Lepidodactylus sacrolineatus, Kraus & Oliver, 2020

Kraus, Fred & Oliver, Paul M., 2020, A new species of Lepidodactylus (Squamata: Gekkonidae) from the mountains of northeastern Papua New Guinea: older than the hills, Zootaxa 4718 (4), pp. 549-561 : 551-555

Lepidodactylus sacrolineatus sp. nov.

Figs. 1A , 2

Lepidodactylus magnus (part) Brown & Parker, 1979: 258.

Lepidodactylus sp. Bundi Oliver et al., 2018: 4.

Holotype.― BPBM 34737 (field tag FK 13703 ), mature male, obtained by F. Kraus at Keki Lodge, 4.7048°S, 145.4042°E ( WGS 84 ), 850 m a.s.l., Adelbert Mts. , Madang Province, Papua New Guinea (PNG), collected 30 September 2009.

Paratypes (n = 4).― Males : Bundi, E slope Mt. Wilhelm, 5.74°S, 145.23°E, 1340 m a.s.l., Madang Province, PNG, collected 23 April 1987 by T . Reardon ( AMS R124447 , R124492 ); Lalang , Cromwell Mts., 6.33°S, 147.42°E, 1400 m a.s.l., Morobe Province, PNG, collected 26 July 1964 by H.M. van Deusen ( AMNH 95655 ) . Females: Bundi, E slope Mt. Wilhelm, 5.74°S, 145.23°E, 1340 m a.s.l., Madang Province, PNG, collected 23 April 1987 by T . Reardon ( AMS R124492 ); Ebabaang , Hube Area, 6.4931°S, 147.4632°E, 1160 m a.s.l., Morobe Province, PNG, collected 15 April 1955 by E.O. Wilson ( MCZ 54246) .

Diagnosis.―A large species of Lepidodactylus (adult SVL 52–60 mm); tail subcylindrical; all terminal and subterminal lamellae entire; 38–47 enlarged scales of pore-bearing series divided into a precloacal series separated by 9–12 scales from each femoral series, 30–40 precloacal/femoral pores in males (9–12 precloacal, 8–14 femoral); 11–13 T 4 lamellae, 8–10 T 1 lamellae; moderately wide toes ( T 4W/ T 4L = 0.27–0.30); toes with only basal webbing ( T 3 T 4webL/ T 4L = 0.11–0.17, T 4 T 5webL/ T 4L = 0.05–0.13); dorsum with scattered dark-brown spots concentrated mid-dorsally; area above tail base and hindlimb insertion with pale tan vertebral line whose posterior end flares laterally; and many posteroventral and plantar scales uniformly brown.

Comparisons with other species.―The subcylindrical tail and series of undivided lamellae under all toes place Lepidodactylus sacrolineatus sp. nov. in Brown & Parker’s (1977) phenetic Group I. The new species differs from all other Melanesian members of Group I except L. magnus Brown & Parker in having a high-contrast, well-demarcated vertebral line above the sacral region; some other members of this group may have the suggestion of such a line but it is never clearly delineated by a dark lateral margin, nor so long, and it is often interrupted by encroachment of banding from the sides. Lepidodactylus sacrolineatus sp. nov. further differs from other Melanesian Group I members as follows: from L. browni Pernetta & Black and L. orientalis Brown & Parker in having the pore series in males divided into three distinct groups, with one precloacal series and an additional series on each thigh (versus having only the precloacal series in L. browni and L. orientalis ); and dorsum with few dark-brown spots concentrated mid-dorsally (versus dorsum with brown saddles in L. browni and L. orientalis ). The new species differs from L. aignanus Kraus in its much larger size ( SVL = 52–60 mm versus 37.5 mm in L. aignanus ) and in having 38–47 enlarged precloacal/femoral scales distributed in three series (versus 17 enlarged scales comprising only a precloacal series in L. aignanus ), only basally webbed toes ( T 3 T 4webL/ T 4L = 0.11–0.17 versus 0.26 in L. aignanus ), and dorsum with few dark-brown spots concentrated mid-dorsally (versus with brown saddles and many pale lateral and dorsolateral round spots in L. aignanus ); from L. mutahi Brown & Parker in its larger size (male SVL = 57–60 mm versus 37–56 mm in L. mutahi , female SVL = 52–57 mm versus 43–50 mm in L. mutahi ), its tripartite precloacal/ femoral pore series (versus a single continuous series in L. mutahi ), slightly higher number of precloacal/femoral pores (30–40 versus 27–34), and less toe webbing ( T 3 T 4webL/ T 4L = 0.11–0.17 versus ~ 0.25 in L. mutahi ); from L. pumilus in its larger size ( SVL = 52–60 mm versus 34–48 mm in L. pumilus ), less toe webbing ( T 3 T 4webL/ T 4L = 0.11–0.17 versus 0.18–0.19 in L. pumilus ) especially between T 4 and T 5 ( T 4 T 5webL/ T 4L = 0.05–0.13 versus 0.23 in L. pumilus ), and its gray dorsum with few dark-brown spots concentrated mid-dorsally (versus uniformly pale red-brown dorsum in L. pumilus ); from L. zweifeli Kraus in its considerably larger adult size ( SVL = 52–60 mm versus 41–44.5 mm in L. zweifeli ), femoral pore series separated by 9–12 scales from precloacal series (versus 2–3 scales in L. zweifeli ), enlarged scales present on thighs (versus absent in L. zweifeli ), and wider digits ( T 4W/ T 4L = 0.28–0.30 versus 0.24–27 in L. zweifeli ).

The new species is most similar to L. magnus , from which it differs in its smaller size (mean SVL = 56.7 mm, range = 52–60 mm, SD = 1.30 versus mean = 64.8 mm, range = 56.5–69.5 mm, SD = 1.86 in L. magnus ) and in having the precloacal/femoral pores in three widely separated series separated by 9–12 scales (versus usually in a single series in L. magnus but may have one or a few scales disrupting the series); enlarged chin shields usually in 2–3 pairs posterior to the mental (versus a single pair followed by irregular smaller scales in L. magnus ); no dark stripe above arm or behind eye (versus present in L. magnus ); and dark dorsal spots fewer, largely concentrated mid-dorsally (versus many dark spots that are mostly lateral in L. magnus , and dorsum banded in life in L. magnus , Fig. 1B, C ). Though both species have a pale vertebral line above the tail base and hindlimb insertion, that of L. sacrolineatus sp. nov. differs from that in L. magnus in having its posterior end widely flared laterally and in being of higher contrast with the surrounding coloration. In contrast, the condition seen in L. magnus is for this line to be the same width posteriorly as across the remainder of the stripe, although AMS R 16603 has the posterior end slightly flared, though not so much as seen in L. sacrolineatus sp. nov. And the line in L. magnus is of less contrast with the surrounding color than seen in L. sacrolineatus sp. nov. ( Fig. 1 ).

Description of holotype.―A mature male, with right-lateral incision.Animal large ( SVL = 57.0 mm, TrL = 27.5 mm). Head relatively long ( HL / SVL = 0.26) and wide ( HW / HL = 0.82), much wider than neck ( Fig. 2A ). Loreal region distinctly inflated; no canthus rostralis. Interorbital region and top of snout shallowly concave. Snout tapered and rounded at tip, relatively long ( SN / HL = 0.45), almost twice eye diameter ( SN / EY = 1.9). Eye relatively large ( EY / HL = 0.23, EY/ EN = 0.65); pupil vertical, constricted into series of four lobes ( Fig. 2B ); supraciliaries approximately twice size of adjacent granules. Ear opening small (Ear/ HL = 0.075), tetrahedral shaped, with longer axis oriented slightly diagonally from posterodorsal to anteroventral; distance between ear and eye larger than eye diameter ( EE / EY = 1.4). Rostral wider (2.6 mm) than high (1.4 mm), highest just medial to nares, lower between these points; length (0.6 mm). Supranasals separated by three internasals. Rostral in contact with first supralabials, two supranasals, and three internasals. External nares circular; each bordered by rostral, two supranasals, first supralabial, and one postnasal. Mental shallowly triangular, slightly shorter (1.0 mm) than wide (1.3 mm). Mental bordered posteriorly by two slightly enlarged postmentals, these bordered posteriorly by progressively smaller scales prior to granular chin scales. Infralabials also bordered by enlarged scales that gradually decrease in size posteriorly. Supralabials to mid-orbital position ten on each side; infralabials 11 on right, 12 on left.

Body of modest habitus (TrL/ SVL = 0.48), fairly depressed. Dorsal scales on head and body tiny juxtaposed granules; tubercles absent. Ventral scales flat and smooth; those on throat smaller and juxtaposed; those on abdomen larger and subimbricate, gradually decreasing in size laterally and on chin to become granular. Scales on limbs flat, subimbricate.

Enlarged precloacal scales 12, in a short series forming a shallow chevron. Enlarged scales on thighs smaller than those of the precloacal series, separated from precloacal series by seven scales on right and eight on left. Enlarged scales also form a pubic patch between the precloacal series and the vent; no tiny scales between the precloacal series and this pubic patch; ten rows of scales between enlarged precloacal series and vent. Scales on palms and soles rounded, smooth.

Fore- and hindlimbs relatively well-developed ( FA / SVL = 0.12, CS / SVL = 0.14). Digits well-developed, moderately dilated throughout their length ( T 4W/ T 4L = 0.30), all but first fingers and toes with recurved claws ( Fig. 2C, D ); clawed phalanges laterally compressed, free above and extending slightly beyond terminal lamellae. Subdigital lamellae narrow and smooth, all undivided but several are notched; lamellae extend for more than half length of each toe ( T 4lamellaeL/ T 4L = 0.58). Lamellae of manus 9–9–12–10 –9 on right, 9–9–11–13 –9 on left; of pes 10–10– 11–12–9 on right, 9–11–12–12 –9 on left. Relative lengths of digits on manus and pes I <II < V <III <IV. Webbing present between all digits; toes less than one-quarter webbed ( T 3 T 4webL/ T 4L = 0.17)

Tail entire, long ( TL / SVL = 1.17), relatively wide ( TW / SVL = 0.10); lateral margins without skin flanges or spines. Scales of tail small, flat, smooth, subimbricate, smaller dorsally; two small postcloacal spurs on sides of tailbase.

Color in preservative: Dorsal ground color dark brown, paler on tail. Dorsum with few small dark-chocolatebrown spots, these largely arrayed in a vertebral series of six spots larger anteriorly than posteriorly and two largely dorsolateral series comprising only one or two granules/spots; a few small pale-tan spots present laterally anterior to forearm insertions and also forming sparse series in dorsolateral regions. Base of tail with short tan vertebral stripe beginning just posterior to cloacal sac, ending near anterior end of hindlimb insertion, expanded laterally at its posterior end and merging into same tan color of tail, margined laterally with dark chocolate brown. Tail with few obscure darker-brown bands. Short tan postocular stripe with length approximately half eye diameter, this followed by small spot of same color, both partially margined with dark chocolate brown ( Fig. 2B ). Labials tan punctated with brown, giving the appearance to the naked eye of being brown with large tan spots ( Fig. 2B ). Two narrow dark-chocolate-brown markings between eye and supralabials oriented with long axis in anterior-posterior direction. Venter tan, each scale punctated with brown, imparting overall appearance of pale-brown venter to naked eye. Palmar and plantar surfaces same, but lamellae tend toward grayish brown. Iris silver heavily veined with black.

Color in life: Dorsal ground color gray brown with a series of darker gray-brown mid-dorsal spots and with a tan vertebral line having posterior lateral rami above the insertion of the hind legs. Venter dirty brown with reddish cast. Iris pale copper-brass ( Fig. 1A ).

Measurements (in mm). – SVL = 62.0 (in life) and 57.0 (in preservative), TL = 72.5, TrL = 27.5, TW = 5.6, FA = 6.6, CS = 7.8, HL = 14.7, HW = 12.0, Ear = 1.1, EE = 4.7, EY = 3.4, SN = 6.6, EN = 5.2, IN = 2.8, T 4L = 6.6, T 4W = 1.95, T 4lamellaeL = 3.8, T 3 T 4webL = 1.1, T 4 T 5webL = 0.6, mass = 3.85 g.

Variation.―Mensural differences are minor ( Table 1 ). Numbers of T 4 lamellae on the toes vary from 11–13, and T 1 lamellae from 8–10. The numbers of pores in males vary from 9–12 for the precloacal series and from 11–13 in the femoral series. AMS R 124447 is an exception to the latter inasmuch as the femoral series are broken up by intruding smaller scales; this specimen has, from right to left, a femoral/precloacal series of 7–1– 11–7–3–1 pores. The series of enlarged precloacal and femoral scales reflect these patterns but are generally of greater number, varying from 38–47. Enlarged femoral scales are especially difficult to count for females, who lack the pores that make these scales easier to determine in males. Of the two females, AMS R 124492 appears to have 14–10–18 enlarged scales in this series, and MCZ 54246 has 14–12–15.

There is minimal variation in color pattern in the type series. AMS R124447 is similar to the holotype in degree of dark dorsal spotting but shows no evidence of the pale postocular stripe and dot; AMS R124492 and AMNH 95655 have more dorsolateral dark spotting than does the holotype. AMS R124492 has the postocular stripe and dot connected to form a single longer line; that of AMNH 95655 is faded but similar in extent to that seen in the holotype. AMS R124492 and AMNH 95655 have a number of small dark-chocolate-brown markings on the head, including an interorbital bar and a line in the loreal region (right side only for AMS R124492 ) . AMS R124447 has the vertebral stripe in the sacral region somewhat less conspicuous than do the other specimens. All paratypes are more faded than the holotype, having been collected 22–54 years earlier. All paratypes have the same paler venter as seen in the holotype. The irises of all paratypes appear dark brown.

Genetics.―Based on analyses of the ND2 mitochondrial gene, L. sacrolineatus sp. nov. is most similar to L. magnus ( Fig. 3 ); however, it is highly divergent from even that species (p-distances between 0.28–0.29). Intraspecific genetic divergence between L. sacrolineatus sp. nov. samples from the type locality in the Adelbert Ranges (n = 1) and Bundi (n = 2) are comparatively low (p-distances 0.055 –0.056).

Etymology.―The species name is a masculine compound adjective derived from the Latin os sacrum, in reference to the fused vertebral bone between the hindlimbs, and linea, or line. The name is in reference to the distinctive marking this species has in the sacral region.

Range.― Known from three separate mountain ranges of northeastern New Guinea: the northern edge of the Central Highlands (Madang Province), the Adelbert Mountains (Madang Province), and the eastern end of the Saruwaged Mountains on the Huon Peninsula (Morobe Province). Known localities span elevations from 850–1400 m a.s.l. ( Fig. 4 ).

Ecology.―The holotype was taken with a sticky trap stapled approximately 2 m above the ground to the trunk of a large Areca palm standing in a small clearing surrounded by primary rainforest. Continued efforts to obtain other animals on this and nearby trees failed, suggesting that the species is either uncommon, usually an inhabitant of forest, or rarely approaches the ground. The two paratypes from Bundi were brought into the village by local collectors and no habitat data are available.

Remarks.―The specimens from the Huon Peninsula ( AMNH 95655, MCZ 54246) were included in the type series of L. magnus by Brown and Parker (1977), but they have all the scalational and color-pattern features of the new species. Lepidodactylus sacrolineatus sp. nov. is geographically allopatric to L. magnus , though the two species approach within 40 km of each other ( Fig. 4 ) on opposite sides of the intervening Mt. Wilhelm, which reaches 4500 m elevation.

Figures

FIGURE 1. Portraits in life of (A) holotype of Lepidodactylus sacrolineatus sp. nov. (BPBM 34737), Adelbert Mts.; (B) paratype of L. magnus (MCZ 91588), Yandime; and (C) paratype of L. magnus (uncertain AMNH specimen), Ubaigubi. Photos (A) F. Kraus, (B) and (C) F. Parker.

FIGURE 2. (A) Top of head, (B) side of head, (C) palmar view of left hand, and (D) plantar view of left foot of Lepidodactylus sacrolineatus sp. nov. (BPBM 34737). Scale for (A) and (B) is 10 mm; that for (C) and (D) is 5 mm.

FIGURE 3. Bayesian chronogram for Lepidodactylus and allied genera estimated from two nuclear genes (modified from figure S3 in Oliver et al., 2018). The Lepidodactylus pumilus group is highlighted in light grey; timeframe in millions of years ago.

FIGURE 4. Map of eastern Papua New Guinea showing collecting localities for Lepidodactylus sacrolineatus sp. nov. (squares) and L. magnus (circles), with which it was previously confused. Type localities are solid symbols; other localities are open symbols.