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Tanta University (1989)

Ecological and Anatomical Studies on the Rodents of Genus Psammomys Found in Egypt

Salem, Mohamed Labeb.

Titre : Ecological and Anatomical Studies on the Rodents of Genus Psammomys Found in Egypt

Auteur : Salem, Mohamed Labeb.

Etablissement de soutenance : Tanta University

Grade : Master of Science (MSc) in Zoology 1989

Résumé
Ecological and anatomical studies were carried out on the common fat sand rat Psammomys obesus ( Cretzschmar , 1828 ) and it can be concluded that : - The fat sand rat is a robust jird distributed in the northwestern part of Nile Delta, northen part of Western Desert and Sinai in Egypt. - Genus Psammomys is represented by three subspecies ; Psarnmomys obesus obesus, Psarnmomys -o besus nicoli and Psammomys obesus terraesnctae. - The ears are relatively short and are broadly rounded. - Pellage is fine, soft and dense, attaining about 16 mm. in length mid dorsally. The dorsal colouration in general is yellowish diffusely and speckled with black. - The tail is shorter than the head and body length. It is fully haired with black terminal tuft. - The facial vibrissae are represented by four types ; buccal, interramal, superciliary and genal ones. - The limbs are robust and the feet are heavy, the digits are amed with claws. The soles are clad with rather long hairs on their distal parts, and there is a large naked dustay patch on the heel. - The palmer and planter surfaces of the digits are naked. The skin of the palmer surface contains two row of pads, a proximal row of two carpal pads and a distal row of three inter-digital pads. - The skin of the planter surface includes five pads, two proximal metatarsal pads and three distal inter-digital ones. - There are three pairs of teats-in the adult female specimens, one pectoral pair, and inguinal pairs. - The skull is robust with angular shape, and the rostrum is moderatly long and robust. - The posterior extrimities of the nasals do not reach the level of the fronto-maxillary sutures in the subspecies obesus, whereas this level reach in both P. o. nicolli -and -P.o. terraesnctae. - The interparietal is laterally compressed, its lateral diameter is slightly longer than its antero-posteriorly diameter. The supraorbital ridges are well developed with pronounced angular postorbital process. The incisive foramina are narrow with slite-like shape, the posterior palatine foramina are small. The mesopterygoi. d has au-shaped appearance with a deep pterygoid fossa. The tympanic bullae are large, the meati are swallen and bulbous. The suprametal triangle is large and bulbous : - The upper and lower pairs of the incisors are pigmented orange and ungrooved. Molariform teeth are of lophdont- bunodont type. The first upper molar with two large and one small root, the second molar with transient fold, the third molar is simple. - The mandible is robust with short condyler process. - There are seven cervical, twelve thoracic, seven lumber, four sacral-pseudosacral and twenty three caudal vertebrae. - The neural spine of axis of the cervical region is the heaviest and broadest of the whole vertebral column. The centrum of the sixth cervical has two large inferior lamellae. - The neural spine of the second thoracic vertebra is the longest of the whole vertebral column. The last two thoracics are devoid of transverse processes but with well developed metapophyses and anapophyses. - The last two lumber vertebrae are devoid of anapophyses. The first lumber vertebra has much reduced transverse processes. - The four sacral-pseudosacral vertebrae are partially fused without anapophyses. - In the caudal vertebrae, the neural spines, the transverse processes and metapophyses are well detected only in the first four caudals. - There are twelve pairs of thoracic ribs, the first seven pairs are true ribs. The sternum consists of manubrium, four separated stemebrae and a long, rode-like xiphisternum with the xiphoid cartilage.

Présentation étendue (EULC)

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