[Corucia zebrata zebrata (Gray,1855)]
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.
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