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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