Plestiodon latiscutatus Hallowell, 1861

Okamoto, Taku & Hikida, Tsutomu, 2012, A new cryptic species allied to Plestiodon japonicus (Peters, 1864) (Squamata: Scincidae) from eastern Japan, and diagnoses of the new species and two parapatric congeners based on morphology and DNA barcode, Zootaxa 3436 (1), pp. 1-23 : 15-16

Plestiodon latiscutatus Hallowell, 1861

(Japanese name: Okada-Tokage)

( Table 1)

Scincus quinquelineatus: Temminck & Schlegel, 1838, p. 99 , p. 193 (in part)

Plestiodon quinquelineatus: Duméril & Bibron, 1839, p. 707 (in part)

Plestiodon quinquelineatum: Gray, 1845, p. 91 (in part); Bleeker, 1858, p. 205 (in part)

Plestiodon latiscutatus: Hallowell, 1861, p. 496 ; Okamoto et al., 2006, p. 419; Kuriyama et al., 2006, p. 793; Honda et al., 2008, p. 351; Okamoto & Hikida, 2009; Brandley et al., 2011 p. 7; Brandley et al., 2012 p. 166

Eumeces (Plestiodon) japonicus: Böettger, 1878, p. 4 (in part)

Eumeces japonicus: Bocourt, 1879, p. 423 (in part)

Eumeces marginatus: Boulenger, 1887, p. 371 (in part); Okada, 1891, p. 70 (in part); Böettger, 1893, p. 111 (in part); Fritze, 1894, p. 860 (in part)

Eumeces quinquelineatus: Fritze, 1891, p. 239 (in part)

Eumeces latiscutatus latiscutatus: Stejneger, 1907, p. 195 (in part); van Denburgh, 1912, p. 213 (in part); Okada, 1939, p. 162 (in part)

Eumeces latiscutatus okadae: Stejneger, 1907, p. 200 ; van Denburgh, 1912, p. 214; Okada, 1939, p. 166

Eumeces latiscutatus: Barbour, 1909, p. 63 (in part); Hatta, 1914, p. 31 (in part); Taylor, 1936, p. 276 (in part); Nakamura & Uéno, 1963, p. 106 (in part); Hikida, 1979a, p. 38 (in part); Hikida, 1993, p. 2 (in part); Kato et al., 1994, p. 419 (in part); Hikida, 1996, p. 80 (in part); Hikida & Motokawa, 1999, p. 235 (in part); Motokawa & Hikida, 2003, p. 97 (in part); Goris & Maeda, 2004, p. 165

Eumeces okadae: Taylor, 1936, p. 272 ; Nakamura & Uéno, 1963, p. 108; Hikida, 1979b, p. 40; Hikida, 1993, p. 3; Kato et al., 1994, p. 491; Hikida, 1996, p. 80; Hikida & Motokawa, 1999, p. 235; Motokawa & Hikida, 2003, p. 97

Diagnosis. A moderate-sized Plestiodon (ca. 60–90 mm SVL for adults) similar to P. finitimus . This species differs from P. barbouri in usually having 24–30 MSRs. The Izu Peninsular population of this species differs from P. finitimus and P. japonicus in usually having a large postnasal contacting with the posterior loreal ( Fig. 2B ), or sometimes lacking a postnasal ( Fig. 2C ), and having a slightly smaller number of MSRs (24 and 26 in similar frequencies, range, 22–26). The Izu Insular populations, except that of Izuoshima Island, differ from P. finitimus and P. japonicus in lacking the bifurcating pattern of the dorsal yellowish stripe on the juvenile head. The insular populations differ from P. finitimus and P. japonicus in having a larger number of MSRs (usually 28 or 30), with geographic variation.

DNA barcode. The nucleotide sequence of the 658 bp fragment of the mitochondrial COI gene (the standard barcode region) from five specimens from two localities (including the type locality) was determined and deposited in the GenBank database (Accession No. JN089942 –46) .

Variation. The Izu Peninsular and Izuoshima Island populations have similar color patterns during ontogeny and sexual dimorphism, including the breeding season coloration, to P. finitimus , although adults of this species have a slightly darker and greenish dorsal color and reddish brown dorsolateral color compared with P. finitimus and P. japonicus . Juveniles of the other populations have no bifurcating pattern on the head and a faded blue tail, and tend to change their color pattern at an earlier stage of ontogeny ( Taylor 1936; Hikida 1979b; Kuriyama et al. 2006; Kuriyama et al. 2009a).

The number of MSRs is usually 24 or 26 (range, 22–26) in the Izu Peninsular population, compared with 28 or 30 (range, 26–32) in the insular populations, with variation among the islands ( Hikida 1979b; Hikida 1993).

Distribution. The Izu Peninsula, Hatsushima Island, and most of the Izu Islands. Around the Izu Peninsula, the eastern side of the lower Fuji River, the southern side of Mt. Fuji, and the southwestern side of the Sakawa River ( Okamoto et al. 2006). The southernmost distribution is Aogashima Island ( Hikida 1979b; Hikida 1993).

Note. The populations on three islands (Miyakejima, Hachijojima, and Aogashima Islands) have been threatened by predation pressure from the artificially introduced Japanese weasel Mustela itatsi Temminck ( Hasegawa 1999) and are listed in the national red data book of Japan ( Hasegawa & Ota 2000).

Figures

FIGURE 2. Observed major character states in arrangement of postnasal, supralabial, anterior loreal, and posterior loreal (PN) scales. p: postnasal; sl: supralabial; a: anterior loreal; po: posterior loreal.