Megophrys acehensis, Munir & Nishikawa & Hamidy & Smith, 2021

Munir, Misbahul, Nishikawa, Kanto, Hamidy, Amir & Smith, Eric N., 2021, Two new species of Megophrys Kuhl and Van Hasselt (Amphibia: Megophryidae) from Sumatra, Indonesia, Zootaxa 5057 (4), pp. 503-529 : 514-520

Megophrys acehensis sp. nov.

( Figs. 4 A−D, 5A−E)

Holotype MZB. Amph 26098 (field number ENS 18664; GenBank accession no. MT 710708 ; Figs. 4 A−B, 5A−E; Megophrys sp. north in Fig. 1 and Table 1 ), adult male collected at 2330 h on 5 August 2015 from Aceh Province, Aceh Tengah Regency, Linge District , Kute Robel (4.506444 °N, 96.860750 °E, 1638 m a.s.l), by Elijah Wostl , Ilham Fonna , and Muhammad Iksan ( Fig. 6 ).

Paratype UTA A–66178 (field number ENS 21030; GenBank accession no. MT 710709 ; Fig. 4C–D ), a sub adult male collected on at 1856 h on 1 June 2016 from Aceh Province, Pidie Regency, Geumpang District, UPT V Geumpang (4.854540 °N, 96.216540 °E, 1086 m a.s.l) by Michael B. Harvey and Eric N. Smith ( Fig. 6 ) .

Etymology. The specific name acehensis is derived from the province of Aceh in northern Sumatra and the Latin suffix– ensis meaning from that place.

Suggested English common name. Aceh Horned Frog

Suggested Indonesian name. Katak–tanduk Aceh

Diagnosis. The new species was assigned to the genus Megophrys based on the combination of the following morphological characters, as defined by Kuhl and van Hasselt (1822) and Delorme et al. (2006): (1) pointed snout profile, bearing a pointed projection, protruding laterally beyond the lower jaw; (2) broad and flattened eyelid with palpebral projection; (3) possession of a broad and depressed head; (4) conical spine at the corner of mouth; (5) vertical pupil; (6) presence of maxillary and vomerine teeth. Megophrys acehensis sp. nov. can be diagnosed from its geographically relevant congeners in the Sunda Shelf and the Philippines by the following combination of characters: medium body size, stocky (SVLh 38.1 mm in adult male); snout pointed with a short, acute rostral appendage (RSAL 1.3% in adult male); relatively short triangular palpebral projection with acute tip (EHL 25.1% UEWh in adult male); head length relatively short (RHLh 37.2% in adult male); head wider than its long (HW 113.6% HLh in adult male); tympanum distinct, about one-third of eye diameter (TDH 35.6% ED in adult male), nearly rounded (TDH 85.9 % TDV in adult male); vomerine teeth present; a pair of dorsolateral folds, extending from shoulder, above axilla to groin; dorsal and lateral skin tuberculate, shagreened on the throat to belly; short lower arm (RLAL 45.8% in adult male); foot nearly as long as thigh (FL 96.6% TL in adult male); tibiotarsal articulation reaching posterior of eye; toe webbing absent.

Description of holotype (measurements in mm). Adult male, medium body size (SVLh 38.1, SVL 37.4) and habitus stocky; head depressed and broad, wider (HW 16.4, 42.9% SVLh) than long (HL 13.3, 34.9% SVLh); snout short (SL 4.2, 11.1% SVLh), pointed at tip with acute short rostral appendage (SAL 0.7, 1.8% SVLh), laterally protruding and projecting beyond lower jaw; nostril positioned laterally, near to snout than to eye; eye positioned laterally, large, nearly three times of tympanum horizontal diameter (ED 5.5, 280.5% TDH), eye diameter slightly wider (ED 5.5, 14.4% SVLh) than snout–horn length (SLh 5.4, 14.2% SVLh), about two and three-quarter times of nostril–eye length (ED 275% NEL), pupil vertical elliptical; canthus rostralis with sharp, angular ridge, lore sloping and concave; internarial distance (IND 4.0, 10.4% SVLh) about two-thirds of interorbital distance (IND 68.4% IOD); palpebral projection length about one-quarter of total upper eyelid width (EHL 1.2, 25.1% UEWh), tip acute, surface smooth and scattered with small and low tubercles; tympanum distinct, smooth, oval, slightly rounded (TDV 2.3, 6.0% SVLh; TDH 2.0, 5.1% SVLh; TDH 85.9% TDV); angular supratympanic fold, distinct, widened anteriorly, narrowed posteriorly, extending from behind eye, curving down around upper border of tympanum and ending above axilla; white conical tubercles behind the supratympanic fold and anterior to axilla; spinous gland on corner of mouth on jaw angle; single row of maxillary teeth present; vomerine teeth in two widely separated groups, at level posterior borders of choana; tongue lanceolate, notched posteriorly, without papillae; median subgular vocal sac present, having slit–like opening on each side of jaw commissures.

* Fold forming Y, X or H on the parietoscapular region to the level of axilla; ** Dorsolateral fold shape: dorsolateral folds are elongated and extend from the parietoscapular region to the groin (Type I); dorsolateral folds extend from the central of parietoscapular region to mid-body (Type II); multiple dorsolateral folds - at least three or four - and they are discontinuous, formed by a series of elongated tubercles (Type III); dorsolateral folds are elongated and curve from the axillary region towards (and reaching) the posterior dorsal margin of tympanum (Type IV).

Forelimb slender and short, hand length about half of arm length (HAL 9.5, 54.3% LAL), lower arm proximally enlarged, wider than upper arm; fingers moderately slender, with rounded and swollen tips, unwebbed and lacking of lateral fringes; finger length formula I<II<IV<III (fin1L 2.6, 6.9% SVLh; fin2L 3.2, 8.4% SVLh; fin4L 3.5, 9.2% SVLh; and fin3L 4.9, 12.8% SVLh); subarticular tubercles absent; outer palmar tubercle smaller than inner (OPTL 1.9, 5.0% SVLh; IPTL 2.5, 6.6% SVLh).

Hindlimb slender, moderately long (HLL 52.0, 136.5% SVLh), thigh (FML 17.1, 44.8% SVLh) slightly longer than tibia (TL 15.4, 40.4% SVLh), about twice of tarsus length (TSL 8.5, 22.3% SVLh), and nearly as long as foot (FL 14.9, 39.1% SVLh); toe length formula I<II<V<III<IV (Toe1L 2.1, 5.4% SVLh; Toe2L 3.3, 8.6% SVLh; Toe5L 4.5, 11.8% SVLh; Toe3L 4.6, 12.0% SVLh; and Toe4L 7.8, 20.6% SVLh); tibiotarsal articulation reaching to posterior corner of eye; inner metatarsal tubercle moderately large (IMTL 2.0, 5.1% SVLh), outer absent; subarticular tubercles absent, toes with rounded and swollen tips, toes web absent.

Dorsal skin surface tuberculate, low dense tubercles in entire dorsal and larger-sized tubercles mostly on forelimb, hindlimb, flanks and groin, shagreened in preservative; a pair of dorsolateral folds present, one on each side, extending from shoulder above the axilla to groin; vent with dorsal dermal accessory extension; transverse folds on limbs present, three on lower arm, three on thigh and three on tibia; limbs skin laterally tuberculate, larger size of tubercles than on dorsal side; ventral skin smooth shagreened on throat to chest, but smooth on belly and limbs, wrinkled in preservative; a pair of white conical pectoral glands, at base of axilla; white conical femoral glands, at the mid flanks of the posterior thigh; dark brown microspinules nuptial pads covering dorsal and median surfaces of the distal half of metacarpal and proximal half of basal phalanx of first and second fingers.

Coloration. In life ( Fig. 4A–B , 5A–B ), pupil dark, iris golden–brown, base of dorsum immaculate dark brown with indistinct dark brown inverted triangle pattern on parieto-orbital to scapular region and inverted “V” like pattern on back, positioned closer to vent than to parietal region; dorsal surface of head, forelimb and hindlimb darker than lateral body; dark brown transverse folds present on dorsal surface of forearm, thigh and tibia, two on the forearm, three on thigh and three on tibia, fingers with dark brown crossbars, one on first and second fingers, two on third and fourth fingers; dorsomedial surfaces of first and second fingers with dark brown microspinular nuptial pads; knee with irregular dark brown spots; dorsal surface and lateral sides of head dark brown, irregular lighter brown pattern below canthus rostralis, light brown on underside of eyelids; body flanks dark brown and unmarked, lighter than dorsum; forelimb flanks dark brown, as dorsum; hindlimb flanks cream with dark brown blotches; ventral surface from throat to chest dark brown with heavy dark longitudinal marking; belly and underside of fore- and hindlimbs light cream with dark brown blotches; in preservative, pattern remains, but dorsal, lateral, and ventral surfaces are darker ( Fig. 5C ).

Variation. The two type specimens are morphometrically similar. The holotype has slightly longer rostral appendage, head, and snout-nostril and snout lengths, but a slightly shorter palpebral projection, and a thicker and narrower head. Morphometric variation is shown in Table 2 . The transverse fold in the occipital region varies in degree of development, being distinct on the holotype but indistinct on the paratype. The dorsal coloration in life is dark brown on the holotype and orange-brown on the paratype. The ventral color of the two specimens is marbled with brown in both specimens but, the background color of the holotype is cream anteriorly and light grey posteriorly while that of the paratype is dark orange anteriorly and whitish posteriorly ( Fig. 4 A−D).

Comparisons. Megophrys acehensis sp. nov. differs from its most similar congener, M. parallela by having dorsolateral folds extending to the groin (vs. maximum of two-thirds length of trunk: Inger and Iskandar, 2005; Munir et al., 2018), a rostral appendage present (vs. absent: Inger and Iskandar, 2005; Munir et al., 2018), shagreened ventral surface from throat to belly (vs. smooth: Inger and Iskandar, 2005; Munir et al., 2018), and a relatively shorter foot to thigh ratio—FL 92.1−96.6% TL (vs. 105.4−112.5% TL: Munir et al., 2018). From M. montana , the new species differs by having tuberculate dorsal skin surface (vs. smooth: Munir et al., 2018), shagreened skin on throat (vs. smooth: Munir et al., 2018), a relatively short foot to thigh ratio—FL 92.1−96.6% TL (vs. FL 106.2−115.6% TL: Munir et al., 2018), and absent toe webbing (vs. rather developed webbing from second to fifth toes: Munir et al., 2018). From Megophrys selatanensis sp. nov., Megophrys acehensis sp. nov. differs by having a longer rostral appendage—SAL 1.3–1.8% SVLh (vs. SAL 0.3−0.6% SVLh), a slightly longer palpebral projection —EHL 25.1–28.4% UEWh (vs. EHL 21.3–24.3% UEWh), slightly narrower ratio of head width to its length—HW 114.1−115.3% HLh (vs. HW 119.3−126.4% HLh), wider ratio of tympanum to eye diameter—TDH 35.6−37.5% ED (vs. TDH 27.3−28.5% ED), tympanum nearly rounded—TDH 85.9–93.8 TDV (vs. vertically elongated, TDH 46.5−61.9% TDV), slightly shorter lower arms—LAL 44.8–45.8% SVLh (vs. LAL 48.0–49.2% SVLh), tuberculate dorsal skin surface (vs. smooth), shagreened skin on throat (vs. smooth), and absent toe webbing (vs. toes webbed at base). Megophrys acehensis sp. nov. differs from M. lancip by males having a shorter rostral appendage—SAL 1.3−1.8% SVLh (vs. SAL 2.9−3.1% SVLh in males, but overlapped with females SAL 1.4−4.1% SVLh: Munir et al., 2018), shorter head length—HLh 37.2–37.8% SVLh (vs. HLh 42.1–44.6% SVLh; Munir et al., 2018), wider head in males—HW 114.1–115.3% HLh (vs. HW 103.2–105.8% HLh in males, but overlapped with females HW 110.6–116.0% HLh: Munir et al., 2018), wider tympanum relative to eye diameter—TDH 35.6−37.5% ED (vs. TDH 25.7−28.0 ED: Munir et al., 2018), tympanum nearly rounded—TDH 85.9–93.8 TDV (vs. vertically elongated, TDH 61.1−69.1% TDV), relatively short foot to thigh ratio—FL 92.1−96.6% TL (vs. FL 102.5−109.8% TL; Munir et al., 2018), and toe webbing absent (vs. rather developed on first to fifth toes, see Figs. 4D, I , 5B in Munir et al., 2018).

Megophrys acehensis sp. nov. differs from M. nasuta by the absence of additional lateral flank folds (vs. presence: Munir et al., 2018, 2019), males being smaller—known adult male 37.4 mm SVL (vs. SVL 66.0– 93.4 mm: Munir et al., 2019), shorter acute rostral appendage—SAL 1.3−1.8% SVLh (vs. acuminate rostral appendage, SAL 1.8−9.2% SVLh: Munir et al., 2019), and shorter acute palpebral projection—EHL 25.1−28.4% UEWh (vs. acuminate palpebral projection, EHL 32.7−61.4% UEWh: Munir et al., 2019). From M. kalimantanensis , the new species differs by the absence of additional flank folds (vs. present: Munir et al., 2019), smaller body size in males—known adult male 37.4 mm SVL (vs. SVL 64.3–100.6 mm: Munir et al., 2019), slightly longer rostral appendage—SAL 1.3−1.8% SVLh (vs. SAL 0.1−0.8% SVLh: Munir et al., 2019), and shorter palpebral projection—EHL 25.1−28.4% UEWh (vs. 30.9−53.2% UEWh: Munir et al., 2019). From M. stejnegeri , the new species differs by having dorsolateral folds extending to the groin (vs. maximum of two-thirds the length of the trunk: Inger 1954), males being smaller—known adult male 37.4 mm SVL (vs. adult male 40.6−60.0 mm: Taylor, 1920; Inger, 1954), vomerine teeth present (vs. absent: Taylor, 1920; Inger et al., 1954), and smooth skin on the posterior of tympanum (vs. tuberculate, see figure 37 by Diesmos et al., 2015 and figure 18 by Sanguila et al., 2016).

Megophrys acehensis sp. nov. can be distinguished from M. kobayashii by having type I dorsolateral folds (vs. type II, see Table 3 ), absent additional lateral flank folds (vs. present: Malkmus and Matsui, 1997; Munir et al., 2018), males being smaller—known adult male 37.4 mm SVL (vs. 93.0−101.0 mm: Inger and Stuebing, 2005), rostral appendage present (vs. absent: Malkmus and Matsui, 1997), and smaller and fewer tubercles on flanks (vs. larger and numerous: Malkmus and Matsui, 1997). From M. ligayae , the new species differs by having type I dorsolateral folds, extended to the groin (vs. type II, reaching a maximum of two-thirds of trunk: Taylor, 1920; Inger, 1954; Munir et al., 2018), absent additional lateral folds (vs. present: Taylor, 1920; Inger, 1954; Munir et al., 2018), males being smaller—known adult male 37.4 mm SVL (vs. SVL 60.4−69.0 mm: Taylor, 1920; Inger, 1954), and toe webbing absent (vs. rather developed web on third, fourth, and fifth toes: Diesmos et al., 2015). Megophrys acehensis sp. nov. differs from M. edwardinae by having type I dorsolateral folds (vs. absent: Inger 1989), a rostral appendage present (vs. absent: Inger 1989), vomerine teeth present (vs. absent: Inger 1989), and slightly shorter thighs—TL 40.4−41.8% SVLh (vs. TL 45.0−50.0% SVL: Inger 1989). Megophrys acehensis sp. nov. can be distinguished from M. baluensis by having type I dorsolateral folds (vs. type III: Munir et al., 2018), males being slightly smaller—known adult male 37.4 mm SVL (vs. SVL 41.0−45.0 mm: Inger et al., 1995), a rostral appendage present (vs. absent: Boulenger, 1899; Inger, 1966; Inger et al., 1995), having a triangular palpebral projection (vs. small like tubercle: Inger, 1989; Inger et al., 1995), having smaller and fewer tubercles on body flanks (vs. larger and numerous: Inger et al., 2017), and adpressed tibiotarsal articulation reaching posterior of eye (vs. shoulder: Boulenger, 1899).

Megophrys acehensis sp. nov. can be distinguished from M. dringi , M. aceras and M. longipes by the absence of Y, X,>–<or H shaped folds on dorsal (vs. presence: Boulenger, 1885, 1903; Inger et al., 1995, see Table 3 ). Furthermore, from M. dringi , the new species being smaller in male—known adult male 37.4 mm SVL (vs. SVL 43.0−47.0 mm: Inger et al., 1995), having a stocky body (vs. slender: Inger et al., 1995), a rostral appendage present (vs. absent: Inger et al., 1995), having a triangular palpebral projection (vs. small like tubercle: Inger et al., 1995), vomerine teeth present (vs. absent: Inger et al., 1995), distinct tympanum (vs. partially obscured: Inger et al., 1995). From M. aceras , the new species differs by having smaller body size in male—known adult male 37.4 mm SVL (vs. SVL 48.0− 62.4 mm: Inger and Iskandar, 2005), a stocky body (vs. slender: Boulenger, 1903), rostral appendage present (vs. absent: Boulenger, 1903), tibiotarsal articulation reaching to posterior corner of eye (vs. shoulder, angle of jaws or temporal area: Taylor, 1962), toes web absent (vs. rather developed web on third, fourth, and fifth toes: Taylor, 1962, see figure 5 in Munir et al., 2018). From M. longipes , the new species differs by having a smaller body size in male—known adult male 37.4 mm SVL (vs. SVL 38.9−45.2 mm: Inger and Iskandar, 2005), having a stocky body (vs. slender: Boulenger, 1885), a rostral appendage present (vs. absent: Boulenger, 1885), having a triangular palpebral projection (vs. small like tubercle: Boulenger, 1885; Taylor, 1962), shorter thigh—TL 0.41−0.42 SVL (vs. TL 0.55−0.60 SVL: Inger and Iskandar, 2005) and tibiotarsal articulation reaching posterior corner of eye (vs. far beyond tip of snout; Boulenger 1885).

Distribution and Natural History. The holotype of Megophrys acehensis sp. nov. was collected on leaf litter in a sloping area at the edge of a primary forest near a stream, while the paratype was collected from leaf litter in a palm oil plantation near the edge of an old secondary forest. Landslides, new road development, and monoculture forests have become major threats at the holotype locality, while the threats at the paratype locality were the land use changes and water pollution from palm oil fields. The precise distribution, population, habitat requirements, breeding behavior, call and tadpole information are unknown. The following anuran species have been found sympatrically with the new species, at holotype locality: Limnonectes sp ; Philautus larutensis ; Sumaterana dabulescens Arifin, Smart, Hertwig, Smith, Iskandar, and Hass ; at the paratype locality: Chalcorana chalconota ; Leptophryne borbonica ; Limnonectes kuhlii ; L. macrodon ; Limnonectes sp. ; Rhacophorus catamitus ; Philautus sp. and Pulchrana fantastica Arifin, Cahyadi, Smart, Jankowski, and Haas.

Figures

FIGURE 1. Phylogenetic tree based on Maximum Likelihood tree from 471 bp of 16S rRNA gene, values above or below branches represent bootstrap support for Ultrafast Bootstrap Probability, Bayesian Inference posterior probability (UFB/ BPP). The number at the tip of branches corresponds to sample numbers in Appendix 1.

FIGURE 4. Megophrys acehensis sp. nov. in life, adult male holotype MZB.Amph 26098 (A−B), subadult male paratype UTA A-66178 (C−D).

FIGURE 5. Megophrys acehensis sp. nov., adult male holotype (MZB. Amph 26098; SVL 37.4 mm): dorsal (A), ventral (B), lateral head (C), ventral right hand (D), and ventral right foot (E) views, scale = 5 mm.

FIGURE 6. Map of Sumatra showing the known distribution of Sumatran Megophrys. Numbers on map correspond to sample identifiers with molecular data (see Appendix 1), filled markers showed the holotype locality, and markers without numbers are based on the referred specimens or references (see Munir et al., 2018). Black dashed lines indicate major biogeographic breaks within Sumatran Megophrys, modified from (O’Connell et al., 2018a; Shaney et al., 2020). The biogeographic boundary between central and northern Sumatra in this study is different from the one proposed by O’Connell et al. (2018a) and Shaney et al. (2020) because there is still uncertainty as to where that exact boundary occurs.