Stegonotus iridis, Ruane & Richards & McVay & Tjaturadi & Krey & Austin, 2017

Ruane, Sara, Richards, Stephen J., McVay, John D., Tjaturadi, Burhan, Krey, Keliopas & Austin, Christopher C., 2017, Cryptic and non-cryptic diversity in New Guinea ground snakes of the genus Stegonotus Duméril, Bibron and Duméril, 1854: a description of four new species (Squamata: Colubridae), Journal of Natural History (J. Nat. Hist.) 52 (13 - 16), pp. 917-944 : 924-928

Stegonotus iridis sp. nov.

( Figures 2−5 , Table 1, Appendix 1)

Holotype

MZB. Ophi. 3306 (field number SJR 7623 , tissue ABTC 90141 ), adult male. Collected by S. Richards, B. Tjaturadi and K. Krey on 9 June 2005 from Warinkabom , Batanta Island, Raja Ampat Regency, West Papua Province, Indonesia, elevation 50 m above sea level (asl) (0.836942°S, 130.72162°E) ( Figure 5 ).

Paratypes

SAMA R 70466 (field number SJR 7514 , tissue ABTC 90088 ) collected by S . Richards, B . Tjaturadi and K . Krey on 5 June 2005 from Waire Camp , Batanta Island, Raja Ampat Regency, West Papua Province, Indonesia, elevation 25 m asl (0.839738°S, 130.525546°E); MZB . Ophi . 3305 (field number SJR 7624 , tissue ABTC 90142 ) collected by S . Richards, B . Tjaturadi and K . Krey on 11 June 2005 from Urbinasopen , Waigeo Island, Raja Ampat Regency, West Papua Province, Indonesia, elevation 45 m asl (0.337183°S, 131.258800°E); MZB . Ophi . 3303 (field number SJR 7691 , tissue ABTC 90173 ) collected by S . Richards, B . Tjaturadi and K . Krey on 18 June 2005 from Yakut Camp , Batanta Island, Raja Ampat Regency, West Papua Province, Indonesia, elevation 55 m asl (0.895817°S, 130.641633°E); MZB . Ophi .3311, MZB. Ophi . 3302 (field numbers SJR 7794 , tissue ABTC 90230 ; SJR 7793 ,

a

b

Includes number of individuals examined for morphology (n), number of midbody dorsal scale rows (rows), range of ventral scale number (ventral), range of subcaudal scale number (sub), number of supralabial scales (supr), number of infralabial scales (infr), number of preocular scales (pre), number of postocular scales (post), presence of apical pits (aps), generalized ventral/ subcaudal patterns (venter/sub pattern) and generalized labial patterns (labial pattern). New Guinean species indicated by *, mainland New Guinea by**. In cases of multiple numbers of scales the number in bold type represents the majority of specimens examined here. Specifics for individual specimens and additional morphological characters are in Appendix 1. A single Stegonotus derooijae sp. nov. was found with apical scales present, indicated by

†.

tissue ABTC 90229 ), collected by S . Richards, B . Tjaturadi and K . Krey on 27 and 28 June 2005 from Waibya , Salawati Island, Raja Ampat Regency, West Papua, Indonesia, elevation 75 m asl (0.956383°S, 130.784333°E) .

Referred specimens

MZB.Ophi. 3301 ( SJR7805 , morphology only), collected by S . Richards, B . Tjaturadi and K . Krey on 27 and 28 June 2005 from Waibya , Salawati Island, Raja Ampat Regency, West Papua, Indonesia, elevation 75 m asl (0.956383°S, 130.784333°E) .

Diagnosis

A new species of Stegonotus that can be diagnosed from its congeners by the following combination of characters: a completely white or white with a brownish washed, iridescent dorsum, with or without brown or black speckling which increases posteriorly, an immaculate white venter and white subcaudal scales or, in individuals that are more heavily pigmented dorsally, a white venter with a brownish wash increasing in intensity posteriorly, brown or black pigmentation on the dorsal scales of the head (including rostral, internasal, prefrontal, frontal, parietals, loreal, supralabial and ocular scales) usually extending down the neck two or three scale rows before fading away, 19 dorsal scale rows at midbody (infrequently 17), the absence of apical pits on dorsal scales, 198−211 ventral scales and 78−88 divided subcaudal scales, eight (infrequently nine) supralabial scales and 10 (infrequently nine) infralabial scales, with supralabial scales brownish or blackish and infralabial scales either white or, in highly pigmented individuals, brownish or blackish.

Description of holotype

Adult male in excellent state of preservation, with a short ventral slit midbody and hemipenes exposed, not fully expanded. Body shape is robust. Snout–vent length 713 mm with 201 ventral scales, tail length 238 mm with 88 divided subcaudal scales. Anal scale single. Head length 28.3 mm, as measured from the snout to the rear of the quadrate, width 14.9 mm as measured across the widest point of the head anterior to the quadrate. Eyes 3.6 mm horizontal diameter, pupil shape subcircular. Supralabials eight with the fourth and fifth in contact with the eye. Infralabials 10, with first pair in contact behind mental, infralabials one to five in contact with inframaxillaries. Rostral broader than high, 5.6 mm wide/ 4.5 mm high, visible from above. Nasal in contact with first supralabial. Single loreal, in contact with nasal, preoculars, prefrontal and supralabials one, two and three and slightly extending as to barely contact the eye. Circumoculars five: one supraocular, two preoculars, zero suboculars and two postoculars. Anterior temporals two. Dorsal surface of head includes pair of internasals (width 3.6 mm /length of suture 1.4 mm), pair of prefrontals (width 5 mm /length of suture 4.4 mm), pair of supraoculars (width 2.7 mm /length 4.1 mm), frontal longer than wide (length 6.5 mm /anterior width 6.4 mm), pair of parietals (length of suture 7.9 mm). Two pairs of inframaxillaries (anterior inframaxillary suture length 4.2 mm, posterior inframaxillary suture length 2.9 mm), posterior inframaxillaries in contact with each other. Dorsal scale rows 17−19−15 (15th ventral from anterior, midbody, and 15th ventral anterior to cloaca).

Coloration in life

Dorsal coloration behind head white with no pattern or markings. Colour of iris black. Dorsum of head, including rostral, internasals, prefrontals, frontal, supraoculars and parietals, brown with white edges at the suture of most scales; several scales immediately posterior to the head with brown edges. Supralabials light brown/tan, infralabials white with light brown/tan pigment towards the ventral side of the scales. Ventral and subcaudal scales immaculate white and iridescent.

Coloration in preservative

Dorsal coloration in preservative of body posterior of head iridescent white with no pattern or markings down the entire dorsal side of the body and tail. Colour of iris opaque grey. Dorsum of head, including rostral, internasals, prefrontals, frontal, supraoculars and parietals, similar to coloration in life: brown with white edges at the suture of most scales; several scales immediately posterior to the head with brown edges. Supralabials light brown/tan, infralabials white with light brown/tan pigment towards the ventral side of the scales. Ventral and subcaudal scales immaculate white and iridescent.

Variation

Paratypes are similar to the holotype excepting the following: MZB.Ophi.3305 with 17 rather than 19 midbody dorsal scale rows, possibly nine rather than eight supralabials on the left (unclear), darker head pigmentation, dark speckling increasing posteriorly and a brownish-grey wash on the ventral and subcaudal scales; MZB.Ophi.3302, MZB.Ophi.3311, and MZB.Ophi.3301 with a brownish wash on the dorsal scales SAMA R70466 with 206 ventrals, 69 subcaudals (missing tail tip); MZB.Ophi.3305 with 198 ventrals, 78 subcaudals; MZB.Ophi.3303 with 203 ventrals, 83 subcaudals (missing tail tip); MZB.Ophi.3302 with 205 ventrals, 85 subcaudals; MZB.Ophi.3311 with 204 ventrals, 85 subcaudals; MZB.Ophi.3301 with 211 ventrals, 85 subcaudals.

Etymology

The species epithet is a noun in apposition and taken from the Latin word for rainbow. It refers to the high level of iridescence shown both dorsally and ventrally by this species.

Natural history and distribution

Currently known only from the Raja Ampat islands of Batanta, Salawati and Waigeo in eastern Indonesia where all of the animals encountered were active on the forest floor in moderately to heavily disturbed lowland (<100 m asl) rainforest at night. The pale colour of this species made them extremely conspicuous against the dark forest floor.

Comparisons

The white or off- white dorsal and ventral colour of Stegonotus iridis sp. nov., with a dark coloured head that includes white edges on most head scales, is unique for the genus. Although S. cucullatus has a pale phase that includes cream or yellowish-tan coloured dorsal scales with black edges resulting in a reticulated dorsal pattern ( Figure 1 (a)), the base coloration is not as white and appears more cream to tan when compared with S. iridis sp. nov. ( Figures 2 , 4 , 5 ).

Figures

Figure 1. Photographs of six New Guinea Stegonotus species in life including voucher numbers: (a) Stegonotus cucullatus LSUMZ 94371, (b) Stegonotus diehli LSUMZ 92345, (c) Stegonotus modestus LSUMZ 92327, (d) Stegonotus heterurus BPBM 22556, (e) Stegonotus parvus LSUMZ 92335, (f) Stegonotus guentheri LSUMZ 94386. Photos from Christopher C. Austin (a, b, c, e, f) and F. Kraus (d).

Figure 2. Photographs of Stegonotus species with dorsal, ventral and lateral head views from left to right: (a) Stegonotus batjanensis USNM 237129, (b) Stegonotus borneensis FMNH 251054, (c) Stegonotus muelleri LSUMZ 41802, (d) Stegonotus florensis WAM 104606, (e) Stegonotus guentheri AM 129712, (f) Stegonotus heterurus BPBM 22556, (g) Stegonotus cucullatus LSUMZ 94371. Photos from SR. (h) Stegonotus modestus LSUMZ 92339, (i) Stegonotus iridis sp. nov. SJR 7514, (j) Stegonotus diehli LSUMZ 92344 (k) Stegonotus melanolabiatus sp. nov. AMS R115361 (l) Stegonotus derooijae sp. nov. SAMA R70467 (m) Stegonotus admiraltiensis sp. nov. LSUMZ 93597, (n) Stegonotus parvus LSUMZ 92333. Photos from Sara Ruane and Stephen J. Richards.

Figure 3. Map of New Guinea sampling localities for Stegonotus (a) and mtDNA + nucDNA maximum likelihood gene tree (b). Symbols for species/clades match those on the map; * indicates bootstrap values ≥ 70. For some localities, symbols were adjusted for better visibility and so localities are approximate; see Appendix 1. for exact locality information.

Figure 4. Photographs of three Stegonotus species described here in life; (a) Stegonotus iridis sp. nov. SAMA R70466 (b) Stegonotus derooijae sp. nov. MZB.Ophi.3288 (c) Stegonotus admiraltiensis sp. nov. from Manus Island, unregistered. Photos from Stephen J. Richards.

Figure 5. Photographs of holotype Stegonotus iridis sp. nov. MZB.Ophi.3306 showing (clockwise from top left) dorsal of body, ventral of body, dorsal of head, lateral of head. Photos from Stephen J. Richards.