1994. Volume 1. No. 1. Contents

ON UNUSUAL PECULIARITIES OF HEAD MORPHOLOGY IN THEROCEPHALIAN Hexacynodon purlinensis

L. P. Tatarinov

A rudimentary chordal canal and pits for basicranial muscles with three pairs of openings for segmental ventral nerves were indicated on basioccipital of H. purlinensis. Up to now these nerves in land vertebrates were reported only for larvae of some amphibians. The groove on the occipital edge of squamosum, in which the external acoustic meatus is traditionally reconstructed, is connected with vascular openings on the distal part of mastoid process and with broad vascular canal trending between squamosum and quadratum. External to the medial sutural junction of basioccipital and basisphenoid the two bones are separated by fissure. Basisphenoid forms a short process here passing into the groove on the edge of basisphenoid. This articulation corresponds to the rudimentary intracranial joint in crossopterygians. In the bottom of basioccipital just anterior to the occipital condyle are deep cavities, connected by diminutive foramina in condyle with the vertebral canal. This cavity probably contained the posterior endolymphatic sac, and foramina conveyed endolymphatic ducts. The anterior endolymphatic sac was located possibly in the cavity anterior to fenestra ovalis, delimited by basioccipital, basisphenoid, and prootic. Due to the development of oblique crest on the quadrate condyle the opening of mouth was attended by lateral displacement of lower jaw. Such a displacement was possible only in condition if intramandibular mobility between dental (and splenial) and postdental block of mandibular bones.

Key words: morphology, skull, therocephalians, Hexacynodon.

TENDONS OF JAW MUSCLES IN AMPHIBIA AND REPTILIA: HOMOLOGY AND EVOLUTION

N. N. Iordansky

Patterns of the tendinous skeleton of jaw muscles in various groups of Amphibia and Reptilia are considered. In the jaw adductors of amphibians there are three basic systems of tendons: coronar, subarticular and pterygoidal (the latter only in the Gymnophiona). In reptiles the tendinous framework of jaw muscles is more developed. In the diapsid Reptilia the quadrate tendinous system appears, and the subarticular one is completed by retroarticular aponeurosis. Evolution and homology of tendinous structures are discussed in connection with these of the jaw adductor muscles. The anterio-medial sheet of coronar aponeurosis and the subarticular aponeurosis inhere in the internal jaw adductor, while oilier parts of coronar aponeurosis are usually connected with the external one. The M. pterygoideus anterior of the crocodilians inserts onto the anterio-medial sheet of the coronar aponeurosis and seems to be homologous with the M. pseudotemporalis of other reptiles. The general pattern of the jaw adductor tendons of the Ophidia may be derived from that of the Gekkota, while the pattern of the Amphisbaenia from that of the Autarchoglossa.

Key words: tendons, jaw muscles, homology, evolution, Amphibia, Reptilia.

POSTMATURATION SKULL DEVELOPMENT IN Xenopus laevis (ANURA, PIPIDAE): LATE-APPEARING BONES AND THEIR BEARING ON THE PIPID ANCESTRAL MORPHOLOGY

S. V. Smirnov

Cranial morphology was examined in 2-1/N12-year-old of Xenopus laevis. Cranial development was shown to continue after sexual maturation, and in older animals, elements that are commonly admitted as being absent in X. laevis (and in pipids) make their appearance. Among these are the palatine, the preorbital process of the maxillary, and the lateral alae of the parasphenoid. Vomers, which are usually azygous in Xenopus, become paired in old specimens. Two additional dermal ossifications previously recorded only in some casque-headed hylids (Trueb, 1970), were revealed in the skull of the 9- and 12-year-old X. laevis frogs. These bones, which lie on the premaxillary symphasis and dorsal to the septum nasi, are proposed to be homologous with the postrostrals of crossopterygians. Xenopus is proved to be a neotenic frog in which morphological underdevelopment results from the incomplete realization of its morphogenetic program caused by the retardation of somatic development. Prolongation of somatic development occurring in old animals permits the animal's morphogenetic program to be realized more completely, and features normally lacking in Xenopus but characteristic of its presumed ancestor may make their appearance.

Key words: pipids, neoteny, skull development

ON UNIQUE FORMS OF ANOMALOUS SACRAL STRUCTURE IN TAILLESS AMPHIBIANS

E. E. Kovalenko and S. E. Danilevskaya

The unique structural anomalies of spinal column caused by unilateral development of pelvis are described in an adult specimen of Xenopus laevis and 2 larvae of Rana temporaria. In all the specimens the unilateral development of sacrum was observed. The described anomalies support the hypothesis of deforming influence of developing ilium on posteromost presacral segments as well as some assumptions on the factors determining the morphogenetic process in anurans.

Key words: Amphibia, Anura, sacral structure, variations, unique forms.

Vietnascincus rugosus, A NEW GENUS AND SPECIES OF THE Dasia-LIKE ARBOREAL SKINKS (SAURIA, SCINCIDAE) FROM VIETNAM

I. S. Darevsky and N. L. Orlov

A new genus and species of arboreal lygosomine skinks from Gilai-Contum province in Central Vietnam are described. This new alpha-palatal skink is characterized by having rugose upper head shields, sharply keeled dorsal scales, longitudinally striped body pattern and some other characters different from those typical for members of the genera Dasia, Lamprolepis, and Apterygodon. Phylogenetic relations of new skink are discussed.

Key words: Reptilia, lizards, Scincidae, Vietnascincus, Vietnam, taxonomy.

SOME ASPECTS OF HISTORICAL BIOGEOGRAPHY OF ASIAN ROCK AGAMIDS

N. B. Ananjeva and B. S. Tuniev

The genesis of areals of Asian rock agamids belonging to the genus Laudakia Gray, 1845 is considered. The hypothesis about two routes of radiation of these lizards endemic for arid mountain regions of Palearctic is offered. The southern route from the hypothetical center of origin in the area of mountain systems of Hindukush and Himalayas passed in the conditions of southern subtropics with well developed belt of sclerophilous forests. This evolutional line with "caucasia" complex remains the relic areas in forest regions. Northern group of species with "himalayana" complex had its speciation in northern subtropic area with more severe climatic situation determined by strong continental and arid conditions. Altitudinal and biotopic differences of Laudakia species under their sympatric distribution are specially discussed.

Key words: Reptilia, Sauria, Agamidae, Laudakia, Palearctic Asia, systematics, biogeography, distribution, evolution.

ROLE OF PHYLOGENETIC RELATIONS AND CONDITIONS OF HABITAT OF LIZARDS OF "Lacerta saxicola" COMPLEX IN FORMATION OF THE HEAT RESISTANCE LEVEL OF TISSUE AS SPECIFIC CHARACTER

V. B. Andronikov, F. D. Danielyan, and R. A. Passinkova

The extent of resistance of animal cells and tissues to injurious heat effect is a cytophysiological criterion of species. In poikilotherms it can be determined both by phylogenetic relations and ecological conditions of a species' formation and existence. To analyze the relative role of these factors in formation of the tissue heat resistance level as characteristic of a species, a study was made on 9 species of lizards of the "Lacerta saxicola" complex. A characteristic feature of the complex is that some of the species belonging it are of hybrid origin, which implies that genetically they are closely related to other, parental forms. Heat resistance level of muscle tissue in a hybrid species may differ from the parental forms if the conditions of its existence are different. On other hand, genetically unrelated species living under similar conditions may have the same level of heat resistance of muscle tissue. Interspecific differences in heat resistance of muscles cannot be explained by phylogenetic relations only. Of major importance in formation of the cellular heat resistance level in the process of speciation are ecological, and primarily, thermal conditions of the environment.

Key words: temperature adaptation, thermostability of cells and tissues, species-specificity, speciation, environment, reptiles, amphibians.

ANNOTATED CHECKLIST OF AMPHIBIAN TYPE SPECIMENS COLLECTION OF THE ZOOLOGICAL MUSEUM OF M. V. LOMONOSOV MOSCOW STATE UNIVERSITY

E. A. Dunaev and V. F. Orlova

The amphibian type collection of the Zoological Museum of M. V Lomonosov Moscow State University includes 38 specimens of 9 taxa. The following information is provided for each taxon: name, citation of original description, present status, characteristics of type materials (amount, sex, and age of specimens), type locality, collector, and date of reception. A short account of topotypes in the collection (39 specimens of 10 taxa) is also presented.

Key words: type specimens, zoological collections, nomenclature, Anura.

ECOLOGY OF THE HIMALAYAN NEWT (Tylototriton verrucosus) IN DARJEELING HIMALAYAS, INDIA

 S. L. Kuzmin, R. Dasgupta, and É. M. Smirina

In Darjeeling district, West Bengal, India, Tylototriton verrucosus was found in 10 localities. It lives in rice fields, tea gardens, meadows underlying the shores of pools, at the edge of woods. Reproduction in March - May (sometimes up to September). Female parental care and tendency to terrestrial breeding were observed. Metamorphosis is commonly in August - October, but sometimes the larvae overwinter. This might be the result of a prolonged reproductive period. The age of animals was determined by counting annual layers in phalange transverse sections. The age of sexual maturation is supposed to be 3 - 5 (mostly 4) years. Maximum age estimated 11 years old. The duration of hibernation is 4 - 5 months. The larvae prey mainly upon small crustaceans and aquatic insects, aquatic adults prey on insects, earthworms, amphibian ova and larvae. Data on natural enemies and parasites are presented. Conservation problems are discussed.

Key words: Amphibia, Caudata, Tylototriton verrucosus, distribution, reproduction, age determination, conservation.

A COMPARATIVE STUDY OF INTRA- AND INTER-POPULATION VARIATION IN TWO SYMPATRIC LIZARDS, Lacerta agilis boemica AND L. strigata IN DAGHESTAN

E. S. Roytberg

Using methods of statistical analysis, the extent of morphological inter- and intra-population variation in two sympatric lizard species (Lacerta agilis boemica and L. strigata) from the North Caucasus (Daghestan) was compared. 1042 specimens from 7 localities of lowland and foothill Daghestan were scored for 8 pholidotic features and 22 characters of head scutellation. The occurrence of evident differences in the extent of the interpopulation variation was revealed: the latter is higher in L. agilis as compared with L. strigata from the same localities. Two factors are proposed to be responsible for this difference: a) gene flow among populations which seems to be more intense in L. strigata and b) developmental homeostasis which seems to be higher in L. strigata if compared with L. agilis.

Key words: lacertids, pholidosis, head scutellation, variability.

CAPTIVE BREEDING AND CONSERVATION

COURTSHIP BEHAVIOR, FERTILIZATION OF EGGS, AND REARING IN CAPTIVITY OF THE SEMIRECHENSK SALAMANDER Ranodon sibiricus KESSLER (AMPHIBIA, CAUDATA)

R. Thorn

Courtship behavior of Semirechensk salamander, Ranodon sibiricus, in captivity was observed. Fertilization of eggs of this species of amphibian is of a typical hynobiid nature. Some details of courtship behavior in Ranodon sibiricus and Hynobius retardatus are compared and discussed.

Key words: Amphibia, Caudata, courtship behavior, captive breeding.