Bothriechis supraciliaris (Taylor, 1954)

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 supraciliaris (Taylor, 1954)

Figs 9 , 10 , 11

Bothrops schlegelii supraciliaris Taylor, 1954: 791. Holotype KU 31997 (Fig. 9 ), an adult female from mountains near San Isidro del General, San José province, Costa Rica.

Bothriechis supraciliaris Solórzano et al., 1998: 453-462.

Referred specimens.

all labeled Bothriechis supraciliaris in Suppl. material 1.

Standard English name.

Blotched Eyelash-Pitviper.

Standard Spanish name.

Bocaracá manchada.

Diagnosis.

Bothriechis supraciliaris is diagnosed based on the following combination of characters: (1) two or three raised and spinelike supraciliary scales; (2) anterior dorsal head scales smooth or barely keeled; (3) gular scales much smaller than chinshields; (4) 7-24 interoculolabials; (5) 4-5 canthals, most of which have raised triangular projections; (6) loreal in contact with preocular; (7) oropel morph extremely rare and with noticeably dark dorsal blotches on a yellowish background, rather than uniform golden-yellow; (8) reddish-brown irregular oval blotches or bands on dorsum; (9) opposing kidney shaped dorsal marks absent; (10) black speckles on dorsal scales absent; (11) black speckling on ventral surfaces usually absent or faint; (12) ventral surfaces not entirely white but yellowish anteriorly and light bluish-green posteriorly; (13) iris straw yellow with fine black speckles; (14) 21-23 dorsal scale rows at mid-body; (15) 144-150 ventrals in males, 139-148 in females; (16) maximum total length in males 382 mm, in females 583 mm.

Comparisons.

Bothriechis supraciliaris occurs near and is most similar to B. nigroadspersus . It can be identified from this other much more variable and widely distributed viper species primarily by having fewer ventral scales (Table 2 ), loreal in contact with preocular, anterior head scales smooth or barely keeled (vs keeled in B. nigroadspersus ), and by having reddish dorsal blotches or bands (Fig. 10 ). Lotzkat (2014) accurately pointed out that the two species differ in the dorsal pattern of the snout in contrastingly marked specimens. In B. supraciliaris there is a single anteriormost dorsal blotch centrally on the snout (Figs 9a , 10b-e ); in B. nigroadspersus , there are two paramedian blotches that may touch each other or be fused to form a short transverse band, but nevertheless remain discernible. Lotzkat (2014) also brings attention to the fact that specimens of B. supraciliaris have very little or no dark pigmentation on the ventral surfaces at least anteriorly in adult specimens (vs. extensive dark pigmentation throughout the venter which are not of the oropel morph in B. nigroadspersus ).

Hemipenial morphology.

(n = 2, Fig. 11 ) Everted and inflated, the organ is deeply bilobed, calyculate and semicapitate; hemipenial lobes cylindrical and with minimal separation between them; in sulcate and asulcate views, lobe crotch ornamented with densely packed spinules; sulcus spermaticus centrolineal, bifurcate and with walls weakly defined, bifurcation occurs below bilobation point and proximal to the base of the hemipenial body; sulcus spermaticus branch runs to lobe tips; distal one third of each hemipenal lobe densely ornamented by calyces with strongly defined spinulate edges. In sulcate view, hemipenial body surface nude medially, but with enlarged and strongly calcified lateral spines followed by 1-2 rows of smaller obliquely-arranged mesial spines that become gradually smaller towards each lobe’s capitulum; each hemipenial lobe ornamented with 1-2 mesial spines and 3-4 lateral spines, all about half the size of the larger lateral spines at the base of the hemipenial body; the spines in each lobe are replaced distally by calyces with strongly spinulate edges. In lateral view, hemipenial body and lobes with rows of spines, but otherwise smooth; distal 1/4 strongly calyculate. In asulcate view, the center of hemipenial body is nude except for a pair of large lateral spines; hemipenial lobes ornamented with 3-4 rows of smaller spines that decrease in size towards the lobe crotch.

Natural history.

Bothriechis supraciliaris is an arboreal snake that inhabits evergreen lower-montane forests, cloud forests, clearings with coffee and banana plantations, edges of farm fields, and rural gardens ( Campbell and Lamar 2004; Lotzkat 2014; Leenders 2019; Solórzano et al. 2021). Solórzano et al. (1998) and Solórzano (2004) report that individuals of B. supraciliaris are crepuscular, nocturnal, and tend to spend more time on the ground than other Bothriechis : they found 22 out of 25 individuals on the forest floor. However, all individuals seen by CLBA (n=10) were on bushes from 30 cm to 2 m above the ground. Another naturalist, Norberto Solano, with more than 80 sighting of the species, only found one on the ground (Norberto Solano, pers. comm. to CLBA). During the day, individuals have been found resting on the ground or at the base of trees and shrubs ( Solórzano 2004). Lotzkat (2014) and Batista et al. (2020) found individuals on low understory vegetation 0.5-2 m above the ground, either in ambush posture, crawling, or hanging from the tail. These authors also report that SMF 89764 was in the process of swallowing a comparatively large Craugastor fitzingeri . Solórzano et al. (1998) found mostly small forest-floor rodents in the stomach contents of four dissected specimens. They also report that specimens found in resting positions were curled in a loose circle and mostly on horizontal, wide surfaces.

Venom.

Lomonte et al. (2012) studied the venom of this species in Costa Rica and found that it has a potent hemorrhagic action, moderate myotoxicity, and very weak procoagulant activity. These authors estimated its lethal activity at LD50 6.04 mg/kg and found that the equine polyvalent ( Viperidae ) antivenom from Instituto Clodomiro Picado was able to neutralize the lethal effect of B. supraciliaris venom. The antivenom tested was produced from the plasma of equines immunized with a mixture of the venoms of Bothrops asper , Crotalus simus , and Lachesis stenophrys ( Lomonte et al. 2012).

Distribution.

Bothriechis supraciliaris is known from at least 24 localities (listed in Suppl. material 3) along the Pacific slopes of the Cordillera de Talamanca in southwestern Costa Rica and western Panama. The species occurs over an area of approximately 3,568 km2 and has been recorded at elevations 734-1,506 m above sea level (Fig. 3 ). We found that 100% of the predicted area of distribution of B. supraciliaris is included in the predicted area of distribution of B. nigroadspersus .

Etymology.

The specific epithet supraciliaris, which comes from the Latin words supra (meaning “above”) and cilium (meaning “eyelash”), refers to the prominent spinelike scales above the eye.

Conservation status.

We consider Bothriechis supraciliaris to be included in the Endangered category (instead of Least Concern; see Solórzano et al. 2021) following the IUCN criteria B1a, b (i, iii, iv) ( IUCN 2012), because the species’ extent of occurrence is estimated to be less than 5,000 km2 (Fig. 3 ) and its habitat is severely fragmented and declining in extent and quality due to deforestation. Although B. supraciliaris occurs in three protected areas ( Estación Biológica Las Cruces, Las Nubes Biological Reserve, and Parque Binacional La Amistad), the remaining localities where the species has been recorded (Suppl. material 3) are in forest patches surrounded by a matrix of pastures and small settlements. Based on the species distribution model presented in Fig. 3 in combination with maps of vegetation cover of Central America ( CATHALAC 2011), we estimate that nearly 37% of the forest cover throughout the species’ potential distribution area has been destroyed, mostly due to the expansion of the agricultural frontier.

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 9. Adult female holotype of Bothriechis supraciliaris KU 31997 in a. Dorsal and b. Ventral view. Photos by Hannah Som.

Figure 10. Photographs of some specimens of Bothriechis supraciliaris in life. a, d, e. From Reptilandia, Costa Rica; and b, c. From a private collection in Costa Rica. Photos by Jose Vieira.

Figure 11. Hemipenial architecture of Bothriechis supraciliaris in sulcate, lateral, and asulcate views. a. UTA R- 35246 from Jardin Botanico Las Cruces, Puntarenas province, Costa Rica; b. UTA R- 35192 from Jardin Botanico Las Cruces, Puntarenas province, Costa Rica. Photos by Eric N. Smith.