Rana megatympanum, BAIN & LATHROP & MURPHY & ORLOV & CUC, 2003

BAIN, RAOUL H., LATHROP, AMY, MURPHY, ROBERT W., ORLOV, NIKOLAI L. & CUC, HO THU, 2003, Cryptic Species of a Cascade Frog from Southeast Asia: Taxonomic Revisions and Descriptions of Six New Species, American Museum Novitates 3417, pp. 1-60 : 50-53

Rana megatympanum , new species

(Previously referred to as species 7, ‘‘Large’’) Figures 12O, P , 13G , 14G, H

HOLOTYPE: (ROM field no. 12999) ROM 39684, a gravid adult female from Khe Moi River , approximately 24 km west of Con Cuong village (by road), Con Cuong District, Nghe An Province, Vietnam (18°56̍30̎N, 104°48̍35̎E) found between 24 and 29 October 1994 by I.S. Darevsky, L.A. Lowcock, R.W. Murphy, and N.L. Orlov. The holotype had leg and liver tissue removed shortly after it was euthanised.

PARATYPES: Eight females (ROM 39263, 39685–39691) collected with holotype between 24 and 29 October 1994 by I.S. Darevsky, L.A. Lowcock, R.W. Murphy, and N.L. Orlov. Four males (ROM 39237–39240) from Na Hang Nature Reserve, Tuyen Quang Province, Vietnam (22°21̍54̎N, 105°25̍40̎E) found along waterfalls between 26 and 27 May 1996 by A. Lathrop and R.W. Murphy between 193 and 0200 hours. ROM 26398– 26400 Con Cuong District, Nghe An Province, Vietnam (18°56̍30̎N, 104°48̍35̎E), collected 5 June 1995 by B. Hubley, A. Lathrop, R.W. Murphy, and N.L. Orlov .

DIAGNOSIS: Rana megatympanum , a member of the subgenus Odorrana (sensu Fei et al., 1990), is characterized by a combination of the following attributes: (1) body dorsoventrally compressed; (2) SVL means of males 52 mm (48–55 mm), females 100 mm (93–105 mm); (3) vomerine teeth in rows oblique to choanae; (4) yellow lip­stripe present in males, absent or indistinct in females; (5) head broad, bluntly rounded in profile; (6) tympanum round, distinct, TMP:EYE in males enormous (1.20), greater than in females (0.51); (7) supratympanic fold weak; (8) dorsal skin shagreened, dorsolateral folds present only in males; (9) dorsum olive to brown sometimes with black spots; flanks marbled yellow and brown­gray; forelimbs and hindlimbs barred; (10) ventromedial callous pad on fingers II, III, and IV to proximal tubercle, fringes on fingers II, III, and IV; (11) disks on fingers and toes greatly enlarged (>2× base of phalanges); (12) feet fully webbed to toe disk, lateral fringes on I and V to terminal phalanges, webbing brown; (13) subarticular tubercles and an internal metatarsal tubercle distinct, conical; (14) terminal phalanges T­ shaped; (15) xiphisternum large, deeply notched posteriorly; (16) males with nuptial pads, paired gular pouches, pectoral spines absent; (17) eggs white.

COMPARISONS: Rana megatympanum superficially resembles other Asian cascade ranids, including Huia nasica , Rana andersonii , R. archotaphus , R. bacboensis , R. banaorum , R. chalconota , R. chloronota , R. daorum , R. grahami , R. graminea , R. hainanensis , R. hejiangensis , R. hmongorum , R. hosii , R. morafkai , R. jingdongensis , R. junlianensis , R. kwangwuensis , R. leporipes , R. livida , R. margaretae , R. schmackeri , R. sinica , and R. tiannensis (table 12). It can be differentiated from all other Odorrana by the enormous sexual dimorphism in tympanum size (TMP:EYE 1.20 in males, 0.51 in females). Male R. megatympanum have a yellow lip­stripe and females have an indistinct or absent yellow lip­stripe, differentiating it from H. nasica , R. archotaphus , R. banaorum , R. chalconota , R. chloronota , R. daorum , R. graminea , R. hejiangensis , R. hosii , R. morafkai , R. leporipes , and R. livida (all with white lip­stripes); R. andersonii , R. bacboensis , R. hainanensis , R. jingdongensis , R. margaretae , and R. tiannensis have vertical lip­bars; R. junlianensis has a yellow lipstripe with brown lip­bars; R. schmackeri has no lip­stripe or vertical lip­bars. The broad, rounded snout differentiates R. megatympanum from H. nasica , R. andersonii , R. chalconota , and R. schmackeri (obtusely pointed) and from R. graminea and R. margaretae (depressed). Its gular pouches distinguish R. megatympanum from R. andersonii , R. chalconota , R. grahami , R. hainanensis , R. hmongorum , R. hosii , R. jingdongensis , R. junlianensis , R. kwangwuensis , and R. margaretae . Dorsolateral folds immediately differentiate male R. megatympanum from R. andersonii , R. bacboensis , R. chloronota , R. hainanensis , R. hejiangensis , R. morafkai , R. jingdongensis , R. junlianensis , R. kwangwuensis , R. livida , R. schmackeri , R. sinica , and R. tiannensis . The dorsolateral fold of male R. megatympanum differs from that of R. daorum , which is composed of minute white granules, R. hmongorum and R. grahami , whose dorsolateral pustules sometimes form a dorsolateral fold, and R. banaorum and R. chalconota , which have folds that are distinct and continuous, extending to the groin. The olive brown coloration with black spots of R. megatympanum differentiates it from H. nasica (olive­brown dorsum, lighter brown laterally) and from R. archotaphus , R. chalconota , R. chloronota , R. daorum , R. graminea , R. hejiangensis , R. hmongorum , R. hosii , R. jingdongensis , R. junlianensis , R. kwangwuensis , R. leporipes , R. margaretae , R. schmackeri , R. sinica (all with green). Rana megatympanum lacks an external metatarsal tubercle present in R. archotaphus and R. chalconota . Absence of ventral spines in male R. megatympanum separates them from R. andersonii , R. grahami , R. jingdongensis , R. junlianensis , R. margaretae , and R. schmackeri . The presence of white eggs differentiates R. megatympanum from H. nasica , R. andersonii , R. chalconota , R. grahami , R. junlianensis , R. margaretae , R. schmackeri (white eggs with melanic poles), and R. bacboensis (eggs completely melanic). Rana megatympanum differs from R. sinica by its distinct, uncovered tympanum (indistinct and covered with a layer of skin in R. sinica ), its disk size (small in R. sinica ), its relative finger lengths (I <II <IV for R. sinica, II <I <IV for R. megatympanum ), and its T­ shaped distal phalanges (rounded in R. sinica ). Rana megatympanum can be distinguished from R. leporipes by its webbing (only to the basal end of the distal phalanx in R. leporipes , to the disk in R. megatympanum ), supratympanic fold (colored white in R. leporipes ), and its T­ shaped distal phalanges (oblong, somewhat rounded in R. leopripes ). Rana megatypmanum also differs from R. hejiangensis by its finger formula (II <I <III <IV for R. hejiangensis ), and by its large disks (small for R. hejiangensis ). Rana megatympanum closely resembles R. andersonii , R. hainanensis , R. jingdongensis , and R. tiannensis . In addition, R. megatympanum differs from R. andersonii in that its males are smaller (53–78 mm for males of R. andersonii ), and its finger and toe­disks are relatively larger. Rana megatympanum differs from R. hainanensis in its smaller SVL ( R. hainanensis males 49–62 mm, females 75–122 mm, R. megatympanum males 48–55 mm, females 93–105 mm) and its relative finger lengths (II <IV <I <III for R. hainanensis, II <I <IV <III for R. megatympanum ). Rana megatympanum further differs from R. jingdongensis by its smaller males ( R. jingdongensis SVL 62–81 mm) and skin ( R. jingdongensis dorsum scattered with tubercles and large warts, lips and sides of heads with white spines, all absent in R. megatympanum ). Rana megatympanum most closely resembles R. tiannensis , another large brown cascade ranid, but differs from it by having shagreened dorsal skin with small lateral granulations (dorsum of R. tiannensis is rough with large, prominent lateral granulations), and toe disks are smaller than those on fingers (the opposite condition of R. tiannensis ).

DESCRIPTION OF HOLOTYPE: ROM 39684, a gravid female, head width 77% of head length, length 50% of SVL; snout short, acutely rounded in dorsal view, bluntly rounded in profile, protruding beyond margin of lower jaw; eye very large, prominent, 73% of snout length; eyelid broader than interorbital distance. Top of head flat; canthus rostralis rounded; loreal region concave; lip flared just anterior to orbit; nostril about three­fourths distance from eye to tip of snout; supratympanic fold curving posteroventrally from posterior corner of eye to a level above the insertion of arm; tympanum round, distinctly visible, separated from eye by distance equal to TMP, 52% of EYE. Choanae ovoid; vomerine dentigerous processes prominent, oblique, posteromedial to choanae, each bearing numerous teeth. Tongue cordiform, distinctly notched posteriorly, free for approximately two­thirds its length.

Forearms moderately robust; fingers moderately short, slender, hands 27% of SVL, relative lengths of fingers II <I <IV <III, lateral fringes on finger II, III, and IV, with median callous pads to proximal tubercle; disks greatly expanded (>2× base of phalanges), relative pad size II <I <IV <III, pad width (III) 87% of pad length, ventral circummarginal grooves present; terminal phalanges T­ shaped; subarticular tubercles conical. Hindlimbs moderately robust; tibia length 69% of SVL; foot length 53% of SVL; relative toe lengths I <II <III <V <IV; inner tarsal fold absent; feet fully webbed to base of toe pads, lateral fringes on I and V to terminal phalanges; toes long, slender, with large, rounded triangular disks, relative pad size I = II = III> IV k V, pad width (IV) 75% of pad length, each with ventral circummarginal grooves; subarticular tubercles prominent and conical; inner metatarsal tubercle ovoid, long; outer metatarsal tubercle absent.

Xiphisternum large, deeply notched posteriorly.

Skin on dorsum shagreened, becoming increasingly granular laterally; dorsolateral folds absent; small tubercles posteroventral to tympanum; prominent granules on flanks and around cloaca; cloacal opening unmodified, directed posteriorly, at upper level of thighs.

COLOR IN LIFE (in preservative): Dorsum olive­brown, flanks yellow and brown­gray (gray to olive); lip­stripe absent (tympanum beige with dark brown center ring); loreal brown (black); iris gold; top one­third red, dorsal limbs brown with black banding (brown); posterior surface of thighs brown with black marbling (cloacal region black, thighs gray with white mottling); webbing marbled white on dark brown (brown on white); venter creamy white (creamy yellow with black mottling).

SECONDARY SEXUAL CHARACTERS: The eggs of the holotype are creamy white and 2 mm in diameter. Adult females have SVL approximately twice that of males. Males have a yellow lip­stripe, and females either lack one or have an indistinctly yellow lip. Males also possess a weak dorsolateral fold, whereas females do not. Males have a larger tympanum than females, velvety nuptial pads extending across the thumb, paired gular pouches located at the angle of the jaw, and no pectoral spines.

MEASUREMENTS OF HOLOTYPE (in mm): SVL 93.6; SNT 15.0; HDL 46.5; HDW 35.7; EYE 10.8; IOD 6.8; TMP 5.6; TEY 4.1; HND 25.7; FGR 19.6; FPL 3.0; FPW 2.6; TIB 65.0; FTL 49.7; TPL 3.2; TPW 2.4.

VARIATION OF PARATYPES: Variation in all type material is given in table 15.

MEASUREMENTS OF FEMALE PARATYPES (in mm, n = 10, ROM 26398–26400, 39685– 39691): SVL 100.3 ± 4.2 (93.6–105.3); SNT 14.8 ± 0.8 (13.8–16.5); HDL 45.1 ± 3.3 (41.3–47.6); HDW 35.2 ± 0.7 (34.1–35.7); EYE 10.2 ± 0.7 (9.3–11.6); IOD 8.8 ± 1.0 (6.8–10.0); TMP 5.3 ± 0.4 (4.6–5.9); TEY 4.7 ± 0.3 (4.1–5.0); HND 25.2 ± 2.5 (20.6– 29.7); FGR 21.0 ± 1.0 (19.6–22.6); FPL 3.5 ± 0.6 (2.8–4.4); FPW 3.0 ± 0.5 (2.5–3.8); TIB 63.0 ± 3.3 (55.8–67.7); FTL 72.0 ± 12.1 (49.7–88.0) TPL 3.4 ± 1.0 (1.9–5.2); TPW 2.8 ± 0.4 (2.2–3.4).

MEASUREMENTS OF MALE PARATYPES (in mm, n = 4, ROM 39237–39240): SVL 52.3 ± 3.4 (48.6–55.2); SNT 8.7 ± 0.8 (8.3–9.6); HDL 28.0 ± 1.4 (24.6–27.1); HDW 18.5 ± 0.8 (18.0–19.1); EYE 4.1 ± 0.9 (3.17–4.6); IOD 5.0 ± 0.5 (4.7–5.6); TMP 4.7 ± 0.3 (4.3–5.1); TEY 1.7 ± 0.3 (1.5–2.0); HND 15.2 ± 0.4 (14.8–15.5); FGR 12.5 ± 0.4 (12.2–13.0); FPL 2.0 ± 0.5 (1.6–2.5); FPW 1.9 ± 0.4 (1.4–2.3); TIB 32.7 ± 0.4 (32.3– 33.1); FTL 38.3 ± 7.3 (29.9–42.8) TPL 1.8 ± 0.6 (1.3–2.5); TPW 1.6 ± 0.1 (1.5–1.6).

ETYMOLOGY: The specific name is a noun in opposition, derived from the Latin prefix ‘‘mega’’ (meaning very large) and ‘‘tympanum’’, in reference to the relatively large tympanum of this species.

DISTRIBUTION AND ECOLOGY: Rana megatympanum is known from northern and north­central Vietnam. It occurs in montane rivers that vary from shallow and slow moving to torrential and deep. It may be found on boulders and logs, both in and around the water as well as in the adjacent forest. Radiographs revealed that large invertebrates (both insects and crustaceans) form part of the diet. Vocalizations and tadpoles are unknown.

REMARKS: The dorsolateral fold and very large tympanum of male R. megatympanum potentially make it Bourret’s (1942) ‘‘northern form’’ of R. chloronota (= R. graminea ). However, R. graminea is bright green above ( Boulenger, 1899) in contrast to the olivebrown dorsum of R. megatympanum .

Figures

Fig. 12. Heads of members of the Rana chloronota complex in lateral and dorsal views: (A, B) Rana chloronota, male (ROM 26402), and (C, D) female (ROM 26406); paratypes of (E, F) Rana bacboensis, new species (ROM 29529); (G, H) Rana daorum, new species (ROM 38538); (I, J) Rana hmongorum, new species (ROM 39891); (K, L) Rana morafkai, new species (ROM 39906); (M, N) Rana banaorum, new species (ROM39941); and (O, P) Rana megatympanum, new species (ROM 26398).

Fig. 13. Hands and feet of members of the Rana chloronota complex: (A) Rana chloronota (ROM 26402); paratypes of (B) Rana bacboensis, new species (ROM 29529); (C) Rana daorum, new species (ROM 38538); (D) Rana hmongorum, new species (ROM 26379); (E) Rana morafkai, new species (ROM 39906); (F) Rana banaorum, new species (ROM 39941); and (G) Rana megatympanum, new species (ROM 26398). Scale equals 5 mm.

Fig. 14. Members of the Rana chloronota complex from Vietnam. A. Paratype of R. hmongorum, new species, male from Lao Cai Province. (B) Female, brown (night) phase, (C) female, green (day) phase, and (D) male of R. morafkai, new species, from Gia Lai Province. (E) Female and (F) male of R. banaorum, new species, from Gia Lai Province. (G, H) female of R. megatympanum new species.