Amolops australis, Onn & Abraham & Grismer & Grismer, 2018

Onn, Chan Kin, Abraham, Robin Kurian, Grismer, Jesse L. & Grismer, L. Lee, 2018, EleVational size Variation and two new species of torrent frogs from Peninsular Malaysia (Anura: Ranidae: Amolops Cope), Zootaxa 4434 (2), pp. 250-264 : 260-262

Amolops australis sp. nov.

Southern Torrent Frog

Fig. 8

Amolops larutensis, Ahmad, Senawi & Lim 2004 , p 26; Belabut & Hashim, 2005, p 200; Wood, Grismer, Youmans, Nasir, Ahmad & Senawi, 2008, p 118; Grismer & Pan, 2008, p. 277 (in part); Shahriza, Ibrahim, Anuar & Muin, 2012, p 558, 561.

Staurois larutensis, Belabut & Hashim, 2004 , pp. 67, 69.

Holotype. LSUHC 7665, adult female, collected on 27 August 2005 by L. Grismer, P. L. Wood, J. L. Grismer, T. M. Youmans, N. Nasir, J. Senawi, and N. Ahmad from Peta, Endau-Rompin National Park (2°26'20.09" N, 103°16'22.29"; 103 m asl).

Paratypes. LSUHC 7672–73, 7686, 8097–8101, adult males, and 7671, 7684, 7687, 8096, adult females, with the same collection data as the holotype.

Description of holotype ( Fig. 8 ). Adult female; habitus robust; head slightly wider than long; snout sharply angular, obtusely acuminate in dorsal profile, projecting significantly beyond lower jaw in lateral profile; nostrils located laterally, closer to tip of snout than to eye; canthus rostralis sharp, constricted anteriorly; lores vertical, concave; eye diameter lesser than snout length; pineal body visible, located level to the anterior margin of orbits; tympanum distinct, tympanic rim slightly elevated; vomerine teeth well developed, on two oblique, oval ridges almost contacting each other; tongue cordiform.

Forelimbs moderately robust; relative length of fingers, II<I<IV<III; fingers without webbing; tips of all fingers expanded into large discs bearing circummarginal and transverse dorsal and ventral grooves, discs of third and fourth fingers distinctly larger than discs of first and second fingers; fringe of skin along lateral edges of all fingers; subarticular tubercles slightly raised, rounded; inner metacarpal tubercle elongate, medial and outer metacarpal tubercle oval, in contact, outer slightly smaller than medial; one supernumerary tubercle posterior to proximal subarticular tubercle on second, third and fourth fingers, that on second finger barely visible.

Hind limbs robust; tips of all toes expanded into round discs bearing circummarginal and transverse dorsal and ventral grooves, width of fourth toe disc less than width of third finger disc; full web on all toes; wide, movable flap of skin on preaxial side of first toe and a narrower flap of skin on postaxial side of fifth toe from the level of the proximal subarticular tubercle to toe disc; subarticular tubercles distinct, oval; inner metatarsal tubercle very elongate, outer round, approximately one third size of inner.

Skin on dorsum and dorsal surfaces of forelimbs densely covered with mostly circular but also a few irregularly-sized, raised tubercles; tubercles on dorsolateral region slightly enlarged, elongated, ridge-like; tubercles on flanks larger than those on dorsum; tubercles almost absent on dorsal surfaces of hind limbs; supratympanic fold absent; skin on gular and chest smooth, belly slightly granular; anterior half of ventral surface of thigh smooth, posterior half granular.

Measurements of holotype (mm): SVL=46.3; HL=16.5; HW=15.8; IND=4.8; SNL=7.4; FAL=9.8; FL=25.6; TBL=26.7; Fin3DW=3.0. Additional measurements: horizontal diameter of orbit=6.4; interorbital distance=4.0; largest diameter of tympanum=2.0; distance between anterior margin of tympanum and posterior margin of orbit=1.9

Diagnosis. Amolops australis sp. nov. is placed in the genus Amolops based on its overall morphological similarity with A. gerutu sp. nov. and phylogenetic placement as its sister lineage ( Fig. 1 ). It can be distinguished from other congeners by the following combination of characters: adult females moderate in size (SVL 45.8–47.0 mm), males smaller (SVL 28.7–32.7 mm); skin on dorsum and dorsal surfaces of forelimbs densely covered with mostly circular but also a few irregularly-sized, raised tubercles; tubercles on dorsolateral region slightly enlarged, elongated, ridge-like; tubercles on flanks larger than those on dorsum; tubercles almost absent on dorsal surfaces of hind limbs; posterodorsal surface of thighs with dense, dark stippling.

Coloration in preservative. Dorsum light-gray, interspersed with irregular dark-brown spots and blotches; flanks faded white with small brown blotches; lips off-white; dorsal surface of fore and hind limbs light-gray with distinct, wide, dark-brown crossbars; dorsal surface of third and fourth fingers brown with dark-brown crossbars, second finger white, mottled with dark-brown, first finger white with minute brown speckling; posterodorsal surface of thighs with dense, dark stippling; toe webbing light-brown with fine, dense, dark-brown veins; venter orangish white; ventral surface of hands speckled with dark-brown; dark-brown stripe on outer side of forearm; gular region with irregular, dark-brown streaks; anterior half of ventral surface of thighs pale and faded-orange, posterior half dark-brown with light spots; ventral surface of feet and outer half of tarsus dark-brown; pectoral glands orangish white.

Variation. Males differ from females in being smaller; having paired vocal sacs; distinct nuptial pads on base of first finger; lacking humeral glands; and having indistinct pectoral glands.

Comparisons. Because the new species forms a clade with A. larutensis and is substantially distant from all other congeners, we restrict our comparisons to A. larutensis and the other undescribed species. Amolops australis sp. nov. differs from A. larutensis by having denser and more pronounced dorsal tubercles and posterodorsal side of thighs with dense, dark stippling as opposed to vermiculations ( Fig. 7E, G ). Males and females of A. australis sp. nov. are noticeably smaller in comparison to A. larutensis and A. gerutu sp. nov. ( Table 1; Figs. 3 , 4 ). Specifically, males of A. australis sp. nov. have smaller SVL, IND, FAL, and TBL when compared with those of A. larutensis and smaller SVL, HL, HW, IND, FAL, FL, TBL, and 3FinDW compared to A. gerutu sp. nov. ( Table 2; Fig. 3 ). For females, A. australis sp. nov. have smaller SVL, HW, and 3FinDW, but larger HL, IND, SNL, FAL, and FL when compared with A. larutensis and A. gerutu sp. nov. ( Table 3; Fig. 4 ). See the Discussion section for the use of continuous morphological characters to diagnose this species.

Distribution. Amolops australis sp. nov. is only known from the southern state of Johor where it has been confirmed to occur in Endau-Rompin National Park and Bantang River Amenity Forest. It is presumed to occur more widely in suitable habitats in the surrounding southern region of Peninsular Malaysia.

Natural history. The natural history of this species is similar to that of Amolops gerutu sp. nov. and A. larutensis . No information is available for tadpoles.

Etymology. The specific epithet is derived from the Latin word “ australis ”, meaning “southern” in English, and is applied in reference to the distribution of this species in southern Peninsular Malaysia that also represents the southern-most distributional limit of the entire genus.

Figures

FIGURE 1. Distribution of sampled populations and an ultrametric maximum-likelihood phylogeny inferred from 1,466 bp of the 16S rRNA-encoding mitochondrial gene. All major nodes were highly supported with>90% bootstrap. Populations represented by circles belong to the western clade, triangles represent populations from the eastern clade, and star denotes the type locality of Amolops larutensis at Bukit Larut, Perak. The red box indicates a contact zone between the eastern and western clades. This figure is adapted from Chan et al. (2017).

FIGURE 3. Boxplots representing the log-transformed and body-size corrected morphological characters in males. Clusters with the same letter code are not significantly different (Tukey HSD test at p<0.05). Blue=E2; purple=E1; orange=Amolops larutensis.

FIGURE 4. Boxplots representing the log-transformed and body-size adjusted morphological characters in females. Clusters with the same letter code are not significantly different (Tukey HSD test at p<0.05). Blue=E2; purple=E1; orange=Amolops larutensis.

FIGURE 7. Top row: (A) female Amolops larutensis from Fraser’s Hill, Pahang; (B) female A. gerutu from Chemerong, Pahang; Middle row: (C) male A. larutensis from Fraser’s Hill; (D) male A. gerutu from Sekayu, Terengganu; Bottom row: (E) color-pattern comparisons of the posterodorsal portion of the thigh that diffentiates A. larutensis from (F) A. gerutu and (G) A. australis.

FIGURE 8. Holotype (LSUHC 7665) of Amolops australis from Endau-Rompin (Peta), Pahang.