Oligodon barroni ( Smith, 1916 )

David, P., Vogel, G. & van Rooijen, J., 2008, A revision of the Oligodon taeniatus (Günther, 1861) group (Squamata: Colubridae), with the description of three new species from the Indochinese Region, Zootaxa 1965, pp. 1-49 : 36-40

Oligodon barroni ( Smith, 1916)

( Figs. 25–28)

Simotes barroni Smith, 1916: 46 . – Type locality. “Hup Bon, E. of Sriracha, S. E. Siam”, now Hup Bon , east of Si Racha, Chon Buri Province, southeastern Thailand. – Syntypes. Three specimens according to the original description: BMNH 1946.1 .3.21 (adult male; ex BMNH 1917.5.14.16), BMNH 1946.1 .3.22 (adult male; ex BMNH 1917.5.14.16), and BMNH 1946.1 .3.26 (adult male; ex BMNH 1917.5.14.16). Collected by Mr. P. A. R. Barron.

Holarchus taeniatus caudaensis Bourret, 1934: 173 . – Type locality. “Cauda” now Cau Da, near Nha Trang, Khán Hoa Province, Vietnam. – Syntypes. Three specimens, K. 333 and M. 152 (both juvenile; R. Bourret’s collection number; neither traced, probably in Hanoi), and MNHN 1938.0134 (juvenile, probably male); Collected by Mr Krempf, deposited (MNHN) by René Bourret. – Synonymized with Oligodon barroni by Smith (1943: 210).

Material (20 specimens). – THAILAND. Chanthaburi Province . BMNH 1969.1784 (female), “Khao Sebab, S.E. Siam”, now Khao Sabap , near Chanthaburi. Chon Buri Province. BMNH 1946.1 .1.20 , BMNH 1946.1 .1.93 (both ex BMNH 1921.4.1.16; 2 males) , BMNH 1946.1.3.21–22 (both ex BMNH 1917.5.14.5; 2 males) , BMNH 1946.1 .3.26 (ex BMNH 1917.5.14.16) (1 male), Hup Bon, E. of Sriracha, S. E. Siam ”, now Hup Bon, east of Si Racha ; BMNH 1946.1 .3.37 (ex BMNH 1921.4.1.18; female) , BMNH 1969.1780 , BMNH 1969.1782 – 1783 , BMNH 1969.1786 (4 females) , BMNH 1969.1781 (male), Sriracha, now Si Racha ; BMNH 1969.1779 (male), “Koh Lam, S.E. Siam”, now Ko Lam . Saraburi Province. BMNH 1946.1 .3.36 (ex BMNH 1921.4.1.17; female), “Muak Lekquo, Dong Rek Range, E. Siam ”, now Muak Lek ; BMNH 1969.1778 , BMNH 1969.1785 (2 males), “Pak Jong”, now Pak Chong . – LAOS. Champasak Province. MNHN 2003.3329 (male), Xepian NBCA ; MNHN 2003.3330 (female), Huay Saoe (Saoe Stream), near Taong . – VIETNAM. Gia Lai Province. MNHN 1973.0143 (female), “Choreo, prov. de Phu-Bôn”, now Cheo Reo (13°25’N 108°30’E) . Khanh Hoa Province. MNHN 1938.0134 (juvenile), “Cauda: près de Nha Trang, S. Annam”, now Càu Dá, near Nha Trang ; MNHN 1958.0458 (male), Nha Trang .

Taxonomic comments. – Two other specimens from the same locality are identified as syntypes in the catalogue of the BMNH, but the original description of Simotes barroni was based only on the three specimens listed above. We have no hesitation about the synonymy of Holarchus taeniatus caudaensis Bourret, 1934 with Oligodon barroni .

Diagnosis. – A species of the genus Oligodon , characterized by: (1) a large size for the group, up to about 400 mm in total length; (2) deeply forked hemipenes, not spinose but fitted with two large papillae; (3) 17 dorsal scale rows at midbody, 15 before vent; (4) 10–13 maxillary teeth, the last two strongly enlarged; (5) head scalation complete, never including a presubocular (see below); (6) 7 (rarely 8) supralabials; (7) anal plate single; (8) the presence of 10–14 dark brown or black blotches on the upper surface of body + 2–3 on the tail; (9) five major markings on upper head surface: one anterior transverse blotch across the snout; one longitudinal, frontal marking; one pair of paramedian central, oblique streaks, directed posteriorly downwards; and one arrow-shaped nuchal blotch; and (10) branches of the oblique central streak not reaching the ventral scales.

Oligodon barroni differs from all other species of the O. taeniatus -group in the combination of (1) 17 scale rows at midbody, (2) the presence of large, dark hexagonal or butterfly-like dorsal blotches on the body and the tail, (3) the absence of a vertebral stripe, and (4) a low number of maxillary teeth. With its dorsal blotches, this species cannot be really confused with any other species of O. taeniatus -group.

Description and variation (based on Smith [1943] and Saint Girons [1972], and 20 examined specimens). – Morphology. Body rather elongated but not especially thin; head short, thick, barely distinct from the poorly defined neck; snout projecting forward of the lower jaw, long, amounting to 27.1–33.6 % (x = 30.4 %, s = 4.6) of HL, or 1.7–1.8 (x = 1.8, s = 0.1) times as long as diameter of eye; eye rather small, with a round pupil; tail thick and tapering. The maximal total length known is 401 mm (SVL 346 mm, TaL 55 mm) for a female (MNHN 1973.0143). The largest examined male is 367 mm long (SVL 298 mm, TaL 69 mm; BMNH 1946.1.3.21). Ratio TaL/TL: 0.137 –0.189, with a strong sexual dimorphism (see below).

Dentition. 10–13 maxillary teeth (x = 11.4, s = 0.9), the last two being strongly enlarged and blade-like.

Body scalation. DSR: 17–17–15, without exception; scales small, ovoid, all smooth.

VEN: 136–160 (plus 1–2 preventrals), slightly angulate; SC: 28–48, paired (with a sexual dimorphism); anal plate entire.

Head scalation. Rostral thick, curved onto the upper snout surface, well visible from above, separating internasals by about one half of their length; nasals subrectangular, about 1.6–1.8 times as long as high, vertically divided, with the posterior part distinctly smaller; nostril crescentic, piercing middle of nasal just forward of the division; internasals subrectangular, in broad contact, much shorter than prefrontals; prefrontals subrectangular, much wider than long; frontal hexagonal, ogive-like pointing backwards, 1.10–1.25 times as long as wide (x = 1.20, s = 0.05); an undivided supraocular on each side, much longer than wide, as wide as prefrontals; 2 very large, subtriangular parietals, much longer than the frontal, in broad contact; 1/1 small loreal, about 1.1–1.2 times as long as high, in broad contact with nasal; 7/7 (in 17/ 20 specimens), 7/8 (in 2/20) or 8/8 (in only 1/20) supralabials, 1 st SL small, 2 nd (in 14/40 occurrences) or 2 nd and 3 rd (in 26/40) in contact with loreal, 4 th and 5 th entering orbit in all specimens, 5 th and 6 th largest; 1/1 preocular, high and narrow in all examined specimens; no presubocular; 2/2 small postoculars in all examined specimens; 1/1 elongated anterior temporals, 2/2 posterior temporals; 7/8 (in 1/ 20 specimens), 8/8 (in 8/20), 8/9 (in 1/20) or 9/9 (in 10/20) infralabials, first pair in contact, IL 1–4 in contact with anterior chin shields, 4 th IL the largest.

Colouration and pattern in alcohol and in life. The upper surface is brownish-grey or greyish-tan, with many dorsal scales finely edged with dark brown, more distinctly in their lower part, producing a strongly dotted pattern; two parallel series of irregular white elongated dots or streaks extend from the nape mark up to the tip of the tail along the vertebral row; these white streaks result from the yellow interstitial skin and the white (yellow in life) edges of some scales or the two rows adjacent to the vertebral row but do not form a defined vertebral stripe; on the back, between 10 and 14 large, dark brown or blackish-brown blotches (dark purplishbrown in life), more or less hexagonal or “butterfly-like”; these blotches are 2 to 3 scales long and 4 or 5 scales wide; some are nearly broken at the level of the vertebral stripe (according to Campden-Main [1970], specimens from southern Vietnam have fainter dorsal blotches); 2 or 3 oblique fasciatures on the sides of the body between each dorsal blotch; a series of lateral dark brown spots on dorsal scale rows 3–4, forming an irregular lateral dark brown stripe on each side. The tail is as the upper body surface, with the vertebral stripe paler than the background colour and 3 vertebral blotches similar to but smaller than those of the body; the first blotch is located at the level of subcaudals 1–5, its anterior tip reaching the level of the anal plate; last one about 5 SC before the tip; some lateral dark brown dots but no conspicuous lateral stripe.

The head is brownish-grey or greyish-brown, darker than body on its upper surface; supralabials light brown (cream in life), more or less finely variegated with dark brown; 5 major markings dorsally, as follows: a broad transverse dark brown marking on the snout, just in front of eyes, extends downwards obliquely backwards across the eye down to SL 4–5; a short, narrow, arrow or water drop shaped, longitudinal streak on the frontal; a pair of paramedian large, oblique dark brown or blackish-brown marking on frontal (not in contact with each other), anterior part of parietals and posterior temporals, reaching side of neck behind the corner of the mouth, then, downwards, do not reach the corresponding ventral (in close contact on one side in two specimens from Laos); lastly, a conspicuous, dark brown, ogive- or heart-shaped, nuchal blotch, pointing forward. Infralabials, chin and throat uniformly creamish-yellow, sometimes infralabials finely edged with greyish-brown.

The venter is creamish-yellow (pink or red in life), dotted with an irregular black subrectangular blotch near both tips of ventrals; some ventrals have only one blotch, especially in the anterior third of body where blotches are smaller; lower tail surface as venter, with subrectangular blotches only on the anterior half of the tail.

Hemipenis (in situ). – The hemipenis is similar to that of Oligodon taeniatus but slightly shorter; it is forked opposite the 5 th SC and reaches SC 10–12. On its proximal part it is covered with calyces; the distal parts are smooth. The very long papillae, all smooth, are as in O. taeniatus .

Sexual dimorphism. – Clearly present in the two following characters: (1) difference in the ratio TaL/TL: males: 0.170 –0.189 (x = 0.180, s = 0.007); females: 0.137 –0.150 (x = 0.143, s = 0.006); (2) difference in the number of subcaudals: males: 36–48 (x = 40.8, s = 3.4); females: 28–35 (x = 32.6, s = 2.4). The difference in the number of ventrals is not well defined: males: 136–147 (x = 143.1, s = 3.3); females: 141–153 (x = 147.3, s = 4.8; values according to examined specimens; up to 160 VEN according to Smith, 1943).

Distribution. – Thailand. Centre and Southeast of the country, in the provinces of Bangkok, Chanthaburi (Khao Sabap, near Chanthaburi), Chon Buri (Sriracha, Koh Lam Island), Rayong (Muang), and Saraburi (Muak Lek, Pak Chong) ( Taylor, 1965; Nabhitabhata et al., 2004; examined material). – Cambodia. Cardamom Mountains ( Daltry & Dany, 2000); no other precise locality ( Saint Girons, 1972). – Laos. South: Champasak Province (Xepian; Saoe, near Taong) ( Teynié et al., 2004). – Vietnam. Only known from the Centre and South: provinces of Bình Duong (ex Sông Bé) (Lai Khê), Gia Lai (Cheo Reo), and Khanh Hoa (Càu Dá, near Nha Trang) ( Campden-Main, 1970; Nguyên et al., 2005; examined material).

A specimen from Saraburi Province in Thailand mentionned by Taylor (1965: 776) is here referred to Oligodon pseudotaeniatus spec. nov. Nguyên et al. (2005) cited localities from the Vietnamese provinces of Cao Bang (Nguyên Bình) and Hai Duong (Chí Linh) respectively. These provinces being in the extreme North of the country, we suspect misidentifications.

Biology. – Nothing is known but it presumed to be similar to O. mouhoti .