Acrochordus arafurae MCDOWELL, 1979
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|Higher Taxa||Acrochordidae, Caenophidia, Alethinophidia, Serpentes, Squamata (snakes)|
|Common Names||E: Arafura filesnake|
|Synonym||Acrochordus arafurae MCDOWELL 1979|
Acrochordus arafurae — MCDIARMID, CAMPBELL & TOURÉ 1999: 226
Acrochordus arafurae — COGGER 2000: 615
Acrochordus arafurae — WILSON & SWAN 2010
Acrochordus arafurae — WALLACH et al. 2014: 7
|Distribution||E Indonesia, New Guinea, N Australia (coastal areas of Northern Territory, Queensland)|
Type locality: Lake Daviumbo, western Province.
|Reproduction||ovovivparous. Acrochordus arafurae may be the second parthenogenetic snake species (after Ramphotyplops braminus).|
|Types||Holotype: AMNH 59887|
|Diagnosis||Diagnosis (see also key to species of Acrochordus above). Differing from other species of Acrochordus in each of the following features: 1) nasal bones fused anteriorly; 2) hemipenis forked only at extreme tip, without spines or papillae; 3) pattern with intricate network of dark markings that are connected with one another but isolate spots of the brown or tawny ground colour. Additionally differing from A. javanicus (but resembling A. granulatus) in 1) absence of coronoid process on lower jaw; 2) posterior dentary teeth resembling other teeth in form; 3) scales of sides with one main cusp, flanked by much smaller cusps; 4) nasal bones tapering to a median anterior point; 5) maxillary teeth fewer (16-19); 6) dentary teeth fewer (13-17). Additionally differing from A. granulatus (but resembling A. javanicus) in: 1) nostrils directed forward, without upward inclination, separated from eye by 11-14 scales (against 5-7); 2) scales of lips less enlarged, with more rows (8-11, against 5-7) between eye and edge of lip; 3) long pterygoid row of 11-16 (against 5-7) teeth; 4) no transversely enlarged scale behind nasal; 5) less compressed tail, its vertical diametre much less than twice its horizontal diametre. (The hemipenial characters of this diagnosis checked on all males of material listed above; external, osteological, and dental characters checked on all material listed above, except nasal bones not checked for MCZ 118668, 118669, 118765, and 129121. In addition, vertebrae in region of heart checked on AMNH 86182 [Borroloola, Northern Territory] and found to have short neural spine confined to posterior edge of neural arch, essentially as in A. granulatus but unlike the high neural spine that arises from most of the length of the neural arch in A. javanicus and the Miocene-Pliocene A. dehmi Hoffstetter  ).|
Description. Nostrils directed forward, near tip of snout, each nostril surrounded by circular nasal scute that forms a narrow rim; nasal scutes separated from each other by a granular scale at their closest approximation; nasal-eye scales 11-14 (13 bilaterally in holotype; for total of left and right, range 22-28, mean 24.5, s = 1.91, sy = 0.39, N = 24); eye-eye scales = 17-21 (holotype with 18; mode 19; mean = 18.7, § = 1.12, sx̅ 0.23, N = 24); eye-lip scales 8-11 (11 left, 10 right in holotype; for sum of left and right, range 16-22, mean = 19.0 S = 1.49, sx̅ = 0.03, N = 24); no enlarged scales on dorsal aspect of head, the scales behind nasal small, granular; supralabials only slightly enlarged, 28-36 (35 bilaterally in holotype; for sum of left and right, range 54-70, mean = 61.25, s = 5.03, s = 1.45, N = 12); infralabials 23-30 (25 left, 24 right in holotype; for sum of left and right, range 47-57; mean = 51.3, = 3.50, sx̅ = 1.01, N = 12); corner of mouth concealed from lateral view by rictal fold, thus defining a scale-lined pocket at corner of mouth; rostral and mental scutes barely visible externally, but extending within mouth as distinct cornifications; middle of lower lip produced forward as a median lobe fitting closely into median notch of upper lip; no mental groove defined by modified scales or median depression. Scales of body juxtaposed, for most part not exposing any granular areas between them; on sides, each scale with prominent conical central cusp that extends backward past margin of base of scale, flanked by a more dorsal and a more ventral cusp, each much less developed than central cusp and often poorly defined; along back, central cusp less prominent, but along midline of belly the central cusp more developed, So that a median belly fold with 3 or 4 longitudinal scale rows is at least suggested; scales at midbody 120-178 (166 in holotype; mean = 147.7, S = 16.32, sx̅ =4.71, N = 12). No anal scute, the cloacal region U-shaped, the arms of the U directed backward as a pair of pockets into which anal glands open and which are continued backward within tail by hemipenes of males; lining of cloaca with granular scales near cloacal lips (AMNH 59886 and MCZ 118765, adult females, preserved with cloaca protruded as scaly tube that expands distally, the lateral pockets being completely everted; this perhaps an artifact of preservation, but probably possible during life, at least for females, thus explaining the extension of scaly skin within lining of cloaca and the deep lateral pockets of cloaca); tail nearly round in cross-section, about 13-20 percent of total length [since most of my specimens are either skinned out between neck and cloaca or else hardened in coils, only general order of magnitude can be determined].
Teeth: Maxillary teeth 16-19 (mode 18; mean = 17.6, S = 0.95; Sy 0.18, N = 29; counts by Stimson of 5 British Museum specimens included), shortest posteriorly, but because of downward curvature of rear of maxilla, tips of all teeth lying virtually on a straight line; palatine teeth 8-10 (mode 9; mean = 9.0, s = 0.42, Sy = 0.09, N = 24); pterygoid teeth 11-16 (mode 15; mean = 13.7, s = 1.33, S% = 0.27, N = 24); palatine-pterygoid teeth gradually diminish ing in length from before backward, last palatine tooth subequal to first pterygoid; last pterygoid tooth beneath pterygoid-ectopterygoid articulation; dentary teeth 13-17 (mode 17; mean = 15.75, 5 = 1.15, S = 0.24, N = 24), longest anteriorly (except for first 1 or 2), the most posterior similar in form to the other teeth. Compound bone of lower jaw without coronoid process, unless this process is represented by a triangular dorsolateral projection located near quadrate articulation; at least in holotype, dentary with two mental foramina (as in A. javanicus) but splenial of simple triangular form without anterodorsal notch (thus, as in A. granulatus); ectopterygoid smoothly arched, not dilated except at its articulations with maxilla and pterygoid; nasal bones fused anteriorly to form pointed median anterior process, suturally distinct posteriorly; at least in holotype, nasals and septomaxillae not in contact with frontal, and frontal-prefrontal contact confined to region dorsal to lachrymal foramen.
Hemipenis of holotype 56 mm long, forked for the terminal 3 mm; sulcus spermaticus forked at forking of organ, with prominent lips that have well defined absulcal edges; lips of forked portion of sulcus expanded into pair of smooth pallets; no spines or papillae, but longitudinal folds, one of which fuses proximally with medial lip of sulcus. In AMNH 86183 (Borroloola, Northern Territory), preserved with both hemipenes incompletely everted, organ similar to that of holotype, directed downward and distinctly craniad (as in Colubroidea; in Booidea the everted organ points caudad), narrow and loosely helical. For 5 adult males, hemipenial length 29.0-63.7 mm (mean = 50.5 mm), forked portion 1.5-3.6 mm (mean = 2.6 mm), not significantly correlated with total length (r = 0.589, not significant for 3 degrees of freedom); length of furcation, in percent of total length: 3.7-8.6 (Stimson, pers. comm. finds the organ forked for 5 percent of its length in a British Museum specimen from Mimika River, Irian Jaya). Pattern of juvenile (BBM 3092): Lips yellow, with dark spotting at tip of muzzle; top of head brownish black with pale tawny postocular oval and tawny mottling on crown, condensed to a tawny blotch on dorsal side of muzzle; body tawny fading to yellowish white on belly, with black reticulations that take up less area than ground colour anteriorly, but pre dominate on rear of body and tail; underside of tail black with yellow spots; roof of mouth be tween palatines and floor of mouth (except median region from larynx forward) dark brown; tongue grey, fading to white on tips. This pattern retained in adults (including holotype), but ground colour darkens with age to dark olive, reducing contrast with black reticulations and pattern becomes incon spicuous, even on head.
|Etymology||Named after the type locality in the Arafura Sea.|
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