Nototriton nelsoni, Townsend, Josiah H., 2016

Townsend, Josiah H., 2016, Taxonomic revision of the moss salamander Nototriton barbouri (Schmidt) (Caudata: Plethodontidae), with description of two new species from the Cordillera Nombre de Dios, Honduras, Zootaxa 4196 (4), pp. 511-528 : 520-523

Nototriton nelsoni sp. nov.

Texíguat Moss Salamander Figure 5

Nototriton barbouri: McCranie et al. (1993: 387) .

Nototriton sp. (in part): Townsend et al. (2010: 3).

Nototriton sp. B.: Townsend et al. (2011a: 277), Rafaëlli (2013: 368), Townsend et al. (2013: 360). Nototriton sp.: Townsend et al. (2012: 96).

Nototriton (Bryotriton) barbouri (in part): Dubois & Raffaëlli (2012: 141), Rafaëlli (2013: 368).

Holotype. USNM 578300 ( Fig. 5 ), an adult male from Cerro El Chino (15.525394°N, 87.278672°W), 1,420 m elevation, above La Liberación, Refugio de Vida Silvestre Texiguat, Departamento de Atlántida, Honduras; collected 19 June 2010 by B.K. Atkinson, C.A. Cerrato-Mendoza, J.H. Townsend, and L.D. Wilson; original field number JHT 3159. GenBank accession numbers JN377387 (16S) , JN377391 (cyt b), JN377403 (COI).

Paratypes. Four, all from about 2.5 km (airline) NNE of La Fortuna (15.44°N, 87.31°W), Refugio de Vida Silvestre Texiguat, Departamento de Yoro; one male, USNM 339710, 1,690 m elevation; and two females, USNM 339709, 1,690 m elevation, and USNM 339711, 1,800 m elevation; and one cleared-and-stained specimen, USNM 509333, 1,600 m elevation, GenBank accession number AF199138 (cyt b).

Diagnosis. A member of the genus Nototriton diagnosed by possessing 13 costal grooves (>16 costal grooves in Oedipina ), the presence of a sublingual fold and hands and feet longer than broad (sublingual fold absent and hands and feet broader than long in Bolitoglossa ), and small nares (0.006–0.010 NL/SL; 0.017–0.029 NL/SL in Cryptotriton and Dendrotriton ). Phylogenetic analysis supports inclusion of N. nelsoni in the subgenus Bryotriton, belonging to the northern clade with N. brodiei , N. oreadorum , and N. stuarti ( Fig. 1 ). From the other members of the northern clade, N. nelsoni can be distinguished from N. brodiei by having a relatively broader head (HW/SVL 0.127–0.142, versus 0.120 in N. brodiei ), relatively longer limbs (FLL/SVL 0.173–0.198 and HLL/SVL 0.203– 0.223, versus 0.148–0.151 and 0.166–0.180 in N. brodiei ), and by having fewer maxillary teeth (38–53, versus 60– 62 in N. brodiei ); from N. oreadorum by having a relatively longer and broader head (HL/SVL 0.185–0.226 and HW/SVL 0.127–0.142, versus 0.178–0.182 and 0.117–0.122 in N. oreadorum ) and relatively longer front limbs (FLL/SVL 0.173–0.198, versus 0.158–0.178 in N. oreadorum ); and from N. stuarti in having relatively longer hind limbs (HLL/SVL 0.203–0.223, versus 0.178 in N. stuarti ) and a greater number of maxillary teeth (38–53, versus 36 in N. stuarti ).

From the other constituent species of Bryotriton, N. nelsoni can be differentiated from N. barbouri by having a relatively longer tail (TL/SVL 1.144–1.532, versus 0.802–1.165 in N. barbouri ) and a lower average number of costal grooves between adpressed limbs (4.9 [± 1.4], versus 6.2 [±0.9] in N. barbouri ); from N. lignicola in having relatively broader hind feet (HFW/SVL 0.044–0.058, versus 0.035–0.046 in N. lignicola ) and a lower average number of costal grooves between adpressed limbs (4.9 [± 1.4], versus 5.9 [±0.5] in N. barbouri ); from N. limnospectator in having a relatively broader head (HW/SVL 0.127–0.142, versus 0.111–0.118 in N. limnospectator ); from N. mime in having a relatively longer tail (TL/SVL 1.144–1.532, versus 0.698–1.117 in N. mime ) and relatively shorter limbs (FLL/SVL 0.173–0.198 and HLL/SVL 0.203–0.223, versus 0.195–0.246 and 0.224–0.254 in N. mime ); from N. picucha in having broader hind feet (HFW/SVL 0.044–0.058, versus 0.042– 0.043 in N. picucha ) and a higher average number of costal grooves between adpressed limbs (4.9 [± 1.4], versus 4.0 [±0.7] in N. picucha ); and from N. tomamorum in having feet with well-developed digits (syndactylous feet in N. tomamorum ), a greater number of maxillary and vomerine teeth (38–53 maxillary teeth and 17–24 vomerine teeth, versus 26 maxillary teeth and 11 vomerine teeth in N. tomamorum ) and smaller nares (NL/SL 0.006–0.010, versus 0.018 in N. tomamorum ). Nototriton nelsoni can be distinguished from N. saslaya , the only species of the subgenus Nototriton that occurs in the Chortís Highlands, by having more maxillary and vomerine teeth (38–53 maxillary teeth and 17–24 vomerine teeth, versus 17–22 maxillary teeth and 3–11 vomerine teeth in N. saslaya ).

Each of the species of Bryotriton in the northern clade are allopatric with respect to each other, and N. nelsoni can be further distinguished from these species based on model-corrected genetic distances ( Table 2 ), being 2.1% (16S) and 9% (cyt b) divergent from its closest relative, N. stuarti , and 2.3% (16S) and 5.4–5.7% (cyt b) divergent from samples from PN Pico Bonito, the geographically closest population, itself described as a new species below.

Description of holotype. An adult male (SVL = 31.9 mm, total length = 68.4 mm) with a slender body and reduced limbs. The head is rounded, slightly broader than the body; nostrils are relatively small (NL/SVL=0.006), and the snout is acutely rounded and of moderate length. Nasolabial grooves are visible but slight, with nasolabial protuberances apparent. The eyes are relatively large and protuberant. The mental gland is not apparent. There are 53 maxillary teeth, 4 slightly enlarged premaxillary teeth in line with the maxillary teeth, and 24 vomerine teeth in two well-defined arches. The limbs are short (CLL/SVL=0.42), with approximately 3.5 costal grooves between the adpressed limbs. The hands and feet are narrow with well-developed digits bearing subdigital pads. The relative length of the digits is I<IV<II<III on the hands and I<V<II<IV<III on the feet, and the tail is longer than the body (TL/SVL=1.114).

Measurements of holotype (in mm). SVL 31.9; AG 19.1; TW 3.8; HL 6.9; HW 4.2; TL 41.0; HLL 7.2; FLL 6.4; CLL 13.6; FFW 1.1; HFW 1.5; NL 0.2; eyelid length 1.8; eye width 0.9; interorbital distance 1.6; anterior rim of orbit to snout 1.5; distance separating internal margins of nares 1.4; distance separating external margins of nares 1.8.

Color in life of holotype. Description of the coloration of the holotype based on a series of color photographs taken in life (color names and numbers follow Köhler [2012]): dorsal surfaces of paratoid region of head, body, and tail darkly mottled, with dominant ground color being Dark Carmine (61); lateral surfaces more heavily mottled with Brick Red (36), becoming nearly solid Ferruginous (35) near the edge of the ventral coloration, with Sepia (286) spots beginning on the centrolateral portion of costal groove 3 and becoming larger posteriorly, with one large blotch present centrolaterally from costal groove 12 to the hind limb; series of irregular Salmon Color (251) middorsal botches corresponding with the relative position of each vertebra, forming the center of a faint herringbone dorsal pattern; dorsal surfaces of head and dorsal and lateral surfaces of body covered with small, irregular Smoky White (261) and Pearl Gray (262) spots; dorsal surface of head mottled Sepia (286), Dark Carmine (61), and Carmine (64), with Smoky White (261) and Pearl Gray (262) spotting, becoming more profuse on lateral surfaces of head; series of Pearl Gray (262) spotting lining the margin of the upper lip; dorsal surface of limbs Sepia (286) with Dark Carmine (61), Deep Vinaceous (248), and Light Pratt’s Rufous (71) stippling, becoming more profuse towards body; ventral surface of head and body Fuscous (283), with Smoky White (261) and Pearl Gray (262) spots slighting larger than those seen laterally; dorsal and lateral surfaces of tail Dark Carmine (61), with Smoky White (261) and Light Lavender (201) spotting more profuse laterally; ventral ground color of tail Dusky Brown (285), being somewhat darker than body, with scattered Smoky White (261) and Light Lavender (201) spotting; color of iris Peach Red Ruby (70).

Osteology. Based on examination of digital radiographs for the holotype ( Fig. 6 A), Nototriton nelsoni is a typical member of the genus possessing a single cervical vertebra, 14 trunk vertebrae (13 of which bear ribs), and 2 caudosacral vertebrae; a completely fused skull roof formed through contact of the parietal bones; frontal processes of premaxilla fused at point of origin and separate immediately dorsoposterior to origin; preorbital vomerine processes well-developed into a pair of elongate arches each bearing a single row of numerous teeth, extending beyond the outer margins of the choanae; columella absent; phalangeal formulae 1-2-3-2 and 1-2-3-3-2; penultimate phalanges reduced, exceeded in length by terminal phalanges on digits II, III, and IV of the forelimbs and digits II, III, IV, and V of hind limbs; terminal phalanges slightly expanded at distal tips, expansion more pronounced in digit III of forelimbs and digit III of the hindlimbs; mesopodial elements not mineralized. Examination of radiographs of the three paratypes (USNM 339709–11) generally agreed with those of the holotype; with one paratype (USNM 339710) demonstrating incomplete fusion of the skull with sutures apparent between the frontal and parietal elements, and a small frontoparietal fontanelle.

Etymology. The specific epithet is a patronym honoring Dr. Cyril “Cirilo” Hardy Nelson-Sutherland, Professor Emeritus and co-founder of the Department of Biology at the Universidad Nacional Autónoma de Honduras, and co-founder and former director and curator of the university herbarium, which was renamed in his honor in 2011. Dr. Nelson devoted his career to studying the flora of Honduras and providing instruction and guidance to generations of Honduran biology students, a career which culminated with the publication of the 1,576-page magnum opus, the Catálogo de las Plantas Vasculares de Honduras, Espermatofitas (Nelson- Sutherland 2008).

Geographic and ecological distribution. Nototriton nelsoni is known only from highland forest within Refugio de Vida Silvestre Texíguat, 1,420–1,800 m ( Fig. 3 ). Known localities fall entirely within the Lower Montane Wet Forest formation ( Holdridge 1967), with the habitat at the type locality being Broadleaf Cloud Forest and the locality for the paratypes being Mixed Cloud Forest transitioning to Broadleaf Cloud Forest ( Townsend 2014).

Natural history. The holotype was collected as it crawled out of an arboreal bromeliad approximately 1.5 m above the ground on a rainy night. The collection site was at the top of a small peak at the northern terminus of a ridgeline leading to the highest portion of RVS Texíguat, and the overstory was somewhat stunted with a palmdominated understory and a dense covering of epiphytic plants. This species has also been found utilizing rotten logs as daytime refugia, in sympatry with the worm salamander Oedipina gephyra ( McCranie et al. 1993: 387) . The congener N. tomamorum is known from a single specimen collected near a stream just below the locality where the four paratypes of N. nelsoni were collected.

Remarks. A photograph of the holotype of Nototriton nelsoni appeared in Townsend et al. (2012: 98) as “ Nototriton sp.”.

Figures

FIGURE 1. Bayesian phylogram of the genus Nototriton showing phylogenetic relationships based on analysis of a concatenated and partitioned dataset of fragments of the mitochondrial genes 16 S, cyt b, and COI, with Bayesian posterior probabilities and bootstrap support values from a complimentary maximum likelihood analysis shown above supported branches.

FIGURE 3. Distribution of Nototriton in north-central Honduras; red diamond = Montaña Macuzal, type locality of N. barbouri; black diamond = N. barbouri (PN Pico Pijol); circles = N. nelsoni, RVS Texíguat (red = type locality); squares = N. oreadorum, PN Pico Bonito (red = type locality); crosses = N. lignicola; triangle = N. mime; inverted triangle = N. picucha.

FIGURE 5. Two aspects of the adult male holotype of Nototriton nelsoni (USNM 578300), from above La Liberación, 1,420 m elevation, Refugio de Vida Silvestre Texiguat, Departamento de Atlántida, Honduras.

FIGURE 6. Digital radiographs of the holotypes of Nototriton nelsoni (A; USNM 578300) and N. oreadorum (B; USNM 497552).