Echinotriton maxiquadratus, Hou & Wu & Yang & Zheng & Yuan & Li, 2014

Hou, Mian, Wu, Yunke, Yang, Kelin, Zheng, Sheng, Yuan, Zhiyong & Li, Pipeng, 2014, A missing geographic link in the distribution of the genus Echinotriton (Caudata: Salamandridae) with description of a new species from southern China, Zootaxa 3895 (1), pp. 89-102 : 96-100

Echinotriton maxiquadratus sp. nov.

( Fig. 5–8 )

Chinese name: Gāo Shān Jí Yuán

English name: mountain spiny newt

Holotype. SY20131101ENT , an adult female collected under rocks on a mountain in southern China by Kelin Yang and Sheng Zheng on November 8, 2013. Coordinates and elevation data are deposited in the Institute of Herpetology and Liaoning Key Laboratory of Evolution and Biodiversity, Shenyang Normal University. An earlier search in May 2011 and a subsequent search in April 2014 did not recover additional specimens .

Diagnosis. This specimen is assigned to the genus Echinotriton based on its phylogenetic position derived from molecular data and the following morphological characters: flat body covered with tubercles of various sizes; an anteriorly curved bony spine on the posterolateral surface of the quadrate; a series of lateral glandular warts penetrated by distal rib extremities, which are free of muscle insertion. Echinotriton maxiquadratus sp. nov. can be diagnosed morphologically from congeners by the following combination of characters: a trapezoid projection behind the mouth corresponding to the quadrate spine (triangular projection in the other two species); a single row of 12 glandular warts on each side of body (extra 1–3 rows of smaller warts between lateral warts and the vertebral ridge in E. andersoni ); normal development of the 5th toe (rudimentary in in E. andersoni ); tip of longest finger exceeds tip of snout when forelimb is extended rostrally (approaching nostril in E. chinhaiensis ); skin tubercles are conical (ridge-like in E. chinhaiensis ).

Description of the holotype. A moderately sized female salamander with a depressed body.

Head. Flat, depressed, and wider than long. The shape is subtriangular. A trapezoid projection behind the mouth corresponding to the quadrate spine. Snout short and truncate, depressed on top. Lateral cranial ridge prominent, starting from the top of the snout over upper eyelids and reaching the parotoid gland posteriorly; the posterior end of the lateral cranial ridge slightly curved inward like a scroll. Median cranial ridges are pad-like and less prominent; anterior part depressed. Posterior to the median cranial ridge is a V-shaped ridge, which connects to the vertebral ridge. Parotoid gland flattened but distinct; much longer than wide and enlarged at the lateral side; the posterior end elevated to the same height as the lateral cranial ridge. Nostril rounded and small, very close to the anterior extremity of the lateral cranial ridge. Eye moderately large. Upper eyelid glandular, rather broad and visible from above; lower eyelid finely tuberculated. Tongue nearly round and about 1/3 width of the mouth; free from the bottom of the mouth at lateral and posterior margins. Skull very robust, wider than long (length of quadrate spine excluded). An oval fontanelle is present. Frontosquamosal arch complete and robust. Both quadrate and pterygoid extend anteriorly and form separate connections with maxilla.

Neck. More slender than the head and body. Gular fold distinct.

Body. A series of 12 glandular warts along each side of body. Thirteen trunk vertebrae. The first two warts are supported by the large epipleural process of the 3rd and 4th rib. The 3rd wart is supported by the distal extremity of the 4th rib. Remaining warts are supported by the distal extremity of 5th to 13th rib, respectively. The 3rd to 6th warts strongly extend laterally; sharp rib extremity can be seen piercing through these warts. The last five pairs of ribs are shorter in length and their distal portion flares dorsolaterally. A flattened vertebral ridge running from the V-shaped ridge on the head to the dorsal fin of the tail; vertebral ridge widest at the middle and tapers towards both ends.

Limbs. Relatively slender and long. Palm and sole overlap when forelimb and hind limb are adpressed against flank. Tip of longest finger exceeds tip of snout when forelimb is extended rostrally. Fingers and toes compressed with rounded tips. Four fingers; relative length 3> 2> 1> 4. Left forelimb has only 2 fingers probably due to early injury. Five toes with very rudimentary interdigital web; relative length 3> 4> 2> 1> 5. The 5th toe develops into normal size. Left hind limb has an extra distal phalanx on the 4th toe (an abnormal condition). Tubercles present on carpus and tarsus.

Tail. Laterally compressed. The ventral portion is much thicker than the dorsal portion. The sharp dorsal fin is the posterior continuation of the vertebral ridge. The ventral fin is less conspicuous and blunt. Posterior portion of the tail has been damaged and healed prior to collection. Only the first four caudal vertebrae bear short ribs.

Skin. Glandular conical tubercles of various sizes densely distributed on the dorsal side and flanks. The venter is covered with larger rounded tubercles. Transverse ventral wrinkles are present. Snout, lips, digits, palms and soles, and the ventral edge of tail do not have tubercles. Glandular pores most visible on lateral cranial ridges.

Color. Mostly black in life. Tip of the 2nd to 7th lateral warts are grayish yellow. Tip of the quadrate projection, digits, carpal and tarsal tubercles, cloaca, and the ventral edge of tail are yellowish orange.

Measurement (in mm). TTL: 129.47, SVL: 85.72, TAL: 43.75, AX: 39.01, CW: 16.69, AL: 26.32, PL: 27.62, HL: 18.28, HW: 25.81, HD: 9.92, SL: 6.77, ED: 4.48, IN: 5.31, ON: 6.12; IC: 6.94.

Etymology. The specific epithet maxiquadratus is derived from the combination of the Latin word maximus (greatest) and the quadrate bone, which refers to the large quadrate projection of the species. This name also brings to our mind Dr. Max Sparreboom, who extensively studies Old World salamanders and recently published a book with comprehensive descriptions and illustrations of those species.

Habitat. This species inhabits low depressions near the top of the mountain ( Fig. 9 ). Depressions are covered with dense tall grasses, rhododendrons, and melastomes. Marshland and lentic ponds intersperse in depressions. Humidity is so high that fogs form in most of the time. Showers are frequent. The specimen was collected from under a rock pile at the root of vegetation. Earthworms, harvestmen, and millipedes are abundant under rocks. Other amphibians include Hylarana latouchii , Nidirana adenopleura , and Bufo gargarizans . Polypedates braueri and Hyla chinensis can be found either on the ground or on vegetation.

Remarks. One hundred and twenty-two years after the description of E. andersoni and eighty-one years after that of E. chinhaiensis , we discovered a third species of Echinotriton . Standard scientific description of new taxa should include coordinates of collection sites, elevations, and geographic distribution. But in this paper, we choose not to reveal the detailed collecting information of E. maxiquadratus sp. nov. in the hope that illegal collection from hobbyists and pet dealers may be prevented. There are many examples showing how scientific descriptions ironically accelerate extinction of new species that are considered commercially valuable ( Stuart et al. 2006). Although one of our major motives to describe this salamander is to drive conservation hopefully through the joint effort from local and state government and the public, publicity can also backfire and create trading demands that outweigh potential benefit ( Meijaard & Nijman 2014). Species of Echinotriton and Tylototriton are among the topwanted salamanders in the international pet trade. Over the internet, Tylototriton spp. (mostly T. shanjing and T. verrucosus ) are traded at US $25–40 each and up. Echinotriton andersoni has a much higher price ( US $150–300 each) due to its restricted range. An extreme case is that of two wild-caught E. chinhaiensis that appeared in a pet store in Japan in 2012, where the salamanders were offered for sale at US $1400. Even though most species of the two genera are protected by law in their countries of origin ( Zhao 1998; Igawa et al. 2013), illegal collection remains a major threat to those salamanders.

The IUCN Red List of Threatened Species lists E. andersoni as endangered and E. chinhaiensis as critically endangered with as few as 300–400 breeding adults in the wild ( IUCN 2014, Liu et al. 2010). Echinotriton maxiquadratus sp. nov. likely suffers a similar level of population crisis. This species was unknown to science and even local people for a surprisingly long time despite dense human population and heavy human activity in this region, suggesting a very small population size. We did not encounter additional specimens in a previous and a subsequent search. It is highly likely that the new species will be pursued by hobbyists and pet dealers due to its rarity and, without immediate conservation action, will face the risk of extinction. The first two authors of this paper each have discovered new species of Chinese salamanders with very restricted ranges, which appeared in the pet trade shortly after publication of the description and disclosure of the collecting locality information (e.g., Cynops fudingensis, Wu et al. 2010b ; T. yangi and T. verrucosus pulcherrima, Hou et al. 2012 ). Given these precedents, we believe that only after effective conservation measures and legal protection status have been established for E. maxiquadratus sp. nov., should the locality information be released. Until then, such information can be requested from the Institute of Herpetology and Liaoning Key Laboratory of Evolution and Biodiversity, Shenyang Normal University. Meanwhile, we urge all hobbyists to refrain themselves from collecting this salamander or leaking locality information if encountered, and boycott any trading.

Along with threat from illegal collection, habitat destruction is another critical factor that can lead to rapid decline of E. maxiquadratus sp. nov. Part of the mountain has been converted into commercial plantations by local people. Empty pesticide bottles are frequently found. This mountain also attracts tourists, who set up tents near the collecting site. At a single night, over 50 tents were observed. The closest one was only 100 meters from where the salamander was found. These human activities are by no means sustainable to preserve the population. Therefore, we recommend E. maxiquadratus sp. nov. to be listed as critically endangered (CR) in the IUCN Red List of Threatened Species based on criteria A3 and B1(a, b).

Our discovery of E. maxiquadratus sp. nov. fills a gap in geographic distribution of the genus. Its range in southern China provides strong evidence for a once continuous distribution of Echinotriton from eastern coastal China to the Ryukyu Archipelago via a historical land bridge, through which many other mainland organisms including plants, insects, frogs, reptiles, and possibly mammals reached different islands in the archipelago (e.g., Ota 1998; Millien-Parra & Jaeger 1999; Matsui et al. 2005; Muraji et al. 2012; Shimono et al. 2013; Koizumi et al. 2014). One important biogeographic implication is that Taiwan, as the largest stepping stone in the land bridge, should be historically occupied by Echinotriton as well. Zhao & Adler (1993) reported three specimens of E. andersoni collected from northern Taiwan in 1935. But subsequent searches did not yield any additional specimens. The species is either believed extinct in Taiwan ( Zhao 1998) or its record is considered questionable ( Matsui & Ota 1995; Fei et al. 2006). The occurrence of E. maxiquadratus sp. nov. in southern China suggests that species of Echinotriton may still persist in Taiwan. Before our discovery, Echinotriton was considered to only inhabit broadleaf or broadleaf/bamboo-mixed forests at coastal foothills (elevation 100–200 m), which are in contrast to the habitat of E. maxiquadratus sp. nov. on higher mountains. Despite occupying lower latitudes, increased elevation, high air humidity, and dense vegetation can provide this terrestrial salamander with a cool and moist habitat. Therefore, future search for Echinotriton in Taiwan can expand to similar habitats.

Figures

FIGURE 5. Dorsal, lateral, and ventral view of the holotype of E. maxiquadratus sp. nov. (SY20131101ENT). Penetrated sharp rib extremities (red arrows) are visible at lateral warts in the dorsal view.

FIGURE 6. Lateral, dorsal, and ventral close-up view of the head of specimen SY20131101ENT.

FIGURE 7. Close-up view of the right hand, right foot, and left foot of specimen SY20131101ENT. The 4th toe of the left foot has an extra phalanx.

FIGURE 8. Radiograph of specimen SY20131101ENT. The quadrate spine unique to Echinotriton is visible.

FIGURE 9. Habitat of E. maxiquadratus sp. nov. Left: the rock pile where specimen SY20131101ENT was collected; right: another view near the mountain top.