Prosymna lisima, Conradie & Keates & Baptista & Lobón-Rovira, 2022

Conradie, Werner, Keates, Chad, Baptista, Ninda L. & Lobon-Rovira, Javier, 2022, Taxonomical review of Prosymna angolensis Boulenger, 1915 (Elapoidea, Prosymnidae) with the description of two new species, ZooKeys 1121, pp. 97-143 : 97

Prosymna lisima sp. nov.

Figs 5 , 7 , 8 , 9 , 11 , 12 Common names: Kalahari Shovel-snout snake (English); Cobra-de-focinho-de-pá-do-kalahari (Portuguese).

Chresonymy.

Prosymna angolensis : Broadley 1971: 82, 1980: 512 (in part); Broadley et al. 2003: 187 (in part); Pietersen et al. 2021: 97, fig.; Conradie et al. 2021: 265.

Material examined.

Holotype (male). PEM R23512 , collected from Cuito River source lake (-12.68866, 18.36025, 1426 m a.s.l.), Moxico Province, Angola by Werner Conradie and James Harvey on 26 November 2016 . Paratypes (five males). PEM R27381 , collected from Quembo River lower bridge (-13.526579, 19.278096, 1248 m a.s.l.), Moxico Province, Angola by Werner Conradie, Chad Keates and Timóteo Júlio on 27 November 2019 ; PEM R23457 -8, collected from Quembo River source (-13.13586, 19.04709, 1368 m a.s.l.), Moxico Province, Angola by Werner Conradie on 3 November 2016 ; PEM R23483 , Cuando River source (-13.00164, 19.1296, 1372 m a.s.l.) Moxico Province, Angola by Werner Conradie and James Harvey on 17 November 2016 ; PEM R23510 , collected from Cuito River source lake (-12.68866, 18.36025, 1426 m a.s.l.), Moxico Province, Angola by Werner Conradie and James Harvey on 26 November 2016 . Paratypes (two females). PEM R23456 , collected from Quembo River source (-13.13586, 19.04709, 1368 m a.s.l.), Moxico Province, Angola by Werner Conradie on 3 November 2016 ; PEM R23511 , Cuito River source lake (-12.68866, 18.36025, 1426 m a.s.l.), Moxico Province, Angola by Werner Conradie and James Harvey on 26 November 2016 .

Additional material assigned to the new species.

NMZB-UM 10096, Kalabo (approx. -14.99391, 22.67795), Zambia; NMZB-UM 21272, 15 km WSW of Katima Mulilo (approx. -17.61448, 24.20593), Namibia. A specimen from Kuvangu [= Vila-da-Ponte], -14.46667, 16.3000 ( Monard 1937: 123) has two postoculars and the characteristic confluent blotched dorsal pattern and might belong to this new species, but this needs verification and is thus tentatively referred to the new species .

Diagnosis.

The new species differs from other Prosymna in the following characters: rostral sharply depressed and angular (vs. rounded in P. visseri ); presences of a single band-like internasals (vs. paired internasals in P. somalica , P. bivittata , P. sudevalli , P. lineata ); dorsal scales smooth (keeled in P. janii ); midbody scale rows 15-17 (vs. 19-21 in P. pitmani ); 6 supralabials, with 3rd and 4th entering orbit (vs. 5 supralabials, with 2nd and 3rd entering orbit in P. meleagris and P. greigerti ); single apical pits on dorsal scales (vs. paired apical pits in P. ruspolii ); lower number of ventral scales in both sexes (116-129 vs. 153-199 in P. frontalis ); dorsum with dark black spots (vs. scarlet head and dark body in P. ornatissima ; uniform dark brown to grey in P. ambigua and P. stuhlmanni ). It further differs from its closest congener, P. angolensis , in having two post oculars (vs. one), dorsal large black blotches mostly fused (vs. mostly small paired dorsal grey to black spots), postorbital bone present (vs. absent) and by the presence of four to five well-developed palatine teeth (vs. three reduced teeth).

Etymology.

The name lisima is derived from the locally spoken Luchaze language in the region of the type locality meaning ‘source’. The full phrase used, ' Lisima Lwa Mwondo ', is translated as "source of life". This is a reference to central Angola, a high rainfall area where some of the most important rivers in Angola arise. This water makes it its way to the Okavango Delta, sustaining wildlife and local communities in Angola, Namibia and Botswana.

Description of holotype

(Fig. 11 ). See Table 4 for further details and meristic data for the holotype. The body is cylindrical and elongated, tapering gradually to a very short tail, 13% total length, tail tip with a prominent spike. Dorsal scales smooth with single apical pits (some suprasubcaudal scales have two apical pits) in 17-15-15 scale rows, scale row reduction from 17 to 16 take place at ventral number 17 with the fusion of 3rd and 4th dorsal scale rows on left side and from 16 to 15 at ventral 23 with the fusion of 3rd and 4th dorsal scale rows on right side; 122 ventral scales; cloaca entire; 13 paired subcaudal scales. Head in dorsal view (Fig. 11B ): head narrow and rounded, barely wider than ‘neck’; rostral clearly visible from above, much broader than long (3.39 × 1.06 mm); a single narrow internasal, which is much longer than wide (2.73 × 0.67 mm) and in broad contact with the rostral anteriorly, posteriorly in broad contact with prefrontal and laterally with nasals; single band-like prefrontal which is longer than wide (3.70 × 1.30 mm), in contact laterally with loreal, and posteriorly with the frontal and supraocular scales; frontal pentangular, almost as long as wide (3.09 × 3.00 mm), nearly equal distance to snout (3.30 mm), shorter than prefrontals (3.0 vs. 3.70 mm), but nearly equal in length to the parietal scales (3.00 vs. 3.04 mm), in contact laterally with narrow supraoculars, and posteriorly with two very large parietals; paired parietals as wide as long (3.04 × 3.04 mm), in contact posteriorly with each other and laterally with temporals. Head in ventral view (Fig. 11C ): rostral clearly visible from below, protruding well past jawline; mental small, triangular; infralabials seven, first three in contact with single paired chin shields, 1st infralabials in contact with each other; additional three or four rows of smaller gular scales present before start of ventral scales. Head in lateral view (Fig. 11D ): snout sharply pointed, longer than the horizontal diameter of eye (ED/SL = 0.49); rostral large with acutely horizontal angular edge, excavated below; nostril is oval shaped, piercing a fully-divided nasal, and directed backwards; nasal scale longer than wide, with anterior part in full contact with rostral, posterior lower corner in contact with 1st supralabial and above with internasal scale and prefrontal; nasal suture present and intersecting 1st supralabial in uppermost corner; single small loreal as long as wide (0.7 × 0.7 mm), in contact below with 1st and 2nd supralabial, above with prefrontal, anteriorly with nasal and posteriorly with single preocular; a single preocular on the right side and two on the left side in contact anteriorly with loreal and prefrontal and above with supraocular, posteriorly protruding of loreal overlap with preoculars to create a small flap; eye large 19.36% headlight, vertical diameter (1.47 mm) two thirds as deep as distance between eye and lip (0.99 mm); pupil round; two postoculars, the lower one largest and in contact with 4th and 5th supralabials, first temporal scale and parietal, the upper smaller in contact with both supraocular and parietal; temporals 1+2 on both sides; narrow elongated supraocular in contact anteriorly with preocular, posteriorly with upper postocular and parietal and above with frontal; six supralabials, 3rd and 4th contacting eye, 5th and 6th supralabial the largest.

Colouration. In life (Figs 5C , 11B-D ). Dorsum bright yellow-brown with 27 irregular fused black blotches that extend along the back from the nape onto the tail. Each dorsal scale has a darker edge giving it a faint reticulated pattern. Dorsolaterally, between the black vertebral blotches, there is a cluster of 2-4 scales with black edges. The large black nape blotch originates at the posterior margin of the frontal and runs through the parietal onto the dorsal scales, and is approximately nine scale rows deep and eleven scale rows wide. Each vertebral black blotch varies from 4-8 scale rows deep and 3-7 scale row wide. Some of the blotches are fused to form a continuous zig-zag pattern. Frontal and prefrontal sutures have a dark edge forming a pale grey crossbar. Eyes black. Ventrum cream-white, with the two outermost dorsal scale rows same colour as ventrum. In preservative (Fig. 11A ). Same as in life, but yellow-brown colouration faded and the dark edges became more noticeable. Ventrum beige.

Paratype and additional material variation. See Table 2 and 4 for full meristic data. Dorsal scales smooth and in 17-17-15 rows at midbody; 116-124 (116-124 males, 117-129 females) smooth ventral scales; 18-26 (22-26 males, 18-24 females) paired subcaudal scales; one (rarely two) preoculars; two postoculars; temporals mostly 1+2; mostly six supralabials, with 3rd and 4th entering the orbit; seven infralabials, with first three in contact with the chin shield, cloacal scale entire; 21-36 fused dark dorsal spots. Largest female: 275+28 mm (NMZ UM 21272: 15 km WSW of Katima Mulilo); largest male: 198+25 mm (PEM R23458: Quembo River source). The colouration of the type material is in general in agreement with the holotype, except that the dorsal fused blotches vary in size, number and arrangement (Fig. 5A-C ). The nape black blotch always originates at the anterior part of the frontal extending through the parietals to 7-9 dorsal scale rows deep, 11-15 scales wide and start from the 3rd-5th lateral dorsal scale row. The dorsum consists of 21-36 confluent black blotches that are 7-11 scales wide and three to four scales deep. One specimen (PEM R23456) exhibits a distinct dark interorbital band and internasal band. The only juvenile collected (PEM R27381, Fig. 5C ) has small paired black blotches (two scales deep and four scales wide) on a lighter yellow ground colour, large head blotch starts at posterior frontal through parietals, seven scales wide.

Skull osteology and teeth (Figs 7 - 9 ). This species presents a compact and rigid skull, common among Prosymna species with unfused braincase and nasal bones. Parietals are fused. Postorbital bone is present and contributes to the posterior edge of the orbital rim. Premaxilla has a short but robust ascending nasal process that lies between the ventral laminae of the nasals with low profile of the anterior portion which gradually slope ending in a moderate narrow tip and two elongated maxillary processes. Maxilla and premaxilla are in contact. Nasal bones are medium large bones in contact with frontal and premaxilla. Septomaxilla is a well-developed bone, in broad contact with the premaxilla, frontal, vomer, prefrontal and frontal bones. Vomer is well developed with a perforated dorsolateral portion. Maxillary is reduced anteriorly with an elongated pick-shaped palatine process with five or six laterally reduced curved tooth loci, followed by four to five enlarged lancet-shaped tooth loci, on same disposition. Palatine with four to five well developed teeth and an enlarged dorsal curved vomerine process. Pterygoid is a thin elongated bone. Supratemporal is in broad contact with the quadrate and participates in the lateral movement of the lower jaw. The lower jaw presents a compound bone, splenial, coronoid and dentary. Coronoid and splenial are reduced, almost vestigial. Dentary with eight tooth loci.

Hemipenis . Short simple structure, only reaching the 6-9th ventral scale. Single non-bifurcated sulcus. Ornamentation is flounced. Proximal third is smooth. Distal portion with four to five flounces that starts at the sulcal fold and encircle the whole organ, the most proximal often branched, forming a pocket of which the edges is smooth, tapering into a distal point. Retractor muscle is straight.

Natural history notes.

All specimens were caught in late November during the rainy season. At this time, many adult lacertids, Ichnotropis capensis and I. cf. grandiceps , were also observed mating in the same habitat. Prosymna are well known to prey on soft-shell lizard eggs, and P. lisima sp. nov. may actively seek out these lacertids’ eggs. Only two of the females had stomach contents, while all the males had empty stomachs. The largest female (PEM R23456) had three empty lizard egg shells in the hind gut, three empty egg shells at the rear end of the stomach, and four undigested lizard eggs in the main stomach (Fig. 12 ). Another female (PEM R23511) had four undigested lizard eggs in the main stomach. All eggs measured ~ 11.0 mm in length and each had a lateral cut. The eggs in the main stomach also all had a lateral cut but still maintained their shape and were surrounded by calcified leaked yolk (due to the preservation process). The eggs at the rear and the hindgut were all undecomposed and compressed. One of the paratype females (PEM R23456) was gravid, and had three eggs in early developmental stages (16.8 × 4.2 mm). Interestingly, on two different occasions, three specimens (two males and one female) were caught on the same night in the same trap array. This may indicate that males were following females to breed.

Distribution and habitat.

Currently only known from east-central Angola, western Zambia and the Zambezi Region of north-eastern Namibia. In the region of Katima Mulilo (eastern Zambezi Region, Namibia) it occurs in sympatry with its sister species, P. angolensis (Fig. 2 ). The tentative assigned material from Kuvango ( Monard 1931) needs verification, but it agrees in colouration and morphology to the new species. This species is expected to be much more widely distributed in the Kalahari basin, as it seems to be associated with the deep Kalahari sands. The Angolan material occurs in Angolan moist miombo woodland, while the Zambian and Namibian material occurs in dry miombo woodland. The elevation ranges between 950 and 1450 m a.s.l. All newly collected specimens were captured in trap arrays set in sandy areas next to river source lakes or main rivers in eastern Angola ( Conradie et al. 2021).

Figures

Figure 2. a Maximum likelihood (IQTREE) concatenated phylogeny with BI BEAST and BI MrBayes support overlain. Each of the species groups are demarcated by coloured vertical bars at the right margin b maximum likelihood (IQTREE) phylogenies (16 S and cyt-b) with gene-specific single-locus species delimitation analyses results overlain. The bars to the right of the phylogeny represent the putative taxa assignments for each analysis and the values beneath the bars denote the total number of putative taxa for each analysis.

Figure 5. Photos of live P. lisima sp. nov. from eastern Angola A PEM R 23457 from Quembo River Source, Moxico Province, Angola B PEM R 23483 from Cuando River Source, Moxico Province, Angola C PEM R 23512 from Cuito Source Lake, Moxico Province, Angola D PEM R 27381 from Quembo River bridge camp, Moxico Province, Angola.

Figure 7. A Lateral B ventral C medial D dorsal views of skulls of Prosymna angolensis subgroup. Red arrows depict variation characters between the P. lisima sp. nov., P. angolensis, P. confusa sp. nov., P. cf. frontalis, and P. janii.

Figure 8. A Frontal and B posterior views of skulls, and C lateral, dorsal, medial and ventral view of jaw of Prosymna angolensis subgroup. Red arrows depict variation in characters between the P. lisima sp. nov., P. angolensis, P. confusa sp. nov., P. cf. frontalis, and P. janii.

Figure 9. A Dorsal, frontal and ventral view of premaxillae B medial, posterior and dorsal views of palatine; and C lateral, dorsal, and ventral view of maxilla in P. lisima sp. nov., P. angolensis, P. confusa sp. nov., P. cf. frontalis and P. janii (from left to right).

Figure 11. Holotype of Prosymna lisima sp. nov. (PEM R 23512) from Cuito River source, Moxico Province, Angola A dorsal and ventral full body B dorsal head C ventral head D lateral head.

Figure 12. Stomach and gut contents of Prosymna lisima sp. nov. (PEM R 23456) consisting of lizard egg shells. Scale bar: 1 mm.