Limnonectes cintalubang, Matsui & Nishikawa & Eto, 2014

Matsui, Masafumi, Nishikawa, Kanto & Eto, Koshiro, 2014, A new burrow-utilising fanged frog from Sarawak, East Malaysia (Anura: Dicroglossidae), Raffles Bulletin of Zoology 62, pp. 679-687 : 681-684

Limnonectes cintalubang , new species

( Figs. 3–5 )

Etymology. The species name is from the Malay words “cintai”, meaning to love, and “lubang”, meaning a hole, alluding burrow-utilising habits of the new species.

Material examined. Holotype: KUHE 47859 , an adult male from Ranchan , Serian , Samarahan Division, Sarawak, East Malaysia (01°08'30"N, 110°34'57"E, 64 m asl); K. Nishikawa, 4 July 2014 . Paratypes: A total of nine specimens all from the type locality. KUHE 47824 , 47858 (two females), SRC 00088 (former KUHE 47832 ), KUHE 47815 , 47823 , 47825 , 47833 , 47834 , 47857 (seven juveniles); K. Nishikawa and K. Eto 3 and 4 July 2014 .

Diagnosis. A small species of Limnonectes (SVL 45 mm in a male and 32–43 mm in females); cephalic hump absent in mature male; pointed tusk in mature male; tympanum distinct; hindlimb relatively short, tibiotarsal articulation of adpressed limb reaching center of eye; tips of digits dilated, forming small pads; toe webs poorly developed, at least 21 / 2 phalanges free of web on fourth toe; flaps on outer edge of fifth toe and along both edges of second and third fingers not movable; dorsum relatively smooth, with only weak transverse wrinkles, without dorsolateral fold; chocolate brown dorsally without markings except for small blue spots extending to flank and limbs.

Description of holotype (measurements in mm). Snoutvent length (SVL) 45.0; habitus moderately stocky ( Figs. 3 , 4 ); head slightly enlarged, as long (HL 17.7, 39.3%SVL) as broad (HW 17.7, 39.3%SVL); cephalic hump absent; snout obtusely rounded, obtuse in profile, well-projecting beyond lower jaw; eye length (EL 6.3, 14.0%SVL) slightly shorter

than snout length (SL 6.7, 14.9%SVL); canthus rounded; lore sloping, concave; nostril dorsolateral, below canthus, slightly nearer to snout than to eye (N-EL 3.0, 6.6%SVL); internarial distance (IND 4.0, 8.9%SVL) narrower than interorbital distance (IOD 4.4, 9.8%SVL), latter wider than upper eyelid (UEW 3.3, 7.3%SVL); pineal spot absent; tympanum distinct, subcircular, length (TD 4.6,10.2%SVL) more than half eye diameter and separated from eye by two-fifths of tympanum diameter (T-EL 1.9, 4.2%SVL); vomerine teeth in oblique groups, behind line connecting rear rims of choanae, groups separated from one another and from choana by half length of one group, lower jaw with a pair of tooth like pointed projections near symphysis, about similar depth of mandible at base of projections; tongue oval, deeply notched posteriorly, without papillae; vocal sac and vocal slits absent.

Forelimb moderately thick, relatively short (FLL 27.1, 60.2%SVL); fingers slender; finger length formula: II = I <IV <III ( Fig. 3A ), first finger subequal to second; length of first, measured from distal edge of inner palmar tubercle (1FL 6.7, 14.9%SVL) slightly larger than length of eye; tips of fingers slightly swollen, forming small pads without circummarginal grooves; no webs between fingers; inner palmar tubercle moderate (IPTL 2.4, 5.3%SVL), oval, not elevated; middle palmar tubercle circular, indistinct, not contacting inner palmar tubercle; outer palmar tubercle slightly smaller than inner tubercle; proximal subarticular tubercles oval and elevated; distal subarticular tubercles low, flat and indistinct; no supernumerary metacarpal tubercles; edges of fingers with narrow ridges of skin at least distally, not freely movable.

Hindlimb thick, moderately short (HLL 65.6, 145.8%SVL) about 2.4 times length of forelimb; tibia short (TL 20.5, 45.6%SVL), heels not overlapping when limbs are held at right angles to body; tibiotarsal articulation of adpressed limb reaching to center of eye; foot (FL 20.8, 46.2%SVL) slightly longer than tibia; toe length formula I <II <V <III <IV; tips of toes swollen into distinct, small disks (disk diameter of fourth toe, 4TDW 1.0, 2.2%SVL); webbing formula: I 1 – 2 II 1 – 12 / 3 III 1 – 3 IV 3 – 1 V ( Fig. 5B ); no flap of skin along outer edge of fifth toe; subarticular tubercles oval and distinct; an elongate inner metatarsal tubercle, length (IMTL 3.4, 7.4%SVL), more than half length of first toe (1TOEL 5.6, 12.4%SVL); no outer metatarsal tubercle.

Skin very fragile in life, easily damaged when handled; dorsum relatively smooth, with faint transverse wrinkles; no warts or wrinkles on eyelid and top of snout; no transverse fold between posterior margins of eyes; moderate temporal fold from eye to above axilla; no dorsolateral ridge from posterior corner of eye to sacral region; no warts anterior to anus; side of trunk rugose, without tubercles; dorsal surface of hindlimb without warts; distal one-third of tarsus with a blunt dermal ridge extending proximally from metatarsal tubercle; throat, chest, and abdomen smooth; skin of gular region not modified; distinct brownish tinge, but without asperities, forming a nuptial pad covering medial surface of first finger from its base to level of subarticular tubercle. Color. In life, dorsum chocolate-brown without marking except for small bluish white spots scattered laterally from above tympanum to the level of sacrum ( Fig. 3 ); head with a faint orange interorbital bar posterior to eye; no dark supratympanic stripe; side of body similar to flank with light spots; upper lip without dark bars; lower lip dark brown with white spots; limbs dorsally tinged reddish brown, without dark crossbars; throat irregularly mottled with light brown ( Fig. 4B ); chest to abdomen cream without dark spots; lateral side of limbs slightly mottled with brown, especially heavily on posterior thigh, tibia, and tarsus; ventral surfaces of hand and foot light brown. In preservative, dorsal color has become darker and bluish-white spots faded to white.

Variation. Individuals of the type series are very similar to each other in coloration. However, as shown in Table 3, individual variation in body proportions is not small surely because of ontogenetic change. In adults, a single male and only two females available can not be statistically compared, but they did not overlap in many characters: the male has larger values in SVL, REL, RT-EL, RTD, RIOD, and RIPTL, and smaller values in RHL, RN-EL, RSL, RHW, RUEW, RLAL, RHLL, RTL, RFL, RIMTL, and R4 TDW than females. The point at which tibiotarsal articulation of adpressed limb reached is uniform, to center of eye, and tympanum is always distinct. In three larger paratypes, phalanges free of broad web vary from 21 / 2 to 33 / 4 on inner side, and 21 / 2 to 31 / 3 on outer side of fourth toe. Some smaller specimens have trace of dark brown bars on tibia and tarsus .

Comparisons. Limnonectes cintalubang , new species, is superficially similar to the continental L. tweediei in body size (females 32–43 mm vs. 33–41 mm in L. tweediei ), nearly smooth body lacking warts, presence of visible tympanum, and poorly developed toe webs, but is differentiated from it by lacking dorsolateral fold and yellow tinge on ventral side, and having weak transverse wrinkles on dorsum. Limnonectes rhacodus (Inger, Boeadi, & Taufik, 1996) has the back with numerous transverse wrinkles, but is much smaller (females 21–24 mm) and tympanum is partially obscured by skin (Inger et al., 1996).

The new species is easily differentiated from species of the L. kuhlii complex and L. hikidai by the presence of visible tympanum and much smoother skin. Also the new species differs from members of the L. kuhlii complex ( L. kuhlii ; L. bannaensis ; L. fujianensis Ye & Fei, 1994 ; L. isanensis McLeod, Kelly, & Barley, 2012 ; L. jarujini ; L. sisikdagu McLeod, Horner, Husted, Barley, & Iskandar, 2011 ; L. megastomias McLeod, 2008 ; L. taylori Matsui, Panha, Khonsue, & Kuraishi, 2010b , L. namiyei [ Stejneger, 1901], L. asperatus [Inger, Boeadi, & Taufik, 1996], and L. fragilis [ Liu & Hu, 1973]), by smaller body size and much less developed toe webbing (females 32–43 mm, web of fourth leaving at least 21 / 2 phalanges on each side, no movable flaps of skin on edges of fingers and toes in the new species, vs. females 40–86 mm, usually all of the toes broadly webbed to disks, and movable flaps of skin present along both edges of the second and third fingers and on outer edge of the fifth toe in the L. kuhlii complex and other related species). Small body size (females 32–43 mm in SVL), poorly developed toe webbing, and lack of movable flaps on edges of fingers and toe of the new species all apply to L. hikidai (females 34–40 mm), but they are completely different in dorsal color and skin texture as noted above.

Range. Known only from the type locality, Ranchan , Serian, Samarahan Division, state of Sarawak , East Malaysia.

flat and sparsely covered by dead leaves, but with plant roots and stones densely packing the shallow layers under the soil surface. Frogs were active after 1930 h and each always stayed near a burrow ( Fig. 6A ), into which they quickly escaped when disturbed. The burrow was up to ca. 5–10 cm in diameter ( Fig. 6B ) and had a long tunnel at the depth of 50–60 cm, and it was impossible to dig out the frog. Although only one of about 20 burrows observed had underground water, there was no pool at the immediate vicinity of the holes. The nearest water body was a stream ca. 8–12 m apart from the area.

We did not hear males calling in March, July, or December at the type locality. However, because females collected in early July possessed large ovarian eggs, the breeding season is thought to include summer seasons. The diameter of 10 eggs from a female (KUHE 47824) ranged from 1.63–1.88 (mean±1SD = 1.71±0.09) mm. Both the animal and vegetal hemispheres of eggs are creamy white in color, suggesting they are laid in shaded places.

Other species found in association with the present new species in the forest were: Leptolalax gracilis ( Günther, 1872) , Leptolalax sp. , Meristogenys jerboa ( Günther, 1872) , Nyctixalus pictus ( Peters, 1871) , and Polypedates leucomystax ( Gravenhorst, 1829) .

Natural history. The new species was found in loose slopes of secondary forests with mixed bamboo and broad-leaf trees, always on the ground. The surface of the ground is

Figures

Fig. 3. Dorsolateral view of a male holotype of Limnonectes cintalubang, new species (KUHE 47859).

Fig. 4. A, dorsal; and B, ventral views of male holotype of Limnonectes cintalubang, new species (KUHE 47859). Scale bar = 10 mm.

Fig. 5. A, ventral view of right hand; and B, foot of male holotype of Limnonectes cintalubang, new species (KUHE 47859). Scale bar = 5 mm.

Fig. 6. Habitat of Limnonectes cintalubang, new species, showing: A, a juvenile sitting near a burrow and B, the size of a burrow.