Bolitoglossa bolanosi, Arias & Chaves & Parra-Olea, 2023

Arias, Erick, Chaves, Gerardo & Parra-Olea, Gabriela, 2023, A new species of salamander (Caudata: Plethodontidae: Bolitoglossa) from the subalpine rain páramo of the Cordillera de Talamanca, Costa Rica, Amphibian & Reptile Conservation (e 327) 17 (1), pp. 143-160 : 146-154

Bolitoglossa bolanosi sp. nov.

Bolaños’ Web-footed Salamander

( Figs. 4–6 )

urn:lsid:zoobank.org:act:3F7E0D7E-906F-4FCD-B4CE-0A48F134DEA1

Holotype. UCR 22965, an adult male from Costa Rica: Provincia de Puntarenas: Cantón de Buenos Aires: Distrito de Buenos Aires: the summit of Cerro Arbolado , Parque Internacional La Amistad , (9.320º, -83.216º; 2,600 m asl), collected by Erick Arias and Omar Zúñiga on 19 October 2016.

Paratopotype. UCR 22964, a subadult male, same data as holotype.

Paratypes. UCR 22424, an adult male; UCR 22423, an adult female; UCR 22425, a subadult female; UCR 22422 and UCR 22426, subadult males; and UCR 22427, a juvenile from Costa Rica: Provincia de Puntarenas: Cantón de Buenos Aires: Distrito de Buenos Aires : the summit of Cerro Utyum, Parque Internacional LaAmistad, (9.323º, -83.187º; 2,870 m asl), collected by Erick Arias, Gerardo Chaves, Olmer Cordero, and Omar Zúñiga on 30 March 2015 . UCR 22421, an adult female from Costa Rica: Provincia de Limón: Cantón de Talamanca: Distrito de Telire: the summit of Cerro Utyum , Parque Internacional La Amistad , (9.333º, -83.180º; 2,913 m asl), collected by Erick Arias, Gerardo Chaves, Olmer Cordero, and Omar Zúñiga on 30 March 2015 . UCR 22745, an adult male; UCR 22741–4, adult females; and UCR 22746, a juvenile from Costa Rica: Provincia de Puntarenas: Cantón de Buenos Aires: Distrito de Buenos Aires: the summit of Cerro Hakú, Parque Internacional La Amistad , (9.322º, -83.203º; 2,660 m asl), collected by Erick Arias and Omar Zúñiga on 28 December 2015 . UCR 24245, an adult female; UCR 24246, an adult male; UCR 24247, a subadult male; and UCR 24248, a juvenile from Costa Rica: Provincia de Puntarenas: Cantón de Buenos Aires: Distrito de Buenos Aires: the summit of Cerro Dúrika, Parque Internacional La Amistad , (9.374º, -83.303º; 3,240 m asl), collected by Omar Zúñiga on 13 January 2016 .

Generic Placement. Assigned to the genus Bolitoglossa due to having 14 costal grooves and lacking a sublingual fold, and to the subgenus Eladinea based on the molecular evidence presented herein.

Diagnosis. The combination of the following characteristics can be used to distinguish Bolitoglossa bolanosi from the other described species of the genus Bolitoglossa : (1) having broad hands and feet, with the distal phalanges on the fingers and toes free of palmar and plantar tissue; (2) dorsal coloration highly variable, rarely black brownish uniform and usually mottled with yellow spots, but never with red on hind limbs or forelimbs; and (3) 16S and cyt b mtDNA distances.

Comparisons. Bolitoglossa bolanosi is differentiated from members of the subgenus Eladinea by its 16S and cyt b mtDNA distances. Since B. bolanosi is only known to occur in Costa Rica and molecular evidence strongly supports it forming part of the Bolitoglossa subpalmata species group within the subgenus Eladinea , phenotypic comparisons are presented here only concerning the members of that clade ( B. bramei , B. gomezi , B. gracilis , B. kamuk , B. pesrubra , B. splendida , B. subpalmata , and B. tica ), which are endemic to mountain ranges of Costa Rica and western Panama.

Contrasting characteristics for Bolitoglossa bolanosi are presented in parentheses. Bolitoglossa bramei Wake et al., 2007 can be distinguished from B. bolanosi by having a rounded snout in males (snout strongly truncated in males); dorsal ground color dark brown to brownish red, usually with darker mottling or frosting of silvery-gray (dorsal ground color black to dark brown, usually with mottling or blotches of yellow to red). Bolitoglossa gomezi Wake et al., 2007 has fore limbs relatively shorter, FLL/SL 20% (FLL/SL 22.3–26.1%), snout rounded (snout truncate in males). Bolitoglossa gracilis Bolaños et al., 1987 has dorsum yellowish ground color and a distinct dark midventral stripe (dorsum variable but never with yellowish ground color and never with a distinct midventral stripe). Bolitoglossa splendida Boza-Oviedo et al., 2012 has a shiny black dorsum with a bright reddish-orange broad dorsal band extending from the back of the head to the base of the tail, and with bright enamel-yellow spots scattered along the lateral and ventrolateral surfaces (dorsum variable but none with a reddish dorsal band extending from the head to the tail). Bolitoglossa subpalmata (Boulenger, 1896) has forelimbs that are relatively shorter, FLL/SL 18.7–23.1% (FLL/SL 22.3–26.1%). Bolitoglossa tica García-París et al., 2008 has dorsal ground color usually a uniform reddish brown with a darker tail, rarely with mottling or blotches contrasting (dorsal ground color black to dark brown, usually with yellow to red mottling or blotchy contrasting); prominent whitish spots on the venter (venter without whitish spots).

Bolitoglossa bolanosi differs from its closest relatives as follows: Bolitoglossa kamuk Boza-Oviedo et al., 2012 is smaller and more slender with mean SL 34.6–38.4 mm (larger and robust, SL = 39.43–50.01 mm); internarial distance relatively shorter, IND/HeW = 0.26±0.05 (internarial distance relatively longer, IND/HeW = 0.31±0.05); shorter tail TL/SL 98–99% (tail long, TL/SL 102.3–117.2%); dorsal ground color relatively uniform, orange to black (dorsal ground usually mottled or blotchy); males with rounded snout (snout strongly truncated in males). Bolitoglossa pesrubra (Taylor, 1952) has hands and feet more webbed ( Fig. 5C–D ), usually less than the ultimate phalange free (with at least the ultimate phalange free beyond the interdigital tissue margin, Fig. 5A–B ); has red color on forelimbs and usually on hind limbs (dorsum variable but never with red on hind limbs or forelimbs). Hands relatively wider, HaW/HeW = 0.61±0.07 (hands narrower, HaW/HeW = 0.56±0.06).

Description of holotype. Adult male having a SL of 49.05 mm ( Fig. 4 ). Head slightly wider than neck and shoulders (HeW 7.3 mm, NeW 6.2 mm, ShW 7.1 mm), with the greatest width of the head just posterior to the articulation of the jaws; truncate in dorsal outline and rounded to truncate in profile; snout moderate (SnL 3.4 mm, 6.9% of SL), with nearly terminal non-protruding small nostrils (LNH 0.6 mm, RNW 0.4 mm) directed anterolaterally; internarial area convex in dorsal outline. Snout protruding beyond the anterior margin of the lower lip in lateral view. Eyes relatively large (EW = 92% of SnL), weakly protruding beyond the dorsal and ventral outline of the head, directed anterolaterally, with a distinct suborbital groove. Top of head flat and smooth, tapering slightly toward anterior terminus, lacking contrasting interorbital or other dermal structures. Canthus rostralis weakly rounded; intercanthal area flat to slightly convex; and loreal region slightly concave. Evident cirri (nasolabial protuberances) on tip of snout; nasolabial grooves start at ventrolateral margins of nares and terminate in a cirrus. Gular fold is well-defined, starting on the dorsolateral portion of the neck, below the postorbital groove. Evident mental gland is visible under the skin of the anterior intermandibular region.

Arms relatively long and slender (FLL = 12.6 mm, 25.7% of SL), without noticeable hypertrophied forearm compared to the upper arm. Hands well-developed and slender (HaL = 5.4 mm, 40.9% of VGS; HaW = 4.8 mm, 65.8% of HeW). Fingers II, III, and IV protrude freely, with at least the ultimate phalange free beyond interdigital tissue margin (LF2 2.3 mm, LF3 3.0 mm; Fig. 5 ). Tips of fingers rounded; terminal pads weakly discernible on the ventral surfaces of fingers. Relative lengths of fingers on right hand: I <IV <II <III.

Legs moderately long and slender (HLL 13.1 mm, 26.7% of SL). Feet well-developed and slender (FoL 5.5 mm, 41.7% of VGS; FoW 5.7 mm, 78.1% of HeW). Toes II, III, IV, and V protruding freely beyond interdigital tissue margin (LT2 1.9 mm, LT3 2.7 mm), toe I with minimal indentation at interdigital spaces. Toe III is most free of interdigital tissue, with about the entire distal phalanx protruding. Tips of toes rounded; terminal pads weakly discernible on ventral distal surface of toes. Relative lengths of toes on right foot: I <V <II <IV <III.

Body subcylindrical (slightly wider than high) in cross-section, and relatively slender (TW = 6.0 mm; TW = 26.5% of AGL). Between the axilla and groin, 11 costal grooves are visible, 13 if counting axillary and inguinal grooves; costal grooves are most visible on ventral and lateral portions of the body. Adpressed limbs separated by one costal fold; 12 costal folds total between axilla and groin. The tail is long, cylindrical in cross-section, with an evident constriction at the base, and some caudal grooves discernible on the anterior portion of the tail. The skin on the surfaces of the head, body, limbs, and tail is smooth.

Coloration in life. The ground color of dorsal surfaces of the head, trunk, tail, hind limbs, and forelimbs is brownish black to brownish violet with numerous fine lighter patches of chromatophores scattered throughout the dorsal surface, especially concentrated on the head. The head and hindlimbs are lighter than the trunk. A pair of irregular dorsolateral stripes, which run from the tail base to the intercanthal area crossing the superior eyelids, are formed by yellowish-bronze blotches. The iris is bright dark bronze with a dark brownish-black reticulation. The upper surfaces of the arms are lighter than the trunk, pinkish brown, with orange blotches in the proximal portion of the humerus and on the ventrolateral surface of the ulna. The upper surface of the legs is similar in color to the trunk, uniform brownish black, except in the foot which is paler. The dorsal and dorsolateral surfaces of the tail are nearly uniform brownish black.

The ventrolateral surfaces of the body, tail, hindlimbs, and forelimbs are lighter than the dorsal surface. The gular surfaces are paler than the venter, consisting of lighter brown with a paler blotch on the anterior part, the mental gland. The ventral surface of the trunk and the tail are slightly lighter than the dorsal surface. The ventral surfaces of the arms and legs are lighter than the dorsal surfaces with irregular orange blotches. The palmar and plantar surfaces are light brown with black chromatophores.

Coloration in ethanol. After more than seven years in ethanol (70%), the overall coloration of the holotype has darkened throughout and contains a principal dark brown-blackish tone.

Measurements (in mm), limb interval, and percentages of the holotype. SL 49.05; TL 57.5; ShW 7.1; HeW 7.3; NeW 6.2; EW 3.2; SnL 3.4; JSL 8.2; LGFS 12.9; LNH 0.6; RNW 0.4; IND 3.1; NLP 1.1; ICD 3.9; HLL 13.1; FLL 12.6; TW 6.0; VGS 13.2; FSL 15.2; UHL 9.0; AGL 22.8; VL 4.9; HaW 4.8; HaL 5.4; LF2 2.3; LF3 3.0; WF3 1.0; FoW 5.7; FoL 5.5; LT2 1.9; LT3 2.7; WT3 0.9. Limb interval 1. Measurements in relative percentages: VGS/ SL 26.9%; IND/HeW 42.5%; AGL/SL 46.5%; HeW/SL 14.9%; HeW/AGL 32.0%; SnL/ HeW 46.6%; LNH/HeW 8.2%; LNH/SL 1.2%; RNW/HeW 5.5%; RNW/SL 0.8%; HLL/SL 26.7%; FLL/SL 25.7%; HaL/VGS 40.9%; FoL/ VGS 41.7%; HaW/HeW 65.7%; FoW/HeW 78.1%; LT2/ FoL 34,5%; LF2/HaL 42.6%; WT3/FoW 15.8%; WF3/ HaW 20.8%.

Noteworthy variation. The female paratypes (UCR 22421 and UCR 24245) have more rounded snouts, and much less defined and protruding cirri or nasolabial protuberances, which are sexually dimorphic features. In coloration, this species is extremely polymorphic, some individuals are almost uniform black, which is common in juveniles (UCR 22247, Fig. 6B ). The paratopotype (UCR 22964, Fig. 6A ) has the pair of dorsolateral stripes more vivid and continuous, the blotches in the upper eyelid are iridescent green; in addition, it has a band of pale orange from posterior head to tail, where it is suffused with the red of the tail. The presence of red on the tail is common; generally the red color in the proximal portion is only on the dorsal surface, but the tail becomes completely red in the distal portion. Several specimens showed a similar coloration morpho “mottled” ( Fig. 6C ), with ground color brownish black to reddish brown with numerous and irregular yellow to red blotches or spots; these specimens lack the dorsolateral stripes. The female UCR 24245 ( Fig. 6D ) has a striking coloration pattern formed by large yellow blotches about a brownish-black ground color; although less evident this specimen has the pair of dorsolateral stripes but the blotches are larger and suffused in the back.

Measurements (in mm), limb intervals, and percentages of the paratypes. SL 39.4–50.0; ShW 4.9–7.5; HeW 6.3–7.7; NeW 5.0–6.7; EW 1.8–3.2; SnL 2.4–3.4; JSL 6.0–8.2; LGFS 10.2–12.9; IND 1.7–3.1; NLP 0.7–1.1; ICD 2.9–3.9; HLL 9.9–13.1; FLL 8.9– 17.6; TW 5.2–9.2; VGS 9.6–13.2; FSL 11.4–15.2; UHL 6.8–9.0; AGL 18.6–26.4; VL 3.5–5.1; HaW 3.0–4.8; HaL 3.4–5.4; LF2 1.3–2.3; LF3 1.8–3.0; WF3 0.7–1.1; FoW 3.4–5.7; FoL 3.8–5.5; LT2 1.5–2.1; LT3 1.7–2.9; WT3 0.7–1.2. Limb intervals 3–5. Measurements in relative percentages: VGS/SL 23.4–26.9%; IND/HeW 25.8– 42.6%; AGL/SL 46.4–57.6%; HeW/SL 14.5–16.9%; HeW/AGL 25.2–35.7%; SnL/HeW 35.7–47.6%; HLL/ SL 24.6–26.8%; FLL/SL 22.3–26.1%; HaL/VGS 32.7– 40.5%; FoL/VGS 37.1–44.4%; HaW/HeW 48.0–66.3%; FoW/HeW 54.5–78.6%; LT2/HeW 24.1–31.9%; LT3/ FoW 46.7–63.0%; LT2/FoL 34.9–45.8%; LF2/HaL 29.3– 46.9%; WT3/FoW 15.5–24.1%; WF3/HaW 16.2–28.3%.

Etymology. The name “ bolanosi ” is a patronym honoring the Costa Rican herpetologist Federico Bolaños, and is used as a noun in the genitive case. We name this species after our dear friend in recognition of his scientific contributions to the knowledge of the herpetology of Costa Rica, as curator of the Herpetology section at Museo de Zoología of Universidad de Costa Rica, and as the mentor of most herpetologists present in the country.

Habitat and natural history observations. The habitat of Bolitoglossa bolanosi in the subalpine rain páramo is characterized by having a very short dry season (one to two months), annual precipitation ranging from 1,000 to 2,000 mm, and annual temperatures between 3 and 6 ºC. The páramo vegetation consists of extensive, deep moss mats, spongy soil, ferns, and small isolated trees with arboreal bromeliads. Bolitoglossa bolanosi was found within both moss and bromeliads. It also occurs in Montane rain forest which is dominated by Quercus covered with moss, with a great abundance of bryophytes and epiphytes. The type locality occurs in the Montane rain forest ( Bolaños et al. 2005; Holdridge 1967), characterized by a very short dry season (one to two months), an annual precipitation range of 2,200 to 4,500 mm, and annual temperatures from 6 to 12 ºC.

Very little is known about the natural history of B. bolanosi , but it is important to note that females guarding a clutch of eggs were found on Cerro Hakú (December 2015) and Cerro Dúrika (January 2016), both under moss on the floor. All specimens from Cerro Utyum were found within bromeliads at heights of> 3 m over the soil, despite active searches in the moss of the páramo. Unlike in the peaks Dúrika, Arbolado, and Hakú, the specimens were mainly found in the moss at <2 m over soil, despite active searches in the bromeliads at> 3 m above the ground (especially on Cerro Arbolado and Cerro Hakú). In the summit of Cerro Dúrika, B. bolanosi is very near (~ 4 km) to a site with B. pesrubra . In the summit of Cerro Utyum, it is to only ~ 7 km to a site with B. kamuk , and in this peak B. bolanosi is sympatric with an unnamed miniaturized salamander related to B. pygmaea . In addition, the type locality of B. splendida is only ~ 4 km from the site with B. bolanosi .

Distribution. The known distribution area of Bolitoglossa bolanosi is very small, restricted throughout to ~ 15 km on the summits of the peaks Dúrika, Arbolado, Hakú, and Utyum on the Cordillera de Talamanca ( Fig. 1 ). The altitudinal range of the new species is 2,550 –3,240 m asl. All the populations of the new species were found in primary vegetation (páramo and forest) and all are within a protected area, La Amistad International Park.

Conservation status. The conservation status of this species is uncertain; however, its known distribution range is small (<20,000 km 2) and all know populations are restricted to summits of peaks, sites that are highly vulnerable to forest fires and other effects of climate change. We suggest that it should be tentatively considered as Vulnerable (VU) following the IUCN (2017) category criteria.

Figures

Fig. 4. Holotype of Bolitoglossa bolanosi sp. nov. (UCR 22965) in life on a white background. Photograph by Erick Arias.

Fig. 5. Dorsal views of the hand and foot of the holotypes of (A–B) Bolitoglossa bolanosi sp. nov. (UCR 22965) and (C–D) B. pesrubra in preservation. Photograph by Erick Arias.

Fig. 6. In-life photographs of variations within Bolitoglossa bolanosi sp. nov. (A) Paratopotype male subadult UCR 22966, (B) paratype juvenile UCR 24247, (C) paratype adult female UCR 22421, and (D) paratype adult female UCR 24245. Photographs A and C by Erick Arias, B and D by Omar Zúñiga.

Fig. 1. (A) Map showing the known populations of the species within the Bolitoglossa subpalmata species group. (B) Map showing the localities for B. bolanosi sp. nov. and the species close to it in the páramo of the Cordillera de Talamanca. The open shapes indicate the historical data and the solid shapes indicate the localities with molecular data included herein.