Drymoluber dichrous (PETERS, 1863)
Can you confirm these amateur observations of Drymoluber dichrous?
|Higher Taxa||Colubridae, Colubrinae, Colubroidea, Caenophidia, Alethinophidia, Serpentes, Squamata (snakes)|
|Common Names||Northern Woodland Racer|
|Synonym||Herpetodryas dichroa PETERS 1863: 284|
Spilotes piceus COPE 1868: 105 (fide BOULENGER 1894)
Herpetodryas occipitalis GÜNTHER 1868: 420
Spilotes piceus COPE 1868: 105
Coluber dichrous — BOULENGER 1894: 30
Elaphe dichrous — GOMES 1918
Drymoluber dichrous — AMARAL 1930: 337
Drymoluber dichrous — DUELLMAN 1978: 241
Drymoluber dichrous — GASC & RODRIGUES 1980
Drymoluber dichrous — BAUER et al. 1995: 72
Drymoluber dichrous — KORNACKER 1999: 84
Drymoluber dichrous — WHITHWORTH & BEIRNE 2011
Drymoluber dichrous — WALLACH et al. 2014: 247
|Distribution||Colombia, Ecuador, E Peru, N Brazil (Alagoas [HR 31: 55], Minas Gerais [HR 33: 324], Pará, Espírito Santo, Bahia, S Ceará, Rio de Janeiro, Paraíba), Venezuela (TF Amazonas), Bolivia, French Guiana, Suriname, Guyana; elevation 0-3500 m|
Type locality: “Brasilien [und] angeblich aus Surinam”
|Types||Syntypes: ZMB 1661-2; Lectotype: ZMB 1661 (unclear sex, but probably male), designated by COSTA et al. 2013|
Holotype: ANSP 3920; Peru, Napo or upper Marañon; originally at USNM [piceus]
|Diagnosis||Diagnosis (genus): Drymoluber is distinguished from all other Neotropical Colubrinae by the following combination of characters: a) dorsal scales smooth, in 13, 15 or 17 midbody rows; b) cloacal shield entire (rarely divided); c) 157– 202 ventrals; d) 84–127 divided subcaudals; e) caudal pseudoautotomy; f) two pairs of chinshields, the first about half the length of the second; g) 8 (less commonly 7 or 9) supralabials; h) 8 or 9 (less commonly 7 and 10) infralabials; i) 1 (rarely 2) preocular; j) 2 (rarely 1 or 3) postoculars; k) 14–26 maxillary teeth; l) ontogenetic variation in the dorsal coloration of body and head (small specimens have dark and white/red colored macules on the head, and the body with dark crossbands separated by light interspaces, while large specimens have dorsal coloration uniformly green, brown or gray); m) hemipenes single, subcylindrical, not capitate, with the lobe about half the length of the organ, ornamented with papillate calyces gradually replaced by spinulate flounces and spines. The spines are arranged in more or less transverse rows, those bordering the sulcus spermaticus having a basal hook [COSTA et al. 2013]|
Diagnosis (species): Drymoluber dichrous is distinguished from D. brazili and D. apurimacensis by the following combination of characters: a) 15-15-15 dorsal scale rows with two apical pits; b) 157–173 ventrals in males, 160– 180 in females; c) 87–110 subcaudals in males, 86–109 in females; d) 19–26 maxillary teeth. See Table 5 in COSTA et al. 2013.
Comparisons: Drymoluber brazili has 17-17-15 dorsal scales rows, and D. apurimacensis has 13-13-13. Apical pits are absent in D. apurimacensis. Drymoluber brazili has 182–200 ventrals in males and 185–202 in females, 109–127 subcaudals in males and 109–126 in females. Drymoluber apurimacensis is not distinguishable from D. dichrous based on ventrals and subcaudals counts, having 158–164 ventrals in males and 166–182 in females, 84–93 subcaudals in males and 87–91 in females. Drymoluber apurimacensis has 14–16 maxillary teeth.
Small specimens of D. dichrous have dark crossbands 1.5–7 scales wide (mean 3.6) and light interspaces 0.5– 2.5 scales wide (mean 0.8), while in D. apurimacensis the dark crossbands are 1–2 scales wide, and the pale interspaces are 2–3 scales wide. Juvenile specimens of D. brazili have dark crossbands of similar width to those of D. dichrous (2–6 scales; mean 3.6), but the pale interspaces are wider (0.5–5 scales; mean 1.6).
The hemipenes of D. dichrous tend to have more calyces than D. brazili, smaller spinulated flounces, and no spines in the lobular region. The walls of the sulcus spermaticus tend to have more ornamentation, at least in the lobular region, with small jagged papillae. The spines of the asulcate face are generally larger than those of D. brazili, especially those most proximal. The hemipenial morphology of D. dichrous and D. apurimacensis is similar and of little value in differentiating these species [COSTA et al. 2013]
|Comment||Type species: Herpetodryas dichroa PETERS 1863: 284 is the type species of the genus Drymoluber PETERS 1863.|
|Etymology||Etymology (genus): Amaral (1930) stated that the dentary and hemipenial characters of Herpetodryas dichroa Peters, 1863 suggested that was a taxon closely related and intermediate between Drymobius and Coluber. The generic name Drymoluber (an amalgam of the words Drymobius and Coluber), was proposed to simultaneously distinguish and show the close relationship between Herpetodryas dichroa (now Drymoluber dichrous) and those genera. The name Drymoluber is masculine in gender [COSTA et al. 2013].|
Peters (1863) did not comment on the reasons that led him to choose the name dichroa for the species he described. The words dichroa / dichrous comes from the ancient Greek, meaning “two-colored” or “two-skins”, and we suggest that the name may be an allusion to the contrasting color of adult specimens, which dorsum is dark colored, while the venter is light colored [COSTA et al. 2013]
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