True cobras wear a Sanskrit generic name
Naja holds the venomous elapids called true cobras across Africa and Asia. King cobras and rinkhals share the nickname but sit outside the genus. Sanskrit naga, meaning snake, supplies the Latinised label—though linking it to English snake is an etymology Manfred Mayrhofer calls not credible.
Species counts wobbled between about twenty and twenty-two until revisions shuffled names; a 2009 treatment folded Boulengerina and Paranaja into Naja and remains widely followed. Bodies are mostly slender; many can reach about 1.84 metres total length, while giants such as the forest cobra approach roughly 3.1 metres.
Geography spans Africa through Southwest, South, and Southeast Asia—the classic cobra belt of hood displays and neurotoxic fame. True cobra is the taxonomist’s way of pruning popular names.
Under the 2009 revision the genus holds 38 species. Every one can deliver a bite fatal to a human. Most venoms are strongly neurotoxic, paralysing the nervous system, but many also carry cytotoxins that cause swelling and tissue death, and some act as anticoagulants or attack the heart. Spitting cobras have fangs with a short, rounded opening on the front face that sprays venom forward, and a study found that all three spitting lineages independently raised levels of phospholipase A2, which amplifies the pain from their cytotoxins.
The Caspian cobra of Central Asia, Naja oxiana, is the most venomous member; a 2019 study put its intravenous LD50 in mice at 0.14 milligrams per kilogram. Water cobras such as Naja christyi come close, at 0.120 milligrams per kilogram in another test. Cobras cause many bites and deaths from Africa, including parts of the Sahara where Naja haje lives, across to East and Southeast Asia. New species keep being split off, among them Naja senegalensis in 2009, Naja peroescobari from São Tomé in 2017, and Naja guineensis and Naja savannula in 2018.
Source: Naja
