Distribution, encounter rate and conservation status of Aquiloeurycea cafetalera (Caudata: Plethodontidae), a recently described Mexican salamander

The knowledge of the natural history of a species, its population traits and spatial distribution are essential to evaluate its risk of extinction and proposing strategies for its conservation. For poorly studied species inhabiting regions with a high degree of habitat conversion by anthropogenic activities, it is even more urgent to obtain this information. In this study, we carried out fieldwork and database analyses to obtain information on the ecology, natural history and spatial distribution of the plethodontid salamander Aquiloeurycea cafetalera, and we evaluated its conservation status according to the IUCN and the Mexican environmental agency (SEMARNAT). We found 109 individuals in 20 of the 43 localities visited (sampling effort = 1,174 person-hours). The salamander counts ranged from one to 21 individuals per locality and the average encounter rate was 21 salamanders per 100 person-hours of surveying, within a range from 2 to 117 salamanders. The current potential distribution calculated is about 2,000 km2 and fragmented, which means less than half of its original potential distribution. Our results suggest that it is necessary to include this species in biodiversity conservation programs because only a very small portion of its spatial distribution falls within natural protected areas.O conhecimento da história natural de uma espécie, suas características populacionais e sua distribuição espacial são essenciais para avaliar seu risco de extinção e para propor estratégias para sua conservação. Para as espécies mal estudadas e que habitam regiões com um alto grau de conversão de habitat por atividades antropogênicas, é ainda mais urgente obter essas informações. Neste estudo, nós compilamos informação de banco de dados juntamente com trabalho de campo para obter informações sobre a ecologia, história natural e distribuição espacial da salamandra Aquiloeurycea cafetalera, e também avaliamos seu estado de conservação de acordo com a IUCN e a Agência Ambiental Mexicana (SEMARNAT). Encontramos 109 indivíduos em 20 das 43 localidades visitadas (esforço de amostragem = 1174 horas.pessoa). A contagem de salamandras variou de um a 21 indivíduos por localidade, e a taxa média de encontro foi de 21 salamandras por 100 horas.pessoa de levantamento, num intervalo de 2 a 117 salamandras. A atual distribuição potencial calculada é de cerca de 2000 km2 e é fragmentada, o que significa menos da metade da sua distribuição potencial original. Nossos resultados sugerem que é necessário incluir essa espécie em programas de conservação da biodiversidade, visto que somente uma pequena porção de sua distribuição espacial está incluída em áreas naturais protegidas

In Search of Critically Endangered Species: The Current Situation of Two Tiny Salamander Species in the Neotropical Mountains of Mexico

Worldwide, one in every three species of amphibian is endangered, 39 species have gone extinct in the last 500 years and another 130 species are suspected to have gone extinct in recent decades. Of the amphibians, salamanders have the highest portion of their species in one of the risk categories, even higher than the frogs. To date there have been few studies that have used recent field data to examine the status of populations of endangered salamanders. In this study we evaluate the current situation of two tiny salamanders, Parvimolge townsendi and Thorius pennatulus, both of which are distributed at intermediate elevations in the mountains of the northern Neotropics and are considered to be critically endangered; the first has been proposed as possibly extinct. By carrying out exhaustive surveys in both historical and potentially suitable sites for these two species, we evaluated their abundance and the characteristics of their habitats, and we estimated their potential geographic distribution. We visited 22 sites, investing 672 person-hours of sampling effort in the surveys, and found 201 P. townsendi salamanders in 11 sites and only 13 T. pennatulus salamanders in 5 sites. Both species were preferentially found in cloud forest fragments that were well conserved or only moderately transformed, and some of the salamanders were found in shade coffee plantations. The potential distribution area of both species is markedly fragmented and we estimate that it has decreased by more than 48%. The results of this study highlight the importance of carrying out exhaustive, systematic field surveys to obtain accurate information about the current situation of critically endangered species, and help us better understand the crisis that amphibians are facing worldwide

Isthmura corrugata Sandoval-Comte & Pineda & Rovito & Luría-Manzano 2017, sp. nov.

<i>Isthmura corrugata</i> sp. nov. <p>Suggested English name: Corrugated Salamander. Suggested Spanish name: Salamandra corrugada. (Figures 2, 3)</p> <p> <b>Holotype.</b> CARIE 0 943 (Colección de Anfibios y Reptiles del Instituto de Ecología, A.C.), an adult male collected 9 km NW of Coatepec, Veracruz, México (19° 29´N, 97° 02´W), 2,106 m elevation, collected by A. Sandoval- Comte (original field number ASC 200) at 22:15 h on 28 April 2014 (Fig. 2 A–2F).</p> <p> <b>Paratype.</b> CARIE 0 960, an adult male, same locality data as the holotype, collected by R. Luría-Manzano at 15:18 h on 4 August 2014 (Fig. 2 G–2H).</p> <p> <b>Diagnosis.</b> This is a plethodontid salamander of the genus <i>Isthmura</i>, based on its large size, robust body, and presence of a sublingual fold as well as on mtDNA sequence data. Differs from all other bolitoglossines except <i>Pseudoeurycea papenfussi</i> by its extremely well-defined and bulging costal folds, giving it a segmented appearance that extends even across the venter. Distinguished from all species of <i>Aquiloeurycea</i> by its larger size (<i>A. scandens</i> maximum SL 71 mm) and from similarly sized species of <i>Bolitoglossa</i> by the presence of a sublingual fold. Differs from large, robust species of <i>Pseudoeurycea</i> such as <i>P. papenfussi</i> and <i>P. smithi</i> by having more substantial foot webbing and triangularly shaped toes. It is the second smallest species of <i>Isthmura</i> (maximum SL 85.3 mm), only slightly larger than <i>I. naucampatepetl</i> (maximum SL 82.9 mm); all other species in the genus are substantially larger (maximum SL in: <i>I. sierraoccidentalis</i> 88.3 mm; <i>I. maxima</i> 128.1 mm; <i>I. bellii</i> 146 mm; <i>I. boneti</i> 107 mm; <i>I. gigantea</i> 161 mm; Parra-Olea <i>et al.</i> 2005; Raffaëlli 2007). No females of <i>I. corrugata</i> have been found, so the maximum size of this species is likely greater than 85.3 mm SL because female <i>Isthmura</i> tend to be larger than males.</p> <p> Members of the genus <i>Isthmura</i> have been characterized by the presence of spots or marks on a solid black dorsal background. The new species, however, is easily distinguished from all other members of the genus by the absence of any spot or mark on the dorsum, which instead is uniformly black, except by dull reddish brown coloration on eyelids. All other species have a series of chevrons (<i>I. boneti</i> and <i>I. gigantea</i>), half-chevrons (<i>I. bellii</i> and <i>I. maxima</i>), or small marks (<i>I. naucampatepetl</i>) along the dorsum, that are red-orange in all species except in <i>I. naucampatepetl</i>, in which they are pink (Parra-Olea <i>et al.</i> 2001; Parra-Olea <i>et al.</i> 2005). <i>Isthmura sierraoccidentalis</i> has a predominantly black dorsum, but all known individuals have some degree of reduced redorange dorsal spotting (Lowe <i>et al.</i> 1968; Rovito <i>et al.</i> 2015). <i>Isthmura corrugata</i> is further distinguished by contrasting coloration between the blackish brown dorsal and vinaceous brown ventral background color, whereas all other species of the genus have a uniformly black dorsal and ventral background coloration. In addition, this species has a body marked by deep grooves and an unusual coloring above the eyes (dull reddish brown). Some body proportions also distinguish the new species from its congeners (Fig. 2). It has a relatively larger head (mean HL/SL= 0.23 versus 0.15–0.18 in the other species) and a relatively shorter tail (mean TL/SL= 0.69 versus 0.77– 0.98 in the other species).</p> <p> <b>Description of holotype.</b> Among the large salamanders of the genus <i>Isthmura</i>, this is a robust but relatively small species (maximum SL= 85.3 mm). Its body has a very muscular appearance. It has a prominent, broad (HW/ SL= 0.22) and large head (HL/SL= 0.23) with very substantial jaw musculature. Deep postorbital groove extends from eye to end of jaw and continues to gular region. Snout is rounded and neck region is defined by deep groove behind head, slightly narrower than head. Parotoid glands are well developed and a large oval mental gland (mental gland width/HW= 0.39) was present in both specimens. Eyes are protuberant. Maxillary teeth 62 (31/31), premaxillary teeth 6, enlarged compared to maxillary teeth; vomerine teeth 46, arranged in two arcs (22/24) extending beyond outer margin of choanae; around 52 parasphenoid teeth arranged in two series as inverted “V” shape; nasolabial protuberances are poorly developed (Fig. 3). Extremely well-marked costal grooves 13, counting one each in axilla and groin (Fig. 2). Tail is relatively short (TL/SL= 0.69) and robust with basal constriction and tip rounded. Limbs are robust and relatively long (combined limb length/SL= 0.5). Digits are well defined, relatively short, stout and triangular. Digits in order of decreasing length III-II-IV-I on hands and III-IV-II-V-I on feet (Fig. 2 D). Phalangeal formulae 1-2-3-2 for hands and 1-2-3-3-2 for feet.</p> <p> <b>Coloration in life.</b> Dorsum uniformly dark, color Vandyke Brown (282) from tail to head (including hands and feet). Prominent eyelids, jaw margins and gular surface pale Cinnamon-Rufous (31). Iris Raw Umber (280). Distal half of flanks dark, like dorsal coloration; proximal half Deep Vinaceous (248) extending to the venter and ventral side of limbs (Fig. 2 A–2F).</p> <p> <b>Coloration in alcohol.</b> Coloration very similar to that in life. Dorsum, dorsal surface of head, trunk, limbs, and tail Dusty Brown (285). Eyelids Raw Umber (280), slightly darker than in live individuals. Jaw margins and gular region Dark Grayish Olive (245). Distal half of flanks same color as dorsum, proximal half Deep Vinaceous (248), extending onto ventral surface. Ventral side of the tail color slightly more grayish than rest of its dorsum. Underside of hands and feet paler than in life (Fig. 2 G–2H).</p> <p> <b>Measurements of holotype / paratype (in mm).</b> Standard length (SL: distance from snout to posterior end of vent) 71.9/85.3; head width (HW) 15.8/17.7; head length (HL: snout to gular fold) 16.3/20.8; head depth at angle of jaw 6.8/7.9; eyelid length 5.3/6.2; eyelid width 2.9/3.5; anterior rim of orbit to snout 3.6/4.5; eye diameter 2.8/ 3.3; interorbital distance 4.5/5.0; snout to forelimb 21.2/27.4; internarial distance 4.5/5.5; intercanthal distance 4.8/ 5.6; nostril diameter 0.4/0.6; snout projection beyond mandible 1.5/1.5; snout to anterior angle of vent 65.9/82.1; axilla to groin 31.6/35.1; tail length (TL) 48.3/60.2; tail width at base 7.0/7.5; tail depth at base 8.9/9.8; forelimb length 16.2/20.0; hind limb length 20.0/25.7; hand width 5.9/6.5; foot width 7.5/8.7; length of the longest (third) toe 2.1/2.3; length of fifth toe 0.9/1.2; mental gland width 6.1/6.2; mental gland length 3.8/3.8; Numbers of teeth: premaxillary 6/10; maxillary 62/60; vomerine 46/42 (Fig. 3).</p> <p> <b>Distribution and Ecology.</b> <i>Isthmura corrugata</i> is known only from the type locality, near the city of Coatepec in the mountainous region of central Veracruz (Fig. 4). This mountain range lies within the eastern portion of the Trans-Mexican Volcanic Belt. The vegetation at the type locality is cloud forest, characterized by the presence of tall trees that provide a high percentage of canopy cover, a deep layer of leaf litter (= 8cm), and a high density of bromeliads and epiphytes. The dominant tree species are <i>Clethra mexicana</i>, <i>Hedyosmum mexicanum, Miconia</i> spp, <i>Platanus mexicana</i>, <i>Quercus</i> spp, as well as tree fern species (García-Franco <i>et al.</i> 2008; Toledo-Garibaldi & Williams-Linera 2014). A frequent fog maintains high levels of humidity. The holotype was found active on the forest floor at night, whereas the paratype was encountered inactive under a layer of leaf litter (= 10 cm) during the day. Despite of <i>I. corrugata</i> has been found only in one locality, it is possible that this species may inhabit additional localities around Cofre de Perote extending to the Sierra Norte de Puebla near Cuetzalan, because a high proportion of the amphibian fauna is shared between these areas.</p> <p> Six species of salamanders have been found in sympatry with <i>Isthmura corrugata</i>: <i>Aquiloeurycea cafetalera</i>, <i>Parvimolge townsendi</i>, <i>Thorius pennatulus, Pseudoeurycea lynchi, Chiropterotriton chiropterus</i> and <i>Chiropterotriton</i> sp. Most of these species are found in the leaf litter, except for the last three, which also use arboreal bromeliads.</p> <p> <b>Etymology.</b> The specific epithet makes reference to the extremely pronounced grooves along the body, giving these salamanders a corrugated appearance.</p>Published as part of <i>Sandoval-Comte, Adriana, Pineda, Eduardo, Rovito, Sean M. & Luría-Manzano, Ricardo, 2017, A new species of Isthmura (Caudata: Plethodontidae) from the montane cloud forest of central Veracruz, Mexico, pp. 573-582 in Zootaxa 4277 (4)</i> on pages 575-579, DOI: 10.11646/zootaxa.4277.4.7, <a href="http://zenodo.org/record/814669">http://zenodo.org/record/814669</a&gt

FIGURE 2 in A new species of Isthmura (Caudata: Plethodontidae) from the montane cloud forest of central Veracruz, Mexico

FIGURE 2. Holotype of Isthmura corrugata. A) Lateral and B) Ventral view. C) Coloration and form of costal grooves. D) Left hand (up) and left foot (down). E) Details of the head. F) Dorsal view. (G – H) Holotype (above) and paratype (below) dorsal and ventral coloration in preservation. All photographs by A. Sandoval-Comte

The environmental variables that make the greatest contribution in modeling the potential distribution of both species.

<p>Blue circles are the sites where the presence of <i>Parvimolge townsendi</i> was used for the model, and the orange triangles are those where the presence of <i>Thorius pennatulus</i> was used for the model.</p

Rate of finding <i>Parvimolge townsendi</i> and <i>Thorius pennatulus</i> per site.

<p>Each visit represents a search effort of 16 person hours.</p

Microhabitat use.

<p>Number of <i>Parvimolge townsendi</i> (A) and <i>Thorius pennatulus</i> (B) salamanders found in different microhabitats and at different times of the day.</p

Potential distribution of <i>Parvimolge townsendi</i> and <i>Thorius pennatulus</i>.

<p>(A) Potential distribution area for <i>P. townsendi</i>; black square are the sites used in to generate the model, (B) Potential distribution are for <i>P. townsendi</i>, cropped to include only the appropriate vegetation (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0034023#s2" target="_blank">Methods</a>), (C) Potential distribution area for <i>T. pennatulus</i>; black triangles are the sites used in to generate the model and (D) Potential distribution area for <i>T. pennatulus</i>, cropped to include only the appropriate vegetation. The colored area is the predicted distribution area and the black stars indicate large cities.</p

<i>Parvimolge townsendi</i> and <i>Thorius pennatulus</i>.

<p>A and B) Two <i>P. townsendi</i> males with different patterns of coloration (standard length = 20.7 and 23.8 mm, respectively). C and D) Two adult <i>T. pennatulus</i> salamanders (standard length = 17.8 and 16.8 mm, respectively).</p