A new species of Sun Skink (Reptilia: Scincidae: Eutropis ...

PRIMARY RESEARCH PAPER | Philippine Journal of Systematic Biology

DOI 10.26757/pjsb2020b14012 urn:lsid:zoobank.org:pub:0938ACCF-60DF- 45D1-B207-0827356E97A7

Volume 14 Issue 2 - 2020 | 1 © Association of Systematic Biologists of the Philippines

A new species of Sun Skink (Reptilia: Scincidae: Eutropis)

from the Zamboanga Peninsula, southwestern Mindanao

Island, Philippines

Abstract

We describe a new species of lizard in the genus Eutropis Fitzinger 1843 from the southwestern tip of the Zamboanga

Peninsula on the western part of Mindanao Island, Philippines. The new species is related to Eutropis rugifera, which is a

secretive, forest-adapted skink that ranges widely outside the Philippines from the western extent of its distribution on

Nicobar Island (the type locality) through southern Peninsular Malaysia, Sumatra and the Mentawai islands, Borneo, Java,

and as far east as Bali Island. The discovery of a new, morphologically distinct, and genetically highly divergent Sun

Skink lineage in the low elevation forests of Zamboanga Peninsula creates a puzzling disjunct geographic distribution (E.

rugifera has not been reported from the Sulu Archipelago). The new species is estimated to have diverged ~10–16 mya

from E. rugifera, from which it appears to have an extralimital and isolated distribution. Considering the dynamic

geological history and ancient continental origin of the Zamboanga Peninsula, colonization by the new species may have

been facilitated by pre-Pleistocene overseas long-distance dispersal, saltatory range expansion and subsequent

contraction/extinction in the Sulu Archipelago, and/or possibly paleotransport on the ancient crustal fragment of

Zamboanga. The new species is known only from Zamboanga City’s primary surface water supply catchment at the

lowest elevations inside the boundaries of Pasonanca Natural Park, despite the fact that there have been historical surveys

of herpetological diversity at multiple sites to the northeast (Zamboanga, western Mindanao) and to the southwest (Sulu

Archipelago). The new species, thus, may be limited to just the tip of the Zamboanga Peninsula, possibly rendering

Pasonanca’s low elevation forests its most critical habitat resource for long term persistence and survival of the species.

Keywords: IUCN Red List, Palawan microcontinent block, Pasonanca Natural Park, Sulu Archipelago, Surface

catchment watershed biodiversity

1* School of Life Sciences, University of Hawai‘i, Honolulu, HI 96822,

USA;

2 Biodiversity Informatics and Research Center, Father Saturnino Urios

University, San Francisco Street, 8600 Butuan City, Philippines 3 Biodiversity Institute and Department of Ecology and Evolutionary

Biology, University of Kansas, Lawrence, KS 66045, USA

*Corresponding email: [email protected]

Date Submitted: 6 July 2020

Date Accepted: 1 February 2021

Introduction

The genus Eutropis is a moderate size group of scincid

lizards that are widespread and abundantly distributed across

Asia (Mausfeld and Schmidt 2003; Grismer 2011; Uetz et al.

2020). Also known as Sun Skinks, these lizards historically

have constituted a major taxonomic conundrum. As in many

other groups of tropical vertebrates, preliminary genetic studies

suggest that cryptic diversity is likely present within populations

of many species (Ota et al. 2001; Mausfeld and Schmitz 2003;

Barley et al. 2013), and in recent years, new species have been

described from across Asia (Mausfeld and Böhme 2002; Das et

al. 2008; Batuwita 2016). Much of this overlooked diversity can

be ascribed to the historical taxonomic focus on identifying

lineages using external morphological characters (which

frequently vary little among populations), as well as the group’s

broad distribution across southern Asia, including many

countries and landmasses that are politically divided and

logistically difficult for field biologists to access (Barley et al.

2015a; Amarasinghe et al. 2017).

Although genetic studies are providing novel insights into

sun skink diversity, this new source of information is also

challenging to interpret from a taxonomic perspective.

Taxonomic resolution in many sun skink lineages is hampered

by data limitations. For example, many widespread species lack

Anthony J. Barley1*, Marites B. Sanguila2 and Rafe M. Brown3

mailto:[email protected]

Volume 14 Issue 2 - 2020 | 2 Philippine Journal of Systematic Biology Online ISSN: 2508-0342

Barley et al.: A new species of Eutropis from the southern Philippines

robust population-level sampling (but see Barley et al. 2015a),

and the genetic information that is available is often limited to

one, or a small number of loci, which is widely recognized as

being insufficient for reliably identifying species boundaries

(Irwin 2002; Funk and Omland 2003; Hinojosa et al. 2019).

Additionally, many species occur in naturally fragmented

habitats, such as archipelagos, where population differentiation

is expected to be high, although these genetic differences will

often not be representative of a speciation event. Thus, reliance

on morphological information will often lead to taxonomic

conclusions that underestimate species diversity, whereas

reliance on genetic information may lead researchers to

overestimate species-level diversity in these types of systems

(e.g., Barley et al. 2013). Combining both sources of data with

information about ecology and geographic distributions can

help mitigate these sources of taxonomic bias in sun skinks, and

potentially aid in the recognition of the total diversity of

evolutionary lineages (species), whether or not they can be

readily identified on the basis of external morphology (Barley et

al. 2020). Of particular interest is the Philippine Archipelago,

widely recognized as a global biodiversity hotspot where

species diversity is thought to be substantially underestimated in

nearly all major terrestrial vertebrate groups (Brown and

Diesmos 2009; Brown et al. 2013). Sun skink species diversity,

first comprehensively reviewed in the Philippines 40 years ago

by W.C. Brown and A.C. Alcala (Brown and Alcala 1980; see

also Taylor 1922) was nearly tripled in a single lineage of

Philippine Eutropis by a recent taxonomic revision (Barley et

al. 2020) and biogeographic studies suggest that the Philippines

was likely invaded from the Sunda Shelf by Eutropis 2–4

independent times (Barley et al. 2015a).

Biogeographic patterns in island systems are shaped by

their geologic history, with older and more isolated islands

typically having a higher proportion of endemic species (Evans

et al. 2003; Siler et al. 2012; Brown et al. 2016). In Southeast

Asia, historical sea-level fluctuations have played a major role

determining terrestrial diversity patterns, where dry land

connections that appeared among islands when sea levels

dropped to 120 m below present during the last glacial

maximum (Miller et al. 2005) connected populations and

facilitated dispersal. For example, this led some species on

Palawan Island of the southwestern Philippines to be more

closely allied to those on Sundaland than the remainder of the

Philippines which remained isolated (Inger 1954; Heaney

1985). Other groups appear to have arrived on Palawan via

dispersal from the north (Esselstyn et al. 2010) or possibly as a

result of paleotransport on the Palawan Microcontinent Block

(Yumul et al. 2009a; Siler et al. 2012; Brown et al. 2016) which

rifted from continental Asia 40–35 mya and arrived at its

current location 10–6 mya (Yumul et al. 2009a; Hall 1998,

2002; Blackburn et al. 2010). Similar patterns have been

documented in the southwestern Philippines, in particular the

Sulu Archipelago and Mindanao Island, which have been

interpreted as receiving substantial proportions of their reptile

faunas by overland colonization from the Sunda Shelf (Taylor

1928; Inger 1954; Leviton 1964; Brown and Alcala 1970).

Finally, in addition to dispersal corridors via land bridges (Inger

1954; Diamond and Gilpin 1983), the ‘species-pump’ action of

oscillating sea levels may have contributed to regional

population differentiation within the oceanic portions of the

Philippines (Brown and Diesmos 2009), although this

mechanism may only explain a portion of in situ species

diversification in the endemic terrestrial vertebrate clades

(Esselstyn and Brown 2009; Siler et al. 2010; Setiadi et al. 2011;

Blackburn et al. 2013; Oaks et al. 2013, 2019; review: Brown et

al. 2013).

The “five-keeled” or “rough-scaled” Sun Skink [Eutropis

rugifera (Stoliczka 1870)] occurs widely across Southeast Asia,

its distribution encompassing Peninsular Malaysia south of the

Isthmus of Kra, virtually all large islands on the Sunda Shelf,

and the Nicobar Islands (the species’ type locality). In 2015, a

related population was first reported from the extreme

southwestern Philippines (Barley et al. 2015a). Similar to other

members of the genus, E. rugifera is a generalist insectivore

Figure 1. Map showing sampling localities within the geographic

distribution of Eutropis alcalai sp. nov. from the Zamboanga Peninsula

(green dots), and the much broader range of its closest relative, E.

rugifera (type locality: Nicobar Island; red dots). Inset: known records

for E. alcalai sp. nov. within Pasonanca Natural Park (southern point

0.5 km above intake area, Barangay Pasonanca [type locality]; northern

point Cabo Negro Outpost area, Barangay Tolosa).



found in interior, lowland, primary and mature secondary

tropical forests (Karin et al. 2017; Amarasinghe et al. 2017).

Nicobar Island and newly discovered Philippine populations

are, thus, the biogeographically disjunct extreme western and

eastern limits of the group’s documented range (Fig. 1).

In a range-wide treatment of the Eutropis rugifera group,

Karin et al. (2017) interpreted ~6 mya (divergence time

estimated through a relaxed-clock phylogenetic analysis

calibrated with a typical reptile mtDNA substitution rate),

divergences among populations of E. rugifera from Sundaland

landmasses (Sumatra, Malay Peninsula, Mentawai islands and

Borneo) as evidence that environmental barriers likely persisted

through the Pleistocene despite the existence of land-bridges.

These xeric environmental barriers may have maintained and

reinforced population structure (by inhibiting dispersal and gene

flow) in forest obligate species, which formerly were thought to

have been unified (via corridors for dispersal) upon exposure of

the Sunda Shelf during Pleistocene sea-level reductions (Inger

1954; Voris 2000; Bird et al. 2005; Cannon et al. 2009).

Previous work also clearly demonstrated that the significant

evolutionary divergence between the Zamboanga population

and the rest of the species complex likely has resulted in a

speciation event (Barley et al. 2015a; Karin et al. 2017). In this

paper, we formally recognize this lineage as a highly distinctive

new Sun Skink from the low elevation rainforests of Pasonanca

Natural Park on the outskirts of Zamboanga City.

Materials and Methods

Genetic Data and Phylogeny Estimation

We assembled several datasets using genetic data available

from GenBank to evaluate the evolutionary relationships of

populations assigned to E. rugifera with respect to other

Southeast Asian Eutropis. To summarize what is currently

known about the broadscale phylogenetic relationships of

Eutropis, we first combined one mitochondrial and nine nuclear

genes (see Barley et al. 2015a) with the available 12s and 16s

data. For this analysis, we selected a single individual per

species, though we also created several chimeric sequences in

order to maximize phylogenetic resolution if we were confident

that the sequences were drawn from the same lineages (based

on preliminary analyses of the individual gene trees and current

taxonomic knowledge; Table 1). To evaluate the genetic

relationships among E. rugifera populations, we combined data

for the ND2 mitochondrial gene and the MC1R, BRCA1, and

RAG1 nuclear genes from Barley et al. (2015a) and Karin et al.

(2017). We reconstructed an additional E. rugifera dataset for

the ribosomal RNA 16S mitochondrial gene (Amarasinghe et al.

2017) because a single individual was sampled from the type

locality. However, this dataset was not combinable with the

former E. rugifera dataset because it lacked overlapping

taxonomic sampling.

For each dataset we performed a concatenated Bayesian

phylogenetic analysis of the data using MrBayes 3.2.6 (Ronquist

et al. 2012), selecting models of molecular evolution (from

among the 20 commonly implemented in MrBayes) and the

optimal partitioning strategy using Bayesian information

criterion in PartitionFinder v2.1.1 (Lanfear et al. 2014). We ran

MrBayes analyses (consisting of two runs with eight chains

each) for 50 million generations, sampling every 5,000

generations, and assessed convergence using the average

standard deviation of split frequencies and potential scale

reduction factor diagnostics in MrBayes, and by ensuring that all

parameters had effective sample sizes >1,000 using Tracer v1.7

(Rambaut et al. 2018). Topological convergence was assessed

using the R package RWTY (Warren et al. 2017). We rooted the

phylogenetic tree from the genus-wide analysis according to

Barley et al. (2015a), whereas the two analyses focused on the

E. rugifera complex were rooted with E. multifasciata (Kuhl

1820) (not shown).

Morphological Data

We compared specimens from our Philippine collections to

Eutropis rugifera specimens from landmasses of the Sunda

Shelf (Sumatra, Borneo), and we relied heavily on the recent

study of Amarasinghe et al. (2017) who reported on specimens

from the type locality (Camorta, Nicobar Island, northwest of

Sumatra; Fig. 1), redescribed the holotype of E. rugifera in

detail, reviewed the taxonomic history of the species and its

synonyms (Euprepes percarinatus Peters 1871 & E. p. var.

borneensis Peters 1871 [Java], Mabuia rubricollis Bartlet 1895

[Borneo], Mabuia quinquecarinata De Rooij 1915 [Sumatra]),

and compared morphological variation among specimens from

the disjunct populations located on various Sundaic landmasses

throughout the range of this widely distributed, yet poorly

phenotypically characterized species (Chan-ard et al. 1999;

Malkmus et al. 2002; Das 2004; Chan et al. 2010; Grismer 2011;

Venugopal 2010; Karin et al. 2017). We assembled our dataset

from newly collected specimens, historical museum specimens

(see Specimens Examined section) and the literature mentioned

above. Fluid-preserved specimens we examined are housed at

the University of Kansas Biodiversity Institute (KU), The Field

Museum (FMNH), the Smithsonian Institution (USNM), the

Museum of Vertebrate Zoology (MVZ) at the University of

California, Berkeley, the Museum Zoologicum Bogoriense

(MZB) and the National Museum of the Philippines (PNM);

Institutional museum codes follow Sabaj (2019).



We used Mitutoyo digital calipers (RMB measured

specimens, in mm, ± 0.1 mm) and a Leica Wild MZ12

microscope with installed micrometer, to measure mensural

characters (from the left side of the body) and take meristic data

(scale counts), following definitions of Amarasinghe et al.

(2017) with a few modifications (see below) to clarify

ambiguities; these modifications with respect to head length,

paravertebrals, and ventrals allow for direct comparisons with

Amarasinghe et al. (2017), and also comparisons to other,

earlier works (Brown and Alcala 1980; Greer and Nussbaum

2000; Das 2004; Grismer 2011). Measurements included snout–

vent length (SVL), and the lengths of the forearm, femur, tibia,

foot, head, snout, and 4th toe. Because of our difficulty reliably

identifying the posterior edge of the mandible (Amarasinghe et

al. [2017] used “posterior edge of the mandible to the tip of the

snout” as head length), we also measured and report what we

feel is a more repeatable head length definition: from the

anterior edge of the auricular opening to the tip of the snout. We

also measured head width, horizontal eye (orbit) diameter,

auricular opening diameter, axilla-groin distance, eye–auricular

opening distance, and eye–nostril distance. We counted

supralabial and infralabial scales from the upper and lower jaw

symphysis to rostral and mental scales, respectively. To

facilitate comparisons with other published work, we reported

ventrals and dorsals using the various methods used by different

investigators (Brown and Alcala 1980; Das 2004; Grismer

2011; Amarasinghe et al. 2017); thus, we counted and reported

ventrals from the postmental to the precloacals and also

between the midpoints of limb insertions. We counted

paravertebral scales between nuchals (included) to the region

posterior to the thigh immediately dorsal to the opening of the

cloaca (counted in a straight line immediately left of the

middorsal line) and also along the spine (the middorsal-most

scale row) between the dorsal midpoints of limb insertion. We

counted subdigital lamellae underneath the 4th toe from the first

proximally differentiated (enlarged) scale to the distal-most

lamella before the claw. Sex was determined by everted

hemipenes or ventral tail dissection (males) or presence of

oviducts and embryos (females). For standardization of color

descriptions of the new species, we incorporated the numbered

color scheme from Köhler’s (2012) standardized color guide.

Results

We update two taxonomic identification errors to avoid

continued confusion from previous phylogenetic studies.

Batuwita (2016) suggested that the ‘Eutropis madaraszi’ of

Mausfeld et al. (2003) actually corresponds to E. austini

Batuwita 2016, however, we tentatively assign the sequence to

the taxon E. greeri based on examination of photos of the

specimen (Kanishka Ukuwela, personal communication).

Additionally, our data suggest the ‘E. indeprensa’ of Karin et al.

(2016) is likely to be a specimen of E. cumingi (Brown & Alcala

1980), as the individual they sequenced is from Lubang (the

species to which that population is assigned; Barley et al. 2020).

We follow the unified, general concept of species as separately

evolving metapopulations when interpreting the taxonomic

implications of the results (De Queiroz 1998, 2007).

Genetic Data and Phylogeny Estimation

The twelve-gene species-level phylogenetic analysis of

Eutropis (Fig. 2a) suggests that the E. rugifera lineage is

evolutionarily divergent from other Southeast Asian Eutropis

and indicates weak support for a sister relationship with E.

tytleri (Theobald 1868), a poorly known endemic from the

Andaman Islands (Chandramouli and Amarasinghe 2020). The

four-gene phylogeographic analysis shows that the Philippine

populations are genetically divergent from Malaysian and

Indonesian populations of E. rugifera at both mitochondrial and

nuclear loci (Fig. 2b). Phylogenetic analyses of the 16s data

show that the Malaysian and Indonesian E. rugifera populations

are minimally divergent from the type locality populations on

Nicobar Island (Fig. 2c). Although these data also suggest a

close relationship between the Nicobar and the Sumatran E.

rugifera populations (a result also seen in other co-distributed

species), the remaining phylogeographic relationships within

this lineage are poorly resolved. We do not use degrees of

genetic distance among populations to diagnose the new species

described below. However, we emphasize that the genetic

divergence (~17–18% uncorrected p-distance for ND2 mtDNA)

and ancient date estimated for the divergence of the Zamboanga

lineage from its common ancestor with E. rugifera (10–16 mya)

provide overwhelming support for the two lineages being

recognized as distinct species (Barley et al. 2015; Karin et al.

2017).

Morphological Data

Our examination of our small series of specimens from

Pasonanca Natural Park (on the outskirts of Zamboanga City, at

the SW tip of Zamboanga Peninsula, Mindanao Island)

identified unambiguous, discretely variable (i.e., non-

overlapping ranges) character values, in multiple meristic and

color pattern character states between the Zamboanga lineage

and all other populations of Eutropis rugifera from throughout

the Sundaic landmasses (Borneo, Bali, Java, Sumatra, Mentawai

Islands, Bawean Island, the Malay Peninsula, and Nicobar

Island; Table 2). We use only fixed character state differences to

diagnose the new species, but several other narrowly



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5191

–

–

–

ma

cula

ria

KJ5

747

52

JQ7

679

73

JQ7

679

57

KJ5

744

46

–

KJ5

746

75

KJ5

747

87

KJ5

744

68

KJ5

745

16

KJ5

748

35

KJ5

745

87

KJ5

749

25

mu

ltic

ari

na

ta

KF

23

5293

–

–

KF

23

4822

KF

23

5115

KF

23

4970

KF

23

5044

KF

23

4895

KF

23

5189

KJ5

748

28

KJ5

745

80

KJ5

749

18

mu

ltif

asc

iata

K

J57

47

18

DQ

239

219

KX

23

1451

KJ5

744

33

KJ5

749

90

KJ5

746

61

KJ5

747

74

KJ5

744

76

KJ5

745

24

KJ5

748

60

KJ5

746

12

KJ5

749

50

naga

rjun

ensi

s K

J57

47

54

JQ7

679

72

JQ7

679

52

–

–

KJ5

746

78

–

KJ5

744

93

KJ5

745

40

KJ5

748

61

KJ5

746

13

KJ5

749

51

pala

uen

sis

KF

23

5273

AY

15

9067

AY

15

9096

KF

23

4808

KF

23

5102

KF

23

4956

KF

23

5031

KF

23

4881

KF

23

5175

KJ5

748

19

KJ5

745

71

KJ5

749

09

quad

rica

rinata

K

J57

47

22

AY

15

9060

AY

15

9089

KJ5

744

35

–

KJ5

746

64

KJ5

747

77

KJ5

744

79

KJ5

745

36

KJ5

748

63

KJ5

746

15

KJ5

749

53

rudis

K

J57

47

24

DQ

239

216

DQ

238

894

KJ5

744

37

KJ5

749

94

KJ5

746

66

KJ5

747

79

KJ5

744

81

KJ5

745

28

KJ5

748

65

KJ5

746

17

KJ5

749

55

rugif

era

KJ5

747

27

AY

15

9050

KX

36

4957

KJ5

744

40

KJ5

749

97

KJ5

746

69

KJ5

747

82

KJ5

744

84

KJ5

745

31

KJ5

748

68

KJ5

746

20

KJ5

749

58

sahuli

ngha

ng

-g

ana

n

KF

23

5268

–

–

KF

23

4804

KF

23

5098

KF

23

4952

KF

23

5027

KF

23

4877

KF

23

5171

KJ5

748

15

KJ5

745

67

KJ5

749

05

siba

lom

K

F2

35

290

–

–

KF

23

4820

KF

23

5113

KF

23

4968

KF

23

5042

KF

23

4893

KF

23

5187

KJ5

748

26

KJ5

745

78

KJ5

749

16

triv

itta

ta

KJ5

747

32

JQ7

679

71

JQ7

679

51

–

–

KJ5

746

80

–

–

KJ5

745

42

–

–

KJ5

749

62

tytl

eri

–

AY

15

9045

AY

15

9074

–

–

–

–

–

–

–

–

–

Tab

le 1

. S

um

mar

y o

f G

enb

ank d

ata

use

d i

n g

enu

s-w

ide

ph

ylo

gen

etic

an

alysi

s o

f E

utr

op

is (

Fig

2a)

.



overlapping tendencies in character state distributions are

emphasized in the holotype description discussed below. The

new species is also clearly differentiated, both morphologically

and biogeographically, from the populations from which the

currently recognized E. rugifera junior synonyms are derived

(which closely match the diagnostic characters of E. rugifera;

Table 2; see Amarasinghe et al. 2017).

Taxonomic Account

Eutropis alcalai sp. nov.

Eutropis rugifera Barley et al. 2015:296.

LSID: registration: urn:lsid:zoobank.org:pub:0938ACCF-60DF-

45D1-B207-0827356E97A7

Nomenclatural act: urn:lsid:zoobank.org:act:31AE197D-516D-

49C5-9387-1FD8FB4C8197

Holotype.—PNM 9878 (formerly KU 315013; Field No. RMB

9241), adult male, collected 15 July, 2008, by RMB, J. B.

Fernandez, C.D. Siler, L.J. Welton and J.W. Phenix, in low

elevation climax rainforest (semi-open canopy, thin layer of dry

leaf litter, 160 m above sea level) 10 m from the bank of the

Tumaga River, 0.5–0.75 km upstream from Intake Area,

Pasonanca Natural Park, Barangay Pasonanca, Zamboanga City,

SW tip of Zamboanga Peninsula, western Mindanao Island,

Philippines (6.9922333°N, 122.0604333°E).

Paratypes.—KU 321834 (RMB 11651), adult male, collected 10

August, 2009, RMB and C. Infante, in mid-elevation secondary,

regenerating rainforest (semi-open canopy, thin layer of dry leaf

litter, 550 m above sea level) Cabo Negro Outpost, Sitio Santa

Clara, Pasonanca Natural Park, Barangay Tolosa, Zamboanga

City (7.0941°N, 122.0876°E) ; KU 321833 (RMB 11580),

juvenile of undetermined sex, 12 August, 2009, RMB and C.

Infante.

Diagnosis and comparisons (see also Table 2).—Eutropis

alcalai sp. nov. can be distinguished from its closest relative, E.

rugifera, by its smoother head scales, with light embossing only,

and keels limited to posterior margins of parietals, temporals

and nuchals (vs. rugose to strongly keeled in E. rugifera), by

absence (vs. presence) of contact between the postmental and

second infralabial, by the presence of 29–32 (vs. 21–26)

subdigital lamellae under the 4th toe, by the presence of seven

infralabials (six in E. rugifera), the presence of differentiation in

the precloacal scales series (two, medial precloacals enlarged,

transversely expanded and bordered on either side by two

Figure 2. (a) Consensus tree from Bayesian phylogenetic analysis of

twelve genes, summarizing current knowledge of phylogenetic

relationships among Eutropis species and placement of E. rugifera/E.

alcalai sp. nov. lineage. (b) Consensus tree from phylogenetic analysis

of four genes (ND2, BRCA1, RAG1, MC1R) illustrating divergence

among Philippine populations and E. rugifera populations from the

Sunda Shelf. (c) 16s gene tree illustrating relationships between E.

rugifera individual sampled from the type locality (Nicobar Island) and

three populations from Indonesia. Circles represents nodes where

posterior probability ≥0.99. Scale bar units are in number of

substitutions per site.

Character E. alcalai, new

species E. rugifera

PM–infra2 contact – +

4th toe lamellae 29–31 21–26

Differentiated

precloacals

2 medially enlarged 6 equivalent

scales

Infralabials 7 6

3rd & 4th finger lengths equivalent 4th longer than 3rd

Dorsal color pattern Very dark grayish-

brown, faint,

incomplete stripes

Chestnut–brown,

bright yellow

stripes

Chin & infralabials White Yellow-orange

Table 2. Distribution of diagnostic character states in selected charac-

ters among Eutropis alcalai, new species, and E. rugifera, its unam-

biguous most closely-related species. See Barley et al. (2020) for

diagnoses distinguishing the new species from all other Philippine

species of Sun Skinks in the genus Eutropis. “PM” = postmental scale;

“infra2” = second infralabial scale; see text for further explanation of

characters.



undifferentiated scales) in E. alcalai sp. nov. (vs. six equal sized

scales in E. rugifera), by equivalent length of 3rd and 4th fingers

(vs. 4th finger longer than 3rd), and by its white chin and

infralabial scales (vs. yellow to orange in E. rugifera).

Description of holotype.—The holotype is an adult male, with

hemipenes partially everted, in excellent condition, with a

midventral incision (portions of the liver removed and preserved

separately in 100% ethanol for genetic material) with an

apparent caudal autotomy scar 10 mm posterior to the vent (Fig

3b), followed by a largely regenerated tail (Figs 3a, 4b); snout–

vent length 70.1 mm, tail length (regenerated) 78.6 mm.

Body robust, relatively wide and slightly compressed,

limbs moderately developed, overlapping when adpressed,

hindlimbs conspicuously longer than forelimbs; head small and

short (its length 42.5% of axilla–groin distance when measured

snout–mandible, 54.7% when measured snout–auricular

opening); head narrow (its width 85.5% of length when

measured snout–mandible; 66.3% of length when measured

snout–auricular opening); head width 16.8% SVL; head barely

distinct from neck, triangular in dorsal aspect, compressed in

lateral view with snout rounded; head length 19.6% (snout–

mandible) and 25.3% (snout–auricular opening) of SVL, 42.6%,

54.8% of axilla–groin distance, respectively.

Head scales smooth and, except for posterior-most

supraoculars which are lightly striated but unkeeled; rostral

wider than high, contacting frontonasal; frontonasal as wide as

high; prefrontals large, not in medial contact but broadly

contacting first supraocular and anterior point of frontal; frontal

diamond-shaped, with elongate posterior point extension, not

contacting first supraocular but in broad contact with second

supraocular and frontoparietals; supraoculars four, second

largest; frontoparietals in broad medial contact, and also

contacting 2nd, 3rd, and 4th supraoculars anteriorly and parietals

and minute interparietal, posteriorly; interparietal without a

parietal eyespot; parietals in medial contact behind interparietal,

for distance equivalent to length of interparietal itself; parietals

large, strongly keeled on posterior margins, separated anteriorly

by interparietal, contacting 4th supraocular; nuchals in single

pair, strongly keeled. Lateral head scales lightly embossed;

nostril pierces small, trapezoidal nasal at its center (nostril

completely enclosed); nasals widely separated, contacting rostral

anteriorly, supranasals dorsally, anterior loreal posteriorly, first

supralabial ventrally; nasal makes point contact with second

supralabial on right, but not left; postnasals tall, curving forward

slightly above nasal, frontonasal and prefrontal; loreal single,

large, broader than high, contacting 3rd and 4th supralabials

ventrally, and prefrontals dorsally, but not contacting 1st

supraocular; second loreal in contact posteriorly with first

Figure 3. Eutropis alcalai sp. nov. (holotype PNM 9878; formerly KU

315013; adult male, SVL 70.1 mm), photographed before preservation

in dorsal (a) and ventral (b) views.

Figure 4. Eutropis alcalai sp. nov. (holotype PNM 9878; formerly KU

315013; adult male, SVL 70.1 mm), photographed in life: (a) close-up

of anterior body region; (b) full body; collected from Pasonanca

Natural Park, Barangay Pasonanca, on the outskirts of Zamboanga

City, Zamboanga Peninsula, western Mindanao Island. Photos: RMB.



supraciliary, minute scales in preocular position (enlarged

preoculars absent), and first of two enlarged suboculars,

separated from remainder of subocular series (3 unkeeled scales

posterior to orbit) by greatly enlarged 6th supralabial; eye large,

orbit diameter 26.1% head length when measured snout-to-

mandible (20.2% snout-to-auricular opening); supraciliaries six,

first slightly larger than others; enlarged pretemporals two,

keeled, both in contact with parietals; supralabials 7, 6th largest,

subocular, second and third longer than others; one

postsupralabial, keeled; one primary temporal, keeled;

secondary temporals two, lower much larger than upper, and

contacting parietal; tertiary temporals three, keeled,

approximately equal size, uppermost contacting parietals and

nuchals. Lower eyelid translucent, scaled, lacking transparent

unscaled window; lower eyelid scales tall, columnar;

infralabials seven, first two are equivalent in size, then

progressively increasing their width until sixth which is

approximately twice width of the first, followed by a smaller 7th

infralabial scale, same size as 1st and second infralabials; mental

twice as wide as deep; single large postmental in contact with

first infralabial; first pair of enlarged chin shields in contact,

following postmental and contacting 1st and 2nd infralabials;

second row of chin shields separated by a single median scale,

contacting 2nd and 3rd infralabials dorsally; subsequent chin

shields and gular scales equivalent in size, not transitioning to

larger ventral body scales until sternum; auricular opening

small, punctiform, round, its diameter 44.4% eye diameter,

tympanum deeply recessed; two small lobules present on

ventral edge of auricular opening.

Dorsal and lateral body scales, and those of proximal half

of limbs (humeral segment of forelimbs and femoral portions of

hindlimbs) strongly keeled, imbricate, without apical pits. Keels

prominent from posterior half of parietal scales, nuchals, and

remaining body; parietals and nuchals each with 8–10 keels;

nape and body scales with 4–6 prominent keels (mucros) per

scale, for full length of body; most middorsal scales each with

four strong keels, flanked on either side with weak keels; keels

arranged in longitudinal rows, end to end, from posterior margin

of each scale to anterior margin of next; lateral keeled scales

transition slightly to less-keeled scales at ventrolateral body

regions, and eventually to smooth midventrals; first two rows of

ventrals (at ventrolateral region) slightly keeled; posterior

margin of dorsal and lateral scales more strongly keeled than

anterior margins of each scale, producing keeled projections

(mucros), posteriorly from each scale, giving posterior edge of

each scale a crenulate margin, due to projecting keel points

(mucros); ventrals smooth (with striae), same size as dorsals

and lateral body scales; transverse scale rows around midbody

28; paravertebrals in 33 rows from parietals to base of tail (point

equivalent to above vent); 22 rows between midpoints of dorsal

limb insertions; 43 ventral scales from postmental to vent (23

between midpoints of limb insertions); two greatly enlarged,

laterally expanded precloacals, overlapped on either side by two

undifferentiated scales in lateral precloacal position.

Scales of dorsal distal portions of limbs same size as

ventral limb scales; keels continue outer surface of radial

segment of forelimbs (inner forearm scales smooth), before

transitioning to smooth scales on dorsal surface of hands and

fingers; keels continuously distributed through tibial segments

of hindlimbs, all the way to dorsal surfaces of foot; relative

length of fingers: IV = III > II > V > I; dorsal surfaces of fingers

with one row of smooth scales; proximal ends (one or two

phalangeal elements) with additional row; subdigital lamellae

smooth, slightly transversely expanded, widest at base of each

digit; each finger terminating in moderately recurved claw;

palmar surface of hands with non-imbricate, smooth, convexly

rounded, juxtaposed; single enlarged, raised scale present on

posterolateral edge of palm; relative length of toes: IV > III > V

> II > I. scales on dorsal surfaces of toes variably scaled, with

two rows of keeled scaled on proximal two phalanges of 2nd

through 5th toe, and proximal first toe, and all distal dorsal toe

surfaces covered by single rows of smooth scale; subdigital

lamellae of toes moderately transversely expanded, smooth,

numbering 29 under 4th toe; subdigital lamellae conspicuously

more expanded and widest (~1.5–2 times wider) at phalangeal

articulations; toes terminating in large, recurved claws; plantar

surface of foot with non-imbricate, convexly rounded,

juxtaposed scales; four differentiated, large subcylindrical scales

on the heel.

Tail cylindrical at base, not original, with autotomy scar

and subsequent regenerated regrowth to approximate length

equivalent of SVL, approximately 2/3 anticipated original tail

length; regenerated portion of tail much more slender than

inferred original tail width (Fig. 3a), median subcaudal row

transversely expanded, wider than subcaudals anterior to

autotomy scar (Fig. 3b).

Measurements of holotype (in mm).—SVL 70.1; forearm length

19.1; femur length 13.4; tibia length 13.1; foot length 16.4; head

length 13.8; snout length 7.4; length of 4th toe 11.6; head width

11.8; eye diameter 3.1; auricular opening 1.9; axilla–groin

distance 32.5; eye–tympanum distance 5.6; eye–nostril distance

4.3.

Coloration in life.— Dorsal surfaces of head, neck and anterior

trunk dark fawn (Köhler’s [2012] color 258) with cinnamon

highlights (255, 260) on neck and glaucous (289) to grayish

horn (268) on snout; posterior trunk surfaces darker, glaucous



dark brown (291) to burnt umber (48); dorsum with three

interrupted series of longitudinal, body-length stripes; similar

but distinct dorsolateral stripes on each side; on anterior

portions of body, longitudinal stripes are orange-rufus (56) to

dark salmon (59), and these fade to less vibrant sayal (41) to

mikado brown (42) by posterior trunk regions, where they are

barely ascertainable from background dorsal pelvic region

coloration; in anterior portions of trunk, distinctiveness of the

five dorsal, longitudinal stripes is heightened by increased

contrasting jet black (300 ocelli patterning, with each black

marking tightly coupled to with bright chamois (84) to straw

yellow (53) markings (Figs. 3a, 4b), some of which are confined

to single troughs between individual scale keels.

Sutures surrounding the outer perimeter of each scale on

dorsal and lateral head surfaces demarcated with jet black

pigment (Fig4a); supraciliaries and circumorbital minute scales

bright straw yellow (53); lateral nuchal region, axilla-groin

region (flanks), and lateral caudal surfaces (anterior to

autotomy; Fig. 4b) olive- (265) to smoke-gray (256);

regenerated dorsal and lateral tail surfaces jet black (300);

aggregation of black-and-chamois markings present above

forelimb insertion (Fig 4a) but not hindlimb; a sharp light

grayish-brown above–white below ventrolateral transition

present throughout head, neck, and trunk surfaces (Fig. 3b, 4a);

forelimbs and hind-limbs generally darker ground color, amber

(51) on forelimbs, dark grayish brown (284) on hindlimbs, with

distinct jet black (300) margins among individual dorsal limb

scales (Fig4a); dorsal surfaces of hand and foot similar to limbs;

dorsal surfaces of digits distinctly lighter, with brighter pearl

gray (290) highlights transversely alternating with sepia black

(286) coloration distally and terminating with Payne’s gray

(293) claws.

Ventral body color bright smokey white (261) to pale buff

(1) under head and throat, darkening and becoming more

yellowish (light buff 2) by posterior ventrum and distinctly

yellowish (pale horn 11) posterior to yellowish (light ocher 13)

cloacal opening (overlying precloacal scales); margins between

ventral scale rows very light pale bluish gray (287) giving

appearance of seven or eight faintly, smokey strips running

longitudinally, the length of the body (Fig. 3b), especially

evident on chin and throat; tail posterior to autotomy scar pale

bluish gray (287) to pale neutral (296), with increasingly dense

aggregation of black pigment condensing by tail’s black

subcaudal tip coloration; palmar surfaces of palm, plantar

surfaces of feet, and proximal subdigital portions of digits light

neutral gray (297), fading progressively to jet black (300) by

terminal phalanges and terminal claws of digits (Figs. 3b, 4a).

Iris surrounding circular pupil flesh ocher orange (57) to light

pratt’s rufus (71).

Coloration in preservative.—As with most species of Eutropis,

our specimens of Eutropis alcalai sp. nov. have demonstrably

faded, and lost brighter coloration and contrasting colors in

preservative, even when kept (in this instance, for more than a

decade) in complete darkness at constant temperatures and in

ethanol concentration. In preservative, the holotype is brownish-

olive (276) with dark neutral gray (299) dorsal and dorsolateral

longitudinal body stripes, offset by jet black single scales and

spots, each tightly juxtaposed with beige (254) markings; dorsal

surfaces of limbs are not noticeably different from dorsal body

surfaces; ventral surfaces cream white (52) with pearl gray (262)

laterally, and light lilac (221) scale margins on ventrolateral

transitions with flanks; ventral surfaces of limbs, palmar surface

of hand, and plantar surface of foot cream white (52) with pale-

to light (296, 297) gray subdigital lamellae of digits.

Variation.—A summary of variation in the type series is

presented in Table 3. KU 321834 has a substantial portion of its

original tail, indicating that when it has not been autotomized

and regenerated, the tail typically tapers gradually. In

preservative, dorsal surfaces of one paratype differs from the

holotype by being raw umber (280; paratype KU 321834)

whereas ventral surfaces of both paratypes is pale mauve (204)

with individual scale margins marked by dark blue gray (194);

both paratypes (KU 321833 and 321834) both have ventral

sternal regions cream white (52), and KU 321834’s original

subcaudal coloration is pale buff (1).

Distribution.—This species is only known from Pasonanca

Natural Park near Zamboanga City at the southwestern tip of the

Zamboanga Peninsula. A closely related species (E. rugifera)

occurs on Borneo (among other islands of the Sunda Region),

and although neither species has been collected from the Sulu

Archipelago, one of them may occur on its larger islands.

Habitat and natural history.—No detailed, field based natural

history studies of the new species have been performed but

given its conservation significance and its unique biogeographic

status as an endemic species of extreme southwestern Mindanao,

ecological studies of habitat use and requirements, behavior,

activity, and diet would all be very informative. Although little

is known about the natural history of E. alcalai sp. nov., it

clearly shares some aspects of its biology with E. rugifera in

being “uncommon” and “forest adapted” (Karin et al. 2017;

Amarasinghe et al. 2017), which constitute a challenge for

future ecological studies. Other inferences that are likely safe to

extrapolate from E. rugifera include our assumptions that E.

alcalai sp. nov. is diurnal, a generalist insectivore, most likely



Specimen: PNM 9878 KU 321834 KU 321839

(holotype) (paratype) (paratype)

Sex male male juvenile

SVL 70.1 64.4 46.5

Tail length 78.6 regenerated 27.8 autotomized 36.0 autotomized

Forearm length 19.1 17.6 11.8

Femur length 13.4 12 7.9

Tibia length 13.1 11.45 7.8

Foot length 16.1 14.7 11.8

Head length (mandible) 13.8 12.9 9.5

Head length (auricular) 17.8 14.7 11.5

Snout length 7.4 6.8 5.8

4th toe length 11.6 10.7 6.5

Head width 11.8 11.3 8.2

Eye diameter 3.6 3.1 2.2

Auricular opening 1.6 1.4 1

Axilla–groin distance 32.5 30 22.2

Eye–auricular opening 5.6 4.7 4.1

Eye-nostril 4.3 4.5 4.2

Ventrals: total 43 45 43

Ventrals: limb insertions 23 24 23

Dorsals: total 22 23 23

Dorsals: limb insertions 33 34 34

Midbody scales 29 29 30

4th tow lamellae 29 32 29

Table 3. Variation in the type series of Eutropis alcalai, new species. See text for further explanation of multiple ways head length,

paravertebrals, and ventrals were recorded.



reliant on cool forest floor arthropods found in the leaf litter and

herbaceous layer of vegetation, in lowland primary forest and/or

mature secondary forests (Das 2004; Grismer 2011;

Amarasinghe et al. 2017). In the protected lowland original

forests of Pasonanca, RMB and MBS observed the new species

moving through sun spots on the otherwise relatively dark,

humid forest floor (07:00–10:00 am; Fig. 5). In addition to the

holotype and paratype localities, several specimens were

observed on the forest floor near the river at 6.9922333°

N, 122.0604333°E. In several instances, individuals were

observed as they darted rapidly under leaf litter when disturbed

by approaching people, and another took refuge under bark and

other woody debris when pursued. When captured, the new

species exhibited anti-predatory behaviors/adaptations: it bit

while twisting its body in an “alligator roll” maneuver,

defecated, and easily lost scales when grasped (RMB and MBS,

personal observation).

Etymology.—We take great pleasure in naming this distinctive

new species for our colleague Angel C. Alcala, in recognition of

his numerous foundational contributions to the natural history,

systematics, ecology, and conservation of Philippine lizards of

the family Scincidae (Alcala and Brown 1966, 1967; Alcala

1970; Brown and Alcala 1956, 1961, 1963a,b, 1980, 1986).

Suggested common name: “Alcala’s Quinque-carinate (Five-

keeled) Sun Skink,” or “Alcala’s Rough-scaled Sun Skink.”

Discussion

The Zamboanga Peninsula of Western Mindanao in the

Philippines has an enigmatic geologic history that has been

subject to debate (Lambeck and Chappell 2001; Hall 2002;

Yumul et al. 2003; Padrones et al. 2017). It appears to have had

an ancient geologic origin much further west, closer to the

Sunda Shelf, before this exposed, originally continental crust

fragment moved eastward and accreted to the remaining

Mindanao Island landmass (Hall 2009; Padrones et al. 2017).

Given the estimated age of the divergence of E. alcalai sp. nov.,

it is conceivable that these geological processes potentially

contributed to, or facilitated, colonization of the southern

Philippines from the Sunda Shelf, as has been hypothesized in

other species (Clouse et al. 2011; Brown et. al. 2013). Genetic

data suggest that E. alcalai sp. nov. diverged from populations

of E. rugifera on the Sunda Shelf more than 10 mya (Karin et al.

2017), providing extensive time for these lineages to embark on

independent evolutionary trajectories (Gavrilets 2000; Coyne

and Orr 2004). Divergence among the remaining populations of

E. rugifera in Sundaland are much shallower and consistent with

them being intraspecific, albeit highly structured (Karin et al.

2017). The close relationship between the type locality E.

rugifera populations on Nicobar Island and the Sumatran

populations illustrate a biogeographic relationship that has been

identified in other species as well (Mani 1974; Das 1999; Teynié

et al. 2010; Ganeshaiah et al. 2019). Our phylogenetic results

also highlight a novel sister relationship between E. rugifera/E.

alcalai sp. nov. and E. tytleri, a result that is biogeographically

compelling given that E. tytleri is endemic to the Andaman

Islands which are thought to have shared a similar geological

history to the Nicobar Islands (Ripley and Beehler 1989).

Eutropis Taxonomic Diversity

Eutropis taxonomy remains in a state of flux. Genetic data

are lacking for several taxa and, thus, assessing the taxonomic

status of rare or poorly known, seldomly collected Eutropis

species remains a challenge. Genetic material is not available in

publicly accessible natural history collections for E.

andamanensis (M.A. Smith 1935), E. chapaensis (Bourret

Figure 5. Characteristics of vegetation in low elevation primary forest

of Pasonanca Natural Park, at the type locality of Eutropis alcalai sp.

nov. Photo: RMB.



1937), E. darevskii (Bobrov 1992), E. floweri (Taylor 1950), E.

gansi (Das 1991), E. innotata (Blanford 1870), E. madaraszi

(Méhelÿ 1897), E. quadratilobus (Bauer & R. Günther 1992),

E. tammana Das, da Silva & Austin 2008 and E. englei (Taylor

1925) due to the fact that many of these species have not been

encountered by biologists since their original discovery (but

note the recent discovery of the latter by Pitogo et al. 2020).

Other species such as E. dattaroyi, E. lankae, E. lewisi, and E.

resetarii were recently described or elevated primarily on the

basis of morphological characters, without reference to genetic

information. Genetic data for the remaining lineages are largely

limited to a handful of genes used to assess phylogenetic

relationships (Fig. 2; Supporting Information). Only in the

exceedingly common species, like E. multifasciata, has

sufficient sampling accumulated to allow for fine-scale

examination of population-level genomic variation (Barley et al.

2015b) though phylogeographic studies of widespread Eutropis

species through international collaboration are beginning to lead

to a much clearer understanding of Eutropis diversity (Barley et

al. 2015a; Datta-Roy et al. 2015; Karin et al. 2017).

Following resolution of many of the systematic problems

in the Philippine radiation, another major taxonomic challenge

within this group is in the E. macularia complex. The type

locality of E. macularia (Blyth 1853) was restricted to

Bangladesh by Taylor and Elbel (1958) and the complex

includes the species E. austini Batuwita 2016, E. clivicola

(Inger et al. 1984), E. allapallensis (K.P. Schmidt 1926) E.

greeri, E. madaraszi and E. tammanna (Fig. 2a). Barley et al.

(2015a) demonstrated that populations from the rest of

mainland Asia are not closely related to populations from India

near the type locality (Rangpur) and that these mainland

populations represent at least two species based on the genetic

data (a result that is congruent with the karyotype work of Ota

et al. [2001] on the populations from Thailand). How this

taxonomic information relates to the three subspecies of E.

macularia described by Taylor and Elbel (1958) is unknown.

Additionally, because the data presented in the original

description of E. tammanna (Das et al. 2008) are not publicly

available on GenBank, it is unclear how this species is related to

other lineages in the complex that have been identified in

subsequent, more comprehensive studies.

Biogeographical and conservation significance

Although it is tempting to interpret the apparent absence of

a Eutropis rugifera complex species (E. alcalai sp. nov. or E.

rugifera) in the Sulu Archipelago (Fig. 1) or farther up the

Zamboanga Peninsula and western mainland Mindanao, we

hesitate to do so for the simple reason that negative species

occurrence data are fraught with assumptions and pitfalls, which

could be explained by insufficient sampling or non-

comprehensive field surveys, which may be needed to

adequately characterize terrestrial vertebrate faunal assemblages

(Brown et al. 1996, 2000, 2012; Devan-song and Brown 2012;

Oliveros et al. 2011; Siler et al. 2011; Sanguila et al. 2016).

Nevertheless, the estimated divergence of E. alcalai sp. nov.

from E. rugifera appears to have been ancient (16–10 mya;

Karin et al. 2017 ) and, as such, the establishment of an

evolutionary lineage in the Zamboanga Peninsula (itself an

ancient crustal fragment, and part of the geological component

known as the Palawan Microcontinent Block; Dimalanta et al.

2009; Yumul et al. 2009b; Zamoras et al. 2004, 2008; Padrones

et al. 2017) could be related to a seldom-considered, but

increasingly invoked mode of faunal transport—paleotransport

via movement of crustal fragments of continental origin

(Blackburn et al. 2010; Siler et al. 2012; Brown et al. 2016).

Distinguishing between this hypothesis and that of long-distance

overwater dispersal versus island-hopping through the Sulu

Archipelago faunal corridor/filter zone (Inger 1954; Diamond

and Gilpin 1983; Brown et al. 2013a; Brown 2016) is beyond

the scope of the presently available data, but presents an

intriguing challenge for future biogeographic inquiry in the

southern Philippines. We interpret the presence of a largely low-

elevation, forest obligate, endemic scincid lizard, with the

entirety of its geographical distribution limited to Pasonanca

Natural Park, at the end of the Zamboanga Peninsula, as a high-

value target species for conservation. Such species convey the

supreme importance of Pasonanca’s low-elevation climax

rainforests and formal protected areas as a shining example of

the value of forested surface catchment watersheds for the

preservation of Philippine terrestrial vertebrate biodiversity.

IUCN Species Status of Eutropis alcalai sp. nov.

Eutropis alcalai sp. nov. should be classified under the

IUCN Red List Status of Data Deficient (IUCN 2012). The

known localities for this new species fall within a very small

range, which could be interpreted as “range restricted” and a

higher threat status. However, there have been no sustained

efforts aimed at detecting this species in the region over multiple

years, and no data exist on abundance or population trends. It is

possible that the species has a broader distribution in the

Zamboanga Peninsula and possibly western Mindanao or the

Sulu Archipelago (in particular on Basilan Island). Eutropis

alcalai sp. nov. also occurs in one of the most threatened habitat

types in the Philippines: lowland dipterocarp forest (Kummer

1992; Bankoff 2007). Therefore, the species may be benefited

by landscape/ecosystem-level conservation initiatives, although

it is crucial that efforts are made to assess this species

conservation status in the future with additional empirical data.



Although widespread, E. rugifera is rarely found in disturbed

areas (Grismer 2011), which may suggest it is relatively

intolerant of anthropogenic impacts compared to other Eutropis

species. Based on our current knowledge, it seems likely the

same is true of E. alcalai. If the new species is indeed relictual

and largely restricted to the watershed reservation in Pasonanca

Natural Park (~12,000 ha), it would likely qualify under a

threatened category on the IUCN Red List.

IUCN Species Status of other Philippine Eutropis

In light of a recent taxonomic revision (Barley et al. 2020),

we also provide IUCN Red List assessments for all other

Philippine Eutropis here.

Eutropis bontocensis.—Based on Taylor’s original

description (Taylor 1923), E. bontocensis was initially thought

to be restricted to high elevation habitats and endemic to the

Cordillera Mountains in northern Luzon. However, recent

research has demonstrated that it also occurs on numerous small

islands north of Luzon (Oliveros et al. 2011; Barley et al. 2013).

These habitats have experienced considerably less

anthropogenic impacts than others in the region. Historical

populations in Baguio have likely declined or been extirpated

due to urbanization, however, surveys by AJB in 2012 found

this species to be common along road cuts near Bontoc,

suggesting this species tolerates disturbance well and probably

remains abundant in many areas. Thus, this species should be

considered Least Concern at present.

Eutropis borealis.—Eutropis borealis is broadly

distributed across the northern and central Philippine Islands,

with populations in the Visayan Islands being somewhat

divergent from the northern Philippine populations (Barley et al.

2020). Surveys over the past decade by RMB and AJB have

found this species to be abundant in many low elevation

habitats and to tolerate disturbance well (e.g., they are

commonly found in agriculture and residential areas), so we

assign this species a status of Least Concern.

Eutropis caraga.—Eutropis caraga is broadly distributed

across the southern Philippine Islands with populations from

Siargao and Dinagat being somewhat genetically divergent from

populations across the rest of the species range (Barley et al.

2020). Recent survey work by RMB has found the species to be

common across of range of elevations and to tolerate

disturbance well (having been reported from agricultural and

residential areas near forest), so we consider this species to have

a status of Least Concern.

Eutropis cumingi.— Eutropis cumingi is broadly

distributed across Luzon Island, as well as numerous small

islands in the northern Philippines including Lubang, and the

Batanes and Babuyan Islands (Brown et al. 1996; Devon-song

and Brown 2012; Barley et al. 2020). Higher elevation

populations in the Cordillera Mountains are genetically

divergent from the other populations on Luzon, and the

investigation of mid-elevation contact zones would be valuable

to understand patterns of gene flow. Recent surveys by RMB

and AJB have found this species to be common in parts of

Luzon, including in highly disturbed habitats (e.g., on the

Ramon Magsaysay Technological University Botolan Campus).

We assign them a status of Least Concern.

Eutropis cuprea.—Eutropis cuprea is a poorly known

species, currently having only been documented from a single

locality in southwestern Mindanao (Barley et al. 2020). The

region is logistically challenging to work and this species is

difficult to distinguish from the more widespread species E.

caraga that also occurs in the region, so it is possible that further

survey work would demonstrate that the species has a larger

range in southwestern Mindanao than is currently known.

However, the type locality (Tampakan) is also the site of a large

and controversial mining project that was recently extended. We

assign this species status to be Data Deficient at present,

however, if it is indeed endemic to this small region of

Mindanao (and particularly if it is sensitive to anthropogenic

disturbance), the species likely deserves to be elevated to a

threatened status (in this case “Near Threatened”).

Eutropis gubataas.—Eutropis gubataas is known from

northern Luzon and the Babuyan Islands (Barley et al 2020).

While the region is relatively large, its distribution is relatively

poorly understood, particularly on Luzon where it has been

documented only at several, scattered, upland localities. Survey

work by RMB suggests it is substantially less abundant than the

morphologically similar and sympatric congener E. borealis. It

appears to be at least somewhat tolerant of disturbance (having

been collected in agricultural and residential areas near forests)

and occurs in at least some protected areas in northeastern

Luzon (e.g., Aurora Memorial National Park). Thus, we

tentatively assign this species a status of Least Concern, but

suggest that additional survey data would be valuable to

understanding this species and any conservation management

considerations.

Eutropis indeprensa.—The distribution of E. indeprensa

was recently restricted to the islands of Mindoro and

northeastern Borneo (Barley et al. 2020). Given that, one would

also expect this species to occur on Palawan, though only the

morphologically similar congener E. sahulinghangganan has

been documented from the island. Recent collections of the

species are primarily from low elevation, secondary growth

forest. Further work is needed to understand population trends

and tolerance to disturbance, though we tentatively assign the

species a status of Least Concern.



Eutropis islamaliit.—Eutropis islamaliit is an intriguing

species from a biogeographic perspective. It is known from

relatively few specimens from scattered localities across

Semirara, Lubang, and Samar Islands in the Philippines, and

Turtle Island, in Sabah, Malaysia (Barley et al. 2020). The fact

that the species is that broadly distributed, but known from so

few specimens is surprising, with the majority of specimens

having been collected in primary and secondary growth forest.

Perhaps it is more of a habitat specialist or relictual species

(given its presence on several small offshore islands) than is

currently appreciated, athough it is worth noting that recent

surveys by RMB on Samar found populations that were

sympatric with multiple other morphologically similar species

of Eutropis. Further work is needed to understand population

trends, abundance, and tolerance to disturbance; we tentatively

assign this species a status of Least Concern, primarily because

of its apparently broad distribution.

Eutropis lapulapu.—This species was recently described

from populations that had previously been assigned to E.

indeprensa (Barley et al. 2020). The species has a broad

distribution across numerous islands in the central and southern

Philippines where it occurs in a broad range of habitats and

appears to tolerate disturbance well (having been collected in

agricultural and residential areas). Therefore, we assign E.

lapulapu a status of Least Concern.

Eutropis multicarinata.—This species distribution was

recently restricted to encompass populations in northeastern

Mindanao, Samar, Leyte, and Dinagat Islands (Barley et al.

2020). It appears to inhabit a range of habitats in the region,

though it has long been confused with the recently described,

more widespread species E. caraga, which is morphologically

very similar. Data are needed on abundances and tolerance to

disturbance, although here we assign E. multicarinata a status

of Least Concern.

Eutropis sahulinghangganan—Eutropis sahulinghangga-

nan appears to be endemic to the island of Palawan (Barley et

al. 2020), although we would expect it to eventually be recorded

on satellite islets including the Balabac Island group (to the

south), as well as Busuanga, Coron, and Culion (to Palawan’s

north). Collections of the species are limited, but it is reported

from a variety of low and higher elevation forest types on

Palawan Island proper. Although information is needed on

population abundances and tolerance to dispersal, these habitats

are relatively abundant on the island (which is considered a

protected area), and therefore we assign it a status of Least

Concern.

Eutropis sibalom.—Eutropis sibalom is known only from

several specimens collected from low elevation, secondary

growth forest in southwestern Panay Island (Barley et al. 2020).

Virtually nothing is known about its natural history, population

trends, the extent of its distribution, or tolerance to disturbance.

We assign the species a status of Data Deficient. It occurs in at

least one protected area (Sibalom Natural Park), though surveys

are needed to determine if the species occurs more broadly

across the island of Panay, or if it is restricted to the limited area

from which it is currently known.

Acknowledgements

In addition to our field companions J. B. Fernandez, C. D.

Siler, C. Infante, C. Oliveros, J. Menegay, A. C. Diesmos, and J.

W. Phenix, who we thank for their company and good humor,

we thank Angel C. Alcala for his many years of support,

guidance, and (together with the late Walter C. Brown), for

serving as an inspiration for our team—by setting an example

with their career-long, ‘role model’ of an international academic

collaboration. We thank the staff and management of the

Zamboanga City Water District, the Pasonanca Natural Park

Protected Area Management Board, Golden Buddha Security,

and DENR Region IX office for logistical support, for assistance

in processing regional export permits, and for hosting our visits

to Zamboanga; special thanks are due to M. Dela Cruz, A.

Baysa, A. Adorable, D. Melana, M. Layson, E. Callanta, T.

Gadon, M. Tee, G. Fernandez, L. Alejo, E. Toribio, L. Sorsone,

L. Narag, A. Rojas and A. Braulio. We thank K. Ukuwela for

providing taxonomic advice. We acknowledge financial support

for field work (US National Science Foundation Grant, DEB

0743491, to RMB) and central Manila DENR and the

Biodiversity Management Bureau for granting our Gratuitous

Permits to Collect biological specimens (2007–2012); live

animal handling protocols were approved by KU’s Institutional

Animal Use and Care Committee (IACUC AUS 185-05 to

RMB). Phylogenetic analyses were performed using the

CIPRES Science Gateway.

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