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Acanthocercus cyanocephalus (FALK, 1925)

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Higher TaxaAgamidae (Agaminae), Sauria, Iguania, Squamata (lizards)
Common NamesE: Falk’s Blue-headed tree agama
G: Falks Blaukehlagame 
SynonymAgama cyanocephala FALK 1925: 83
Stellio angolensis BOCAGE 1866 (nom. nud. fide WAGNER et al. 2018)
Acanthocercus cyanocephalus — CONRADIE et al. 2016
Acanthocercus cyanocephalus — MARQUES et al. 2018
Acanthocercus cyanocephalus — WAGNER et al. 2018: 797 
DistributionAngola, N Namibia, NW Zambia, SE Democratic Republic of the Congo (Zaire)

Neotype locality: “garden in Ikelenge (-11.241592, 24.273256), northern Mwinilunga District” (Zambia). Original type locality: “Angola” without further precision.  
TypesNeotype: ZFMK 88492 (collector P. Wagner) designated by Wagner et al. (2018: 27). Note that Falk 1925 did not designate a holotype. 
DiagnosisDiagnosis: 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 (Wagner et al. 2018: 799).

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 (Wagner et al. 2018: 799).

Note: The original description by Falk 1925 did not provide a diagnosis. 
CommentDescription: the original description by Falk is quite cursory, without a proper diagnosis: “Das ganze Tier von Kopf bis Schwanz ist ungefähr 35 cm lang. Der große, dreieckige , mit mächtigen Kaumuskeln versehen Kopf mißt ungefähr 7 cm, der starke, mit Biertelschuppen [maybe typo for “Wirtel-”] bedeckte Leib ist gut 15 cm lang. Die Oberseite des sich stets nur an und auf Bäumen aufhaltenden Tieres ist ein Baumstammgrün, nur der Kopf ist in ein wunderbares, leuchtendes Blau getaucht, so daß ich, falls diese Agame noch nicht benannt ist, den Namen: “Agama cyanocephalal” vorschlagen möchte.”

Distribution: Acanthocercus atricollis is not in Angola but Acanthocercus cyanocephalus is, fide Marques et al. 2018. See map in Wagner et al. 2018: 794 (Fig. 10) and Wagner et al. 2021: 459 (Fig. 8).

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 parti- cularly 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 (Wagner et al. 2018: 801).

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, caterpil- lars, ants, termites, Diptera, Hymenoptera, Orthoptera and Coleoptera (Wagner et al. 2018: 801). 
  • Conradie W and Branch WR. 2016. The herpetofauna of the Cubango, Cuito, and lower Cuando river catchments of south-eastern Angola. Amphibian & Reptile Conservation 10 (2) [Special Section]: 6–36 - get paper here
  • Falk, K. 1925. Herpetologische Berichte aus Angola (Portugiesisch West-Afrika) [Herpetological reports from Angola (Portuguese West-Africa)] Blätter für Aquarien- und Terrarienkunde Stuttgart 36: 81
  • Marques, Mariana P.; Luis M. P. Ceríaco , David C. Blackburn , and Aaron M. Bauer 2018. Diversity and Distribution of the Amphibians and Terrestrial Reptiles of Angola -- Atlas of Historical and Bibliographic Records (1840–2017). Proc. Cal. Acad. Sci. (Ser. 4) 65: 1-501 (Supplement II)
  • MARQUES, M. P., PARRINHA, D., SANTOS, B. S., BANDEIRA, S., BUTLER, B. O., SOUSA, A. C. A., ... & WAGNER, P. 2022. All in all it’s just another branch in the tree: A new species of Acanthocercus Fitzinger, 1843 (Squamata: Agamidae), from Angola. Zootaxa 5099 (2), 221-243 - get paper here
  • WAGNER, P., BUTLER, B.O., CERÍACO, L.M. & A.M. BAUER 2021. A new species of the Acanthocercus atricollis (SMITH,1849) complex (Squamata, Agamidae). Salamandra 57: 449–463 - get paper here
  • Wagner, Philipp; Eli Greenbaum, Aaron M Bauer, Chifundera Kusamba & Adam D Leaché 2018. Lifting the blue-headed veil – integrative taxonomy of the Acanthocercus atricollis species complex (Squamata: Agamidae). African Journal of Herpetology - get paper here
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