Signs of life: rediscovery of Erythrolamprus andinus (Dixon, 1983) (Serpentes: Dipsadidae) in Bolivia

The tribe Xenodontini Bonaparte, 1845 (Serpentes: Dipsadidae) contains five genera of snakes: Baliodryas ‍Zaher & Prudente, 2020, Erythrolamprus Boie, 1862, Eutrachelophis Myers & Cadle, 2014, Lygophis Fitzinger, 1843, and Xenodon Boie, 1826 (‍Zaher & Prudente, 2020; ‍Entiauspe-Neto et al., 2021; ‍Uetz et al., 2021). The genus Erythrolamprus is one of the most taxonomically diverse and unstable groups of snakes, with 55 species currently recognised from Central and South America (‍Wallach et al., 2014; ‍Ascenso et al., 2019; ‍Nogueira et al., 2019; ‍Entiauspe-Neto et al., 2021; ‍Uetz et al., 2021).

In Bolivia, the genus Erythrolamprus is represented by 16 species: E. aesculapii (Linnaeus, 1758), E. albertguentheri (Peracca, 1897), E. almadensis (Wagler, 1824), E. andinus (‍Dixon, 1983), E. breviceps (Cope, 1860), E. ceii (Dixon, 1991), E. dorsocorallinus (Esqueda, Natera, La Marca & Ilija-Fistar 2007), E. jaegeri (Günther, 1858), E. macrosomus (Amaral, 1935), E. miliaris (Linnaeus, 1758), E. poecilogyrus (Wied-Neuwied, 1825), E. reginae (Linnaeus, 1758), E. sagittifer (Jan, 1863), E. taeniogaster (Jan, 1863), E. taeniurus (Tschudi, 1845) and E. typhlus (Linnaeus, 1758) (‍Leynaud & Bucher, 1999; ‍Wallach et al., 2014; ‍Ascenso et al., 2019; ‍Nogueira et al., 2019; ‍Reichle, 2019; ‍Uetz et al., 2021). However, very few aspects of the biology and distribution of these species are known (‍Cortez-Fernández, 2009).

Erythrolamprus andinus is only known from two localities: the type locality in Incachaca, Cochabamba, Bolivia (‍Dixon, 1983) and Wayrapata, department of Cusco, Peru (‍Alonso et al., 2001). However, to our knowledge, no description of the external morphological characters of living individuals or images of recorded specimens are known (‍Dixon, 1983, ‍1989; ‍Alonso et al., 2001; ‍Wallach et al., 2014; ‍Aguayo et al., 2016; ‍Uetz et al., 2021). The types described by Dixon (‍1983) were collected by J. Steinbach in 1921. After J. Steinbach’s collection, no other specimens attributable to this species have been recorded in Bolivia.

Fig. 1.— Individual of Erythrolamprus andinus recorded in Incachaca (type locality), Cochabamba, Bolivia: (a) dorsal view of the head and the body; (b) general view. (Photographs AO).

Fig. 1.— Espécimen de Erythrolamprus andinus registrado en Incachaca (localidad tipo), Cochabamba, Bolivia: (a) vista dorsal de la cabeza y del cuerpo; (b) vista general. (Fotografías AO).

One hundred years after the only known Bolivian specimens were collected by Steinbach, during a field trip carried out by the park rangers on May 4^th 2021, a topotype specimen of Erythrolamprus andinus (Fig. 1) was found active during day time, at 11:42 hours, adjacent to a mature secondary montane (Yungas) forest in Incachaca (17°14’10.4” S; 65°48’50.8” W, 2169 m above sea level) (Fig. 2), Carrasco National Park, Cochabamba, Bolivia. The individual registered exhibited characters shown by the specimens in the type series of E. andinus: (1) moderate body length (SVL 300 mm); (2) dorsum of the head olive green; (3) broad black stripe across the eye and the last supralabial; (4) midbody colour pattern consisting of black vertebral and paravertebral lines along the body and tail (pattern “D” of Dixon’s 1983: 131, fig. 6]; (5) combination of 15 dorsal scales; (6) 8 supralabials and 8 infralabials; and (7) 2 preoculars and 2 postoculars. The dorsum was brown, becoming darker from the middle of the body towards the tail, and the vertebral and paravertebral lines were black (Fig. 1).

Due to the rarity of this species, which is considered Endangered in Bolivia (‍Cortez-Fernández, 2009), the specimen was not collected. The photographic record provided herein represents the first picture of a living individual of this species (Fig. 1).

Fig. 2.— Geographical distribution of Erythrolamprus andinus in Bolivia. Red circle: new record at the type locality; green line area: Carrasco National Park.

Fig. 2.— Distribución geográfica de Erythrolamprus andinus en Bolivia. Círculo rojo: nuevo registro en la localidad tipo; área con línea verde: Parque Nacional Carrasco.

Conservation Status. In Bolivia, Erythrolamprus andinus is only known from its type locality and, previous to the new record provided herein, only the type series was known. As a consequence, population data for this species are lacking. It is currently listed as Endangered in the Red Book of Endangered Species of Bolivia (‍Cortez-Fernández, 2009) and as Data Deficient in the IUCN Red List (‍Aguayo et al., 2016). The surroundings of the type locality are largely characterised by severe forest fragmentation due to agriculture and cleared pastures, which continue to expand in the vicinity of the area (O. Quinteros-Muñoz, pers. obs.). We recommend that the conservation status of E. andinus be reclassified from Data Deficient to Critically Endangered, based on criterion B2ab (ii,iii) (‍UICN, 2012).