Theloderma lateriticum, Bain, Raoul H., Nguyen, Truong Q. & Doan, Kien V., 2009

Bain, Raoul H., Nguyen, Truong Q. & Doan, Kien V., 2009, A new species of the genus Theloderma Tschudi, 1838 (Anura: Rhacophoridae) from Northwestern Vietnam, Zootaxa 2191, pp. 58-68 : 60-65

Theloderma lateriticum sp. nov.

Figs. 2 , 3

Holotype: AMNH 168757/ IEBR A. 0860, adult male, Vietnam, Lao Cai Province, Van Ban District, Nam Tha Commune, above the Nam Tha river in disturbed, submontane semi-evergreen forest near 21° 54' 56" N, 104° 21' 39" E, between 1300–1400 m elevation, 10 September 2004, Raoul H. Bain, Nguyen Quang Truong, Lu A Cho & Trieu Tai Vuong. The holotype has an incision in the left leg from tissue samplings of muscle.

Diagnosis: Theloderma lateriticum sp. nov. is distinguishable from all other rhacophorid species from South China, Northeast India, and mainland Southeast Asia (north of the Isthmus of Kra) by a combination of: male SVL 23.5 mm; tympanum distinct, with distinct tympanic annulus; vomerine teeth absent; hand webbing absent; foot webbing reduced (Toe I, below proximal subarticular tubercle on postaxial side; Toe II, to level of proximal subarticular tubercle on postaxial side; Toe III below proximal subarticular tubercle on preaxial side, and just beyond proximal subarticular tubercle on postaxial side; Toe IV, to level of proximal subarticular tubercle on preaxial side, and just beyond proximal subarticular tubercle on postaxial side; and Toe V, just beyond proximal subarticular tubercle on preaxial side); outer metatarsal tubercle present; dorsal skin granular, bearing keratinized spicules, raised on small, isolated bumps; dermal fringes on the post axial portions of the limbs absent; dorsum, iris brick-red; mid-dorsal spot black; lip with small white spots; nuptial pad on Finger I; vocal sacs absent.

Description of holotype: AMNH 168757/IEBR A. 0860, adult male, habitus slender; head narrow, longer than wide; snout subacuminate in dorsal view, rounded in lateral aspect, projecting beyond lower jaw; nostril lateral, nearer to tip of snout than eye; canthus rostralis distinct, but not raised, distinct sulcus between nares; lores slightly concave, almost vertical, oblique; eye diameter 67% of snout length; pupil horizontally oval; interorbital distance greater than width of upper eyelid; pineal body not visible; tympanum distinct, round, covered by layer of skin, 74% of eye diameter, not depressed relative to skin of temporal region, tympanic annulus thin; vomerine teeth absent; choanae at extreme lateral edge; tongue elongated-cordiform, deeply notched posteriorly, free for approximately two-thirds its length; vocal sacs absent.

Tips of all four fingers expanded into round discs; circummarginal and transverse grooves appear as one continuous circular groove; width of Finger I disc smallest, width of Finger III disc about 1.5 times width of phalanx, 67% diameter of tympanum; relative Finger lengths I <II <IV <III, distal portion of IV reaches just proximal to disc of III; finger webbing absent; movable flaps of skin on preaxial side of Fingers II, III; one subarticular tubercle on Fingers I and II, two subarticular tubercles on III and IV, all conical and projecting; one supernumerary tubercle proximal to proximal subarticular tubercle on Fingers II, III, and IV; two palmar tubercles present; forearm robust; velvety nuptial pad on Finger I, on dorsal and medial surfaces to level proximal to subarticular tubercle.

Tips of toes expanded into rounded discs, smaller than width of fingers; circummarginal and transverse grooves appear as one continuous circular groove; relative Toe lengths I <II <III <V <IV; web below proximal subarticular tubercle on Toe I, and preaxial side of II, III; web reaches level of proximal subarticular tubercle on postaxial side of Toe II, preaxial side of IV; web reaches just beyond proximal subarticular tubercle on postaxial side of Toe III, IV, and preaxial side of V; fringes of web on preaxial side of Toe I and postaxial side of V to base of metatarsals; two outer metatarsals united, not separated by groove or web; subarticular tubercles low and round, one on Toes I and II, two on Toes II and V, three on Toe IV; inner metatarsal tubercle elongate, oval, and low, with fleshy protuberance on preaxial and medial surfaces; outer metatarsal tubercle low, indistinct.

Dorsal skin granular, bearing keratinized spicules on small, isolated bumps; keratinized spicules on small, isolated bumps also present on posterior portion of thigh around cloaca and preaxial surfaces of limb, but absent from lips, loreal region, and tympanum; supratympanic fold indistinct, curves from posterior edge of eye anterior to arm insertion, thickening considerably posterior to tympanum; rictal glands absent; postaxial line of tubercles on the limbs saw-tooth-like, not pronounced; tarsal fold absent; throat smooth, becoming coarsely tubercular towards belly.

Measurements (mm) of holotype: SVL 23.5; HDL 9.5; HDW 7.9; SNT 3.8; IND: 2.3; EYE 2.6; IOD 2.8; TMP 1.9; TEY 0.5; HND 7.2; F3DSC: 1.3; F4DSC 1.0; TIB 12.7; FEM 10.6; FTL 9.6.

Color in life: Dorsum, snout, loreal region, upper lip, upper eyelids, supratympanic fold, and all accompanying tubercles with deep brick-red wash overtop dark black-green; lips with small white spots; black mid-dorsal spot; dorsal wash fades to black-green patch on the sacral area; iris deep brick-red; tympanum black with bright white dots in the middle; upper portion of flanks deep brick-red with black blotches, including one large blotch in communication with tympanum and the largest in the sacro-inguinal region; lower half of flank with bright white spots interspersed among row-like black blotches; limbs barred black on red-brown to hands, feet; digit tips black with white spots; tubercles on limbs bright white to digit tips; venter uniform grey-brown with bright white spots, most dense on chest and belly.

Color in preservative: Dorsum, snout, loreal region, upper lip, upper eyelids, supratympanic fold, with light grey sheen over light brown spot on mid portion of head and dark grey elsewhere; lips, tympanum redbrown with dull white spotting; black mid-dorsal spot clearly visible as in life; flank light brown with black blotches clearly visible as in life; sacral area dark grey, with two dark dorsolateral black lines; limbs barred black with red-brown; digit tips grey; anterior portion of thigh mottled light brown with light grey; posterior portion of thigh light grey with light brown dusting; all dorsal tubercles white; throat, ventral portions of limbs as in color in life; chest with white spots around dark brown curved lines; each ‘grain’ of granular belly uniquely colored white brown or grey to form a patchwork; ventral portion of hands light grey; ventromarginal grooves of toes light grey.

Habitat and ecology: This specimen was collected from inside a bamboo hollow from a disturbed, submontane, evergreen forest. The locality is close to a cardamom farm within a bamboo forest that is inundated with small streams and seeps. The temperature had reached a daytime high of 31o C, and a nighttime low of 19o C. It was breezy. Also present inside bamboo of the same area were specimens of Theloderma asperum (adults and egg clutches), Kurixalus odontotarsus , and the snake Rhadinophis prasinus . Because of its locality in far northwestern Vietnam, this species may also occur in neighboring southeastern Yunnan Province, China, and northeastern Laos.

Etymology: The Latin adjective lateriticum means ‘of bricks’, referring to the brick-red color of the dorsum

Comparisons: The generic assignment of many small rhacophorid frog species from Asia is still uncertain (e.g. Bossuyt & Dubois 2001; Wilkinson et al. 2002; Frost et al. 2006; Grismer et al. 2007; Li et al. 2008; Fei et al., 2009). For this reason, we compare the new species with all species of Theloderma , and all rhacophorids from Northeast India, South China (including Hainan Island), and mainland Southeast Asia (north of the Isthmus of Kra) whose adult males have SVL less than 35 mm, lack hand webbing, lack dermal fringes on the post axial portions of the limbs, lack green coloration, and lack dorsal stripes: i.e., Theloderma asperum ; T. bicolor ; T. corticale ; T. gordoni ; T. horridum ; T. kwangsiense ; T. leporosum ; T. licin ; T. moloch ; T. nagalandense ; T. phrynoderma ; T. rhododiscus ; T. ryabovi ; T. stellatum ; Chiromantis laevis ; Nyctixalus pictus ; Philautus abditus ; P. andersoni ; P. aurifasciatus ; P. cardamonus ; P. cinerascens ; P. garo ; P. hainanus ; P. jinxiuensis ; P. k e m p i a e; P. k e m p i i; P. longchuanensis ; P. maosonensis ; P. m e n g l a e n s i s; P. ocellatus ; P. parvulus ; P. petilus ; P. shillongensis ; P. truongsonensis ; P. tytthus .

Theloderma lateriticum sp. nov. can be immediately distinguished from all known species of Theloderma by its brick-red dorsal wash ( T. asperum , T. rhododiscus , and T. ryabovi dominated by black and white; T. bicolor , T. corticale , and T. kwangsiense dominated by green and brown; T. gordoni , T. horridum , T. leporosum dominated by brown; T. licin solid white in the day, mottled with brown at night and in captivity; T. nagalandense dominated by large, orange-red patches; T. moloch , T. phrynoderma dominated by grey; and T. stellatum dominated by brown or lavender-grey), and minimal foot webbing: Toe I, below proximal subarticular tubercle on postaxial side (versus at least to subarticular tubercle); Toe II, to level of proximal subarticular tubercle on postaxial side (versus at least beyond subarticular tubercle); Toe III below proximal subarticular tubercle on preaxial side, and just beyond proximal subarticular tubercle on postaxial side (versus at least beyond subarticular tubercle on preaxial side, and at least to distal subarticular tubercle on postaxial side); Toe IV, to level of proximal subarticular tubercle on preaxial side, and just beyond proximal subarticular tubercle on postaxial side (versus at least to medial subarticular tubercle on preaxial side of IV, and at least to distal subarticular tubercle on postaxial side); and Toe V, just beyond proximal subarticular tubercle on preaxial side (versus at least to distal subarticular tubercle).

Theloderma lateriticum sp. nov. (SVL 23.5 mm) can further be distinguished from large congeners T. bicolor , T. corticale , T. gordoni , T. horridum , T. kwangsiense , T. leporosa , T. moloch , T. nagalandense , T. phrynoderma , and T. ryabovi (adult male SVL 40 mm or greater), by its distinct tympanic annulus (absent in all large congeners), and its granular dorsum (heavily rugose in all large congeners, except T. ryabovi ). In addition, T. ryabovi and T. horridum males possess vocal sacs (absent in T. lateriticum ).

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There are four small species of Theloderma (adult male SVL 29–35 mm, T. asperum ; 28, 30 mm, T. licin ; 26, 27 mm, T. rhododiscus ; and 27–35 mm, T. stellatum ). Theloderma lateriticum sp. nov. further differs from T. asperum with its line of tubercles on post axial portions of the limb (absent in T. asperum ), and absence of vocal sacs in males (present in males of T. asperum ). Theloderma lateriticum sp. nov. further differs from T. rhododiscus by having a granular dorsum with small, isolated bumps (rough, with network of longitudinal pointy ridges in T. rhododiscus ), one black mid-dorsal spot (several large dorsal spots in T. rhododiscus ), and grey ventral digital surfaces (orange-red in T. rhododiscus ). Theloderma lateriticum sp. nov. further differs from T. stellatum with its free hands (fingers one-third webbed in T. stellatum ), finger discs smaller than tympanum diameter (at least as large as tympanum in T. stellatum ), snout spotted white (spotted black in T. stellatum ).

Theloderma lateriticum sp. nov. most closely resembles the brown form of T. licin , but in addition to the above, further differs in the absence of finger webbing (present in T. licin ), the presence of a nuptial pad on Finger I (present on Finger II in T. licin ), the presence of tubercles on the supratympanic fold (absent in T. licin ), and the absence of vocal sacs in males (present in males of T. licin ).

The brick-red dorsum also differentiates Theloderma lateriticum sp. nov. from other regional rhacophorids that have male SVL less than 35 mm, lack hand webbing, lack dermal fringes on the post axial portions of the limbs, lack green coloration, and lack dorsal stripes: white with red vermiculations in C. laevis ; dark and/or cinnamon brown in N. pictus ; olive, grey, or brown in P. abditus , P. andersoni , P. cardamonus , P. cinerascens , P. g a ro, P. j i n x i u e n s i s, P. k e m p i a e, P. k e m p i i, P. longchuanensis , P. maosonensis , P. menglaensis , P. ocellatus , P. parvulus , P. shillongensis , P. tytthus ; dorsolateral portions soft yellow-beige in P. petilus ; yellow-gold with dark brown dorsolateral edges in P. truongsonensis ; and variable but never red in P. aurifasciatus . Theloderma lateriticum sp. nov. can be further differentiated from these rhacophorids by a combination of the following: snout length longer than eye diameter (opposite condition in N. pictus , P. abditus , P. cinerascens , P. garo , P. kempiae , P. parvulus ); absence of vomerine teeth (present in N. pictus , P. petilus ); absence of vocal sacs (present in Philautus abditus , P. aurifasciatus , P. cardamonus , P. hainanus , P. maosonensis , P. menglaensis ; P. ocellatus , P. parvulus , P. petilus ); distinct tympanum (completely hidden in P. abditus , P. kempiae , P. m a o s o n e n s i s; partially obscured in P. aurifasciatus , P. parvulus , P. tytthus ), an outer metatarsal tubercle (absent in C. laevis , P. abditus , P. cardamonus , P. hainanus , P. k e m p i i, P. longchuanensis , and P. t y t t h u s); upper surfaces with keratinized spicules (absent in C. laevis , Philautus abditus , P. cardamonus , P. g a ro, P. jinxiuensis , P. longchuanensis , P. truongsonensis ); postaxial limb tubercles (absent in P. petilus , N. pictus ), and solid dorsal wash (with interorbital sash, dorsal butterfly, ‘)(’, or X marking in Philautus abditus , P. andersoni , P. cardamonus , P. c i n e r a s c e n s, P. garo , P. jinxiuensis , P. k e m p i a e, P. maosonensis , P. menglaensis , P. parvulus , P. shillongensis , P. tytthus ; snout a different shade than rest of dorsum in P. kempii , P. shillongensis ).

Theloderma lateriticum sp. nov. further differs from N. pictus by its supratympanic fold (absent in N. pictus ); banded limbs (unbanded in N. pictus ); and venter with spots (immaculate in N. pictus ). Theloderma lateriticum sp. nov. further differs from P. andersoni by its reduced foot webbing (for T. lateriticum sp. nov. web below proximal subarticular tubercle on Toe I, preaxial sides of II, III [at or beyond level of proximal subarticular tubercle in P. andersoni ]; web to level of proximal subarticular tubercle on postaxial side of Toe II, preaxial side of IV, and just beyond proximal subarticular tubercle on postaxial side of Toe III, IV, preaxial side of V [well beyond level of proximal subarticular tubercle in P. andersoni ]); its banded limbs (not banded in P. andersoni ); and its grey-brown venter (yellow in P. andersoni ). Theloderma lateriticum sp. nov. further differs from P. aurifasciatus by its reduced foot webbing (for T. lateriticum sp. nov. web below proximal subarticular tubercle on Toe I, preaxial side of II [at level of proximal subarticular tubercle in P. aurifasciatus ]; web to level of proximal subarticular tubercle on preaxial side of IV, and just beyond proximal subarticular tubercle on postaxial side of Toe III, IV, preaxial side of V [well beyond level of proximal subarticular tubercle in P. aurifasciatus ]). Theloderma lateriticum sp. nov. further differs from P. k e m p i i in having a disc on FI (absent in P. k e m p i i), and an inner metatarsal tubercle (absent in P. k e m p i i). Theloderma lateriticum sp. nov. further differs from P. ocellatus by its brick-red iris (yellow in P. ocellatus ) and spotted lip (banded in P. ocellatus ). Theloderma lateriticum sp. nov. further differs from P. petilus with its minimal foot webbing (to discs as a fringe on every toe in P. petilus ), tubercular belly, and spinose cloacal tubercles on posterior portion of thigh (both areas smooth in P. petilus ). Theloderma lateriticum sp. nov. further differs from P. truongsonensis by its long head (HDW = HDL in P. truongsonensis ), finger subarticular tubercle formula of 1,1,2,2 (1,2,2,1 in P. truongsonensis ), Toe III being shorter than Toe V (III = V in P. truongsonensis ), and lack of tarsal fold (present in P. truongsonensis ). Theloderma lateriticum sp. nov. further differs from P. shillongensis by its long head (HDW> HDL in P. shillongensis ), pedal web (only basal web between Toes IV, and V, otherwise free in P. shillongensis ), and Toe III being shorter than Toe V (opposite condition in P. shillongensis ).

Remarks: McLeod & Ahmad (2007) noted that T. licin has the ability to change color. They further suggested that the color of a preserved specimen may be related to its color at the time of euthanasia. In our field experience, the Vietnam populations of the following species do not change color: T. asperum , T. bicolor , T. corticale , T. gordoni , T. rhododiscus , and T. stellatum .

Figures

FIGURE 2. Holotype male (AMNH 168757 / IEBR A. 0860) of Theloderma lateriticum sp. nov.

FIGURE 3. Holotype of Theloderma lateriticum (AMNH 168757 / IEBR A. 0860); (A) dorsal and (B) ventral view of body (scale = 10 mm); (C) head in lateral view (scale = 5 mm), (D) palmar view of right hand (scale = 5 mm); (E) plantar view of right foot (scale = 5 mm).