The following is provided by the courtesy of POLYPHEMOS which operates on the principal that scientific information should be freely accessible to all.

The provided information will be beneficial in better differentiating the two known subspecies of Corucia.

In the following, forgive the missing underlined scientific names and off center print. In the cut and pasting process, it proved to be unavoidable.


Subspecies comparison of the Genus: Corucia


Brian L. Schnirel and Sherri L. Jones
Leeway Corucia Research Center (LCRC)
Blenheim, S.C. 29516 U.S.A.




__________________________________________________________________________





Abstract:


Detailed measurements and observations differentiating the two subspecies of Corucia

zebrata , Corucia zebrata zebrata and Corucia zebrata alfredschmidti, are described including

new material not previously documented.



Key words: Corucia, Sclera, Parietal, Prefrontal, Rostral, Nasal

Introduction:



Corucia zebrata zebrata described and named (Gray, 1855) and Corucia zebrata

alfredschmidti described and named (Kohler, 1997) represent the two subspecies of

Corucia zebrata - the prehensile tailed monkey skink.

The common monkey skink (Corucia zebrata zebrata) hails from the larger islands of the

Solomon archipelago southeast of Buka and Bougainville. This includes Choiseul, Guadalcanal,

Isabel, Malaita, Nggla, New Georgia, Santa Ana, San Cristobal, Shortlands, and Ugi

(Balsai,1995). The North Solomon monkey skink (Corucia zebrata alfredschmidti) hails from

the North Solomons which are comprised of Bougainville and Buka (Kohler,1997).

Bougainville is by far the largest island in the archipelago and being on the northeast fringe

of these islands, supported the establishment of peripheral isolates evolving into the subspecies

alfredschmidti. This is supported by the sheer number and larger distribution of the subspecies

zebrata in the southeastern islands. The core population of Corucia zebrata zebrata appears to

be from Quadalcanal (Balsai, 1995). The allopatric subspeciation of the Genus: Corucia reveals

a larger size of Corucia zebrata alfredschmidti compared to Corucia zebrata zebrata. Indeed, a

semi-Wallace line appears to exist between Bougainville and Choiseul. "There is an affinity

along the lines of Bougainville - Choiseul, separated by the Bougainville strait, in which the

faunal differences are relatively distinct (faunal differences 86%)" (Green/Slade,1968). Other

animals show a size differential with the populations on Bougainville being generally larger than

that on Choiseul. The monkey faced flying fox (Pteralopex anceps) on Bougainville is also

larger (255-280 mm). On Choiseul, next to Bougainville, the population is smaller







(160-275mm) (E. Bowen-Jones 1997).

The differences between Corucia zebrata zebrata and Corucia zebrata alfredschmidti are

described here in detail which should aid in better appreciating the comparative differences

between the two subspecies. As such, identification will achieve a faster result. However,

once one has seen both Corucia zebrata zebrata and Corucia zebrata alfredschmidti, the

visual difference in size and body coloration alone is readily apparent, even from a distance.


Snout/Vent Length (SVL) & Length Overall (LOA)




common monkey skink
Corucia zebrata zebrata





SVL:

Average: Males = 250 mm

Females = 270 mm


Range: Males = 230 - 270 mm

Females = 260 - 280 mm


LOA:

Average: Males = 550 mm

Females = 582.5 mm

Range: Males: = 520 - 580 mm

Females: = 560 - 605 mm










North Solomon monkey skink
Corucia zebrata alfredschmidti



SVL:

Average: Males: = 320 mm

Females: = 330 mm


Range: Males: = 290 - 340 mm

Females: = 270 - 330 mm




LOA:

Average: Males: = 660 mm

Females: = 670 mm


Range: Males: = 630 - 680 mm

Females: = 640 - 690 mm




Number of individuals of equal proportions used in study: 96.

A noticable difference in size of neonates is also in evidence: (LOA)

Corucia zebrata zebrata averages about 11 1/2" (Langerwerf, 2006, Schnirel, 2001)

Corucia zebrata alfredschmidti averages just under 15" (Schnirel, 2004)




Czz / Cza neonate comparison:

Corucia zebrata zebrata LOA = 289 mm

Corucia zebrata alfredschmidti LOA = 370 mm


Note: Both subspecies of Corucia zebrata reproduce by viviparous matrotrophy with the birth
of a single very large neonate. Occasionally, twins are produced, there is one documented case of triplets (Langerwerf, 2003).


Number of young used in study: : 39.




Weight (Average)

Adult Neonate

Common monkey skink = 500 Grams 81 Grams
Corucia zebrata zebrata



North Solomon monkey skink = 845 Grams 173 Grams
Corucia zebrata alfredschmidti


Number of adult Corucia used in study : 96. , Number of neonate Corucia used in study : 39.

common monkey skink

Corucia zebrata zebrata

(Gray,1855)



Czz
Description:

Size:

Smaller size than Northern Solomon monkey skink (Corucia zebrata

alfredschmidti). Average adult: LOA = 572mm (22", SVL = 262mm (10".

Scalation:

Head
Scalation: The original description by Kohler indicates that common monkey

skinks possess five parietal scales. The arrangement has, from left to

right-head facing observer, parietal scale one and two larger and less

cramped in width than comparable parietal scales in the North Solomon

monkey skink (width/length ratio- parietal scale one = 9/13, parietal scale

two = 18/27). Parietal scales encompass nearly the entire left side of the

region (front facing away from observer) of the upper head. Parietal scale

three is positioned centrally comparable in position to parietal scale four in

the Northern Solomon subspecies. It is larger (length ratio Czz/Cza = 9/7,







Width ratio Czz/Cza = 7/5). Parietal scale three is triangular with the

tapered point directed towards the rear of the head (width/length ratio =

7/24). Parietal scale four is right of center. It is more round in shape (length

ratio Czz/Cza = 5/8, width ratio Czz/Cza = 7/9, width/length ratio = 7/8).

Parietal scale five is on the right edge of the head and positioned more to the

rear than the other four parietals (width/length ratio = 13/30). Unlike

the Northern Solomon subspecies, the common Solomon monkey skink

has no number six and seven parietal scales. The parietal description is a

guide however, and should not be taken as absolute except for the total

number. In practice, the head scales are as varied as fingerprints in size and

shape. The prefrontals of Corucia vary in size and number. Common

monkey skinks possess two to three.


Body
Scalation: Dorsal and ventral scales are in a different ratio. Common monkey

skinks are more elongated with a length/width dorsal scale ratio of 4/9.

Northern Solomon skinks have a length/width dorsal scale ratio of 6/9.

Length/width ventral scale ratio for the common subspecies is 3/7. The

Northern Solomon subspecies length/width ratio = 1/2.


Eyes:

Sclera: A consistent distinquishing feature separating the two Corucia subspecies







is scleral color. Corucia zebrata zebrata has a white sclera. Corucia zebrata

alfredschmidti has a black sclera.


Iris: The iris color can vary from dark green, green, greenish yellow, orange,

and jet-black. A green background iris can be stippled with brown or black

pigment. The green or yellow-green pigmented iris could be autosomal

dominant as is with a brown-black pigmented iris in humans. This means

only one copy of this gene from a parent is needed in order for a green-

yellow pigment to be manifested in the individual. For a total black

pigmented iris in a Corucia (which is the least seen); this would

signify the black pigmented gene would have to be contributed by both

parents to achieve this color phase. Unlike the Northern Solomon

subspecies, there is no establishment of iris color linked to specific islands

or cooresponding phenotypes with the common subspecies.



Body
Coloration:



Holotype
Description: The classic holotype description by John Edward Gray describes

Corucia zebrata zebrata as having prominent banding. The bands are







alternating dark brown-black/ green. The green portion can be of various

shades. The mid body bands are vertical to a twenty degree forward slope

as compared to Corucia zebrata alfredschmidti with a fifty degree forward

slope. Gray also described a play of colors effect from the body scales,

hence the origin of the scientific name. The Genus name Corucia derives

from the latin coruscus - definition: shimmering. Zebrata is a latinized

form of the word zebra; pertaining to the zebra-like banding. Black

spots are varied throughout the body. The green in the body is often

blended with brown. The locus typicus of gray's work with Corucia

was on San Cristobal.


Other
Phenotypes: Unfortunately, not enough research has been done on wild

populations on specific islands with Corucia zebrata zebrata. Certain

phenotypes may correspond to separate islands. The Leeway Corucia

Research Center has found that different phenotypes within Corucia

zebrata zebrata will breed with complete success. In other words, there

appears to be no genetic drift towards speciation to the point of non-viability

of the embryo.

All phenotypes can have black spot pigmentation throughout the body in

various sizes, numbers, and patterns. The spots may overlap. Dark green







body coloration may occur with little or no black pigmentation. This may coincide with the report of the darkest individuals coming from Malaita
(McCoy, 1980). There are individuals having incomplete banding. The
incomplete banding consists of blotches. The blotches are green to

greenish aqua. Some will have no banding or blotches period.

One phenotype from this category is an army green color often with little

or no black spots. Often, as previously indicated, the body is flushed

with patches of light brown at various parts of the body but in

addition, there can be brick red around the head. Yellow is generally less

prominent in Corucia zebrata zebrata than with Corucia zebrata

alfredschmidti. Some yellow can be seen usually in the throat or spotted

only on parts of the head compared to cases of almost full yellow on the

head of the North Solomon subspecies. In one documented case, a highly

pigmented (light and dark spots) female (LCRC/Czz/34) exhibits yellow

spots on the tail. To date, this is the only Corucia seen with this color

pigmentation in the tail region. Some common monkey skinks have white

on the head and throat (i.e.LCRC/Czz/36). The nasal and rostral scales

of all types are generally darker in color in Corucia zebrata zebrata than

with Corucia zebrata alfredschmidti. North Solomon monkey skinks have

a distinctive yellowish-cream color to the nasal and rostral scales which

appears striking in contrast to the generally turquoise head.

North Solomon monkey skink

Corucia zebrata alfredschmidti

(Kohler,1997)


Cza
Description:

Size: Larger size than the common monkey skink (Corucia zebrata zebrata).

Average LOA = 690mm (27", SVL = 335mm (13".


Head
Scalation: As based on Kohler, North Solomon monkey skinks possess seven

parietal scales. The arrangement has, from left to right-head facing

observer, parietal scale one and two smaller and more cramped in width

than comparable parietal scales in the common monkey skink (width/length

ratio: parietal scale one = 4/6, parietal scale two = 13/25). Parietal scale

three is smaller in length and width (width/length ratio = 13/16) than

comparable scale in Corucia zebrata zebrata (pointed towards the rear of

the skull). Parietal scale four is centralized and elongated with a bottleneck

appearance near vertical center (narrowest point width/length ratio = 2/19,

total width variation ratio = 4/17,). However, the original description of the

holotype and paratypes has no mention of parietal scale four ever pinched-








off completely rather than bottlenecked. The illustration in Salamandrae gives

the impression that the bottleneck configuration is standard. Head scales

actually vary in size and shape as much as the black pigment spots on the

body. In common observation, most specimens of Corucia zebrata

alfredschmidti have the pinced-off version. Parietal scale five is just right of

center rather than at the dextral edge as in the common monkey skink

(width/length ratio = 13/17). Parietal scale five is also more symmetrical in

shape and squarer than parietal scale five in the common monkey skink.

Parietal scale six (not found in Corucia zebrata zebrata) is comparable in size

and shape to parietal scale three (width/length ratio = 12/17). Parietel scale

seven (not found in Corucia zebrata zebrata) is elongated and more pointed

to the front of the skull (width/length ratio = 7/12). Parietal scale seven is at

the dextral edge of the head. Prefrontal scalation varies from two to four

compared to two-three in the common monkey skink.

In summation, head scales are not the best indicator of Corucia

subspecies classification. It takes a trained eye and much close up viewing to

get an accurate determination. The unwavering criteria to utilize is that

Corucia zebrata alfredschmidti has 2 more parietals (six and seven) than with

Corucia zebrata zebrata.










Body
Scalation: North Solomon monkey skinks have been described as having larger

ventral and dorsal scales than the common monkey skink (Kohler,1997).

The scales are larger in general due to the larger ultimate size of this

subspecies of Corucia. However, in a ratio comparison of width/length,

there is a difference as noted in the common monkey skink section.

LCRC research data shows that in a width/length ratio of dorsal scales,

North Solomon monkey skinks have a ratio of 6/9. Common monkey

skinks have a ratio of 4/9. The ventral width/length ratio is 1/2 for the

Northern Solomon monkey skink and 3/7 for the common monkey skink.


Eyes:
Sclera: As noted earlier, Corucia zebrata alfredschmidti has a black sclera and

Corucia zebrata zebrata has a white sclera. This is unvaried.



Iris: The iris color of Corucia zebrata alfredschmidti does not seem to vary

as much as in Corucia zebrata zebrata. The color is almost always a green-

yellow mix - at least in Corucia zebrata alfredschmidti from Bougainville.

However, Corucia zebrata alfredschmidti from Buka appear to have a more

intense green iris.











Besides the striking head color and larger ultimate size, the eyes of

Corucia zebrata alfredschmidti are another very prominent and stunning

attribute of this subspecies. The yellow-green iris coloration surrounded by

the black sclera makes this so.



Body
Coloration: The top of the head in the North Solomon Monkey skink is a striking

turquoise often suffused with yellow. This concurs with the holotype

description by Kohler. Most of the yellow is prominent in the throat and

chin region but may occur on top of the head as well in several areas including

the region around the ear openings. There has not been observed in Corucia zebrata alfredschmidti, a yellow spotted individual in the tail region like the

LCRC / Czz /34 specimen. From imports of highly questionable legal

passage but traced and personally seen, it appears that North Solomon

Corucia that hail from Buka differ from the main pennisula contingent in that

the Buka contingent of Corucia shows a light brownish component overlaying

the bright turquoise on the head. In addition, as mentioned, the iris is an

intense green. Otherwise, all other aspects of Buka Corucia zebrata

alfredschmidti are germane to that of Bougainville Corucia zebrata alfredschmidti. It would appear, that the Buka Corucia are a polytypic

variant but would not constitute a separate subspecies classification.

As with the common monkey skink, North Solomon monkey skinks

are found with and without banding. The banded individuals have central

bands that slope at a 50 degree angle. Common monkey skinks have a

0 - 20 degree angle to the transverse torso of the body. This has also been

noted by Burt Langerwerf of Agama International. The bands on the

North Solomon monkey skinks are a consistent light brown whereas

common monkey skinks are darker brown to black. The lighter brown

banding in contrast to the aqua bands gives a more faded appearance to the

North Solomon subspecies compared to the common subspecies. Blotched

North Solomon individuals are occasionally encountered. Both banded and

unbanded North Solomon monkey skinks may have black spots. Northern

Solomon monkey skinks have the light brown tone mentioned in the bands

often intermixed with the aqua of the body. Common monkey skinks often

have a brown wash with the green/aqua color of the body but the brown is

usually darker. All North Solomon monkey skinks have a distinctive

yellowish-cream color to the nasal and rostral scales in contrast to a darker

color in common monkey skinks as noted in the common monkey skink section.










The cream color of these scales also shows a significant contrast to the turquoise

color of the head of the North Solomon subspecies.






Kohler lists the holotype of Corucia zebrata alfredschmidti as holotypes SMF

77587 with locus typicus being the island of Bougainville (Mekamuri or North

Solomons). The Holotype resides in the Senckenberg Museum, Frankfort

Germany (Museum Franfort Senckenberg an lage 25 60325 Frankfort am main D.

Germany tel 49 06917542-0 fax 90691746238). The holotype is described as

being an adult Male.


The Paratype of Corucia zebrata alfredschmidti is listed as MTKD - 39481. The

paratype resides in the Staatiches Museum Fur tierkunole Augustus strasse 2

Dresden Germany. The Paratype is described as being unknown in gender.



The Leeway Corucia Research Center (LCRC) Studbook classification system is as follows:








LCRC / Czz / 34




LCRC = Corucia Research Center of individual




Czz = Subspecies classification Czz = Corucia zebrata zebrata

Cza = Corucia zebrata alfredschmidti




34 = Individual number at research center

Discussion:


Although Genetic drift of the peripheral isolates of the Corucia population

resulted in the subspeciation of Corucia zebrata alfredschmidti, the ecological

niche in this subspecies remained constant. This is based on a pattern in the

Scincidae where the more arboreal the species, the proportionally longer the

digits. A smooth, non-varying, numerical progression can be seen from species

of various niches based on anterior foot length (the junction of the ulna / radius

carpal bones to longest digit) divided by the snout to vent length (SVL). In the

case of Corucia, both subspecies occupy a high canopy arboreal niche with the

same numerical value.

Although no viable cross subspeciation has been documented resulting

in 'whatticles' (Jones, 1984), being subspecies, it is theoretically possible to

cross North Solomon Corucia with common Corucia. Balsai (1995) has

theorized that common Corucia from various islands have been genetically

apart enough based on miscarriages that have occurred in captivity.

However, many breeding centers have had great success rates in breeding of

this species of different phenotypes. The South Florida Corucia Research

Center had a 100% success rate of over thirty births. Agama International also

shows a positive record. Other factors may be the reasons for the

miscarriages resulting in slugs (miscarriages) or stillbirths other than genetic

incompatibility that need to be explored. For instance, improper








environmental conditions (humidity, temperature, diet, etc.), stress, disease,

exposure to toxins, the possibility of too much genetic closeness if the mated

pair came from the same island canopy and were closely related, etc. Other

than Corucia zebrata zebrata and Corucia zebrata alfredschmidti, there appear

no other candidates for subspecies classification. As such, genetic

incompatibilty between the common subspecies of Corucia is a topic that

requires further research. Although common Solomon monkey skinks may not

exhibit miscarrages due to genetic drift, it would be logical to conclude that

between subspecies (Corucia zebrata zebrata and Corucia zebrata

alfredschmidti), they could be enough apart that breeding between the two

would result in genetic misfires to some degree. This, of course, would be

based on the time honored rule of distinct speciation depending on a species

being unable to produce a viable species with another. Whether or not the

two subspecies straddle the fence of genetic compatibilty is also a future

topic of research.

To distinquish Corucia subspecies in summation, if one cannot see the

two subspecies in comparison or a photograph, look for the following. In

Corucia zebrata alfredschmidti, two extra parietal scales, or up to two extra

pre-frontal scales, a black sclera, bright turquoise head (in most cases), and in

banded individuals, a 50 degree slope in banding. In a visual comparison, look








for a reduced ratio in dorsal and ventral scale ratios of width/length of

Corucia zebrata alfredschmidti compared to Corucia zebrata zebrata. A larger

size of approximately 17%, a lighter brownish coloration - especially a faded

appearance in the banded individual, and a noticeable contrast between body

coloration and nasal and rostral scales - with the scales having a distinctive

yellow cream coloration.

References:


Balsai, Michael J.; 1995. Husbundry and breeding of the Solomon islands prehensile-
tailed skink (Corucia zebrata). The Vivarium, Escondido,
California, U.S.A. pp. 4-11.


Bowens, E.; Jones; 1997. Flying foxes on Choiseul (Solomon islands) - the need for
conservation. Oryx, Volume 31, July, Cambridge, U.K.
page 309.


Coburn, John; 1996. Prehensile tailed skinks. T.F.H. Publications Inc. Neptune City,
New Jersey, U.S.A. 64 pages.


De Vosjoli, Phillippe
1993. The general care and maintainence of prehensile tailed skinks.
Advanced Vivarium Systems Inc., Lakeside, Cailfornia, U.S.A.
57 pages.


Kohler, G.; 1997. Eine neue unterart des wickelshwanz skinkes Corucia zebrata
von Bougainville, Papua Neuguinea - Salamandrae, Germany
Volume 33, Issue 1, pp. 61-65.


Green, Slade; 1968. Island patterns in the Solomon islands bird fauna. Evolution,
Volume 11-Number 4, December, London, U.K. pp. 751-761.


Langerwerf, Burt; 2003. Agama International; Personal communication.


McCoy, Michael; 1980. Reptiles of the Solomon islands. Wau Ecology Institute,
Handbook No. 7:30. Papua New Guinea.


Parker, F.; 1983. The prehensile tailed skink (Corucia zebrata) on Bougainville
island, Papua New Guinea. Advances in herpetology and
evolutionary biology, Museum of Comparative Zoology,
Cambridge, Massachusetts, U.S.A. pp. 435-440.








Schnirel, Brian L. 2004. Seni biometric analysis on the extinct Scincidae species:
Macroscincus coctei. Polyphemos, Volume 2, Issue 1,
May, Florence, South Carolina, U.S.A. pp. 12-22.

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