Acanthocercus gregorii ( Günther, 1894: 86 )

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 : 802-805

Acanthocercus gregorii ( Günther, 1894: 86)

( Figure 13 (a))

1894 Agama gregorii Günther, Report on the collection of reptiles and fishes made by Dr J. W. Gregory during his expedition to Mount Kenia [sic]. Proceedings of the Zoological Society, London 1894: 84–91.

1957 Agama atricollis loveridgei Klausewitz, Eidonomische Untersuchungen über die Rassenkreise Agama cyanogaster und Agama atricollis . 2. Die Unterarten von Agama atricollis . Senckenbergiana biologica 38: 157–174: 163. Holotype: SMF 10138, from ‘Kakoma, O-Afrika’ [= Tanzania], East Africa ( Figure 13 (b)).

Lectotype

BMNH 1946.8 .28.67, from ‘ Mkonumbi , a grassy coast district with salt-swamps’, Coast Province, Kenya, East Africa.

Description

The largest species (total length of adult males up to 360 mm [adult males SVL: 91–138 mm, x = 119.2 mm, n = 23], adult females to 300 mm) of the genus, but similar in body size to A. atricollis ; tail a third to a half longer than the SVL, but there is a series of specimens from one locality in the Serengeti that have extremely short tails, shorter than the SVL. Head distinctly broad in males, lacking the occipital scale. Ear opening as large as the eye, tympanum conspicuous. Nasal scale not convex, smooth and slightly below the canthus rostralis. Nuchal crest absent. Distinct from A. atricollis in possessing many enlarged, white coloured dorsal scales, forming a dotted pattern (= A. loveridgei morphotype) or forming a dotted pattern with up to five transverse scale rows (= A. gregorii morphotype). Body scalation heterogeneous, dorsal matrix scales small, smaller than ventral scales, irregularly intermixed by enlarged scales, sometimes forming distinct transverse scale rows. Enlarged scales keeled, most concentrated at the vertebrate. Vertebral zone covered by enlarged scales intermixed with smaller matrix scales, not separated by distinct rows of enlarged scales from the lateral parts of the body. Body scales are arranged in 88–126 (x = 103.8, n = 23) rows around midbody and 52–85 (x = 66.5, n = 23) longitudinal rows along the vertebrae. Ventral scales smooth, smaller than the enlarged dorsal scales, but larger than the matrix scales, in 77–92 (x = 83.3, n = 23) longitudinal rows. Gular scales small, smooth to feebly keeled, but erect and about the same size as the ventral scales. Males with one to three continuous rows (x = 2.0, n = 22) with a total number of 7–37 (x = 19.0, n = 22) precloacal pores, lacking in females. Dorsal scales of the basal part of the tail larger than those on the other parts of the tail, often forming a distinct patch of thick and swollen scales.

The coloration in life is poorly known. Günther (1894), in the first description, mentioned the throat and upper parts of the body bluish, but head, enlarged scales and basal portion of the tail yellow, while Sternfeld (1912) described the throat, chest and sometimes belly as reticulated blue and the dorsally enlarged body scales yellow. According to Klausewitz (1957) the throat of adult males is uniform greenish blue, head bluish green, body uniform blue and the tail bi-coloured yellowish at the base and brownish at the tip.

Distribution

Acanthocercus gregorii has the widest distribution within the A. atricollis -complex ( Figure 14 ). It is known from Ethiopia, Kenya, Tanzania, Rwanda, Burundi and extreme northern Mozambique. Klausewitz (1957) mentioned specimens from Uganda (as A. loveridgei ) but it was not possible to confirm this and the presence of A. gregorii in Uganda is dubious. He ( Klausewitz 1957) also recognized ‘ A. loveridgei ’ from Lake Bengweulu and the southern margins of the Luangwa Valley in Zambia. The previous 1 = Gojam; 2 = Batia; 3 = Lit Marafia; 4 = Didessa [Oromia]; 5 = Addis; 6 = Adda; 7 = Modjo; 8 = Adama [Nazareth]; 9 = Welenchiti; 10 = Akaki; 11 = Mount Zaguala; 12 = Maki River; 13 = Wonji; 14 = Harra, Lake Zuai; 15 = Lake Langano; 16 = Didessa; 17 = without locality; 18 = Lake Awasa; 19 = between Dodola and Adaba; 20 = Dodola; 21 = Mount Gaysay; 22 = Dinshu; 23 = Sheikh Husein; 24 = Sidam Bale bridge; 25 = Kebre Mengist; 26 = Felenguai; 27 = just N of Neghelli; 28 = Neghelli; 29 = Huri Hills; 30 = Moyala; 31 = Marsabit; 32 = Elgonyi; 33 = Maralal; 34 = Ntumot Lagga; 35 = Gorba Tula; 36 = Guaso Nyiro; 37 = Kericho Valley; 38 = Kirui; 39 = Lake Elmenteita; 40 = Naivasha; 41 = Fort Hall; 42 = Thika; 43 = Nairobi; 44 = Nairobi National Park; 45 = Attui; 46 = Narok; 47 = South N ’ guassa Mjiro River; 48 = Ngong Hills; 49 = SW of Ngong Hills; 50 = Kajiado; 51 = Sultan Hamud; 52 = Namanga; 53 = Makneni; 54 = Lamu island; 55 = Mkonumbi; 56 = Gede; 57 = Malindi district; 58 = Mount Sagalla; 59 = Mombasa; 60 = Mnambe Village; 61 = Tanga; 62 = Maweni; 63 = Korogwe; record is now referred to A. cyanocephalus and the latter to A. branchi . Therefore, ‘ A. loveridgei ’ (= A. gregorii ) does not occur in Zambia. Specimens of the A. gregorii morphotype are known from coastal East Africa between Lamu Island, Kenya in the north and Tanga, Tanzania in the south, as well as from two localities in the Serengeti National Park (see Figure 15 ). All other records refer to the A. loveridgei morphotype. Acanthocercus gregorii is sympatric with A. minutus in Ethiopia, with A. kiwuensis in Rwanda and Burundi, and with A. ugandaensis in Kenya and northern Tanzania. However, the detailed limits of its distribution are still incompletely known.

Habitat and ecology

Detailed information is sparse and inconsistent. Günther (1894) mentioned A. gregorii as ground living and described the habitat as ‘a grassy coast-district with salt-swamps’. In the Serengeti specimens were observed in rocky areas and on the ground hiding, even in skulls of large mammals, but also on acacia trees (PW, own observation). According to these observations, A. gregorii seems not to be a strictly tree-dwelling species, in contrast to e.g. A. atricollis . Sternfeld (1912) mentioned gravid females in December from Uvira Kasongo.

Figures

Figure 13. (a) Lectotype (BMNH 1946.8.28.67) of Acanthocercus gregorii, from Mkonumbi, Kenya. (b) Holotype (SMF 10138) of Acanthocercus atricollis loveridgei, from ‘Kakoma, O-Afrika’ [=Tanzania], East Africa.

Figure 14. Distribution of Acanthocercus gregorii and A. minutus. The numbers refer to the specific localities.

Figure 15. Holotype (ZMB 23906) of Acanthocercus kiwuensis, from Kissenji, Rwanda.