Bronchocela hayeki ( Müller, 1928 )

Amarasinghe, A. A. Thasun, Kamsi, Mistar, Riyanto, Awal, Putra, Chairunas A., Hallermann, Jakob, Andayani, Noviar, Abinawanto, A. & Supriatna, Jatna, 2022, Taxonomy, distribution, and conservation status of a rare arboreal lizard Bronchocela hayeki (Müller, 1928) (Reptilia: Agamidae) from northern Sumatra Indonesia, Zootaxa 5120 (3), pp. 409-422 : 414-420

Bronchocela hayeki ( Müller, 1928)

( Fig. 4 ; Tables 2 , 3 )

Calotes hayeki Müller, 1928

Calotes hayeki —Brongersma 1931, Wermuth 1967: 38

Bronchocela hayeki — Moody 1980, Manthey & Grossmann 1997: 161, Hallermann 2005, Manthey 2008, Teyni et al. 2010

Holotype. ZSM 3 /1928, collected from Sibayak Plateau (1,400 m above sea level), Berastagi, North Sumatra, Indonesia, by Prof. H. v. Hayek, on April 1, 1927 (lost, fide Hallermann 2005).

Neotype. ZMB 55931, adult male, collected from the foothills of Sibayak (311’N, 9831’E; 1,450 m), Berastagi, North Sumatra, Indonesia, by Ulrich Manthey , in April 1996 (designated by Hallermann 2005) .

Other materials examined. UIMZ 243 , adult male, collected from Paribuan in the Sibayak Plateau (33’14.04”N, 9837’49.74”E; 1,414 m) near Berastagi, Dolok Silau, Simalungun , North Sumatra , by C.A. Putra, D. Arfianto, and P. Sitorus ; MZB 203 , adult male collected from Paya Lueng Kalon (1,260 m), Aceh , by Madzud, on 13 September 1930; ZMH R 05472 and R 05473 (adult males) and ZMH R 05470 (adult female) collected from near Lake Toba (235’N, 9850’E; 1,565 m), North Sumatra ; RMNH 14916 , adult female, collected from Takengon (1,260 m), Aceh ; MZB 8892 and 8893, adult males from Paya Lueng Kalon , Aceh ; MZB 13839 and 13840, adult males from Rainforest Lodges Kedah (1,225 m) , Blang Jerango, Gayo Lues, Aceh .

Diagnosis. A species of Bronchocela inhabiting northern parts of Sumatra Island, Indonesia, characterized as follows: morphologically most similar to its congeners on Sumatra Island, B. cristatella and B. jubata in body colouration, but differs by having the orbital area and the tympanum black (vs. mostly the same as body color in B. cristatella and B. jubata ), enlarged ventral scales arranged in 8 rows (vs. 10–14 slightly-enlarged rows in B. cristatella and 10–12 non-enlarged rows in B. jubata ), well-developed nuchal crest in males (vs. weakly-developed in B. cristatella sensu stricto), higher number of mid body scale rows, 64–75 (vs. 33–59 in B. jubata ). In addition, Bronchocela hayeki is distinguished from other congeners by having the following combination of characters: adults reach maximum SVL 120.0 mm in males and 94.0 in females, 9 or 10 supralabials, 8–12 nuchal crest scales, 50–60 ventrals, 30–33 lamellae on fourth toe, third finger longer than the fourth; dwindled lateral scales directed downward anteriorly and upward posteriorly, 5–7 upper dorsal scale rows on the lateral body directed upward along the body, mid gular scales enlarged, abdominal scales acuminated and enlarged compared to pectoral, non-enlarged and keeled temporal scales with 5–7 rows between orbit and tympanum, tympanum diameter 50–60% of orbit diameter.

Redescription based on UIMZ 0243. An adult male, SVL 117 mm. Head moderately large, elongate, HL 28.8% of SVL, narrow, subtriangular in dorsal and ventral aspects, HW 51.2% of HL; distinct from neck; snout elongate, snout length greater than eye diameter, ED 71.9% of ES; interorbital distance broad; eye large, pupil rounded; diameter of eyes greater than eye-tympanum distance, TYE 68.5% of ED; ear opening shallow, its greatest diameter dorsolaterally, tympanum smaller than orbit, half sized; tympanum surrounded by keeled scales; temporal scales not enlarged, keeled, juxtaposed, 5–7 scale rows between orbit and tympanum; forehead convex; scales on interorbital and supercilium area keeled; scales on snout keeled, larger in size than those of occipital region; a developed nuchal crest continue dorsally as a dorso-nuchal crest; dorsal crest rudimentary, consisting of 12 crescent-shaped scales up to the level of axilla, no crest on the tail; rostral scale width greater than its height, ventroposteriorly in contact with first supralabial, contact posteriorly by five more or less equal-sized postrostral scales; around nostrils on each side two supranasals, two or three postnasals, two prenasals, and two subnasals, which separate nasal from supralabials; nostrils round located middle of the undivided nasal plate; canthus rostralis and supraciliary edges sharp; five canthal scales between supranasal and anterior margin of orbit; no distinct parietal plate; mental subtriangular, shorter than wide, posteriorlaterally in contact with two enlarged postmentals separated by a smaller scale; each postmental pair bordered posteriorly by three smooth scales, including the medial scale, but exclusive of infralabial; chin scales smooth; gular pouch present; throat scales and midgular scales keeled, mucronate, and imbricate; three scale rows separate orbit from supralabials; supralabials nine (seventh in midorbit position); infralabials nine, decreasing in size toward gape; ventral scales on the neck granular and keeled.

Body slender; lateral body scales equal, strongly keeled and imbricate; scales on lateral body much smaller (approximately 1/10 th of mid ventrals) in size than those of venter at same level, directed backward and downward anteriorly and directed backward and upward posteriorly; lateral body scales on the posterior body slights enlarged and shorter than the anterior body scales; 5–7 upper dorsal scale rows directed backward and upward along the body; 69 scales around the midbody; pectoral scales and abdominal scales keeled, acuminated, imbricate and keels forming regular and parallel continuous ventral ridges; abdominal scales larger than pectoral scales; eight scale rows enlarged ventrally, with clear margin with the lateral scales; ventrals, 57.

Forelimbs moderately short; no oblique fold (pit) present on shoulders, but shoulder scales keeled and granular; dorsal scales on fore- and hind limbs keeled, enlarged, imbricate and mucronate; ventral scales on upper arm and lower arm keeled, imbricate, and mucronate; hind limbs relatively longer than forelimbs; scales on ventral surface of thigh keeled, enlarged, imbricate and mucronate; tibia comparatively longer than femur; keels on tibia forming a series of continuous parallel ridges; digits elongate, slender; relative length of digits (fingers) 3> 4> 2> 5> 1; (toes) 4> 3> 5> 2> 1; all bearing slightly recurved claws, claws are sharp and elongate; subdigital lamellae entire, bicarinate, and regular, subdigital lamellae on toe IV (left) 30.

Tail elongate and complete, 412 mm. Ventral scales on tail base keeled and imbricate, smaller in size than on dorsal tail; dorsal scales on tail enlarged, imbricate, keeled, mucronate, and keels forming continuous parallel ridges; tail with subcaudals on median row not enlarged, subequal, imbricate, keeled, and mucronate.

Colouration. In preservative, dorsum pale grayish green; few greyish blue markings on the lateral body; lateral head and nuchal crest scales cream, dorsal head greyish cream; orbit, labial band including the tympanum brown; dorsal crest scales, knee, elbow, wrist, heel grey; dorsal fingers and toes, posterior 2/3 rd of the tail brown; ventral body, limbs, anterior tail, and mid gular pale yellowish green; ventral digits light brown.

In life, dorsum bright luminous green; few sky blue markings on the lateral body; lateral head lemon yellow; nuchal crest blonde yellow, dorsal head greyish green; ventral head bluish green; orbit, labial band including the tympanum blackish brown; dorsal crest luminous green; knee, elbow, wrist, heel dark green; dorsal fingers and toes, posterior 2/3 rd of the tail greenish brown; ventral body, limbs, anterior tail, and mid gular lighter luminous green; ventral digits light brown.

Habitat, natural history, and distribution. This species is usually found in open canopy areas in primary forests (mostly forest edge) or undisturbed secondary forests, but avoids completely open areas. We often found it at the ecotone of forests and other vegetation (e.g. bamboo forests, coffee and pepper plantations, pine forests, wellmaintained home gardens etc.) while basking (from sunrise until midday) on horizontal bamboo sticks or coffee branches, usually 1.5 to 4 meters above the ground. It is usually active during the daytime, mostly around 09:00 hr. At night, the adults prefer higher branches of the tress to sleep, mostly in open canopy areas, while juveniles prefer tiny branches of shrubs. In the Tapanuli area, we sometimes observed this species on Benjamin trees ( Styrax benzoin ; Family Styracaceae ) around 7 m above the ground. The species seems sensitive to being disturbed when approached and when in danger quickly jump to the dense undergrowth and disappear.

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The species is sympatric with other arboreal agamids such as Dendragama boulengeri , Gonocephalus lacunosus , and Bronchocela cristatella . We always found several individuals close together at elevations of 900–1600 m above sea level, and never at elevations lower than 600 m. Most of the individuals were observed at Mt.Paribuan (Simalungun Regency), Mt. Meriah (Deli Serdang Regency), and Mt. Sinabung and Mt. Sibayak (Karo Regency) in North Sumatra. The southern margin of the distribution of this species is the southern parts of Lake Toba, and it seems the distribution records are scattered ( Fig. 1 ) due to forest fragmentation, but always confined to forested uplands. The northernmost distribution is in the Jantho Panorama Park (600 m a.s.l) mostly at the ecotone of the forest and pine plantation.

Conservation status. The forest habitat fragments are further threatened by encroaching agricultural lands, especially large-scale vegetable plantations. We have observed large scale humus soil extraction inside the forest areas around Mt. Paribuan, probably for agricultural use. Such disturbances directly impact the forest system and the population status of the species as they lay their eggs in the humus. Based on our observations, illegal pet trade has been identified as one of the major threats. The application of the IUCN Red List criteria ( IUCN Standards & Petitions Subcommittee 2019) with the updated distribution data shows that B. hayeki is restricted to an area of occupancy (AOO) of 144 km 2 recorded from 13 localities (eight locations) within 52, 857 km 2 extent of occurrence (EOO). Given the low area of occupancy, the scattered distribution of severely fragmented forests, B. hayeki should be considered as an “Endangered” (EN) species.

Figures

FIGURE 1. Current distribution map showing the collection/observation localities of Bronchocela hayeki (yellow) on Sumatra Island, its sympatric congener, B. cristatella sensu lato (blue) and allopatric congener B. jubata sensu lato (red) also indicated on the map; sympatric localities filled partially

FIGURE 4. Bronchocela hayeki in life (UIMZ 0243, adult male): (A) lateral view of the full body, (B) dorsal head, (C) lateral head, (D) ventral head, and (E) secondary forest habitat collected from near the type locality.