Plestiodon takarai, Kurita, Kazuki, Ota, Hidetoshi & Hikida, Tsutomu, 2017

Kurita, Kazuki, Ota, Hidetoshi & Hikida, Tsutomu, 2017, A new species of Plestiodon (Squamata: Scincidae) from the Senkaku Group, Ryukyu Archipelago, Japan, Zootaxa 4254 (5), pp. 520-536 : 526-533

Plestiodon takarai sp. nov.

( Fig. 3 )

Eumeces elegans: Takara 1954 , p. 69; Ikehara & Shimojana 1971, p. 91; Hikida 1979, p. 42 (part); Hikida 1993, p. 2 (part); Ota et al. 1993, p. 250; Zhao & Adler 1993, p. 210 (part); Hikida 1996, p. 80 (part); Hikida 2002, p. 209 (part); Uchiyama et al. 2002, p. 231 (part); Goris & Maeda 2004, p. 161; Ota 2004, p. 37; Lin 2007, p.34 (part).

Plestiodon elegans: Maenosono & Toda 2007 , p. 39; Matsuhashi & Tomita 2007, p. 105 (part); Otani 2009, p. 205 (part); Shang et al. 2009, p. 208 (part); Yokohata et al. 2009, p. 311; Takada & Ohtani 2011, p. 109 (part); Ota 2014, p. 18; Seki 2016, p. 98 (part).

Holotype. KUZ R32170, an adult female from Kitakojima Island in the Senkaku Group , collected on 16 June 1995 by H. Ota.

Paratypes. One adult and two yearling males, and one adult and one yearling females from Uotsurijima Island: RUMF-ZH-00862 collected on 16 April 1952 by T. Takara; KUZ R18921 – 24 collected in late May 1979 by S. Ikehara. One adult and four subadult males, and three adult and one subadult female from Kitakojima Island: KUZ R32162 – 69, R35252 (the same collection data as the holotype). One subadult and one hatchling male from Minamikojima Island: OPM-H-560 collected on 12 September 1974 (collector unknown) ; KUZ R18077 collected on 25 May 1991 by N. Sakaguchi. Three adult males from Kubajima Island : KUZ R39041–43 collected on 26 May 1991 by N. Sakaguchi.

Diagnosis. Plestiodon takarai is assigned to the P. latiscutatus species group (sensu Hikida 1993) based on the presence of a fan-shaped upper secondary temporal scale with an emarginated posterior margin and keeled postanal scales. This species differs from the other members of the P. latiscutatus species group excluding P. elegans (i.e., P. latiscutatus ; P. marginatus ; P. japonicas [ Peters, 1864]; P. oshimensis ; P. stimpsonii ; P. barbouri [ Van Denburgh, 1912a]; P. finitimus Okamoto & Hikida, 2012 ; and P. kuchinoshimensis ) by having EISPF (EISPF absent in the latter eight species of this species group).

Morphologically, P. takarai is most similar to P. elegans . However, it differs from this species in terms of the MSR, TIV, SL-PL, APF, and tail coloration of hatchlings ( Table 5; Fig. 4 ). Plestiodon takarai can be distinguished from P. elegans from continental China in having a larger number of MSR (range = 26–29 [mean ± SD = 27.8 ± 0.6, n = 20] vs. 24–28 [usually 26] in P. elegans from the continent [ Van Denburgh 1912b; Taylor 1936; Dong 1991; Huang, 1999]), a larger number of TIV (range = 18–24 [mean ± SD = 21.3 ± 1.4, n = 20] vs. usually less than 18 in P. elegans from the continent [ Van Denburgh 1912b; Dong 1991; Huang 1999]), the posterior loreal that is contact with usually three SL (40–67% vs. mostly two SL [90%] in P. elegans from the continent [ Hikida 1989]), and prefrontal scales that is separate (100% vs. usually in contact [60%] in P. elegans from the continent [ Van Denburgh 1912b]). Plestiodon takarai differs from P. elegans from Taiwan in having a larger number of MSR (more than 26 vs. usually less than 26 in P. elegans from Taiwan [ Stejneger 1907; Van Denburgh 1912b]). Plestiodon takarai further differs from P. elegans from the Penghu Group in having a larger number of MSR (more than 26 vs. less than 26 in P. elegans from the Penghu Group [ Stejneger 1907; Van Denburgh 1912b]), the posterior loreal that is contact with usually three SL (40–67% vs. mainly two SL [71%] in P. elegans from the Penghu Group), and a larger number of TIV (more than 18 vs. less than 18 in P. elegans from the Penghu Group [ Van Denburgh 1912b]). In addition to these differences in scutellation, P. takarai is also distinct from P. elegans in hatchling tail coloration (light blue in the distal half and dark gray or tan in the proximal half vs. dark brilliant blue or violet in the whole tail [ Zhao & Adler 1993; Kato & Ota 1994; Ota 2004] or blue in the distal half and greenish blue in the proximal half [K. Kurita and T. Hikida, personal observation] in P. elegans ).

Description of holotype. Adult female, SVL = 70.9 mm; tail regenerated (TaL = 95.1 mm including 42.4 mm of regenerated portion). Other measurements are given in Table 6.

Snout rounded; rostral partly visible from above, about as wide as high, overlapping supranasals, nasals, and first supralabial; pair of supranasals as large as prefrontals, contacting each other, overlapped by nasals; frontonasal about as wide as long, overlapped by supranasals and anterior loreal (only on left side), overlapping prefrontals and frontal; pair of prefrontals slightly smaller than frontoparietals, separated from each other, overlapped by anterior and posterior loreals, overlapping first supraciliary, first supraocular, and frontal; frontal large, much longer than its distance from tip of snout, narrower slightly posteriorly, overlapping first to third supraoculars, and frontoparietals; four supraoculars on each side, anterior ones overlapping posterior ones, first one overlapped by first to third supraciliaries, second one overlapped by third to sixth supraciliaries, third one overlapped by sixth and seventh supraciliaries, fourth one overlapped by seventh and eighth supraciliaries; pair of frontoparietals about as wide as long, left one overlapping right one anteriorly, overlapped by third and fourth supraoculars, overlapping parietals and interparietal; interparietal more than twice as long as wide, narrowed posteriorly, rounded behind, overlapping both parietals and nuchals; pair of parietals large, as long as interparietal, wider than frontal, overlapped by fourth supraocular and two pretemporals, overlapping upper secondary temporal and nuchal; pair of nuchals, left one overlapped by right one, right one divided into left and right parts.

Values from the left anđ right siđes are combineđ in TΙV for P. takarai sp. nov.

Locality MSR TΙV Source

N Mean Range N Mean Range

takarai sp. nov. Uotsurijima Ιslanđ 5 27.8 27M 28 5 2 Ɵ.I I8 M22 This stuđy elegans Continental China 264 26.5 25M28 ― ― ― Taylor (I936) Holotype

Type (KUZ Paratypes

R 32I7 Ɵ)

Kitakojima

Locality Uotsurijima Ιs. Kitakojima Ιs. Minamikojima Ιs. Kubajima Ιs. Ιs.

Age Ađult Ađults Yearlings Ađults Subađults Subađult Hatchling Ađults

Female Female

Sex (n) Female Male (I) Male (2) Male (I) Female (3) Male (4) Female (I) Male (I) Male (I) Male (3)

(I) (I)

SVL 7Ɵ.9 ― 67.Ɵ 35.Ɵ, 4Ɵ.2 38.5 75.9 7Ɵ.9± I.4 59.9±4.5 54.8 66.5 34.7 7Ɵ.7± I.4 (69.5M72.8) (54.ƟM65.6) (69.6M72.6)

TaL 95.I a I4.7+75.Ɵ c 83.6a 34.5, 45.3b 54.7a I22.8b 9 I.5 ±I7.3 63.8±28.5 5I. 8a 7Ɵ.8+ II.3 ac 4Ɵ.8b 53.6±29.Ɵ (68.4MIIƟ.3)đ (I4.5M82.Ɵ)đ (I2.9M78.8)đ

MDCSL Ɵ.Ɵ Ɵ.Ɵ ― ―, 25.Ɵ 25.Ɵ Ɵ.Ɵ Ɵ.Ɵ Ɵ.Ɵ I 6.3e Ɵ.Ɵ 27.9 Ɵ.Ɵ

AGL 35.9 ― 36.Ɵ I8.6, 2Ɵ. 2 I 9.8 37.2 36.8±I. I 3 Ɵ.2±2.8 28.7 32.6 I9.8 35.7±2.4 (35.3M37.7) (26.4M33.I) (33.8M39.I)

SFL 24.I 2I.8 22.I I 3.I, I5.4 ― 25.9 22.8± 2.I I9.8± I.5 I7.6 23.7 II.5 25.I ±Ɵ.6 (2Ɵ.3M25.4) (I8.3M2 I.8) (24.3M25.6)

HL I2.6 I 3.I II.8 7.4, 8.2 7.8 I3.3 I2.2±Ɵ. 2 II. I±Ɵ.7 IƟ.I I2.6 7.7 I3.7±Ɵ.2 (II.9 MI2.3) (IƟ.4MI2.3) (I3.4MI4.Ɵ)

HW 9.4 IƟ.6 9.5 5.2, 6.Ɵ 5.6 IƟ.3 9.3±Ɵ.3 8.2±Ɵ.7 7.3 9.4 5.6 II.5 ±Ɵ.9 (9.ƟM9.7) (7.5M9.2) (IƟ.8MI2.7)

HD 6.8 7.I 7.2 3.6, 4.2 3.9 6.9 6.4±Ɵ.8 5.6±Ɵ.5 4.7 6.I 4.4 8.3±Ɵ.7 (5.6M7.5) (5.ƟM 6.I) (7.8M9.2)

SEyL 5.3 5.7 5.5 3.5, 3.9 3.6 5.9 5.3±Ɵ.2 4.9±Ɵ.3 4.3 5.4 3.5 5.9±Ɵ.I (5.IM5.5) (4.6M5.3) (5.8M 6.I)

EyD 3.6 3.7 3.8 2.6, 2.5 2.9 3.9 3.6±Ɵ.3 3.3±Ɵ.2 2.9 3.6 2.5 4.Ɵ±Ɵ.2 (3.2M3.9) (3.IM3.6) (3.8M4.2)

EyEaL 5.5 5.9 5.I 3.Ɵ, 3.4 3.Ɵ 6.2 4.9±Ɵ.3 4.6±Ɵ.4 3.9 5.6 2.9 6.4±Ɵ.5 (4.5M5.3) (4.IM 5.I) (5.9M7.Ɵ)

SEaL I4.4 I 5.I I2.8 8.Ɵ, 8.8 8.2 I5.2 I3.7±Ɵ. 6 I 2.5±I.Ɵ IƟ. 8 I 4.4 8.2 I6. Ɵ±Ɵ.6 (I3.3MI4.5) (II.5 MI3.8) (I5.3MI6.8)

FLL I8.3 I7. Ɵ I8. Ɵ 9.I, I2. Ɵ II.I I9.5 I8. Ɵ±Ɵ. 9 I 6.8± I.7 I3.9 I8.4 9.2 I9. Ɵ±Ɵ.3 (I7. ƟMI9.2) (I4. ƟMI8.6) (I8.6MI9.3)

HLL 27.I 27.I 25.8 I4, I 7.I I5.3 3Ɵ.3 25.8±Ɵ.9 24.8± I.7 23.2 27.I I5.9 26.9±Ɵ.5 (24.7M27.Ɵ) (22.7M27.Ɵ) (26.4M27.6)

T4L 9.6 9.I 8.7 5.3, 6.Ɵ 5.9 II.5 9.7±Ɵ.3 9.6±Ɵ.7 8.7 IƟ.I 6.3 9.3±Ɵ.3 (9.3MIƟ.I) (IƟ.3M8.8) (9.IM9.7)

Regenerateđ; b Tip of tail lost; c Broken; đ Ιncluđing incomplete tails that were regenerateđ or partially lost; e Enđ at regenerateđ portion; ―, not taken đue to poor conđition.

Nostril in anterior region of nasal; nasal slightly smaller than first supralabial, overlapping anterior loreal, supranasal, and first supralabial; postnasal absent on each side; anterior loreal twice as high as wide, overlapped by supranasal and first supralabial, overlapping posterior loreal and second supralabial; posterior loreal wider than high, overlapping first supraciliary, preocular, first presubocular, and third supralabial, overlapped by second supralabial; eight supraciliaries on each side, anterior ones overlapping posterior ones, first one largest, second and third one as wide as high, fourth to seventh ones wider than high, eighth one elongated; one small preocular on each side, contacting first presubocular, overlapping first supraciliary; two presuboculars on each side, anterior ones overlapping posterior ones, first one shorter than first supraciliary, overlapping, third and fourth supralabials, second one smaller than first one, overlapped by fourth supralabial; two small postoculars on each side, upper one overlapping eighth supraciliary, upper pretemporal and lower postocular, lower one overlapping two pretemporals and third postsubocular on left side (fourth postsubocular on right side); three postsuboculars on left side (four on right side), first one overlapping second one and sixth supralabial, second one overlapping sixth supralabial and primary temporal, third one overlapping second one, primary temporal, and lower pretemporal on left side (overlapped by second one, overlapping primary temporal on right side, fourth one overlapping third one and lower pretemporal, and primary temporal only on right side); two pretemporals on each side, upper one overlapping lower one, lower one overlapping primary and upper secondary temporals; single primary temporal on each side, obliquely elongated, overlapped by sixth supralabial, overlapping two secondary temporals and seventh supralabial; two seconadary temporals on each side, upper one fan-shaped with slightly emarginated posterior margin and much larger than lower one, overlapping nuchal and two tertiary temporals, lower one elongated, overlapped by seventh supralabial, overlapping upper one, lower tertiary temporal, and upper postlabial; two tertiary temporals on each side, much higher than wide, upper one overlapped by lower one, and nuchal; seven supralabials on each side, anterior ones overlapping posterior ones, first to fourth ones similar in size and smaller than succeeding three, fifth and sixth ones intermediate in size, below eye, seventh one largest; two postlabials on each side, followed by a few small scales separating from ear opening, upper one overlapped by lower tertiary temporal and overlapping lower one on left side (overlapping lower tertiary temporal and lower one on right side), each one overlapped by seventh supralabial; three small auricular lobules in anterior margin of ear opening on left side (two on right side); lower eyelid with vertically elongated scales on each side, separated from presuboculars and postsuboculars by two or three rows of granules.

Mental wider than long, rounded anteriorly, overlapping first infralabial and postmental; single postmental with pentagonal shape, slightly longer than mental, overlapped by first and second infralabials, overlapping first chin shield; five infralabials on left side (six on right), anterior ones overlapping posterior ones, first ones as wide as high, second to fifth ones (second to sixth ones on right side) wider than high, fifth one (sixth one on right side) widest; three pairs of chin shields, obliquely elongated, anterior ones overlapping posterior ones, first one overlapped by second and third infralabials, left one overlapped by right one anteriorly, second one overlapped by third and fourth infralabials, left one separated from right one by one gular scale, third one overlapped by fourth infralabial, left one separated from right one by four gular scales; pair of postgenials, more than two times as long as wide, overlapped by fourth and fifth infralabials on left side (fourth to sixth on right side); scales medially overlapped by postgenials longer than wide.

Body scales smooth, dorsal and ventral ones nearly equal in size, slightly larger than lateral ones; 36 scale rows around neck just anterior to forelimb, 28 rows around middle of body; 55 pairs of paravertebral scales; subcaudals wider than other scale rows around tail, 83 scales; 13 scale rows around tail at tenth subcaudal position; pair of enlarged preanals, left one overlapping right one, both overlapped by smaller outer scales; pair of keeled lateral postanal scales in postanal region.

Limbs well developed, scales smooth, about as large as or smaller than lateral ones on body; hands with five distinct fingers, third one longest, subdigital lamellae 7–10–12–13–9 / 7–10–12–14–9 on left/right fingers, granular scales on palm with larger ones centered; patch of enlarged irregular scales on posterior femur; feet with five distinct toes, fourth one largest, subdigital lamellae 6–11–17–22–12 / 7–11–17–20–13 on left/right toes, granular scale on sole with larger ones near ankle.

Color. In preservative, dorsum of hatchling (based on OPM-H-560) light brown with five longitudinal grayish lines except for grayish distal portion of tail. MDL beginning on snout, bifurcating on nuchals, and extending on paravertebrals to proximal portion of tail. DLL beginning from first supraocular, running on third scale row at midbody, and ending around the same position as MDL. LL beginning just behind ear opening, running on sixth scale row at midbody, and fading before end of MDL and DLL. Venter cream except for middle body (partially brownish or grayish cream) and distal portion of tail (slightly brownish cream). Regenerated part of tip of tail cream. For subadults (based on KUZ R18077, 32163, 32165, 32167–9) and adults (based on KUZ R32162, 32164, 32166, 32170, 35252, 39041–3), dorsal surface of head brown or dark brown. Dorsal surface of body and limbs dark brown or grayish brown. Dorsolateral region of three adults slightly reddish brown with a few black scales near forelimb. Dorsal surface of tail like dorsal surface of body, but regenerate portion light brown or gray. Longitudinal line fading but partially retaining (six subadults and three adults), or entirely lacking (five adults). In midbody region, MDL retaining in half of subadults (n = 3), DLL in most subadults (n = 5) and a few adults (n = 2), and LL in one subadult. Ventral surface of head cream or white. Ventral surface of body entirely blackish gray or grayish white, or cream medially and blackish cream laterally. Ventral surface of limb cream, dark cream, or white. Ventral surface of tail entirely white, entirely cream, white with brownish regenerated portion, cream with grayish regenerated portion, white with brownish proximal portion, or cream with darker proximal portion. See Ota (2004) for coloration of hatchling in life.

Variation. Variations in the morphometric and meristic characters are presented in Tables 6 and 7. The number of PN, PrO, SuO, PoO, PrT, T1, T2, SL, and PM is not listed in Table 7 as they are in the same state as in the holotype. Specimens in the type series other than the holotype consistently possess a pair of Nu. In addition, the CLPS is always keeled, and an EISPF is always present. The frontal of KUZ R1 8077 is divided into anterior and posterior parts. The third CS and IL of KUZ R39041 are separated by the contact between the second CS and the postgenial scales on the left side.

Type Holotype Paratypes

(KUZ R32170)

a Not counted except for on the right side of one specimen due to poor condition. b Taken from a single specimen due to the others having imperfect tails.

Distribution. This species occurs on four islands (Uotsurijima, Kitakojima, Minanikojima, and Kubajima Islands) in the Senkaku Group, Southern Ryukyus (Ishigaki City, Okinawa Prefecture), Japan.

Natural history. Plestiodon takarai was frequently observed around rocks in various habitats, including coastal areas, shrublands, mountain forests, and grasslands ( Takara 1954; Ikehara & Shimojana 1971; Ota et al. 1993). Ikehara & Shimojana (1971) reported that this lizard was also found among Crepidiastrum lanceolatum near a crater on Kubajima Island. An adult female that was collected on Uotsurijima Island in May 1979 (KUZ R18922) contained three ova (largest = 2.9 mm diameter). The testis size of adult males collected on Kubajima Island in May 1991 (KUZ R39041–43) ranged from 3.2 to 3.6 mm (mean = 3.4 mm) in maximum diameter. Ota (2004) observed the brooding behavior of females on Kitakojima Island, whereby each female surrounded her clutch with the whole body and tail in nests that were located beneath coral rocks on the ground. He also noted the clutch size (6–7), egg size (length = 15.0– 17.9 mm; width = 10.9–12.3 mm; mass = 0.94–1.43 g), hatchling size (SVL = 27.9–30.8 mm; TaL = 42.3–47.3 mm; mass = 0.4 6– 0.62 g), and hatchling date (mid to late June) on that island. The stomach contents of a hatchling female from Uotsurijima Island (KUZ R18923) included two beach fleas, a wharf roach, a lepidopteran larva, and a leafhopper nymph, while on Minamikojima Island, this species was observed taking a piece of half-digested fish that had been regurgitated by a booby for its chick ( Hikida 1979; H. Ota, private communication from the late Dr. Sadao Ikehara with motion films). A similar interaction between these lizards and nesting seabirds was also observed on Uotsurijima Island ( Ota 2014; H. Ota, private communication from the late Dr. Sadao Ikehara with motion films).

Etymology. The species name is dedicated to the late Dr. Tetsuo Takara, Emeritus Professor at the University of the Ryukyus. As the pioneer of modern biological and geological studies on the Senkaku Group after WWII, Dr. Takara led the survey team and conducted fieldwork on this island group five times between 1950 and 1968 ( Senkaku Survey Team 2007). Suggested common names: Senkaku-Tokage (Japanese); Senkaku Skink (English).

Figures

FIGURE 3. Dorsal (A), lateral (B), and ventral (C) views of head scutellation in the holotype of Plestiodon takarai sp. nov. (KUZ R 32170). Abbreviations for scale characters: CS, chin shield; F, frontal; FN, frontonasal; FP, frontoparietal; IL, infralabial; IP, interparietal; L, loreal; M, mental; N, nasal; Nu, nuchal; P, parietal; PF, prefrontal; PG, postgenial; PL, postlabial; PM, postmental; PoO, postocular; PoSO, postsubocular; PrO, preocular; PrSO, presubocular; PrT, pretemporal; R, rostral; SL, supralabial; SN, supranasal; SuC, supraciliary; SuO, supraocular; T 1, primary temporal; T 2, secondary temporal; T 3, tertiary temporal. Scale bar = 5 mm.

FIGURE 4. Bar graph showing the numbers (left-right) of supralabials in contact with the posterior loreal (A) and arrangement of a pair of prefrontals (B) in Plestiodon takarai sp. nov. from the Senkaku Group (Uoturijima, Kikakojima, Minamikojima, and Kubajima Islands) and P. elegans. Data for P. elegans were obtained from Hikida (1989) for A and Van Denburgh (1912 b) for B.