Platyceps josephi sp. nov. - Joseph's racer

Deepak, V., Narayanan, Surya, Mohapatra, Pratyush P., Dutta, Sushil K., Melvinselvan, Gnanaselvan, Khan, Ashaharraza, Mahlow, Kristin & Tillack, Frank, 2021, Revealing two centuries of confusion: new insights on nomenclature and systematic position of Argyrogena fasciolata (Shaw, 1802) (auctt.), with description of a new species from India (Reptilia: Squamata: Colubridae), Vertebrate Zoology 71, pp. 253-316 : 253

Platyceps josephi sp. nov. - Joseph's racer

Figs 14 , 15 , 16 , 17 , 18 , 19 , 20

Platyceps josephi "The Racer". - Whitaker and Whitaker 1986, p. 56 [lower image].

Zamenis fasciolatus . - Anonymous 1879, p. 35, Sclater 1891, p. 28 [patim]; Wall 1914, p. 34, pl. 22 [partim].

Coryphodon fasciolatus . - Beddome 1862, p. 16 f. [partim].

Argyrogena fasciolatus [sic]. - Whitaker 1978, p. 31. [partim, image p. 32]; Sharma 1982, p. 123 [partim]; Whitaker 1982, p. 31. [partim, image p. 32].

Argyrogena fasciolata . - Wilson 1967, p. 260 ff. [partim]; Whitaker and Captain 2004, p. 138 [partim]; Hutton and David 2008, p. 314; Rameshwaran, 2008: 22, front cover [partim]; Ganesh and Asokan 2010, p. 57; Vijayaraghavan and Ganesh 2011, p. 40 [partim, fig. 18]; Bhupathy and Satishkumar 2013, p. 4960; Chaitanya et al. 2018, p. 24; Sagadevan et al. 2019, p. 13567 [partim, image 1a,c].

Coluber fasciolatus . - Hutton 1949, p. 456; Rajendran 1986, part 1, p. 5, part 3, p.86-88, part 4, p. 1-4.

Platyceps josephi sp. nov. - this work.

Diagnosis.

A medium sized (maximum total length 951 mm) snake with countersunk lower jaw; dark brownish dorsum; head with irregular white spots, two slanting roughly “∏” shaped white markings with black edges on either side, starting on the back of the head (behind parietals) extending into the body, almost the length of head; 13-18 prominent white bands in the anterior region of the dorsum in both juveniles and adults; 34-48 total bands on the body in both juveniles and adults; 23:21(exceptionally 23):16-18 smooth dorsal scale rows; 189-218 ventrals (males: 192-197; females: 189-216); 76-88 subcaudals (males: 83-88; females: 76-88); cloacal plate divided; tail without bands and underside creamish. Its dentition is characterized by 12-16 maxillary teeth, the last two enlarged and separated by a diastema, 9-11 palatine teeth, 14-15 pterygoid teeth and 15-16 mandibular teeth.

Platyceps josephi sp. nov. shows most similarities with its sister taxon P. plinii in regard to pholidosis and colour pattern but can be distinguished from the latter by its lower number of midbody dorsal scale rows (21 vs. 23), its lower mean value of ventral scales (202 vs. 214), its lower mean value of subcaudal scales (82 vs. 87) and its lower mean of the sum of ventral and subcaudal scales (285 vs. 304), the presence of the clearly demarcated two slanting roughly “∏” shaped white markings on the back of head vs. absence of such markings and distinct white bands on the dorsum in both juveniles and adults vs. ontogenetic change, i.e. bands present in juveniles only, but usually absent or faded in adults. Additionally, Platyceps josephi sp. nov. differs from P. plinii in variation of mitochondrial DNA sequences. With pairwise uncorrected p-distances varying 4-5% in cytb & ND4 and 3% in 16S. It is also clear from our thorough verification of distribution that these two species only have a minor range overlap in northeastern Tamil Nadu (Fig. 1 Map).

Holotype.

NCBS AU-732 , adult female, from Tuticorin , Tamil Nadu state, India (8.75442° N, 78.18482° E, 5 m a.s.l) collected by Naveen Joseph on 26th February 2017 (Figs 14 - 16 A and 20 ).

Paratypes.

BNHS 3516 and NCBS AU-733, adult females, from Vagaikulam, Tuticorin, Tamil Nadu state, India (8.71634° N, 78.00203° E, 28 m a.s.l.), collected by Naveen Joseph on 28th July 2017 and 3rd Novembe r 2017, respectively. ZSI-CZRC-6639, adult male, from Karur, Tamil Nadu state, India (10.97382° N, 78.08949° E, 114 m a.s.l.) collected by Melvin Selvan on 2nd August 2018 and NMW 25465:2, juvenile male, from Salem, Tamil Nadu state, India (11.74178° N, 77. 93888° E, 314 m a.s.l.), collected by Ferdinand Stoliczka and donated to the NMW collection on 11th January 1879.

Referred specimens.

ZSI-CZRC-6521, adult female, from Tuticorin, Tamil Nadu state, India (8.73448° N, 77.97889° E, 33 m a.s.l.) collected by Naveen Joseph on 12th June 2017; ZSI-CZRC-6522, adult female, from Vilathikulam, Tamil Nadu state, India (9.125623° N, 78.176763° E, 20 m a.s.l.), collected by Ahmed Jerith and Naveen Joseph on 2nd February 2018; ZSI-CZRC-7358, sex unknown, from Anaikatti, Coimbatore district, Tamil Nadu state, India (11.11221° N, 76.75795° E, 581 m a.s.l.), collected by Jins VJ on 23rd Octobe r 2017; ZSI-K 12374, hatchling, from South India, presented by Edward Gerrard to the ZSI collection; ZSI-K 4379, hatchling, from Anamalai hills, collected by Richard Henry Beddome, and NMW 25465:1, juvenile female, from Salem, Tamil Nadu, India (11.74178° N, 77.93888° E, 314 a.s.l.) collected by Ferdinand Stoliczka. Because of the partly bad state of preservation or imprecise locality information we have excluded these specimens as potential type material.

Etymology.

The specific epithet is a patronym of late Mr Naveen Joseph. Naveen was a naturalist from Tuticorin, well known for his research on reptiles, particularly snakes in that region. He was a friend of VD, SN, and GM and helped them collect specimens of the new species. Suggested English name: Joseph’s racer. Vernacular name: In various parts of Tamil Nadu state this snake is called by the name "Odugali Pambu" “ஓடுகாலிப்பாம்பு”. It is a portmanteau word in Tamil language “Odugali” is often used to address someone "who doesn’t stay at home and elopes" and “Pambu” is the word for “snake”.

Description of the holotype.

Morphometric and merestic data are provided in Table 2 . Female. Specimen in good condition with three incisions into coelom at 80th, 106th and 123rd ventral respectively.

Body subcylindrical, dorsoventrally flattened. Head ovate, barely wider than the anterior end of body. Total lenghth 934 mm; snout-vent length 758 mm; tail length 176 mm; ratio tail length/total length 0.19; head length 24.0 mm; rostral large, 2.2 times broader than high, not protruding, rounded in dorsal view, and wedged in between internasals; the latter smaller (1.5 mm) and distinctly shorter along median suture than prefrontals (2.5 mm); mid-line suture between internasals and pre-frontals in straight line; distance from posterior tip of rostal to anterior edge of frontal 4.2 mm, the latter bell-shaped, 6.4 mm long with a maximum width of 4.7 mm; interocular width 7.0 mm; parietals 6.3 mm long, outer lateral and posterior margins of parietals surrounded by 13 scales between the upper postoculars; nasal completely divided, in contact with first and anterior half of second supralabial; nostril large in anterior shield; distance between posterior margin of nostril and anterior border eye 4.2 mm; loreal slightly longer (1.5 mm) than high (1.4 mm), in contact with posterior part of second and anterior half of third supralabial; preocular single, reaching top of head, touching frontal; presubocular squarish, smaller than preocular and loreal, in contact with third and fourth supralabial; 8/8 supralabials, fourth and fifth entering the eye, fifth highest; 2/2 postoculars, upper slightly broader, lower higher, lower postocular in contact with fifth supralabial; temporals in 2+3/2+3 rows, lower anterior slightly larger than upper; 9/9 sublabials, sixth largest, first five in contact with anterior inframaxillaries on both sides; anterior pair of inframaxillars broader and slightly longer (6.1 mm) than posterior pair (5.6 mm), which is distinctly separated by five inserted gulars; five gulars in a row between posterior edge of anterior inframaxillars and preventral; three preventrals and 203 ventrals; anal scute divided, right overlapping left; 76 paired subcaudals; terminal spine blunt; dorsal scales smooth, arranged in 23/21/17; apical pits present, but not consistently on all the dorsal scales, single or paired on dorsal part from the neck to near sacral region, single or triple pits present on dorsocaudal scales.

Dorsal scale reduction formula:

-3(6) +10(64) -10(67) +10(82) 10+11(87) 3+4(133) 8+9(151) -

23 ------- 21 ----------- 23 --------- 21 ----------- 23 -------------- 21 ------------ 19 ------------ 17 ---------- 18 (203).

-4(8) +11(65) -11(69) +11(84) -11(88) 3+4 (133) 8+9(150) +2(202)

Dentition (see Fig. 20 ).

14/16 maxillary teeth, the anterior 12/14 precranterian teeth are increasing in size posteriorly (from 0.9 to 1.6 mm length) and are followed by a diastema which is as long as the socket of the last precranterian tooth, and 2/2 slightly enlarged roundish cranterian teeth (~1.9 mm long) without groove. All maxillary teeth are slightly curved posteriorly, without significant interspaces. Medial to the precranterian teeth are single replacement tooth at different growth stages. One to 2 replacement teeth per cranterian tooth are found posteromedially to each tooth, showing different growth stages.

9/9 palatine teeth, decreasing in size posteriorly. All are curved posteriorly shortly above the base. Lateral to the palatine teeth there are single replacement tooth at different growth stages. No significant interspace exists between the different palatine teeth. Posteromedial process of palatine large, expanding two pterygoid teeth.

14/14 pterygoid teeth, decreasing in size posteriorly. All are curved posteriorly shortly above the base. Lateral to the pterygoid teeth there are single replacement tooth at different growth stages. No significant interspace exists between the different palatine teeth. The posterior 56% of the pterygoid are without teeth.

15/15 mandibular teeth, increasing in size up to tooth 6/6 and from there decreasing in size posteriorly. All are slightly curved posteriorly. Medial to the mandibular teeth there are 1-2 replacement teeth at different growth stages.

Hemipenis (based on ZSI-CZRC-6639, paratype, Karur, right organ, Fig. 19).

The hemipenis reaches up to 12th subcaudals and is 24.3 mm in length with a maximum width of 5.8 mm at 1/3rd of the proximal end. It is divided into three distinct areas; the proximal area (nearly 1/4th of the total hemipenial length) is smooth without any ornamentation, middle zone (about 28% of the total hemipenial length) is with spinulae and the apical calyculated portion (48% of the total hemipenial length). The spicules at the midbody of the hemipenis gradually reduce in size from proximal to the distal end. The calyculated area can be further divided almost equally into proximal half with large calyces and distal half with smaller and denser calyces. The sulcus spermaticus is single and runs straight across its length and opens into a wide and elongate naked area (3.3 mm) extending laterally from the proximal to distal end extending to the apex. The opening of the sulcus forms a triangular area and ends apically. The sulcus is bounded with thick walls. The calyces are larger proximally and gradually smaller and denser towards the distal end. The calyces distally are edged with papillae. Along the asulcate side, the spinous area starts more distally than the sulcate and lateral side. The proximal calyces are wider and elongated, with eight to nine well defined calyces extending towards the lateral side and the distal part of these calyces are scalloped. The calyces towards the distal part are with more of papiliated edges and are similar in micro-ornamentation with the sulcate side.

Variation among the paratypes.

See Table 2 for variations in merestic and morphometric features. Paratypes generally in moderate to good condition; NCBS-AU733, BNHS 3516 and ZSI-CZRC-6639 with single incision and NMW 24565: 2 without incision into the coelom. ZSI-CZRC-6639, male, both hemipenis removed for further examination. Tail/body ratio 0.22 in BNHS 3516, 0.13 in NCBS-AU733 and 0.23 in ZSI-CZRC-6639. Mid-line suture between internasals and pre-frontals not in a straight line in NCBS-AU733, BNHS 3516, NMW 24565: 2 and ZSI-CZRC-6639. Nostrils in BNHS 3516 situated above the center between both nasals. Loreals longer than high in NMW 24565: 2 and ZSI-CZRC-6639 and subequal in BNHS 3516. Temporals 2+3 (left), 2+2 (right) rows in ZSI-CZRC-6639; 2+3 (left), 2+2 (right) in NMW 24565: 2 respectively; 2+3 rows in the left side of BNHS 3516 and middle temporal in the second row (right) the largest than the other two and 2+3 on the left side of the NCBS-AU733 and the lower anterior temporal being the largest in all the paratypes on both sides. Posterior margin of the parietals surrounded by nine scales in BNHS 3516, fourteen scales in NCBS-AU733 and twelve scales in ZSI-CZRC-6639. Ten sublabials on both sides in BNHS 3516, NCBS-AU733, NMW 24565: 2 and ZSI-CZRC-6639 with only the first four in contact with the anterior inframaxillars in ZSI-CZRC-6639. One preventral in ZSI-CZRC-6639 and two pre-ventrals in NMW 24565: 2 and BNHS 3516 and preventrals absent in NCBS-AU733. Terminal scute sharp and intact in both BNHS 3516 and ZSI-CZRC-6639. Apical pits in BNHS 3516 and NCBS-AU733 are mostly single or double in the dorsal and double (single in few scales) above sacral but from the anterior part of the body, it is consistently double in all the scales from the position of the 10th ventral (single before that) until the tip of the tail for ZSI-CZRC-6639.

NCBS-AU733 differs from the holotype in having a slightly darker frontal and suprocular scales, presence of irregular white spots in the temporal scales, and a small white line along the midline between the two prefrontals. The first band on the body is separated from the “∏” shaped markings by 2 scales on both the sides along the lateral side. 46-48 bands on the dorsum from neck to vent, anterior 18 bands are prominent with white and black edges which fades and become wider towards the vent.

BNHS 3516 differs from the holotype by having dorsum darker, two prominent and two less prominent white spots parallel to each other in each parietal. The slanting “∏” mark behind the head, two corners starts from the first row of scales behind parietal but shifts to the next row of dorsal after 4 (right) and 5 (left) scales, the other two diagonal corners ends on the first dorsal scales near 4th ventral. There are 16 subequal horizontal bands on 2-3 dorsal scales, first band on the body separated from the “∏” shaped markings by three scale on right and two scales on left and all the other bands laterally connected with a mix of broken pale and black markings. There are 34 bands on the dorsum from neck to vent, anterior 16 prominent which becomes less prominent but wider towards the vent. ZSI-CZRC-6639 is overall similar to the holotype in the dorsum colours but with irregular white spots on the dorsal side of the head, a faint white spot at the junction of preocular, supraocular, prefrontal and frontal on both the sides; a faint white stripe in the anterior end of the frontal, the white spot in the suture between frontal and suproculars on both the sides, faint; 8-10 irregular spots together on both parietals. The slanting “∏” marking in the back of the head starts from the second row after the parietals on both the sides and continues towards the body but irregular. The first band on the body is separated from the “∏” shaped markings by 2 scales on both the sides along the lateral side. There are 42-44 bands on the dorsum from neck to vent, 14 prominent (white with black edges on each scale) which becomes less prominent but wider towards the vent. NMW 24565: 2 differs from holotype in having much lighter dorsum, by the presence of a white spot on the preocular-anterior frontal on both sides, two white spots along the midline suture on both parietals, one pair adjoining to frontal edge and other in the middle. The slanting “∏” shaped markings are much shorter extending only up to 7 rows of dorsal scales. About 39 visible bands on the dorsum of which anterior 13 are distinctly visible (see Figs 16 - 18 ).

Variation in dentition.

The male paratype from “Salem” (NMW 25465: 2) show 12/12 maxillary teeth followed by a distinct diastema which is 50% longer as the socket of the last precranterian tooth and two enlarged cranterian teeth, 11/11 palatine teeth with a posteriomedial process of palatine expanding three pterygoid teeth, 15/14 pterygoid teeth with 41% of the posterior pterygoid without teeth, and 15-16 mandibular teeth, increasing in size up to tooth 7/7 and from there decreasing in size posteriorly.

Pholidosis.

Head 1.25-1.99 times longer than broad (male 1.25-1.67, females 1.35-1.99). Rostral twice as broad as high and visible from above. Internasals (in midline suture) usually smaller than prefrontals. Frontals 1.32-1.59 times longer than the maximum width (male 1.40-1.59, females 1.32-1.42). Posterior border of parietals uneven in shape at the median suture forming an acute angle in ZSI-CZRC-6639 and NCBS-AU733 or both parietals uneven forming a slightly acute angle in BNHS 3516 or more or less straight with an obtuse angle in NMW 25465:2 and NCBS-AU-732. Posterior edge of parietals less than half the maximum width. Loreals usually longer than high or higher than long in NCBS-AU732 (on both sides). Preoculars single with a small pre-subocular present below it. Preocular usually in contact with frontal or rarely separated in, e.g., NCBS-AU733. Predominantly eight supralabials, usually last three being larger (in length), fifth highest. Fourth and fifth supralabials in contact with eye. Postoculars often two with the upper scale slightly wider than the lower scale that is usually higher or somewhat subequal in e.g., ZSI-CZRC-6639 and NCBS-AU732 in left side or lower scale smaller in ZSI-CZRC-6639 on the right side but in one specimen NMW 25565:2 with three postoculars on the right side. Usually two anterior temporals (on both sides). Secondary temporals variable, normally three but sometimes two in, e.g., NMW 25465: 2 and ZSI-CZRC-6639 (on right side) and BNHS 3516, NMW 25465: 2 and NCBS-AU732 (on left side). Mostly ten sublabials, sometimes nine in, e.g., NCBS-AU732 or eleven in NMW 25465: 2 (on both sides); the anterior four, rarely five in contact with first inframaxillary, sixth, rarely seventh largest in NMW 25465: 2. Anterior inframaxillaries normally longer than wider than the posterior ones except in BNHS 3516 and ZSI-CZRC-6522. The posterior pair of inframaxillaries usually separated by two or three rows of gular scales of variable shape and size. Gulars in four to five oblique rows between the apical edge of the posterior inframaxillaries and first ventral. Ventrals in examined material 189-218 (males 192-197, females 189-218). Usually, one or two preventrals, rarely without preventrals as in NCBS-AU733. Anal scute divided right part overlapping left part. Subcaudals in 76-88 in pairs (males 82-88, females 76-88). Total body scales, including preventrals and terminal scale 275-297 (males 276-288, females 275-297).

Dorsal scale rows (DSR), usually arranged in 23-24/21, rarely 23/17 or sometimes 18 rows along the trunk. One male specimen from Karur shows anterior 24 DSR; Midbody DSR predominantly 21 except in one specimen ZSI-CZRC-6639 with 23 DSR and two specimens NCBS-AU732 and NCBS-AU733 shows 18 DSR and one specimen ZSI-CZRC-6521 shows 16 DSR in posterior part of the body.

Dorsal scales with single or paired apical pits. Supracaudal scales usually with one to three pits on the first three to five scales followed the supracaudal reduction. In male (ZSI-CZRC-6639), consistently two pits from the midbody to the last supracaudal scale.

Dorsal scale reduction formula summarized from five examined specimens (see Appendix 10). Only main reductions are given.

4+5(6) 3+4(6-13) 2+3 or 3+4(116-133) 7+8 or 8+9 (144-151)

24 -------- 23 --------------------- 21 -------------------------- 19 --------------------------- 17.

- 2+3 or 3+4(6-13) 3+4 (115-133) 7+8 or 8+9 (142-151)

Two examined specimens (NCBS-AU732, holotype, and NCBS-AU733) and one specimen (ZSI-CZRC-6521) show an additional lateral increase to 18 and reduction to 16 dorsal scales involving rows 1-3 between 95 and 99% of ventral scales respectively.

Dimensions and proportions.

The body robust, moderately stout, roundish in cross section at midbody. Head moderately pointed, barely distinct from neck or sometimes slightly distinct. Eye large with black round pupil, 16-25% of head length. The longest examined specimens are from Karur (ZSI-CZRC-6639), a male specimen with 740 mm and a female from Tuticorin (ZSI-CZRC-6521) with 951 mm total length. The smallest specimens are from Salem including a male (NMW 25465: 2) with 582 mm and female (NMW 25465:1) with 315 mm total length. The tail/body length ratio ranges from 0.15 to 0.32 (males 0.29-0.32, females 0.15-0.32).

Distribution.

Platyceps josephi sp. nov. is so far only known from Tamil Nadu state, India (see Fig. 1 Map). It is reported from the Anaimallai Hills and different localities within the districts of Coimbatore (Anaikatti, Coimbatore, Pollachi), Dindigul (Batlagundu), Kanyakumari (Maruthuvazhmalai), Karur (Karur), Madurai (Madurai, Vadipatti), Salem (Salem), Theni (Meghamalai Hills), Thoothukudi (Tuticorin), Tirunelveli (Coutrallam, Manimutharu, Tirunelveli) and Villupuram (Auroville) (see Appendix 9 Gazetteer and Appendix 10).

Habitat and natural history.

Platyceps josephi sp. nov. mostly inhabits open habitats with sandy or rocky patches in grasslands and scrublands in both inland and coastal areas of Tamil Nadu from elevations between 10 and 580 m a.s.l. (see Fig. 21 and Appendix 9). Most of the areas where they occur receive less than 500 mm annual rainfall except locations near the rain shadowed areas close to the Western Ghats receives higher rainfall (Anaikatti and Megamalai) (http://www.tnsccc.in/rainfall.php). Sagadevan et al. (2019) report a sighting from the dry evergreen forest in Auroville, Villupuram district, but it is pertinent to mention here that this region was originally a scrub jungle and the current dry evergreen forest is an anthropogenic habitat created a few years ago ( Blanchflower 2005). Platyceps josephi sp. nov. is usually observed under thorny bushes, rock boulders, paddy fields, heaps of dry coconut fronds and seen crossing roads ( Rajendran 1986; NJ and MS personal observation). The holotype (NCBS-AU732) and the paratype (BNHS 3156) were both collected from human habitations. ZSI-CZRC-6639 was found under heaps of coconut fronds within a plantation surrounded by dry grasslands. NCBS-AU733 was collected from under a woodpile near a farmhouse surrounded by grassland. Two other referred specimens (ZSI-CZRC 6521 and 6522) from Tuticorin and one specimen (ZSI-CZRC-7358) from Anaikatti, Coimbatore were collected as roadkilled. It appears to be an uncommon snake in all known locations. However, in the past at least in Megamalai hills, it was recorded to be "fairly common" in the dry deciduous forests ( Hutton 1949). The late Naveen Joseph and his team, who maintain a record for snake rescues in and around Tuticorin, had seen only 16 individuals in the 18 years between 2002 and February 2021.

Platyceps josephi sp. nov. is a diurnal snake, terrestrial and swift in locomotion. However, there is a report of arboreal behaviour under artificial conditions ( Rajendran 1986), but this is not known in the wild. It is an aggressive snake, flattening its head as a mock hood display mimicking a cobra, when agitated and biting freely, but it becomes docile after a few days in captivity (Rajendran, 1986; Hutton, 1949). Similar behaviour was observed during this study for specimens from Tuticorin, Tamil Nadu (NCBS-AU732, NCBS-AU733 and BNHS 3516).

The diet of the P. josephi sp. nov. chiefly consists of geckos, lizards and small rodents. It is observed to kill the prey by constricting and/or crushing the prey against ground or tree trunk. In all captive observations, it swallows the prey from the head first. It is an oviparous snake with few records of clutch sizes, 7-12 eggs ( Hutton 1949; Rajendran 1986; Rameshwaran 2008), during the month of March and June and were 40 mm in length ( Rameshwaran 2008). Females are reported to lay their eggs in bunds (raised areas surrounding the paddy fields) of paddy fields ( Rajendran 1986).

Platyceps josephi sp. nov. is reported only from one protected area (Megamalai) in its known range. The species faces a number of threats across its distributional range, including habitat destruction, because the grasslands in southern Tamil Nadu are being actively converted into plantations, farmlands and urbanisation. Although there are records from such converted plantations and human settlements,the species’ ability to adapt and its reproductive success is not known. Rocky habitats in Madurai region are also highly affected by the mining activities and road traffic is another important threat to P. josephi sp. nov. Three out of the seven specimens collected in this study were roadkilled and six other uncollected roadkilled specimens were observed from various parts of Tamil Nadu between 2017 and 2020. The Area Of Occupancy (AOO) of P. josephi sp. nov. is 72.000 km2 and Extent Of Occupancy (EOO) is 70,698 km2. Even though this is a relatively large area of distribution for a species, our field surveys and records suggest that this species has patchy distribution within its range. Also, much of the habitat in these regions where P. josephi sp. nov. is reported are under severe threats like conversion of grasslands to farmlands, widescale monoculture plantations ( Eucalyptus sp.) and urbanization. Given this information, we suggest that P. josephi sp. nov. should be considered a species in the Vulnerable category according to the IUCN criteria.

Although local envenoming by congeners is reported for P. rhodorachis and P. najadum ( Minton 1990; Kuch and Mebs 2002; Weinstein et al. 2011), bites from P. josephi sp. nov. seem to be harmless and without any local symptoms. Rajendran (1986) reported two bite cases, one being himself got bitten while trying to catch an individual in a paddy field and another for an adult male got bitten while harvesting the paddy. No local symptoms were observed after a bite from a later preserved specimen (BNHS 3516, paratype) to one of the authors (NJ) upon handling.

Juvenile Platyceps josephi sp. nov. can easily be confused with juveniles of Platyceps plinii but may be differentiated by the two slanting roughly “∏” shaped markings on the back of the head. Platyceps josephi sp. nov. is found in sympatry with the Common cobra ( Naja naja ) and the Common ratsnake, Ptyas mucosa , and can potentially also be confused with these two species.

Differences between Platyceps josephi sp. nov. and South Asian congeners.

Platyceps josephi sp. nov. is distinguished clearly from P. bholanathi , P. mintonorum , P. noeli , P. rhodorachis , P. sindhensis and P. ventromaculatus by its higher number of midbody dorsal scale rows (21 vs. 19) and from P. gracilis by its lower mean value of ventral scales (202 vs. 214), its lower value of subcaudal scales without overlapping (88 maximum vs. 118 minimum), its different neck pattern (whitish ∏-shaped marking vs. a yellowish-cream and black edged V-shaped marking), and by differing dorsal body pattern (irregular whitish transverse bars stippled with black vs. dorsal yellowish-cream and black-edged transverse bars). Platyceps josephi sp. nov. shows similarities with P. plinii with regard to pholidosis and colour pattern but can be distinguished from the latter by its lower number of midbody dorsal scale rows (21 vs. 23), its lower mean value of ventral scales (202 vs. 214), its lower mean value of subcaudal scales (82 vs. 87), and its lower mean of the sum of ventral and subcaudal scales (285 vs. 304).

Comparision of Osteology.

The first detailed description of osteological features of Platyceps plinii were based on a male and a female specimen ( Fraser 1936). Later, Wilson (1967) studied 15 preserved specimens of the Banded racer, including two disarticulated skeletons, and compared it among other species formerly allocated to the genus Coluber with material of racer-like genera including Asian species currently placed in Platyceps (e.g. elegantissimus, Platyceps florulentus , Platyceps gracilis , Platyceps karelini , Coluber najadum , Platyceps rhodorachis , Platyceps rogersi , thomasi, variabilis and Platyceps ventromaculatus ) as well as Dolichophis jugularis , Hemorrhois ravergieri and with Orientocoluber spinalis . He described several osteological characters which he used to delimit C. fasciolatus from other species of Coluber (sensu lato) and, because of differences from other racer-like genera he resurrected the genus Argyrogena Werner for the Banded racer.

In his comparison, Wilson (1967) stated that the premaxilla of Argyrogena is short and stout and its lateral processes are posteriorly orientated, whereas Coluber (sensu lato) has a longer premaxilla with more nearly transverse processes. In Argyrogena the nasals are stout, overlap the ascending process of premaxilla to some extent and posteriorly cover the nasal capsule more than in Coluber (sensu lato), there is nearly no overlap between nasals and premaxilla. He further states that the pterygoid of Argyrogena show a medial flange on the bone with the result that the teeth are situated near the center of the pterygoid rather than along its medial edge as in the other species of Coluber (sensu lato), which have no medial flange. Additionally, he writes that the tooth rows on the pterygoid bones converge posteriorly, whereas in Coluber (sensu lato) the rows diverge and furthermore that the pterygoid processes at the basioccipital are lacking in Argyrogena , but well developed in Coluber (sensu lato). Beside skull morphology, he also studied the postcranial skeleton and included characters of midbody and caudal vertebrae in his investigation. He stated that in Argyrogena at the midvertebrae the accessory process is shorter and more dorsolaterally orientated and the ventral aspect of the centrum is stouter and that the transverse processes of the caudal vertebrae are broad based and show a prominent notch between the posterior edge of each process and the centrum.

Some of the osteological characters used by Wilson (1967) were later specified and their phylogenetic significance assessed by Schätti (1987). The latter did not include Argyrogena in his analysis but indicated extensive sexual, ontogenetic, geographical or uncorrelated intraspecific variation in old world racers. Schätti (1987) refused to use dentition to separate distinct groups as "The total number of teeth, their absolute length, the presence of a diastema, as well as the enlargement of the teeth posterior to the diastema is subject to considerable variation." For this reason, he considered osteological characters as diagnostic to delimit Palearctic from Nearctic groups, but only the shape and size ratios of the vertebrae show distinct characters to separate Platyceps from other Palearctic genera because craniological features may show remarkable intraspecific variation.

Schätti (1987) took into account (1) length of centrum/least width of neural arch (LC/WN), (2) length of centrum/width across prezygapophyses between outer edges of articular facets (LC/WP), (3) length of neural spine/least width of neural arch (LN/WN), but emphasizes that especially the ratio (1) is useful for delimitation, because it varies only within narrow limits (see Appendix 6 for the description of the measuring distances).

Recently, Das et al. (2019) provided a detailed skull description based on six specimens of the Banded racer and distinguished it from Platyceps mainly by its longer and elongated nasal horizontal lamina. The latter authors also mentioned a backward curved transverse process in contrast to a laterally directed narrow transverse process in Platyceps , but did not name the belonging bone. We assume they were describing the premaxillary transverse processes. Finally, they separated Argyrogena from Platyceps by the existence of a mesial transverse process at the pterygoid vs. no mesial transverse process.

In contrast to the former studies on Argyrogena mentioned above, material examined by us lead to different results (see also Appendix 7 and 8). In all examined Platyceps species lateral processes of the premaxilla are always curved posteriorly, but with variable length. This can result in short lateral processes as described by Wilson (1967) and Das et al. (2019) and can be found in P. plinii comb. nov., P. josephi sp. nov., and P. rhodorachis , but also in longer lateral processes as present in P. florulentus , P. rhodorachis , P. ventromaculatus and also in P. plinii comb. nov. Furthermore, we found that short lateral processes lead to a more pointed snout, thus a projected rostrum, a condition also commonly used as a key character to separate Argyrogena from Platyceps (see e.g. Wilson 1967; Rajabizadeh et al. 2020). However, a projected rostrum of variable expression and a countersunk lower jaw is also reported for different Platyceps species by Schätti et al. (2014; see also comments below).

We found differences within the distal ends of the lateral processes of the premaxilla, which either are tapering into a single tip in P. plinii comb. nov., P. josephi sp. nov., and P. rhodorachis , expanded and divided into two tips in P. florulentus or expanded into a stout end in P. rhodorachis as well as in P. ventromaculatus . Because of this considerable intraspecific variation, we regard the form of the lateral processes of the premaxilla as an inappropriate character to delimit Argyrogena from Platyceps .

Das et al. (2019, p. 313) stated that the premaxilla in Argyrogena has no nasal process but in contrast to that, a short (ascending) process is shown in the sketch (Fig. 1 B , lateral view). In all examined specimens we found an ascending process of the premaxilla, which varies in length and can be clasp by the anterior process of the nasals. If the ascending process of the premaxilla is longer than the lateral processes, we define them as ‘long’, e.g. in P. rhodorachis and P. ventromaculatus otherwise as ‘short’ as in found in P. plinii comb. nov., P. josephi sp. nov. and P. florulentus .

Wilson (1967) noted that the anterior processes of nasals overlapping the ascending process of premaxilla in Argyrogena vs. less overlap of nasals and ascending process of premaxilla in Coluber (sensu lato). We found this overlap in all examined species, whereby the nasals can be in contact with the ascending process of premaxilla in P. plinii comb. nov., P. josephi sp. nov., P. florulentus and P. ventromaculatus or just have a loose connection as in P. rhodorachis . Since this is a variable character and its presence in the Banded racer and Platyceps spp., makes this an inappropriate character for distinguishing genera.

Furthermore, Wilson (1967) described the nasals of Argyrogena as stout, as was verified by our analysis. The Banded racer, P. plinii comb. nov., has the most compact nasal bone of all Platyceps examined (TLn/TWn range 0.93-1.04), distinguished by the following values, viz. P. josephi sp. nov. (TLn/TWn range 1.16-1.18), P. florulentus (TLn/TWn 1.24), P. rhodorachis (TLn/TWn range 1.27-1.39), and P. ventromaculatus (TLn/TWn 1.28).

Wilson (l. c.) mentioned that in Argyrogena the nasal shield posteriorly expands dorsolaterally to cover the nasal capsule more completely as in the other Coluber (sensu lato). Our measurements show that the nasal shield of the Banded racer tends to be shorter (TLln/Lns range 40%-50%) than in other examined Platyceps spp. (TLln/Lns range 56%-77%) and therefore covers only a smaller part of the nasal capsule. Our comparison of the nasal shields revealed that it covers in P. plinii comb. nov. the posterior part of the nasal capsule completely, whereas in the other examined Platyceps spp. (excluding Platyceps josephi ) only the middle part of the nasal capsule is enclosed. This resulted in a larger gap between the nasal shield and the frontal. Platyceps josephi sp. nov. shows an intermediate state regarding this character as the nasal shield do enclose the posterior part of the nasal capsule but shows a larger gap than observed in P. plinii comb. nov. This character seems to be highly influenced by the lifestyle of the species and varies considerably interspecifically ( Schätti 1987).

Wilson (1967) and Das et al. (2019) identified the presence of a medial flange at the pterygoid bone (with teeth) are situated near the centre of the pterygoid rather than along its medial edge vs. no such medial flange as a main character to separate Argyrogena from Coluber (sensu lato) and Platyceps spp. This condition was not mentioned by Fraser (1936) and in Banded racer skulls studied by us, this medial flange is present in 60% of the examined specimens only (see Fig. 12 D , medial flange absent). It is always present in P. josephi sp. nov., (see Fig. 20 D ) but lacking in P. florulentus , P. rhodorachis and P. ventromaculatus .

Another character listed by Wilson (l. c.) as typical for Argyrogena deals with the pterygoid teeth row, which converges posteriorly in the Banded racer but diverges in Coluber (sensu lato). We cannot follow this observation as in all examined specimens the teeth row follows the medial edge of the pterygoid bone and therefore always converge posteriorly.

Wilson (l. c.) also described the pterygoid processes at the basioccipital which he mentioned as clearly visible in e.g. Platyceps karelini , P. ventromaculatus , Dolichophis jugularis and Hierophis viridiflavus but lacking in Argyrogena . In Platyceps spp. examined by us, we found a high variability of this character, ranging from a basioccipital without structures, with three or five small tips or sometimes with a high crest. Our comparison of different development stages of D. jugularis , H. gemonensis and H. viridiflavus show that in juveniles such structures are lacking while in adults, high crests and tips appear and the expression of this character is very likely age-dependent.

Differences in midbody vertebrae morphology of racer species is highlighted as a character of phylogenetic significance ( Schätti 1987) and is compared here with the next related taxa. Vertebrae have been described and compared for Argyrogena and Coluber (sensu lato, including Platyceps ) by Wilson (1967), for old world racers in general by Schätti (1987) and for Platyceps by Schätti et al. (2014).

Wilson (1967) stated that in Argyrogena the accessory processes at the mid-vertebrae are shorter and more dorsolaterally orientated as in Coluber (sensu lato). Based on Auffenberg’s (1963) definition, Schätti (1987) defined the same character as ratio of the length of centrum to the width across prezygapophyses between outer edges of articular facets (LC/WP) (see Appendix 6-8). Our analysis of this character revealed, that intraspecific variation can be very low as in P. ventromaculatus (LC/WP range 0.76-0.86), but also more variable, e.g. in P. rhodorachis (LC/WP range 0.55-0.88). The total range of ratio LC/WP for Platyceps spp. examined ranges from 0.55-0.88 and included, with a wide overlap, the Banded racer, Platyceps plinii comb. nov. with a LC/WP ratio range from 0.73-0.95 (see Appendix 7 and 8). Furthermore, this character state cannot be used to delimit the Banded racer and other Platyceps spp. from next related genera because of overlapping values as determined for Hemorrhois nummifer (LC/WP range 0.63-0.71), H. ravergieri (LC/WP range 0.66-0.86) and Spalerosophis diadema (LC/WP 0.62).

According to Wilson (1967) the ventral aspect of the centrum of middorsal vertebrae in Argyrogena is stouter than in Coluber (sensu lato). Schätti (1987) used this character as quotient of the length of centrum and the least width of neural arch (LC/WN), based on Auffenberg’s (1963) definition. Our analysis of this character shows that for the Banded racer the values vary from 1.21-1.59 with lower extremes below the range of other Platyceps species with an LC/WN range from 1.32-1.70. But also this character does not allow reliable distinction between Platyceps spp. (LC/WN range 1.21-1.70) and Hemorrhois ( Hemorrhois nummifer 1.22-1.39; Hemorrhois ravergieri 1.20-1.61). Although Spalerosophis diadema is distinguished here by the lowest value (LC/WN 1.08) it is based on a single examined specimen only and the variation for this character is not sufficiently studied for this species (see Appendix 6-8). As further character Schätti (1987) defines the ratio of length of neural spine to least width of neural arch (LN/WN) as highly variable throughout the vertebral column in Holarctic racers. The analysis of this trait with respect to the position of the Banded racer to Platyceps and other related genera revealed that the Banded racer tend to lower values (LN/WN range 0.81-1.01) but overlap to some degree the other examined Platyceps spp. (LN/WN range 0.95-1.27). Similarly, to the conditions shown for the Banded racer the values for H. nummifer (LN/WN range 0.84-1.07), H. ravergieri (LN/WN range 0.80-1.16) and S. diadema (LN/WN 0.80) lie near to the lower variation range of all examined Platyceps (LN/WN range total 0.81-1.27) (see Appendix 6-8).

Wilson (1967) used also the structure of caudal vertebrae to delimit Argyrogena from Coluber (sensu lato) and described the transverse processes of it as broad-based proximally with a prominent notch between posterior edge of each process and the centrum. In contrast to that, he described for Platyceps karelini , P. najadum and P. rhodorachis the processes as rather broad-based proximally, but not as much as in Argyrogena and without a posterior notch. In contrast to Wilson (l. c.) we found in five examined specimens of the Banded racer and four other Platyceps spp., including P. josephi sp. nov., the transverse processes of the caudal vertebrae as broad based but with striking differences between the sexes. In all males the transverse processes are directed laterally, the base occupies ~ 75% of the centrum and show a posterior notch, the latter characterized by considerable variability in expression even within a single individual. Contrary to males, the processes in females are directed anterio-laterally with a much shorter base which occupies not more than 60% of the centrum and show a posterior notch with the same degree of variability as in males. For specimens studied by us, we conclude that this character is sex dependent and qualifies no differentiation between Argyrogena and Platyceps .

In summary, it is evident that Argyrogena shares most osteological characters with Platyceps . Previous use of skeletal traits to underpin the distinctness of the genus Argyrogena is shown invalid, with the exception of the form of the nasal shield as the only distinguishing character to the previous known Platyceps spp. But with respect to the latter character, Platyceps josephi sp. nov. show an intermediate state and linked the Banded racer with Platyceps . We therefore consider Argyrogena Werner, 1924 a junior subjective synonym of Platyceps Blyth, 1860 and relegate the Banded racer (auctt.) to the genus Platyceps in the new combination Platyceps plinii (Merrem, 1820) (see the also conclusions in previous chapters).

Figures

Figure 1. Map showing geomorphological features in parts of the Indian subcontinent and current locality records (see Appendix 9) for Platyceps spp. mentioned in this study. Green (triangle) denotes the type locality and green (diamonds) for records of P. plinii comb. nov. Yellow (star) denotes the type locality, and yellow (circles) for the records of P. josephi sp. nov. Historically relevant names and important physiographic features are labelled.

Figure 12. Skull of Platyceps plinii comb. nov. (BMNH 37 a) from Visakhapatnam, Andhra Pradesh state, India: A. lateral, B. ventral (tooth bearing and connecting bones virtually extracted), C. dorsal and D. ventral view (lower jaw virtually extracted). Scale bar 1.5 mm.

Figure 14. Holotype of Platyceps josephi sp. nov. (NCBS-AU 732) in preservation, from Tuticorin, Tamil Nadu state, India: A. dorsal and B. ventral view. Scale bar 10 mm.

Figure 15. Line drawings showing head scalation and dimensions of the holotype of Platyceps josephi sp. nov. (NCBS-AU 732) from Tuticorin, Tamil Nadu state, India: A. dorsal, B. ventral, C. lateral right and D. lateral left view. Scale bar 10 mm.

Figure 16. Platyceps josephi sp. nov. in life from various parts of Tamil Nadu state, India: A. Holotype NCBS-AU 732 (female, SVL: 757) from Tuticorin, B. Paratype NCBS-AU 733 (female, SVL: 608) from Tuticorin, C. Paratype BNHS 3516 (female, SVL: 592) from Tuticorin, D. uncollected (juvenile) from Tuticorin, E. Paratype ZSI-CZRC- 6639 (male, SVL: 574) from Karur, F. Uncollected (male) from Vathalagundu, G. uncollected (juvenile) from Tuticorin and H. uncollected (female, SVL: 655) from Pollachi. SVL in mm.

Figure 17. Platyceps josephi sp. nov., dorsal view of preserved paratypes from Tamil Nadu state, India: A. ZSI-CZRC- 6639 (male, SVL: 574), from Karur, B. NCBS-AU 733 (female, SVL: 608) from Tuticorin, C. NMW 25465: 2 (male, SVL: 440) from Salem, and D. BNHS 3516 (female, SVL: 592) from Tuticorin. Scale bar 10 mm.

Figure 18. Platyceps josephi sp. nov. Variation of neck pattern in specimens from various parts of Tamil Nadu state, India. Adults: A. Paratype, ZSI-CZRC- 6639 (male, SVL: 756) from Karur, B. Paratype, BNHS 3516 (female, SVL: 592) from Tuticorin, C. Paratype, NCBS-AU 733 (female, SVL: 608) from Tuticorin. Hatchlings / juveniles: D. Paratype, NMW 25465: 2 (male, SVL: 440) from Salem, E. ZSI 4379 (sex unknown, SVL: 204) from Anamalai hills, and F. ZSI-K 12374 (sex unknown, SVL: 242) from South India without specified locality. Scale bar 10 mm; SVL in mm.

Figure 19. Hemipenis of Platyceps josephi sp. nov. (ZSI-CZRC- 6639, paratype, right organ) from Karur, Tamil Nadu state, India: A. lateral, B. asulcal, and C. sulcal view. Scale bar 10 mm.

Figure 20. Skull of the holotype of Platyceps josephi sp. nov. (NCBS-AU 732) from Tuticorin, Tamil Nadu state, India: A. lateral, B. ventral (tooth bearing and connecting bones virtually extracted), C. dorsal and D. ventral view (lower jaw virtually extracted). Scale bar 2.0 mm.

Figure 21. Habitats of Platyceps josephi sp. nov. in Tamil Nadu state, India: A. close to the coast at the type locality Tuticorin, and B. inland habitat near Anaikatti, Coimbatore.