A new record of the echiuran echiurus echiurus (pallas, 1767) from the East Coast of Southern Africa

The species Echiurus echiurus (Pallas, 1767) of the family Echiuridae, originally described from shallow waters of the Belgian coast, was later recorded from many other localities in the northern hemisphere, predominantly in cold waters and extending even into the Arctic. The discovery of this species from the warm, subtropical waters of the east coast of southern Africa is the first record of its occurrence in the southern hemisphere and marks a considerable extension of its geographic range. The species is briefly redescribed and some of the taxonomic characters have been reviewed

An ultrastructural study of spermatogenesis and the mature spermatozoon of the ascidian Pyura stolonifera

In Pyura stolonifera, there is an orderly arrangement of the male germ cells within the testicular follicles. Cells in early stages are located at the outer surface of the follicle while those in later stages of differentiation, including mature spermatozoa, lie nearer to the lumen. Developing spermatocytes are connected by cytoplasmic bridges which persist up to the late spermatid stage. The cytoplasmic bridge is reinforced on each side by an osmiophilic layer. Microtubules appear in the cytoplasm around the outside of the nuclear membrane in the mid-spermatid stage. The mature spermatozoon consists of an elongate, spindle-shaped head and a long tail. The head, which is about 9 µm in length, is slightly curved and tapers anteriorly. It comprises an elongate, eleclron-dense nucleus, a single large mitochondrion and a thin layer of cytoplasm. There is no middle piece. The mitochondrion is disposed lateral to the nucleus. Granules (presumably glycogen) occur in the cytoplasm between the nucleus and the mitochondrion. Neither an acrosome nor any other structure corresponding to it was observed in sections of the apical region. A ‘fuzzy’ material, however, surrounds the apex. The tail is about 40 µm in length and 0.2 µm in diameter. The axoneme has the 9 + 2 arrangement of microtubules

The proposed transfer of the echiuran Ochetostoma capense to the genus Listriolobus

The taxonomic position of the echurian Ochetostoma capense is reviewed based on examination of type material and on specimens from the type locality. On the basis of the disposition of the inner oblique muscle layer, the species is transferred to the genus Listriolobus and is re-described as L. capensis

A comparative study of the morphology of the chondrocranium of Dendroaspis angusticeps and D. polylepis polylepis

The essential features of the chondrocrania of both D. angusticeps and D. polylepis polylepis are very similar and conform closely to the platytrabic ophidian type. Specialized features such as a marked reduction of the solum nasi, as well as of the orbitotemporal region of the chondrocranium are noticeable. The basal plate and the occipital and auditory regions do not differ in important respects from those described in other snakes. Taxonomic justification for the separation of these elapids into two distinct species is adequately confirmed by structural differences between their chondrocrania

Ochetostoma (Echiura) from southern Africa with a description of a new species

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The jaw musculature of Dendroaspis angusticeps and Dendroaspis polylepis polylepis (Ophidia, Proteroglypha) with some remarks on the venom apparatus

The venom apparatus in both species of Dendroaspis shows great similarity to that described in other proteroglyphs. There is a posterior bulbous portion or main gland and an anterior narrower portion, the accessory gland, that surrounds the secretory duct. The gland is enclosed in a very tough connective tissue capsule. Fibres from the m. adductor externus superficialis insert on the connective tissue capsule on the dorsal aspect of the venom gland. They serve to compress the gland and expel the venom when the snake strikes. Ventrally, fibres of the m. pterygoideus are also inserted on the investing sheath. This muscle supports the gland ventrally and also appears to play some role in venom ejection. The arrangement of the jaw musculature is similar in both species of Dendroaspis. Since the m. adductor externus superficialis is closely associated with the venom gland it has become highly specialized and exhibits great variation among snakes. This muscle in Dendroaspis differs from that in other proteroglyphs in the extension of its origin in a ventral direction over the postorbital bone to the maxilla. As in other elapids, the m. levator anguli oris is absent in both species of Dendroaspis

Thalassema (Echiura) from southern Africa with the description of a new species

Four species of Thalassema are currently known from southern Africa of which T. jenniferae is here described as new to science. T. diaphanes and T. philostracum are redescribed and figured. The discovery of T. diaphanes from the Natal coast marks an extension of its geographic range. T. thalassemum is briefly diagnosed but material of this species was not available. The taxonomie positions of two specimens of Thalassema, examined from the University of Cape Town collection, remain to be resolved. Adequate descriptions of both these specimens were not possible as the internal organs were badly damaged. A key for the identification of all the species in the genus is provided and the distribution of the southern African forms is discussed

A key to the species of Anelassorhynchus (Echiura) with a description of a new species from the east coast of southern Africa

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