Rhynchocalamus hejazicus Licata & Pola & Šmíd & Ibrahim & Liz & Santos & Patkó & Abdulkareem & Gonçalves & AlShammari & Busais & Egan & Ramalho & Smithson & Brito 2024, sp. nov.
Creators: name: Licata, Fulvio
name: Pola, Lukáš
name: Šmíd, Jiří
name: Ibrahim, Adel A.
name: Liz, André Vicente
name: Santos, Bárbara
name: Patkó, László
name: Abdulkareem, Ayman
name: Gonçalves, Duarte V.
name: AlShammari, Ahmed Mohajja
name: Busais, Salem
name: Egan, Damien M.
name: Ramalho, Ricardo M. O.
name: Smithson, Josh
name: Brito, José Carlos
Publisher: name: Zenodo
Year: 2024
Subjects: Biodiversity
Taxonomy
Animalia
Chordata
Reptilia
Squamata
Colubridae
Rhynchocalamus
Rhynchocalamus hejazicus

description: Rhynchocalamus hejazicus sp. nov.
Type material.
Holotype. RCU-URN - 93850 (sample code FLI 447; Fig. 3; Table 1). Adult male; Kingdom of Saudi Arabia, Medina Province, Shaaran Nature Reserve (26.85895 ° N, 38.30387 ° E), 1035 m asl.; collected by Fulvio Licata on May 24, 2023. MorphoBank accessions: M 902248 – M 902255.
Paratypes. RCU-URN - 94064 (sample code FLI 330; Fig. 3; Table 1), melanistic adult female collected by Fulvio Licata and Leili Khalatbari on May 11, 2023, KSA, Medina Province, Harrat Khaybar (25.60676 ° N, 39.96734 ° E), elevation 1616 m asl, MorphoBank accessions: M 902243 – M 902247; RCU-URN - 94065 (sample code JCB 222), juvenile male collected by José Carlos Brito on November 2, 2023, KSA, Medina Province, Jabal Al Ward (26.36263 ° N, 37.38780 ° E), elevation 1277 m asl, MorphoBank accessions: M 902256 – M 902261; NMP 76815 (sample code LP 760; Fig. 4; Table 1), juvenile male collected by Damien M. Egan and Lukáš Pola on April 22, 2022, KSA, Tabuk / Medina Provinces, Prince Mohammed bin Salman Royal Reserve, 26 km east of Al Qurr village (26.6028142 ° N, 37.1225145 ° E), elevation 781 m asl, MorphoBank accessions: M 902293 – M 902338; NMP 76816 (sample code JIR 551), adult, sex undetermined, collected by Ahmed Mohajja AlShammari and Mubarak Al – Aslami in July 2021, KSA, Hail Province, Jabal Salma, south of An Niayy village (27.165278 ° N, 42.294444 ° E), elevation 1052 m asl, MorphoBank accessions: M 902290 – M 902292; MNHN – RA – 2023.0013 (sample code JIR 544; Fig. 4; Table 1) adult female collected by Adel A. Ibrahim and Ahmed Mohajja AlShammari on May 11, 2017, KSA, Hail Province, Jabal Salma, Wadi Al – Azraq, east of Zekheen village (26.948889 ° N, 41.973889 ° E), elevation 1099 m asl, MorphoBank accessions: M 902262 – M 902289.
Other material.
Additional unvouchered individuals, assigned to this species based on phenotypical resemblance and unique head pattern, were encountered in May, June, and November 2023 by Vidak Lakušić, Gholam Hosein Yusefi, and Fulvio Licata in Harrat Uwayrid, Al-Gharameel, Wadi Nakhlah, and Sharaan (conservation areas located in the AlUla County, Medina Province). Other individuals were observed in July and August 2023 by Neil Rowntree and Euan Ferguson in NEOM, the northwestern region of Tabuk Province, KSA. One record was found in the public database iNaturalist (https://www.inaturalist.org/observations/20014261). Based on the provided information, the snake was recorded on February 1, 2019 at As Salam, Medina Province (24.464058 ° N, 39.537669 ° E). An additional individual was reported to us by Muteb Masad Al – Malki from the vicinity of Adham city (20.4486525 ° N, 40.8792636 ° E) from Mecca Province.
Etymology.
The species name is a latinized noun in masculine gender derived from the word " Hejaz – " = Hejaz Mountains, a mountain range located in the Hejaz region (an important region located in western Saudi Arabia, where the two holy cities of Islam, Mecca, and Medina are located) where most individuals were observed, and the Latin suffix " – icus " = “ belonging to ”. We suggest the common name “ Hejaz black – collared snake ” in English and أبو حناء [Abu Henna] in Arabic for the new species.
Diagnosis.
The new species of Rhynchocalamus from the Hejaz Mountain range in western Saudi Arabia is characterised by the following morphological characters: (1) SVL 209.2–339.5 mm in adults; (2) tail length 38.3–64.2 mm in adults; (3) loreal scale present; (4) large 3 rd and 4 th upper labial scales in contact with the eye; (5) one preocular scale; (6) 1–2 postocular scales; (7) one temporal scale; (8) 0–2 post – temporal scales; (9) six upper labial scales; (10) eight lower labial scales; (11) usually four lower labial scales in contact with the anterior inframaxillars; (12) usually one gular scale in contact with anterior inframaxillars, situated between the posterior inframaxillars; (13) 15 smooth dorsal scales at mid-body; (14) 11–12 dorsal and temporal scales surrounding the margin of parietals; (15) 227–250 ventrals; (16) anal and subcaudal scales divided; (17) 67–70 subcaudal scales; (18) dorsal colouration in life deep reddish with a distinctive black collar extending behind the parietal scales and abruptly stopping or tapering backward in the middle, and a pale reddish band passing behind the eyes, through the middle of the supraoculars and the frontal scale, encompassing the temporal and parietal scales.
Colouration in life (adults).
The upper surface of the head is shiny black from the middle of the supraoculars and the frontal scale to the tip of the snout, which is whitish; a wide band, pale reddish dorsally and fading to whitish ventrally, passes behind the eyes, through the middle of the supraoculars and the frontal scale, encompassing the temporal and parietal scales; a black collar around the neck reaches the ventrals, and abruptly stops or tapers dorsally towards the centre; dorsal surface of the body and tail uniformly deep reddish from the end of the collar to the tail tip; ventral surface of the body deep reddish fading to whitish in the upper part of the body, narrowing in correspondence of the black collar; colour pattern paler in alcohol preserved specimen. A melanistic morph, uniformly black, also occurs.
Comparison.
Rhynchocalamus hejazicus sp. nov. is morphologically similar to the other Rhynchocalamus species, and it can be distinguished by slight differences in size, colouration, and head and body scalation.
In comparison with R. arabicus, R. hejazicus sp. nov. has a lower number of subcaudal scales (67–70 vs. 71–81 in R. arabicus). We show that a melanistic morph of R. hejazicus sp. nov. also occurs, therefore the new species can be easily misidentified as R. arabicus.
Rhynchocalamus hejazicus sp. nov. differs from R. dayanae by smaller maximum body size (339.5 vs. 432.1 in R. dayanae), a shorter tail (38.3–64.2 vs. 59.2–94.1 in R. dayanae), by a higher number of ventrals (227–250 vs. 198–229 in R. dayanae) and subcaudals (67–70 vs. 54–62 in R. dayanae), Lastly, R. hejazicus sp. nov. can be further differentiated from R. dayanae by the presence of a pale reddish band passing between the eyes and the neck.
Rhynchocalamus hejazicus sp. nov. differs from R. melanocephalus (both Southern population from the Negev region in Israel and Northern population from the Mediterranean ecoregion; sensu Tamar et al. 2020) by a smaller maximum body size (339.5 vs. 499.2 in R. melanocephalus), a lower number of post-temporal scales (1 vs 2 in R. melanocephalus), a higher number of lower labial scales (8 vs. 7 in R. melanocephalus), a higher number of ventrals (227–250 vs. 164–235 in R. melanocephalus), and subcaudals (67–70 vs. 29–69 in R. melanocephalus). Lastly, R. hejazicus sp. nov. can be further differentiated from R. melanocephalus by a pale reddish band between the eyes and the neck.
Rhynchocalamus hejazicus sp. nov. differs from R. satunini in having a longer tail (64.2 vs. 54 mm in R. satunini), a higher number of ventrals (227–250 vs. 201–226 in R. satunini) and subcaudals (67–70 vs. 53–64 in R. satunini), and a lower number of upper labials (6 vs. 7 in R. satunini). Lastly, R. satunini is characterised by two black patches on a pale reddish / whitish background on the prefrontals and the parietals, and a black band around the neck that does not reach the ventrals.
In comparison with R. levitoni, R. hejazicus sp. nov. has a lower number of upper labials (6 vs. 7 in R. levitoni), and it can be distinguished by the overall different colouration (deep reddish vs. lemon yellow in R. levitoni), and the absence of a V-shaped band on the neck, and dark markings on the parietals.
Description of the holotype.
Adult male (voucher code RCU-URN - 93850) (Fig. 3). Snout-vent length 321.1 mm, tail length 63.6 mm. Body cylindrical and slender. The head is small and relatively narrow, slightly distinct from the neck. Head scales not keeled. Rostral scale elongated, extending backwards and wedged between the internasals, which are separated, and touching the bottom of the suture between the prefrontals. The rostral is bordered by two upper labials, two nasals, two internasals, and two prefrontals. Nostrils are situated on undivided nasal scales internasals of triangular shape, separated by the rostral scale. A trapezoid loreal scale at either side in contact with the 2 nd and 3 rd upper labials. The eyes are small, with circular pupils. One preocular scale on both sides. Two postocular scales on both sides. Bell-shaped frontal scale, located between the supraoculars and wedged between the parietals. Six squarish upper labials, the 3 rd and 4 th in contact with the eye. two large parietal scales; one temporal and one post – temporal scale on the left side, while on the right side, only one enlarged temporal is present. Eight lower labials. Four lower labials are in contact with anterior inframaxillars on each side. Two gular scales are positioned between the posterior inframaxillars and in connection with the anterior inframaxillars. Anterior inframaxillars are almost double in size than posterior inframaxillars. Eleven dorsal and temporal scales surround the posterior margin of the parietals. Fifteen dorsal scale rows at mid-body. 247 ventrals and 67 subcaudals, including a conical scale at the tail tip.
Known and potential distribution and habitat.
The known extent of occurrence (EOO) of R. hejazicus sp. nov. is more than 274,674 km 2 and the area of occurrence (AOO) is 56 km 2. The individual reported from the vicinity of Adham city (20.4486525 ° N, 40.8792636 ° E) from Mecca Province represents the southernmost record to our knowledge.
Available material and photographic records suggest that the species is scattered across Tabuk, Medina, Hail and Mecca Provinces, and is likely endemic to KSA. Nevertheless, it should be noted that additional range extensions of many overlooked species are now being reported with each herpetofaunal survey carried out in the unexplored regions of northwestern and western KSA (e. g., Aloufi et al. 2020, 2021, 2022; Pola et al. 2024), suggesting that the range of this rather secretive species could be even wider. Currently, the northwesternmost individual is reported from the area west of Jabal Al Lawz, approx. 70 km south of the Jordanian border. Given the presence of similar habitats harbouring many shared species, we cannot rule out the species occurrence in that area, especially in the mountains of Aqaba.
Rhynchocalamus hejazicus sp. nov. has been observed between 456 and 1610 m a. s. l., in the following habitats: (i) sandy flatland with sparse vegetation (Acacia sp., bushes, and tussock grasses; Fig. 5); (ii) large, stony wadis in lava fields (= harrat) with dense patches of woody vegetation (Acacia sp.; Fig. 5); (iii) sparsely vegetated rocky creek with temporary pools.
The species distribution models achieved good performance levels (AUC: 0.9–0.94; TSS: 0.78–0.87; Boyce Index: 0.42–0.99), resulting in an overall good predictive accuracy of the final ensemble models (Boyce index: 0.71). The potential distribution of R. hejazicus sp. nov. mostly includes the known range of the species, but other extralimital suitable areas are identified to the northwest (i. e., the Sinai Mountains in South Sinai, Aqaba mountains, and Wadi Rum in Jordan), and to the north (i. e., Jabal Tubaiq hills at the border with Jordan and Upper Galilee mountains in North Israel; Fig. 6). The main drivers of environmental suitability in our models were the altitude (26.7 % of explained variance) and the mean temperature of the wettest quarter (BIO 8; 15.6 %), suggesting that R. hejazicus sp. nov. is associated with altitudes above 1,000 m a. s. l., in regions characterised by cold wet months (<20 ° C). Furthermore, the precipitation of the warmest quarter (BIO 18; 13.5 %) and the precipitation seasonality (BIO 15; 13 %) were also related to the probability of occurrence of the species, indicating that the species is likely to occur in areas with relatively dry hot months (precipitations <50 mm) and stable rainfall regimes.
Natural history.
Little is known about the species’ natural history and behaviour. Although the current number of observations is limited, it appears that R. hejazicus sp. nov. has mainly nocturnal activity as all individuals were encountered active at night. We assume that in many biological aspects, it will be concordant with its congeners (Amr and Disi 2011; Tamar et al. 2016; Torki 2017; Fathinia et al. 2017).
Other reptile species observed in syntopy of the NMP 76815 (LP 760) were Ptyodactylus cf. hasselquistii (Phyllodactylidae), Pristurus guweirensis (Sphaerodactylidae), and Echis coloratus (Viperidae). In Hail Province, at Jabal Salma range, Echis coloratus, Cerastes gasperettii (Viperidae) and Walterinnesia aegyptia (Elapidae) were found in sympatry (Alshammari and Ibrahim 2015; Alshammari et al. 2017). In AlUla County, it was found in sympatry with Ptyodactylus guttatus (in prep.), Ptyodactylus cf. hasselquistii, Bunopus tuberculatus, Hemidactylus granosus, Stenodactylus doriae, Stenodactylus slevini, Tropiocolotes yomtovi (the latter five all Gekkonidae), and Echis coloratus.
Conservation status.
We propose to classify R. hejazicus sp. nov. as Least Concern, based on the wide EOO, and the diverse and continuous habitats where the species is encountered, including habitats with heavy anthropogenic disturbance (e. g., overgrazing) and urban habitats (see https://www.inaturalist.org/observations/20014261). Although R. hejazicus sp. nov. is at the moment known from 14 localities and its AOO is only 56 km 2, we consider it premature to classify it as Near Threatened as the limited number of localities could reflect the generally undersampled distribution and secretive habits of the species. Furthermore, six of the known localities occur within conservation areas located in AlUla County (Medina Province), where protection measures have been implemented.
description: Published as part of Licata, Fulvio, Pola, Lukáš, Šmíd, Jiří, Ibrahim, Adel A., Liz, André Vicente, Santos, Bárbara, Patkó, László, Abdulkareem, Ayman, Gonçalves, Duarte V., AlShammari, Ahmed Mohajja, Busais, Salem, Egan, Damien M., Ramalho, Ricardo M. O., Smithson, Josh & Brito, José Carlos, 2024, The missing piece of the puzzle: A new and widespread species of the genus Rhynchocalamus Günther, 1864 (Squamata, Colubridae) from the Arabian Peninsula, pp. 691-704 in Zoosystematics and Evolution 100 (2) on pages 691-704, DOI: 10.3897/zse.100.123441