Bolitoglossa chirripoensis, Klank & Chaves & Castro & Arias, 2025

Klank, Jeremy, Chaves, Gerardo, Castro, Kimberly & Arias, Erick, 2025, A new species of salamander of the genus Bolitoglossa (Caudata: Plethodontidae) from the highest massif of the Cordillera de Talamanca, Costa Rica, Zootaxa 5642 (5), pp. 427-450 : 436-440

Bolitoglossa chirripoensis sp. nov.

Chirripó Web-footed Salamander urn:lsid:zoobank.org:act:FC002F04-40A5-40D9-9607-98ED67DD1C28

( Figures 4–6 )

Holotype. UCR23302 ( Figs. 4–5 ), an adult male from Costa Rica: Provincia de San José: Cantón de Pérez Zeledón: Distrito de Rivas: in front of the Crestones peak, Parque Nacional Chirripó , (9.4566º N, - 83.5050º W, 3320 m elevation), collected by Gerardo Chaves, Jeremy Klank, and Kimberly Castro on 17 November 2019.

Paratypes. UCR23300 and UCR23301, adult females ( Fig. 6 ); same data as holotype .

Reference material. UCR11813–6, adult males from Costa Rica: Provincia de San José: Cantón de Pérez Zeledón: Distrito de Rivas: Chirripó peak, Parque Nacional Chirripó , (9.475º N, - 83.494º W, 3620 m elevation), collected by Federico Valverde-Bonilla on 31 May 1994 .

Generic Placement. Assigned to the genus Bolitoglossa due to having fewer than 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 chirripoensis from other described species of the genus Bolitoglossa (1) moderate body size (49.3–58.3 mm in adult) with limbs relatively short and robust, LI = 2.5–3.5; (2) broad head (HW 14.6–16.0 % of SL), barely differentiated from the trunk; (3) by having broad hands and feet, with the distal phalanges on the fingers and toes free of webbing; (4) dorsal coloration dark brown suffused with violet and with well-defined white to bronze blotches, tail with pale blotches, hind limbs paler than the dorsum but highly pigmented with dark specks; (5) 16S and cyt b mtDNA distances.

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

Contrasting characteristics for Bolitoglossa chirripoensis are presented in parentheses. Bolitoglossa bolanosi Arias et al. 2023 can be distinguished from B. chirripoensis by having a longer snout, SnL/HW 36.4–47.6 % (shorter snout, SnL/HW 26.9–36.2 %); longer tail TL/SL 102.3–117.2% (shorter tail, TL/SL 97.5–102.1%); dorsum variable in coloration but usually with an uniformly dark brown background (dorsum dark brown suffused with violet and with large white to bronze blotches); tail without pale blotches on a dark background (tail with pale blotches on a dark background). Bolitoglossa bramei Wake et al. 2007 has moderately protuberant eyes, which protrude beyond the lateral margin of the head in ventral view (smaller eyes which do not protrude beyond the lateral margin of the head in ventral view); hands and feet moderately webbed, fewer than the two distal-most phalanges of the longest digits free of webbing (two or more distal-most phalanges of the longest digits free of webbing); with more teeth, VT = 24–28, MT = 49–66 (fewer teeth, VT = 14–21, MT = 35–50). Bolitoglossa gomezi Wake et al. 2007 has a particularly well-differentiated head from the trunk (head barely differentiated from the trunk); is smaller and slender with SL = 29.3–54.3 mm (larger and robust, SL = 49.3–58.3 mm); has a longer tail TL/SL 93.0–119.0% (shorter tail, TL/SL 97.5–102.1%); forelimbs slender and relatively shorter, FLL/SL 20.0% (relatively robust forelimbs FLL/SL 23.0–23.5%); dorsum and tail coloration variable but usually without large white to bronze blotches (dorsum and tail dark brown suffused with violet and large white to bronze blotches). Bolitoglossa gracilis Bolaños et al. 1987 has a longer tail TL/SL 110.0–116.0% (shorter tail, TL/SL 97.5–102.1%); eyes moderate in size and relatively protuberant, which protrude beyond the lateral margin of head in ventral view (eyes smaller which not protrude beyond the lateral margin of head in ventral view); dorsum with a yellowish background coloration and a distinct dark midventral stripe (dorsum dark brown suffused with violet and large white to bronze blotches). Bolitoglossa kamuk Boza-Oviedo et al. 2012 is smaller and more slender with mean SL 34.6–38.4 mm (larger and robust, SL = 49.3–58.3 mm); has a longer snout, SnL/HW 35.8–40.0 % (shorter snout, SnL/HW 26.9–36.2 %); dorsum coloration orange to black, relatively uniform and without white to bronze blotches (dorsum dark brown suffused with violet and with large white to bronze blotches); tail without pale blotches on a dark background (tail with pale blotches on dark background). Bolitoglossa pesrubra ( Taylor 1952) has relatively smaller eyes, EW/JSL = 29.5±3.9 % (eyes larger, EW/JSL = 34.2–40.7 %); dorsum coloration variable but usually without white to bronze blotches on a dark brown background (dorsum dark brown suffused with violet and with large white to bronze blotches); tail without pale blotches on a dark background (tail with pale blotches on a dark background); in life usually with red forelimbs or paler in coloration and without dark specks, pale in alcohol (in life forelimbs with abundant dark specks, not whitish in alcohol). Bolitoglossa splendida Boza-Oviedo et al. 2012 has a shiny black dorsum with a broad and bright reddish-orange 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 dark brown suffused with violet and large white to bronze blotches); has more teeth, VT = 28, PMT = 6, MT = 57 (fewer teeth, VT = 14–21, PMT = 2–3, MT = 35–50). Bolitoglossa subpalmata (Boulenger 1896) has relatively smaller eyes, EW/JSL = 26.3– 35.1 % (larger eyes, EW/JSL = 34.2–40.7 %); head well differentiated from the trunk (head barely differentiated from the trunk); dorsal coloration usually with a pair of longitudinal stripes that go from the posterior margin of eye to the ingle or flanks, and which are a different color to the dorsum. When the stripes are not visible the individuals are dark brown to uniform black (dorsum dark brown suffused with violet and with large white to bronze blotches, without lateral stripes and flanks similar with similar coloration to the dorsum). Bolitoglossa tica García-París et al. 2008 has a particularly well-differentiated head from the trunk (head barely differentiated from the trunk); eyes moderate and relatively protuberant, which protrude beyond of lateral margin of the head in ventral view (eyes smaller, not protruding beyond the lateral margins of the head in ventral view); dorsal background coloration usually uniformly reddish brown with a darker tail, rarely with any mottling or contrasting blotches (dorsum dark brown suffused with violet and with large white to bronze blotches). Bolitoglossa pygmaea Bolaños & Wake 2009 has a very small size with adults having a SL of 23.6–32.6 mm (SL 49.3–58.2); Finger I reduced in size fingers in order of increasing length: I<II<IV<III (Fingers I <IV <II <III); dorsal coloration pale orange to dark brown with black patches (dorsum dark brown suffused with violet and with large white to bronze blotches). Bolitoglossa cerroensis ( Taylor 1952) is a medium to large salamander SL up to 114.5 mm (SL up 58.3 mm); less maxillary teeth, MT 22–23 (MT 35–50); body and limbs lavender brown in coloration, with multiple cream specks forming two diffused lateral lines along the dorsum (dorsum dark brown suffused with violet and with large white to bronze blotches).

Description of holotype. Adult male, SL 54.7 mm ( Figs. 4–5 ). Head barely differentiated from trunk (HW 8.0 mm, NeW 6.5 mm, SW 7.2 mm), with greatest width of the head transversely crossing posterior to the eyes; head rounded in dorsal outline and in profile; short snout (SnL 2.9 mm, 5.3 % of SL, Fig. 5E ), with nearly terminal and small nostrils (LNH 0.03 mm, RNW 0.1 mm) directed anterolaterally; internarial area slightly convex in dorsal outline. Snout protruding beyond anterior margin of lower lip in lateral view. Eyes small but protuberant (EW = 84.9 % of SnL), not protruding beyond dorsal and ventral outline of head, directed anterolaterally with a distinct suborbital groove. Teeth numerous; two premaxillary teeth in outer margin of upper lip, 19/19 maxillary teeth, 10/11 vomerine teeth. Well-defined superior eyelids, higher than top of the head in the interorbital area. Top of head flat and smooth, tapering slightly towards the anterior terminus, lacking contrasting interorbital or other dermal structures. Canthus rostralis weakly rounded; intercanthal area flat to slightly convex; loreal region flat. Evident cirri (nasolabial protuberances) on tip of snout; nasolabial grooves start at ventrolateral margins of nares and terminate in cirri. Well-defined groove from side of head crosses in front of jaw angle and passes across chin. Gular fold well-defined, starting on dorsolateral portion of neck, below the well-defined postorbital groove. Evident mental gland visible under the skin of the anterior intermandibular region, ovoid, 2.7 mm in diameter.

Arms are relatively short and robust (FLL = 12.6 mm, 22.9 % SL), without noticeable hypertrophied forearm compared to rest of arm. Hands relatively large and broad (HaL = 4.6 mm, 37.9 % VGS; HaW = 4.2 mm, 52.9 % HW; Fig. 5C ). Finger I is embedded in webbing tissue; the most-terminal phalanx of Fingers II and IV protrude freely from webbing; 22/3 phalanges protrude free from webbing beyond interdigital tissue margin in Finger III. Tip of fingers rounded; terminal pads discernible on ventral surface of fingers II–IV. Relative lengths of fingers on right hand I <IV <II <III.

Legs short and slightly robust (HLL 13.6 mm, 24.8 % SL). Feet broad (FoL 5.7 mm, 46.7 % of VGS; FW 5.4 mm, 66.9 % of HW; Fig. 5D ). Toe I with minimal indentation at interdigital spaces, terminal phalanx of Fingers II and V protrudes freely from webbing (T2 1.5 mm; T3 2.0 mm). Toe III is mostly free of webbing, with 21/2 distal phalanges protruding. Toe tips rounded; terminal pads discernible on ventral surface of toes II–V. Relative lengths of toes on right foot I <V <II <IV <III.

Body subcylindrical (slightly wider than high) in cross-section, relatively robust (TW = 7.6 mm; TW = 26.2 % AX). Skin on head, body, limbs, and tail surfaces smooth. Twelve costal grooves visible between the axilla and groin, 14 if counting axillary and inguinal grooves; costal grooves most visible on ventral and lateral portions of the body. Adpressed limbs separated by 2.5 costal folds; 13 costal folds in total between the axilla and groin. Tail length moderate (TL = 55.9 mm), cylindrical in cross-section, with evident constriction at base and with 24 caudal grooves discernible and with a small portion of the tail (9.5 mm) in which the grooves cannot be discerned.

Coloration in life ( Fig. 4 ). The background color of the dorsal surfaces of the head, trunk, tail, hind limbs, and forelimbs was dark brown suffused with violet with numerous bronze to gold specks. The speckles formed a pair of irregular dorsolateral bands extending from the upper eyelids to the anterior portion of the tail, where pale speckles become much less numerous. The tip of the head and lateral surface of the head paler, pinkish brown, and with numerous bronze speckles in the intercanthal region. The flanks were paler, becoming grayish-purple with bronze speckles. The iris was bright dark brown with a dark bronze reticulation. The upper surfaces of the arms and legs were paler but with numerous dark specks; the forelimbs were similar in coloration to the lateral surface of the head; the hindlimbs are similar in coloration to the flanks.

The trunk’s ventral surface was a dark brownish purple with a few whitish speckles on the lateral margin of the venter and tail. The chest and gular surface were paler than the venter, pinkish brown in coloration, and with numerous dark specks. The mental gland was very pale and cream colored. The ventral surface of the tail was similar to the rest of the ventral surface. The ventral surface of the arms was paler than the rest of the ventral surfaces. The ventral surface of the legs was similar in coloration to the venter. The palmar and plantar surfaces were dark-grayish purple with numerous chromatophores.

Coloration in ethanol ( Fig. 5 ). After five years in ethanol (70%), the overall coloration of the holotype has become darker throughout, mainly consisting of a dark gray to dull black. The trunk’s ventral surface is paler than the dorsal surface, now being a pale dark brown; it also has paler spots formed by lack of dark pigmentation. The tip and lateral surface of the head are paler than the rest of the dorsum. The dorsal surface of the forelimbs is paler than the dorsum but not very contrasting and is highly pigmented with dark specks. The gular surface is pale brown, strongly mottled with dark gray blotches.

Measurements (in mm), limb interval, and percentages of the holotype. SL 54.7; TL 55.9; SW 7.2; HW 8.0; NeW 6.5; EW 2.5; SnL 2.9; JSL 7.3; HL 12.8; LNH 0.3; RNW 0.1; IND 2.2; NLP 1.0; ICD 4.0; HLL 13.6; FLL 12.6; TW 7.6; VGS 12.1; SF 15.9; UHL 8.9; AX 29.0; VL 4.1; HaW 4.3; HaL 4.6; LF2 1.4; LF3 1.8; WF3 0.9; FW 5.4; FoL 5.7; T2 1.5; T3 2.0; WT3 0.9; Tail width 4.5; Tail depth (at base) 4.8. Limb interval 2.5. Measurements in related percentages: VGS/SL 22.2 %; IND/HW 27.4 %; AX/SL 52.9 %; HW/SL 14.7 %; HW/AX 27.8 %; SnL/ HW 36.2 %; LNH/HW 3.5 %; LNH/SL 0.5 %; RNW/HW 1.6 %; RNW/SL 0.2 %; HLL/SL 24.8 %; FLL/SL 23.0 %; HaL/VGS 38 %; FoL/VGS 46.7 %; HaW/HW 52.9 %; FW/HW 66.9 %; T2/FoL 26.7 %; LF2/HaL 31.3 %; WT3/ FW 16.4 %; WF3/HaW 21.6 %. Number of teeth: PMT 2, MT 19/19, VT 10/11.

Variation. This species shows little variation in coloration. The two adult female paratypes have broad blotches in the flanks, tail, and venter ( Fig. 6 ). In preservation, female UCR23300 has a ventral surface with similar coloration to the holotype, dark gray to dull black, but with large pale blotches in the venter and gular surface. The ventral surface of the female UCR23301 has a dark brown to tan coloration, and lateral surface of the head is paler than the dorsum. Female UCR23301 is very robust, TW/AX = 32.6%. The two paratypes have three premaxillary teeth, differing from the holotype (2). In one paratype, the number of costal interspaces between adpressed limbs was 3.5, differing from the holotype (2.5). The two females lack a mental gland. The two paratypes have eleven costal grooves visible between the axilla and the groin, 13 if counting axillary and inguinal grooves: 12 costal folds total between axilla and groin.

M easurements (in mm), limb intervals, and percentages of the paratypes. SL 49.3–58.3; TL 48.1–56.9; SW 6.5–7.5; HW 7.9–8.5; NeW 6.8–7.4; EW 2.2–2.8; SnL 2.1–2.8; JSL 5.4–7.8; HL 11.0–14.2; LNH 0.1–0.2; RNW 0.1–0.2; IND 2.2–2.5; NLP 0.8–0.9; ICD 4.1; HLL 12.8–13.0; FLL 11.4–13.7; TW 7.9–10.2; VGS 13.0–13.3; SF 14.0–16.7; UHL 7.9–9.6; AX 26.7–31.4; VL 4.3–5.3; HaW 4.3–5.0; HaL 3.8–5.1; LF2 1.3–1.7; LF3 1.5–1.8; WF3 0.9–0.9; FW 4.3–5.6; FoL 4.8–6.3; T2 1.4–1.5; T3 1.6–1.9; WT3 0.8–0.9; Tail width 4.2–4.7; Tail depth (at base) 4.4–5.4. Limb intervals 2.5–3.5. Measurements in related percentages: VGS/SL 22.4–27.0 %; IND/HW 28.4–29.4 %; AX/SL 54.0–54.1 %; HW/SL 14.7–16.0 %; HW/AX 27.2–29.6 %; SnL/HW 26.9–32.8 %; LNH/HW 1.6–2.2 %; LNH/SL 0.3 %; RNW/HW 1.3–2.6 %; RNW/SL 0.2–0.4 %; HLL/SL 21.9–26.3 %; FLL/SL 23.1–23.5 %; HaL/ VGS 28.7–39.4 %; FoL/VGS 36.2–48.0 %; HaW/HW 54.1–58.9 %; FW/HW 54.6–66.0 %; T2/FoL 22.1–30.9 %; LF2/HaL 24.5–45.0 %; WT3/FW 15.8–19.0 %; WF3/HaW 17.0–20.4 %. Number of teeth: PMT 3, MT 35–50, VT 14–19.

Etymology. The specific epithet, chirripoensis (from Chirripó + -ensis, a Latin suffix about location), comes from the locally indigenous language Cabécar word “Chirripó”, meaning “Land of eternal waters” (Spanish = “ Tierra de aguas eternas ”). The Chirripó National Park, the habitat of this species, include the Cerro Chirripó, the highest peak of Costa Rica (3821 m.a.s.l.).

Habitat and natural history observations. The habitat of Bolitoglossa chirripoensis is subalpine rain páramo forest ( Holdridge 1967; Bolaños et al. 2005), characterized by a very short dry season (one to two months), annual precipitation ranging of 1000–2000 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 chirripoensis was found actively foraging at night on rocks and grassy vegetation after an afternoon rain and was found active during cold misty conditions. On the summit of Cerro Chirripó, B. chirripoensis is very near (~ 2 km) to a site with B. pesrubra , both sites are separated by continuous páramo, implying sympatry between these species.

Distribution. This species is known only from the type locality in the páramo of the Cerro Chirripó at 3320– 3600 m.a.s.l. ( Fig. 1 ). This species was found in primary vegetation (páramo) within the protected area of Chirripó National Park.

Conservation status. The conservation status of this species is uncertain; however, its known distribution range is small (<20,000 km 2) and the only known population is restricted to the summit of Chirripó peak, a site highly vulnerable to forest fires and other effects of climate change. Additionally, the type locality is highly vulnerable to anthropogenic impacts due to being visited by thousands of tourists each year. We suggest that it should be tentatively considered as Vulnerable (VU) following the IUCN (2024) B1ab(iii) category criteria.

Figures

FIGURE 1. Map showing the localities for B. chirripoensis sp. nov. and the species of the Bolitoglossa subpalmata species group inhabiting the Cordillera de Talamanca in Costa Rica and western Panamá. The white shape corresponds to the rain páramo subalpine life zone. The open shape indicates the historical records and the solid shape indicates the localities with molecular data included herein.

FIGURE 4. Holotype of Bolitoglossa chirripoensis sp. nov. (UCR23303) in life. Photograph in situ (left) and on a white background (right). Photographs by JK.

FIGURE 5. Dorsal and ventral views of the body (A,B), ventral views of the hand (C) and foot (D), and detail of the face (E) of the holotype of Bolitoglossa chirripoensis sp. nov. (UCR23302) in preservation. Photographs by E.A.

FIGURE 6. In-life photographs of variation within Bolitoglossa chirripoensis sp. nov. A-B) paratype female adult UCR23301, C-D) paratype female adult UCR23301. Photographs by JK.