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Toxicocalamus spilorhynchus KRAUS, KAISER & O'SHEA, 2022

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Higher TaxaElapidae (Hydrophiinae), Colubroidea, Caenophidia, Alethinophidia, Serpentes, Squamata (snakes)
Common Names 
SynonymToxicocalamus spilorhynchus KRAUS, KAISER & O'SHEA 2022: 1021
Toxicocalamus loriae X T. stanleyanus (part) – MCDOWELL 1969: 485
Toxicocalamus loriae Clade 2 – STRICKLAND et al. 2016: 671 
DistributionPapua New Guinea

Type locality: Saiko, 11 km SW Garaina, 7.9538°S, 147.0567°E, elevation 1856 m, Morobe Province, Papua New Guinea.  
TypesHolotype. BPBM 41381, an adult female collected by Allen Allison on 15 February 2012.
Paratypes (n = 12). Papua New Guinea: Morobe Prov- ince: same locality as holotype, BPBM 41390; Amu Creek, near Garaina, 7.9555°S, 147.0569°E, elev. 1660 m, BPBM 41391; Garaina, 7.89°S, 147.14°E, elev. 770 m, AMNH R-95624, R-101101, R-101103, R-103681, R-107203–04, MCZ R-152428–29, R-152431; Saurere, 7 km W Garaina, 7.9222°S, 147.0878°E, elev. 1440 m, PNGM 22767. 
DiagnosisDiagnosis: “A moderately sized member of the T. loriae Group (SVL up to 600 mm) with the following unique combination of characters: two scales covering vent; three infralabials contacting first genial; a single intergenial between posterior genials, widest posteriorly; preocular contacting nasal (87%) or not (13%), not contacting internasal (93.3%); relatively long snout (SNL/SNW mean = 1.16, range = 0.99–1.40); relatively large eye (EY/SNL mean = 0.22, range = 0.17–0.24); two postoculars (93%); usually three (67%) posterior temporals; ventral scale count sexually dimorphic with overlap (t12 = 3.7381, p = 0.001416), 172–184 ventrals in eight males, 178–197 in six females; subcaudals sexually dimorphic without overlap, 43–57 in males, 20–29 in females; SCR strongly sexually dimorphic, with the relative contribution of subcaudal scale number in males twice what it is in females (20.0–24.0 in males, 10.0–13.1 in females); pale parietal blotch usually absent (present in four small specimens); pale markings on prefrontals present; and venter uniformly yellow.” (Kraus et al. 2022)

Comparisons. “Toxicocalamus spilorhynchus can be distinguished from all other members of the T. loriae Group except T. loennbergii and T. vertebralis by its dark vertebral stripe. It is further distinguished from T. mattisoni, T. nigrescens, and adult T. nymani by its yellow venter (vs. grey, yellow barred with grey, or dark brown in those other species); from T. loriae in having only a single intergenial (vs. two in T. loriae); and from T. lamingtoni in overlapping but significantly different ventral and subcaudal counts in males (ventrals: 172–184 vs. 160–178 in T. lamingtoni, t15 = –3.0499, p = 0.004053; subcaudals: 43–57 vs. 41– 53 in T. lamingtoni, t15 = –1.8533, p = 0.041808), by having two scales covering the vent (vs. one scale in T. lamingtoni), and a white (vs. dark-brown in T. lamingtoni) tail spine. It can be distinguished from juvenile T. nymani by details of head patterning: in T. spilorhynchus the pale blotches on the prefrontals are typically fused into a continuous chevron or blotch across the snout (vs. one discrete small spot on each prefrontal in T. nymani), the pale nuchal collar is continuous and includes the posterior portion of the parietals (vs. the band is replaced by a single elongate spot on each side of the nape in T. nymani), and there is often a pale blotch on the anterior temporal and anterolateral portion of the parietal (vs. absent in T. nymani). The yellow venter and dark vertebral stripe make T. vertebralis most similar to T. loennbergii and T. vertebralis. It can be distinguished from T. loennbergii by having two postoculars (vs. one in T. loennbergii), three (vs. four) infralabials contacting the anterior pair of genials, a longer snout (SNL/SNW mean = 1.16, range = 0.99–1.40 vs. 0.95 and 0.93–0.99 in T. loennbergii), larger eye (EY/SNL mean = 0.22, range = 0.17–0.24 vs. 0.16 and 0.15–0.18 in T. loennbergii), and lacking a pale blotch on the parietals (present in T. loennbergii) except in four small specimens. Toxicocalamus spilorhynchus can be distinguished from T. vertebralis by both sexes having significantly fewer ventrals (172–184 in males vs. 194– 210 in T. vertebralis, t15 = –10.1025, p < 0.00001; 178– 197 in females vs. 203–232 in T. vertebralis, t14 = 6.0435; p < 0.000015) and more subcaudals (43–57 in males vs. 39–52 in T. vertebralis, t15 = 2.4970, p = 0.012326; 20– 29 in females vs. 31–38 in T. vertebralis, t14 = –5.8962, p=0.000019); a pale blotch on each prefrontal (vs. absent in [or vague in one] T. vertebralis); and having the yellow venter become dusted with brown on the anterior of each ventral scale in large adults (vs. uniformly yellow throughout life in T. vertebralis).” (Kraus et al. 2022)

Description of the holotype. “Adult female with mid- ventral slit extending through seven ventrals at midbody; 600 mm SVL+65 mm, TL=665 mmTTL. Rostral broader than high, notched ventromedially, not extending dorsoposteriorly as far as nares; internasals angulate, semi-triangular, wider than long; prefrontals distinct from preoculars, approximately square, wider anteriorly than posteriorly, angled posterolaterally (Fig. 12A, A’), bordered below by preocular and nasal; preoculars elongate, narrower anteriorly, approximately twice as long as deep, bordered anteriorly by nasal, below by second and third supralabials (Fig. 12B, B’, C, C’); frontal shield-shaped, lateral margins roundly angled obliquely, not fused with supraoculars, anterior margin extending slightly anterior to remainder of scale medially; parietals approximately twice as long as wide on right, shorter and wider on left. Nasals divided by large nares, with grooves above and below naris. Postoculars two, lower larger on right, subequal on left, both smaller than eye; one elongate anterior temporal above fifth and sixth supralabials, separating latter from parietal; two posterior temporals, lower abutting posterodorsal margin of sixth supralabial. Supralabials six, third and fourth contacting eye; infralabials six, first three in contact with anterior genial, third and fourth in contact with posterior genials. Mental small, shallow, triangular, wider than deep, bordered behind by first supralabials; anterior genials subequal to posterior genials, in medial contact along entire length; posterior genials separated along entire length; intergenial single, widest posteriorly; four gulars separate intergenial from first ventral in the midline; first sublabial separates posterior genial from fifth infralabial (Fig. 12D, D’). Eye relatively small; pupil round.
Dorsal scale rows 14-15-15, smooth, not notched posteriorly, without apical pits; on approximately posterior third of body vertebral scale row and sixth row on right composed of scales larger than adjacent rows. Ventrals 193, each approximately four times wider than long; two scales covering vent; subcaudals 29, paired. Tail tipped by a pointed conical spine.
In preservative (nine years after collection), dorsum pale brown, with poorly defined darker-brown vertebral stripe (Fig. 13A); each dorsal scale margined posteriorly in darker brown, giving the appearance of a reticulated dorsum. Venter and subcaudals dark yellow dusted with pale brown on anterior of each scale, imparting a clouded yellow appearance to venter (Fig. 13B). Supralabials pale yellow ventrally, suffused with brown dorsally as well as anteriorly on first supralabial. Yellow nuchal collar absent. Supraoculars, frontal, and posterior margin of prefrontals dark brown; scales anterior to this on snout light brown clouded with dark brown; posterior of parietals and scales behind them dark brown; anterior temporals and anterior portion of parietals lighter brown clouded with dark brown. Chin and throat dark yellow, dusted with small brown flecks on mental, first four infralabials, and anterior genials. Conical tail spine white, finely dusted with brown mid-dorsally. Iris black.” (Kraus et al. 2022)

Variation. “Ventrals 172–184 (178 ± 4) in eight males and 178–197 (190 ± 7) in six females; subcaudals 43–57 (51 ± 4) in eight males and 20–29 (26 ± 3) in six females. Tails in females are much shorter than in males, both in terms of adult tail length and relative subcaudal number.
TLR is 17.9–19.2% (18.4 ± 0.5%) in four adult males and 8.9–10.2% (9.6 ± 0.6%) in two adult females, whereas SCR is 20.0–24.0% (22.1 ± 1.2%) in eight males and 10.0–13.1% (11.9 ± 1.1%) in six females. Numbers of postoculars are two, except on the right side of BPBM 41391, which has one. Numbers of posterior temporals are usually three (67%) but sometimes two (29%) or four (4%). Preoculars typically broadly contact the nasals, except for two specimens (BPBM 41390–91) that have the two scales separated by broad contact between the prefrontal and second supralabial. Preoculars do not contact the internasals, being separated by the intervening prefrontal, except on the right side of MCZ R-152431, in which there is point contact between the two. Typically, only a single intergenial separates the posterior genials; however, smaller intercalary scales occur in five specimens, usually anterior to the intergenial, though lateral to it in one specimen. Posterior genials are entirely separated by the intergenial(s) in ten specimens, in minimal anterior contact in two, and in broad contact along 1⁄3 their length in one.
Specimens are brown dorsally with a dark-brown vertebral stripe and with each scale narrowly margined in dark brown posteriorly. The first rows of scales in small specimens are yellow, so that the dark-brown margining of each scale imparts the appearance of narrow brown stripes on the lower sides. Venters are uniformly yellow in smaller specimens (153–336 mm SVL) but each scale is clouded with pale brown anteriorly in the only large specimen (the holotype, 600 mm SVL). Juveniles are boldly patterned with yellow blotches on a black ground that typically involves a yellow chevron across the prefrontals, a yellow nuchal collar, and yellow blotches on the parietals and anterior temporals (Fig. 4K, L).
These become obscured in larger specimens, and the sole adult has very vague remnants of these markings on a brown ground and no nuchal collar. All specimens have yellow on the supralabials, ventral portion of the rostral, and usually on the posterior portion of the nasal. Chin and throat are typically uniformly yellow but may be dusted with brown along the margins of the anterior scales and are more heavily flecked with brown anteriorly in BPBM 41390–91.” (Kraus et al. 2022)

Colour in life. “A photo of MCZ R-152431, a small (225 mm SVL) male, shows a medium-brown animal with a narrow, black vertebral stripe that is typically strongest on the anterior of each scale and often disappears on the posterior portion, imparting a somewhat spotted appearance to the stripe (Fig. 11C). The lower sides are narrowly striped with black anteriorly, becoming more continuously dark posteriorly, and most dorsal scales appear narrowly margined in black posteriorly, imparting a reticulate appearance to the dorsum. Top of the head is black, with yellow mottling on the snout, parietals, anterior temporal, and nuchal region. The region immediately behind the nuchal region is black, but this abruptly changes to the brown dorsal colouration of the body. Supralabials, anterior preocular, and posterior nuchal yellow (Fig. 11D).” (Kraus et al. 2022) 
EtymologyNamed after the Greek σπίλος (spilos = spot) and ῥῠ́γχος (rhynchos = snout), in recognition of the distinctive prefrontal blotch that typifies the species. 
  • Kraus, F., Kaiser, H., & O’Shea, M. 2022. Hidden diversity in semi-fossorial Melanesian forest snakes: A revision of the Toxicocalamus loriae complex (Squamata, Elapidae) from New Guinea. Vertebrate Zoology, 72, 997-1034 - get paper here
  • McDowell, Samuel B. 1969. Toxicocalamus, a New Guinea genus of snakes of the family Elapidae. Journal of Zoology, London 159: 443-511 - get paper here
  • Strickland, J. L., Carter, S., Kraus, F. and Parkinson, C. L. 2016. Snake evolution in Melanesia: origin of the Hydrophiinae (Serpentes, Elapidae), and the evolutionary history of the enigmatic New Guinean elapid Toxicocalamus. Zoological Journal of the Linnean Society.doi: 10.1111/zoj.12423 - get paper here
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