Potamites hydroimperator, Chávez & Malqui & Catenazzi, 2021

Chávez, Germán, Malqui, Jose & Catenazzi, Alessandro, 2021, A new riparian Andean Potamites (Reptilia, Squamata, Gymnophtalmidae) from El Sira Mountains, central Peru, with comments on P. ecpleopus Cope 1875, and on the taxonomy and biogeography of Potamites, European Journal of Taxonomy 760, pp. 136-159 : 140-147

Potamites hydroimperator sp. nov.

urn:lsid:zoobank.org:act:2BA679E8-0E9B-496C-A03A-0C9C84DDD958

Figs 2–3 , 4A–B , 5A–B , 7A , 8A ; Table 1

Potamites ecpleopus – Torres-Carvajal et al. 2016: 70. See comments under ʻGeneric allocationʼ.

Diagnosis

A medium-sized Potamites (SVL = 50.5–59.6 mm, n = 5) characterized by the following combination of morphological features: 1) Body slender, slightly depressed laterally, maximum SVL in males 59.6 mm, 51.6 mm in females; 2) head acuminate from dorsal and lateral view, scales on the dorsal surface of the head smooth; 3) frontonasal divided, shorter than frontal, small rounded azygous scale usually present between frontonasal and prefrontals; 4) prefrontals present; 5) frontal present; 6) loreal present, romboid, not in contact with supralabials; 7) nasal partially divided, behind the nostril; 8) supraoculars four, anteriormost not fused with anteriormost superciliar; 9) superciliar series complete, usually five, occasionally four; 10) supralabial-subocular fusion absent; 11) lower palpebral disc oval, transparent, not divided; 12) postoculars three; 13) postparietals 10–11; 14) hemipenis in two pairs, transverse sutures perpendicular with respect to midline of body; 15) dorsals rectangular, subimbricate, granular and keeled; 16) 34–36 longitudinal rows of dorsal keeled scales, 2–3 granular scales between the two paravertebral rows of keeled dorsals; 17) flanks partially covered by subconical low tubercles, absent or poorly present above the insertion of forelimbs; 18) anterolateral and dorsal brachial scales of forelimbs smooth or slightly keeled; 19) 32–36 scales around midbody; 20) 21–22 longitudinal rows of ventral scales; 21) 32– 33 total femoral pores in males, two in females, two scales between femoral pores; 22) 14–16 subdigital scales on 4 th finger; 23) 21–24 on 4 th toe; 24) forelimb reaching anteriorly the fourth supralabial; 25) tail slightly compressed with three rows of lateral scales per two ventral caudals; 26) hemipenis globose (Supp. file 5), lobes indistinct from hemipenial body; 27) hemipenial flounces chevron shaped, lacking calcified spines, laterally oriented and forming two chevrons on distal half of hemipenis while its basal half is covered with four transverse flounces, separated by a small expansion pleat; sulcate flounces about as wide as asulcate flounces; isolated transversal flounces on proximal-central region of asulcate face absent; distal filiform appendages on the hemipenial lobes absent, sulcus spermaticus single; 28) dorsum yellowish brown to dark brown with slightly darker irregular blotches; 5–8 lateral ocelli with a creamy yellow center on each flank in males, a single ocellus with a pale brown center at the level of the insertion of forelimbs on each flank in females; flanks yellowish brown or partially pigmented of vermilion red in adult males; a creamy white to yellow diagonal stripe (continuous or discontinuous) going from 4 th or 5 th supralabials to 5 th infralabial; ventral coloration in males vermilion red to reddish pink on belly and base of the tail, yellowish pink on ventral surface on limbs, pale blue to grayish blue on ventral surface of the neck and throat, saffron yellow on femoral pores; ventral coloration in females creamy yellow on throat, chest, belly, ventral surface of limbs and base of the tail, with black speckling on throat; ventral surface of the rest of the tail yellowish brown to dark brown in males and females; pupil black surrounded by a yellowish orange to copper ring, iris olive to yellowish brown.

Differential diagnosis

The presence of longitudinal dorsal rows of keeled scales makes Potamites hydroimperator sp. nov. similar in appearance to populations of P. ecpleopus , a species widely distributed along the eastern Andean foothills and the Amazon ( Uzzell 1966; Avila-Pires 1995; Ribeiro-Júnior & Amaral 2016, 2017). Potamites hydroimperator sp. nov. can be distinguished from P. ecpleopus (characters for P. ecpleopus in parenthesis) by having low tubercles on flanks and above forelimbs (vs flanks strongly tuberculate, see Fig. 8A–C ), anterodorsal region of forelimbs smooth or slightly keeled (vs strongly keeled, see Fig. 8A–C ), 4–5 superciliars (vs 3–4, see Fig. 4A, C ), a smaller size with males reaching a maximum SVL of 59.6 mm (vs 64.0 mm, except for the Ucayali Valley population, where males reach 58.0 mm), and the presence of 5–8 pairs of conspicuous lateral ocelli in males (vs 1–5 pairs of conspicuous lateral ocelli). The new species is easily distinguishable from P. erythrocularis , P. montanicola , P. ocellatus , and P. trachodus ( Figs 5 , 7 ), all of them inhabiting the Andean foothills and montane forests, by having longitudinal rows of keeled scales on dorsum (vs scattered or irregular rows of keeled scales), and males with 5–8 lateral ocelli on each flank (vs 1–5). Potamites hydroimperator sp. nov. shares with P. juruazensis the presence of an azygous scale behind frontonasal in the most of individuals ( Fig. 4B, H ), but is easily differentiable by having a larger SVL reaching 59.6 mm in males (vs 50 mm), an acuminate head from lateral view (vs rounded), a longer count of total femoral pores, 32–33 in males and two in females (vs 10–16 in males, 0–1 in females), numerous lateral ocelli in males and females (vs absent), and absence of small scales between frontal and frontoparietals (vs two or three small scales, see Fig. 4B, H ). Finally, P. hydroimperator sp. nov. differs from P. stangulatus by having rows of keeled scales on neck and dorsum (vs low not keeled dorsal scales, see Fig. 5A–B, K–L ), a smaller count of transverse rows of dorsals with 34–36 (vs 55–90), and by having a smaller number of total femoral pores, 32–33 in males and two in females (vs 54–55 in males, 6–10 in females).

Etymology

The specific epithet ʻ hydroimperator ʼ derives from the Greek word ʻhydroʼ (ʻwaterʼ), and the Latin name ʻimperatorʼ (ʻemperorʼ). The name alludes to the riparian habits of the new species, which is the only lizard in El Sira using the streams as part of its habitat.

Material examined

Holotype PERU • adult ♂; Departamento de Huánuco, Puerto Inca Province, El Sira Communal Reserve, Campamento Hospital (on the trail to the top of El Sira Communal Reserve); 9.478667° S, 74.778139° W; 757 m a.s.l.; 28 Nov. 2013; G. Chávez leg.; CORBIDI 13915 ( Figs 2 , 4A–B , 7A ).

Paratypes (n = 4) PERU • 1 adult ♀; same locality data as for holotype; 21 Mar. 2014; G. Chávez and J. Malqui leg.; Genbank accession code KU902066 ; CORBIDI 14382 • 2 adult ♂♂; Departamento de Huánuco, Puerto Inca Province, El Sira Communal Reserve, Campamento Caoba (on the trail to the top of El Sira Communal Reserve); 9.502194° S, 74. 80425° W; 545 m a.s.l.; 28 Mar. 2014; G. Chávez and J. Malqui leg.; CORBIDI 14468 to 14469 ( Figs 3A–D , 5A–B ) • 1 adult ♀; same collection data as for preceding; CORBIDI 14470 ( Fig. 3E–F ) .

Description (holotype)

The holotype is adult male CORBIDI 13915 ( Figs 2 , 4A–B , 7A ). Body long, laterally compressed, SVL 59.4 mm; tail (complete) length 81.7 mm, axilla to groin distance 27.8 mm; head length 16.1 mm; head width 10.0 mm; shank length 9.7 mm. Head scales smooth; rostral scale wider (2.2 mm) than long (1.1 mm), higher than adjacent supralabials, in contact with frontonasal, nasal, and first supralabials posteriorly; frontonasal divided, almost squarish, slightly wider (2.2 mm) than longer (2.1 mm), widest posteriorly, in contact with nasoloreal and frenocular laterally, and azygous scale and prefrontals posteriorly; azygous scale between frontonasal and prefrontals rhomboid, about four times smaller than frontonasal, in contact anteriorly with posterior edge of frontonasal and posteriorly with anterior edge of prefrontals; nasal almost triangular, apex in contact with rostral, nasoloreal suture present, incomplete; prefrontals present, in contact with each other medially, in contact with anteriormost superciliary and anteriormost supraocular, frontal posteriorly; frontal longer (3.1 mm) than wider (1.9 mm), anterior suture angular with point directed anteriorly, lateral sutures straight, posterior suture angular with point slightly directed posteriorly, in contact with first, second, and third supraocular laterally, frontoparietals posteriorly; frontoparietals pentagonal, in contact with third and fourth supraocular, parietals and interparietal posteriorly; supraoculars four, none in contact with ciliaries; superciliary series complete, five, anteriormost superciliary not fused with anteriormost supraocular; interparietal pentagonal, slightly longer (3.0 mm) than wider (2.8 mm), in contact with parietals laterally, postparietals posteriorly; parietals pentagonal, in contact with fourth supraocular anterolaterally, dorsalmost postocular, postparietals posteriorly; postparietals 13, polygonal, boardering parietals and interparietal; palpebral disc an undivided oval, unpigmented; loreal rhomboid, not in contact with supralabials; frenocular pentagonal, in contact with nasal anteriorly; postoculars three; temporals polygonal, of a medium size; supralabials six; infralabials five; mental wider (1.9 mm) than long (1.3 mm), in contact with first infralabials, postmental posteriorly; postmental single, slightly wider (2.6 mm) than long (2.5 m), pentagonal, posterior suture angular, point directed posteriorly, in contact with first and second infralabials; genials in two pairs, anterior pair subquadrangular, in contact with second and third infralabials; posterior genials pentangular, in contact with third and fourth infralabials laterally; scale rows between genials and collar fold (along midventral line) 16; posteriormost gular row enfolded posteriorly, concealing two granular scale rows; lateral neck scales rounded, conical. Dorsal scales both granular and keeled, a longitudinal row of dorsolateral tubercle scales on both sides, tubercles posteriorly projected, dorsal keeled scales 35 in a longitudinal count, forming four rows from post occipital region to posterior edge of insertion of hindlimbs, separated by granular scales; lateral scales on body near insertion of forelimb small, conical dorsally, mostly granular; ventrals squarish and juxtaposed; complete longitudinal ventral count 21; longitudinal ventral scale rows at midbody seven; 41 scales around midbody; anterior preanal plate scales two; posterior preanal plate scales three, arranged in a row, central smaller and triangular, pointed posteriorly, in contact distally and posteriorly with scales at both sides, scales at sides hexagonal, larger than central preanal, contacting each other behind central preanal; dorsal and dorsolateral surface of tail with at least 64 whorls of enlarged keeled scales; midventral subcaudals squarish, smooth. Limbs pentadactyl; digits clawed; forelimb reaching anteriorly to fifth infralabial; anterolateral and dorsal brachial scales smooth or slightly keeled, imbricate; midbrachial anterodorsal scale at least twice as large as adjacent scales, slightly keeled; anteroventral, ventral, and posteroventral scales granular, imbricate; antebrachial scales polygonal, slightly keeled; medial antebrachial scales small, polygonal, smooth; dorsal manus scales polygonal, imbricate, smooth; palmar scales small, polygonal, smooth; dorsal scales on fingers smooth, quadrangular, covering dorsal half of digit, overhanging supradigital scales, two on I, seven on II, eight on III, eleven on IV, six on V; subdigital scales 6/5 on I, 11/10 on II, 14/15 on III, 17/16 on IV, nine on V; dorsal thigh scales granular, slightly tuberculate, some scales bearing conical tubercles, anterodorsal thigh scales polygonal, larger than adjacent scales, slightly keeled; posterodorsal thigh scales small, granular, dorsalmost scales slightly tuberculate, arranged irregularly, ventral thigh scales polygonal, smooth, smaller than anterodorsal thigh scales and reducing distally; anterior and anteromedial shank scales granular, imbricate, tuberculate, anteriormost scales at the same size as lateral, posterolateral, and posteromedial shank scales; lateral, posterolateral, and posteromedial shank scales granular, imbricate, some bearing conical tubercle; scales on dorsal surface of digits single, quadrangular, smooth, overhanging supradigital scales, four on I, eight on II, 11/12 on III, 16/17 on IV, 9/10 on V; subdigital scales single or double, 9/10 on I, 10/11 on II, 16/17 on III, 24/25 on IV, 11/12 on V; total femoral pores 33 (17/16). The completely everted hemipenis is an acapitate organ without a medial welt; apex with two large protrusions separated by the distal end of the sulcus spermaticus; sulcus spermaticus single, flounces lacking calcified spines and forming two chevrons on distal half of hemipenis; sulcate flounces about as wide as asulcate flounces; asulcate flounces becoming shorter distally, three in the basal half and sixteen in each protrusion, distal chevrons separated by a small expansion pleat; sulcus spermaticus single, flanked by a broad naked expansion pleat widened distally.

Coloration in life

Dorsal and lateral surfaces of head brown to dark brown ( Fig. 2C ); rostral scale same colour as head; superior labium bluish grey with pale red irregular blotches on third, fourth, and fifth supralabials, irregular vermilion red blotches on sixth and seventh supralabials, an irregular diagonal pale yellow stripe going from fourth supralabial to superior edge of fifth infralabial; infralabials grayish blue, pale red faded blotches on fifth infralabial, and a vermilion red patch on sixth infralabial; iris olive yellow, with a copper orange ring surrounding pupil; throat and gular region greyish blue, darker on ventral surface of neck. Dorsal surface of body yellowish brown, with some darker areas; coloration on flanks yellowish brown with eight black ocelli on both sides, going from neck to base of tail (after insertion of forelimbs), each ocelli bearing a white center; tuberculate scales darker than granular scales; belly vermilion red. Dorsal surface of limbs similar to body, ventral surface of arms and legs pinkish cream; femoral pores saffron yellow. Coloration of dorsal surface of tail like that of body, ventral surface of tail pinkish cream with irregular red blotches at base, and a darker flecking pattern on rest of tail.

Coloration in preservative

General coloration pattern is as described for the holotype in life. Dorsal coloration is mostly brown, with labial region greyish brown, throat yellowish brown, chest dark brown and venter creamy yellow. Flanks yellowish brown, lateral ocelli present. Ventral surfaces of forelimbs pale yellow with black blotches; ventral surfaces of limbs creamy yellow with dark speckling; ventral surface of tail brownish yellow with diffuse dark speckling.

Taxonomic remarks

Females CORBIDI 14382 and 14470 ( Fig. 3 E–F ) have four superciliars. The frontonasal scale is partially divided in male CORBIDI 14469 ( Fig. 3 C–D ). Furthermore, the azygous scale between the frontonasal and prefrontals is absent in male CORBIDI 14469 ( Fig. 3C–D ) and female CORBIDI 14470 ( Fig. 3E– F ). We described colour pattern variation of the type series in the diagnosis. Other measurements and scutellation data of the type series are summarized in Table 1 .

Distribution and ecology

We observed the new species in streams and surrounding vegetation in two nearby sites, in the eastern slopes of the mountains of El Sira Communal Reserve, from 550 to 750 m a.s.l. ( Fig. 1 ). These streams drain into the Pachitea River, which is a tributary of the Ucayali River. The habitat is a montane forest ( Fig. 6 ), with riparian vegetation consisting mainly of bushes, tree ferns and trees canopy ~ 20 m tall. Climbers are also present (lianas) as well as low epiphytes, ferns, mushrooms, and lichens on the ground and on rocks alongside the streams. We found lizards at night by lifting rocks or removing vegetation near stream banks. The male CORBIDI 14468 and the female CORBIDI 14470 used the stream to escape from the field researchers. We observed the new species in sympatry with the lizards Anolis cf. fuscoauratus, Enyaloides laticeps Guichenot, 1855, Iphisa elegans Gray, 1851 , Potamites cf. juruazensis and the snakes Bothrocophias microphtalmus Cope, 1875 , Dipsas catesbyi Sentzen, 1796 , Dipsas pavonina Schlegel, 1837 , and Xenoxybelis argentea Daudin, 1803 . None of these squamates were found in water. On the basis of known diet habits and previous reports ( Dueñas & Valencia 2018), we regard B. microphtalmus as a potential predator of Potamites hydroimperator sp. nov.

Figures

Fig. 2. Holotype in life of Potamites hydroimperator sp. nov., CORBIDI 13915 (SVL = 59.4 mm). A. Dorsal view. B. Ventral view. C. Dorsolateral view of the head.

Fig. 3. Variation of the type series showing the dorsal (left column) and ventral (right column) views of paratypes. A–B. ♂, CORBIDI 14468 (SVL = 54.5). C–D. ♂, CORBIDI 14469 (SVL = 59.6). E–F. ♀, CORBIDI 14470 (SVL = 51.6).

Fig. 4. Lateral (left columns) and dorsal (right columns) views of the head of all species ofPotamites Doan & Castoe, 2005, showing condition of superciliars (turquoise), loreal (purple), frontonasals (yellow), parietals and interparietal (blue), postparietals (red), and azygous scales (green). A–B. P. hydroimperator sp. nov. (CORBIDI 13915, holotype). C–D. P. ecpleopus Cope, 1875 (CORBIDI 9059). E–F. P. erythrocularis Chávez & Catenazzi, 2014 (MUSM 28056, holotype). G–H. P.juruazensis Avila-Pires & Vitt, 2001 (CORBIDI 15504). I–J. P. montanicola Chávez & Vasquez, 2012 (CORBIDI 8322, holotype). K–L. P. ocellatus Sinitsin, 1930 (AMNH 22512, holotype). M–N. P. strangulatus Cope, 1868 (CORBIDI 11415). O–P. P. trachodus Uzzell, 1966 (CORBIDI 15515).

Fig. 5. Coloration in life of males of all species of Potamites Doan & Castoe, 2005 ocurrying in Peru. A–B. P. hydroimperator sp. nov. (CORBIDI 14468). C–D. P. ecpleopus Cope, 1875 (CORBIDI 9516). E–F. P. erythrocularis Chávez & Catenazzi, 2014 (MUSM 30260). G–H. P.juruazensis Avila-Pires & Vitt, 2001 (CORBIDI 15504). I–J. P. montanicola Chávez & Vasquez, 2012 (CORBIDI 10596). K–L. P. strangulatus Cope, 1868 (CORBIDI 11415). M–N. P. trachodus Uzzell, 1966 (CORBIDI 15515). Photographs by Germán Chávez (A–B, G–J, M–N) and Alessandro Catenazzi (C–F, K–L).

Fig. 7. Keeled dorsum in species of Potamites Doan & Castoe, 2005 showing the pattern of the dorsolateral keeled rows (blue) and paravertebral keeled rows (red). A. P. hydroimperator sp. nov. (CORBIDI 13915, holotype). B. P. ecpleopus Cope, 1875 (CORBIDI 11338). C. P. erythrocularis Chávez & Catenazzi, 2014 (CORBIDI 21841). D. P.juruazensis Avila-Pires & Vitt, 2001 (MPEG 17775, holotype). E. P. montanicola Chávez & Vasquez, 2012 (CORBIDI 8322, holotype). F. P. ocellatus Sinitsin, 1930 (AMNH 22512, holotype). G. P. trachodus Uzzell, 1966 (CORBIDI 15515).

Fig. 8. Lateral views comparing the condition of tubercles on flanks and sides of the neck (red arrows) and anterodorsal scales on limbs (green arrows). A. Potamites hydroimperator sp. nov. (paratype ♂, CORBIDI 14468). B. P. ecpleopus Cope, 1875 (uncollected ♂) from Yurimaguas. C. P. ecpleopus Cope, 1875, ♂ (CORBIDI 9516) from Cerros de Kampankis. Photographs by Germán Chávez (A), Angel Chujutalli (B) and Alessandro Catenazzi (C).

Fig. 1. Map showing the type locality of Potamites hydroimperator sp. nov. (red star), and the potential geographic distribution of P. ecpleopus Cope, 1875: Balsapuerto, Moyobamba, and Rioja, proposed by Uzzell (1966) adding Pongo de Caynarachi and Cerros de Kampankis as potential localities suggested herein.

Fig. 6. Panoramic view of the primary forest on the mountains of the type locality of Potamites hydroimperator sp. nov. in El Sira Communal Reserve.