Pachytriton airobranchiatus, Li & Yuan & Li & Wu, 2018

Li, Chen, Yuan, Zhiyong, Li, Haibin & Wu, Yunke, 2018, The tenth member of stout newt (Amphibia: Salamandridae: Pachytriton): Description of a new species from Guangdong, southern China, Zootaxa 4399 (2), pp. 207-219 : 212-216

Pachytriton airobranchiatus sp. nov. Li, Yuan and Wu

( FigS. 3–8 )

Holotype. SWFUYZY0301 ( FigS. 4–6 ), an adult male from Mt. Lianhua , Huidong County, Huizhou in Guangdong (23.0674°, 115.2364°, eleVation 980 m) collected by CL on May 17, 2017.

Paratypes. SWFUYZY0213 (adult male), SWFUYZY0214 (adult male), SWFUYZY0215 (adult male), SWFUYZY0216 (adult male), SWFUYZY0217 (adult female), SWFUYZY0218 (adult female), SWFUYZY0219 (juVenile), collected at the Same locality aS the holotype.

Diagnosis. The new SpecieS iS aSSigned to the genuS Pachytriton on the baSiS of following characterS: head oVal and flat; Skin Smoothly; bony ridgeS abSent; labial foldS diStinct on upper jaw; limbS Short; dorSal Vertebral ridge indiStinct; baSe tail broad and poSterior half gradually laterally compreSSed; dorSal caudal fin obViouS ( Wu et al. 2012a; Yuan et al. 2016). Pachytriton airobranchiatus sp. nov. iS diStinguiShed from itS congenerS by a combination of morphological characterS: (1) prominently eleVated diStal end of the epibranchial bone, Showing aS two conSpicuouS protruding bulgeS behind the head; (2) dorSal coloration can be either black-Spotted or unSpotted; (3) bright orange dotS abSent on dorSum; (4) coStal grooVeS abSent between axilla and groin; (5) finger I and toe I Slender, do not form aS Volar pad; (6) dorSal tipS of fingerS and toeS brown; (7) tipS of fore- and hind limbS could contact when limbS adpreSSed againSt body flank.

Comparisons. The moSt conSpicuouS morphological difference between P. airobranchiatus and itS congenerS iS itS prominently eleVated diStal end of the epibranchial bone. In addition, the new SpecieS differS from P. changi and P. xanthospilos by not haVing orange ribbon-like dotS on the dorSolateral Side (VS. both SpecieS haVing orange SpotS or blotcheS which extend ribbon-like along the dorSolateral SideS). Lacking coStal grooVeS between axilla and groin, Pachytriton airobranchiatus sp. nov. differS from P. inexpectatus , P. granulosus and P. feii . It further differS from P. wuguanfui by haVing brown dorSal tipS of fingerS and toeS in life (finger and toe tipS appear orange on the dorSal Side in P. wuguanfui ); and Slender fingerS I and toe I, which do not formS aS Volar pad (fingerS I and toe I extremely Short and formS aS Volar pad in P. wuguanfui ). It differS from P. moi by haVing orange blotcheS on Venter (VS. lack of orange blotcheS on Venter in P. moi).

Description of the holotype. Specimen in good StatuS of preSerVation. MeaSurementS giVen in Table 3. TTL 149.3 mm, TAL Shorter than SVL(TAL/SVL = 0.97); head oVal and flat, Slightly longer than wide (HW/HL = 0.81), rectangle in dorSal View; Snout truncate in both Ventral View and lateral View, protruding Slightly beyond lower jaw ( Fig. 4 ); noStril Small, located nearly to tip of Snout; eyeS Small (EL = 2.9 mm), eye diameter Smaller than Snout length (EL/SL = 0.40); the corner of the mouth tangent to the middle of eye in lateral View. labial fold diStinct on upper jaw; gular foldS obViouS; prominently eleVated diStal end of the epibranchial bone, Showing aS two conSpicuouS protruding bulgeS behind the head; Vomerine tooth SerieS Ʌ-like, located on front of maxillary; tongue Short and pad elliptical, adhereS to mouth floor with free lateral marginS; loreal region SlopeS Steeply downward anteriorly in lateral View; Skin Smooth; dorSal Vertebral grooVe inconSpicuouS; coStal grooVeS between axilla and groin abSent. Forelimb Short (AL/SVL = 0.15), tipS of forelimbS only reach the middle of eyeS when extended roStrally; fingerS Short and Slender, without webbing; lateral fringeS deVeloped Slightly ( Fig. 5 ); relatiVe length of fingerS I <IV <II <III. Hindlimb Short (PL/SVL = 0.20), but relatiVely longer than forelimb (AL/PL = 0.74), tipS of forelimbS and hind limbS are touched when adpreSSed to body flank; toeS Slender and eVident, without webbing; lateral fringeS deVeloped Slightly; relatiVe toe length I <V <II <IV <III; baSe tail broad and rounded, dorSal caudal fin conSpicuouS extendS from tail-baSe to tail-tip; Ventral caudal fin obViouS on poSterior of tail; tailtip Sharped. Cloaca Slit Short, not Swollen.

Color of holotype. In life ( Fig. 4 ), dorSal and lateral SurfaceS of head, body, and tail chocolate with black SpotS; Ventral SurfaceS of head light brown and mingled with milk white color; Venter brown and Scattered with Small, irregular, orange blotcheS; one irregular orange blotch around cloaca. Ventrally, freSh orange-red Stripe from tail-baSe to tail-tip. Six bluiSh white blotcheS near the tip of tail. Color did not change too much in preSerVatiVe after one week except for lighter color ( Fig. 6 ).

Variation. Table 2 SummarizeS the linear meaSurementS for all type SpecimenS. Unlike moSt Pachytriton , the new SpecieS haS both Spotted and unSpotted color morphS. DorSal and lateral black SpotS are abSent in SWFUYZY0214, SWFUYZY0215 and SWFUYZY0218 ( Fig 7 ). Ventral color pattern VarieS; SometimeS haVing black background with a few orange-red SpotS. Number, Shape and poSition of Ventral Small orange-red blotcheS VarieS among indiVidualS. One Specimen haVe no orange-red blotcheS on the Venter (SWFUYZY0215). BluiSh white blotcheS on tip of tail are only preSent in maleS. The cloaca iS larger in maleS than in femaleS.

Etymology. The Specific epithet iS deriVed from airo (G., raiSe) and branchos (G., gill), in reference to the prominently eleVated diStal end of the epibranchial bone of the new SpecieS.

Habitat. ThiS SpecieS inhabitS Small montane StreamS (1–2 m wide, Fig. 8 ) in broadleaf foreStS near the top of the mountain at eleVationS between 900 m to 1000 m. Large boulderS Scatter in the Stream. The flowing water iS Very clear and formS Small poolS during April. Water temperatureS ranged from 15.9 °C to 16.2 °C in the night of 30 April 2017. Water pH Value waS cloSe to 7 according to PH teSt Strip reading. Stream SubStrateS include graVelS, Scattered Small rockS, leaVeS and SandS. Many moSS and gladioluS grow on the boulderS. The Surrounding broadleaf tropical foreSt iS mainly compoSed of perSimmon tree ( Diospyros morrisiana ), Symplocos ulotricha , tea flower tree ( Camellia salicifolia and Schima superba ), holly tree ( Ilex ficoidea ), and beech ( Lithocarpus corneus ). Other amphibianS and reptileS that co-inhabit the Stream include Hong Kong caScade frog ( Amolops hongkongensis ), Fujian metacarpal-tubercled toad ( Leptolalax liui ), Short-legged horned toad ( Xenophrys brachykolos ), large odorouS frog ( Odorrana graminea ), piebald odorouS Frog ( O. schmackeri ), Boulenger’S keelback Snake ( Hebius boulengeri ), ChineSe Slug Snake ( Pareas chinensis ), Indian ForeSt Skink ( Sphenomorphus indicus ), and ChineSe water Skink ( Tropidophorus sinicus ).

Distribution and conservation. BecauSe LianhuaShan-Baipenzhu ProVincial Nature ReSerVe iS Situated in the tropical region and the genuS Pachytriton iS generally adapted for cold Stream water ( Wu et al. 2013), high annual temperature reStrictS the diStribution of the new SpecieS to high eleVationS near the top of the mountain, moStly in headStreamS. IndiVidualS of thiS newt SometimeS gather together in deeper poolS, but itS population Size SeemS much Smaller compared to other more common SpecieS Such aS P. brevipes and P. granulosus . Currently, the new SpecieS iS only known from the type locality and a neighboring mountain peak called Wuzhizhang, which are Separated from the former mountain by a Shallow Valley (eleVation about 300 m). The total extent of occurrence of thiS SpecieS iS eStimated to be around 10 km 2. Furthermore, the local tropical climate iS largely impacted by the EaSt ASian Summer monSoon, which bringS heaVy precipitation through a few rainStormS and hurricaneS in the wet SeaSon. In contraSt, precipitation iS minimal in dry SeaSon and thuS the Stream habitat may complete dry up. Such large fluctuation in rainfall amount poSeS a Significant threat to Pachytriton becauSe adultS cannot eaSily migrate from drying StreamS due to their aquatic SpecializationS ( Wu et al. 2012b). We conSider P. airobranchiatus sp. nov. to be facing a high riSk of extinction, and we recommend a conSerVation StatuS of Endangered (EN) in the IUCN Red LiSt of Threatened SpecieS according to criterion B1ac(ii) in CategorieS and Criteria VerSion 3.1, which SpecifieS the extent of occurrence eStimated to be leSS than 5000 km 2 and area of occupancy experiencing extreme fluctuationS ( IUCN 2017).

TABLE ³. Morphometric measurements (in mm) of Pachytriton airobranchiatus sp. nov. Holotype specimen is in bolđ. Abbreviations are đefineđ in the text.

Figures

FIGURE 3. Bayesian phylogram of Pachytriton inferred from the concatenated mitochondrial data set gene (nd2 and cytb). Asterisk denotes high support by Bayesian posterior probabilities (BPP> 95%), and bootstrap support values (BS> 70%). Long dash represents loW support values.

FIGURE 4. Dorsal vieW (A), lateral vieW (B) and ventral vieW (C) of the holotype (SWFUYZY0301) of Pachytriton airobranchiatus sp. nov. in life. Red arroW indicates the prominent epibranchial bone.

FIGURE 5. Dorsal (A) and ventral (B) vieWs of the hand, and dorsal (C) and ventral (D) vieWs of the foot of the holotype (SWFUYZY0301) of Pachytriton airobranchiatus sp. nov. in life.

FIGURE 6. Dorsal (A) vieW and ventral (B) vieW of the holotype (SWFUYZY0301) of Pachytriton airobranchiatus sp. nov. in preservative.

FIGURE7. Dorsal (A) vieW and ventral (B) vieW of paratype SWFUYZY0215 of Pachytriton airobranchiatus sp. nov. in life. Dorsal (C) vieW and ventral (D) vieW of paratype SWFUYZY0218 of P. airobranchiatus sp. nov. in life. Red arroW indicates the prominent epibranchial bone.

FIGURE 8. Habitat at the type locality of Pachytriton airobranchiatus sp. nov. in Mt. Lianhua, Huidong, Guangdong, China.