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The following is provided to benefit all institutions and Research Centers working with the subspecies: Corucia zebrata zebrata (underlined) and Corucia zebrata alfredschmidti (underlined)





LEEWAY CORUCIA RESEARCH CENTER (LCRC)





Courtesy of POLYPHEMOS (May, 2006)





Subspecies comparision 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 (underlined), Corucia zebrata zebrata(underlined) and Corucia zebrata alfredschmidti (underlined), are described including new material not previously documented.







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







Introduction:







Corucia zebrata zebrata (underlined) described and named (Gray, 1855) and Corucia zebrata alfredschmidti (underlined) described and named (Kohler, 1997) represent the two subspecies of Corucia zebrata (underlined) - 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 (underlined) 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 (underlined)











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 (underlined)







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



Corucia zebrata alfredschmidti (underlined) 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 (underlined) 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).





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 (underlined)

(Gray,1855)







Czz

Description:



Size:



Smaller size than Northern Solomon monkey skink

(Corucia zebrata alfredschmidti (underlined)).

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 (underlined) has a white sclera. Corucia

zebrata alfredschmidti (underlined) 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 (underlined) 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

(underlined) 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 (underlined).

Certain phenotypes may correspond to separate

islands. The Leeway Corucia

Research Center has found that different phenotypes

within Corucia zebrata zebrata (underlined) 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 (underlined)

than with Corucia zebrata alfredschmidti

(underlined. 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 (underlined)



(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

(underlined) has a black sclera and Corucia zebrata

zebrata (underlined) 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

(underlined)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 (underlined), 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)(Schnirel, 2004). 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 (underlined) and Corucia zebrata alfredschmidti (underlined, 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 (underlined) and Corucia zebrata alfredschmidti(underlined)), 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(underlined), 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 (underlined) compared to Corucia zebrata zebrata (underlined). 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.





Addendum:





The color, banding, blotches and spots mentioned are adaxial in general for both subspecies. The abaxial area (lower chest and belly region to vent) is void of bands and spots. It is generally a solid green or aqua.





References:





Balsai, Michael J.; 1995. Husbandry 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. (Underlined)

Polyphemos, Volume 2, Issue 1,

May, Florence, South Carolina, U.S.A. pp.

12-22.



Sincerely,

Brian L. Schnirel

LCRC



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