Nototriton kenorum, 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 : 477-481

Nototriton kenorum sp. nov.

Kens’ moss salamander

Holotype. UCR 23685 ( Figs. 11–13 ), an adult female from Costa Rica: Provincia de Limón: Cantón de Guácimo: Distrito de Guácimo: along edge of small road on the northern slopes of the Turrialba Volcano , approximately 9 kilometers south of Jiménez , ca. 750 m a.s.l., collected by Brian Kubicki on 10 May 2014.

Paratopotypes. UCR 23686 and UCR 23687, same collection data as the holotype . UCR 23688, same locality data as the holotype, but collected by Brian Kubicki on 23 July 2016 .

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 kenorum is assigned to the subgenus Nototriton due to its known geographic distribution (endemic to Costa Rica), its small hands and feet with the majority of the lengths of fingers II, III, and IV and toes II, III, IV, and V being free of extended palmar or plantar tissue, and by 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 kenorum from the other described species of the subgenus Nototriton : (1) having small hands and feet, with at least the distal phalanges on the fingers II, III, and IV and toes II, III, IV, and V being free of the margin of the palmar and plantar tissue; (2) tiny nostril openings, both RNW and LNH not known to exceed 0.09 mm; (3) a wide head, with HeW known to exceed 4.5 mm; (4) very narrow hands and feet, narrowest among the known members of the subgenus Nototriton within Costa Rica, HaW not known to exceed 34.1 % of HeW and FoW not known to exceed 43.2% of HeW; (5) 16S, COI, and cyt b mtDNA distances.

Description of holotype. Adult female having a total length of 73.5 mm and SL of 33.5 mm. Head slightly wider than neck and shoulders (HeW 4.4 mm, NeW 4.1 mm, ShW 4.0 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 1.1 mm, 3.3 % of SL), with nearly terminal non-protruding tiny nostrils (LNH 0.09 mm, RNW 0.09 mm) directed anterolaterally; internarial area convex in dorsal outline. Eyes relatively large (EW = 145 % of SnL), 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 weak to rounded along posterior half, indiscernible along anterior half; intercanthal area flat to slightly convex; and loreal region flat to slightly concave. No obvious cirri (nasolabial protuberances) present, but nasolabial grooves very weakly discernible on tip of snout; nasolabial grooves start at lateral margins of nares and extend ventrally at first, but take a drastic backwards curve about halfway to lip; nasolabial grooves terminate just prior to reaching margin of upper lip. Gular fold well-defined, starting on dorsolateral portion of neck, below postorbital groove, wrapping around posterolateral section of head at a slightly anterior angle and crossing venter as a smooth and weak anterior-oriented curve. Nuchal grooves weakly evident, starting above postorbital groove and converging medially at occiput. Postorbital grooves weakly defined, 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 grooves weakly discernible, but vertical mandibular groove welldefined. Horizontal mandibular groove starting at corner of mouth and extending horizontally to vertical portion of mandibular groove. Mandibular groove existing as a single solid structure, starting along inferior margins of postorbital grooves and traveling vertically to and crossing gular region, just posterior of inner mandibular grooves. Inner mandibular grooves weakly evident, principally discernible for a small section, running medially parallel to posterior portion of mandibular bones, becoming indiscernible near anterior tip of lower jaw. Pair of very weakly, but discernible, raised parotoid glands present on dorsolateral margin of head between orbits, postorbital grooves, and occiput. Snout not evidently protruding beyond anterior margin of lower lip in lateral view. No mental gland visible under skin of anterior intermandibular region.

Arms relatively long and slender overall (FLL = 4.8 mm, 14.3 % of SL), without noticeable hypertrophied forearm compared to upper arm. Hands very small and slender (HaL = 1.7 mm, 26.6 % of VGS; HaW = 1.5 mm, 34.1 % of HeW). Fingers II, III, and IV short and thick, protruding freely, with at least ultimate and all to part of penultimate phalanges being free beyond interdigital tissue margin (LF2 0.62 mm, LF3 0.53 mm); no discernible indentation at interdgital space between fingers I and II. Tips of fingers rounded, with terminal pads discernible on ventral surface. Palmar surfaces appearing to be smooth overall. Dorsal surfaces of hands with discernible interdigital grooves, especially between fingers II-III and III-IV, that start at interdigital tissue margins and cross onto metacarpal region. Relative lengths of fingers on right hand I <IV <II <III.

Legs relatively long and slender overall (HLL 5.3 mm, 15.8 % of SL), with lower leg being very slightly thicker than upper leg. Feet very small and slender (FoL 2.3 mm, 35.9 % of VGS; FoW 1.9 mm, 43.2 % of HeW). Toes II, III, IV and V protruding freely, with at least ultimate (toes II, IV, and V) and penultimate (Toe III) phalanges being free beyond interdigital tissue margin (LT2 0.78 mm, LT3 0.65 mm), Toe I with very minimal indentation at interdgitial space. Tips of toes rounded, with terminal pads discernible on ventral surfaces. Plantar surfaces appearing to be smooth overall, without any evident dermal creases. Dorsal surfaces of feet with discernible interdigital grooves, especially between toes II-III, III-IV, and IV-V, which start at interdigital tissue margins and cross onto 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 = 4.4 mm; TW = 22.8 % 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 six 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, 40.0 mm in length, cylindrical in cross section, having a weakly discernible constriction at base, and evenly tapering to pointed terminus; in life, approximately 20 caudal grooves discernible on anterior 4/5 ths of tail. Skin on surfaces of head, body, limbs, and tail smooth.

Coloration in life. The ground color of the dorsal and lateral surfaces of the head and trunk consisted of a nearly uniform fleshy-orange coloration. There were not many secondary markings on the dorsal and lateral surfaces of the head and trunk, but a small concentration of larger irregular dark brown markings were visible on the snout, nuchal region, and hips. Additionally, there were numerous very fine white chromatophores scattered thourghout the dorsal dorsal and lateral surfaces of the head and body. The iris was bright orangish-red with a dark brownishmaroon reticulation.

The upper surfaces of the arms and legs were very similar in coloration and pattern to that of the abovementioned chromatic characteristics of the dorsal and lateral surfaces of the head and body, but there appeared to be a slightly brighter orange hue on the dorsal surfaces of the limbs.

The dorsal and dorsolateral surfaces of the tail were nearly uniform fleshy-orange, but were similar to that of the limbs in having a slightly more brighter orange hue. Additionally, there were some irregular dark brown patches, one very evident patch was found about one third down (anterior towards posterior orientation) the length of the tail. As on the rest of the dorsal and lateral surfaces of the holotype, numerous very fine white chromatophores were visible scattered randomly throughout the tail.

The ventrolateral surfaces of the head, limbs, body, and tail were contrasted from the superior surfaces by consisting of a concentration of fine white or pale fleshy-orange markings on a darker brownish-gray background. The gular patch was slightly more pale in comparison to the other ventral surfaces. The palmar and plantar surfaces were pale gray, lacking discernible chromatophores, however a red reticulated pattern was discernible under the skin, formed by a network of blood-filled capillaries.

Coloration in ethanol. After more than five years in ethanol (70%), the overall coloration of the holotype has darkened throughout and contains a principal dark brown tone on the dorsal surfaces of the head and body. Two pale tannish-yellow patches are visible on the posterior dorsolateral surfaces of the head, where the parotoid glands are located. The dorsal surface of the entire tail is also a pale tannish-yellow coloration, with the exception of a darker brownish gray transversal band, located about one third down (anterior towards posterior orientation) the length of the tail. The ventral surfaces of the body and tail are darker brownish-gray. The ventral surface of the head has an evident paler tone compared to that of the rest of the body and tail.

Measurements (in mm), limb interval, and percentages of the holotype. SL 33.5; total length 73.5; tail length 40.0; ShW 4.0; HeW 4.4; NeW 4.1; EW 1.6; SnL 1.1; JSL 3.9; LGFS 7.0; LNH 0.09; RNW 0.09; IND 1.1; NLP 0.5; ICD 2.0; HLL 5.3; FLL 4.8; TW 4.4; VGS 6.4; FSL 8.6; UHL 3.6; AGL 19.3; VL 1.9; HaW 1.5; HaL 1.7; LF2 0.62; LF3 0.53; WF3 0.40; FoW 1.9; FoL 2.3; LT2 0.78; LT3 0.65; WT3 0.43. Limb interval six. Measurements in related percentages: VGS/SL 19.1 %; IND/HeW 25.0 %; AGL/SL 57.6 %; HeW/SL 13.1 %; Hew/AGL 22.8 %; SnL/ HeW 25.0 %; LNH/HeW 2.0 %; LNH/SL 0.27 %; RNW/HeW 2.0 %; RNW/SL 0.27 %; HLL/SL 15.8 %; FLL/SL 14.3 %; HaL/VGS 26.6 %; FoL/VGS 35.9 %; Haw/HeW 34.1 %; FoW/HeW 43.2 %; LT2/FoL 33.9 %; LF2/HaL 36.5 %; WT3/FoW 22.6 %; WF3/HaW 26.7 %.

Noteworthy variation. The paratopoype UCR 23688 had discernible nasolabial protruberences that extended slightly beyond the upper lip margin, where as the holotype and other two paratopotypes did not have evident nasolabial protruberences.Additionally, UCR 23688 completely lacked any discernible nostril openings, even when viewed under a disecting scope at 30x magnification. Although we did not perform any internal examination to determine the sexes of the type series specimens, we feel that it is very likely that UCR 23688 is a male and the holotype UCR 23685 and the other two paratopotypes ( UCR 23686 and UCR 23687) are females .

Measurements (in mm), limb intervals, and percentages of the paratopotypes. SL 27.5–31.3; ShW 3.2– 4.1; HeW 3.9–4.8; NeW 3.4–4.2; EW 1.3–1.5; SnL 0.9–1.2; JSL 3.3–4.1; LGFS 6.0–7.0; LNH 0.00–0.09; RNW 0.00–0.09; IND 0.9–1.1; NLP 0.4–0.7; ICD 1.7–2.1; HLL 4.8–6.0; FLL 4.3–5.0; TW 3.3–4.4; VGS 5.1–5.9; FSL 7.5–8.2; UHL 3.1–3.8; AGL 16.5–17.8; VL 1.6–1.9; HaW 1.1–1.5; HaL 1.3–1.8; LF2 0.65–0.78; LF3 0.47–0.68; WF3 0.28–0.43; FoW 1.4–1.9; FoL 1.8–2.3; LT2 0.50–0.87; LT3 0.71–0.87; WT3 0.28–0.43. Limb intervals six. Measurements in related percentages: VGS/SL 18.4–18.8 %; IND/HeW 21.4–25.6 %; AGL/SL 56.9–58.2 %; HeW/ SL 14.2–15.3 %; Hew/AGL 22.5–27.0 %; SnL/HeW 21.4–25.0 %; LNH/HeW 0.0–2.1 %; LNH/SL 0.0–0.31 %; RNW/HeW 0.0–1.9 %; RNW/SL 0.0–0.28 %; HLL/SL 17.5–19.2 %; FLL/SL 15.6–16.0 %; HaL/VGS 25.5–30.5 %; FoL/VGS 35.3–39.0 %; Haw/HeW 28.2–31.3 %; FoW/HeW 35.9–39.6 %; LT2/FoL 21.7–43.5 %; LF2/HaL 43.3–50.0 %; WT3/FoW 17.5–22.6 %; WF3/HaW 23.3–28.6 %.

Etymology. The specific epithet “ kenorum ” is a patronym, used as a noun in the plural masculine genitive case. This taxon is named in honor of Kenneth Marc Kubicki (1946–2008), the father of the senior author who was always very supportive of BK’s interests, including a life-long passion with nature (especially fishes and amphibians) and natural history. Additionally, this taxon is named for Kenneth Marc Kubicki-Reyes (2009–), the son of BK and AR; to symbolize our hope and optimism with the continued study, protection, and appreciation of our world’s natural resources, which are soon going to fall into the hands of our children and their future generations.

Habitat and natural history observations. Nototriton kenorum has been found exclusively within moss growing on the trunks and branches of trees. More than twenty different individuals of N. kenorum have been observed by the senior author in the wild, and all were found within moss in arboreal situations. Likely N. kenorum can also inhabit moss and other microhabitats that offer similar physical parameters, growing on rocks and terrestrial surfaces, but until now none have been discovered to inhabit such sites.

Distribution. Nototriton kenorum is endemic to Costa Rica, and currently only known to inhabit a very small section of unusually low elevation cloud forest habitat within the lower portion of the Tropical Premontane Rainforest life zone ( Holdridge 1967) along the northern slopes of the Turrialba Volcano. The known altitudinal range for N. kenorum is from ca. 775–900 masl. This is the only species of Costa Rican moss salamander that is thus far known to exclusively inhabit elevations below 1000 masl.

Figures

FIGURE 11. Holotype of Nototriton kenorum sp. nov. in life on white background. Photograph by BK.

FIGURE 12. Dorsal, lateral, and ventral views of the body of the holotype of Nototriton kenorum sp. nov. in preservation. Photograph by BK.

FIGURE 13. Dorsal views of the hand and foot and detail of the face of the holotype of Nototriton kenorum sp. nov. in preservation. Photograph by BK.