Oligodon amabilis (Lee & Yushchenko & Pal & Vogel & Poyarkov & Bauer, 2025)

Oligodon amabilis comb. nov. ( Günther, 1868)

Figs. 11–14 View FIGURE 11 View FIGURE 12 View FIGURE 13 View FIGURE 14

Simotes amabilis Günther , A.C. L.G. (1868: 416, pl. 17A). In: Sixth account of new species of snakes in the collection of the British Museum. Annals and Magazine of Natural History , including Zoology, Botany, and Geology. Series 4, 1, 413–429 + pls. 17–19. Holotype. NHMUK 1948.1 About NHMUK .1.8 [Type locality: “ Arakan Hills” (= Rakhine Yoma, Rakhine State, Myanmar)]. ( Fig. 11 View FIGURE 11 ).

Simotes amabilis , — Theobald 1868a: 41; Theobald 1868b: 47; Boulenger 1890: 312; Boulenger 1894: 220; Wall 1914: 758; Wall 1923a: 326; Smith 1943: 211; Iskandar & Colijn 2001: 70; Schleich & Kästle 2002: 892; Green 2010: 86.

Simotes albocinctus View in CoL ( nec Coronella albocincta Cantor, 1839 View in CoL ).— Boulenger 1890: 312 (in part).

Oligodon albocinctus View in CoL (in part)— Wall 1923a: 326; Smith 1943: 211; Mertens 1956: pl. 8 ( Fig. 13 View FIGURE 13 ) (reproduces pl. 17 from Günther 1868); Iskandar & Colijn 2001: 70; Schleich & Kästle 2002: 892; Green 2010: 86.

Simotes albocinctus View in CoL var. B.— Boulenger 1894: 220.

Oligodon albocinctus View in CoL clade 2.— Lee et al. 2024: Fig. 2 View FIGURE 2 .

Holotype. NHMUK 1946.1 About NHMUK .1.8 (immature male) ( Fig. 11 View FIGURE 11 ) from “ Arakan Hills” [ Rakhine Yoma, Rakhine State, Myanmar] collected by William Theobald prior to 16 January 1868. The exact whereabouts of the holotype are unknown, though Theobald was known to have obtained material throughout the southern end of the Rakhine Yoma. We specify the coordinates of the type locality near present-day Thandwe, Thandwe District ( 18.76779ºN, 94.60149ºE) as it is close to adjacent records of referred specimens, and in the center of the Rakhine Yoma. GoogleMaps

Referred specimens ( N = 6). Myanmar. Rakhine State. CAS 216636 About CAS (JBS-7351; adult female) from vicinity of Kanthaya Beach, Gwa Township, Thandwe District ( 17.720720ºN, 94.534690ºE) collected 26 November 2000 by J.B. Slowinski and H. Win GoogleMaps . CAS 221933 About CAS (JBS-8943; adult male) from Rakhine Yoma Elephant Wildlife Sanctuary, Gwa Township, Thandwe District ( 17.615972ºN, 94.588806ºE) collected 2 June 2001 by H. Win GoogleMaps , T. Thin, K.S. Lwin and A.K. Shein . CAS 239961 About CAS (JBS-21445; adult male) Kantawpyin Village, Yambye Township, Kyaukpyu District ( 19.021917ºN, 93.812861ºE) collected 5 November 2007 by A.K. Shein, S.L. Oo, and Y.M. Win GoogleMaps . CAS 239858 About CAS (JBS-21192; adult male) from Chin Minbyin village, Kyaukpyu Township, Kyaukpyu District ( 19.185583ºN, 93.733694ºE) collected 22 October 2007 by A.K. Shein, S.L. Oo, and K.S. Lwin GoogleMaps . CAS 240016 About CAS (JBS-21560; adult male) from Aung Si Kone Village, Yambye Township, Kyaukpyu District ( 19.056750ºN, 93.838944ºE) collected 9 November 2007 by S.L Oo, A.K. Shein, and Y.M. Win GoogleMaps . CAS 240055 About CAS (JBS-21642; adult female) from Pyonepyae Village, Kyaukpyu Township, Kyaukpyu District ( 19.198623ºN, 93.769884ºE; these coordinates are based on the approximate location of Pyonepyae Village on Google Earth , which differs from the lat/long values on-file in the CAS database) collected 13 November 2007 by A.K. Shein, S.L. Oo, and Y.M. Win GoogleMaps .

Diagnosis. A moderately sized Oligodon with a relatively long tail. Maximum total length approximately 738 mm, relative tail length 0.153 –0.219 ( 0.187 –0.219 in males, 0.153 –0.171 in females). Dorsal scales in 19–19–15 rows, all smooth. Ventrals 170–186 ( 170–179 in males, 180–186 in females) without distinct keeling; cloacal plate undivided; subcaudals 48–66 ( 56–66 in males, 48–49 in females), paired; total body scales 228–244; subcaudal ratio 0.203 –0.273 ( 0.240 –0.273 in males, 0.203 –0.213 in females). Maxillary teeth 14–16. Loreal present, preocular 1/1, presubocular absent, postoculars 2/2, temporals 1+2. Supralabials 7, third and fourth scale in contact with eye. Infralabials 9, fourth or fifth scale contacting with anterior pair of chin shields.

Typical morph red or reddish brown dorsally, 22–41 white or yellow crossbands on body, 8–15 on tail (total = 31–56 bands), all edged with black forming a tricolored pattern. Second morph brown with dark irregular crossbars (43 body blotches and 9 tail blotches in single exemplar). Interspace between each band/blotch 4–6 vertebral dorsal scales long at midbody. First band/blotch begins between ventral scales 6–8. Ventral surface plain white or cream with small dark brown or black rectangular blotches on lateral margins of ventral scales. Posteriorly, ventral surface usually darkening from cream to dark gray until cloacal region. Underside of tail plain, occasional rectangular spots present anteriorly. Hemipenis bilobed, sulcus spermaticus simple, proximal third calyculate, remaining two-thirds and apices of lobes broad, subtriangular and covered with rows of horizontal flounces.

Redescription of holotype. Immature male in good condition, midventral incision from anterior one third of body to cloaca, internally eviscerated ( Fig. 11 View FIGURE 11 ). SVL 203 mm, TailL 46 mm, TotalL 249 mm, HeadL 11.9 mm, HeadW 7.4 mm, SnL 3.7 mm, SnW 2.9 mm, EyeD 2.1 mm, FrontalL 3.5 mm, FrontalW 2.5 mm, InterorbD 4.5 mm. TailLR 0.185, HeadW/L 0.62, SnL/HL 0.31, EyeD/SnL 0.57, EyeD/HeadL 0.18, FrontalL/W 1.41. Body elongate, subcylindrical. Head ovate, distinct from neck. Snout round, tapered in dorsal profile, slightly depressed in lateral profile, upper jaw projects further than lower jaw, canthus rostralis absent. Eyes moderate, pupil round. Tail broad at base, gradually tapering in diameter along distal third to sharp acuminate tip.

Dorsal scales in 19–19–15 rows, all smooth. Dorsal scale reduction from 19 to 17 scales at 101 st ventral, 17 to 15 scales at 141 st ventral (0.57 and 0.79 of ventrals, respectively), both on left side of body. Ventral scales 177, no distinct lateral keeling, preventrals 1. Cloacal plate undivided. Subcaudals 62, paired. Total body scales 242, subcaudal ratio 0.265. Data on dentition from F. W. Wagner as follows: maxillary teeth 15, palatine teeth 9, pterygoid teeth 24. Hemipenis unknown.

Rostral triangular, height and width equal, posterior suture bordering internasals form a broad gull-wing shaped obtuse angle (~119º). Nasal subpentagonal, 1.6 times longer than high, anterior suture 2.1 times higher than posterior suture. Small vertical suture divides nasal above and below nostril. Each nasal in contact with rostral, internasal, prefrontal, loreal, and first to second supralabial. Internasals paired, trapezoidal in dorsal profile, 2.4 times wider than median suture, entire scale 1.6 times wider than long, anterior and posterior sutures weakly concave. Each internasal in contact with prefrontal, rostral, and nasal. Prefrontals paired, subhexagonal, each scale 1.1 times wider than long, 1.7 times wider than median suture. Median suture of prefrontals 2.0 times longer than median suture of internasals. Each prefrontal in contact with internasal, nasal, loreal, preocular, supraocular, and frontal. Supraoculars subrectangular, 1.9 times longer than width of posterior suture, posterior suture 1.4 times wider than anterior suture, in contact with preocular, prefrontal, frontal, uppermost postocular, and parietal. Frontal pentagonal, shield shaped, 1.2 times longer than median parietal suture. Anterior frontal suture straight, positioned in front of eyes. Posterior vertex of frontal bordering parietals forming a very weak obtuse angle (~92º). Parietals paired, subpentagonal, median suture 1.1 times longer than wide, entire scale 1.5 times longer than wide and 1.2 times longer than frontal. Anterior suture bordering frontal and supraoculars straight, angled obtusely (~123º), its ray oriented laterally. Posterior suture of each parietal slightly bent. Seven scales (excluding postoculars) surround parietals. Loreal 1/1, square, height and width equal, posterior suture 1.5 times higher than anterior suture, in contact with nasal, preocular, prefrontal and third supralabial. Preocular 1/1, rectangular, higher than long. Presubocular scale absent. Postoculars 2/2, subrectangular, uppermost scale slightly larger than lowermost. Temporals 1+2, uppermost posterior temporal longer than lowermost. Supralabials 7/7, first two scales in contact with nasal, second in contact with loreal, second and third in contact with preocular, third and fourth in contact with eye, fourth and fifth in contact with lower postocular, fifth and sixth in contact with anterior temporal, and sixth and seventh in contact with lowermost posterior temporal. Sixth supralabial largest, first supralabial smallest. Infralabials 9/9, first five scales in contact with anterior chin shields, sixth scale contacting posterior chin shields. Sixth infralabial largest, second scale smallest. First pair of infralabials contact medially. Mental scale triangular, wider than long. Anterior chin shields rectangular, longer than wide. Posterior chin shields smaller than anterior pair, each shield in contact at midline for two-thirds of their length, suture bordering gulars convex. Poorly defined mental groove present between first infralabials and both pairs of chin shields.

After 157 years in preservative, dorsal surface reddish brown ( Fig. 11A View FIGURE 11 ). Dorsal pattern tricolored, 41 light tan bands with narrow black edges on body, 15 bands on tail. Body bands extend across almost all the dorsal surface except for outermost 2–3 dorsal scale rows, which are plain. Insertion of first white crossband begins above level of the sixth ventral scale. Width of light bands 1.0 dorsal scales long, black edges one-half dorsal scales long. Interspace between each band four vertebral dorsal scales at midbody. An indistinct series of dark paravertebral and lateral stripes present from nape to end of tail. Paravertebral stripes each brown, one dorsal scale long and engulf a single light middorsal line. Lateral stripes also brown, each one dorsal scale wide, present at midbody on the fourth outermost dorsal scale row and edge of the third dorsal scale row. Ventrolateral edge of tail along outermost dorsocaudal scale rows brown, bolder than remaining tail. Dorsal surface of head tan. Snout light brown, plain. Dorsal ornamentation on head consists of one ocular bar, one temporal streak on each side, and an incomplete nuchal chevron, all markings reddish brown with their outlines dark brown ( Fig. 11C View FIGURE 11 ). Ocular bar begins at supralabials 4– 5, continuing across each side of head through eye before meeting across prefrontals, anterior edges of supraoculars and anterior edge of frontal. Temporal bar incomplete, starting at anterolateral edge of each parietal, continuing through posterior temporals before terminating at flanks near first dorsal scale row. Nuchal chevron a lanceolate projection extending from nape between the median suture of each parietal and terminating at the posterior vertex of frontal scale. A single irregular spot present within the median portion of frontal and anterior corner of right parietal. Eye blue, pupil tan. Underside of head tan, occasional dark pigmentation within scale sutures ( Fig. 11B View FIGURE 11 ). Ventral surface same as head, edges of ventral scales with small brown subtriangular spots, sparse anteriorly, present every other ventral scale at midbody and posteriorly until the cloaca. Lateral margins of every ventral scale near flanks reddish brown. Underside of tail tan, immaculate.

General description and variation. Adult SVL 413–603 mm (excluding holotype, a juvenile), TailL 98–135 mm, TotalL 524–738 mm. The largest specimen is an adult male (CAS 221933) measuring 603 mm SVL and 135 mm TailL. Largest female (CAS 216636) 552 mm SVL and 100 mm TailL. Other head measurements and ratios noted as follows: HeadL 11.9–18.9 mm, HeadW 7.4–13.6 mm, SnL 3.7–6.3 mm, SnW 2.9–4.3 mm, EyeD 2.1–3.0 mm, FrontalL 3.5–5.6 mm, FrontalW 2.5–4.4 mm, InterorbD 4.5–6.6 mm. TailLR 0.153 –0.219 ( x̄ = 0.189 ± 0.023, N = 7), in males 0.187 –0.219 ( x̄ = 0.199 ± 0.016, N = 5), in females 0.153 –0.171 ( x̄ = 0.161 ± 0.012; N = 2). HeadW/ L 0.60–0.85, SnL/HL 0.30–0.40, EyeD/SnL 0.46–0.57, EyeD/HeadL 0.14–0.20, FrontalL/W 1.15–1.41.

Dorsal scales in 19–19–15 rows, all smooth. Reduction from row 19 to 17 at ventral scale 95–112 (0.56–0.61 of ventrals), 17 to 15 at ventral scale 132–170 (0.78–0.91 of ventrals). Ventral scales 170–186 ( x̄ = 177.6 ± 4.9; N = 7), in males 170–179 ( x̄ = 175.4 ± 3.4; N = 5), in females 180–186 ( x̄ = 183.0 ± 4.2; N = 2), no distinct keeling. Subcaudal scales 48–66 ( x̄ = 57.7 ± 7.3; N = 7), in males 56–66 ( x̄ = 61.4 ± 6.9; N = 5), in females 48–49 ( x̄ = 48.5 ± 0.5; N = 2), all paired. Cloacal plate undivided. Total body scales 228–244 ( x̄ = 236.3 ± 6.4; N = 7). Subcaudal ratio 0.203 –0.273 ( x̄ = 0.244 ± 0.026; N = 7), in males 0.240 –0.273 ( x̄ = 0.258 ± 0.013; N = 5), in females 0.203 –0.213 ( x̄ = 0.208 ± 0.006). Sexual dimorphism recorded for ventral scale counts, relative tail length and subcaudal ratio values, but not for the number of subcaudals.

Maxillary teeth 14–16 ( N = 7), anteriormost teeth small, gradually increasing in size posteriorly. Posteriormost three or four maxillary teeth enlarged, blade-like, laterally compressed. In CT-scanned specimen CAS 240055, palatine teeth 12/13, pterygoid teeth 22/23, dentary teeth 18/18.

Rostral height/width equal, posterior suture bordering internasals obtuse angled, forming a deep V or gull-wing shape in dorsal profile (96–129º). Nasal subpentagonal, divided, longer than high, anterior suture higher than posterior suture. Each nasal in contact with rostral, internasal, prefrontal, loreal, and first to second supralabial. Internasals paired, trapezoidal, entire scale wider than long, wider than length of median suture. Anterior and posterior internasal sutures straightened ( CAS 239961 About CAS , CAS 240016 About CAS , CAS 240055 About CAS ) or weakly concave ( holotype + remaining specimens). Each internasal contacts prefrontal, rostral, and nasal. Prefrontals paired, subhexagonal, entire scale wider than long, wider than length of median suture. Each prefrontal contacting internasal, nasal, loreal, preocular, supraocular and frontal. Supraoculars subrectangular, longer than wide, posterior suture wider than anterior suture. Each supraocular in contact with preocular, prefrontal, frontal, uppermost postocular, and parietal. Frontal pentagonal, shield shaped, longer than median parietal suture. Anterior frontal suture positioned in front of eye sockets. Posterior vertex of frontal bordering parietals acute to weakly obtuse angled (81–96º). Parietals paired, subpentagonal, entire scale longer than wide and longer than frontal. Median parietal suture longer than parietal scale width. Anterior parietal suture bordering frontal and supraoculars straight, angled obtusely (119–136º), ray oriented laterally. Posterior suture of each parietal slightly bent. Seven scales (excluding postoculars) surround parietals in holotype and two additional specimens ( CAS 221933 About CAS , CAS 240016 About CAS ), eight scales in three specimens ( CAS 216636 About CAS , CAS 239858 About CAS , CAS 240055 About CAS ), nine in a single specimen ( CAS 239961 About CAS ). Loreal 1/1, square, height and width equal, posterior suture higher than anterior suture. Loreal contacts nasal, preocular, prefrontal and third supralabial. Preocular 1/1, rectangular, higher than long. Presubocular scale absent. Postoculars 2/2, subrectangular, uppermost scale slightly larger than lowermost. Temporals 1+2, uppermost posterior temporal longer than lowermost. Supralabials 7/7, first two scales in contact with nasal, second in contact with loreal, second and third in contact with preocular, third and fourth in contact with eye, fourth and fifth in contact with lower postocular, fifth and sixth in contact with anterior temporal, and sixth and seventh in contact with lowermost posterior temporal. Sixth supralabial largest, first supralabial smallest. Infralabials 9/9, first five in contact with anterior chin shields in holotype and one specimen ( CAS 239858 About CAS ), 4/4 infralabials contact anterior chin shields in remaining material. Sixth infralabial contacting posterior chin shields. Sixth infralabial largest, second infralabial smallest. First pair of infralabials contact medially. Mental scale triangular, wider than long. Anterior chin shields rectangular, longer than wide. Posterior chin shields smaller than anterior, each shield in contact at midline for one-half to two-thirds of their length, suture bordering gulars concave. Poorly defined mental groove present between first infralabials and both pairs of chin shields .

In preservative, typical color morphotype reddish-brown dorsally with a series of white or tan bands, each surrounded by narrow black edges ( Fig. 12 View FIGURE 12 ). The ground color in one specimen (CAS 239961) is plain brown, and the body and tail bands in another are light pink (i.e., CAS 240016). The black edges of each band may expand laterally along the flanks (CAS 221933). Number of bands or crossbars in all specimens (including CAS 239858) range from 22–43 on body ( x̄ = 34.0 ± 8.3, N = 7) to 8–15 on tail ( x̄ = 10.4 ± 2.7, N = 7), total bands 31–55 ( x̄ = 44.4 ± 9.4, N = 7). Body bands extend across dorsal surface until outermost 1–3 dorsal scale rows. Insertion of first white crossband begins above ventral scale 6–9 ( x̄ = 7.0 ± 0.82; N = 7). Width of light bands 1.0 dorsal scales long, black edges 0.5–1.0 dorsal scales. Interspace between each band 4–6 vertebral dorsal scales at midbody ( x̄ = 4.6 ± 0.78; N = 7). An indistinct series of paravertebral and lateral stripes normally present from nape to tail terminus but barely visible or essentially absent in two adults (CAS 221933, CAS 240055). Paravertebral stripes one dorsal scale wide, each engulfing a single narrow middorsal line ( Fig. 12C View FIGURE 12 ). Lateral stripe one or two dorsal scales wide, present on third and/or fourth outermost dorsal scale rows. Ventrolateral edge of tail along outermost dorsocaudal scale rows and margins of each subcaudal brown, bolder than remaining portion of tail. Dorsal surface of head tan or light brown, darker towards snout. Head markings consist of one ocular bar, a paired temporal streak, and one nuchal chevron, all reddish brown with dark brown edges. Ocular bar begins at supralabial 4–5 and extends through eye before covering prefrontals, anterior edges of supraoculars and anterior edge of frontal. In four specimens the ocular bar may enter the posterior edge of the internasals (CAS 221933, CAS 239961, CAS 240016, CAS 240055). Temporal bars begin at anterolateral edge of parietal, continue through posterior temporals before terminating ventrolaterally at first dorsal scale row. Nuchal chevron lanceolate, extending from nape through the median suture of parietal and frontal. Median frontal spot disconnected from chevron in holotype and two other specimens (CAS 221933, CAS 240055). Underside of head and body tan, edges of ventral scales with small brown subtriangular spots, sparse anteriorly, present every other ventral scale at midbody and posteriorly until the cloaca. Midbody and posterior portions of ventral surface dark brown in two specimens (CAS 239961, CAS 239858). Lateral margins of ventral scale near flanks reddish brown. Underside of tail tan, brown mottling present anteriorly in two specimens (CAS 216693, CAS 239961, CAS 239858), sparser in CAS 216693 ( Fig. 12 View FIGURE 12 ).

A single male ( CAS 239858 About CAS ) from Kyaukpyu Township exhibits a blotched morphotype separate from other specimens described above ( Fig. 13 View FIGURE 13 ). The dorsal surface is light brown with small black spots on most scale edges. A narrow, indistinct series of and dark brown crossbars present (43 on body, 9 on tail), less than one dorsal scale in width. Each crossbar incomplete, consisting of alternating rows of small spots or reticulations connected along dorsal scale edges. Paravertebral and lateral stripes dark brown, similar in size and arrangement as holotype. Dorsal head markings brown with black edges. Nuchal chevron dark brown, separate from dorsal ground color forming a subtriangular arrow marking, each terminating posteriorly along nape. Color of ventral surface resembles holotype and other referred material ( Fig 13B View FIGURE 13 ) .

Color in life based on digitized slides of a single specimen ( CAS 216636 About CAS ) from Gwa Township , Rakhine State, Myanmar taken prior to euthanasia ( Fig. 14 View FIGURE 14 ). Dorsal surface light red, all body and tail bands whitish yellow with black edges. Paravertebral and lateral stripes reddish brown, barely visible dorsally. Ventrolateral line along tail plain brown. Head light brown, markings tan with black edges. Ventral underside tan .

Description of hemipenis. Hemipenis bilobed upon full eversion, noncapitate and calyculate. Partially everted hemipenis unilobed, proximal one quarter or one third of organ with small irregular rows of calyces. Distal three quarters or two thirds of organ with long horizontal flounces across base, asulcate and sulcate profiles of lobes, apical portion of organ nude. Hemipenial lobes broad, more than two thirds of hemipenial length, longer than wide, terminating as bulbous subtriangular awns. Sulcus spermaticus simple, starting at organ base before extending medially until terminating at bifurcation point between lobes. Sulcus channel indistinct.

Comparisons. Oligodon amabilis comb. nov. is compared with all Oligodon inhabiting Myanmar and adjacent regions. The presence of 19–19–15 dorsal scale rows in O. amabilis comb. nov. immediately distinguishes this species from all members of the Oligodon ornatus Group ( Oligodon catenatus ( Blyth, 1854) and Oligodon hamptoni Boulenger, 1918 ) and Oligodon theobaldi Group ( Oligodon cruentatus ( Theobald, 1868a), Oligodon dorsalis , Oligodon erythrogaster Boulenger, 1907 , Oligodon mcdougalli , Oligodon planiceps ( Boulenger, 1888) , Oligodon theobaldi ( Günther, 1868) and Oligodon torquatus ( Boulenger, 1888)) native to Myanmar and surrounding countries, all of which have a maximum of 13–17 dorsal scale rows. The number of dorsal scale rows also distinguishes O. amabilis comb. nov. from four Oligodon species native to China and northeast India ( Oligodon erythrorhachis Wall, 1910 , Oligodon melaneus Wall, 1909 , Oligodon melanozonatus Wall, 1922 , Oligodon zhangfujii Jiang, Wu, Huang, Ren, Gao, Lyu & Li, 2024 ), which have a maximum of 15–17 dorsal scale rows. Members of the Oligodon cyclurus –taeniatus Group native to Myanmar ( Oligodon cyclurus , Oligodon fasciolatus ) may resemble blotched O. amabilis comb. nov. in terms of coloration. O. amabilis comb. nov. is distinguished from both species by having seven supralabials ( versus usually eight or nine), one anterior temporal ( versus usually two anterior temporals) and no presubocular scale ( versus presubocular usually present). Within the Oligodon cinereus Group, the presence of 19–19–15 dorsal scale rows distinguish O. amabilis comb. nov. from all members of the O. cinereus species complex (all taxa in this group have 15–17 anterior and midbody scale rows) and from Oligodon splendidus (21 anterior and midbody scale rows).

Oligodon amabilis comb. nov. is most similar morphologically to Oligodon albocinctus (data after versus) but can be distinguished by usually having a higher number of body+tail bands (31–56 [ x̄ = 44.4 ± 9.4; N = 7] versus 20–33 [ x̄ = 27.5 ± 2.6; N = 101]) and a higher number of maxillary teeth (14–16 teeth [ N = 7] versus 8–12 teeth [ N = 27]). Statistically, Oligodon amabilis comb. nov. has a lower mean number of ventral scales (170–186 [ x̄ = 177.6 ± 4.9; N = 7] versus 174–207 [ x̄ = 189.9 ± 7.3; N = 134]) and a lower mean number of total body scales (228–244 [ x̄ = 236.3 ± 6.4; N = 7] versus 235–262 [ x̄ = 248.2 ±7.4; N = 124]). The ventral scale position of the first body band/blotch generally occurs earlier in O. amabilis comb. nov. than O. albocinctus (ventral scale 6–8 [ x̄ = 7.0 ± 0.8; N = 7] versus 7–19 [ x̄ = 10.2 ± 2.3; N = 95]), and the length in vertebral dorsal scales between bands at midbody is shorter than O. albocinctus (4–6 scales [ x̄ = 4.6 ± 0.78; N = 7] versus 6–9 [ x̄ = 7.2 ± 0.82; N = 95]) ( Table 3).

Distribution and natural history. Oligodon amabilis comb. nov. is endemic to southwestern Myanmar, where it is known only from Rakhine State along the western foothills of the Rakhine Yoma/ Arakan Hills ( Fig. 15 View FIGURE 15 ) (Appendix 6). All specimens with accurate geolocation data were collected at low, coastal elevations. The vertical distribution stretches from sea level to 74 meters asl. According to field notes from the CAS collection, most specimens were recorded from 1030–1940 hrs local time. Four specimens were collected during November, while one specimen (CAS 221933) was found in early June, and another (CAS 239858) was found in late October. No other data on its natural history are known.

Conservation status. The current distribution of Oligodon amabilis comb. nov. suggests it is endemic to southwestern Myanmar in Rakhine State. This region has seen substantial human conflict over the past few decades, with some studies noting an increase in deforestation and habitat destruction in areas where this species is known to occur ( Thiri Shwesin Aung 2021). At least one locality where O. amabilis has been found is encompassed by the Rakhine Yoma Elephant Wildlife Sanctuary, which may provide protection in the form of forest preservation. Still, other aspects that would allow a more detailed conservation assessment of this species are currently unavailable. Due to the small range of this species, and the threat of habitat loss, we recommend Oligodon amabilis comb. nov. should be listed as Data Deficient (DD) according to IUCN Red List criteria.