Acanthocercus cyanocephalus ( Falk, 1925 )

Wagner, Philipp, Greenbaum, Eli, Bauer, Aaron M., Kusamba, Chifundera & Leaché, Adam D., 2018, Lifting the blue-headed veil - integrative taxonomy of the Acanthocercus atricollis species complex (Squamata: Agamidae), Journal of Natural History 52 (13 - 16), pp. 771-817 : 797-802

Acanthocercus cyanocephalus ( Falk, 1925)

( Figure 12 )

1925 Agama cyanocephala Falk, Blätter für Aquarien und Terrarien-Kunde, Stuttgart 36: 83. Type locality as published:‘Angola’.

1866 Stellio angolensis Barboza du Bocage (nomen nudum), Jornal de sciencias mathematicas, physicas, e naturaes, Lisboa 1: 43. Type locality as published:

‘ Duque de Bragança’ [= Huila Plateau, fide Loveridge 1957], Malanje Province, Angola .

Neotype

ZFMK 88492 , adult male, collected in a garden in Ikelenge (−11.241592, 24.273256), northern Mwinilunga District , North-Western Province, Zambia, by Philipp Wagner.

Taxonomic comments

Falk (1925) described a rare agamid lizard, about 35 cm in total length (head length of 7 cm; body length of 15 cm), with a large, broad, triangular head, a brownish body and a blue head, which lived on trees in Angola. Additionally he mentioned that if this lizard is unknown, he would suggest the name ‘ Agama cyanocephala ’. Currently, only three large agamid lizards are known from Angola. Agama mucosoensis Hellmich, 1957 may be excluded based on the brief description in body and head coloration (see also Wagner et al. 2012a) and Falk (1925) was able to differentiate between Agama planiceps schacki Mertens, 1936 (mentioned as Agama planiceps Peters, 1862 by Falk) and the specimen described by him. Indeed, the few characters mentioned correspond well to a species of the Acanthocercus atricollis group, but the description is not adequate to identify the species itself and the type specimen was not deposited in a scientific collection. Based on the International Code of Zoological Nomenclature (ICZN 1999), this name has to be recognized. According to Article 12.1 every new name published before 1931 must satisfy the provisions of Article 11 and must be accompanied by a description of the taxon. The short description itself is in accordance to Article 11 and, moreover, Art. 11.5.1. explicitly mentions that a name proposed conditionally for a taxon before 1961 is not to be excluded on that account alone. Following Article 15.1 the conditional proposal is valid and the suggested name Agama cyanocephala Falk, 1925 is available. This study has shown that populations from Angola, Zambia and the southern DRC are clearly distinct from all other taxa of the atricollis complex, and consequently Falk’ s name should be regarded as valid rather than as a synonym. The designation of a neotype herein is in accordance to Article 75 of the code. Kurt Falk (1925), who settled in Angola as a German anthropologist, obviously gave a conditional description as his entire article is a published summary of a letter he sent to Germany and together with his description of the specimen he mentioned that ‘if it is a new species he would support the name (...) [translated from German]’. Accordingly, the male specimen he used for measurements and the brief description of the coloration was released or fed to his snakes, rather than preserved. To clarify the taxonomic status of the entire species group, we herein define a neotype for Agama cyanocephala Falk, 1925 and include a redescription of the taxon. A clear type locality is not given in the description. Kurt Falk studied different tribes in Angola and travelled extensively within the country. Therefore, the type locality can be restricted by original designation to Angola only. We chose a specimen from western Zambia (Ikelenge), close to the border to Angola as a neotype, as it is identical with the few characters given by Falk (1925) and, in contrast to available material from Angola, it still retains colour pattern and is available for molecular analysis.

In his checklist of specimens from western Africa, present in the Lisbon collection, Bocage (1866) mentioned the name ‘ St. angolensis ’. He thought that these specimens from Angola represented a new species which he meant to name ‘ St. angolensis ’, but Günther (curator at the British Museum at this time), after an examination of the specimens, suggested them as conspecific with Smith’ s ‘ nigricollis ’ (= Acanthocercus a. atricollis , see comment there) and for that reason, Bocage (1866) mentioned that and abstained from providing a description. Therefore, we recognize ‘ Stellio angolensis ’ as a nomen nudum.

Diagnosis

Acanthocercus cyanocephalus is characterized by its large size and the relatively short tail. There are relatively few enlarged, keeled, spinose scales on a matrix of small smooth scales, vertebral region with only very slightly enlarged scales, only half of the size or smaller than the enlarged keeled, spinose scales.

It is a large member of the genus with a total length up to 350 mm (SVL: 113–147 mm, x = 136.8 mm, n = 8), tail short, about 1.3 times longer than the SVL. Head distinctly broad in males like in other species of the genus. Ear openings about the same size or slightly smaller than the eyes, with the tympanum visible. Occipital scale lacking. Nostril slightly below the canthus rostralis. No vertebral crest. Scales arranged in 100–119 (x = 109.8, n = 8) rows around midbody and 58–78 (x = 71.4, n = 8) longitudinal rows along the vertebrate. Matrix scales small, usually smooth and scattered with enlarged keeled scales. Enlarged scales usually not organized in rows or clusters. Vertebral scales keeled, with a higher density of enlarged scales as on the flanks. Gular scales flat, smooth, juxtaposed and becoming smaller towards the gular fold. Ventral scales small and smooth, in 74–94 (x = 83, n = 8) longitudinal rows. Males with usually two continuous rows of 24–26 precloacal pores, which are lacking in females.

Differential diagnosis

Acanthocercus cyanocephalus is clearly distinct from all other species in the coloration of adult males: head und throat uniform blue, body black with numbers of whitish coloured scales forming a spotted pattern, first half of tail brownish, second half banded black and blue.

From some of the other species this taxon differs as follows: from (a) A. a. ugandaensis it differs in possessing a vertebral region without rows of enlarged, keeled scales or small scales which are framed by a row of enlarged scales, by its larger size (113–148 mm vs. 96–125 mm in adult males) and a shorter tail; from (b) A. a. kiwuensis it differs by its larger size, the shorter tail and it does not possess transverse rows of enlarged scales; from (c) A. a. minutus it differs by its larger size and a strikingly different coloration.

Acanthocercus cyanocephalus is similar in size and some aspects of pholidosis to A. atricollis and A. gregorii . However, it is clearly distinct from (a) A. gregorii by its slightly smaller size, a shorter tail, having smooth versus keeled gular scales, in not possessing longitudinal rows of enlarged pale dorsal scales, in possessing many fewer enlarged body scales and the enlarged scales are smaller, the vertebral region of A. gregorii is covered with enlarged, keeled scales only, whereas in the vertebral region of A. cyanocephalus small scales are scattered among enlarged ones, and the pelvic and femoral regions of A. gregorii are dominated by enlarged scales whereas in A. cyanocephalus there is a mixture of one half each of both scale types; and finally from (b) A. atricollis in possessing a significantly lower number of enlarged body scales, especially on the lateral parts of the body and in A. atricollis the vertebral region has a broad band of enlarged scales whereas in A. cyanocephalus there is a mixture of small and enlarged scales.

Description of the neotype

Adult male; habitus stout, with a large triangular head distinct from the body; tail short. Measurements. SVL 143.2 mm, tail length (TL) 187.0 mm, head length (HL) 42.3 mm, head with (HW) 39.8 mm, head height (HH) 21.8 mm, left forelimb 58.5 mm, left hind limb 84.8 mm. Pholidosis. Large teardrop-shaped nasal scale slightly below the canthus rostralis, directed laterally, pierced by the round nostril in its posterior part. Scales of anterior, lateral and central part of the head large, from the level of the ear scales are abruptly smaller, only about one fourth the size of the large head scales; head scales unequal in size, not directed, usually smooth, sporadically heavy keeled, free anterior margins of head scales only sporadically with sensory pits. 15 supralabial scales, 15 infralabial scales on both sides; supraocular scales smooth, 9 on each side; no parietal shield and pineal organ visible. Ear opening large, about the same size as the eye, margin bordered by a semicircle of ten spinose mucronate scales, tympanum superficial. No nuchal crest. Gular scales flat, smooth, juxtaposed and becoming smaller towards the gular fold. Dorsal body scales a mixture of small, usually smooth but sometimes keeled scales, some giving the impression of granular scales; and scattered enlarged keeled and sometimes mucronate or spinose scales, enlarged scales not organized in rows or clusters. Seventy-five dorsal scales in the vertebral region from midpoint of pectoral region to midpoint of pelvic region, consisting of a mixture of small and enlarged scales, not distinct from the rest of the body but all scales in the vertebral region are keeled. Ventral body scales smooth, slightly imbricate at their posterior margins, in 83 scales from midpoint of pectoral region to precloacal pores. Around midbody there are 125 rows of scales. Precloacal scales in two rows, 13 pores in the anterior, 11 in the posterior row. Scales on the dorsum of the forelimb unequal in size and strongly keeled, smooth on the underside, on the upper arm scales somewhat larger than the largest dorsal body scales, becoming smaller ventrally and distally. Scales on the dorsum of the hind limb keeled to smooth becoming completely smooth ventrally, on the upper thighs unequal in size and a mixture of small and scattered enlarged scales, enlarged scales as large as the enlarged dorsal body scales. In both, manus and pes, 4th digit is the longest, digital length decreasing 3-2-5-1, subdigital lamellae keeled and mucronate, 21 under left 4th digit. Tail arranged in whorls of four scale rings at the basal part of the tail, whorls becoming indistinct towards the tail tip, tail scales keeled and mucronate. First third of the tail extremely swollen, heavily built and laterally compressed, scales extremely large and thick, feebly to heavily keeled, much larger than the head or enlarged body scales. In the second third the tail is much thinner and slightly depressed. Coloration (after two years of preservation in ethanol): Head and neck blue. Ground colour of body and limbs black, sometimes with a bluish tint but dominated by a pattern of short whitish stripes and dots. Tail greyish at the base, followed by blue and brownish bands. Throat uniform bright blue, belly white mottled with black dots, underside of the tail dirty white.

Coloration in life

Males. Head, neck and parts of the shoulders brilliant blue. Body and limbs black, with a pattern of white stripes and dots. Tail at the base yellowish, followed by blue and brownish bands. Throat uniform bright blue, framed by yellowish dots on a blue background. Females. Female coloration is unknown but presumably similar to the other subspecies. Juveniles. Only known from juvenile males, which are uniform brownish with a pattern of pale brown and black stripes and dots and a banded tail. The black bar on the shoulders, typical for A. atricollis , is more distinct in juveniles than in adult males. The throat is white with a reticulated pattern of blue stripes. Belly and underside of the tail creamy white, belly marbled with a greyish pattern.

Variation

All examined specimens are similar in aspects of scalation and body proportions. One adult male (ZFMK 88491) shows three dark transverse bands between the limbs. The typical broad heads of adult males are absent in juvenile and subadult males.

Habitat

Specimens were collected on trees in Miombo woodland, gardens and plantations. One specimen was hiding in a termite mound, directly beside a large tree. In northern Namibia (Ovamboland) specimens were abundant and conspicuous on trees and particularly on isolated trees surrounding water bodies (pers. obs. A. Bauer.) In Manono ( DRC) the individuals were collected on man-made walls from small rocks and on buildings in the town in human disturbed areas, but not on trees.

Diet

A stomach content analysis of vouchers ( PEM 6360–6373 ) from the type locality and Sanolumba Village (southern DRC) found several types of arthropods: spiders, caterpillars, ants, termites, Diptera , Hymenoptera , Orthoptera and Coleoptera .

Distribution

Acanthocercus cyanocephalus is currently known from far northern Namibia, Angola, north-western Zambia, southern and south-eastern DRC ( Figure 10 ). Especially around the type locality it is known from several localities not noted on Figure 10 , because they are too close to each other to show on a continental scale: Hillwood Farm ( NMZB 10521 , 10574 ; ZFMK 88491 ); Hillwood Farm : Nature Reserve ( ZFMK 88493 ); Ikelenge ( NMZB 1606 ; ZFMK 88495–97 ); Isombo Stream ( NMZB 10659 ); Sakeji School ( NMZB 10485 , 10613 ; ZFMK 88494 ); Zambezi Bridge, NW of Ikelenge ( NMZB 7081 ) and from Sanolumba Village opposite the border within southern DRC ( PEM 6367–68 , 6371 ) .

Mythology

The Lunda people of north-western Zambia consider the blue-headed agama as poisonous and do not hunt or eat them (pers. observ. P. Wagner). They are relatively frightened to touch these lizards and the lizards are usually killed by children only.

Figures

Figure 10. Distribution of Acanthocercus atricollis, A. branchi and A. cyanocephalus. The numbers refer to the specific localities.

Figure 12. Neotype (ZFMK 88492, designated herein) of Agama cyanocephala, from Ikelenge, Zambia.