Brachymeles gracilis

Brachymeles gracilis (Fischer, 1885)

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Overview

Biology

Brachymeles gracilis likely represents a complex of morphologically similar species. Over the last several years, an effort to understand the diversity of this genus has resulted in a doubling of the species diversity, with many of the previously recognized species complexes being revised. To date, Brachymeles gracilis remains a widespread species spanning islands of the Mindanao Pleistocene Aggregate Island Complex. It is a medium-sized species with five fingers and five toes. Populations vary greatly in digit numbers, scale counts, and numbers of presacral vertebrae. Two subspecies are currently recognized: Brachymeles gracilis gracilis and Brachymeles gracilis hilong. Brachymeles gracilis gracilis is recognized to occur throughout much of central and western Mindanao Island, while B. g. hilong is recognized from Samar, Leyte, and eastern Mindanao islands. The genus Brachymeles represents a unique group of semi-burrowing (semi-fossorial) lizards in that the group possesses species with a full spectrum of body forms, from limbed species with five fingers and five toes, to fully limbless species. Researchers are interested in the process and patterns behind the evolution of these drastic changes in body form. With the exception of two species from Borneo (B. apus) and Thailand (B. miriamae), all species of Brachymeles are endemic to the Philippines. This means they are found among the more than 7,000 Philippine islands and nowhere else in the world.

Author(s): Siler, Cameron
Rights holder(s): Siler, Cameron

Description

Brachymeles gracilis can be distinguished from congeners by the following combination of characters: (1) body size moderate (SVL 59.9–82.3 mm); (2) limbs pentadactyl; (3) Finger III lamellae four or five; (4) Toe IV lamellae 7–9; (5) infralabials six or seven; (6) supralabials six; (7) suparciliaries six; (8) supraoculars five; (9) midbody scale rows 24–30; (10) axilla–groin scale rows 44–50; (11) paravertebral scale rows 66–73; (12) pineal eye spot present or absent; (13) prefrontals contacting or not contacting on midline; (14) frontoparietals contacting or not contacting on midline; (15) mental/1st infralabial fusion absent; (16) enlarged chin shields in three pairs; (17) nuchal scales undifferentiated; and (18) auricular opening present.

Author(s): Siler, Cameron
Rights holder(s): Siler, Cameron

Conservation

Conservation Status

We have evaluated this species against the IUCN criteria for classification, and find that it does not qualify for Critically Endangered, Endangered, Vulnerable, or Near Threatened status. Brachymeles gracilis has been documented to have a broad geographic distribution and is quite abundant at all sampled localities. We therefore classify this species as Least Concern, LC (IUCN, 2010).

Author(s): Siler, Cameron
Rights holder(s): Siler, Cameron

Description

Size

SVL 59.9–82.3 mm

Author(s): Siler, Cameron
Rights holder(s): Siler, Cameron

Ecology and Distribution

Faunal Affinity

Brachymeles gracilis is recognized to occur in the Mindanao Pleistocene Aggregate Island Complex.

Author(s): Siler, Cameron
Rights holder(s): Siler, Cameron

Taxonomy

  • Senira bicolor (part) Gray, 1845 (synonym)
  • Eumeces (Riopa) gracilis Fischer 1885:85 (synonym)
  • Brachymeles gracilis Boettger, 1886 (synonym)
  • Brachymeles gracilis Boulenger, 1887 (synonym)
  • Brachymeles gracilis Taylor, 1917 (synonym)
  • Brachymeles gracilis Taylor, 1918 (synonym)
  • Brachymeles gracilis Taylor, 1922a (synonym)
  • Brachymeles gracilis Taylor, 1922c (synonym)
  • Brachymeles gracilis Brown & Alcala, 1970 (synonym)
  • Brachymeles gracilis Brown & Alcala, 1980 (synonym)

References

Brown, W. C. (1956).  A revision of the genus Brachymeles (Scincidae), with descriptions of new species and subspecies. Breviora. 54, 1-19.
Brown, W. C., & Alcala A. C. (1980).  Philippine Lizards of the Family Scincidae. (LawD., Ed.). Dumaguete City, Philippines: Silliman University Press.
Brown, W. C., & Alcala E. L. (1995).  A new species of Brachymeles (Reptilia: Scincidae) from Catanduanes Island, Philippines. Geological Society of America Bulletin. 101, 663-672.
Brown, W. C., & Rabor D. S. (1967).  Review of the genus Brachymeles (Scincidae), with descriptions of new species and subspecies. Proceedings of the California Academy of Sciences. 15, 525-548.
Hikida, T. (1982).  A new limbless Brachymeles (Sauria: Scincidae) from Mt. Kinabalu, North Borneo. Copeia. 4, 840-844.
Siler, C. D., & Brown R. M. (2011).  Evidence for repeated acquisition and loss of complex body characters in an insular clade of Southeast Asian semi-fossorial skinks. Evolution.
Siler, C. D., Balete D. S., Diesmos A. C., & Brown R. M. (2010).  A new legless loam-swimming lizard (Reptilia: Squamata: Scincidae: Genus Brachymeles) from the Bicol Peninsula, Luzon Island, Philippines. Copeia. 2010, 114-122.
Siler, C. D., Crombie R. I., Diesmos A. C., & Brown R. M. (2011).  Redescription of two poorly known slender skinks, Brachymeles bicolor and Brachymeles pathfinderi (Reptilia: Squamata: Scincidae) from the Philippines. Journal of Herpetology. 45(3), 355-369.
Siler, C. D., Diesmos A. C., & Brown R. M. (2010).  A new loam-swimming skink, Genus Brachymeles (Reptilia: Squamata: Scincidae) from Luzon and Catanduanes islands, Philippines. Journal of Herpetology. 44, 49-60.
Siler, C. D., Diesmos A. C., Alcala A. C., & Brown R. M. (2011).  Phylogeny of Philippine slender skinks (Scincidae: Brachymeles) reveals underestimated species diversity, complex biogeographical relationships, and cryptic patterns of lineage diversification. Molecular Phylogenetics and Evolution. 59, 53-65.
Siler, C. D., Jones R., Welton L. J., & Brown R. M. (2011).  Redescription of tetradactyl, Philippine slender skinks (Genus Brachymeles). Herpetologica. 67(3), 300-317.
Siler, C. D., Rico E. L., Duya M. R., & Brown R. M. (2009).  A new limb-reduced, loam-swimming skink (Reptilia: Squamata: Scincidae: Genus Brachymeles) from central Luzon Island, Philippines. Herpetologica. 65, 92-105.
Taylor, E. H. (1917).  Brachymeles, a genus of Philippines Lizards. Philippine Journal of Science. 12, 267-279.