Zootaxa 3755 (1): 096–100 www.mapress.com /zootaxa / Copyright © 2014 Magnolia Press
ISSN 1175-5326 (print edition)
Correspondence
ZOOTAXA
ISSN 1175-5334 (online edition)
http://dx.doi.org/10.11646/zootaxa.3755.1.5 http://zoobank.org/urn:lsid:zoobank.org:pub:FF54C117-9567-48D8-B617-3798D5B48383
New data on the morphology and distribution of the enigmatic Schouteden’s sun snake, Helophis schoutedeni (de Witte, 1922) from the Congo Basin ZOLTÁN T. NAGY1,7, VÁCLAV GVOŽDÍK2,3, DANNY MEIRTE4, MARCEL COLLET5 & OLIVIER S.G. PAUWELS6 1
Royal Belgian Institute of Natural Sciences, Joint Experimental Molecular Unit, Rue Vautier 29, 1000 Brussels, Belgium. E-mail:
[email protected] 2 Institute of Vertebrate Biology, Academy of Sciences of the Czech Republic, Květná 8, 603 65 Brno, Czech Republic 3 National Museum, Department of Zoology, Cirkusová 1740, 193 00 Prague, Czech Republic 4 Royal Museum for Central Africa, Leuvensesteenweg 13, 3080 Tervuren, Belgium 5 Parc Marin des Mangroves, Muanda, Democratic Republic of the Congo 6 Royal Belgian Institute of Natural Sciences, Rue Vautier 29, 1000 Brussels, Belgium 7 Corresponding author
The Schouteden’s sun snake is the sole representative of its genus, and was originally described by the Belgian herpetologist Gaston-François de Witte as a colubrid, Pelophis schoutedeni (de Witte 1922). Twenty years later, the new generic name Helophis was established by de Witte & Laurent (1942) because the generic name Pelophis was preoccupied by Pelophis Fitzinger, 1843 [type species: Brachyorrhos (now Enhydris) alternans Reuss, 1834]. De Witte (1922) and de Witte & Laurent (1942) gave data on two syntypes (Fig. 1), which are preserved in the herpetological collection of the Royal Museum for Central Africa in Tervuren, Belgium. One, RMCA R.2468, was found in Tondu (at Lac Tumba, Équateur Province, Democratic Republic of the Congo = DRC), while the other, RMCA R.2469, was collected in Kwamouth (“Moyen-Congo”, now Bandundu Province, DRC). Both were collected by Henri Schouteden in 1921. In the original description, no information was given about the sex of the syntypes. De Witte & Laurent (1942) reported a third specimen (RMCA R.11551) from Léopoldville (today Kinshasa), which was collected in 1937 by Henrard. Since then, this snake species was almost forgotten, and the genus has remained monotypic. To our knowledge, no photographs of living specimens of this species have been published so far. In general, very little is known about the distribution, biology, conservation status or even the phylogenetic relationships of this vividly colored snake species. Although several works listed Helophis schoutedeni as being part of the Congo Basin (DRC) snake fauna (e.g. Kusamba 1990; Meirte 1992; Trape & Roux-Estève 1995; Broadley 1998) sometimes including a basic identification key, no new information was given. Moreover, no recent field guides of the Central African region (e.g., Chippaux 2006) include this snake species. Regarding its classification, Broadley (1998) considered it as a natricine species (Natricinae) while in The Reptile Database (Uetz & Hošek 2013) it is listed as Colubridae incertae sedis, similarly like in Pyron et al. (2013), where Helophis was missing from their phylogenetic meta-analysis. During a field expedition to the DRC in June–July 2012, we obtained a single specimen of this snake in Kinshasa, in the proximity of the Congo River. When handled, it behaved calmly and did not display any clear antipredatory behavior, just tried to escape by crawling off. We were able to take photographs (Fig. 2) and investigate scalation. The specimen is now in the collection of Marcel Collet. Herein we present a morphological description of this specimen, which will add relevant and new information to the original description and diagnosis of the species [in brackets we give the information as is in the original description]. Body stout, cylindrical, head barely distinct from neck. Tail short, cylindrical, progressively tapering to a pointed tip. Eye small, pupil round. Rostral small, rounded, wider than high, narrowly visible from above. Two internasals, rightangled triangular, very narrow. Suture between the internasals slightly lower than suture between prefrontals. Prefrontals wider than long. Frontal distinctly longer than wide, slightly longer than its distance from the snout tip and slightly shorter than the suture between parietals. Parietals long and wide, shorter than their combined width. Nasals divided into pre- and postnasal, the prenasal longer than the postnasal. Nostrils directed upwards, located on the suture between preand postnasal. Supralabials 11/11 [10–11 in syntypes], 9th and 10th largest; on each side 6th and 7th supralabials in contact with orbit [5th and 6th as well as 6th and 7th in syntypes]. Loreals 1/1, longer than high. Left loreal surrounded by postnasal,
96 Accepted by S. Carranza: 16 Dec. 2013; published: 20 Jan. 2014
FIGURE 1. Photos of the syntypes of Helophis schoutedeni. Top: RMCA R.2468 from Tondu, bottom: RMCA R.2469 from Kwamouth.
NEW DATA ON HELOPHIS SCHOUTEDENI
Zootaxa 3755 (1) © 2014 Magnolia Press ·
97
FIGURE 2. Photos of a living specimen of Helophis schoutedeni, found in 2012 in Kinshasa. From top left, clockwise: dorsal view of the specimen; ventral view of the specimen; dorsolateral view of the forepart of the animal; ventral view of the head.
FIGURE 3. Map of the central Congo Basin with distribution records of Helophis schoutedeni based on voucher specimens deposited in RMCA and the new record. Stars refer to the type localities, circle with black dot to the new record and yellow shading to approximate distribution of the Eastern Congolian swamp forests according to the World Wildlife Fund (2012).
supranasals 2–5, preocular and prefrontal. Right loreal surrounded by postnasal, supralabials 3–5, preocular and prefrontal. Preoculars 1/1, much higher than broad and much higher than eye. On the left side, preocular in contact with the frontal by a point; on the right side, preocular separated from the frontal by the supraocular. No suboculars. Supraoculars 1/1, much narrower than frontal. Postoculars 2/2, the upper one much larger than the lower one. Temporals
98
· Zootaxa 3755 (1) © 2014 Magnolia Press
NAGY ET AL.
1 + 2 + 4 / 1/(1 + 1) + 3 + 4. Infralabials 11/11, first pair in broad contact behind the mental. Two pairs of sublinguals. On the left side, the anterior sublingual is fused with the posterior one. On the right side, five infralabials contact the anterior sublingual [like in the specimen collected in 1937 but contrary to the syntypes, where four infralabials contact the sublinguals]. The vertebral row is not enlarged. All head, dorsal and ventral scales smooth [dorsal very weakly keeled in syntypes]. Two preventrals + 155 ventrals [163–166 in syntypes]. There are three additional half ventrals: on the right side between ventrals 147 and 148, on the left side between ventrals 148 and 149, and on the left side between the last ventral (155th) and the anal, none of them included in the number of ventrals. Anal plate divided. Subcaudals 46 (excluding terminal pointed scale), divided [45–48 in syntypes, in one of the two specimens the six anterior subcaudals are undivided]. The maxillary teeth are arranged in a continuous series without diastema; the most posterior maxillary teeth are enlarged (opisthodont), however we lack information if grooved or not, positioned more facially, outside the row of the other maxillary teeth. Coloration in life: Dorsum black with more than 80 dark orange rings. These rings are one to two dorsals long, and are separated by one or two black dorsal scales. The rings become more irregular and less clear in the posterior part of body. They do not encircle the body; their base at the lower part of the flanks often bifurcates. The ventrum is black with irregularly distributed orange spots, mostly in the posterior part of ventrals. The posterior part of the ventrum is uniformly black, as is the underside of the tail. The dorsal surface of the head is dark orange, with black markings along the scale sutures. The anterior part of each supralabial, infralabial and gular is black. The posterior part of the anterior ventrals on throat is orangish white, their anterior part is black. The round pupil is black, the iris is uniformly dark orange, of the same color as the majority of the head surface and dorsal rings. The inside part of the mouth is pink. Although this species was never reported since the publication of de Witte & Laurent (1942), we discovered that the herpetological collection of the Royal Museum for Central Africa (RMCA) holds four further specimens collected in the 1950s–1960s and 32 additional specimens collected in the 1980s (see Appendix). None of these additional specimens have been reported before, consequently no data of those were made available so far. Here we summarize the distribution data based on these specimens from the DRC (Fig. 3), with a majority originating from the Eastern Congolian swamp forest ecoregion as defined by the World Wildlife Fund (2012). Considering these additional specimens, now we have a much detailed information also about character variation in Helophis schoutedeni. Herein we present an overview of basic morphological characters. Maximal snout-vent length: 482 mm (males), 655 mm (females); maximal tail length: 100 mm (males), 102 mm (females); 22–23 rows of dorsal scales at midbody (median 23); ventrals 153–180 (males), 156–169 (females); subcaudals 38–59 (males), 36–46 (females); anal plate and subcaudals always divided; 10–12 supralabials, 5+6, 6+7 or 5+6+7 in contact with the eye; typically 1/1 preocular (very rarely 2) and 2/2 postoculars (rarely 1 and in a single specimen 3/3). In addition, we were able to determine the sex of both syntypes using X-ray radiography. Both specimens (RMCA R.2468 and RMCA R.2469) are apparently males.
Discussion Since the majority of distribution records are coming from the Eastern Congolian swamp forests upriver the Congo River and its tributaries, it opens a question about the origin of the specimens collected in Léopoldville/Kinshasa. The strong current of the Congo River often carries floating vegetation islands, which occasionally introduce fauna and flora from the upriver into the Lower Congo region (MC, pers. observ.). This phenomenon might also explain the findings of the Schouteden’s sun snake outside the swamp forests. Ecologically, Helophis schoutedeni is obviously a semi-aquatic snake as indicated by its dorsally-oriented nostrils, narrow triangular internasals, small eyes with round pupil and stout body. Furthermore, during a short period in captivity, the observed Schouteden’s sun snake preferred to stay in water. Helophis shows an extreme similarity to the genus Hydraethiops, as de Witte (1922) indicated in the original description. He, however, also mentioned that two differences between them, i.e., the double internasals and the lower number of teeth in Helophis, justified the erection of a new genus. Boulenger (1904), in his description of Hydraethiops laevis, indicated, based on the observations that he made on the two syntypes, that the internasals could be divided or semi-divided. The third known individual of Hydraethiops laevis, from the Chaillu Massif in Gabon, shows a single internasal (Pauwels et al. 2002). The condition of the internasals is variable in Hydraethiops melanogaster as well; for example, the individual illustrated by de Witte (1962) shows a partly divided internasal. Helophis shows 16 or 17 maxillary teeth (de Witte 1922; Meirte 1992), while Hydraethiops shows 20 to 22 (Chippaux 2006). The internasals’ condition in Helophis is thus not a character separating it from Hydraethiops. The slightly lower number in maxillary teeth does not justify alone the placement in a distinct genus. Pending a genetic analysis, the genus Helophis could be regarded as valid while doubtful with regard to Hydraethiops, but at least its placement within Natricinae along with Hydraethiops as proposed by Broadley (1998) seems justified on a morphological basis. NEW DATA ON HELOPHIS SCHOUTEDENI
Zootaxa 3755 (1) © 2014 Magnolia Press ·
99
Acknowledgements This project run with the financial support from the Belgian Directorate General for Development Cooperation, Global Taxonomy Initiative (grant holder: ZTN). VG would like to acknowledge the financial support of the European Commission’s Research Infrastructure Action (the SYNTHESYS Project No. BE-TAF-3076) and Ministry of Culture of the Czech Republic (DKRVO 2013/14, National Museum, 00023272). We appreciate the constructive comments of two anonymous reviewers.
References Boulenger, G.A. (1904) Descriptions of three new snakes. Annals and Magazine of Natural History, 7, 450–452. Broadley, D.G. (1998) The reptilian fauna of the Democratic Republic of the Congo (Congo-Kinshasa). In: Schmidt, K.P. & Noble, G.K. (Eds.), Contributions to the Herpetology of the Belgian Congo. [reprint of the 1919 and 1923 papers]. SSAR Facsimile reprints in Herpetology, 780 pp. Chippaux, J.-P. (2006) Les serpents d’Afrique occidentale et centrale. IRD Editions, Collection Faune et Flore tropicales, 35, Paris, 311 pp. Fitzinger, L. (1843) Systema reptilium. Fasciculus primus, Amblyglossae. Vindobonae, Braumüller & Seidel, 106 + VI pp. Kusamba, C. (1990) Snakes of Zaire and their bites. African Study Monographs, 10, 137–157. Meirte, D. (1992) Clés de détermination des serpents d’Afrique. Annales du Musée royal de l’Afrique centrale (Sciences Zoologiques), 267, 1–152. Pauwels, O.S.G., Kamdem Toham, A. & Chimsunchart, C. (2002) Recherches sur l’herpétofaune du Massif du Chaillu, Gabon. Bulletin de l’Institut Royal des Sciences naturelles de Belgique, 72, 47–57. Pyron, R.A., Burbrink, F.T. & Wiens, J.J. (2013) A phylogeny and revised classification of Squamata, including 4161 species of lizards and snakes. BMC Evolutionary Biology, 13, 93. http://dx.doi.org/10.1186/1471-2148-13-93 Trape, J.F. & Roux-Estève, R. (1995) Les Serpents du Congo: Liste commentée et clé de détermination. Journal of African Zoology, 109, 31–50. Uetz, P. & Hošek, J. (Eds.) (2013) The Reptile Database. Available from: http://www.reptile-database.org (accessed 14 October 2013) Witte, G.-F. de (1922) Description d'un ophidien nouveau récolté au Congo par le Dr. Schouteden. Revue de Zoologie Africaine, 10, 318–319. Witte, G.-F. de (1962) Genera des serpents du Congo et du Ruanda-Urundi. Annales Sciences Zoologiques, Musée Royal de l’Afrique Centrale, 104, VIII+ 203 pp. + XV pl. Witte, G.F. de & Laurent, R. (1942) Contribution à la faune herpétologique du Congo belge. Revue de Zoologie et Botanique africaines, 36, 101–115. World Wildlife Fund (2012) Eastern Congolian swamp forests. The Encyclopedia of Earth. Available from: http:// www.eoearth.org/view/article/151901 (accessed 30 October 2013)
APPENDIX List of additional specimens (all from the Democratic Republic of the Congo) deposited in the herpetological collection of the RMCA, grouped by locality (see also Fig. 3): Bamania: RMCA R.16676; Boende: RMCA R.29324; Bokoro: RMCA R.16490; Boteka: RMCA 83-24-R-38, RMCA 83-24-R-39, RMCA 83-24-R-40, RMCA 83-24-R-41, RMCA 83-24-R-104, RMCA 8324-R-105, RMCA 83-24-R-106, RMCA 83-24-R-107, RMCA 83-24-R-108, RMCA 83-24-R-109, RMCA 83-24-R-110, RMCA 83-24-R-111, RMCA 83-24-R-112, RMCA 83-24-R-113, RMCA 83-24-R-114, RMCA 83-24-R-115, RMCA 83-24-R116, RMCA 83-24-R-117, RMCA 83-24-R-118, RMCA 84-25-R-33, RMCA 84-25-R-34, RMCA 84-25-R-35, RMCA 85-21R-20, RMCA 85-30-R-22; Bumba: RMCA R.19578; Wafanya: RMCA 88-33-R-96, RMCA 88-33-R-97, RMCA 88-33-R-98, RMCA 88-33-R-99, RMCA 89-20-R-83, RMCA 8920-R-84, RMCA 89-20-R-85, RMCA 89-20-R-150.
100
· Zootaxa 3755 (1) © 2014 Magnolia Press
NAGY ET AL.
