Chapinophis xanthocheilus CAMPBELL & SMITH, 1998
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Chapinophis xanthocheilus
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| Higher Taxa | Colubridae (Dipsadinae), Colubroidea, Caenophidia, Alethinophidia, Serpentes, Squamata (snakes) |
| Subspecies | |
| Common Names | |
| Synonym | Chapinophis xanthocheilus CAMPBELL & SMITH 1998 Chapinophis xanthocheilus — KÖHLER 2008 Chapinophis xanthocheilus — WALLACH et al. 2014: 157 |
| Distribution | C Guatemala (Sierra de las Minas, 1830-2300 m elevation) Type locality: 5 km ENE Finca Miranda on trail to Aldea Vega Larga, 2300 m elevation, Baja Verapaz, Guatemala. |
| Reproduction | oviparous |
| Types | Holotype: UTA 35919, a 518 mm male (8 April 1993; R.F. Savage). |
| Diagnosis | Diagnosis: A Central American xenodontine snake of uncertain affinities. This snake may belong in the group referred to as "goo eaters" (Cadle and Greene, 1993; Femandes, 1995a) containing eight genera (Adelphicos, Atractus, Chersodromus, Geophis, Ninia, Dipsas, Sibon, and Sibynomorphus) exclusive of Chapinophis. Within this group, Chapinophis may be most closely related to the fossorial genera Adelphicos, Geophis, and Atractus, which together with Ninia and Chersodromus form the Adelphicos clade (Femandes, 1995a). Chapinophis differs from all other genera of Central American xenodontines, as well as other snakes in the Neotropical region, by having 17 longitudinal dorsal scale rows at midbody that are reduced anteriorly, but not posteriorly, to 15 rows and the following combination of characters. The genus Chapinophis is more elongate and has more ventrals (178-196) than Adelphicos (120-147), Chersodromus (124-142), or Ninia (122-157). Single species within the speciose genera Atractus and Geophis are known to have up to 189 and 185 ventrals, respectively (Downs, 1967; Peters and Orejas-Miranda, 1970), but the range of ventrals for most species is well below the minimum number known for Chapinophis, and species in these genera have relatively stouter bodies. Among the "goo eaters", only Adelphicos shares a divided anal scute with Chapinophis; Atractus, Geophis, Chersodromus, and Ninia have undivided anal scutes. The dorsal scales of Chapinophis are smooth and lack apical pits, the tail is relatively short, and there are 29-40 paired subcaudals. The eye is relatively small, being contained 1.9-2.2 times in the length of the snout (distance from anterior edge of orbit to front face of rostral),and the pupil is round. The general elements of color pattern are unusual, but not unique, among Middle American snakes, consisting of a broken pale dorsolateral line and yellow markings on the upper jaw. In Chapinophis,the hemipenis is bicapitate (versus unicapitate in Adelphicos, Ninia, Dipsas, Sibon, and Sibynomorphus), bilobate (versus single in Sibon and Sibynonorphus), and with numerous spines covering most of the lobes except the capitula which occupy about the distal fourth of each lobe and are covered with calyces. The hemipenis in most members of the genus Dipsas is single, but at least in Dipsas neivai the organis bilobed (Portoand Fernandes, 1996). In contrast with Chapinophis, most species of Geophis have a distinctly unicapitate hemipenis;however,the organ may also be semicapitate (latifrontalis and dubius groups) or non-capitate (championi group) according to Downs (1967). Likewise,hemipenial morphology is variable within the genus Atractus with a few southern South American species having a capitate condition with distal calyces and others lacking hemipenial capitation; the former condition was considered primitive by Fernandes (1996). Certain features of the Adelphicos clade of "goo eater" genera are compared in Table 1. Among Neotropical snakes, the Pseudoboini are known to have bicapitate, bilobed hemipenes (Jenner and Dowling, 1985; Myers and Campbell, 1981). Chapinophis differs profoundlyin two respects from pseudoboine snakes and probablyis not closely related to this group of snakes. First, the maxilla of Chapinophis is syncranterian and thus differs from that found in all pseudoboines which are diacranterian. Secondly, the sulcus spermaticus in Chapinophis is centripedal rather than centrifugal.The latter condition characterized pseudoboine snakes. In some respects, Chapinophisis reminiscent of certain species of Rhadinaea andthe monotypic genera Rhadinophanes, Tantalophis, and Crisantophis. Among Neotropical snakes, other than Chapinophis, only Rhadinophanes and Tantalophis are known to have long and slender, bicapitate, bilobed hemipenes with calyces and centripedalsulci spermatici.The hemipenes are similar in Crisantophis, but are non-capitate and lack calyces. Chapinophis differs dramatically from Rhadinophanes, Tantalophis, and Crisantophis in dentition. The posterior maxillary teeth are enlarged in the latter three genera and a diastema separating the enlarged rear maxillary teeth is usually present in Rhadinaea and Crisantophis; a small diastema may also be variably present or absent in Rhadinophanes. In Chapinophis, the last several posterior maxillary teeth are conspicuously smaller than the preceding teeth and there is no diastema. Chapinophis further differs from all of these genera in having a single scale between the postnasal and orbit with the prefrontal scale contacting the orbit. Both a preocularand loreal scale are present in Rhadinophanes, Tantalophis, and Crisantophis, and the prefrontal does not contact the orbit. Certain features of Chapinophis are compared with other Central American genera of snake shaving similar hemipenes in Table 2 (Campbell & Smith 1998). |
| Comment | Abundance: only known from the specimen(s) described in the original description (fide Campbell et al. 2018) Shares certain features, especially the maxilla, with Adelphicos, Geophis, Atractus and may be in the clade containing these snakes, Ninia, and Chersodromus. The hemipenial morphology appears to be similar to Rhadinophanes and Tantalophis. Type species: Chapinophis xanthocheilus CAMPBELL & SMITH 1998 is the type species of the genus Chapinophis CAMPBELL & SMITH 1998. |
| Etymology | The generic name is derived from the Guatemalan colloquialism Chapín, referring to a Guatemalan or something from Guatemala, and the Greek ophis, meaning a serpent. The generic name is masculine. |
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