Evolution of coloration, urotomy and coral snake mimicry in the snake genus Scaphiodontophis (Serpentes: Colubridae)

The Neotropical hinged-tooth, coral snake mimics of the genus Scaphiodontophis are characterized by extremely long and disproportionately thick tails that are extremely fragile. Both the coloration and tail structure are putative antipredator devices. While all examples have components of the coloration that match those of the venomous coral snakes (family Elapidae), the range of variation is extreme, leading to controversy on the status of various populations, including nine named taxa. Individual, ontogenetic and geographic variation in scutellation and head, body and tail coloration were analysed to evaluate population status and possible evolutionary trends based on a sample of 183 examples from Mexico, Central America and Colombia. Variation in subcaudal counts show population differences (higher in Mexico and upper Central America) but are not congruent with geographic variation in coloration. Generally snakes from north of Nicaragua and from central and eastern Panama have a pattern of dyads (black-light-black bands separating red bands), those from Atlantic slope Nicaragua to western Panama a pattern of monads (light-black-light bands separating the red ones) and those from Colombia have both pattern types on the same snake. The dyads and/or monads may be present the length of the body and tail, restricted to the anterior part of the body or on the entire body or on the anterior part of the body and on the tail. Two or more of these variants may occur at a single geographic locality or only a single one may be present. Head and nuchal colour patterns (Z, A, V and Du) are relatively consistent geographically. The Adantic slope Guatemala, Belize and Honduras population have the A pattern, those of Nicaragua, Costa Rica and western Panama the V pattern, and those in Colombia a Du pattern. Other populations have the Z coloration. Intermediate conditions in coloration of the body and tail and head and neck are found at localities intermediate between the main pattern types, indicating intergradation among adjacent populations. Consequently, we regard these snakes as representative of a single species, Scaphiodontophis annulatus Dumeril and Bibron and the eight other names applied to various populations and individuals as synonyms. Analysis of colour pattern leads us to the conclusion that the tricolour pattern evolved from a uniform one through a lineate-spotted condition (usually present on the non-tricolour portions of the snake) through a bicolour red and black pattern to the dyadal condition. The monadal pattern in turn was derived from the dyadal one. The data further indicates that tricolour components first appeared anteriorly and progressively expanded posteriorly. The evolutionary sequence for the head and nuchal pattern appears to be A → Z → V → Du S. annulatus has a series of jaw and tooth specializations designed for rapid processing of hard-bodied prey found during diurnal foraging in the leaf-litter. Urotomy in this species involves intervertebral tail-breakage (pseudoautotomy) without regeneration. Evidence is presented supporting the long-tail multiple break hypothesis as applicable to Scaphiodontophis and other snakes with similar tail morphology (specialized pseudoautotomy). This is in contrast to snakes with similar tail morphology (specialized pseudoautotomy). This is in contrast to Coniophanes and other snakes with a high incidence of urotomy having long but unspecialized tails (unspecialized pseudoautotomy) without multiple breaks over time. All Scaphiodontophis colour patterns have a general resemblance to that of venomous coral snakes and offer protection from generalizing predators having innate or other triggered responses to coral snake colours. The aposematic effect is enhanced by tail thrashing and head twitching behaviours. The characteristic foraging pose of S. annulatus, which tends to expose the head and anterior body, makes even the incomplete tricolour pattern effective as an antipredator defence. No evidence supports the idea that tail thrashing or the incomplete tricolour pattern directs the predator attacks to the tail to expedite pseudoautotomy. Coral snake mimicry and specialized pseudoautotomy are shown not to be co-evolved and pseudautotomy seems to have evolved long before mimetic coloration in this genus.     

Coccidian parasites (Apicomplexa: Eimeriidae) of the endemic Florida snake Tantilla relicta Telford (Serpentes: Colubridae)

The endemic Florida snake Tantilla relicta Telford is parasitised by six species of coccidia. Caryospora tantillae n. sp. has nearly spherical oöcysts, 19.6 × 18.9 µm (16–22 × 16–21), with no polar body, and an oöcyst length/width ratio (shape index, SI) of 1.04 (1.00–1.11). Ovoidal sporocysts are 15.1 × 11.6 µm (12–17 × 10–13), with an SI of 1.30 (1.1–1.6), a single prominent Stieda body and a sporocyst residuum. Sporozoites are 14 × 2.5 µm. Caryospora relictae n. sp. also has nearly spherical oöcysts, 18.5 × 17.6 µm (16–22 × 15–20), but is distinguished by having a distinct polar body and a substieda body in sporocysts. The oöcyst SI is 1.05 (1.0–1.2). Sporocysts are ovoidal, 14.8 × 11.4 µm (12–17 × 10–16), with an SI of 1.29 (1.1–1.5) and a sporocyst residuum. Sporozoites are 10–14 × 2–2.5 µm. Isospora cf. wilsoni has ovoidal to spherical oöcysts without a micropyle, measure 17.4 × 17.1 µm (15–19 × 15–19), and have an SI of 1.02 (1.00–1.07). Oöcysts have no polar granule or oöcyst residuum. Sporocysts are ovoidal, 11.4 × 8.2 µm (9–14 × 7–10), with an SI of 1.39 (1.18–1.62). Both a Stieda body and sporocyst residuum are present, but a substieda body, characteristic of I. wilsoni as described, was not observed. Sporozoites are 7–8 × 2.5–3 µm. An Eimeria sp., of which the sample was too small to justify taxonomic designation, has nearly spherical oöcysts without micropyle, a size of 22.5 × 20.9 µm (22–23 × 20–22), an SI of 1.08 (1.00–1.12) and no polar granule. Sporocysts measure 12.5 × 8.9 µm (11–14 × 7–11) and have an SI of 1.44 (1.18–1.87), a sporocyst residuum and no Stieda body. Sporozoites are 13 × 5 µm. Eimeria amphorae n. sp. has ovoidal to spherical oöcysts without a micropyle, a size of 24.8 × 22.3 µm (23–27 × 20–26), an SI of 1.12 (1.02–1.25) and no polar granule or oöcyst residuum. Sporocysts are elongate, 18.4 X 8.0 µm (17-22 × 6-9.5), with an SI 2.33 (1.79–3.00) and no discernible Stieda body or sporocyst residuum. Sporocyst shape differs by orientation, rectangular to amphora-like, tapering abruptly to a blunt point; sporozoites large, 15.5 × 4.2 µm. A biliary parasite, Eimeria pleistocenensis n. sp., has ovoidal to elongate oöcysts, without micropyle, with a size of 27.8 × 19.4 µm (23–32 × 14–23), with an SI of 1.44 (1.17–1.82) and an oöcyst residuum but no polar granule. Sporocysts ovoidal, 10.7 × 8.6 (9–13 × 8–10), with an SI of 1.24 (1.05–1.37), a sporocyst residuum, but without Stieda body; sporozoites 8.8 × 2.7 µm. Similar oöcysts from other Tantilla relicta populations, T. relicta neilli in north Florida T. relicta pamlica in southeastern Florida and T. relicta relicta in south-central Florida, have dimensions that lie within the range of variation in the type population and identically shaped sporocysts that suggest conspecificity with E. pleistocenensis, and presence of the species in the precursor to Tantilla relicta prior to the second interglacial period.     

Understanding the formation of ancient intertropical disjunct distributions using Asian and Neotropical hinged-teeth snakes (Sibynophis and Scaphiodontophis: Serpentes: Colubridae)

Numerous taxa show ancient intertropical disjunct distributions. Many can be explained by well-known processes of historical vicariance, such as the breakup of Gondwanaland. Others, such as Asian–Neotropical divergences are not as well understood. To clarify the phylogenetic position and understand biogeographic and temporal origins of the geographically disjunct and morphologically unique genera of hinged-teeth snakes, Scaphiodontophis (n = 1) and Sibynophis (n = 9; Colubridae), we inferred a time-calibrated phylogeny with additional 107 taxa representing the superfamily Colubroidea using four genes (c-mos, cyt-b, ND2, RAG-1; 3085 bp). We used this tree to estimate ancestral areas for the group. The results show that Scaphiodontophis is sister to Sibynophis, both originated in the late Eocene/Oligocene in Asia and likely dispersed through Beringia to the New World, but unlike other snake groups left no extant species in temperate North America. Current recognition of Scaphiodontophiinae renders Colubrinae paraphyletic, and we resurrect the previously named subfamily Sibynophiinae to encompass both genera and use the tribes Sibynophiini (Sibynophis) and Scaphiodontophiini (Scaphiodontophis) to highlight the geographically distinct areas occupied by these taxa. These results suggest that intercontinental dispersal with extinction in intermediate areas can explain puzzling patterns of ancient intertropical disjunct distributions.     

Complete mitochondrial genome of the black-headed snake Sibynophis collaris (Squamata, Serpentes, Colubridae)

The black-headed snake Sibynophis collaris (Reptilia, Squamata, Colubridae) is a least concern species in the world. Two universal and two specific polymerase chain reaction (PCR) primers were used for long PCRs to amplify the whole mitochondrial genome of S. collaris. The products were subjected to do sequencing reactions. The complete genome is 17,163 bp in size, containing 37 genes coding for 13 proteins, 2 rRNAs, 22 tRNAs, and 2 control regions (CRI and CRII). The results could play an important role in the preservation of genetic resources for helping conservation of the endangered species.     

A new species of snake of the genus Sibon (Serpentes: Colubridae) of the Caribbean slope of Costa Rica

Sibon lamari, a new species of colubrid snake from northeastern Costa Rica is described on the basis of six specimens. The new form differs from the closely allied S. annulatus in color pattern, head size, subcaudal count, and number of labials bordering eye-orbit. This is the third species of Sibon, together with S. argus and S. longifrenis, possessing a green dorsal ground color in Costa Rica. Sibon lamari coexists sympatrically with S. annulatus, S. argus. S. longifrenis and S. nebulatus at the locality of Guayacán de Siquirres (Limón Province).     

Distribution and Variation in the Treeboa Corallus annulatus (Serpentes: Boidae)

The arboreal boid Corallus annulatus has a disjunct distribution in tropical wet forests from extreme southeastern Guatemala to southwestern Ecuador (west of the Andes). The characters upon which subspecies (C. a. blombergi and C. a. colombianus) were described are shown to be of no diagnostic value. Based on a suite of characters (scale, pattern, osteological), Corallus a. blombergi is elevated to species status and Corallus a. colombianus is placed in the synonymy of C. annulatus. Corallus annulatus and C. blombergi are considered to be species that are genuinely uncommon, although not necessarily rare. Resumen La boa arbórea Corallus annulatus tiene una distribución alopatrica en bosques húmedos tropicales desde el extremo sudeste de Guatemala hasta el sudoeste de Ecuador (oeste de los Andes). Demostramos que los carácteres usados para describir las subespecies C. a. blombergi y C. a. colombianus no tienen valor diagnóstico. Basado en carácteres de escamas, patrones, y osteológicos, Corallus a. blombergi es elevado al nivel de especie y Corallus a. colombianus es puesto en sinonimia con C. annulatus. Corallus annulatus y Corallus blombergi son consideradas como especies no verdaderamente comunes, pero no son necesariamente raras.     

Molecular phylogeography of the viperine snake Natrix maura (Serpentes: Colubridae): Evidence for strong intraspecific differentiation

The molecular phylogeography of the viperine snake, Natrix maura (Linnaeus, 1758), was investigated using complete sequences of the mitochondrial cytochrome b gene and genomic ISSR-PCR fingerprinting. In a total of 120 samples, 44 unique cytochrome b haplotypes were found which defined three major genetic lineages associated with samples from Morocco, Tunisia and Europe, respectively. The same lineages were supported by nuclear data. A possible fourth lineage exists in southern Spain. Genetic distances of cytochrome b sequences between the three main lineages were in the range of 3.9–5.6%, suggesting independent evolution since the early Pliocene. Distinction of the three major lineages at the subspecies or species level is discussed to account taxonomically for the high intraspecific variation in the viperine snake. A more detailed analysis of the European samples based on genetic diversity indices and a network reconstruction suggests a complex Pleistocene history for the viperine snake in Europe. Clear differentiation was found between populations south and north of the central Iberian mountain ranges, suggesting Pleistocene glacial refugia both in the southern and northern Iberian peninsula. In the south, genetic diversity was associated with the main river valleys, whereas northern haplotypes were more broadly distributed, indicating gene flow or postglacial range expansions. Unexpectedly high levels of genetic variation in southeastern France and northwestern Italy would be compatible with the hypothesis of a glacial refugium north of the Pyrenees or in Italy. However, due to the dependence of N. maura on warm climates, the assumption of a northern refugium seems unwarranted. We believe that further sampling in northern Spain is likely to reveal genetically diverse populations which could have served as sources for postglacial recolonization of France and Italy.     

Hepatozoon species (Apicomplexa: Hepatozoidae) of the corn snake,Elaphe guttata (Serpentes: Colubridae) and the pigmy rattlesnake,Sistrurus miliarius barbouri (Serpentes: Viperidae) in south Florida

Hepatozoon guttata n. sp. is described from the corn snake (Elaphe guttata guttata) from south Florida. Gamonts average 14.6 x 4.6 (13-17 x 3.5-6) and are not recurved, with nucleus situated in the second quarter of the gamont. Erythrocyte cytoplasm rarely appears partially dehemoglobinized. The infected cells are usually distorted and are longer than the uninfected erythrocytes but do not differ in width; nuclei are smaller in length and width than those of uninfected cells. Sporogony in Aedes aegypti occurs within the head and the thorax but rarely in the abdomen. Oocysts are spherical to usually ovoid, 87.2 x 75.9 (45-155 x 40-152.5) and contain on average 7.1 (2-32) sporocysts. Sporocysts are spherical to ovoid, 34.8 x 31.0 (20-55 x 17.5-47.5), with 45.7 (14-89) sporozoites contained within. The pigmy rattlesnake (Sistrurus miliarius barbouri) in south Florida is parasitized by H. sistruri n. sp. Gamonts average 14.1 x 5.6 (12.6-15.8 x 4.7-6.3) in breadth and are not recurved, with the nucleus always situated in the second quarter of the gamont commonly at the midbody. Erythrocyte cytoplasm is not dehemoglobinized. The infected cells are always distorted and similar in length to the uninfected cells but with greater width and enlarged nuclei. Sporogony in A. aegypti occurs within head, thorax, and abdomen. Oocysts are spherical to usually ovoid, 163.6 x 154.7 (92-245 x 82-240) and contain 27.4 (12-42) sporocysts. Sporocysts are round to usually ovoid, 39.7 x 33.5 (25-50 x 20-50), with 45.7 (19-70) sporozoites.     

Evolution and phylogeny of the genus Natrix (Serpentes: Colubridae)

Some aspects of the natural history of snakes of the colubrid genus Natrix have been well studied. With their extensive European distribution and relative abundance, their ecology, reproduction and behaviour are well known. Yet other facets of their biology remain poorly understood. These include knowledge of Natrix phylogeny, hypotheses explaining the current distribution of the three extant members of the genus, and their evolution and relationships. In this study we used molecular data, the nucleotide sequences of four protein-coding mitochondrial genes (3806 bp total), to provide a well-supported phylogeny for the genus Natrix . With these molecular data, evidence from the fossil record, and knowledge of palaeogeological events, we used two approaches in designing a time scale which we used to date the major events in Natrix speciation and intraspecific variation. Our data strongly support a phylogeny for the genus in which N. maura is basal with N. natrix and N. tessellata being sister species. The calibrated molecular clock suggests that N. maura diverged from the common ancestor of the three species 18–27 mya and that N. natrix and N. tessellata diverged 13–22 mya. Although the ranges of these estimates are large they support an early Miocene to late Oligocene origin for the three species. Intraspecific divergence is estimated to have commenced 5.3, 6.0 and 6.7 mya with evolutionary rates of 1 : 1.25 : 1.35% per million years for N. maura, N. natrix and N. tessellata , respectively.  © 2006 The Linnean Society of London, Biological Journal of the Linnean Society , 2006, 87 , 127–143.     

Sense-organ-like parietal pits found in Psammophiini (Serpentes,Colubridae)

In several psammophine snake species, small sense-organ-like pits have been discovered occurring on the top of the head. These pits show a heretofore non-described structure. In numbers of one to four per head, they are present in Dromophis lineatus, Malpolon monspessulanus, several Psammophis species and Rhamphiophis rubropunctatus, but not in all individuals which is unrelated to sex. The reason for their sporadic occurrence remains obscure. Their equally obscure function is discussed in relation to the presumed functions of already known upper-head 'pits' in snakes. A histological study is in preparation.     

温泉蛇属Thermophis一新种——四川温泉蛇

From 2004 to 2006, several field trips in western Sichuan, China were carried out. A number of Thermophis snakes were collected in Litang County. After detailed morphological studies, we found that these Thermophis specimens were much different from those from Xizang (Tibet). We believed that Litang snakes should be a new species and describe it as below.     

莽山后棱蛇Opisthotropis cheni Zhao, 1999的再描述(Serpentes:Colubridae)

作者于1999年根据湖南宦章莽山标本发表新种莽山后棱蛇Opisthotropis cheni的鉴别特征,现对该蛇加以详细描述。莽山后棱蛇足小形水栖蛇,全长500～600mm,尾长占全长的五分之一左右,身体圆柱形,头较小,与颈区分不明显。鼻间鳞前端窄,鼻孔背侧位;眼小,背侧位;前额鳞单枚,甚宽,其两外侧扩展至头侧;颊鳞长,后端人眶;无眶前鳞,眶后鳞2;颞鳞1＋2（1）;上唇鳞8（3-2-3）为主;下唇鳞10,前4或5枚接前颔片;颔片2对,前对约为后对长的2倍。背鳞通身17行,除最外行其余微棱,腹鳞159～167．肛鳞二分,尾下鳞55～59对。背面暗橄榄褐色,体侧具多数淡黄色横斑,左右横斑彼此交错或在背中线相连;腹面色白或偶有灰点斑。雄性头腹前端鳞片（如颏鳞、颔片和前4～5对下唇鳞）上有多数疣粒,雌性则无。此蛇见于山溪或小河流水中,白昼隐藏于岩洞、石下、沙砾或杂草间,晚上或黄昏外出活动觅食,共采到5号标本,其叶14号均采于晚上20～22点之间,1号采于18点左右;被捕捉的蛇离水后两三天就死掉。此蛇也曾见于农耕地灌溉渠旁的杂草中。 山     

Phylogeography of the smooth snake Coronella austriaca (Serpentes: Colubridae): evidence for a reduced gene pool and a genetic discontinuity in Central Europe

The present study considers the genetic structure and phylogeography of the smooth snake (Coronella austriaca) in Central Europe, as analyzed on the basis of 14 microsatellite markers and a 284‐bp fragment of cytochrome b. We found deep divergence between western and south‐eastern Poland, suggesting at least two different colonization routes for Central Europe, originating in at least two different refugia. The west/south‐east divide was reflected in the haplotype distribution and topology of phylogenetic trees as defined by mitochondrial DNA, and in population structuring seen in the admixture analysis of microsatellite data. The well supported western European clade suggests that another refugium might have existed. We also note the isolation‐by‐distance and moderate‐to‐pronounced structuring in the examined geographical demes. Our data fit the assumption of the recently suggested sex‐biased dispersal, in that we found a strong divide in the maternal line, as well as evidence for a small but existent gene flow based on biparentally inherited microsatellite markers. All studied populations were very similar in respect of allelic richness, observed and expected heterozygosities, and inbreeding coefficients. However, some genetic characteristics were different from those expected compared to a similar fine‐scale study of C. austriaca from Great Britain. In the present study, we observed heterozygosity deficit, high inbreeding, and low Garza–Williamson indices, suggesting a reduction in population size. © 2015 The Linnean Society of London, Biological Journal of the Linnean Society, 2015, 115 , 195–210.     

Geographical variation in the genus Dendrelaphis (Serpentes: Colubridae) within the islands of south-eastern Indonesia

The south-eastern islands of Indonesia between Bali in the west and Timor in the east define a region that is at the interface of the Asian and Australasian biogeographic regions. Three subspecies of the colubrid snake Dendrelaphis pictus have previously been recognized from the region: Dendrelaphis pictus pictus (Bali and Lombok); D. p. inornatus (Sumba to Timor); and D. p. intermedius (Sumbawa to Alor). A re-examination of Dendrelaphis pictus in this region uses multivariate statistics to examine the geographic variation in head-shield and body measurements within the species. The findings re-interpret the taxonomy, indicating that D. pictus from Bali and Lombok are specifically different from D. inornatus on the remaining islands on the Banda Arc. The populations of D. inornatus on the islands of Sumbawa, Sumba, Sawu, Flores, and Lembata are subspecifically different from those on Roti, Semau, Timor, Alor, and Wetar.
Several head-shield measures are strongly correlated with longitude within D. inornatus , suggesting environmentally triggered selection gradients. However, for many variables, the two subspecies differ significantly in the direction of the trends which suggests the subspecies respond differently to these environmental gradients. There is evidence that Dendrelaphis individuals may be transported through the islands by anthropogenic agencies.     

Population genetic structure and geographic differentiation in the hot spring snake Thermophis baileyi (Serpentes, Colubridae): indications for glacial refuges in southern-central Tibet

The endangered hot spring snake (Thermophis baileyi) is endemic to the Tibetan Plateau and restricted to a few sites at high altitudes (>3500 m a.s.l.). Its strong preference for habitats with hot springs might be an early adaptation to the cooling climate during the plateau uplift. Some of these thermal sites may have been free of ice during the last glacial maximum (LGM) serving as refuges for the snake. To test this and to examine the population genetic structure data of 12 microsatellites and mitochondrial DNA were obtained from 153 individuals from 12 sites across the plateau. Four of the microsatellite loci were newly developed for this study. The results suggest that T. baileyi has at least two genetically diverse clades in Tibet, which developed during the Pleistocene and expanded after the LGM. Accordingly, the existence of separate glacial refuges on the central plateau can be assumed. Analyses of the genetic variation indicated a high level of geographic differentiation and population structure on a regional as well as on a range-wide scale. The study shows that, apart from the phylogeographic signatures, the diversification of current Thermophis populations is caused by (a) a limited dispersal due to mountain ranges, (b) a strong preference for hot springs and (c) the insular distribution of suitable habitats on the plateau. The present data should be taken into account in necessary monitoring and management plans for T. baileyi.     

翠青蛇产卵及孵化报道

翠青蛇(Cyclophiops major)隶属游蛇科(Colubridae)翠青蛇属.国内分布于秦岭以南各省,国外分布于越南、老挝(Deuve 1961,赵尔宓等 1998,赵尔宓 2006,杨大同等 2008).赵尔宓等(1998)记载解剖个体具8～10枚卵,橙黄色,卵径(14～17) mm× (37～38) mm...