Hemiphyllodactylus engganoensis, Grismer, L. Lee, Riyanto, Awal, Iskandar, Djoko T. & Mcguire, Jimmy A., 2014

Grismer, L. Lee, Riyanto, Awal, Iskandar, Djoko T. & Mcguire, Jimmy A., 2014, A new species of Hemiphyllodactylus Bleeker, 1860 (Squamata: Gekkonidae) from Pulau Enggano, southwestern Sumatra, Indonesia, Zootaxa 3821 (4), pp. 485-495 : 487-494

Hemiphyllodactylus engganoensis sp. nov.

Pulau Enggano Dwarf Gecko Cicak Kerdil Enggano

Figs. 3 , 4

Holotype. Adult female ( MZB.Lace 4568) collected at 2220 hours on 11 May, 2013 by Jimmy A. McGuire, Djoko T. Iskandar, Awal Riyanto, and Mulyadi near the village of Malakoni on the island of Enggano (Kecamatan Enggano, Kabupaten Bengkulu, Propinsi Bengkulu, Indonesia; S 0 5.35290, E 102.27742, 1 m elevation).

Paratype. Subadult female ( MVZ 239345) and adult male ( MVZ 239346) bear the same collection data as the holotype.

Diagnosis. Hemiphyllodactylus engganoensis sp. nov. is differentiated from all other congeners by having the unique combination of a maximum SVL of 37.3 mm; six chin scales; no enlarged postmentals; five circumnasal scales; three or four scales between the supranasals; 12 supralabials; 24 or 25 dorsal scales; 14 ventral scales; a lamellar hand formula of 4554 or 4454; a lamellar foot formula of 4555; four or five subdigital lamellae on the first finger; four or five subdigital lamellae on the first toe; a contiguous femoroprecloacal pore series of 42; five cloacal spurs in males; no enlarged subcaudal scales; no dark postorbital stripes or striping on body; small dark blotches on dorsum; a yellowish postsacral mark bearing anteriorly projecting arms; and a pigmented caecum and gonads. (Table 1).

Description of holotype. Adult female; head triangular in dorsal profile depressed, distinct from neck; lores and interorbital regions flat; rostrum relatively long (NarEye/ HeadL = 0.30); prefrontal region flat to weakly concave; canthus rostralis smoothly rounded, barely discernable; snout moderate, rounded in dorsal profile; eye large; ear opening oval, small; eye to ear distance greater than diameter of eye; rostral wider than high, partially divided dorsally, bordered posteriorly by large supranasals; three internasals (=postnasals); external nares bordered anteriorly by rostral, dorsally by supranasal, posteriorly by two postnasals, ventrally by first supralabial (collectively the circumnasals 5 R, L); 12 (R, L) square supralabials tapering to below posterior margin of orbit; 12 (R, L) square infralabials tapering to below posterior margin of orbit; scales of rostrum and lores, raised; scales on top of head and occiput small, granular; dorsal superciliaries raised, rectangular; mental triangular, bordered laterally by first infralabials and posteriorly by two non-enlarged postmentals; each postmental bordered laterally by a single sublabial; row of smaller scales extending transversely from juncture of second and third infralabials and contacting mental; gular scales triangular, small, granular, grading posteriorly into slightly larger, subimbricate throat and pectoral scales which grade into slightly larger, subimbricate ventrals.

Body elongate, dorsoventrally compressed; ventrolateral folds absent; dorsal scales small, granular, 25 scales contained within one eye diameter; ventral scales flat, subimbricate, much larger than dorsal scales, 14 scales contained within one eye diameter; no enlarged, precloacal scales; no pore-bearing scales femoral or precloacal scales; forelimbs short, robust in stature, covered with granular scales dorsally and slightly larger, flat, subimbricate scales ventrally; palmar scales flat, subimbricate; all digits except digit I well-developed; digit I vestigial, clawless; distal, subdigital lamellae of digits II–V divided, angular and U-shaped; lamellae proximal to these transversely expanded, undivided; lamellar formula of digits II–V 4-4 -5-4 (R, L); four transversely expanded lamellae on digit I; claws on digits II–V well-developed, unsheathed; distal portions of digits strongly curved, terminal joint free, arising from central portion of lamellar pad; hind limbs short, more robust than forelimbs, covered with slightly pointed, juxtaposed scales dorsally and by larger, flat, subimbricate scales ventrally; plantar scales low, flat, subimbricate; all digits except digit I well-developed; digit I vestigial, clawless; distal, subdigital lamellae of digits II–V divided, angular and U-shaped; lamellae proximal to U-shaped lamellae transversely expanded, undivided; lamellar formula of digits II–V 4-5 -5-5 (R, L); five transversely expanded lamellae on digit I; claws on digits II–V well-developed, unsheathed; distal portions of digits strongly curved, terminal joint free, arising from central portion of lamellar pad; all caudal scales flat, imbricate, not occurring in caudal segments, no enlarged subcaudals. Morphometric data are presented in Table 2 .

Coloration in alcohol. Top of head, body and limbs nearly unicolor tan; ground color of dorsal surface of tail tan bearing nine, dark-colored, diffuse bands; lores slightly darker; no postorbital striping; faint, diffuse lightcolored spots on dorsum barely discernable; light-colored, postsacral marking bearing faint, anteriorly projecting arms; ground color of gular region beige with small, dark-brown spots; ground color of ventral surfaces of body and limbs beige, immaculate; dorsal coloration invades lateral sections of abdomen.

Variation. The paratype MVZ 239345 approaches the holotype in general dorsal coloration and pattern ( Fig. 3 , 4 ). In life, the dorsal ground color of the head is dull-yellow and that of the body, limbs, and tail is tan with faint, darker bands. All dorsal surfaces are overlain with a reticulum of darker markings that tend to form thin, zig-zag lines across the body and wider bands on the tail. The light-colored, postsacral marking is more vivid. The iris is silver. The tail is complete, original, and round in cross-section ( Fig. 4 ). The male paratype MVZ 239346 is missing a tail and has a uniform tan dorsal ground color ( Fig. 4 ). It also has a continuous series of 42 femoroprecloacal pores and five cloacal spurs, both of which are lacking in the two female specimens. Differences in meristics and morphometrics are listed in Table 2 .

MZB.Lace MVZ MVZ Distribution. Hemiphyllodactylus engganoensis sp. nov. is known only from the type locality near the village of Malakoni on the island of Enggano. We presume it to be endemic to the entire island, though it may be restricted to Enggano’s coastal perimeter. All three specimens in the original series were collected within a few hundred meters of one another in beachside vegetation.

Natural history. The three specimens of Hemiphyllodactylus engganoeneis sp. nov. were collected where lowland forest habitat interfaced with a sandy beach near the mouth of a small river along the Enggano coastline. The holotype was collected approximately 1 m above the ground on the leaf of a sapling, and the two paratypes were collected about 1 m above the ground on and between Pandanus leaves. The specimens were all collected between 2200 and 2225 hrs. Pandanus was abundant along the forest edge, and the crevices between its serrated, strap-shaped leaves were also inhabited by two other gecko species, Lepidodactylus lugubris (Duméril & Bibron) and Hemidactylus frenatus Schlegel.

Etymology. The specific epithet engganoensis is an adjective in reference to the type locality Pulau Enggano, Bengkulu Province, Indonesia.

Comparisons. The taxonomy of Grismer et al. (2013, 2014), Ngo et al. (2014); Nguyen et al. (2013), and Zug (2010) is used in the comparisons below for H. titiwangsaensis Zug, H. typus Bleeker and H. yunannensis (Boulenger) . Hemiphyllodactylus engganoensis sp. nov. is one of the smallest species of the genus and differs from H. banaensis Ngo, Grismer, Thai , & Wood; H. chiangmaiensis Grismer, Wood , & Cota; H. larutensis (Boulenger) ; H. margarethae Brongersma ; H. titiwangsaensis Zug; H. typus Bleeker ; H. yunnanensis ; and H. zugi Nguyen, Lehmann, Le Duc, Bonkowski , & Ziegler by its maximum SVL of 37.3 mm vs a SVL>41.0 mm. Its postmentals are not distinctly enlarged which separates it from H. banaensis , H. chiangmaiensis ; H. harterti (Werner) ; H. larutensis ; H. margarethae ; H. titwangsaensis ; H. typus ; H. yunnanensis ; H. tehtarik Grismer, Wood, Anuar, Muin, Quah, McGuire, Brown, Ngo, & Thai; and H. zugi . Hemiphyllodactylus engganoensis sp. nov. can be differentiated from H. banaensis , H. larutensis , H. titwangsaensis , and H. zugi by having five vs. two or three circumnasal scales. It differs from all other species except H. zugi in having 24 or 25 dorsal scales (as opposed to having fewer than 22) and having 14 ventral scales separates it from H. banaensis , H. aurantiacus (Beddome) , H. chiangmaiensis , H. ganoklonis Zug, H. margarethae , H. titwangsaensis , H. yunnanensis , and H. tehtarik which have 12 or less. Hemiphyllodactylus engganoensis sp. nov. has a unique lamellar formula on the hand (4-5-5-4 or 4-4-5-4) that separate if from all other species except H. banaensis that have various other combinations (see Table 1). Having a series of femoral and precloacal pores that are not contiguous separates H. engganoensis sp. nov. from H. aurantiacus , H. ganoklonis , H. insularis Taylor, H. margarethae , some H. typus , and H. yunnanensis which all have a contiguous pore series. Additionally, having a total pore count of 42 further differentiates H. engganoensis sp. nov. from all other species (except H. harterti ) who have less than 40 (0–39 collectively). Hemiphyllodactylus engganoensis sp. nov. has a high number (5) of cloacal spurs which at least distinguishes it from H. auratiacus , H. banaensis , H. harterti , H. insularis , H. larutensis , H. margarethae , H. yunnanaensis , and H. zugi which collectively have 0–3 cloacal spurs. There are a number of morphometric ratios concerning various structures that are potentially diagnostic (Table 1). However, due to the incomplete sample sizes across all age classes for all species, we consider their diagnostic utility as tentative at this point. Additionally, H. engganoensis sp. nov. is possibly separated from various other species on the basis of a number color pattern characters (Table1). However, because the color variation in the type series (three specimens) is extensive ( Fig. 3 ), we defer judgment as to the utility of these characters as well until the acquisition of additional material. Based on the mitochondrial ND2 gene, Grismer et al. (2013) noted that H. engganoensis sp. nov. has an uncorrected sequence divergence of 17.5% from its closest relative from Pulau Sibu, Malaysia.

Figures

FIGURE 3. Paratype MVZ 239345 (subadult female) of Hemiphyllodactylus engganoensis sp. nov. from Pulau Enggano, Indonesia.

FIGURE 4. Type series of Hemiphyllodactylus engganoensis sp. nov from Pulau Enggano, Indonesia. Upper: holotype MZB. Lace 4568 (adult female). Middle: paratype MVZ 239346 (adult male). Lower: paratype MVZ 239345 (subadult female).

Tables

TABLE 2. Scale counts, color pattern characteristics, and morphometric ratios of the type series of Hemiphyllodactylus engganoensis sp. nov. (variable features only).

	4568	239345	239246
	holotype	paratype	paratype
Sex	f	f	m
SVL	34.6	30.6	37.3
dorsal scales	25	25	24
ventral scales	14	14	15
lamellar formula on hand	4-4-5-4	4-5-5-4	4-4-5-4
subdigital lamellae on first toe	5	5	4
dark dorsal transverse blotches	very faint	faint	absent
Trunk/SVL	0.47	0.51	0.49
HeadL/SVL	0.25	0.26	0.24
HeadW/SVL	0.16	0.16	0.16
HeadW/HeadL	0.62	0.62	0.67
SnEye/HeadL	0.41	0.41	0.43
NarEye/HeadL	0.30	0.29	0.3
EyeD/HeadL	0.24	0.24	0.23
SnW/HeadL	0.14	0.15	0.13
EyeD/NarEye	0.80	0.82	0.77
SnW/HeadW	0.22	0.24	0.2
SVL	34.6	30.6	37.3
trunk	16.4	15.7	18.3
HeadL	8.7	7.9	8.9
HeadW	5.4	4.9	6
SnEye	3.6	3.2	3.8
NarEye	2.6	2.3	2.7
EyeD	2.1	1.9	2.1
SnW	1.2	1.2	1.2
TaiL	30.0	/	28.3