Nototriton vereh, Kubicki & Reyes & Arias, 2022

Kubicki, Brian, Reyes, Aura & Arias, Erick, 2022, Revised taxonomy and distributions of Costa Rican moss salamanders (Caudata: Plethodontidae: Nototriton), with descriptions of new taxa, Zootaxa 5194 (4), pp. 451-496 : 470-475

Nototriton vereh sp. nov.

Vereh moss salamander

Holotype. UCR 23681 ( Figs. 7–9 ), an adult female from Costa Rica: Provincia de Cartago: Cantón de Turrialba: Distrito de Chirripó: a private property owned by Brian Kubicki and referred to as the Río Vereh Cloud Forest Reserve , 1400 m a.s.l., collected by Brian Kubicki on 15 October 2016.

Paratypes. UCR 23682, an adult female from Costa Rica: Provincia de Limón: Cantón de Turrialba: Distrito de Chirripó : moss on bank of road between Jicotea and Río Vereh, ca. 1250 m a.s.l., collected by Brian Kubicki in the company of Aura Reyes on 2 November 2013 . UCR 23683, an adult male from Costa Rica: Provincia de Cartago: Cantón de Turrialba: Distrito de Chirripó : edge of road between Bajo Pacuare and Grano de Oro, ca. 1250 m a.s.l., collected by Brian Kubicki, in the company of Aura Reyes, on 13 April 2013 ; UCR 23684, an adult male: same locality data as UCR 23683, but collected by Brian Kubicki, in the company of Aura Reyes, on 21 March 2013 .

Generic Placement. Assigned to the genus Nototriton due to having fewer than 14 costal grooves, reduced manus and pes that are longer than wide, and the molecular evidence (16S, COI, and cyt b mtDNA distances) presented herein.

Subgeneric Placement. Nototriton vereh is further assigned to the subgenus Taylorotriton due to the combination of its known geographic distribution (endemic to the central Caribbean region of Costa Rica), its tiny hands and feet that are pad-like in appearance, with at the most the distal phalanx on each digit protruding in a bluntly pointed tip beyond the fleshy palmar and plantar tissue, and again the molecular evidence (16S, COI, and cyt b mtDNA distances) presented herein.

Diagnosis. The combination of the following characteristics can be used to distinguish Nototriton vereh from the other described species of the genus Nototriton : (1) having tiny hands and feet, with at the most only the distal phalanges on the fingers and toes free of palmar and plantar tissue; (2) large nostril openings, greater than 0.25 mm in height (Fig. X); (3) 16S, COI, and cyt b mtDNA distances.

Comparisons. Since Nototriton vereh is only known to occur within Costa Rica and the phenotypic and molecular evidence presented herein strongly supports it forming part of the newly proposed Taylorotriton subgenus, the phenotypic comparisons presented are only with respect to other members of that subgeneric taxon (i.e. N. richardi , and N. tapanti ).

Contrasting characteristics for Nototriton vereh are presented in parentheses. Nototriton richardi ( Taylor, 1949) can be distinguished from N. vereh by having relatively narrower feet, average FoW = 0.97 mm (average FoW = 0.85 mm); shorter hind limbs, average HLL = 3.7 mm and HLL = 15.7–19.5 % of SL (longer hind limbs, average HLL = 4.1 mm and HLL = 18.0–21.0 % of SL). Nototriton tapanti Good & Wake, 1993 has wider hands and feet, average HaW = 0.9 mm, HaW = 24.1–29.7 % of HeW, average FoW 1.1 = mm, FoW = 31.0–35.1 % of HeW (narrower hands and feet, average HaW = 0.7 mm, HaW = 23.3–27.6 % of HeW, average FoW 0.9 = mm, FoW = 26.7–32.1 % of HeW).

Description of holotype. Subadult to adult female having a SL of 18.6 mm. Head slightly wider than neck and shoulders (HeW 2.9 mm, NeW 2.5 mm, ShW 2.5 mm), with greatest width of head just posterior to the articulation of the jaws; snout raised anterodorsally, spadate to rounded in dorsal outline, and rounded in profile; snout relatively short (SnL 0.6 mm, 3.2 % of SL), with nearly terminal non-protruding large nostrils (LNH 0.28 mm, RNW 0.22 mm) directed anterolaterally; internarial area convex in dorsal outline. Eyes relatively large (EW = 183 % of SnL), weakly protruding beyond dorsal and ventral outline of 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. No obvious cirri (nasolabial protuberances), but nasolabial grooves weakly discernible on tip of snout; nasolabial grooves start at ventrolateral margins of nares and extend ventrally, with a slight outward orientation, and terminate prior to reaching upper lip margin. Gular fold well-defined, starting on dorsolateral portion of neck, below postorbital groove, wrapping around posteriolateral section of head at a slightly anterior angle and crossing venter as a smooth anterior-oriented curve. Nuchal grooves very weakly evident, starting above postorbital groove and converging medially at occiput. Postorbital grooves weakly evident, starting at the posterior corner of eyes and traveling horizontally along the inferior margin of parotoid glands, terminating at gular fold on the lateral portion of neck. Horizontal mandibular groove moderately defined, starting at corner of mouth and extending horizontally to vertical portion of mandibular groove. Mandibular groove not a single continuous structure, but rather two independent structures on each side of head. Vertical portion of mandibular grooves starting along the inferior margins of postorbital grooves and traveling vertically to gular region, terminating at or just medially of intersections with inner mandibular grooves. Inner mandibular groove not a single continuous structure, but rather two independent and laterally postioned structures. Inner mandibular grooves moderately evident, starting at anterior termini or margin of mandibular grooves, running medially parallel to mandibular bones, becoming indiscernible near anterior tip of lower jaw. Pair of weak, but discernibly raised parotoid glands present on dorsolateral margin of head between orbits, postorbital grooves, and occiput. Snout protruding beyond anterior margin of lower lip in lateral view. No mental gland visible under skin of anterior intermandibular region.

Arms relatively short and slender (FLL = 3.3 mm, 17.7 % of SL), without noticeable hypertrophied forearm compared to upper arm. Hands very small and slender (HaL = 0.9 mm, 22.5 % of VGS; HaW = 0.8 mm, 27.6 % of HeW). Fingers II and III protruding slightly beyond interdigital tissue margin (LF2 0.31 mm, LF3 0.19 mm), fingers I and IV with minimal indentation at interdgitial spaces, barely receding proximally beyond tips of latter mentioned digits. Finger III most free of interdigital tissue, with about entire distal phalanx protruding. Tips of fingers rounded (fingers I, II, IV) to acutely rounded (Finger III). Terminal pads weakly discernible on ventral surface of fingers. Palmar surfaces appearing to be smooth overall, but with an evident dermal crease extending transversally along proximal margin of tip of Finger III. Dorsal surfaces of hands with discernible interdigital grooves that start at interdigital tissue margins and cross metacarpal region. Relative lengths of fingers on right hand I <IV <II <III.

Legs relatively short and slender (HLL 3.9 mm, 21.0 % of SL), with lower leg being slightly thicker than upper leg. Feet small and slender (FoL 1.2 mm, 30.0 % of VGS; FoW 0.9 mm, 31.0 % of HeW). Toes II and III protruding slightly beyond interdigital tissue margin (LT2 0.40 mm, LT3 0.22 mm), toes I, IV, and V with minimal indentation at interdgitial spaces, barely receding proximally beyond tips of latter mentioned digits. Toe III most free of interdigital tissue, with about entire distal phalanx protruding. Tips of toes rounded (toes I, II, IV, V) to accutely rounded (Toe III). Terminal pads weakly discernible on ventral distal surface of toes, especially on toes II, III, and IV. Plantar surfaces appearing to be smooth overall, but with some evident dermal creases. Dorsal surfaces of feet with discernible interdigital grooves that start at interdigital tissue margins and cross metatarsal region. Relative lengths of toes on right foot I <V <II <IV <III.

Body subcylindrical (slightly wider than high) in cross section, and relatively robust (TW = 2.4 mm; TW = 23.5 % of AGL). Between axilla and groin, 11 costal grooves visible, 13 if counting axillary and inguinal grooves; costal grooves most visible on ventral and lateral portions of body. Adpressed limbs separated by 4 costal folds; 12 costal folds total between axilla and groin. Slight middorsal depression extends longitudinally along length of body, starting at base of head (occiput) and becoming indiscernible on anterior portion of tail. Tail long, cylindrical in cross section, lacking an evident constriction at base, and evenly tapering to pointed terminus; in life, some caudal grooves discernible on anterior portion of tail. Skin on surfaces of head, body, limbs, and tail smooth.

Coloration in life. The ground color of the dorsal and dorsolateral surfaces of the head and trunk consisted of a mixture of reddish-brown earthy tones. Secondary coloration on the dorsal and dorsolateral surfaces of the head and trunk consisted of larger irregular black markings (especially concentrated along the dorsolateral region of the trunk and dorsal surface of the head), numerous closely spaced darker chevron marks visible along upper dorsum of the trunk, and numerous fine to very fine pale orange to white patches of chromatophores scattered randomly throughout the dorsal surface. The iris was bright orange with a dark brownish-black reticulation.

The upper surfaces of the arms and legs were a mixture of chromatophore patches of irregular shapes and sizes, ranging in color from pale orange, pinkish-orange, dark brown, and black. Additionally, there were some fine to very fine patches of white chromatophores scattered randomly throughout the dorsal surface of the limbs.

The dorsal and dorsolateral surfaces of the tail were nearly uniform reddish-orange, with some fine to very fine patches of white chromatophores scattered randomly throughout.

The ventrolateral surfaces of the body and tail were contrasted from the superior surfaces by consisting of a concentration of fine white or pale markings on a dark gray background.

The ventral surfaces of the head, body, limbs, and tail were pale brown to gray with numerous fine to very fine white spots and irregular markings scattered throughout. Just posterior to the cloaca, there was a concentration of contrasting pale orangish spots and irregular markings. The ventral surfaces of the limbs and gular patch were slightly paler in comparison to the ventral surfaces of the body and tail. The palmar and plantar surfaces were pale grayish-white.

Coloration in ethanol. After more than 5 years in ethanol (70%), the overall coloration of the holotype has darkened throughout and contains a principal dark brown tone.

Measurements (in mm), limb interval, and percentages of the holotype. SL 18.6; ShW 2.5; HeW 2.9; NeW 2.5; EW 1.1; SnL 0.6; JSL 2.5; LGFS 4.1; LNH 0.28; RNW 0.22; IND 0.7; NLP 0.4; ICD 1.4; HLL 3.9; FLL 3.3; TW 2.4; VGS 4.0; FSL 5.4; UHL 2.2; AGL 10.2; VL 1.2; HaW 0.8; HaL 0.9; LF2 0.31; LF3 0.19; WF3 0.22; FoW 0.9; FoL 1.2; LT2 0.4; LT3 0.22; WT3 0.22. Limb interval 4. Measurements in related percentages: VGS/SL 21.5 %; IND/HeW 24.1 %; AGL/SL 54.8 %; HeW/SL 15.6 %; Hew/AGL 28.4 %; SnL/ HeW 20.7 %; LNH/HeW 9.7 %; LNH/SL 1.5 %; RNW/HeW 7.6 %; RNW/SL 1.2 %; HLL/SL 21.0 %; FLL/SL 17.7 %; HaL/VGS 22.5 %; FoL/VGS 30.0 %; Haw/HeW 27.6 %; FoW/HeW 31.0 %; LT2/FoL 33.3 %; LF2/HaL 34.4 %; WT3/FoW 24.4 %; WF3/HaW 27.5%.

Noteworthy variation. The male paratypes ( UCR 23683 and UCR 23684) had more truncate snouts, and much more defined and protruding cirri or nasalabial protruberances, sexually dimorphic features that are often observed among plethodontids, including bolitoglossines .

Measurements (in mm), limb intervals, and percentages of the paratypes. SL 20.8–22.8; ShW 2.4–2.5; HeW 2.6–3.0; NeW 2.3–2.5; EW 1.1–1.2; SnL 0.8–0.9; JSL 2.6–2.8; LGFS 4.4–4.9; LNH 0.25–0.28; RNW 0.22– 0.28; IND 0.6–0.8; NLP 0.3–0.5; ICD 1.3–1.5; HLL 4.1; FLL 3.5–4.1; TW 2.5–2.7; VGS 3.7–4.2; FSL 5.7–6.4; UHL 2.3–2.5; AGL 11.4–13.1; VL 1.5–1.7; HaW 0.7; HaL 1.0; LF2 0.28–0.40; LF3 0.19–0.25; WF3 0.22; FoW 0.8–0.9; FoL 1.2; LT2 0.31–0.40; LT3 0.22–0.28; WT3 0.22–0.23. Limb intervals 5–6. Measurements in related percentages: VGS/SL 17.1–19.2 %; IND/HeW 23.1–28.6 %; AGL/SL 54.8–57.5 %; HeW/SL 12.0–13.5 %; Hew/ AGL 21.0–24.6 %; SnL/HeW 26.7–32.1 %; LNH/HeW 9.3–10.0 %; LNH/SL 1.2–1.4 %; RNW/HeW 7.7–10.0 %; RNW/SL 1.0–1.3 %; HLL/SL 18.0–19.7 %; FLL/SL 16.2–18.8 %; HaL/VGS 23.8–27.0 %; FoL/VGS 28.6–32.4 %; Haw/HeW 23.3–26.9 %; FoW/HeW 26.7–32.1 %; LT2/HeW 7.7–10.0 %; LT3/FoW 20.6–25.6 %; LT2/FoL 25.8–33.3 %; LF2/HaL 28.0–40.0 %; WT3/FoW 24.4–28.8 %; WF3/HaW 31.4%.

Etymology. The specific epithet is a noun in apposition, and refers to the region where the holotype was collected, the upper catchment basin of the Vereh River.

Habitat and natural history observations. Nototriton vereh has been found to inhabit moss growing on the ground and on the lower sections of tree trunks (within a meter above the ground). One specimen ( UCR 23684) was found within a clump of moss that had fallen from a tree above; this moss had been on the ground for a while judging by its appearance, so it is highly unlikely that this individual had been living within the moss high up in the canopy. We feel that it is most likely that UCR 23684 was living within the terrestrial leaf litter and was taking diurnal refuge within the fallen moss clump when BK and AR discovered it. Two individuals ( UCR 23682 and UCR 23683) were found by BK and AR during the day within moss growing on the ground in highly disturbed roadside habitats. The holotype ( UCR 23681) was discovered by BK within a section of abandonded pasture in his private property referred to as the Rio Vereh Cloud Forest Reserve. The holotype was discovered during the day within a thick patch of moss (approximately 5 cm in thickness) growing on the lower trunk of a small tree, approximately 50 cm above the ground .

Distribution. Nototriton vereh is endemic to Costa Rica, and currently only known to inhabit a very small section of cloud forest within the Tropical Premontane Rainforest life zone ( Holdridge 1967) along the northern Caribbean foothills of the Cordillera de Talamanca. The known altitudinal range for N. vereh is from ca. 1250–1400 m a.s.l.

Figures

FIGURE 7. Holotype of Nototriton vereh sp. nov. in life on white background. Photograph by BK.

FIGURE 8. Dorsal, lateral, and ventral views of the body of the holotype of Nototriton vereh sp. nov. in preservation.Photograph by BK.

FIGURE 9. Dorsal views of the hand and foot and detail of the face of the holotype of Nototriton vereh sp. nov. in preservation. Photograph by BK.