Central African Slender-snouted Crocodile
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The Central African slender-snouted crocodile (''Mecistops leptorhynchus'') is one of two
species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...
of
crocodile Crocodiles (family (biology), family Crocodylidae) or true crocodiles are large, semiaquatic reptiles that live throughout the tropics in Africa, Asia, the Americas and Australia. The term "crocodile" is sometimes used more loosely to include ...
s in the
genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...
''
Mecistops ''Mecistops'' is a genus of crocodiles, the slender-snouted crocodiles, native to sub-Saharan Africa. Taxonomy and etymology Traditionally placed in '' Crocodylus'', recent studies in DNA and morphology have shown that it is in fact basal to '' ...
''. It was once thought to be a
population Population is a set of humans or other organisms in a given region or area. Governments conduct a census to quantify the resident population size within a given jurisdiction. The term is also applied to non-human animals, microorganisms, and pl ...
of the West African slender-snouted crocodile (''Mecistops cataphractus'') but was elevated to a species after two detailed studies, one in 2014 and the other in 2018. The species was described in 1835 on the basis of a specimen that had died at the
London Zoo London Zoo, previously known as ZSL London Zoo or London Zoological Gardens and sometimes called Regent's Park Zoo, is the world's oldest scientific zoo. It was opened in London on 27 April 1828 and was originally intended to be used as a colle ...
and had been claimed to have been collected in the Fernando Po. Studies of specimens and their molecular sequences established that there were two different species which occurred in distinct hydrological zones. ''M. leptorhynchus'' is easily differentiated morphologically from ''M. cataphractus'' by the absence of a round tubercle or boss on the squamosal scale at the back of the head in the former and present in the latter.


Etymology

The generic name ''Mecistops'' is most probably derived from the
Ancient Greek Ancient Greek (, ; ) includes the forms of the Greek language used in ancient Greece and the classical antiquity, ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Greek ...
words μήκιστ (''mēkist'') meaning "longest" and ὄψις (ópsis) meaning "aspect" or "appearance". The
specific name Specific name may refer to: * in Database management systems, a system-assigned name that is unique within a particular database In taxonomy, either of these two meanings, each with its own set of rules: * Specific name (botany), the two-part (bino ...
''leptorhynchus'' is derived from the Ancient Greek words λεπτός (''leptós'') meaning "slender" and ῥύγχος (''rhýnchos'') meaning "snout". Bennett (1835) may have named the species so because he found it had a longer head width:head length ratio than ''M. cataphractus'', 3:1 versus 2.5:1. Although an analysis of 93 skulls, mainly belonging to mature individuals, by Shirley et al. (2018) found a head width:head length ratio of 2.25:1 for ''M. cataphractus'' and 2.37:1 for ''M. leptorhynchus''.


Taxonomy

Gray Grey (more frequent in British English) or gray (more frequent in American English) is an intermediate color between black and white. It is a neutral or achromatic color, meaning that it has no chroma. It is the color of a cloud-covered s ...
(1844) listed ''Mecistops leptorhynchus'' as a
synonym A synonym is a word, morpheme, or phrase that means precisely or nearly the same as another word, morpheme, or phrase in a given language. For example, in the English language, the words ''begin'', ''start'', ''commence'', and ''initiate'' are a ...
of ''M. bennettii'' even though the former has temporal priority. ''M. bennettii'' was subsumed as a junior synonym of ''M. leptorhynchus'' in Gray's Synopsis of the Species of Recent Crocodilians as he found that the
type specimen In biology, a type is a particular wikt:en:specimen, specimen (or in some cases a group of specimens) of an organism to which the scientific name of that organism is formally associated. In other words, a type is an example that serves to ancho ...
of ''M. bennettii'' ( NHMUK 1977.444) is actually an adult ''M. leptorhynchus''. The
International Code of Zoological Nomenclature The International Code of Zoological Nomenclature (ICZN) is a widely accepted Convention (norm), convention in zoology that rules the formal scientific name, scientific naming of organisms treated as animals. It is also informally known as the I ...
(ICZN) does not allow the
specific epithet In Taxonomy (biology), taxonomy, binomial nomenclature ("two-term naming system"), also called binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, both of which use Latin gramm ...
(species name) to be changed upon removal to a new genus unless it already exists in the new genus. Since ''Mecistops'' was a new genus at the time of its description, ''M. bennettii'' is a
nomen novum In biological nomenclature, a ''nomen novum'' (Latin for "new name"), replacement name (or new replacement name, new substitute name, substitute name) is a replacement scientific name that is created when technical, nomenclatural reasons have mad ...
(replacement name). Shirley et al. (2018) found that the type specimen of ''M. bennettii'' is morphologically and geographically readily assignable to ''M. cataphractus'' so they synonymized ''M. bennettii'' with ''M. cataphractus''. Shirley et al. (2018) also designated ''M. cataphractus'' as the type species of ''Mecistops'' in accordance with Articles 69 and 70 of the ICZN. Article 67.9 of the ICZN states "If a validly fixed
type species In International_Code_of_Zoological_Nomenclature, zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the spe ...
is later found to have been misidentified, the provisions of Article 70.3 apply." Article 70.3 in turn states "If an author discovers that a type species was misidentified, the author may select, and thereby fix as type species, the species that will, in his or her judgment, best serve stability and universality, either." ''M. cataphractus'' best serves stability because it is the most well-studied species of ''Mecistops'' with the most readily recognizable and assignable type material. It also has the widest use in the scientific literature.


Distribution

Central African slender-snouted crocodile occurs widely in
Central Africa Central Africa (French language, French: ''Afrique centrale''; Spanish language, Spanish: ''África central''; Portuguese language, Portuguese: ''África Central'') is a subregion of the African continent comprising various countries accordin ...
(Cameroon, Equatorial Guinea, Gabon, northern Angola, Central African Republic, Republic of the Congo, Democratic Republic of the Congo) and extends into South Sudan in
East Africa East Africa, also known as Eastern Africa or the East of Africa, is a region at the eastern edge of the Africa, African continent, distinguished by its unique geographical, historical, and cultural landscape. Defined in varying scopes, the regi ...
.


References

{{Taxonbar, from=Q57783121 Crocodylidae Crocodilians of Africa Reptiles of Angola Reptiles of Cameroon Reptiles of the Central African Republic Reptiles of the Democratic Republic of the Congo Reptiles of Equatorial Guinea Reptiles of Gabon Reptiles of the Republic of the Congo Reptiles of South Sudan Reptiles described in 1835 Taxa named by Edward Turner Bennett