Leeway Corucia Research Center (LCRC)



SENI biometric analysis on the extinct Scincidae species: Macroscincus coctei (underlined)





It has been determined that through mitochrondrial DNA research



that Macroscincus coctei has been linked to the Mabuya genus and may



both belong to the same clade. Evidence suggests that due to rafting



episodes, Mabuya species occupied the Cape Verde archipelago from



West Africa. By the Pleistocene, Macroscincus coctei had occupied the



northwestern group of islands and in a case of parallelism, Mabuya



villianti occupied the southern group of Cape Verde islands (Carrenza et



al.,2001). Both were large Scincids of a somewhat herbivorous nature



(based on dentition).



The Cape Verde Islands were denuded some five hundred years ago with



importation of domestic animals.



Working with an extant living relative, Mabuya striata sparsa, many



common features were noted. On this work submitted both



Macroscincus coctei and Mabuya striata sparsa had a SENI value of .13 ;



indicating a similar low canopy arboreal niche.





Abstract:





Macroscincus coctei, a giant member of the Scincidae, became



extinct before a proper study of it's lifestyle could be conducted.



The few scientific studies of this species that were done were made



after the ecosystem was vastly altered.





Using a designed biometric ratio, extant members of the



Scincidae were tested. A systematic numerical linkage of a given species



to a known ecological niche resulted. The technique was then utilized with



Macroscincus coctei to determine it's ecological niche.







The SENI is a ratio based on anterior foot length at the junction of the



ulna/radius-carpal bones to the longest digit divided by the snout to vent



length {SVL} (B. Schnirel, 2003). It had been determined that a



relationship seemed to exist between the length of certain body



proportions such as the anterior foot length and type of environment



common to a given Scincidae species. The more arboreal a skink



species, the larger the proportion. The SENI method can be a



useful in confirming the environmental niche, and possibly determining



the trophic level of extinct skink species unavailable for direct study.







Species (Extant) known Ecological Niche Seni

Scientific Name/

Common Name







Chalcides chalcides Subterranean .01

North African Worm Skink ( Deep-Burrower)



Chalcides sepsoides Subterranean .02

North African Ribbon Skink (Shallow-Burrower)



Eumeces scheideri Fossorial .06

Berber Skink



Tiliqua gigas Fossorial .06

New Guinea Blue-Tongue Skink



Hemisphaeriodon gerrardi Semi-Arboreal .11

Pink-Tongue Skink



Kabuya striata sparsa Arboreal .13

Kalahari Black Tree Skink (Low-Canopy)



Corucia zebrata zebrata Arboreal .17

Common Monkey Skink (High-Canopy)







Macroscincus coctei .13

Cape Verde Giant skink



Discussion:







The SENI biometric ratio has given a good numerical perspective of the differences



between Scincidae species in their lifestyle as well as appearance.







Since the initial development of the SENI biometric ratio in 2003 and the intial study



of the species described in this paper, the Leeway Corucia Research Center has



used this method extensively and it has given insight into our research with



the extant species: Corucia zebrata. In addition to C/A biometric ratio studies and



comparisons of SVL and LOA measurements, the SENI formula is one more tool for



comparison of Corucia zebrata with Macroscincus coctei and other members of the



Scincidae.





References:







Adler,G.H.

Austin,C.C.; 1995 Dispersal and speciation of skinks

amoung archipelagos in the tropical

Pacific ocean. Evolutionary

Ecology: pp 529-541.







Austin, C.C; 1995 Molecular and morphological

evolution in south Pacific lizards.

Herpetologica: pp.291-300.







Carrenza S, Parallel gigantism and complex

Arnold EN, colonization patterns in the Cape

Mateo JA, Verde scincid lizards: Mabuya and

Lopez-Jurado LF, Macroscincus (Reptilia Scincidae)

2001 reveled by mitochrondrial DNA

sequences. Proc Bilo.Sci Aug 7, 268

(1476), : 1595-1603.





Day, David; 1979 Vanished species. Gallery

Books,London,Great Britian:

pp. 254-255.







Grzimek, Berhard; Grzimek's animal life encyclopedia.

1975 Volume 6 Reptiles, Van Nostrand-

Reinhold Company, New York,

New York U.S.A.: pp.178-179.







Hartdegen, Ruston W. The green tree skink. Reptiles

2003 Magazine, Volume 11-Number 9,

September, 2003, Boulder, Colorado,

U.S.A.: pp. 42-50.







Honda, m. et al. Evolution of Asian and African

1999 Lygosomine skinks of the Mabuya group

(reptilia: Scincidae) a molecular

perspective. Zoological Science,

Volume 16, No. 6 pp. 857-1002,

December,1999







Pether, Jim; 2003 In search of Macroscincus coctei.

Reptiles Magazine, Volume 11-

Number 4, April, 2003, Boulder,

Colorado, U.S.A.: pp.70-81.







Walls, Jerry G.; Skinks: identification, care, and

1994 breeding. T.F.H. Publications,

Neptune City, New Jersey U.S.A.:

pp.52-58.





Sincerely,

Brian

LCRC

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