Toxicocalamus mattisoni, Kraus, 2020

Kraus, Fred, 2020, A new species of Toxicocalamus (Squamata: Elapidae) from Papua New Guinea, Zootaxa 4859 (1), pp. 127-137 : 128-131

Toxicocalamus mattisoni , sp. nov.

Figures 1 , 2

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Holotype. BPBM 17988 (field tag FK 7524 ), obtained from local villagers, Siyomu Village , 10.0145° S, 149.5970° E, 1300 m a.s.l., N slope of Mt. Simpson, Milne Bay Province, Papua New Guinea, on 23 February 2003.

Paratypes (n = 6). Papua New Guinea: Milne Bay Province: N. slope of Mt. Simpson: Siyomu ( BPBM 17987 , 18165 , PNGNM R-25152 ); Bunisi Village , 10.0171° S, 149.6002° E, 1420 m a.s.l. ( BPBM 17989 , 18166 ) ; Camp 2, 0.5 km SW Bunisi, 10.0209° S, 149.5947° E, 1490 m a.s.l. ( BPBM 18164 ) .

Diagnosis. A moderately sized species of Toxicocalamus (maximum SVL = 483 mm) having 15-15-15 scale rows, 170–181 ventrals, 33–49 paired subcaudals, divided anal plate, preocular distinct from prefrontal, separated from nasal by prefrontal contact with second supralabial; frontal unfused with supraoculars; internasals unfused; one postocular; one anterior temporal, 2–3 posterior temporals; six supralabials, second in contact with prefrontal, excluding contact between preocular and nasal; uniformly gray or brown dorsum; and venter pale gray or yellow with gray bands across each ventral scale.

The new species differs from T. holopelturus McDowell in having divided (vs. entire) subcaudals; from T. buergersi (Sternfeld) , T. cratermontanus Kraus , T. longissimus Boulenger , T. mintoni Kraus , T. misimae McDowell , T. preussi (Sternfeld) , and T. stanleyanus Boulenger in having the preocular distinct from (vs. fused to) the prefron- tal; from T. pumehanae O’Shea, Allison & Kaiser in having the prefrontal distinct from (vs. fused to) the internasal; from T. pachysomus Kraus by its slender habitus (vs. robust in T. pachysomus ) and in having the internasal and preocular not in contact (vs. internasal and preocular in contact in T. pachysomus ); and from T. ernstmayri , T. grandis , and T. spilolepidotus McDowell in its unspotted, uniformly gray or brown dorsal color (vs. yellow brown spotted with dark brown in T. ernstmayri , dark brown with whitish blotches in T. grandis , black with each scale containing a pale-yellow spot in T. spilolepidotus ).

Toxicocalamus mattisoni is most similar in scalation to T. loriae , T. nigrescens , and nomina currently synonymized with T. loriae ( Apistocalamus pratti , A. loennbergii , A. lamingtoni , and Pseudapistocalamus nymani ). It differs from A. lamingtoni in having a divided (vs. single) anal plate and from all the remainder except A. loennbergii in having the preocular not contacting the nasal due to contact between the prefrontal and second supralabial (vs. preocular contacting nasal in T. loriae and T. nigrescens ). In A. loennbergii , the preocular and nasal scales may or may not be in contact, being narrowly separated in BMNH 1946.1.18.24 on the right side and in point contact on the left; they are in contact in BMNH 1946.1.18.25–26. Toxicocalamus mattisoni differs from A. loennbergii in having fewer ventrals (170–181 vs. 213–220 in A. loennbergii ) and a gray or yellow venter with each ventral barred in darker gray (vs. uniform bright yellow in A. loennbergii ). Toxicocalamus mattisoni further differs from T. loriae (and A. pratti ) in having a gray or yellow venter with each ventral barred in darker gray (vs. yellow, usually with a mid-ventral row of brown spots in T. loriae ) and from T. nigrescens in its smaller size (SVL up to 483 in T. mattisoni vs. up to 635 in T. nigrescens ) and paler dorsal color (medium gray or brown in T. mattisoni vs. dark charcoal gray or gray brown in T. nigrescens ).

Description of Holotype. Adult female. Rostral broader (2.8 mm) than high (2.1), notched ventromedially; internasals angulate, semi-triangular, wider (right 2.1, left 2.0) than long (right 1.4, left 1.3); prefrontals distinct from preoculars ( Fig. 1A ), longer than wide (2.7 x 2.4 on right), bordered below by preocular, second supralabial, and nasal; preoculars elongate, narrower anteriorly, twice as long as deep, bordered anteriorly by second supralabial; frontal shield-shaped, not fused with supraoculars ( Fig. 1B ); parietals more than twice as long as wide (length 6.7, width 2.9 on right). Nasals divided by large nares, each with shallow groove below naris, but shallow groove above naris only on left side, naris reaching top of right nasal scale; postocular single, crescentic, approximately same size as eye; one elongate anterior temporal lies above fifth and sixth supralabials, separating the latter from parietal; two posterior temporals, upper larger, lower abutting posterodorsal margin of sixth supralabial. Supralabials six, third and fourth contacting eye; infralabials six, first three in contact with anterior genial. Mental small, shallow, triangular, wider (2.2) than deep (0.9); anterior genial longer (2.9) than posterior (2.6); posterior genials separated along posterior length by single diamond-shaped intergenial; first two gulars separate posterior genials from fifth infralabials. Eye relatively small (1.25); pupil round.

Dorsal scale rows 15-15-15, smooth, un-notched posteriorly, without apical pits. Ventrals 177, each approximately four times wider than long; anal divided; subcaudals 33. Dorsal scales on tail reduced to nine rows at level of subcaudal 3, to six rows at level of subcaudal 11, and to five rows at level of subcaudal 25. Tail tipped by a blunt conical spine.

In preservative, dorsum uniformly medium brown, each scale tipped posteriorly with dark brown; each ventral scale pale straw-yellow stippled with a narrow band of brown along anterior margin, giving the venter a pale yellowand-brown appearance. Brown ventral banding gradually increasing posteriorly; each subcaudal darker brown with narrow pale straw-yellow posteriorly. Supralabials pale yellow suffused with brown on fifth and sixth supralabials and lower posterior temporal. Chin pale straw yellow with brown suffusion on mental, infralabials, and anterior genials. Iris black.

Measurements of the Holotype (in mm). —Total length = 546, snout-vent length = 483, tail length = 63, eye-naris distance = 3.4, internarial distance = 3.0, eye width = 1.25, head length = 12.5, mass = 51.5 g.

Variation. Adult specimens vary in SVL from 420–483 mm; the sole juvenile has an SVL of 207 mm ( Table 1 ). The juvenile had a mass of 4.9 g; the adults varied from 21.4–51.5 g. Scalational variation is minor ( Table 1 ). BPBM 18165 has the anterior half of the anterior temporal on each side fused to the sixth supralabial. Two specimens have a tiny third posterior temporal inserted at the posterior end of the anterior temporal ( Table 1 ). In preservative, color variation is minimal. The juvenile is medium gray above, whereas the adults are brown. The dark ventral banding varies from light to heavy but typically covers two-thirds of each ventral. There is a trace of a nuchal collar in most specimens, but it is typically confined to the sides of the neck and is slightly paler brown than the surrounding dorsum; only in the juvenile does the collar have much yellow on the sides. The supralabials are straw yellow suffused with brown in the adults but lack the brown suffusion in the juvenile.

Color in Life. From notes in life, I described the holotype as “Dorsum olive brown. Head black. Lips lemon yellow, remainder of belly light yellow, with gray suffusion anteriorly. Under tail charcoal gray.” Small amounts of yellow can be seen on the prefrontals of the holotype in a photo of that animal ( Fig. 2 ). Adult paratype BPBM 17989 had a gray dorsum changing to olive brown on lower sides; venter dusky yellow-orange with each ventral having a gray anterior margin; black under the tail; lips and nuchal collar dusky yellow-orange. The juvenile paratype (BPBM 17987) was: “Dorsum gray, darker on head. Lips lemon yellow, chin yellow with gray cast, remainder of venter gray with purplish cast.”

Etymology. I take great pleasure in naming this snake for my friend Dr. Erik Mattison, who has generously supported my research in New Guinea.

Distribution. Known only from mid-elevations on the north slope of Mt. Simpson between 1300–1490 m a.s.l., Milne Bay Province, Papua New Guinea ( Fig. 3 ). Likely to occur across the Mt. Simpson massif at similar elevations.

Ecological Notes. Most animals were brought in by local villagers who obtained them while gardening near Bunisi and Siyomu ( Fig. 4a ), but BPBM 18164 came from primary rainforest above Bunisi ( Fig. 4b ). The species clearly has a broad habitat tolerance and seemed common, given the rate at which animals were obtained (seven animals in four days). It is unknown whether the animals were active or sheltering when collected during the day.

Figures

FIGURE 1. (A) Lateral, and (B) dorsal views of the holotype of Toxicocalamus mattisoni sp. nov. (BPBM 17988). Scale bar = 1 cm.

FIGURE 2. Portrait of head and body of the holotype (BPBM 17988) of Toxicocalamus mattisoni sp. nov. in life.

FIGURE 3. Map of southeastern New Guinea, showing the type locality for Toxicocalamus mattisoni sp. nov. (star) and localities for its putative close relatives: T. loriae (circles), T. mintoni (triangle), T. nigrescens (diamonds), T. pachysomus (square), and T. “loriae” Clade 4 (hexagon) Contours are white <1000 m, pale gray 1000–1500 m, medium gray 1500–2000 m, and dark gray>2000 m.

FIGURE 4. Habitats of Toxicocalamus mattisoni sp. nov. (A) View of Bunisi, showing the cleared grasslands and gardens near the village, with forest farther afield; and (B) view of Mt. Simpson (right), showing a cleared garden area in the foreground; Camp 2 was in the forest several dozen meters to the left of this photo.