Occidozyga berbeza, Matsui & Nishikawa & Eto & Hamidy & Hossman & Fukuyama, 2021

Matsui, Masafumi, Nishikawa, Kanto, Eto, Koshiro, Hamidy, Amir, Hossman, Yazid & Fukuyama, Ibuki, 2021, A new Occidozyga from Sarawak, Malaysian Borneo (Anura: Dicroglossidae), Zootaxa 4926 (4), pp. 535-546 : 539-544

Occidozyga berbeza sp. nov.

( Figs. 4 , 5 , 6 )

Limnonectes rhacodus (part): Pui et al. 2013, p. 1588; Das et al. 2015, p. 7.

Occidozyga baluensis (part): Wahab et al. 2014, p. 12.

Holotype. SRC 00022 (former KUHE 53037 ), an adult female from Gunung (= Mt.) Serapi , Kubah National Park , Matang , Kuching District, Sarawak, East Malaysia (01°36’25”N, 110°11’27”E, 282 m asl), collected on 14 August 2009 by M. Matsui.

Paratypes. A total of seven specimens (four females and three males) all from the type locality. KUHE 17220 : 12 August 1993 ; KUHE 17327 , 17328 , 17332 : 18 August 1993, collected by M. Matsui. SRC 00383, 00384 (former KUHE 57072 , 57073 ) , SRC 00906: 18 August 2016, collected by K. Nishikawa, and K. Eto.

Referred specimens. A total of three specimens (all males) from Ranchan , Serian , Samarahan Division, Sarawak, East Malaysia (01°08’30”N, 110°34’57”E, 64 m asl), KUHE 47827 , 47828 : 3 July 2014 ; KUHE 47856 : 4 July 2014, collected by M. Matsui and K. Eto.

Etymology. The specific epithet berbeza is a Malay word denoting “contrasting,” alluding to the contrasting orange and dark brown dorsal color of the new species.

Diagnosis. A small-sized (SVL 16–18 mm in adult males and 18–19 mm in adult females) stocky species ( Fig. 4 ) of the genus Occidozyga ; mandible with a single median cusp; retracted tongue rounded posteriorly; tympanum hidden or only anterior rim visible; no dorsolateral fold; limbs short, heavy; tibiotarsal articulation of adpressed limb reaching, at most, posterior border of eye; tips of fingers rounded, lacking disks; no vomerine teeth; nostrils dorsal; tips of toes with disks, only first and second toes webbed to disks; males with a nuptial pad, and internal subgular vocal sac.

Description of holotype (measurements in mm). Snout-vent length (SVL) 18.2; body stocky ( Fig. 5 ); head truncate, longer (7.3, 40.1 % of SVL) than wide (7.0, 38.5 % SVL); snout tip rounded in dorsal and lateral outline, scarcely projecting beyond lower jaw; canthus broadly rounded; lores vertical, slightly concave; nostril raised and oriented dorsally on canthus, slightly nearer to anterior margin of upper eyelid (1.0, 5.5 % SVL) than to tip of snout (1.2, 6.6 % SVL); internarial distance (1.6, 8.7 % SVL) longer than distance from nostril to eye; eye moderate, length (2.7, 15.1 % SVL) nearly three times eye-nostril distance, larger than snout length (2.2, 12.1 % SVL); interorbital surface flat, much narrower (1.1, 5.9 % SVL), than width of upper eyelid (1.8, 9.6 % SVL) and internarial distance; tympanum hidden and only anterior rim visible; vomerine teeth absent; tongue narrow, rear margin entire, without papilla.

Forelimb (8.7, 46.0 % SVL) short, heavy ( Figs. 4 , 5 ); fingers moderate, unwebbed, with weak fringes of skin along inner and outer sides ( Fig. 6A ); relative length of fingers: II<I<IV<III, first, second, and fourth fingers subequal; finger tips rounded without disks; two small palmar tubercles on metacarpal region; subarticular tubercles prominent, oval.

Hindlimb short (27.4, 150.5 % SVL), heavy, slightly more than three times length of forelimb; tibia (8.9, 48.7 % SVL) slightly longer than foot (8.4, 46.0 % SVL); heels not touching when limbs held at right angles to body; tibiotarsal articulation of adpressed limb reaching just to posterior corner of eye; toe tips with pear-shaped disks, that of second toe wider, and fifth toe narrower than other disks; relative length of toes: I<V<II<III<IV, third toe longer than fifth; web margins smooth, not crenulate, formula I 1–1 II 1–1 III 1– 21 / 2 IV 3– 11 / 2 V ( Fig. 6B ); subarticular tubercles prominent, oval; inner metatarsal tubercle compressed (1.0, 5.5 % SVL), about half length of first toe (2.1, 11.5 % SVL); outer metatarsal tubercle absent.

Dorsal skin with transverse wrinkles; eyelid with small tubercles; dermal fold present, running in straight line from eye to insertion of arm; dorsolateral fold absent; sides scattered with small, low glands; throat and chest smooth; abdomen smooth throughout; dermal fringe present along inner side of first toe and outer side of fifth toe and metatarsal segment of foot; tarsal ridge present.

Color. In life, dorsal head and body orange-brown; dorsal stripe broad, dark-brown, running from tip of snout posteriorly, and diverging at sacrum, continuing across the groin to femur and tibia; area anterior to skin fold between eye and arm insertion with whitish-yellow markings; interorbital bar dark brown, united to dorsal stripe; ventral body surfaces cream, with large scattered dark gray spots on throat and posterior thigh; digits dark brown ventrally, web transparent; dorsal surfaces of lower arm and tarsal segment of limb barred dark-brown; rear of thigh without marking. In preservative, color has generally faded but pattern has not obviously changed.

Variation. Males have relatively wider heads (38.7–41.4 % of SVL) than females (35.7–38.7 % SVL) and smaller inner metatarsal tubercles (males: 4.6–5.4 % SVL; females: 5.5–5.9 % SVL; Table 3). One male ( SRC 00906) has a small vocal sac opening very close to jaw at left corner of mouth; the nuptial pad covers the medial surface of the first finger from its base to the last phalanx. In all three males and one female, the tibiotarsal articulation of the adpressed limb reaches the posterior corner of eye, and in the remaining three females, this articulation does not reach the posterior corner of the eye, as it does in the holotype. Outer metatarsal tubercles are usually absent (only one individual ( SRC 00906) had a minute tubercle (0.9 mm) on the plantar surface of its right foot). One female ( KUHE 57073 ) had a thin, light vertebral line in its dark dorsal band, and the wide dark brown middorsal band is interrupted by a narrow transverse band of orange brown ground color just behind eyes.

Comparisons. Data for congeneric species were obtained from the collection of KUHE, MZB, and SRC, and those shown in Inger (1954, 1966), Taylor (1922, 1962), Iskandar (1998), Iskandar et al. (2011) and Matsui (1979). Data for Limnonectes rhacodus are from the type series in MZB (Amph 2991–2994).

The new species, Occidozyga berbeza has a mandibular symphysis with a single median cusp, which differs from Limnonectes rhacodus , a species that has mandibular symphysis with a medial cusp and two lateral odontoid processes ( Fig. 2C, D ).

Among members of Occidozyga , O. berbeza sp. nov. most resembles O. diminutiva (Taylor) from the Philippines in many morphological characteristics, such as its fourth toe with one or two terminal phalanges free of web, only the toes have terminal disks, and its fingers lack enlarged disks. However, the new species differs from O. diminutiva in having male and female SVL less than 20 mm, by possession of dorsally oriented nostrils, an unnotched tongue, no dorsolateral skin fold, and skin of back with numerous transverse wrinkles (vs. female SVL 26 mm, nostrils lateral, tongue slightly notched, a thin dorsolateral skin fold from eye halfway to groin, and skin of back smooth or faintly shagreened in O. diminutiva ).

Occidozyga berbeza sp. nov. differs from O. baluensis from Borneo by a SVL less than 20 mm, its whitish abdomen, and the lack of an outer metatarsal tubercle and dorsolateral skin fold (vs. SVL 16–26 mm in males and 33–34 mm in females, abdomen spotted black and brown, usually with outer metatarsal tubercle and dorsolateral skin fold).

Occidozyga berbeza sp. nov. differs from O. celebensis Smith from Sulawesi, Indonesia by having toes with terminal disks (vs. toes at most with conical tips).

The new species differs from O. floresiana Mertens from Flores, Indonesia, by having fingers with blunt tips (vs. fingers with terminal disks in O. floresiana ).

Occidozyga berbeza sp. nov. differs from O. laevis from the Philippines in having SVL less than 20 mm and longer toes, which are not webbed to disks (vs. male SVL of 22–40 mm and female SVL of 27–62 mm, and fourth toe broadly webbed to disk).

Occidozyga berbeza sp. nov. differs from O. lima from India, Bangladesh, Myanmar, Thailand, and Laos, China, Vietnam, Malaysia, and Java and Bali, by having a SVL less than 20 mm, transversely wrinkled dorsal skin, toe tips with disks, and no marking on rear of thigh or chin stripes (vs. female SVL 26–32 mm and male SVL 22–26 mm, dorsum strongly tuberculate, toe tips pointed, bold black horizontal stripe on rear of thighs, and strongly patterned venter with pair of dark chin stripes).

Occidozyga berbeza sp. nov. having male SVL of 16–18 mm is similar to O. magnapustulosa (Taylor & Elbel) from Thailand with male SVL of 16–21 mm, but differs from it by fingers not webbed, toe tips with disks, fourth toe not webbed to disk, a transversely wrinkled dorsum, and chin and throat whitish and spotted with black (vs. remnant of webs between two inner fingers, toe tips blunt, lacking disks, web extending to toe tips, without deep incision, dorsum covered with craterlike warts, some of which have white tips, and throat of males heavily pigmented in O. magnapustulosa ).

Occidozyga berbeza sp. nov. differs from O. martensii from Thailand, China, Vietnam, Laos, Myanmar, and Malaysia by having a SVL less than 20 mm, a transversely wrinkled dorsum, and a whitish chin and throat spotted with black (vs. female SVL of 26–28 mm and adult male SVL of 19–24 mm, lightly rugose dorsum, and chin and throat dark in males, or dusky to immaculate in females).

Occidozyga berbeza sp. nov. differs from O. semipalmata Smith from Sulawesi, Indonesia by having blunt finger tips (vs. fingers with flattened terminal disks, slightly wider than the diameter of penultimate phalange).

Occidozyga berbeza sp. nov. differs from O. sumatrana from Peninsular Thailand and Malaysia, Sumatra, Bali, and Java by having a SVL less than 20 mm, fourth toe not webbed to disk, a transversely wrinkled dorsum, light brown dorsum with a broad black band (vs. female SVL of 35–48 mm and male SVL of 20–31 mm, hind feet fully webbed, and dorsum grey-brown or olive-brown, usually mottled dark brown).

The new species differs from O. tompotika Iskandar, Arifin & Rachmanasah from Sulawesi, Indonesia in having blunt finger tips not wider than phalange diameter (vs. disks of fingers much larger than phalange diameter).

Range. Southwestern Sarawak, Malaysian Borneo. Kuching Division: Kuching, Matang. Gunung Penrissen, Padawan ( Pui et al. 2013, reported as Limnonectes rhacodus ); Samarahan Division: Serian.

Natural History. The holotype and some paratypes were obtained on the damp forest floor near a pond and a stream at low elevation. Other paratypes were near shallow pools and jumped into there when disturbed. Other species found in this locality were: Ansonia leptopus (Günther) , Ingerophrynus divergens (Peters) , Leptolalax gracilis (Günther) , Limnonectes conspicillatus (Günther) , L. hikidai Matsui & Nishikawa , L. palavanensis (Boulenger) , Kalophrynus heterochirus Boulenger , Microhyla borneensis Parker , M. malang Matsui , Pulchrana picturata (Boulenger) , Kurixalus chaseni (Smith) , and Nyctixalus pictus (Peters) . No calls or amplectant pairs were observed during fieldwork conducted in early June and mid-August. Females collected in mid-August appeared to have completed laying eggs, and one female (KUHE 17220) had a few, dark brown ova in the ovaries. Oviposition site(s) and larvae are presently unknown.

Figures

FIGURE 2. Dorsal view of body (A, B) and frontal view of mandible (C, D) of Limnonectes rhacodus (holotype, MZB Amph 2991: A, C) and Occidozyga sp. from Matang (KUHE 53037: B, D), showing dorsum similarly with transverse wrinkles (A, B) and different mandible shape (with a median and two lateral cusps in C and with a single median cusp in D). Not to scale.

FIGURE 4. Dorsolateral view of female holotype of Occidozyga berbeza sp. nov. (SRC 00022 (former KUHE 53037)).

FIGURE 5. Dorsal (A) and ventral (B) views of female holotype of Occidozyga berbeza sp. nov. (SRC 00022 (former KUHE 53037)). Scale bar = 5 mm.

FIGURE 6. Ventral view of hand (A) and foot (B) of female holotype of Occidozyga berbeza sp. nov. (SRC 00022 (former KUHE 53037)). Scale bar = 5 mm.