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Calamaria palavanensis INGER & MARX, 1965

IUCN Red List - Calamaria palavanensis - Data Deficient, DD

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Higher TaxaColubridae, Calamariinae, Colubroidea, Caenophidia, Alethinophidia, Serpentes, Squamata (snakes)
Common NamesE: Palawan Worm Snake 
SynonymCalamaria palavanensis INGER & MARX 1965: 134
Calamaria everetti BOULENGER 1894 (non BOULENGER 1893), (part.)
Calamaria palawanensis — GARCIA (pers. comm.)
Calamaria palavanensis — WALLACH et al. 2014: 140 
DistributionPhilippines (Palawan)

Type locality: “Palawan Island” [= Sulu Archipelago, SW Philippines].  
TypesHolotype: CAS 62151 
DiagnosisDiagnosis. Maxillary teeth modified; third and fourth supralabials entering orbit; preocular present; mental not touching anterior chin shields; paraparietal surrounded by 5 shields and scales; diameter of eye longer than ventral border of prefrontal; reduction to 4 dorsal scale rows separated from terminal scute by less than 14 subcaudals; a continuous light stripe on first scale row (Inger & Marx 1965: 135).

Description. Rostral broader than high, portion visible from above 2/3 length of prefrontal suture; prefrontal 3/4 length of frontal, touching first 2 supralabials; frontal hexagonal, 1.5 to 2 times width of supraocular, 3/4 to 5/6 length of parietal; parietal 1.5 to 1.66 times length of prefrontal; paraparietal surrounded by 5 shields and scales; nasal large, equal to or smaller than postocular; preocular present; neither ocular as high as eye; eye much greater than eye-mouth distance; 5 supralabials, third and fourth entering orbit, fifth the largest, first 4 subequal; mental triangular, not touching anterior chin shields; 5 infralabials, first 3 touching anterior chin shields; both pairs of chin shields meeting in midline; 3 gulars in midline between posterior chin shields and first ventral (Inger & Marx 1965: 135).

Body thickness index 0.007-0.025 (3 specimens); tail thick, tapering near end to point; dorsal scales reduce to 4 rows on tail opposite third to thirteenth subcaudal anterior to terminal scute (Inger & Marx 1965: 136).

Hemipenis forked near tip; sulcus spermaticus bifurcate, calyces papillate (1 specimen) (Inger & Marx 1965: 136).

Nine modified maxillary teeth (2 specimens) (Inger & Marx 1965: 136).

Ventrals; males, 174-181 (mean 177.3; N=3); females, 171-187 (mean 180.2; N=5). Subcaudals; males, 23-25 (mean 24.0; N=3); females, 16-20 (mean 17.5; N=4) (Inger & Marx 1965: 136).

Total length: males, 289-315 mm.; females, 125-323 mm. Ratio
of tail to total length: males, 0.081-0.093 (mean 0.086; N=3); females, 0.055-0.067 (mean 0.061; N=4) (Inger & Marx 1965: 136).

Coloration: dark brown above, each dorsal scale with a fine dark network; some dorsal scales with dark central spots; spots not forming dark lines; scales of first row with light centers and dark edges forming white stripe running length of body; top of head brown with dark spots, dark pigment ending on supralabials; usually lower half of supralabials yellow, with or without dark sutures; underside of head yellow usually with dark spots on sutures; ventrals yellow, dark brown at lateral edges, central portion immaculate or with a median row of small dark spots; underside of tail yellow, with or without median dark line (Inger & Marx 1965: 136).

Comparisons. Calamaria palavanensis and virgulata are the only species of this genus known from Palawan. These two species differ in subcaudal counts where they occur together, as south of Bolicao, Palawan. At that locality palavanensis has higher subcaudal counts than virgulata (females 16-20 compared to 8-14) . The eye of palavanensis is much larger than that of virgulata. The tail of palavanensis tapers to a point, that of virgulata is blunt.
Calamaria palavanensis is most similar to everetti, grabowskyi, and suluensis. These four forms have in common similar dorsal coloration, a continuous white stripe on the first scale row, a large eye, and a moderately long tail.
Calamaria palavanensis differs from grabowskyi in having the mental separated from the anterior chin shields, in lacking dark cross bands on the ventrals, and in having the frontal shorter than the parietal.
Calamaria palavanensis differs from suluensis in having the mental separated from the anterior chin shields and higher ventral counts.
Calamaria palavanensis differs from everetti in having a thicker and shorter tail, the reduction to four dorsal rows closer to the tip of the tail, and higher ventral counts.
The Palawan form could have been considered a subspecies of any of the three Bornean species with which we have just compared it. As these three Bornean forms are sympatric with each other they cannot be considered conspecific. The exact relationship of the Palawan form with these three cannot be determined with the material at hand. Our designation of palavanensis as a full species must be considered tentative.
This form is also similar to Bornean modesta, which have a white stripe on the first scale row. Calamaria modesta has a shorter snout and a slightly smaller eye than palavanensis. The combined length of the supraocular and prefrontal is equal to, or slightly greater than, the length of the parietal in palavanensis whereas this relationship is reversed in modesta (Table 37). The diameter of the eye in palavanensis is longer than the ventral border of the prefrontal; in modesta the diameter of the eye is sometimes equal to but usually shorter than the ventral border of the prefrontal.
Calamaria modesta shows sexual dimorphism in ventral counts (Table 39), whereas palavanensis does not. Only in palavanensis and everetti have we failed to find sexual dimorphism in ventral counts (Inger & Marx 1965: 136). 
EtymologyNamed after the type locality. 
  • Grismer, L. L., H. Kaiser & N. S. Yaakob 2004. A new species of Reed Snake of the genus Calamaria H. Boie, 1827, from Pulau Tioman, Pahang, West Malaysia. Hamadryad 28 (1&2): 1-6 - get paper here
  • Inger, R. F. & H. MARX 1965. The systematics and evolution of the oriental colubrid snakes of the genus Calamaria. Fieldiana: Zoology 49: 1-304. - get paper here
  • Wallach, Van; Kenneth L. Williams , Jeff Boundy 2014. Snakes of the World: A Catalogue of Living and Extinct Species. [type catalogue] Taylor and Francis, CRC Press, 1237 pp.
  • Weinell, J. L., Leviton, A. E., & Brown, R. M. 2021. A new species of reed snake, genus Calamaria (Colubridae: Calamariinae), from Mindoro Island, Philippines. Philippine Journal of Systematic Biology, DOI 10.26757/pjsb2020b14006 - get paper here
  • Weinell, Jeffrey L.; Errol Hooper, Alan E. Leviton, Rafe M. Brown 2019. Illustrated Key to the Snakes of the Philippines. Proc. Cal. Acad. Sci. (4) 66 (1): 1-49 - get paper here
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