Holotype: adult male NWIPB 770650.

(Fig. 3A, F, K, P, U; Suppl. material 1: Table S1). Measurements in mm. Adult male. Body moderate, SVL 35.7; a large swollen arc-shaped protuberance present on vent beyond cloaca and visible on both dorsal and lateral view, its length 6.8 (measured dorsally), width 4.7, and thickness 2.7.

Head wider than long (HW/HL 1.13); snout blunt in dorsal view, obtusely protruding beyond mandible in lateral view; rostral appendage absent; canthus rostralis well developed, loreal region concave; dorsal surface of snout slightly concave; nostril oval, slightly closer to snout than eye (EN/SN 1.04); eyes lager than twice tympanum (EL/TYD 2.24); eye-tympanum distance smaller than tympanum diameter (TYE/TYD 0.86); tympanum oval, obliquely orientated, upper 1/3 concealed with supratympanic ridge; interorbital space flat, wider than upper eyelids (UEW/IUE 0.89); pineal ocellus not visible; vomerine ridges well developed, acutely angled, enlarged at ends where bearing several vomerine teeth; maxillary teeth present; tongue notched posteriorly, medial lingual process absent.

Forearm moderately long and wide; fingers long and thin, without webbing and lateral fringes; subarticular tubercles absent; inner and outer metacarpal tubercles small and oval, weakly connected at lower half; finger relative lengths I < II < IV < III; base of finger I strong, larger than base of finger II; tips of fingers slightly swollen and rounded (FIIIW 0.8), without pads.

Hindlimbs relatively thin and long; thighs ca. equal length of shanks and feet; toes long and thin, relative lengths I < II < V < III < IV; tips of toes rounded; toes rudimentary webbed; lateral fringes narrow; continuous dermal ridges present under toes; outer metatarsal, and subarticular tubercles absent; inner metatarsal tubercle distinct, rounded, separate from base of toe I at a distance nearly twice its diameter; tips of toes rounded.

Dorsal surface of head and body relativity rough, densely scattered with small granules; temporal region and upper corner of mandible scattered small granules; tympanum border slightly raised; upper eyelid without pointed edge; supratympanic ridges extend from posterior upper eyelid border to region above forearm insertions, not curving above tympanum, rear part thicker than front; flanks densely covered with small granules and scattered several larger tubercles; two longitudinal ridges on dorsolateral body distinct, nearly parallel, extending from above shoulder to nearby groin; parietoscapular-sacral ridges forming a “> <” configuration, composed by rows of small tubercles, dorsal surface of forearm thighs and shanks with several rows of small tubercles transversely arranged; dorsal upper arm and other dorsal surfaces of hindlimbs covered with dense small granules; ventral surface of body and limbs smooth; pectoral glands small (diameter 0.8) and rounded, close to axilla on chest; femoral glands small (diameter 1.0) and rounded, closer to outer edge of knee than to cloaca.

(Fig. 3A, F, K, P, U). Dorsal and lateral surface of body, dorsal surface of head mostly tan; a brown triangle present between eyes, little lighter in center, anterior corners reach to near out edge of upper eyelids; indistinct “X”-shaped markings on dorsum, with small tubercles in center; darker brown stripe along with dorsolateral ridges; tubercles on flanks white, edged with dark patches; lateral surface of head tan with brown stripes radiating from orbit to upper mandible and upper eyelid; iris dark brown; a brown stripe extending from posterior corner of orbit under former half supratympanic ridges to behind tympanum, a clear thin dark stripe under edges of supratympanic ridges after tympanum, no long white stripe present on upper lip; dorsal and lateral surface of limbs mostly tan, two broad brown transverse bands on forearms, and four thin indistinct transverse bands on dorsal thighs and shanks; dorsal tarsal pale gray with three indistinct transverse bands, outer three fingers with tan blotches; gular region and chest dusty tan with a short longitudinal brown stripe in middle of throat; two light patches on edges of jaw corresponding anterior corners of eyes and front edge of brown stripe at posterior end of jaw; and one brown stripe extending from posterior end of jaws to base of forearms on both sides; abdomen dusty tan, with a dozen darker patches on middle and upper abdomen, large longitudinal dark patches present on ventral lateral abdomen hardly present; ventral surface of forelimbs and hindlimbs dusty tan mottled with light patches; pectoral and femoral glands light tan.

According to Huang and Fei (1981): dorsum brown or dark brown; two to four dark colored transverse bands present on forearms; and four to five dark colored transverse bands present on thighs and shanks; places around cloaca, groin, and anterior, posterior, ventral thigh orange; tips of fingers and toes light red; ventral surfaces of tarsi, metatarsus, and toes grayish brown or black-brown; lateral and ventral surface with lots of grayish black spots; a longitudinal short grayish black stripe present on middle throat; granules on dorsal surface of body and limbs light red.

(Fig. 5A, F). Description based on scan of the holotype. Skull weakly ossified, width 1.12× of length; maxillary overlapping with the quadratojugal; premaxillary and maxillary teeth strong, most tooth closely positioned with others, 9/9 teeth present on left/right premaxillary, no teeth present on mandible; vomerine ridge well developed, two vomerine teeth present on enlarged posterior end of each vomerine ridge; nasal process of premaxilla protruding beyond skull; nasal bones separated from each other, inner edge mostly contact with sphenethmoid; sphenethmoid relatively smooth with few small pits on both dorsal and ventral surface, the middle one third of front edge not contacting nasal bones and truncate, separated from premaxilla; frontoparietal divided by a distinctly opening sagittal suture, sagittal suture slightly wider posteriorly; anterior fontanelle small, only slightly wider than sagittal suture; front and rear part of frontoparietal almost equally wide; posterior edge of exoccipitals posterior to the line connecting conjunctions of quadratojugal and mandible; pterygoid moderate; anterior process of squamosal slender and sharp, tip closer to the junction of pterygoid and quadratojugal than its base, posterior process present; prootic relatively smooth, separated from exoccipitals; anterior process of parasphenoid in shape of fusiform, anterior part not raised above sphenethmoid, conjunction of parasphenoid anterior process meet with sphenethmoid moderate, width ca. three quarters of the constriction near its base; columella auris short.

See for morphometric variation within the three types (two adult males and one adult female) in Suppl. material 1: Table S1. According to the photo of dorsal view of the only adult male paratype NPIB 770651 presented by Fei and Yei (2016), the adult male paratype resemble the holotype in general, also has a distinct swollen arc-shaped protuberance present on end of body beyond cloaca, but different in color on dorsal body darker, and not having distinguishable “X”-shaped markings on dorsum. The adult female allotype NPIB 770652 do not have a distinct projection on vent, and the coloration on dorsal and ventral surface of body lighter than males.

Male with gray nuptial pad on inner side of the first finger, spines on nuptial pad dense and small; single subgular vocal sac; vocal sac opening small, slit like; a distinct fatty swollen rounded projection present on the end of body beyond cloaca.

According to Huang and Fei (1981), this species was first collected at elevation 1530 m in the type locality, Gelin, Medog, Xizang, China; two adult males were found on shrubs emitting continuous calls sounds like “gazhi...gazhi...gazhi...” to the human ear; the female was found on the road near a brook.

Megophrys pachyproctus differs from all other known congeners except M. koui and M. caudoprocta by having a distinct protuberance above vent, and further differs from the latter two species in protuberance above vent being swollen and arc-shaped (vs. not). For comparisons with subsequent undescribed species covered in this paper, refer to relevant morphological comparison sections for those species.

Megophrys pachyproctus was originally described by Huang and Fei (1981) with description and figures of the holotype, measurements of types, secondary sexual characters, and brief natural history. And then were translated into English and measurements of snout length, internasal space, interorbital space, eyelid width, diameter of eye, tympanum, and tibia width were supplemented by Huang et al. (1998). Fei et al. (2009) provided illustration of the holotype. Fei et al. (2010) and Fei and Ye (2016) provided colored drawings of the holotype and the paratype (NPIB) 770651, and colored photos of dorsal and lateral views of one living topotype from Medog (photographs by Ke Jiang). The topotype possess expanded fingertips with small disk and two large longitudinal dark patches on ventral lateral abdomen (while the holotype of M. pachyproctus does not have these character), and not having a distinct swollen arc-shaped protuberance present above vent (while the holotype of M. pachyproctus possess). Li et al. (2010) provided similar photos of a living specimen and measurements of seven specimens from Maniwong and Yarang, Medog, under the name M. pachyproctus. The body length of these specimens ranges from 26.1 mm to 27.9 mm, and Li et al. (2010) cited the body length of the male types of M. pachyproctus as 25.3 mm to 36.2 mm, which should be 35.3 mm to 36.2 mm (Huang and Fei 1981). These specimens with small body size, expanded fingertips with small disk, and two large longitudinal dark patches on ventral lateral abdomen turn out to be mostly similar with Megophrys yeae sp. nov. (see description of Megophrys yeae sp. nov.). We suggest reexamination of these specimens should be taken. Saikia and Sinha (2018) reported M. pachyproctus from Southern Xizang (27.547681°N, 93.897555°E, 1855 m), provided description, measurements (body length 37.8), and a photo of dorsal view of the single male voucher specimen V/A/NERC/1352. But the photo does not present an arc-shaped swelling above vent (Saikia and Sinha 2018: fig. 3A) as the holotype. We suggest further examination should be made to confirm the identification of the specimen. This species was also reported new range in Lao Cai and Ha Tinh Province, Vietnam (Orlov et al. 2002; Nguyen et al. 2005). Since Megophrys inhibits astonishing cryptic species biodiversity, and species like M. pachyproctus thought to be widespread from Southwest China to Vietnam confirmed to be another species (Chen et al. 2016; Tapley et al. 2017; Liu et al. 2018), records from Vietnam where more than 1000 km from type locality should be questioned and specimens should be reexamined.

Five adult females and six adult males from Medog (Suppl. material 1: Table S1).

Refer to Fei et al. (1983) for holotype description, Mahony et al. (2018) for picture of holotype CIB 73II0015, Fei et al. (2009) and Fei and Ye (2016) for description of coloration and picture of topotypes.

Skull. (Fig. 5B, G). Description based on sequenced adult male topotype CIB022017061406. Skull well ossified, width 1.21× length; maxillary overlapping with the quadratojugal; premaxillary and maxillary teeth well developed, and closely positioned with others, 11/13 teeth present on left/right of premaxillary; vomerine ridge robust; few vomerine teeth strong, present on posterior end of vomerine ridge; nasal process of premaxilla protruding beyond skull; nasal bones separated, posterior one third of inner edge contact with sphenethmoid; frontoparietal distinctly wider in front than rear; sphenethmoid relatively smooth with few small pits on dorsal and ventral surface, the middle half of front edge not contacting nasal bones and protruding forward, separated from premaxilla; frontoparietal not divided, sagittal suture occlusive; anterior fontanelle occlusive; front part of frontoparietal distinctly wider than rear; posterior edge of exoccipitals anterior to the line connecting conjunctions of quadratojugal and mandible; pterygoid robust; anterior process of squamosal slender, tip much closer to the junction of pterygoid and quadratojugal than its base, posterior process present; prootic relatively smooth, separated from exoccipitals; anterior process of parasphenoid in shape of fusiform, the front part raise above sphenethmoid from ventral view, the conjunction with sphenethmoid with width equals the constriction near base of anterior process of parasphenoid; columella slender and long.

Adult female generally with larger body size. Average body length females 79.7 mm (n = 5, 75.7–85.5 mm), male 65.3 mm (n = 6, 63.1–68.7 mm). Males with brown nuptial pads on fingers I and II, spines on nuptial pad dense; single subgular vocal sac.

(Fig. 6A, B, E, F, I, J, M, N; Suppl. material 1: Table S2). For low-middle-elevation tadpoles of M. medogensis, description was based on tadpole CIBMT20170621 (stage 35) which shared the same pond of sequenced tadpole CIBMT022017061808 in Bari village. They are similar on morphology. For coloration at stage 26, description based on sequenced specimen CIBMT1710101 from Yadong village. Measurements in mm. For stage 35, body 13.3, elongated; head slightly narrower than trunk, oral disk large, funnel like, 1.2× body width; three rows of short oval submarginal papillae on lower lip; middle of lower lip protruding forward, with five rounded papillae longitudinal arranged from the tip middle lower lip to oral cavity; corner of mouth with six papillae arranged in a transverse row on both sides; three transverse rows of short oval papillae on upper lip; keratodonts absent; nares closer to eyes than tip of snout (RN/NE 1.6); eyes round, positioned dorsolaterally; internarial distance (IND 3.0) 61% of the interpupilar distance (PP 4.9); spiracle mostly in left side of body, in right-handed helix from ventral view; spiracular tube not protruding beyond body wall, positioned 60% of the distance between tip of the snout and trunk-tail junction, and below the horizontal mid trunk line; tail accounts 69% of total length; dorsal fin arise above trunk-tail junction, 35% of maximum body height; ventral fin connected to the trunk, with lesser height, 27% of maximum body height; anal siphon opens medially; maximum tail muscle height 72% of maximum body height, maximum tail muscle strong, width 53% of maximum body width; 12 small curves present on both lateral side of tail muscle. For stage 26, dorsal fin arises behind trunk-tail junction. For stage 43, clear “X” and “l_l” skin ridges have present on dorsum, limbs are well developed. For high-elevation tadpoles of M. medogensis, description mostly based on sequenced tadpole CIBMT171001 (at stage 27), coloration based on sequenced tadpoles CIBMT1710106 and CIBMT1710112, collected from Gedang, Medog, Tibet Autonomous Region, China (29.463916°N, 95.769507°E, 2142 m). Body 9.5, elongated; head slightly narrower than trunk; oral disk moderate, funnel like, positioned anterior-dorsal, width equal with body width; 5 transverse rows of short oval papillae on upper lip; keratodonts absent; nares much closer to eyes than tip of snout (RN/NE 2.2); eyes round, positioned dorsolaterally; internarial distance (IND1.9) 61% of the interpupil distance (PP 3.2); spiracle barely visible from ventral view; the spiracular tube not protruding beyond body wall, positioned 63% of the distance between tip of the snout and trunk-tail junction, and below the horizontal mid trunk line; tail accounts 72% of total length; dorsal fin arise above anal siphon opens, 40% of maximum body height; ventral fin connected to the trunk, with lesser height than dorsal fin, 37% of maximum body height; anal siphon opens medially; tail muscle relatively weak, maximum height 72% of maximum body height, width only 44% of maximum body width; eleven small curves present on both lateral side of tail muscle.

Figure 6. 

Tadpole specimens of four groups of three Megophrys species from Medog. A–D dorsal views of the low-middle-elevation tadpole CIBMT20170621 of M. medogensis (Goser stage 35), the high-elevation tadpole CIBMT171001 of M. medogensis (stage 27), tadpole CIBMT20170611 of M. cf. pachyproctus (stage 25), tadpole CIBMT170604 of Megophrys yeae sp. nov. (stage 35), respectively E–H lateral views of the tadpoles, respectively I–L ventral views of the tadpoles, respectively. M–P dorsal views of head of the tadpoles, respectively. Scale bar for body view equal to 10 mm, and for head view 2 mm.

Coloration of tadpoles. Low-middle-elevation tadpoles. In preservation (based on CIBMT20170621; Fig. 6A, B, E, F): dorsal body brown; lips semitransparent, papillae on lips brown; dorsal tail light brown, marbled with deep brown markings; lateral side of tail densely covered with tiny brown pigment spots, also mottled with small light colored patches, and scattered with deep brown pigments piles; fins semitransparent; ventral surface of body semitransparent, sparsely covered with brown pigments. In live: dorsal and lateral body generally in light yellow-brown; lateral side of tail mottled with light colored patches; ventral body without white patches; iris brown.

High elevation tadpoles (Fig. 6I, J, M, N). In preservation: dorsal body and tail with brown pigmentation; lateral body brown, skin coloration lighter below spiracular tube, with clear white patches; lateral tail muscle brown mottled with dense tiny white dots; upper and lower fin semitransparent brown, lower fin colored lighter; no dark patches on lateral and dorsal tail; ventral body semitransparent white, stained with light brown pigments; lips semitransparent white, papillae brown. When alive, dorsal body and tail basically deep brown, mottled with copper pigmentation, especially dense on body; lateral body brown, with cream-white patches near abdomen; lateral tail brown, scattered with tiny white pigment spots, no dark brown patches on tail; ventral surface of body semitransparent brown, covered with small white pigments; iris brown.

(Fig. 4A, D, G, J; Suppl. material 1: Tables 4; Suppl. material 2: Fig. S3). A total of 16 call groups and 62 calls were analyzed. Average dominant frequency of calls low, 2.5 kHz (2.3–3.0 kHz); call repetition rate moderate, average 1.2 calls per seconds; call interval short, average 153–254 ms; call groups with average 10.8 calls; call duration long (average 746 ms), and with lots of notes (average 42.1). To the human ear, the call sound like “ga ga ga...”.

The species is currently known with certainty from the type locality in Medog County, and its distribution elevation was recorded between 680–2200 m (Fei et al. 1983, 2012, Fei and Ye, 2016; this study). This species was recorded in or near small mountain streams of tropical rain forests, sit on rocks, leaf litter, and sometimes bare soil. Calls heard between 11 June to 5 August (this study; Fei et al. 2019). Four in five females recorded during 11 June to 18 June were gravid. Males start calling before dusk under dense vegetation. Normally, two or more males call in small groups along stream banks, spacing themselves ca. 3–5 meters from each other. Sequenced tadpoles in metamorphosis were recorded on 18 June, in small mountain stream pond at 1560 m. Tadpoles of two other species of Megophrys share the same ponds. See description in following. Breeding season is supposed to including early June and may last to early August.

Refer to Mahony et al. (2018) for comparison with other species of M. major group. M. medogensis differs from M. pachyproctus by much larger body size (SVL 57.2–68.7 in 21 males vs. 35.3–35.7 in two males in the latter), absence of large protuberance above vent (vs. present in the latter), skin relatively smooth (vs. rough in the latter), frontoparietal distinctly wider in front than rear (vs. almost equally wide in the latter), sagittal suture occlusive (vs. distinctly open in the latter), and columella auris long (vs. short in the latter). For comparisons with species studied in this paper, refer to relevant morphological comparison sections for those species.

Four adult males, CIB022017061805 (Figs 3C, H, M, R, W, 5C, H, 7), CIB201706MT04, CIB022016061806, CIB022017061807, collected from Bari village, Medog County, Tibet Autonomous Region, China (29.32947°N, 95.36016°E, 1780 m) by SC Shi and L Ding, on 18 June 2017. One adult male (CIBMT171056), four adult females in gravidity (CIBMT171052, CIBMT171057, CIBMT171058, CIBMT171054), and one male toadlet (CIBMT171059) were collected from vicinity of Renqingbeng Temple (29.304832°N, 95.361682°E, 2003 m) by SC Shi on 26 October 2017.

Adult male, CIB022017061805 (Figs 3C, H, M, R, W, 5C, H, 7). Measurements in mm. Body stout, relatively small size (SVL 34.8); protuberance beyond cloaca small, barely visible from ventral view, not swollen.

Head moderately large, wider than long (HW 12.3, HL 11.0, IFE 6.5, IBE 10.4); snout rounded in dorsal view, slightly projecting in profile, protruding beyond lower jaw; rostral appendage absent (SL 4.6); canthus rostralis blunt; loreal region concave, dorsal surface of snout slightly concave; nostril oval, nearly in the middle of distance from snout to eye (SN 2.2, EN 2.3), distance between nostrils almost equal to distance between upper eyelids (IN 3.9, IUE 3.8); tympanum smaller than half of eyes (EL 4.5, TYD 1.8); eye-tympanum distance subequal to tympanum diameter (TYE 1.7); tympanum irregular rounded, upper 1/3 conceal with supratympanic ridge; interorbital space flat, larger than upper eyelid (UEW 3.2); pineal ocellus not visible; vomerine ridges distinct, orientation of two ridges acutely angled, enlarged at ends where bearing several vomerine teeth; maxillary teeth present; tongue notched posteriorly, medial lingual process absent.

Forearm moderately long and wide, similar size of upper arms, shorter than hand (FAL 7.5, HAL 9.6); fingers long and thin, with rudimentary webbing; narrow lateral fringes present on finger III, indistinct on other fingers; subarticular tubercles absent; inner and outer metacarpal tubercles mostly fused, large, with the size of base of finger I; finger length formula I < II < IV < III; base of finger I strong, larger than base of finger II; tips of fingers slightly swollen, without pads (FIIIW 1.1).

Hindlimbs thin and long; tibio-tarsal articulation reaches middle eye; thighs shorter than shanks but longer than feet (TL 16.5, SHL 17.2, FOL 15.2, TFOL 24.0); toes long and thin, relative lengths I < II < V < III < IV, rudimentary webbed, with narrow lateral fringes, tips rounded, dermal ridges continuously present on ventral surface; subarticular tubercles absent; outer metatarsal tubercle tiny and rounded; inner metatarsal tubercle distinct (IMT 1.6), nearly oval, partially fused with toe I.

Skin. Dorsal surface of head and body rough, densely scattered with small granules; temporal region and upper corner of mandible with rough granules; tympanum ring slightly raised; several small granules on edges of upper eyelids; supratympanic ridges extend from posterior upper eyelids to above forearm insertions, curving above tympanum, rear part thicker than the front; skin on flanks smoother than skin on dorsum, with several large warts and lesser granules; dorsolateral ridges distinct, irregularly stretch from above shoulder to near groin; a transverse skin ridge between upper eyelids; a near “V”-shaped skin ridge between shoulders, connected with the right dorsolateral ridge by a short skin ridge, a tubercle present near the end of “V”-shaped skin ridge; two oblique skin ridges connected with dorsolateral ridges at posterior; dorsal surface of upper arm covered with small granules in three rows from shoulder to elbow; small granules on dorsum of lower arm, hand, and hindlimbs, four transverse rows of granules on thighs and shanks; ventral surface of body and limbs smooth; pectoral glands small and rounded, with the size of first fingertip, close to axilla on chest; femoral glands small, closer to outer edge of knee than to cloaca.

(Fig. 3C, H, M, R, W). Dorsal surface of head gray; dorsal surface of body pale gray; a darker gray triangle bet between eyes, little lighter in center, anterior corners reach to near out edge of upper eyelids; area around dorsal skin ridges darker, no clear “X”-shaped markings on dorsum; tubercles on flanks white and edged with dark patches on one side; lateral surface of head mottled with pale gray and grayish white; a dark stripe extend from behind upper eyelid to behind corners of the mouth, thicker in the middle, and covers tympanum entirely; no long white stripe present on upper lip; two dark strips from eyes to upper lips, two short dark bands on upper lips before eyes; iris dark covered with silver pigments radiated from pupil; dorsal and lateral surface of limbs pale gray with darker transverse bands, one or two broad dark brown transverse bands on forearms, and four indistinct transverse bands on dorsal thighs and shanks, dorsal tarsal pale gray with three indistinct transverse bands, dorsal surface of fingers and toes also covered with several darker transverse bands; gular and chest dusty white; edge of lower mandible white with five brown patches, the pair corresponding to places between nasals and eyes are largest; a short longitudinal light brown stripe present in middle of throat, two pairs of faint brown patches beside the short longitudinal light brown stripe; a brown stripes extending from posterior end of jaws to base of forearms on both sides; skin around pectoral glands faint brown, three medium size faint brown patches present on dusty white upper abdomen, lower abdomen cream-white reticulated with dusty brown pigments, no large longitudinal dark patches present on ventral lateral abdomen; ventral surface of forelimbs and hindlimbs dusty brown, mottled with several irregular brown patches; pectoral and femoral glands cream-white; nuptial pad grayish black.

(Fig. 7). Markings as described in preservative; flanks, lateral sides of head, dorsal surface of head, body, and limbs light brown in general with orange-red granules; tympanum and stripes under eyes brown; several cream-white dots present on flanks; two dark brown transverse bands present on forearms; four dark brown transverse bands present on thighs, shanks, and tarsi; ventral surface of head, and abdomen grayish white basically, two large longitudinal brown present on lateral sides of abdomen; chest, ventral surface of hand, thigh, and feet flesh colored; skins around cloaca, on groin, and anterior, posterior and ventral thigh without orange patches; iris dark brown reticulated with dense golden pigments, pupil edged with diamond-shaped golden ring; nuptial pad gray.

Figure 7. 

The adult male CIB022017061805 of M. cf. pachyproctus in life. A dorsolateral view of body B ventral view of body C dorsolateral view of head D ventral view of hand E ventral view of foot.

(Fig. 5C, H). Skull weakly ossified, width 1.15× of length; maxillary overlapping with the quadratojugal; premaxillary and maxillary teeth weakly developed, most tooth separated from others by a distinct gap, 10/10 teeth present on left/right premaxillary, teeth absent on mandible; vomerine ridge moderate, few vomerine teeth weak, present on enlarged posterior end of vomerine ridge; nasal process of premaxilla protruding beyond skull; nasal bones separated from each other, half connected with sphenethmoid; sphenethmoid rough with curves and pits on dorsal and ventral surface, middle one third of front edge free from nasal bones, and protruding forward, separated from premaxilla; frontoparietal divided by a distinctly open sagittal suture , slightly wider posteriorly; anterior fontanelle small, slightly wider sagittal suture; front and rear part of frontoparietal almost equally wide; posterior edge of exoccipitals posterior to the line connecting conjunctions of quadratojugal and mandible; pterygoid moderate; anterior process of squamosal slender and sharp, tip closer to the junction of pterygoid and quadratojugal than its base, posterior process present; front part of prootic smooth, rear part rough, separated from exoccipitals; anterior process of parasphenoid in shape of fusiform, anterior part not raised above sphenethmoid, conjunction of parasphenoid anterior process meet with sphenethmoid narrow, width ca. half the constriction near its base; columella auris short.

(Suppl. material 2: Fig. S2). The topotypes have the following differences: tympanum diameter/eye diameter ratio varies from 0.40 to 0.60 for adults, 0.36 for the juvenile CIBMT171059; skin ridges between dorsolateral ridges on dorsum vary in configuration, i.e., “> <” (CIB022016061806) and “>” (CIB022017061807); and specimen CIB022017061807 with orange-red patches on groin, and flanks stained with orange-red. The three skulls similar in morphology (e.g., premaxillary and maxillary teeth weak; the nasal bones half connected with sphenethmoid; the sphenethmoid rough and protruding forward; tip of anterior process of parasphenoid narrow), but possessing following variation: vomerine teeth only present on left vomerine ridge of CIBMT171056; sagittal suture of CIBMT171056 partially occlusive near the center.

Adult female with larger body size, average 1.17× of males. Male with gray nuptial pad on inner first finger, spines on nuptial pad dense and small; single subgular vocal sac; vocal sac opening small, slit like; lineae musculinae absent.

(Fig. 4B, E, H, K; Tables 4; Suppl. material 1: Table S3). A total of 15 call groups and 82 calls were analyzed. Average dominant frequency of calls moderate, 3.2 kHz (3.2–3.3 kHz); call repetition rate moderate, average 0.9 calls per seconds; call interval long, average 493–720 ms; call groups with average 10.8 calls; call duration long (average 746 ms), and with lots of notes (average 42.1). To human ears, sound like pebbles hitting ground continuously.

(Fig. 6C, G, K, O; Suppl. material 1: Table S2). Description based on measurements and observation of tadpole specimen CIBMT20170611 at stage 25. Measurements in mm. Body 6.1, elongated; head slightly narrower than trunk; oral disk large, funnel like, positioned anterior-dorsal, width 1.6× of body width; 4 rows of oval submarginal papillae on middle lower lip, 3 rows of oval submarginal papillae on both sides of upper lips; all these papillae range towards oral cavity; keratodonts absent; nares much closer to eyes than tip of snout (RN/NE 3.8); eyes round, positioned dorsolaterally; internarial distance (IND1.4) 85% of the interpupil distance (PP 1.63); spiracle mostly in left side of body, in right-handed helix from ventral view, the spiracular tube not protruding beyond body wall, positioned 63% of the distance between tip of the snout and trunk-tail junction, and below the horizontal mid trunk line; tail accounts 68% of total length; dorsal fin arise above trunk-tail junction, 38% of maximum body height; ventral fin connected to the trunk, with lesser height than dorsal fin, 31% of maximum body height; anal siphon opens medially; maximum tail muscle height 72% of maximum body height, maximum tail muscle width 53% of maximum body width; eleven small curves present on both lateral side of tail muscle.

When alive, dorsal body and tail basically with yellow-brown pigmentation; two golden spots in size of eyes present on dorsolateral mid body. In preservation, dorsal body, and most part of lateral tail with brown pigmentation; ventral body and tail fin semitransparent; lateral body and tail with pigmentation, but lower fin and ventral body barely pigmented.

By having relative smaller body size (males 33.6–36.6, n = 5; females 40.6–42.8, n = 4; measurements in mm), Megophrys cf. pachyproctus differs from M. medogensis (males 57.2–68.7, n = 21), M. caudoprocta (males 70.8–81.3, n = 4); M. hoanglienensis (males 37.4–47.6, n = 11), M. jingdongensis (males 53.0–56.5, n = 3), M. liboensis (males 61.6–62.9, n = 4), M. omeimontis (males 56.0–59.5, n = 10), M. aceras (males 55.8–62.4, n = 6); M. ancrae (males 39.1–45.3, n = 8), M. damrei (male 57.1, n = 1), M. flavipunctata (males 56.9–68.4, n = 4), M. glandulosa (males 76.3–81.0, n = 10), M. himalayana (males 68.0–73.5, n = 6), M. lekaguli (males 55.6–66.6, n = 8), M. major (males 71.6–87.5, n = 12), M. mangshanensis (male 62.5, n = 1), M. maosonensis (male 77, n = 1), M. megacephala (males 45.9–53.4, n = 12), M. monticola (males 38.4–49.5, n = 17), M. periosa (males 71.3–93.8, n = 12), M. robusta (males 73.5–83.1, n = 6), M. longipes (male 47, n = 1; female 65, n = 1), M. oreocrypta (female 94.9, n = 1), M. serchhipii (male 37.1, n = 1), and M. takensis (males 47.3–53.0, n = 3).

By having relative larger body size (males 33.6–36.6, n = 5; females 40.6–42.8, n = 4; measurements in mm), Megophrys cf. pachyproctus differs from M. zunhebotoensis (male 30.0, n = 1; female 39.0, n = 1), M. rubrimera (males 26.7–30.5, n = 8), and M. angka (males 31.2–32.1, n = 2).

By tympanum present distinctly, Megophrys cf. pachyproctus differs from M. gigantica, M. nankiangensis, and M. shapingensis (vs. absent or concealed in the latter).

By vomerine ridge and teeth present, Megophrys cf. pachyproctus differs from M. wawuensis (vs. absent in the latter).

By maxillary teeth present, Megophrys cf. pachyproctus differs from M. elfina, M. gerti, M. hansi, M. koui, M. microstoma, and M. synoria (vs. absent in the latter).

By hind limbs long and head not wide and flat, Megophrys cf. pachyproctus differs from M. carinense, M. chuannanensis, M. feae, M. intermedia, and M. popei (vs. hind limbs short and head flat wide in the latter).

By lacking a single, wide and flat palpebral projection on the edge of the upper eyelid, Megophrys cf. pachyproctus differs from M. lancip, M. montana, M. parallela, M. baluensis, M. edwardinae, M. kobayashii, M. ligayae, M. nasuta, and M. kalimantanensis (vs. present in the latter).

By lacking rostral appendage, Megophrys cf. pachyproctus differs from M. stejnegeri (vs. having less rostral appendage in the latter).

By lacking a distinct horn-like tubercle at edge of upper eyelid, Megophrys cf. pachyproctus differs from M. dringi (vs. present in the latter).

By vomerine teeth present, Megophrys cf. pachyproctus differ from M. vegrandis, M. baolongensis, M. binchuanensis, M. binlingensis, M. boettgeri, M. brachykolos, M. cheni, M. kuatunensis, M. lini, M. lishuiensis, M. minor, M. obesa, M. palpebralespinosa, M. sangzhiensis, M. shuichengensis, M. spinata, M. tuberogranulata, M. wuliangshanensis, M. wushanensis, M. ombrophila, M. leishanensis, M. wugongensis, M. mufumontana, M. feii, M. auralensis, and M. huangshanensis, M. angka, M. shunhuangensis, M. jiangi, and M. xianjuensis (vs. absent in the latter).

By relatively finger lengths I < II < IV < III and nuptial pads present only on finger I, Megophrys cf. pachyproctus differs from M. nanlingensis (vs. relatively finger lengths II < I < IV < III, nuptial pads and nuptial spines invisible in males during breeding season in the latter).

By toes with rudimentary webbing, Megophrys cf. pachyproctus differs from M. serchhipii (vs. at least one fourth webbed in the latter).

By toes with narrow lateral fringes, Megophrys cf. pachyproctus differs from M. binchuanensis, M. cheni, M. jingdongensis, M. lini, M. rubrimera, M. shuichengensis, M. spinata, M. feii, M. vegrandis, and M. glandulosa (vs. wide in the latter).

By dorsal skin rough but without spines, Megophrys cf. pachyproctus differs from the following species: M. vegrandis (vs. smooth); M. medogensis (vs. smooth with small granules); M. daweimontis (vs. smooth); M. fansipanensis (vs. smooth with small granules); M. oropedion (vs. smooth with small granules); M. parva (vs. smooth); M. zhangi (vs. smooth); and M. jiulianensis (vs. dorsal skin rough with spines).

By snout rounded in dorsal view and nuptial pad only present only on finger I, Megophrys cf. pachyproctus differs from M. dongguanensis (vs. snout pointed, nuptial pads present on the first two fingers in the latter).

Megophrys cf. pachyproctus further differs from M. medogensis by the following characters: nuptial pads only present on finger I in males (vs. on the first two fingers in the latter); dorsal skin rough (vs. relatively smooth in the latter); vomerine ridge moderate, vomerine teeth weak (vs. both strong in the latter).

By having following characters of skull, Megophrys cf. pachyproctus differs from M. medogensis: skull weakly ossified, opening of anterior fontanelle present, sagittal suture distinctly open (vs. skull well ossified, opening of anterior fontanelle and sagittal suture occlusive in the latter); frontoparietal front equals rear (vs. distinctly wider in the latter); sphenethmoid rough with curves and pits, middle front edge protruding (vs. relatively smooth with few pits, truncate in the latter); exoccipitals posterior to the line connecting conjunctions of quadratojugal and mandible (vs. anterior in the latter); and columella auris short (vs. long in the latter).

By having following characters of bioacoustics, Megophrys cf. pachyproctus differs from M. medogensis (Tables 3, Suppl. material 1: Table S5): call duration significantly much longer (491–889 ms vs. 121–241 ms; P < 0.001); dominant frequency significantly higher (3.2–3.3kHz vs. 2.3–3.0 kHz; P < 0.01); and call intervals significantly longer (493–720 ms vs. 153–254 ms; P < 0.001).

Megophrys cf. pachyproctus very resemble M. pachyproctus on morphology, but differs from the latter in the following characters: protuberance beyond cloaca small, barely visible from ventral view, not swollen (vs. protuberance present on vent beyond cloaca large, swollen, arc-shaped, can be seen on both dorsal and lateral view in the latter); inner metatarsal tubercle distinct partially fused with toe I (vs. inner metatarsal tubercle separate from base of toe I at a distance nearly twice its diameter in the latter). Megophrys cf. pachyproctus further differs from M. pachyproctus by having the following characters on skull morphology: premaxillary and maxillary teeth weak, separated from others by gaps (vs. strong, closely positioned with others in the latter); inner edge of nasal bones half contact with sphenethmoid (vs. mostly in the latter); sphenethmoid rough with curves and pits, middle front edge protruding (vs. relatively smooth with few pits, truncate in the latter); and conjunction of parasphenoid anterior process meet with sphenethmoid narrow, width ca. half the constriction near its base (vs. moderate, ca. three quarters in the latter).

This group is currently known at elevation from 1560 m to 2003 m in Medog County, Tibet Autonomous Region, China. It inhabits mountain streams of subtropical forests. During June, males call on branches and leaves of bushes near mountain stream with a distance at least three meters from others, where covered with dense broad leaf forests (Figs 10C, D, H, I, Suppl. material 2: Fig. S5B, S5F). Females collected during October were gravid with well-developed eggs, and also found on leaves of floor vegetation like Elatostema species and ferns near small mountain streams. Distribution elevation overlap with M. medogensis at 1560 m, where a small stream pond was found to have tadpoles of three Megophrys species on 18 June, including M. medogensis (at stage 42), Megophrys cf. pachyproctus (at stages 26–27), and Megophrys yeae sp. nov. (at stages 28–35). Theloderma sp. and Amolops medogensis Li and Rao, 2005 were recorded at the same habitat.

(Figs 3D, I, N, S, X, 8). Adult male CIBMT171053, collected from vicinity of Renqingbeng Temple, Medog County, Tibet Autonomous Region, China (29.304832°N, 95.361682°E, 2003 m) by SC Shi on 26 October 2017.

(Suppl. material 2: Fig. S3). Two adult gravid females CIBMT171060 and CIBMT171062, collected along with the holotype.

The specific name is in honor of Professor Zhou Kai-Ya, for his contribution to Chinese amphibian research.

Zhou’s horned toad (English), Zhou Shi Jiao Chan (周氏角蟾, Chinese).

Megophrys zhoui sp. nov. is assigned to the genus Megophrys sensu lato based upon molecular phylogenetic analyses and the following morphological characters: canthus rostralis well-developed; supratympanic fold distinct; axillary glands small and tit-like, on sides of the breast; head length more than 25% of body size; upper jaw protruding beyond the margin of the lower jaw; no skin fold on back of head; maxillary teeth present; tympanum distinct; hind legs long and thin.

Megophrys zhoui sp. nov. is distinguished from its congeners by a combination of following characters: body small (male 23.0, n = 1; females 23.5–23.9, n = 2); vomerine ridge weak, vomerine teeth absent; tympanum present, moderate; base of finger I in similar size with finger II, relative finger lengths I < II < IV < III, fingertips not expanded into small pads; toes with narrow lateral fringes or absent; inner metatarsal tubercle long oval, positioned on base of toe I; dorsal skin relatively smooth; protuberance beyond cloaca indistinct, barely visible from ventral view, not swollen; skull weakly ossified, premaxillary and maxillary teeth weak; skull wider slightly than long; nasal bones not contact with sphenethmoid.

(Figs 3D, I, N, S, X, 8). Measurements in mm. Adult male, with well-developed testes; body slender, extremely small (SVL 23.0); protuberance beyond cloaca small, not visible from ventral view, not swollen.

Head moderate, longer than wide (HW 7.8, HL 8.3, IFE 4.5, IBE 7.2); snout near rounded in dorsal view, slightly protruding beyond lower jaw; rostral appendage absent (SL 3.6); canthus rostralis blunt; loreal region slightly concave, dorsal surface of snout slightly concave; nostril oval, closer to eye than tip of snout (SN 1.8, EN 1.4); distance between nostrils approximate distance between upper eyelids (IN 3.0, IUE 2.7); eyes twice size of tympanum (EL 2.7, TYD 1.3); pupils diamond, inferior angle slightly concave; eye-tympanum distance subequal with tympanum diameter (TYE 1.1); tympanum rounded, upper 1/3 conceal with supratympanic ridge; interorbital space flat, wider than upper eyelids (UEW 2.3); pineal ocellus not visible; two arcuate vomerine ridges present, orientation of two ridges acutely angled, not enlarged at posterior ends, shortest distance between two ridges equal to length of vomerine ridges; vomerine teeth absent; maxillary teeth present; tongue weakly notched behind, medial lingual process absent.

Forearm slender, not wider than upper arms, shorter than hand (FAL 5.2, HAL 7.1); fingers thin, without rudimentary webbing; subarticular tubercles absent; inner and outer metacarpal tubercles indistinct; base of finger I equal wide with base of finger II; finger relative length I < II < IV < III; tips of fingers slightly swollen, without pads (FIIIW 0.5).

Hindlimbs thin and long, tibio-tarsal articulation reaches middle eye; thighs shorter than shanks but longer than feet (TL 11.5, SHL 12.5, FOL10.9, TFOL 16.7); toes slender, relative length I < II < V < III < IV, rudimentary webbed, without lateral fringes, tips slightly swollen, no dermal ridges on ventral surface; subarticular tubercles absent; outer metatarsal tubercle absent; inner metatarsal tubercle long oval (IMT 1.1), positioned on base of toe I.

Dorsal surface of head and body basically smooth, with skin ridges formed by small disconnected granules; lateral surface of head smooth, tympanum ring not raised; two small granules on out edges of upper eyelid; supratympanic ridges nearly straight, extend from behind upper eyelids to above forearm insertions, rear part not thicker than the front; flanks smoother than dorsum, with several small tubercles one or two × size of nostril; skin on head scattered with tiny granules, some lager granules form a triangle between eyes; a “Y”-shaped skin ridges present between shoulders, but posterior part connected the middle of a “W”-shaped skin ridge on dorsum; several larger granules on rear dorsum behind the “W”; dorsal surface of arm smooth, scattered with tiny granules; dorsal hand and feet smooth; dorsal thighs and shanks smooth, with several larger granules; ventral surface of body and limbs smooth; pectoral glands tiny, barely visible, close to axilla on chest; pectoral glands small and rounded, slightly larger than fingertips; closer to outer edge of knee than to cloaca.

(Fig. 3D, I, N, S, X). Dorsal surface of body and limbs covered with dense gray pigments; larger granules on body and limbs light colored; a brown triangle present between eyes on head; markings on dorsum, and larger granules on dorsal thighs and shanks with brown fringes around; one broad brown transverse bands present on finger II, III and IV; two narrow transverse short bands present on lower arms; one or two faint brown transverse bands on dorsal toes. Lateral side of head pale gray mostly; skin on upper jaw between nostril and below eyes colored lighter; eyes dark with silver dense fiber around pupils and radiate on iris; supratympanic ridge light colored; chest, ventral surface of head, arms and shanks and feet covered with dense smoky gray pigments; abdomen ivory stained with smoky pigments, and scattered with several dark dots; several small ivory patches present on ventral margin of mandible; a darker brown patches with light colored inner edges extend from posterior end of jaws to ventral surface of upper arms on both sides; ventral surface hand mostly with smoky gray pigments, but base of finger I and II ivory; a brown stripe present on ventrolateral body; ventral surface of thighs smoky gray; tips of digits light colored; pectoral and femoral glands ivory.

(Fig. 8). Dorsal body and limbs orange-brown, granules on body orange-red; markings on dorsal body as described above; lateral head basically brown; supratympanic ridge orange; temporal region under supratympanic ridge dark brown; upper lips and canthus rostralis stained with orange; dark patches present on upper lips under eyes; iris orange-red, brighter around pupils. Flanks with several larger orange dots, ventrolateral trunk with white pigments and larger white dots. Throat, chest, arms orange-brown, mottled with dense white pigments; chin stained with orange, several small white patches present on lower lips; brown patches from posterior end of jaws to ventral surface of upper arms edged with white at inner side; upper abdomen orange-brown, stained with several faint orange dots; lower abdomen white, scattered with several clean orange dots; both lateral sides of abdomen with broad brown strips; ventral surface of thighs and shanks flesh brown, with several white tiny granules around cloaca; ventral hand with dense gray-brown pigments, base of finger I and II fleshy; inner and outer metacarpal tubercle, and tips of fingers light orange; ventral feet brown; inner metatarsal tubercle, tips of toes light orange.

Figure 8. 

The holotype adult male CIBMT171053 of Megophrys zhoui sp. nov. in life. A dorsolateral view of body B ventral view of body C dorsolateral view of head D ventral view of hand E ventral view of foot.

(Fig. 5D, J). Skull weakly ossified, width equal to length; maxillary overlapping with the quadratojugal; premaxillary and maxillary teeth weak, barely visible; teeth absent on mandible; vomerine ridge weak, vomerine teeth absent; nasal process of premaxilla protruding beyond skull; nasal bones separated from each other, completely disconnected with sphenethmoid; sphenethmoid relatively smooth with several small pits on dorsal surface and ventral surface, the front edge of sphenethmoid rounded and protruding forward, separated from premaxilla; frontoparietal partially divided by a narrowly opening sagittal suture; anterior fontanelle almost occlusive; front and rear part of frontoparietal almost equally wide; posterior edge of exoccipitals posterior to the line connecting conjunctions of quadratojugal and mandible; pterygoid moderate; anterior process of squamosal slender and sharp, tip in the middle of the distance from the base to the junction of pterygoid and quadratojugal, posterior process present; prootic relatively smooth, separated from exoccipitals; anterior process of parasphenoid in shape of narrow trapezoid, anterior part not raised above sphenethmoid, conjunction of anterior process of parasphenoid with width ca. two thirds of the constriction near the base; columella auris short.

(Suppl. material 2: Fig. S3). Paratypes resemble the holotype in general but with following differences: for CIBMT171060, narrow fringes present on toes, tympanum slightly larger than half eyes, orange granules on dorsum form an “X”-shaped skin ridge and a pair of nearly parallel ridges on dorsolateral trunk, and ventral surface less brown and more orange; for CIBMT171060, a broad “X” pattern present on dorsum, and parallel skin ridges on dorsolateral trunk do not make contact with skin ridges between the left parallel ridge.

Male with single subgular vocal sac; nuptial pad not observed in October; lineae musculinae absent.

The species is currently only discovered from type locality Renqingbeng Temple area at elevation 2003 m in Medog County, Tibet Autonomous Region, China, inhabits small streams in subtropical forests (Fig. 10D, J; Suppl. material 1: Table S5B). All three individuals were found on short herds or ferns beside small mountain stream at a distance shorter than 0.5 m to the ground (Fig. 10J). Females were found to be gravid during October, but eggs not well developed. Advertisement calls not head in October. Several gravid females of Megophrys cf. pachyproctus were collected from the same small stream with types of Megophrys zhoui sp. nov. on the same night. Theloderma sp. and Amolops nyingchiensis Jiang, Wang, Xie, Jiang, and Che, 2016 were recorded at the same habitat.

By body relatively smaller (male 23.0, n = 1; females 23.5–23.9, n = 2 measurements in mm), Megophrys zhoui sp. nov. differs from M. pachyproctus (males 35.3–35.7, n = 2; female 35.8, n = 1), Megophrys cf. pachyproctus (males 33.6–36.6, n = 5; females 40.6–42.8, n = 4), M. medogensis (males 57.2–68.7, n = 21), M. acuta (males 27.1–33.0, n = 10), M. baolongensis (males 41.8–45.0, n = 5), M. binchuanensis (males 32.0–36.0, n = 4), M. binlingensis (males 45.1–51.0, n = 3), M. boettgeri (males 34.5–37.8, n = 20), M. brachykolos (males 33.7–39.3, n = 5), M. caudoprocta (males 70.8–81.3, n = 4), M. cheni (males 26.2–29.5, n = 15), M. daweimontis (males 34–37, n = 18), M. fansipanensis (males 30.9–44.3, n = 13), M. hoanglienensis (males 37.4–47.6, n = 11), M. insularis (males 36.8–41.2, n = 5), M. jingdongensis (males 53.0–56.5, n = 3), M. jinggangensis (males 35.1–36.7, n = 2), M. kuatunensis (males 26.2–31.4, n = 18), M. liboensis (males 61.6–62.9, n = 4), M. lini (males 34.1–39.7, n = 20), M. lishuiensis (males 30.7–34.7, n = 13), M. minor (males 34.5–41.2, n = 4), M. obesa (male 35.6, n = 1; females 37.5–41.2, n = 6), M. omeimontis (males 56.0–59.5, n = 10), M. palpebralespinosa (male 36, n = 1; female 41, n = 1), M. rubrimera (males 26.7–30.5 n = 8), M. sangzhiensis (male 54.7, n = 1), M. shuichengensis (males 102.0–118.3, n = 7), M. spinata (males 47.2–54.4, n = 18), M. tuberogranulata (males 33.2–39.6, n = 9), M. wuliangshanensis (males 27.3–31.6, n = 10), M. wushanensis (males 30.4–35.5, n = 10), M. ombrophila (males 27.4–34.5, n = 5), M. leishanensis (males 32.1–42.3, n = 10), M. dongguanensis (males 30.2–39.3, n = 9), M. nankunensis (males 29.9–34.9, n = 11), M. jiulianensis (males 30.4–33.9, n = 9), M. nanlingensis (males 30.5–37.3, n = 10), M. wugongensis (males 31.0–34.1, n = 4), M. mufumontana (males 30.1–30.8, n = 2), M. feii (males 24.5–25.1, n = 4; female 28.2–28.9, n = 2), M. vegrandis (males 27.5–30.6, n = 4), M. aceras (males 55.8–62.4, n = 6); M. ancrae (males 39.1–45.3, n = 8), M. auralensis (males 76.7, n = 1), M. damrei (male 57.1, n = 1; female 69.1, n = 1), M. flavipunctata (males 56.9–68.4, n = 4), M. glandulosa (males 76.3–81.0, n = 10), M. himalayana (males 68.0–73.5, n = 6), M. huangshanensis (males 36.0–41.6, n = 4), M. katabhako (males 35.4–37.0, n = 3), M. lekaguli (males 55.6–66.6, n = 8), M. longipes (male 47, n = 1; female 65, n = 1), M. major (males 71.6–87.5, n = 12), M. mangshanensis (male 62.5, n = 1; female 73.0, n = 1), M. maosonensis (male 77, n = 1; female 94, n = 1), M. megacephala (males 45.9–53.4, n = 12), M. monticola (males 38.4–49.5, n = 17), M. periosa (males 71.3–93.8, n = 12), M. robusta (males 73.5–83.1, n = 6), M. longipes (male 47, n = 1; female 65, n = 1), M. oreocrypta (female 94.9, n = 1), M. oropedion (males 32.8–39.2, n = 7), M. parva (males 35.6–50.6, n = 5), M. periosa (males 71.3–93.8, n = 12), M. robusta (males 73.5–83.1, n = 6), M. sanu (males 39.0–46.7, n = 5), M. serchhipii (male 37.1, n = 1), M. takensis (males 47.3–53.0, n = 3), M. zhangi (males 32.5–37.2, n = 3), M. zunhebotoensis (male 30.0, n = 1; female 39.0, n = 1), M. angka (males31.2–32.1, n = 2), M. shunhuangensis (males 30.3–33.7, n = 10), M. jiangi (males 34.4–39.2, n = 9), and M. xianjuensis (males 31.0–36.3, n = 7).

By tympanum distinct moderate, larger than half eye diameter, Megophrys zhoui sp. nov. differs from M. gigantica, M. nankiangensis, M. shapingensis, and M. wawuensis (vs. tympanum absent, concealed or very small in the latter).

By maxillary teeth present, Megophrys zhoui sp. nov. differs from M. elfina, M. gerti, M. hansi, M. koui, M. microstoma, and M. synoria (vs. absent in the latter).

By hind limbs long and head not wide and flat, Megophrys zhoui sp. nov. differs from M. carinense, M. chuannanensis, M. feae, M. intermedia, and M. popei (vs. head wide flat and hind limbs short in the latter).

By lacking a single, wide and flat palpebral projection on the edge of the upper eyelid, Megophrys zhoui sp. nov. differs from M. lancip, M. montana, M. parallela, M. baluensis, M. edwardinae, M. kobayashii, M. ligayae, M. nasuta, and M. kalimantanensis (vs. present in the latter).

By lacking rostral appendage, Megophrys zhoui sp. nov. differs from M. stejnegeri (vs. having less rostral appendage in the latter).

By lacking a distinct horn-like tubercle at edge of upper eyelid, Megophrys zhoui sp. nov. differs from M. dringi (vs. present in the latter).

By vomerine ridge weak, Megophrys zhoui sp. nov. differs from M. pachyproctus, M. medogensis, and Megophrys cf. pachyproctus (vs. vomerine ridge stronger in the latter); differs from M. vegrandis, M. baolongensis, M. binchuanensis, M. boettgeri, M. kuatunensis, M. lishuiensis, M. wuliangshanensis, M. wushanensis, M. ombrophila, M. leishanensis, M. feii, M. huangshanensis, M. shunhuangensis, and M. jiangi (vs. absent in the latter).

By vomerine teeth absent, Megophrys zhoui sp. nov. differs from Megophrys cf. pachyproctus, M. pachyproctus, M. medogensis, M. caudoprocta, M. daweimontis, M. fansipanensis, M. hoanglienensis, M. insularis, M. jingdongensis, M. jinggangensis, M. liboensis, M. omeimontis, M. rubrimera, M. dongguanensis, M. nankunensis, M. jiulianensis, M. nanlingensis, M. aceras, M. ancrae, M. damrei, M. flavipunctata, M. glandulosa, M. himalayana, M. katabhako, M. lekaguli, M. longipes, M. major, M. mangshanensis, M. maosonensis, M. megacephala, M. monticola, M. oreocrypta, M. oropedion, M. parva, M. periosa, M. serchhipii, M. takensis, M. zhangi, and M. zunhebotoensis (vs. present in the latter).

By toes with narrow lateral fringes or absent, Megophrys zhoui sp. nov. differs from M. binchuanensis, M. cheni, M. jingdongensis, M. lini, M. rubrimera, M. shuichengensis, M. spinata, M. feii, M. vegrandis, and M. glandulosa (vs. wide in the latter).

By dorsal skin relatively smooth, Megophrys zhoui sp. nov. differs from M. pachyproctus, Megophrys cf. pachyproctus, M. insularis, M. jinggangensis, M. tuberogranulata, M. wuliangshanensis, M. leishanensis, M. dongguanensis, M. jiulianensis, M. nanlingensis, M. wugongensis, M. mufumontana, and M. feii (vs. rough in the latter).

By tympanum moderate (TYD/EL 0.40–0.60, n = 9), Megophrys zhoui sp. nov. differs from species with large tympanum: M. brachykolos (0.70–0.75, n = 7); M. jinggangensis (0.73–0.88, n = 5), and M. takensis (0.71–0.77, n = 4).

By fingertips not expanded into small pads, Megophrys zhoui sp. nov. differs from M. vegrandis, M. ancrae, and M. feii (vs. fingertips with small pads in the latter).

By the following characters, Megophrys zhoui sp. nov. differs from M. pachyproctus: protuberance beyond cloaca small, not visible from ventral view, not swollen (vs. protuberance present on vent beyond cloaca large, swollen, arc-shaped, visible on both dorsal and lateral view in the latter); and inner metatarsal tubercle long oval, positioned on base of toe I (vs. inner metatarsal tubercle rounded, separate from base of toe I at a distance nearly twice its diameter in the latter).

By having following differences on skull morphology, Megophrys zhoui sp. nov. differs from M. pachyproctus: premaxillary and maxillary teeth weak, barely visible or separated from others by gaps (vs. strong, closely positioned with others in the latter); nasal bones not contact with sphenethmoid (vs. mostly in the latter); and middle front edge of sphenethmoid protruding (vs. truncate in the latter).

By base of finger I in similar size with finger II, relative finger lengths I < II < IV < III, Megophrys zhoui sp. nov. differs from M. medogensis (vs. base of finger I distinctly larger than finger II, relative finger lengths II < I < IV < III in the latter).

By having following differences on skull, Megophrys zhoui sp. nov. differs from M. medogensis: skull weakly ossified, opening of anterior fontanelle present, sagittal suture narrowly or wide open (vs. skull well ossified, opening of anterior fontanelle and sagittal suture occlusive in the latter); premaxillary and maxillary teeth weak, barely visible or separated from others by gaps (vs. strong, closely positioned with others in the latter); frontoparietal front equals rear (vs. distinctly wider in the latter); exoccipitals posterior to the line connecting conjunctions of quadratojugal and mandible (vs. anterior); and columella auris short (vs. long in the latter).

By base of finger I similar in size with finger II, nasal bones not in contact with sphenethmoid, and texture of sphenethmoid relatively smooth with several small pits, Megophrys zhoui sp. nov. differs from Megophrys cf. pachyproctus (vs. base of finger I larger than the base of finger II, nasal bones mostly contact with sphenethmoid, and sphenethmoid rough with curves and pits in the latter).