Mecistops leptorhynchus (BENNETT, 1835)
Can you confirm these amateur observations of Mecistops leptorhynchus?
|Higher Taxa||Crocodylidae (Crocodylia, crocodiles)|
|Common Names||E: Central African slender-snouted crocodile|
F: faux gavial d’Afrique Centrale, faux gavial centrafricain
|Synonym||Crocodilus leptorhynchus BENNETT 1835: 128|
Mecistops leptorhynchus — SHIRLEY et al. 2018
Mecistops cataphractus — PAUWELS et al. 2019
|Distribution||Central African Republic, Republic of the Congo (Brazzaville), Democratic Republic of the Congo (Kinshasa, Zaire), Equatorial Guinea, Gabon, Cameroon|
Type locality: unknown origin (see comment)
|Types||Holotype: BMNH 1922.214.171.124 (NHMUK), juvenile|
|Diagnosis||Diagnosis. When the geographic origin of a specimen in question is unknown, genetic barcoding (Hebert et al. 2003; Hebert & Gregory 2005) can be easily used for species identification. We described a 921 bp fragment of the mitochondrial COI containing 43 sites that segregate the two Mecistops species (Table 2; Shirley et al. 2014). Adult Mecistops leptorhynchus is readily identifiable by the lack of squamosal bosses, which are only rarely present as an ontogenetic development in the largest and oldest specimens; an acute projection formed by the pterygoids between the palatines; a posteriormost point of the premaxilla that is even with or posterior to the third maxillary tooth; and an anteriormost point of the nasal that is posterior of the first maxillary tooth. Mecistops leptorhynchus sub-adults and adults are more lithe and smoother in appearance, partly due to less prominently keeled scales and osteoderms, as well as fewer postoccipital and accessory nuchal scales that are more orderly and less heavily keeled than in M. cataphractus. Mecistops leptorhynchus has 25, usually 26, or more ventral scale rows. Mecistops leptorhynchus is distinguished from M. cataphractus populations that share this trait by the lack of heavy jaw and body spotting and far fewer accessory nuchal and postoccipital scales.|
|Comment||Type locality: The locality, given originally as “apud. Fernando Po”. The notation “apud” is commonly used in the botanical taxonomic literature to signify “near,” “next to,” or “beside,” in this case Fernando Po. In reality, Fernando Po was an incredibly poor choice of geographic descriptor, even with the modifier, as this island has never had a population of Mecistops. More likely, the specimen originated from Gabon or the Republic of Congo; a ship returning to England from Africa was more likely to stop at Bioko Island (Fernando Po) on its way west from Central Africa than detouring east from West Africa (Shirley et al. 2018).|
Distribution: see map in Shirley et al. 2018 (Fig. 1). Reports from Angola, Burundi, or Sudan and many other places remain unconfirmed; the species appears to be extinct in Chad now (Shirley et al. 2018). For a map with localities in Equatorial Guinea see SÁNCHEZ-VIALAS et al. 2022.
|Etymology||Bennett (1835) did not provide an etymology for leptorhynchus. However, ‘lepto’ is derived from the Greek leptós meaning thin, fine, or slender and rhynchos meaning beak or snout. Thus, Mecistops leptorhynchus is a slender snouted crocodylian of the genus Mecistops, which Bennett may have found appropriate given his finding of a longer head length to head width ratio (3:1) than he found in M. cataphractus (2.5:1).|