Limnonectes longchuanensis, Suwannapoom, Chatmongkon, Yuan, Zhi-Yong, Chen, Jin-Min, Hou, Mian, Zhao, Hai-Peng, Wang, Li-Jun, Nguyen, Truong Son, Nguyen, Truong Q., Murphy, Robert W., Sullivan, Jaqueline, Mcleod, David S. & Che, Jing, 2016

Suwannapoom, Chatmongkon, Yuan, Zhi-Yong, Chen, Jin-Min, Hou, Mian, Zhao, Hai-Peng, Wang, Li-Jun, Nguyen, Truong Son, Nguyen, Truong Q., Murphy, Robert W., Sullivan, Jaqueline, Mcleod, David S. & Che, Jing, 2016, Taxonomic revision of the Chinese Limnonectes (Anura, Dicroglossidae) with the description of a new species from China and Myanmar, Zootaxa 4093 (2), pp. 181-200 : 191-197

Limnonectes longchuanensis sp. nov. Suwannapoom, Yuan, Chen, Sullivan and McLeod

Holotype: Adult male (KIZ048424; Fig. 3 in life and Fig. 4 in preservative), from Longchuan, Dehong, Yunnan, China (24° 27' 32.40" N, 97° 45' 10.80" E, 1255 m a.s.l.), collected by Jin-Min Chen and Mian Hou on 14 August 2013.

Paratypes: Five paratopotypes and 9 paratypes from China and Myanmar: Four paratopotypes, KIZ048425(f), KIZ048426(f), KIZ048428(f), KIZ048429(f) from the type locality as above; one paratype KIZ048427(f) from Yingjiang, Yunnan, China (24° 32' 45.60" N, 97° 44' 32.40" E, 809 m a.s.l.); one paratype, CAS233014 (f) from Myitkyina District, Kachin State, Myanmar (25° 5' 38.2" N, 96° 22' 49" E); two paratypes, CAS232197(m), 232281(f) from Khandi District, Sagaing Division, Myanmar (25° 19' 20.6" N, 95° 31' 49.8" E, 744–847 m a.s.l.); one paratype, CAS221717 (f) from Mon Ywa District, Sagaing Division, Myanmar (22° 18' 50.1" N, 94° 24' 25.7" E); one paratype, CAS 210183 (m) from Alaungdaw Kathapa National Park, Sagaing Division, Myanmar (22° 18' 32.7" N, 94° 24' 25.8" E); four paratypes, CAS219994(m), 235006(m), 235132(m), 235133(f) from Min Dat District, Chin State, Myanmar (21° 22' 20.1" N, 93° 58' 34.6" E). Specimens numbered with KIZ (KIZ048425–29) and CAS (CAS233014, 232197, 232281, 221717, 210183, 219994, 235006, 235132, 235133) were deposited in KIZ and CAS, respectively.

Diagnosis. Limnonectes longchuanensis sp. nov. is assigned to Limnonectes based on the presence of fanglike odontoid processes on the lower jaw and male-biased size dimorphism (adult males characterized by hypertrophy of the head) (Emerson et al. 2000). Adults of the new species are diagnosed from congeners by a combination of the following characters: (1) a relatively large species of the L. kuhlii species complex; (male SVL = 54.9–77.87 mm, and female SVL = 40.6–63.0 mm); (2) tympanum obscured by thickened skin; (3) tubercles are widely present on dorsum, lateral surface of body, the dorsum of arms, thighs and tibia; (4) males with nuptial pads on fingers I only or both fingers I & II; (5) no temporal stripe or dark markings on dorsal sides of body and limbs; (6) males have longer and wider heads than females (male HL = 24.5–40.3 mm, HW = 23.1–36.0 mm; female HL = 16.6–24.5 mm, HW= 16.6–23.5 mm); (7) vocal sac and vocal slits absent in males; (8) throat and venter moderately pigmented; (9) relative finger length (longest to shortest) when adpressed: IV–V–III–II; (10) toe webbing is deeply excised between toes, webbing formula on foot = I0–0+II0+–0+III0+–0+V0+–0V.

Description of holotype. Adult male ( Figs 3–4 ). Head hypertrophied and broader than body, HL 53.4% of SVL; head longer than wide (HW 89.5% HL); rostrum rounded in dorsal view, projecting beyond lower jaw; acutely rounded and anteroventerally sloped in profile; nostril dorsolaterally oriented and in line with anterior mandibular margin, closer to tip of snout than to eye; internarial distance greater than interorbital distance; canthus rounded; lores sloping, shallowly concave with weak groove; distinct infraorbital groove from anterior margin of eye to posterior margin of eye continuing indistinctly, not reaching rictus; upper lip moderately straight and flared, reaching post-rictal tubercle; eye diameter 19.4% of head length; upper eyelid width 68.7% of interorbital distance; supratypanic fold moderate, extending from eye to angle of jaw (anterior insertion of arm); tympanic anulus not visible through skin. Vomerine teeth on oblique ridges, separated from each other by much less than width of one ridge. Choanne oval, perpendicular to longitudinal axis of body. Odontoid processes robust with blunt tips, length more than twice depth of mandible at base of process. Symphisial knob at mandibular symphysis. Tongue oval, wide U-shaped posterior notch. Vocal sac and vocal slits absent. IN 79.0% of IO; IN 7.8% of SVL; END 100.5% of IN; UEW 68.7% of IO; END 49.9% of RL.

Fingers: finger tips blunt, not expanded, without disk; relative length = IV>V>III>II, no webbing between fingers; palmar subarticular tubercle formula (digits indicated by Roman numeral): IV(2), V(2), III(1), II(1); proximal subarticular tubercles prominent, rounded, elevated on all fingers; distal subarticular tubercles low, flat and indistinct; thenar metacarpal tubercle large, oval, elevated; inner metacarpal tubercle oval, flat, equal in size to thenar tubercle, not contacting thenar tubercle; outer metacarpal tubercle smaller than inner tubercles, oval, elevate, contacting inner tubercle; prominent nuptial pad composed of minute spines covering entire upper surface of Digit II, extending on palmar surface to base of metacarpal tubercle. Tips of toes expanded into discs, toe pads elevated; decreasing lengths of toes: IV–III–V–II–I; toes webbed from base of toe pad, webbing deeply excised (webbing formula = I 0+–0+ II 0+–0+ III 0+–0+ IV 0+–0+ V); distinct, movable flap of skin on postaxial side of Toe V from base of toe pad to proximal end of metatarsus; distinct, movable flap of skin on preaxial side of Toe I from base of toe pad to level of inner metatarsal tubercle, continuing as raised ridge on distal two thirds of tarsus; subarticular tubercles prominent, elevated, oval ( Fig. 4 D–E); digits indicated by roman numeral (palmar subarticular tubercle count in parentheses): V (2), IV (3) III (2), II (1), I (1); inner metatarsal tubercle oval, elongate with elevated post axial border; TBL 44.1% of SVL; FEL 48.4% of SVL; LAL 21.3% of SVL.

Skin on top of head, throat, dorsal surfaces of forelimbs, and dorsum feebly crenulate; skin on sides rough with moderately dense, roundish, non-pearl tipped tubercles; skin around vent, “knee”, shank and foot distinctly tuberculate, covered with moderately dense, small, low tubercles with translucent spinules; ventral skin and dorsum of thigh smooth; pair of faint, broken dorsolateral folds extending from posterior of eye to vent.

Coloration: In life brown dorsally and laterally, some tubercles on sides of body appear to have white tops; one yellowish-brown bar on the center of dorsum extending through the center of upper lip to cloaca; rust colored patch near angle of jaw; lower lip with distinct dark brown bars separated by irregular white blotches; supratympanic fold dark brown, dark line extending through eye to nares; eye greyish with dark horizontal bar passing through pupil and faint vertical bar passing through; skin of arms and legs light brown; throat moderately pigmented, pigmentation extending onto chest at the level of pectoral girdle, abdomen white with faint brown flecking, ventral surface of thighs lightly mottled; webbing between toes dark brown with light mottling.

In preservative, brown dorsally and laterally; indistinct dark brown bars on upper lip, lower lip dark with light mottling; supratympanic fold dark brown; indistinct; throat heavily pigmented; venter immaculate, ventral portions of limbs mottled around margins; palmar and plantar surfaces dark brown, webbing between toes mottled with white margin on preaxial sides of digits II, III, IV, V and postaxial side of digit IV.

Variation. Variation in meristic and mensural characters among the type series shown in Tables 2 and 3. Males larger than females (SVL). Three of the male specimens in our series (KIZ048424, CAS 235006 and 235132) had nuptial pads only on the first finger whereas all other males had nuptial pads on the first and second fingers. Males with larger, more robust odontoid processes than females. One yellowish-brown bar either present or absent on the center of dorsum extending through the center of upper lip to cloaca.

Etymology. The specific epithet longchuanensis is derived from the name of the type locality, Longchuan, Yunnan, China.

Suggested common names: English: Longchuan big-headed frog.

Chinese name: Longchuan datou wa; (陇川大头蛙).

Comparisons. Limnonectes longchuanensis sp. nov. resembles other species in the L. kuhlii complex, but is genetically and morphologically distinct in comparison to other members of this complex (Table 6). Limnonectes longchuanensis sp. nov. can be distinguished from L. bannaensis by having large, raised tubercles on the dorsum, lateral surfaces of body, the dorsum of arms, thighs, and tibias (vs. lacking tubercles or having low tubercles on the dorsum, lateral surfaces of body, the dorsal surface of arms, thighs, and tibias in L. bannaensis giving this species the appearance of more smooth skin) ( Fig. 5 ).

Limnonectes longchuanensis sp. nov. differs from L. fragilis by having smaller subarticular tubercles and the possession of nuptial pads in males (vs. no tubercles and nuptial pads in males of L. fragilis ). In addition, the back of L. longchuanensis sp. nov. usually is without distinct ridges whereas L. fragilis possesses them. Limnonectes fragilis is endemic to Hainan Island (vs. L. longchuanensis sp. nov. does not occur in Hainan).

Limnonectes longchuanensis sp. nov. differs from L. fujianensis in that it normally lacks distinct ridges on the dorsum (vs. many ridges on the dorsum in L. fujianensis ). A dark brown W -shaped marking is visible on the dorsal view of the head of adult L. fujianensis (vs. W -shaped marking is not on L. longchuanensis sp. nov.). In addition, the tubercles of L. longchuanensis sp. nov. are larger and more densely arranged than in L. fujianensis .

Limnonectes longchuanensis sp. nov. can be distinguished from L. taylori , L. megastomias , L. isanensis , L. nguyenorum and L. jarujini by the presence of tubercles on the on lateral surface of body, the dorsum of arms and thighs (vs. lack of tubercles on the on lateral surface of body, the dorsal surfaces of arms and thighs in all four species). The first finger is longer than the second finger in L. longchuanensis sp. nov., which distinguishes the new species from L. taylori and L. jarujini (usually subequal first and second fingers in both species). Limnonectes longchuanensis sp. nov. is easily distinguished from L. namiyei by the lack of vocal slits (vs. presence of vocal slits in L. namiyei ).

TABLE 5. The pairwise uncorrected p distance (%) of mtDNA sequence between species of Limnonectes for 1928 bp of mitochondrial 12S rRNA, tRNA Val, and 16S rRNA genes.

Distribution. Limnonectes longchuanensis sp. nov. is presently known from China and Myanmar. In China, the species has been documented in Longchuan (type locality), Husa (24° 25' 22.80" N, 97° 52' 15.60" E, 1576 m a.s.l.), and Yingjiang (24° 32' 45.60" N, 97° 44' 32.40" E, 809 m a.s.l.), Yunnan, China. In Myanmar, it has been documented in Kachin State, Chin State and Sagaing Division ( Fig. 1 ). All specimens were collected in evergreen forests along hillside streams and small tributaries varying in width from 2 m to 5 m ( Fig. 6 ).

Figures

FIGURE 1. Sampling localities of the specimens of Limnonectes used in this study. New samples indicated by color: red stars in China = L. longchuanensis sp. nov., blue squares = L. fujianensis, pink diamonds = L. bannaensis, orange circles = L. taylori, and green triangles = L. fragilis. Samples downloaded from GenBank were indicated by white symbols. Locality numbers refer to Table 1 and Fig. 2.

FIGURE 3. (A) Dorsal view, (B) ventral views, (C) palmar view hand, and (D) ventral views of foot in male holotype of Limnonectes longchuanensis sp. nov. (KIZ 048424) in life.

FIGURE 4. (A) Dorsal view, (B) ventral views, (C) lateral view of head, (D) ventral views of foot and (E) palmar view of hand in male holotype of Limnonectes longchuanensis sp. nov. (KIZ 048424) after preservation.

FIGURE 5. Dorsal views and tuberculation of leg of (A, B) Limnonectes bannaensis [KIZ 022207; male, from Yunnan, China], (C, D) L. taylori [KIZ 022399; male, from Yunnan, China], and (E, F) L. longchuanensis scale bars = 10 mm.

FIGURE 6. (A) Longchuan, Yunnan, China, the type locality of Limnonectes longchuanensis sp. nov.; red arrow indicates Lonchuan forests where the new species was collected. (B) The relatively small size of habitat of the holotype in evergreen forests; red arrow indicates the closed canopy stream where the holotype of L. longchuanensis sp. nov. was collected.