Cordylus phonolithos, Marques & Ceríaco & Stanley & Bandeira & Agarwal & Bauer, 2019

Marques, Mariana P., Ceríaco, Luis M. P., Stanley, Edward L., Bandeira, Suzana A., Agarwal, Ishan & Bauer, Aaron M., 2019, A new species of Girdled Lizard (Squamata: Cordylidae) from the Serra da Neve Inselberg, Namibe Province, southwestern Angola, Zootaxa 4668 (4), pp. 503-524 : 509-518

Cordylus phonolithos sp. nov.

( Tables 1–2 ; Fig. 4–8 )

lsid: urn:lsid:zoobank.org:act:813340B4-8299-4B1B-A786-5552BDC0C722

C. namakuiyus [part]: Stanley et al. (2016: 209)

Holotype. A subadult male ( CAS 263581 , field number AMB 10296; Figs. 4–5A ) collected within a crevice in a granite boulder in the vicinity of N’Dolondolo ( Figs. 2 , 9 ), Namibe Province, Angola [- 13.80678ºN, 13.13507ºE, 752 m elevation], collected by L. Ceríaco, S. Bandeira and I. Agarwal, on 21 November 2016.

Paratype. A juvenile specimen ( INBAC: AMB 10272 [same as field number]; Fig. 5B ), collected at the same locality as the holotype, under a small granite rock on a larger rock, by the same collectors, on 20 November 2016 .

Diagnosis. A medium sized Cordylus species, identified to genus by the following combination of characters: fully limbed, strongly depressed triangular head and body, osteoderms present, rhomboidal, imbricate and keeled dorsal scales present, occipitals non-spinose, and spinose caudal and limb scales enlarged ( Branch 1998; Broadley & Branch 2002; Stanley et al. 2011). Cordylus phonolithos sp. nov. differs from all other species in the genus except for C. vittifer (Reichenow, 1887) , C. machadoi and C. namakuiyus , by the presence (versus absence) of a transverse row of elongated dorsal scales immediately posterior to occipitals ( Fig. 6 ). It is distinguished from C. vittifer by possessing an incomplete row of pre-occipital scales between posterior parietal and occipital scales (versus complete), and by having infralabials that are moderately deeply ridged (versus usually smooth). It is distinguished from C. machadoi by having a large keyhole-shaped interparietal in contact with frontoparietals and separating the anterior parietals (versus small, diamond-shaped interparietal not in contact with frontoparietal and never completely separating the anterior parietals in C. machadoi , see Fig. 6 ); having the intrusion of a scale in broad contact with the interparietal and occipitals, thereby separating posterior parietals (versus absence of this scale and posterior parietals in full contact in C. machadoi , see Fig. 6 ); a higher number of supralabials (6 in C. phonolithos sp. nov. versus 5 in C. machadoi ); males with fewer caudal scales at the 15 th tail whorl (8 in C. phonolithos sp. nov. versus 10–11 in C. machadoi ); an orange-brown dorsal body coloration (versus darker brown to black in C. machadoi ), the absence of dark speckles on throat and ventral body surfaces (versus presence in C. machadoi ) and a reduced, widely separated posteromedial parietal process (similar to C. angolensis and unlike C. machadoi , in which it is extensive and forked, and C. namakuiyus , in which it is extended and unbifurcated). It is distinguished from C. namakuiyus by having the intrusion of a scale in broad contact with interparietal and occipitals, thereby separating posterior parietals (versus absence of this scale, posterior parietals in full contact, see Fig. 6 ); a higher number of supralabials (6 in C. phonolithos sp. nov. versus 4–5 in C. namakuiyus ); a higher number of femoral pores (7 in C. phonolithos sp. nov. versus 4-6 in C. namakuiyus ); a higher number of generation glands (16–17 in C. phonolithos sp. nov. versus 12 in C. namakuiyus ); males with fewer caudal scales at the 15 th tail whorl (8 in C. phonolithos sp. nov. versus 10 in C. namakuiyus ); absence of osteoderms on throat and ventral surfaces (versus presence), and significantly thicker caudal osteoderms than dorsal osteoderms (resembling C. machadoi and C. angolensis ); temporal scales are weakly keeled (versus strongly keeled). In coloration C. phonolithos sp. nov. is quite similar to C. namakuiyus , although the new species has a more vibrant coloration (orange-brown versus light brown). It is distinguished from C. angolensis by having a large keyhole-shaped interparietal in contact with frontoparietals, thereby separating anterior parietals, with an intrusion of a scale in broad contact with interparietal and occipitals (versus small, diamond-shaped interparietal not in contact with frontoparietal, thereby never completely separating anterior parietals, posterior parietals in broad contact, see Fig. 6 ); fewer ventral transverse scale rows (23 versus 27), orange-brown dorsal body coloration (versus brown with blackish speckles over paler dorsal ground coloration), and by the absence of a longitudinal series of whitish speckles along dorsal surface (versus presence of two longitudinal series of small whitish speckles along dorsum), and presence (versus absence) of a loreal.

Description of holotype. SVL 71.4 mm. Head and body depressed. Head 1.3 times longer (21.6 mm) than broad (16.5 mm). HH 8.7 mm. SEL 8.2 mm. Nasals in median broad contact; entire frontonasal lozenge-shaped, broader than long, separated from frontal by enlarged prefrontals (in median contact, forming a suture), separated from rostral by nasals, separated from loreal by prefrontals; frontal in contact with first and second supraoculars, followed by a pair of frontoparietals in broad, median contact; a distinctive keyhole-shaped interparietal in broad contact with the frontoparietals, separating anterior parietals; intrusion of a scale in broad contact with interparietal and occipitals, thereby separating posterior parietals; right posterior parietal scale is fragmented; parietal window visible; 10 rugose occipital scales; 10 elongated nuchal scales. Four supraoculars and three supraciliaries. Nasals large, with nostril pierced centrally on upper margin. Loreal in contact with preocular, nasal and first two supralabials; three suboculars, well separated from the lip by the third, fourth and fifth supralabials. Rostral twice as broad as deep; supralabials 6; infralabials 6; chin shields 5. Mental twice as broad as long; gulars smooth, enlarged and forming transverse rows posteriorly, with 17 gulars between the posterior extent of the jaws. Dorsal scales rectangular, rugose, strongly and obtusely keeled; dorsals and laterals in 25 transverse and 23 longitudinal rows; ventrals squarish, smooth, in 23 transverse and 17 longitudinal rows. Scales on dorsum of limbs large, strongly keeled and spinose with thin, non-imbricated osteoderms; subdigital lamellae under fourth toe 15; SAL 28.9 mm. AGD 32.4 mm. HML 9.3 mm, RUL 7.9 mm; FL 12.9 mm; TFL 10.6 mm; LTL 9.8 mm; femoral pores seven; generation glands 16–17. Tail with whorls of large, elongate, strongly keeled, spinose and acuminate scales, spines directed posteriorly; largest spines in dorsolateral position.

Cranial osteology. The parietal is pentagonal with two short, well-spaced posteromedial processes bracing a very small, laterally flattened posteriomedial supraoccipital process ( Fig. 7 ). The premaxilla is unpaired and bears seven pleurodont teeth and five foramina, with a dorsal process that extends posteriorly to be clasped by the nasals, which themselves insert into an unpaired frontal posteriorly and prefrontals posterolaterally. The maxilla is typically scinciform, with a deeply grooved crista dentalis and 20 pleurodont teeth. A laminar lacrimal lies medial to the facial process of the maxilla, extending from the posterioventral process of the prefrontal to the anterior process of the jugal. No palpebral is present, though the prefrontal has a small, flattened, laterally projecting tubercle that supports the anteriormost superorbital osteoderm in much the same way. The jugal is triangular in cross-section and asymmetrically T-shaped, with a tapering anterior process and a broad, truncated posterior process that extends along and past the posterior edge of the maxilla. Edentate pterygoids extend back to connect with the quadrates, becoming C-shaped in cross-section posterior to the epipterygoid condyle. The squamosal is curved and blade-like, circular in cross-section anteriorly, becoming flattened posteriorly, where it articulates with the cephalic condyle of the quadrate and the supratemporals. Supratemporals are flattened, sickle-shaped and unfused with the paroccipital processes. The bones of the braincase are unfused, suggesting that this individual may be a subadult. The prootic bears an extended alar process, a well-developed, anteriorly expanded crista prootica, and a very weak supratrigeminal process. Basipterygoid processes are well developed and flattened. The lower jaw has a large adductor fossa, a flattened and medially curved retroarticular process, a medially open Meckelian canal and a dentary with a strong subdental shelf, 22 mandibular teeth, and 11 dentary foramina.

Postcranial osteology. The holotype has 25 presacral, two sacral and 16 postsacral vertebrae ( Fig. 7 ). There are five cervical ribs, three sternal ribs and two xiphisternal ribs. The asternal ribs are asymmetric, with four long ribs with ossified costal cartilage and six short asternal ribs on the left side and five long and seven short ribs on the right. The first three cervical ribs are distally flattened with bifid cartilaginous projections. The pelvic girdle is well developed and flattened. No iliac tubercle is present. There is a well-developed, ventrally angled pubic tubercle directly anterior to the obturator foramen. Both hypoischium and hyperischium are well developed. Pubic bones are well separated by a bifurcate prepubic cartilage. The sternal plate is broad and lacks a fontanelle. Interclavicle cruciform, clavicles rod-like and flattened dorsally. The epicoracoid is narrow and curved, connecting the scapular ray to the primary and secondary coracoid rays, but not to the anterior process of the scapular. The condyles of long bones are unfused and the metatarsals and metacarpels are not fully developed, suggesting that this individual is not fully adult. Digits display the typical squamate phalangeal arrangement of 2-3-4-5-3 for the manus and 2-3-4-5-4 for the pes.

Osteoderms. Scales of the dorsal and temporal regions of the skull and the ventrolateral aspects of the jaws are underlain with rugose osteoderms ( Fig. 8 ). These osteoderms are fused to the proximal parietal, frontal and postorbital bones, although the mesokinetic and metakinetic joints appear unobstructed and flexible. The tail, legs and dorsal and lateral aspects of the body are covered in osteoderms ( Fig. 9 ). The dorsal and lateral trunk are protected by noncontiguous, rectangular, 100-200 µm thick osteoderms that become increasingly keeled and mucronate laterally. The caudal osteoderms are significantly thicker (up to 500µm), sharply spined and arranged in imbricate transverse whorls. The whole limbs are covered by imbricate circular/rhomboid osteoderms, keeled and mucronate dorsally, plate-like ventrally. The gular and ventral regions lack osteoderms.

Coloration. Dorsum orange-brown, fading to dirty yellow laterally. Head orange-brown; supralabials and infralabials yellowish; a dark-brown bar extends from the posterior aspect of the eye to the temporals. The base of the tail is brown, with an orange coloration similar to that the laterally that extends towards the tip; dorsum of limbs dark brown. Laterally, a dark-brown line extends from the neck towards the insertion of the forelimbs. The body venter is cream and subcaudal surface is faded orange.

Variation. Variation in meristic counts of the type series is reported in Table 2 . The single juvenile paratype agrees almost entirely with the holotype, although, the loreal and the preocular scales are fused and the right posterior parietal is entire. Measurements of the paratype are the following: SVL 49.9 mm; HL 15.2 mm; HW 10.7 mm; HH 6.4 mm; SEL 5.8 mm; SAL 20.2 mm; AGD 23.1 mm; HML 6 mm; RUL 5.4 mm; FL 7.9 mm; TFL 7.8 mm; LTL 8 mm.

Distribution. The new species is known only from N’Dolondolo, at the base of the Serra de Neve Inselberg in Namibe Province, Angola. The observational record cited by Stanley et al. (2016), originally identified as C. namakuyius from “Sera [sic] de Neve” (= Serra da Neve) is likely to correspond to C. phonolithos sp. nov.

Habitat and Natural history notes. This species was found in granite outcrops in “sparse Miombo” forest ( Fig. 10 ), dominated by trees of the genera Brachystegia and Jubernardia ( Grandvaux-Barbosa 1970). The juvenile paratype was found under a small granite rock on a larger rock, while the holotype was collected from within a crevice in a granite boulder. The latter was exposed outside of the crevice, quickly sheltering in response to our presence. CT scanning of the holotype revealed a myriapod carapace in its digestive tract.

Etymology. The specific epithet “ phonolithos ” is a noun in apposition from the Greek “ phono” = sound + “ lithos” = rock, which means “sound stone”. In the local Mucobal language the type locality name, “N’Dolondolo” means literally “rock that sounds like a bell” or “bell” and stems from the presence of a large and famous phonolite stone at the locality. Phonolites are rare igneous volcanic stones of intermediate composition between felsic and maphic, with aphanitic to porphyritic texture that produce a very distinctive metallic sound when hit, similar to the ringing of a metallic bell. We suggest “N’Dolondolo Girdled Lizard” and “Lagarto Espinhoso de N’Dolondolo” as the English and Portuguese common names, respectively, for this species.

Figures

FIGURE 2. Map showing localities for Cordylus species in Angola. Yellow circle—C. angolensis (type locality: Caconda); Red circle—C. phonolithos sp. nov, (type locality: Serra da Neve); Blue circles—C. machadoi (type locality: Serra da Leba); Pink circles—C. namakuiyus (type locality: Caraculo). Major cities are represented by an orange triangle. Principal plotted localities include both bibliographic (Marques et al. 2018) and museum records.

FIGURE 4. Dorsal and ventral whole-body views (left) and Dorsal, lateral, and ventral views of the head of the holotype of Cordylus phonolithos sp. nov. (CAS 263581).

FIGURE 5. Cordylus phonolithos sp. nov. in life (A. Holotype CAS 263581; B. Paratype INBAC:AMB 10272). N’Dolondolo, Serra da Neve, southwestern Angola (Photos by Luis Ceríaco).

FIGURE 6. Comparison of head scalation between C. machadoi, C. phonolithos sp. nov., C. namakuiyus and C. angolensis.

FIGURE 7. Figure showing Cranial and postcranial osteology of CAS 263581 Cordylus phonolithos sp. nov. holotype. An= angular, Art = articular, Bo = Basioccipital, Bpt= Basipterygoid, Co = coronoid, De = dentary, Ec = ectopterygoid, Ep = epipterygoid, F = frontal, Hi = hyperischium, Ho = hypoischium, J = jugal, Mx = maxilla, N = nasal, P = parietal, Pa = Palatine, Pf = postfrontal, Pmx= premaxilla, Po = Postorbital, Pocc = paraoccipital, Pp = prepubic cartilage, Ppmp = posteriomedial process of the parietal, Prf = prefrontal, Pro = prootic, Pt = pterygoid, Q = quadrate, Sq = squamosal, St = supratemporal, Vo = vomer.

FIGURE 8. Cranial morphology and osteodermal variation on the different Angolan Cordylus species, colorized to show crosssectional thickness.

FIGURE 9. Whole body osteodermal variation on the different Angolan Cordylus species, colorized to show cross-sectional thickness.

FIGURE 10. Habitat view of the type locality of Cordylus phonolithos sp. nov. (Photo by Ishan Agarwal).