Oreolalax adelphos, Nguyen & Tapley & Kane & Tran & Cui & Rowley, 2024

Nguyen, Luan Thanh, Tapley, Benjamin, Kane, Daniel, Tran, Tuyet-Dzung Thi, Cui, Jiaxin & Rowley, Jodi J. L., 2024, A new Oreolalax (Anura: Megophryidae) from the Hoang Lien Range, northwest Vietnam, Zootaxa 5514 (6), pp. 501-524 : 509-518

Oreolalax adelphos sp. nov.

Figs. 4–7

Holotype. Adult male ( ITBCZ 3619 ; field tag LNT1144) encountered on a path through bamboo forest on Mount Po Ma Lung , Ban Lang Commune, Phong Tho District, Lai Chau Province, Vietnam (N22 37.581 E103 29.104; 2959 m elevation; Figs 2 & 3 .). Collected at 19:53 h on August 10, 2023 by Luan Thanh Nguyen, Chao Van Dat, Ly Manh Ha, and Hoang Van Hung.

Paratypes. Female ( ITBCZ 3620 ; field tag LNT1145) encountered on a path through bamboo forest on Mount Po Ma Lung , Ban Lang Commune , Phong Tho District, Lai Chau Province, Vietnam (N22 37.538 E103 29.112; 2920 m elevation) and an adult female ( ITBCZ 3621 ; field tag LNT1146) encountered on a path through bamboo forest on Mount Po Ma Lung , Phong , Ban Lang Commune , Phong Tho District, Lai Chau Province, Vietnam, (N22 37.476 E103 29.148; 2914 m elevation). Both collected at 20:30 h on August 10, 2023 by Luan Thanh Nguyen, Chao Van Dat, Ly Manh Ha, and Hoang Van Hung.

Etymology. Specific epithet ‘ adelphos ’ the masculine adjective of the transliterated Greek word meaning brother, in reference to the fact that this is the second Oreolalax species known from Vietnam and that the two species are sympatric at one site.

Suggested vernacular name. Mount Po Ma Lung toothed toad (English), Cóc răng pờ ma lung (Vietnamese).

Diagnosis. Oreolalax adelphos sp. nov. is placed in the genus Oreolalax based on its molecular phylogenetic position and the following morphological characters: prominent maxillary teeth; a rough dorsal surface with scattered large warts, covered with oval black spots; vertical pupil; and an oval tongue, notched posteriorly ( Myers & Leviton 1962; Delorme et al. 2006; Fei & Ye 2016). The new species can be diagnosed from congeneric species by the combination of the following characters: (1) SVL of adult male 38.0 mm, N= 1; adult female 46.2 mm, N= 1; (2) narrow supratympanic fold; (3) no visible tympanum; (4) head longer than wide; (5) vocal sac absent; (6) absence of subarticular tubercles on hands; (7) basal interdigital webbing on hind feet; (8) ventral surface mottled with grey and creamy white; (9) dorsal surface of head and body covered in rounded, evenly spaced and similar sized tubercles; (10) presence of dark bars on limbs; (11) greyish white and creamy white spots on the flanks, and (12) a bicoloured iris.

Description of holotype. Small sized (SVL 38.0 mm); head longer than wide, head rounded anteriorly; snout rounded in profile, protrudes slightly beyond lower jaw; loreal region concave; nares oval and positioned laterally, canthus rostralis distinct, interorbital area flat; tympanum not visible, narrow supratympanic fold extends from behind eye, terminates above axilla; ridges on head lacking; eyes large, eye diameter smaller than snout length; pupil vertical; vomerine teeth and ridges absent, maxillary teeth present; tongue free at back and posteriorly notched; vocal sac absent.

Forelimbs long and gracile; lower arm thicker than upper arm; fingers long and slender, tips of fingers rounded, finger length: II<I<IV<III, fingers lacking distinct tubercles, fringes, and interdigital webbing; inner metacarpal tubercle distinct large and rounded, palmar tubercle distinct and rounded, smaller than inner metacarpal tubercle; hind limbs, long and gracile; toes with basal interdigital webbing and narrow fringes, lacking distinct tubercles, relative toe length: I<II<V<III<IV; toe tips rounded, without discs; inner metatarsal tubercle small and rounded; outer metatarsal tubercle absent.

Dorsal surfaces of head, body and limbs densely covered with rounded, evenly spaced, and similar sized tubercles; sparse scattering of very small tubercles on upper eyelid and lateral sides of head; large tubercles on flanks, less rounded than those on dorsal surfaces; crest of supratympanic fold covered in rounded tubercles; no tubercles with black tipped asperities; throat smooth, although some small rounded tubercles clustered directly below commissure of jaw; chest, belly, and ventral surfaces of limbs smooth; chest lacking small black spines.

Colour of holotype in life: Head and dorsal surface of body greyish brown with numerous, evenly spaced brown-black spots, black spots typically covering tubercles; numerous creamy grey spots, smaller in diameter than brown-black spots but also covering tubercles; flanks greyish brown with greyish white and creamy white spots which are larger on flanks than on dorsal surface; dorsal surface of upper arms greyish brown with two brown-black bars and few creamy grey spots, lower arm greyish brown with four brown-black bars; dorsal surfaces of fingers cream with brown-black bars; dorsal surface of hind limbs dark brown, anterior surface of thigh with dark bars, posterior surface of thighs with small greyish-white spots; dorsal surface of lower leg with brown-black bars; dorsal surfaces of fingers cream with brown-black bars; throat, chest, belly mottled with grey and creamy white; iris bicolored with black reticulations, metallic silver on lower half, with a hint of copper in the upper half.

Colour of holotype in preservative: Head, dorsal surfaces of body and limbs dark brown, black; flanks with greyish white spots; dorsal surfaces of fingers grey with black bars; throat, chest, belly mottled with dark and light grey.

Variation. Ventral surface of ITBCZ 3621 is mottled with cream and grey; tibia length is greater than femur length in ITBCZ 3621 (versus femur length greater than tibia length in ITBCZ 3620 and ITBCZ 3619 ). See Table 3 for measurements of all individuals in the type series.

Sex determination and secondary sexual characters: No evidence of secondary sexual characters. Sex determined by dissection and assessment of gonads or ovaries. Large testes present in ITBCZ 3619. Small eggs present in ITBCZ 3621. No eggs observed in ITBCZ 3620.

Natural history: All individuals were associated with a high elevation bamboo forest with scattered Rhododendron ( Fig. 3A–B ). There was rain in the morning before the survey and the air temperature was 15.5 °C at the time of collection. Ambient humidity was 100%. The three individuals were encountered at night on the forest floor about 400 m away from the nearest stream. During the surveys, males were not heard calling and the females we collected were not heavily gravid. Tadpoles were not observed. A single spider was found in the digestive tract of the adult female specimen (ITBCZ 3621). Oreolalax adelphos sp. nov. is sympatric with O. sterlingae .

Distribution and conservation status: Oreolalax adelphos sp. nov. is currently known from a single location at elevations between 2914 and 2920 m, near the summit of Mount Po Ma Lung in the Hoang Lien Range ( Figs. 2 & 3 ). All individuals were collected within 100 m of the border with China. It is almost certain that the species also occurs in Jinping County, Yunnan Province, China. The species’ EOO is currently predicted to be 19.8 km 2 ( Fig. 2C ). The habitat of this species at the collection site is relatively intact. However, the forest in which this species occurs is being negatively impacted by fuelwood collection for the tourism industry. At elevations below 2300 m asl, the forest is being degraded to establish cardamom plantations. Not enough is currently known about the range of this species. If this species were to be restricted to elevations above 2500 m on Mount Po Ma Lung, and the habitat were to be increasingly degraded due to fuelwood collection this species could qualify for being assessed as Critically Endangered B1ab(iii) in accordance with the IUCN Red List of Threatened Species categories and criteria (see IUCN 2012). However, there is currently only limited data available on this species and so it likely qualifies for being assessed as Data Deficient in accordance with the IUCN Red List of Threatened Species categories and criteria (see IUCN 2012).

Comparisons: Oreolalax adelphos sp. nov. can be distinguished from all congeneric species on the basis of morphology and for species where comparable sequences exist, molecular data. The following comparisons are based on one adult male and two adult females of Oreolalax adelphos sp. nov. The SVL of the third specimen (ITBCZ 3620) is not included in the comparisons as sexual maturity of this female was not ascertained when the specimen was dissected, and it could be a subadult.

Oreolalax adelphos sp. nov. differs from O. chuanbeiensis by having a smaller adult male size, SVL 38.0 mm (versus 46.7–56.0 mm, N =13, in O. chuanbeiensis ; Hou et al. 2020), a smaller adult female size SVL 46.2 mm (versus 55.0–59.0 mm, N =3, mm in O. chuanbeiensis ; Fei & Ye 2016), interdigital toe webbing basal (versus ⅓ webbed in O. chuanbeiensis ; Fei & Ye 2016), and a mottled belly (versus immaculate in O. chuanbeiensis ).

Oreolalax adelphos sp. nov. differs from O. granulosus by having a smaller adult male size, SVL 38.0 mm (versus 48.6–61.0 mm in O. granulosus ; Fei & Ye 2016), a smaller adult female size SVL 46.2 mm (versus 47.4– 60.0 mm in O. granulosus ; Fei & Ye 2016), and a grey and creamy white mottled belly (versus yellowish white, without spots or with light grey, fine spots in O. granulosus ; Fei et al. 2012).

Species SVL adult male (mm) SVL adult female Tympanum visible? Vocal sac Interdigital toe webbing Belly pattern Skin texture on belly Tubercles on dorsum Dark bars on hindlimbs Dark triangular marking between eyes Ref Oreolalax adelphos sp. nov. 38.0 (N =1) 46.2 (N =1) No Absent Basal Mottled Smooth Rounded, evenly spaced, similar sized tubercles Present Absent This study O. chuanbeiensis 46.7–56.0 55.0–59.0 No Absent 1/3 webbed Immaculate Smooth Covered in spiny tubercles Present Absent 5, 6, (N =13) (N =3) 7 O. granulosus 48.6–61.0 47.4–60.0 No Absent 1/2 – 2/3 Immaculate Smooth Covered in small spiny Present Absent 5, 6 (N =?) (N =?) webbed or with small tubercles spots O. jingdongensis 49.3–60.3 48.7–56.5 No Absent 1/3 webbed Grey spots Smooth Covered in large tubercles with thick spines Present Present 3, 5, (N =?) (N =?) 6 O. liangbeiensis 47.5–56.3 56.0–65.7 No Absent 1/3 webbed Immaculate Smooth or Covered in large and small spiny tubercles Preset Absent 5, 6 (N =20) (N =8) granular O. lichuanensis 52.9–64.8 57.3–62.2 No Absent Basal Dark flecks Smooth Large and small spineless tubercles Not Absent 4, 6 (N =20) (N =4) reported O. longmenmontis 51.6–64.2 Not No Basal Marbled Smooth Large, scattered tubercles Present Present 7 (N =3) reported O. major 59.2–68.7 65.0–70.0 No Absent 1/3 webbed Dark spots Smooth Covered in large and small tubercles with black spines Present Absent 5, 6 (N =20) (N =2) O. multipunctatus 47.4–49.8 Not No Absent Basal With few or Not Covered in tubercles Indistinct Present 5, 6 (N =4) reported without spots reported O. nanjiangensis 52.6–60.0 53.3–58.2 No Absent Basal Immaculate Smooth Rough with small tubercles Not Absent 6, 7 (N =10) (N =8) reported O. omeimontis 49.5–58.4 51.2–56.1 No Present Basal Cloudy spots Smooth Round or small elliptic spiny tubercles Present Present 4, 5, (N =15) (N =3) 6 O. pingii 43.4–51.0 46.8–54.4 No Absent Basal Immaculate Smooth Very small tubercles Present Absent 5, 6 (N =20) (N =20) O. popei 60.0–69.0 51.7–67.0 No Absent Basal or Small spots Smooth Large tubercles Present Absent 5, 6 (N =20) (N =10) absent

(mm)

Species SVL adult male (mm) SVL adult female Tympanum visible? Vocal sac Interdigital toe webbing Belly pattern Skin texture on Tubercles on dorsum Dark bars on Dark triangular marking Ref O. puxiongensis 41.3–45.3 43.0–50.0 No Absent Absent Not clearly Granular Dense tubercles forming long spiny ridges Not Present 4, 5, (N =20) (N =10) reported reported 6 O. rhodostigmatus 57.5–73.5 62.4–70.6 Yes Absent Basal Some marbling Smooth Small spiny tubercles Not Absent 6 (N =7) (N =2) reported O. rugosus 44.3–52.6 45.0–54.0 No Absent 1/4 webbed Mottled Smooth Covered in large spiny tubercles Not Absent 3, 4, (N =10) (N =10) reported 5, 6 O. schmidti 40.0–47.0 48.0–54.0 No Absent Absent Immaculate Smooth Large and small spiney tubercles Indistinct Present 5,6 (N =30) (N =3) O. sterlingae 34.3–41.3 39.5–46.3 No Absent Basal Marbled Smooth Head and body covered in irregular shaped warts Present Absent 5, 8, (N=7) (N=11) This study O. weigoldi 58.2 (N =1) Not No Absent Not Marbling Granular Rough with spiny tubercles Present Not recorded 2, 5 reported recorded around edges O. xiangchengensis 46.7–48.7 47.3–61.4 No Absent Fully Immaculate Smooth Covered in very small spiny tubercles Absent Absent 1, 6, (N =2) (N =10) webbed This study

(mm) belly hindlimbs between eyes

Oreolalax adelphos sp. nov. differs from O. jingdongensis by having a smaller adult male size, SVL 38.0 mm (versus 49.3–60.3 mm in O. jingdongensis ; Fei & Ye 2016), a smaller adult female size SVL 46.2 mm (versus 48.7–56.5 mm in O. jingdongensis ; Fei & Ye 2016), head longer than wide (versus head wider than long in O. jingdongensis Yang & Rao 2008 ), and the absence of a dark triangular marking between the eyes (versus present in O. jingdongensis ; Nguyen et al. 2013; Fei & Ye 2016).

Oreolalax adelphos sp. nov. differs from O. liangbeiensis by having a smaller adult male size, SVL 38.0 mm (versus 47.5–56.3 mm, N =20, in O. liangbeiensis ; Fei & Ye 2016), a smaller adult female size SVL 46.2 mm (versus 56.0– 65.7 mm, N =8, in O. liangbeiensis ; Fei & Ye 2016), and basal interdigital toe webbing (versus ⅓ webbed in O. liangbeiensis ; Fei & Ye 2016), and a mottled belly (versus immaculate in O. liangbeiensis ; Fei & Ye 2016).

Oreolalax adelphos sp. nov. differs from O. lichuanensis by having a smaller adult male size, SVL 38.0 mm (versus 52.9–64.8 mm, N =20, in O. lichuanensis ; Fei & Ye 2016), a smaller adult female size SVL 46.2 mm (versus 57.3–62.2 mm, N =4, in O. lichuanensis ; Fei & Ye 2016), and head longer than wide (versus head wider than long in O. lichuanensis ; Fei et al. 2012).

Oreolalax adelphos sp. nov. differs from O. longmenmontis by having a smaller adult male size, SVL 38.0 mm (versus 51.6–64.2 mm, N =3, in O. longmenmontis ; Hou et al. 2020), interorbital region without dark triangular pattern (versus present in O. longmenmontis ; Hou et al. 2020), and dorsum covered in rounded, evenly spaced and similar sized tubercles (versus large, scattered tubercles in O. longmenmontis ; Hou et al. 2020).

Oreolalax adelphos sp. nov. differs from O. major by having a smaller adult male size, SVL 38.0 mm (versus 59.2–68.7 mm, N =20, in O. major ; Fei & Ye 2016), a smaller adult female size SVL 46.2 mm (versus 65.0–70.0 mm, N =2, in O. major ; Fei & Ye 2016), and interdigital webbing basal (versus ⅓ webbed in O. major ; Fei & Ye 2016).

Oreolalax adelphos sp. nov. differs from O. multipunctatus by having a smaller adult male size, SVL 38.0 mm (versus 47.4–49.8 mm, N =4, in O. multipunctatus ; Fei & Ye 2016), and the absence of a dark triangular marking between the eyes (versus indistinct triangular marking present in O. multipunctatus ; Fei & Ye 2016).

Oreolalax adelphos sp. nov. differs from O. nanjiangensis by having a smaller adult male size, SVL 38.0 mm (versus 52.6–60.0 mm, N =10, in O. nanjiangensis ; Fei & Ye 2016), a smaller adult female size SVL 46.2 mm (versus 53.3–58.2 mm, N =8, in O. nanjiangensis ; Fei & Ye 2016), and a mottled belly (versus immaculate in O. nanjiangensis ; Fei & Ye 2016).

Oreolalax adelphos sp. nov. differs from O. omeimontis by having a smaller adult male size, SVL 38.0 mm (versus 49.5–58.4 mm, N =15, in O. omeimontis ; Fei & Ye 2016), a smaller adult female size SVL 46.2 mm (versus 51.2–56.1 mm, N =3, in O. omeimontis ; Fei & Ye 2016), head longer than wide (versus head wider than long in O. omeimontis ; Fei et al. 2012), the absence of a vocal sac (versus presence in O. omeimontis ; Fei et al. 2012), and interorbital region without dark triangular pattern (versus present in O. omeimontis ; Nguyen et al. 2013).

Oreolalax adelphos sp. nov. differs from O. pingii by having a smaller adult male size, SVL 38.0 mm (versus 43.4–51.0 mm, N =20, in O. pingii ; Fei & Ye 2016), and a mottled belly (versus immaculate in O. pingii ; Fei & Ye 2016).

Oreolalax adelphos sp. nov. differs from O. popei by having a smaller adult male size, SVL 38.0 mm (versus 60.0–69.0 mm, N =20, in O. popei ; Fei & Ye 2016), a smaller adult female size SVL 46.2 mm (versus 51.7–67.0 mm, N =10, in O. popei ; Fei & Ye 2016), and a mottled belly (versus covered by small grey spots in O. popei Fei and Ye. 2016 ).

Oreolalax adelphos sp. nov. differs from O. puxiongensis by having a smaller adult male size, SVL 38.0 mm (versus 41.3–45.3 mm, N =20, in O. puxiongensis ; Fei & Ye 2016), dorsum covered in rounded, evenly spaced and similar sized tubercles (versus dorsum with dense tubercles forming spiny ridges in O. puxiongensis ; Fei & Ye 2016); the absence of a dark triangular marking between the eyes (versus present in O. puxiongensis, Fei & Ye 2016 ), by having smooth skin on the belly (versus granular skin on the belly in O. puxiongensis ; Nguyen et al. 2013), and head longer than wide (versus head wider than long in O. puxiongensis ; Fei et al. 2012).

Oreolalax adelphos sp. nov. differs from O. rhodostigmatus by having a smaller adult male size, SVL 38.0 mm (versus 57.5–73.5 mm, N =7, in O. rhodostigmatus ; Fei & Ye 2016), a smaller adult female size SVL 46.2 mm (versus 62.4–70.6 mm, N =2, in O. rhodostigmatus ; Fei & Ye 2016), no visible tympanum (versus distinct tympanum in O. rhodostigmatus ; Fei & Ye 2016), dorsum covered in rounded, evenly spaced and similar sized tubercles (versus dorsum fully covered in small spiny tubercles in O. rhodostigmatus ( Nguyen et al. 2013) , and greyish white and creamy white spots on the flanks (versus orange-red spots in O. rhodostigmatus ; Fei & Ye 2016).

Oreolalax adelphos sp. nov. differs from O. rugosus by having a smaller adult male size, SVL 38.0 mm (versus 44.3–52.6 mm, N =10, in O. rugosus ; Fei & Ye 2016), head longer than wide (versus head wider than long in O. rugosus Yang & Rao 2008 ), and a belly colour of mottled grey and creamy white (versus entirely beige yellow, sometimes with some grey brown mottling in O. rugosus ; Fei et al. 2012).

Oreolalax adelphos sp. nov. differs from O. schmidti by having a smaller adult female size SVL 46.2 mm (versus 48.0–54.0 mm, N =3, in O. schmidti ; Nguyen et al. 2013), the absence of a dark triangular marking between the eyes (versus present in O. schmidti ; Nguyen et al. 2013), and a mottled belly (versus immaculate in O. schmidti ; Fei & Ye 2016).

Oreolalax adelphos sp. nov. differs from O. sterlingae by having a rounded snout in dorsal and ventral view (versus almost semicircular in O. sterlingae ; material examined Fig. 7 ), supratympanic fold relatively narrow (versus thick and well developed in O. sterlingae ; Nguyen et al. 2013; material examined; Fig. 7 ), dorsal surface of head and body covered in rounded, evenly spaced and similar sized tubercles (versus head and body covered in irregular shaped warts in O. sterlingae ; Nguyen et al. 2013; Fig. 7 ), and a bicolored iris (versus uniform gold iris with black reticulations in O. sterlingae ; Nguyen et al. 2013; Tapley et al. 2020).

Oreolalax adelphos sp. nov. differs from O. weigoldi by having a smaller adult male size, SVL 38.0 mm (versus 58.2 mm, N =1, in O. weigoldi ; Ohler & Dubois 1992), a mottled belly (versus marbling around the edges in O. weigoldi ; Ohler & Dubois 1992), and by having smooth skin on the belly (versus granular skin on the belly in O. weigoldi ; Nguyen et al. 2013).

Oreolalax adelphos sp. nov. differs from O. xiangchengensis by having a smaller adult male size, SVL 38.0 mm (versus 46.7–48.7 mm, N =2, in O. xiangchengensis ; examined material; Table 5 ; Fig. 8 ), dorsum covered in rounded, evenly spaced and similar sized tubercles (versus dorsum fully covered in very small spiny tubercles in O. xiangchengensis ; examined material; Fig. 8 ), dorsal belly colour mottled with grey and creamy white (versus entirely beige yellow in O. xiangchengensis ; Fei & Huang 1983; examined material; Fig. 8 ), by having rudimentary interdigital webbing on feet (vs. fully webbed in O. xiangchengensis ; Fei & Huang 1983; examined material; Fig. 8B ), the absence of subarticular tubercles on the hands (versus presence in O. xiangchengensis ; examined material; Fig. 8B ), and the presence of dark bars on limbs (versus absent in O. xiangchengensis ; Fei & Huang 1983).

Figures

FIGURE 2. Localities where Oreolalax adelphos sp. nov., Oreolalax sterlingae and Oreolalax xiangchengensis and Oreolalax cf xiangchengensis are known to be present, confirmed with molecular data (A), Localities of Oreolalax adelphos sp. nov. and Oreolalax sterlingae in the Hoang Lien Range of Vietnam confirmed with molecular data (B), the predicted distribution of Oreolalax adelphos sp. nov. (C). Pale grey areas indicative of higher elevation, dark green indicative of lowest elevation.

FIGURE 3. Habitat Oreolalax adelphos sp. nov. (A) Microhabitat of Oreolalax adelphos sp. nov. Mount Po Ma Lung Lai Chau Province, northwest Vietnam, and (B) Macrohabitat of Oreolalax adelphos sp. nov. Mount Po Ma Lung Lai Chau Province, northwest Vietnam.

FIGURE 4. Oreolalax adelphos sp. nov. adult male holotype ITBCZ 3619 in preservative. (A) Dorsal view, (B) ventral view, (C) dorsolateral view, (D) palmar surface of left hand, and (E) plantar surface of left foot.

FIGURE 5. Oreolalax adelphos sp. nov. in situ. (A) adult male holotype ITBCZ 3619, (B) female ITBCZ 3620, and (C) adult female ITBCZ 3621.

FIGURE 6. Oreolalax adelphos sp. nov. in life under sedation. (A) dorsal view of adult male holotype ITBCZ 3619, (B) ventral view of adult male holotype ITBCZ 3619, (C) dorsal view of female paratype ITBCZ 3620, (D) ventral view of female paratype ITBCZ 3620, (E) dorsal view.

FIGURE 7. Comparison between Oreolalax sterlingae and Oreolalax adelphos sp. nov. (A) male Oreolalax sterlingae ITBCZ 3622 in life, (B) female Oreolalax adelphos sp. nov. ITBCZ 3621 in life, (C) dorsolateral view of male Oreolalax sterlingae ITBCZ 3622 in life, (D) dorsolateral view of male Oreolalax adelphos sp. nov. ITBCZ 3619, (E) oral cavity of male Oreolalax sterlingae (ITBCZ 3622) under sedation, and (F) oral cavity of female Oreolalax adelphos sp. nov. (ITBCZ 3621) under sedation.

FIGURE 8. Oreolalax xiangchengensis adult male holotype CIB 80I1286 in preservative. (A) Dorsal view, (B) ventral view, and (C) dorsolateral view.