Phalotris shawnella, Smith & Brouard & Cacciali, 2022

Smith, Paul, Brouard, Jean-Paul & Cacciali, Pier, 2022, A new species of Phalotris (Serpentes, Colubridae, Elapomorphini) from Paraguay, Zoosystematics and Evolution 98 (1), pp. 77-85 : 77

Phalotris shawnella sp. nov.

Type locality.

Rancho Laguna Blanca, Departamento San Pedro, Paraguay (Fig. 1 ).

Holotype.

CZPLT-H-594; adult male; collected during digging on 3 January 2014 (J-P. Brouard); Rancho Laguna Blanca, 23°48'43"S, 56°17'49"W (WGS 84), 204 masl, San Pedro department. Specimen complete but damaged during collection, being severed approximately at mid-body (Fig. 2 ).

Diagnosis.

Phalotris shawnella sp. nov. is assigned to the Phalotris nasutus group on account of the pointed snout with prominent rostral shield and the fusion of the second and third temporal plates (Fig. 3A ). The new species can be distinguished from all other members of the Phalotris nasutus group by the combination of the following characters: 1) fifth supralabial in contact with parietal, 2) vertebral stripe present, 3) yellowish nuchal collar (2 or 3 dorsal scales long), 4) dull reddish color of head in adults, 5) broad, solidly or near solidly dark lateral bands, 6) red-orange ventral scales lightly and irregularly spotted with black, mainly on the posterior half of the body, and 7) a bilobed, extremely asymmetrical hemipenis, with enlarged, curved, lateral spines.

Phalotris shawnella sp. nov. is differentiated from the individual members of the Phalotris nasutus group and the only species known to occur sympatrically with it ( P. multipunctatus ) as follows. (The characteristics of Phalotris shawnella sp. nov. are given first, followed by the comparison species in parentheses):

Phalotris nasutus Gomes, 1915: 1) broad black lateral bands running the length of the body (absent in P. nasutus or present vestigially on the posterior part of the body only); 2) supralabial concolorous with head (supralabials paler than head); 3) ventral coloration red-orange with blackish smudges on the lateral part of the ventral scales, and scattered larger irregular black blotches (ventral immaculate pink); 4) ventral scales 185 in the male (ventrals in males < 182); 5) hemipenis bilobed and greatly asymmetrical (hemipenis only slightly asymmetrical).

Phalotris lativittatus Ferrarezzi, 1993. Superficially closest to this species within the Phalotris nasutus group, which shows little variation in appearance across the large range and specimen series available (H. Braz in litt.). It can be reliably distinguished from P. shawnella sp. nov. with the following characters: 1) Supralabials uniformly brownish red (supralabials pale in P. lativittatus ); 2) infralabials uniformly grey (infralabials with some dark markings); 3) scattered dark spots along the sides of the ventral scales (uniform pale ventral scales); 4) broad lateral band solid or nearly solid (lateral band with broad pale scale edges along entire length); 5) small spines at the lower part of the hemipenis (larger spines all along the body of the hemipenis).

Phalotris nigrilatus Ferrarezzi, 1993. Geographically, this is the only species that approaches P. shawnella sp. nov. within the Phalotris nasutus group and is the only species with which it shares two key characters: a solid dark lateral band and dark markings on the ventral scales. Phalotris nigrilatus is otherwise phenotypically strikingly different and the significant specimen series now available indicates that it is morphologically very conservative ( Cacciali et al. 2020). 1) Presence of clear pale collar (absence of collar in P. nigrilatus ); 2) Ventral dark markings irregular, diffuse and widely-spaced, mainly on the posterior half of the body (ventral dark markings dense and typically regular, at the edges of each ventral scale and along the entire underside); 3) Chinshields pale contrasting with dark infralabials (chinshields dark, not contrasting with infralabials); 4) Head brick red dorsally with brownish suffusions in adult (head black in adult); 5) thin spines on the hemipenis (thick spines).

Phalotris concolor Ferrarezzi, 1993: 1) fifth supralabial in contact with parietal (separated in P. concolor ); 2) presence of broad dark lateral band (lateral coloration uniformly red); 3) indistinct black vertebral line (dorsal coloration uniformly red); 4) ventral scales 185 in the male (212 ventral scales in the only male known).

Phalotris labiomaculatus Lema, 2002. 1) Supralabials uniformly brownish-red, concolorous with rest of head (spotted black and white supralabials in P. labiomaculatus ); 2) wide dark lateral band (body coloration uniformly orange with no dark lateral band); 3) yellow nuchal collar 2-3 scales wide (white nuchal collar 3-4 scales wide); 4) dark vertebral line present (no vertebral line); 5) irregular dark spots on the ventral scales (uniformly white ventral scales).

Phalotris multipunctatus Puorto & Ferrarezzi, 1993. This is the only species of Phalotris known to occur sympatrically with P. shawnella . 1) Scales of broad lateral bands lacking white spotted pattern (scales of broad lateral bands with white tips giving spotted pattern in P. multipunctatus ); 2) red-orange ventral scales lightly and irregularly spotted with black, mainly on the posterior half of the body (ventral scales black with broad white posterior edges forming banded pattern); 3) head brick red (in adult) or black (in juvenile) lacking any white spotting (head black with profuse white spotting); 4) infralabials uniform (each infralabial with a single large white medial spot); 5) longitudinal dark mid-dorsal stripe present (longitudinal dark mid-dorsal stripe absent).

Description of holotype.

An adult male in two pieces, SVL 260 + 140 (=400) mm; TL 65 mm (16.25% of SVL); one preocular, two postoculars; temporals 0+1/0+1; loreal absent; supralabials 6(2-3)/6(2-3), fifth supralabial broadly contacts parietal; infralabials 7(1-5)/7(1-5), 1st to 4th contacting the anterior pair of chinshields and 4th to 5th contacting the posterior pair of chinshields; posterior chinshields longer and thinner than anterior chinshields; dorsal scale rows 15-15-15; scales smooth lacking apical pits; 185 ventrals; anal plate divided; 35 paired subcaudals. Yellow nuchal collar two to three scales wide and posterior black collar one to two scales wide. Slight trace of incomplete anterior black collar, most evident laterally. Rostral prominent and wider than it is long (1.9 × 2.6 mm); nasal complete, twice as long as greatest width (2.2 × 1.1 mm), contacting the rostral anteriorly, the 1st and 2nd supralabial ventrally, the preocular posteriorly, and the internasal and frontal dorsally; paired internasals slightly wider than they are long (1.4 × 2.2 mm); the second temporal longer than wide (3.1 × 1.4 mm); preocular longer than wide (1.3 × 0.9 mm), contacting 2nd supralabial; two postoculars as long as wide (approximately 0.6 × 0.6 mm), the lower postocular contacting the 3rd to 5th supralabials and only slightly smaller than the upper; single prefrontal twice as wide as long (2.3 × 4.2 mm); supraocular twice as long as wide (2.2 × 1.2 mm); frontals slightly longer than they are wide (3.6 × 2.8 mm); paired parietals twice as long as wide (6.0 × 3.1 mm). No differences in shape in right/left sides. Eye diameter 1.1 mm.

Hemipenis morphology.

Semicalyculate and semicapitate (Fig. 4 ). Long, slender and bilobed, distinctly asymmetrical (right lobe -from asulcate view- 2/3 shorter), with enlarged, curved, lateral spines (13 to 15 large spines on each side). Sulcus furcation located in basal third and branches centrolinear. Note that right lobe (from asulcate view) is not fully everted, missing ca. 1 mm.

Color in life.

Head brick red dorsally, with slightly darker suffusions, and uniformly brownish red on supralabials; red-orange ventrally with a greyish tinge to the first three infralabials, and whitish chin shields. A single row of scales on the posterior part of the dorsal surface of the head shows traces of a faint black anterior collar, mainly laterally. A broad yellow collar fades laterally and is followed by a thinner black collar (Fig. 3B ). Neither collar is visible ventrally. Body coloration brick red dorsally, with a faint trace of a thin black vertebral line formed by a small dark spot anteriorly on each vertebral scale connected by a thinner black streak along the center of the scale that is variably conspicuous along the length of the body and fades out upon reaching the tail. Broad black (to brownish-black) lateral lines running the length of the body from the posterior black collar to the tip of the tail. Lateral bands uniformly 3-3.5 scales wide over the entire length of the body, narrowing only slightly to 2 scales width on the tail. Ventrally red-orange, the edges of some of the ventral scales with small black, diffuse blotches (more prominent on the posterior ventral scales). Medial parts of the ventral scales are largely uniform apart from a very small number of often large black smudges, irregularly dispersed on the midbody region.

Color in preservative.

Head fades to dull brownish (Fig. 2 ). Yellow collar to pinkish white. Black lateral and vertebral lines dark blackish-brown. Brick red of dorsum fades to brownish. Ventrally, the coloration is creamy-white, slightly yellower medially on the ventral scales and towards the tail, whiter laterally on the ventral scales and towards the head.

Variation.

Described on the basis of an individual captured (on 9 December 2013) close to the collection locality of the holotype, which was photographed (Fig. 3C ) and which later escaped. This individual was smaller and presumed to be juvenile female (weight 7 g), SVL 250 mm, TL 20 mm. It initially showed extensive black coloration on the head, broadly suffused with brick red dorsally, but the red areas became more prominent over its few months in captivity - a possible ontogenic change. The yellow nuchal collar was broader (3 to 4 scales wide) and paler, being creamy yellow as opposed to orange-yellow. The posterior black nuchal collar was absent dorsally, with the black mid-dorsal line forming a broad, smudgy spot covering an entire scale where it contacted the yellow nuchal collar, and bordered either side by a single orange scale between it and the black lateral bands. Dorsally, it was a deeper red, and ventrally it was a deeper orange-red, than the holotype. Dorsals 15-15-15, ventrals 197, subcaudals 26 (divided), temporals 0+1/0+1. Additional images of the known specimens are stored in FigShare (https://doi.org/10.6084/m9.figshare.c.5804246.v1).

Etymology.

The species name is a combination of the first names of two remarkable young people who were born around the same time as Fundación Para La Tierra, and who inspired its founders to work towards the study and conservation of the Paraguayan fauna, so that one day they might inherit a better world: Shawn Ariel Smith Fernández and Ella Bethany Atkinson. The epithet is not Latin, is invariable (word in apposition) and is made up of elements of both of their names.

Ecology.

The holotype was collected by day in Cerradón forest on a sandy substrate, close to disturbed bushy Cerrado and within 500 m of a lake shore (Fig. 5 ). The topotype (juvenile female) was kept in captivity for ecological observations, but unfortunately later escaped. Nine days after capture (on 18 December 2013) it was offered a Gymnophthalmid lizard ( Vanzosaura rubricauda ) with 0.7 g mass and 55 mm total length, which it had consumed by the following day. On 22 December 2013 it was offered another V. rubricauda , of similar size, and by the next day the tail of the lizard was missing; it later consumed the rest of the lizard on 25 December 2013. Two days later, the snake drank water.

A third individual showing the clear diagnostic characters of this species (Fig. 3D ) was photographed in leaf litter 500 m outside of the settlement of Colonia Volendam (24°16'28.6"S, 57°01'25.3"W), San Pedro department (Fig. 1 ) by Marko Fast on 10 March 2019, at 13:36 h, in a small patch (0.29 km2) of degraded Cerradón forest. When encountered, the individual had both the head and tail hidden under the leaf litter. The specimen did not show any aggressive behavior, and was released after being photographed.

Figures

Figure 1. Known localities for Phalotris shawnella sp. nov. in San Pedro department, Paraguay Square: type locality. Circle: additional locality at Colonia Volendam.

Figure 2. Dorsal (left) and ventral (right) overviews of the holotype of P. shawnella sp. nov. The specimen was accidentally severed during collection. Scale bar: 2 cm. (Photograph by Jeremy Dickens).

Figure 3. Coloration in life of P. shawnella sp. nov. A. Detail of the head of the holotype (CZPLT-H- 594); B. Dorsolateral view of the holotype; C. Juvenile topotype specimen, kept in captivity and which later escaped; D. Live specimen photographed at Colonia Volendam. (A-C photographed by Jean-Paul Brouard, D photographed by Marko Fast).

Figure 4. Hemipenis of P. shawnella showing the asulcate (left) and sulcate (right) views. Gray bar = 3 mm. (Photograph by Paul Smith).

Figure 5. Collection locality of holotype, Rancho Laguna Blanca, San Pedro department, Paraguay. (Photograph by Para La Tierra).