. Refers to the space between the eye and the mouth.

P.V. §. (Preventral or prepelvic length). Distance from the tip of the mouth to the first Ventral ray (in mm or as a % of S.L.°).

Radio(photo)graph. X-ray photo that shows the bones; particularly useful to fix morphomeristics with certainty (e.g., for old types°, with damaged or folded fins°), to count vertebrae° and to study the osteology°.

Ray counts at Dorsal (D.) and Anal (A.). Counts include all (even half-) branched and unbranched rays, the last one being counted as 2 if split near to base; the first minute ray can only be seen by experienced researchers or counted on radiophotographs° in many cases.

Relict. The remaining populations° of a morphospecies° that is supposed to have had a much larger geographical distribution in the past.

Robertsonian fusion §. A chromosomal change, which transforms two (sub)telocentric° chromosomes° into a single large metacentric°.

Scalation. Specific organisation of the scales (synonym: squamation); example: frontal scalation.

Sensory organs. The fleshy filaments or buds, groups of sensitive cells with a sensory function; often, they develop around ctenoid (or not) structures.

Sex. Male or female; sexation corresponds to the date when sexes are distinguishable; sexual maturity (later) to the first date of spawning.

Sides. Flanks of the fish with key parts as post opercular°, ventral°, dorsal°, peduncular°, posterior and mid.

Sibling species. Biospecies° that cannot be separated on the basis of their phenotypes. Also called cryptic° species, if allopatric°. Sympatric° biospecies° are extremely rare in Cyprinodonts.

Species. The basis for taxonomy°: see biospecies° and morphospecies°.

Splitters. Persons who are analytic minded; they tend to describe many taxa and to recognize an excess of taxonomic units previously described by others (opposite: lumpers°).

Standard Length (S.L.§). Distance from tip of mouth to rear end of the hypural plate, as ascertained by bending Caudal; this is the basic criterion for morphological proportions or morphometrics° (in %).

Subspecies. The lowest taxonomic° unit in zoology. Subspecies differ by their phenotype°, are interfertile, and are allopatric° (especially vicariant°).

Superspecies. A morphospecies° composed of several biospecies° or cryptic° species.

Subtelocentric §. A chromosome° composed of a long and a short arm° (usually shorter than 2%).

Sympatry. Living in the same geographical spot or biotope°. Rule: components of distinct superspecies° live in sympatry, whereas components of the same superspecies° are allopatric°. Some authors define sympatry as living in the same region or river basin, and therefore use syntopic in the herein restricted sense.

Synapomorphy. Derived character shared by two or more taxa° (cladistics°).

Symplesiomorphy. Primitive character shared by two or more taxa° (cladistics°).

Synonym. Different names for one and the same genus, species, or subspecies. It is said to be junior if described after and senior if described before the discussed name.

Syntypes. Previously, a series of types° was deposited without distinguishing the holotype°, bearing the risk of being composed of several species. To clarify the situation, a lectotype is designated among the syntypes, the remaining specimens being named paralectotypes.

Systematics. Pyramidal classification of organisms, down from the superorder, order (ending: -formes), suborder (-oidei), superfamily (-oidea), family (-idae), subfamily (-inae), tribe (-ini), subtribe (-ina), genus, subgenus, species to the lowest unit, the subspecies°.

Taxonomy. The study of names (Taxon; plural: Taxa). By extension, the classification of organisms, like systematics°.

Telocentric. Chromosome° with only one arm° (synonym: acrocentric).

Tip. Distal extremity of fin, mouth, etc…

T.L. § (Total Length). distance from tip of mouth to end of longest Caudal ray; a key criterion when the fin is not damaged and the specimen is adult. Full aquarium size is given in mm for males: this can be up to 30 % more than in nature, where competition, lack of food and predation limit life expectancy and size.

TRAV.§ (Transverse Series). Count from the first scale° (even halved) in front of Dorsal°, anteriorly downwards to Anal base°.

Triploidy. The normal cells containing not two but three sets of chromosomes (may occur in backcrossings of hybrid females).

Type° locality (also Terra Typica). Place where the holotype was collected.

Types. Specimens declared as such by the describer, which are deposited in Museums and represent the species.

Univalent. When homologous chromosomes° fail to pair during the first meiotic division, they segregate at random. Elements shorter than 2% usually occur as univalents and may become lost. Univalents often occur in hybrids.

V.§ Ventral ray° counts.

Ventral or pelvic fin. Length of fin from base° to tip° is measured in mm or as a % of S.L.°, as a characteristic of some species having extensions.

VER. (Vertebrae). From occipital bone to hypural plate; abdominal vertebrae (Ab) are distinguished by having paired ribs, whereas caudal vertebrae (Cd) have caudal arches. Counts are based mainly on radiophotographs°.

Vicariant. Living in two neighboring areas. Components of a superspecies°, or if interfertile, subspecies° are vicariant.


 

 

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