Dendrophidion prolixum CADLE, 2012
Can you confirm these amateur observations of Dendrophidion prolixum?
|Higher Taxa||Colubridae, Colubrinae, Colubroidea, Caenophidia, Alethinophidia, Serpentes, Squamata (snakes)|
|Synonym||Dendrophidion prolixum CADLE 2012|
Drymobius dendrophis — BOULENGER 1913: 1034
Dendrophidion percarinatum — DUNN 1944: 477 (part)
Dendrophidion prolixum — WALLACH et al. 2014: 226
|Distribution||Colombia (Valle del Cauca, Chocó, Nariño), Ecuador|
Type locality: Quebrada Guanguí, 0.5 km above Río Patia (upper Saija drainage), 100–200 m elevation, Cauca department, Colombia [about 02°50’N, 77°25’W]
|Types||Holotype: AMNH 109721; Figs. 10–11 in Myers, 1991: 8]. Collected 9 February 1973 by Charles W. Myers and John W. Daly (field number C. W. Myers 11618).|
|Diagnosis||Diagnosis. Dendrophidion prolixum is characterized by (1) dorsocaudal reduction from 8 to 6 occurring anterior to subcaudal 27 (range, 8–26); (2) divided anal plate; (3) subcaudal counts >130 in males and females and adult tail length >60% of SVL; (4) subadults with narrow pale cross- bands or transverse rows of ocelli separated by >3 dorsal rows on the neck (adults retain bands or become predominantly brown or green without distinct pale bands); total number of pale bands on the body fewer than 60 (range, 49–57) when they are distinct; (5) ventrals immaculate or (in some adults) with narrow transverse dark lines across the anterior border of each ventral plate; (6) in life, head reddish brown and dorsum mainly green (brownish green in juveniles); and (7) everted hemipenis of ‘‘gracile’’ morphology, with an exceptionally long, slender hemipenial body proximal to an expanded tip bearing spines, calyces, and other apical ornamentation (retracted hemi- penis nearly always to subcaudal 10 or greater); total number of enlarged spines on the hemipenis >60 (65–89 in four organs studied).|
‘‘Gracile’’ hemipenial morphology will distinguish D. prolixum from all other species of Dendrophidion except D. graci- liverpa described herein and perhaps D. bivittatum (see above comments where the gracile morphology is described). Dendro- phidion bivittatum has a different color pattern (greenish dorsum with prominent blackish longitudinal stripes), a tail <60% of SVL, and fewer than 130 subcaudals.
Dendrophidion prolixum differs from species of the D. dendrophis species group (D. dendrophis, D. atlantica, D. nuchale auctorum, D. apharocybe, D. crybelum, D. vinitor) in having a reduction in the dorsocaudal scales anterior to subcaudal 30 (posterior to subcaudal 30 in the D. dendrophis group except occasional fe- males). A high number of subcaudals and divided anal plate will distinguish it from D. apharocybe, D. crybelum, and D. vinitor (<130 subcaudals and anal plate nearly always single in these species). Dendrophi- dion dendrophis and D. nuchale auctorum may have either single or divided anal plates, but these species have different color patterns, usually involving numerous narrow pale bands and/or ocelli (see Savage, 2002: 654–655, for discussion of D. nuchale), attain greater body sizes, and have different hemipenial morphologies (robust morphol- ogy and enormously enlarged spines in D. dendrophis and D. nuchale). Dendrophi- dion prolixum differs from D. boshelli in having 17 midbody scale rows (15 in D. boshelli).
Dendrophidion paucicarinatum lacks dis- tinct pale crossbands and has a higher number of ventrals than D. prolixum (>175 compared with <165 in D. pro- lixum). Dendrophidion paucicarinatum may have either a single or divided anal plate. Dendrophidion prolixum differs from D. brunneum in color pattern (adult D. brun- neum generally lack pale bands) and in hemipenial morphology (robust in D. brun- neum; see Fig. 3 and Cadle, 2010).
Dendrophidion prolixum is distinguished from D. graciliverpa by the wide spacing of the pale dorsal bands on the neck (bands generally separated by >3 dorsal scale rows in D. prolixum, <3 dorsal rows in D. graciliverpa). Consequently, D. prolixum has fewer pale bands on the body when these can be discerned: 49–57 in D. prolixum compared with 57–87 in D. graciliverpa. In life D. prolixum has a reddish brown head and greenish body, compared with a green head and brown to gray body in D. graciliverpa. These two species are exceedingly similar in most characteristics (Table 1), and I discovered no consistent differences in hemipenial morphology between them in the few everted hemipenes examined when intra- specific variation is considered. Preserved specimens without discernible pale cross- bands are problematic to identify, and several specimens from the borderlands of northern Ecuador and southern Colombia are of questionable referral to either D. prolixum or D. graciliverpa.
Dendrophidion prolixum has previously been confused with D. percarinatum, and these species cannot be distinguished by traditional scutellation features other than a few mean character differences (Table 1). These two species differ in (1) color pattern: reddish brown head with a greenish brown to green body, and venter either immaculate or with dark transverse lines (D. prolixum) vs. head and body primarily browns to grays, and venter immaculate (D. percarinatum); (2) number of pale crossbands on the body: 49–57 and separated by >=3 dorsal scale rows on the neck (prolixum) vs. 71–96 and separated by <3 dorsal scale rows on the neck (percarinatum) (pale crossbands can be indistinct in either species, but especially adult D. prolixum); (3) relationship between the posterior supralabials and temporals (see Materials and Methods and Table 1): G pattern most commonly (D. prolixum) vs. P pattern most commonly (D. percarina- tum); (4) hemipenial morphology: gracile (prolixum) vs. robust (percarinatum); re- tracted hemipenes of D. percarinatum rarely extend to subcaudal 10, whereas retracted organs of D. prolixum nearly always extend beyond subcaudal 10. The strong differences between D. prolixum and D. percarinatum in color pattern and hemipenial morphology are maintained in the area of western Colombia where their geographic ranges overlap, including several localities of sympatry discussed later [from CADLE 2012].
|Comment||Distribution: see map in CADLE 2012 (Figure 18).|
Sympatry: Sympatry between Dendrophidion pro- lixum and D. percarinatum is documented at three localities in western Colombia: two in the Río San Juan drainage (Playa de Oro and Quebrada Pangala) and another at the Río Raposo just south of Buenaventura (Fig. 9 in Cadle 2012). At these localities the two species maintain their distinguishing characteristics as given in the above diagnoses and in Table 4. Documentation for these localities is provided by the following specimens: Playa de Oro (AMNH R-108468, percarinatum; AMNH R-108469, prolixum), Quebrada Pangala (AMNH R-123745 and R-123748, percarinatum; AMNH R- 123746–47, prolixum), and the Rı ́o Raposo just south of Buenaventura (USNM 151658, percarinatum; USNM 151659, prolixum). Two examples are presented in Figure 19. At Playa de Oro the documenting specimens are both males with everted hemipenes (Fig. 19A), which are described and illustrated later (see Figs. 39, 42) [from CADLE 2012].
Habitat: partly arboreal (Harrington et al. 2018).
|Etymology||The species name is the neuter form of the Latin adjective prolixus meaning ‘‘stretched far out’’ or ‘‘long,’’ used especially in reference to parts of the body. The reference is to the unusually long hemipenis of this species compared with most other Dendrophidion.|