Bothriechis torvus (Posada Arango, 1889a)

Arteaga, Alejandro, Pyron, R. Alexander, Batista, Abel, Vieira, Jose, Meneses Pelayo, Elson, Smith, Eric N., Barrio Amoros, Cesar L., Koch, Claudia, Agne, Stefanie, Valencia, Jorge H., Bustamante, Lucas & Harris, Kyle J., 2024, Systematic revision of the Eyelash Palm-Pitviper Bothriechis schlegelii (Serpentes, Viperidae), with the description of five new species and revalidation of three, Evolutionary Systematics 8 (1), pp. 15-64 : 15

Bothriechis torvus (Posada Arango, 1889a)

Figs 15 , 16

Thanatophis torvus Posada Arango, 1889a: 48. Type(s): not designated. Type locality: "lugares cálidos de Antioquia."

Thanatophis torvus Posada Arango, 1889b: 345. Type(s): not designated. Type locality: "regions chaudes d’Antioquia.”

Teleuraspis birri Posada Arango, 1909: 231.

Referred specimens.

All labeled Bothriechis torvus in Suppl. material 1.

Proposed standard English name.

Birri Eyelash--Pitviper.

Spanish names.

Víbora birrí, serpiente guinda, pestañona.

Diagnosis.

Bothriechis torvus is diagnosed based on the following combination of characters: (1) 3 raised supraciliary scales, triangular, but rounded and not spinelike; (2) anterior dorsal head scales keeled; (3) gular scales much smaller than chinshields; (4) 6-18 interoculolabials; (5) 3-8 canthals, most of them with raised triangular projections; (6) loreal in contact with preocular in some populations; (7) yellow morph absent; (8) dorsal bands pink or red; (9) no opposing kidney shaped dorsal marks; (10) black speckles on dorsal scales absent; (11) black speckling on ventral surfaces absent or faint; (12) ventral surfaces entirely white in some individuals; (13) iris pale bluish-green or straw yellow with fine black speckling; (14) 21-23 dorsal scale rows at mid-body; (15) 148-159 ventrals in males, 141-153 in females; (16) maximum total length in males 378 mm, in females 657 mm.

Comparisons.

Bothriechis torvus is compared to other species of the genus previously subsumed under B. schlegelii sensu lato (differences summarized in Table 2 ). It differs from all of them by having three raised and triangular supraciliary scales, anterior dorsal head scales keeled, a high number of canthals (3-8) and interoculolabials (6-18), thin pink dorsal bands, and entirely pale white belly. Bothriechis torvus differs from B. schlegelii sensu stricto by having anterior dorsal head scales keeled, 3-8 canthals (rather than 1-3), bands pink or red (rather than black or dark brown; Fig. 15 ), ventral surfaces entirely white, a higher number of ventrals in both males and females, smaller body size, and smaller basal hooks on the hemipenial body (Fig. 16 ). Bothriechis torvus is sympatric with B. nigroadspersus along the Serranía de Pirre, Darién province, Panama (lime green shade in Fig. 3 ). The two species differ in coloration (Figs 5 , 15 ). Bothriechis torvus has dorsal bands (vs opposing kidney shaped marks), three broad and triangular enlarged supraciliary scales (vs two thin and spinelike), a lower number of ventral scales, and lateral surface of the hemipenial body and lobes more heavily packed with larger spines (Fig. 16 ). Bothriechis torvus resembles B. rahimi sp. nov., but this other species occurs south of the known distribution of B. torvus and is characterized by having a lower number of ventrals, enlarged spinelike supraciliary scales, faint dorsal banding, and presence of the yellow morph. Bothriechis torvus differs from B. khwargi sp. nov. by having pink bands (bands absent or dark vertebral blotches in B. khwargi sp. nov.).

Hemipenial morphology.

(n = 1; Fig. 16 ) Everted and inflated, the organ is deeply bilobed, calyculate and noncapitate; hemipenial lobes cylindrical, but tapering towards the capitulum; in sulcate and asulcate views, lobe crotch ornamented with densely packed spines that become larger distally; sulcus spermaticus centrolineal, bifurcate and with walls strongly defined, bifurcation occurs below bilobation point and proximal to the base of the hemipenial body; sulcus spermaticus branch runs to lobe tips; distal half of each hemipenal lobe densely ornamented with small calyces with defined spinulate edges. In sulcate view, hemipenial body surface spinulate medially with enlarged and strongly calcified lateral basal hooks followed by rows of smaller obliquely arranged mesial spines that become gradually smaller towards each lobe’s capitulum; each hemipenial lobe ornamented with mesial and lateral spines about 1/5 the size of the large basal hooks; the spines in each lobe are replaced distally by calyces with strongly spinulate edges. In lateral view, hemipenial body and lobes non-spiculate but with rows of spines; distal half of lobes strongly calyculate. In asulcate view, the center of hemipenial body is nude to barely spiculate; hemipenial lobes ornamented with 2 rows of smaller spines (about 1/3 the size of the lateral basal hooks) that decrease in size towards the lobe crotch.

Natural history.

Bothriechis torvus is an arboreal snake that inhabits evergreen lowland/foothill forests. We have found vipers of this species active at night crawling on ferns, tree branches, and trunks from 1.8 to 5 m above the ground or during the day perched on arboreal vegetation up to 3.5 m above the ground. Specimens from Cerro Sapo and Pirre Mountain ranges, eastern Panama, were found in a cloud forest consisting predominantly of trees covered with moss and a large variety of understory and midstory bromeliads. In captivity, TH 145 (Fig. 15c ) and another specimen from Morromico, Chocó department, Colombia, consumed lizards ( Anolis and Lepidodactylus ) and frogs ( Craugastor and Pristimantis ).

Venom.

Prezotto-Neto et al. (2016) studied the composition of the venom of specimens of Bothriechis torvus from Vegachi, Antioquia, and found that its properties differ drastically from specimens of B. nigroadspersus from Costa Rica. When compared to the latter, the venom of B. torvus was found to be less edematous, hemorrhagic, and lethal (LD50 estimated as 9.24 mg/kg vs 5.60 mg/kg).

Distribution.

Bothriechis torvus is known from at least 37 localities (listed in Suppl. material 3) along the Chocó and Río Magdalena valley regions of northern Colombia and extreme southeastern Panama. The species occurs over an area of approximately 61,466 km2 and has been recorded at elevations 61-1,413 m above sea level (Fig. 3 ). The ENM suggests the distribution is not continuous across the valley of the Río Atrato (see Discussion).

Etymology.

The specific epithet torvus is a Latin word meaning “fierce.” It refers to the protruding supraciliary scales, which according to Andrés Posada Arango, give this species an " air féroce.”

Conservation status.

We consider Bothriechis torvus to be included in the Least Concern category following IUCN Red List criteria ( IUCN 2012) because the species is distributed over a region that holds large areas of continuous unspoiled forest. Based on the species distribution model presented in Fig. 3 in combination with maps of vegetation cover of Colombia ( IDEAM 2014) and Panama ( CATHALAC 2011), we estimate that more than half (~59%) of the species’ forest habitat is still standing. Unfortunately, vast areas of the Chocó rainforest in northern Colombia and towards central Panama have already been converted to pastures ( Myers et al. 2000). However, B. torvus occurs over an area greater than 50,000 km2 and is presumably not declining fast enough to qualify for a threatened category.

Figures

Figure 3. Distribution of species of Bothriechis previously subsumed under B. schlegelii sensu lato. Each colored area is a geographic representation of the suitable environmental conditions for one of the clades recovered in the phylogeny of Fig. 2. Lime green shade in southeastern Panama represents overlap between between B. nigroadspersus and B. torvus.

Figure 5. Photographs of some specimens of Bothriechis nigroadspersus in life. a. Adult female from a private collection in Costa Rica; b. MHCH 3269 adult from Guabito, Bocas del Toro province, Panama; c. Subadult from Parque Nacional Gandoca Manzanillo, Limon province, Costa Rica; d. Adult from a private collection in Costa Rica; e, f. Juveniles from Parque Nacional Gandoca Manzanillo, Limon province, Costa Rica; g. MHCH 3268 adult female from Porton, Chiriqui province, Panama; h. MHCH 3266 adult female from Chucanti Reserve, Darien province, Panama; i. Subadult from Parque Nacional Gandoca Manzanillo, Limon province, Costa Rica; j. Adult female from a private collection in Costa Rica; k. FP 001 from Cerro Gaital, Cocle province, Panama; l. MHCH 3267 juvenile male from Chucanti Reserve, Darien province, Panama. Photos by Jose Vieira.

Figure 15. Photographs of some specimens of Bothriechis torvus in life. a. Adult and b. Juvenile (same individual) from Morromico Reserve, Choco department, Colombia; c. TH 145 adult female from Morromico Reserve, Choco department, Colombia; d. Adult and e. Juvenile from Uraba, Antioquia department, Colombia. Photos by Jose Vieira.

Figure 16. Hemipenial architecture of Bothriechis torvus in sulcate, lateral, and asulcate views. ICN 0421 from Valle del Cauca department, Colombia. Photos by Duvan Zambrano.