Nototriton maximo, 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 : 485-487

Nototriton maximo sp. nov.

Maximo’s moss salamander

Holotype. UCR 23689 ( Fig. 17 ), an adult female from Costa Rica: Provincia de Guanacaste : Cantón de Tiláran: Distrito de Tronadora: edge of road approximately 3 kilometers NNW of the entrance to the Santa Elena Reserve, Monteverde , ca. 1425 m a.s.l., collected by Brian Kubicki in the company of Aura Reyes on 22 February 2013.

Paratopotype. UCR 23690, same collection data as the holotype .

Paratypes. UCR 23691 Provincia de Guanacaste: Cantón de Tiláran : Distrito de Tronadora : edge of road approximately 200 meters NNE of the entrance of the Santa Elena Reserve, Monteverde, ca. 1600 m a.s.l., collected by Brian Kubicki in the company of Aura Reyes on 26 April 2013 . UCR 23692 same locality data as UCR 23691, but collected by Brian Kubicki in the company of Aura Reyes on 5 July 2016 . UCR 23693, a subadult from Costa Rica: Provincia de Alajuela: Cantón de Upala: Distrito de Aguas Claras: moss on tree trunk about 3 meters above the ground, northeastern slope of the Rincon de la Vieja Volcano , Rincon de la Vieja National Park , ca. 1450 m a.s.l., collected by Brian Kubicki in the company of Aura Reyes on 17 December 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 maximo 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 maximo 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 toes II, III, IV, and V being free of the margin of the palmar and plantar tissue; (2) typically shorter front and hind limbs, HLL known to range from 4.1–5.2 mm and FLL known to range from 4.0– 4.8 mm; (3) 16S, COI, and cyt b mtDNA distances.

Description of holotype. Adult female having a total length of 71.8 mm and SL of 31.9 mm. Head slightly wider than neck and shoulders (HeW 4.0 mm, NeW 3.7 mm, ShW 3.7 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 to truncate in profile; snout relatively short (SnL 1.2 mm, 3.8 % of SL), with nearly terminal non-protruding small nostrils (LNH 0.12 mm, RNW 0.12 mm) directed anterolaterally; internarial area convex in dorsal outline. Eyes relatively large (EW = 133 % of SnL), protruding well beyond dorsal and ventral outline of head, directed anterolaterally, with a distinct suborbital groove. Top of head flat and smooth, tapering toward anterior terminus, lacking contrasting interorbital or other dermal structures. Canthus rostralis distinct; intercanthal area flat to slightly convex; and loreal region flat to slightly concave. No obvious cirri (nasolabial protuberances) present. Nasolabial grooves discernible on tip of snout, starting at lateral margins of nares and extending nearly vertically (with a slight outward angle) to a point just above upper lip margin. Gular fold well-defined, starting on dorsolateral portion of neck, below weakly discernible postorbital groove, wrapping around posteriolateral section of head at a slightly anterior angle and crossing venter as a smooth and weak anterior-oriented curve. Nuchal grooves very weak to indiscernible. Postorbital grooves very weak, nearly indiscernible, 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 nearly indiscernible, starting at corners of mouth and extending horizontally to vertical mandibular groove. Vertical mandibular grooves discernible, but weak starting along inferior margins of postorbital grooves and extending vertically to gular region, terminating at junction with inner mandibular grooves. Inner mandibular grooves evident, running medially parallel to mandibular bones, becoming indiscernible near anterior tip of lower jaw. Pair of nearly indiscernible and weakly raised parotoid glands present on dorsolateral margin of head among 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, 15.0 % of SL), without noticeable hypertrophied forearm compared to upper arm. Hands very small and slender (HaL = 1.7 mm, 32.1 % of VGS; HaW = 1.6 mm, 40.0 % of HeW). Fingers II, III, and IV long and slender, protruding freely, with at least ultimate and penultimate phalanges being free beyond interdigital tissue margin (LF2 0.71 mm, LF3 0.71 mm); a weak, but evident indentation at interdgitial space between fingers I and II. Tips of fingers rounded, with terminal pads discernible on ventral surfaces, especially fingers II and III. Palmar surfaces appearing to be smooth overall. Dorsal surfaces of hands with discernible interdigital grooves 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 5.2 mm, 16.3 % of SL), with lower leg being very slightly thicker than upper leg. Feet very small and slender (FoL 2.1 mm, 39.6 % of VGS; FoW 2.0 mm, 52.5 % of HeW). Toes II, III, IV and V protruding freely, with at least ultimate (Toe V) and penultimate (toes II, III, and IV) phalanges being free beyond interdigital tissue margin (LT2 0.79 mm, LT3 0.68 mm); very minimal to indiscernible indentation at interdgitial space between toes I and II. 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 that 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, 39.9 mm in length, cylindrical in cross section, having a very slight constriction at base, and evenly tapering to pointed terminus; in life, no caudal grooves were discernible. 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 reddish-orange. There were several pale fleshy colored dash-like markings on the lateral and dorsolateral surface of the body.Additionally, there were some scattered dark brown to black small irregular markings and tiny white spots on the dorsal and lateral surfaces of the head and body. The iris was dark reddish-orange with dark brownish-black reticulation.

The upper surfaces of the arms and legs were very similar in overall coloration and pattern to that of the abovementioned chromatic characteristics of the dorsal and lateral surfaces of the head and body.

The dorsal and dorsolateral surfaces of the tail were uniform bright reddish-orange.

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 brown to brownish-orange background. The area directly surrounding the cloaca had a concentration of bright orange chromatophores.

Coloration in ethanol. After more than eight years in ethanol (70%), the overall ground coloration of the holotype has shifted to a pale fleshy tan dorsally. Throughtout the dorsal and dorsolateral surfaces of the head and body there are also numerous fine to medium-sized darker markings and spots; on the dorsolateral section of each side of the trunk, there are a series of darker dash-like markings. The ventral surfaces of the head, body, limbs, and tail are darker brownish-gray with very small pale patches scattered throughout.

Measurements (in mm), limb interval, and percentages of the holotype. SL 31.9; total length 71.8; tail length 39.9; ShW 3.7; HeW 4.0; NeW 3.7; EW 1.6; SnL 1.2; JSL 3.7; LGFS 6.4; LNH 0.12; RNW 0.12; IND 1.0; NLP 0.5; ICD 1.8; HLL 5.2; FLL 4.8; TW 4.4; VGS 5.3; FSL 8.0; UHL 3.6; AGL 19.3; VL 1.9; HaW 1.6; HaL 1.7; LF2 0.71; LF3 0.71; WF3 0.34; FoW 2.0; FoL 2.1; LT2 0.79; LT3 0.68; WT3 0.37. Limb interval six. Measurements in related percentages: VGS/SL 16.6 %; IND/HeW 25.0 %; AGL/SL 60.5 %; HeW/SL 12.5 %; Hew/AGL 20.7 %; SnL/ HeW 30.0 %; LNH/HeW 3.0 %; LNH/SL 0.38 %; RNW/HeW 3.0 %; RNW/SL 0.38 %; HLL/SL 16.3 %; FLL/SL 15.0 %; HaL/VGS 32.1 %; FoL/VGS 39.6 %; Haw/HeW 40.0 %; FoW/HeW 52.5 %; LT2/FoL 37.6 %; LF2/HaL 41.8 %; WT3/FoW 18.5 %; WF3/HaW 21.3 %.

Noteworthy variation. The paratype ( UCR 23693) has discernible differences in the overall structure of the hands and feet, which are especially evident while comparing the digits to those of other members of the type series. The digits on the hands and feet of UCR 23693 are shorter and more tapered distally than on the other type series specimens; this could be related to ontogenesis, given the smaller size (22.0 mm) of UCR 23693 , but UCR 23690 , with a SL of 22.5 mm, has clearly visible differences in the structure of the digits from UCR 23693 . The overall digit structure of UCR 23690 is similar to that of UCR 23689, UCR 23691 , and UCR 23692 .

Measurements (in mm), limb intervals, and percentages of the paratopotypes. SL 22.0–28.5; ShW 2.6– 3.4; HeW 3.1–4.0; NeW 2.9–3.5; EW 1.1–1.3; SnL 0.8–1.1; JSL 2.7–3.4; LGFS 4.8–5.7; LNH 0.15–0.25; RNW 0.09–0.19; IND 0.7–1.0; NLP 0.3–0.6; ICD 1.6–1.8; HLL 4.1–5.2; FLL 4.0–4.5; TW 2.8–3.9; VGS 4.0–5.2; FSL 6.2–7.5; UHL 2.5–3.4; AGL 12.5–16.9; VL 0.9–1.4; HaW 1.0–1.4; HaL 1.0–1.5; LF2 0.47–0.68; LF3 0.43–0.68; WF3 0.22–0.31; FoW 1.3–1.7; FoL 1.4–2.0; LT2 0.53–0.76; LT3 0.4–0.71; WT3 0.25–0.34. Limb interval five–six. Measurements in related percentages: VGS/SL 18.2–19.1 %; IND/HeW 20.0–25.0 %; AGL/SL 56.8–59.3 %; HeW/ SL 13.4–14.2 %; Hew/AGL 23.3–24.8 %; SnL/HeW 25.8–28.6 %; LNH/HeW 4.0–7.8 %; LNH/SL 0.56–1.11 %; RNW/HeW 2.6–5.0 %; RNW/SL 0.34–.0.71 %; HLL/SL 16.8–19.5 %; FLL/SL 15.8–18.2 %; HaL/VGS 25.0–30.2 %; FoL/VGS 34.9–39.6 %; Haw/HeW 31.3–35.5 %; FoW/HeW 40.6–42.9 %; LT2/FoL 37.9–42.7 %; LF2/HaL 41.3–47.0 %; WT3/FoW 19.2–21.5 %; WF3/HaW 20.0–28.0 %.

Etymology. The specific epithet “ maximo ” is a patronym, used as a noun apposition. This taxon is named in honor of Maximiliano “Maximo” Flores (1964–2016), who was a good friend and neighbor of BK and AR. Maximo’s friendship and help with the efforts of the Costa Rican Amphibian Research Center and at the Guayacán Rainforest Reserve, another private property owned by BK, will always be very much appreciated. Maximo was always very willing to join BK during both diurnal and nocturnal field outings, and he accompanied BK and AR on numerous trips throughout the cloud forest regions of Costa Rica searching for moss salamanders.

Habitat and natural history observations. Nototriton maximo has been found within moss growing on the ground, fallen and standing tree trunks and accessable branches of trees.

Distribution. Nototriton maximo is endemic to Costa Rica, and currently only known to inhabit two very small distinct cloud forest regions in northwestern Costa Rica. The first region is along the continental divide just north and northwest of the Monteverde Cloud Forest Reserve. The second region is along the northern slopes of the Rincón de la Vieja Volcano. The known altitudinal range for N. maximo is from ca. 1425–1600 masl.

Figures

FIGURE 17. Holotype of Nototriton maximo sp. nov. in life on white background. Photograph by BK.