Chironius

Chironius is a genus of New World colubrid snakes, commonly called sipos (from the Portuguese word cipó for liana), savanes, or sometimes vine snakes. There are 23 described species in this genus.

Species
The following 23 species are recognized as being valid.
 * Chironius bicarinatus (Wied, 1820) – two-headed sipo
 * Chironius brazili Hamdan & Fernandes, 2015
 * Chironius carinatus (Linnaeus, 1758) – Amazon coachwhip
 * Chironius challenger Kok, 2010
 * Chironius diamantina Fernandes & Hamdan, 2014
 * Chironius exoletus (Linnaeus, 1758) – Linnaeus's sipo
 * Chironius flavolineatus (Boettger, 1885) – Boettger's sipo
 * Chironius flavopictus (F. Werner, 1909)
 * Chironius foveatus Bailey, 1955 – South American sipo
 * Chironius fuscus (Linnaeus, 1758) – brown sipo
 * Chironius gouveai Entiauspe-Neto, Lúcio-Lyra, Koch, Marques-Quintela, Diesel-Abegg, & Loebmann, 2020 – Gouvea's sipo
 * Chironius grandisquamis (W. Peters, 1869) – Ecuador sipo
 * Chironius laevicollis (Wied, 1824) – Brazilian sipo
 * Chironius laurenti Dixon, Wiest & Cei, 1993
 * Chironius leucometapus Dixon, Wiest & Cei, 1993 – yellow-headed sipo
 * Chironius maculoventris Dixon, Wiest & Cei, 1993 – central sipo
 * Chironius monticola Roze, 1952 – mountain sipo
 * Chironius multiventris Schmidt & Walker, 1943 – long-tailed machete savane
 * Chironius quadricarinatus (F. Boie, 1827) – central sipo
 * Chironius scurrulus (Wagler, 1824) – Wagler's sipo, smooth machete savane
 * Chironius septentrionalis Dixon, Wiest & Cei, 1993 – South American sipo
 * Chironius spixii (Hallowell, 1845)
 * Chironius vincenti (Boulenger, 1891) – St. Vincent blacksnake

Nota bene: A binomial authority in parentheses indicates that the species was originally described in a genus other than Chironius.

Etymology
The specific names, brazili and spixii, are in honor of Brazilian herpetologist Vital Brazil and German biologist Johann Baptist von Spix, respectively.

Conservation status
The St. Vincent Blacksnake, Chironius vincenti is listed as critically endangered by the IUCN Red List due to its extremely limited range on the Island of St. Vincent.