Larval development of Spondyliosoma emarginatimi (Cuvier & Valenciennes) (Pisces: Sparidae) from southern Africa

The larval development of the southern African endemic sparid Spondyliosoma emarginatum is described and illustrated from specimens collected in Algoa Bay and the Swartkops, Sundays and Swartvlei estuaries of the Cape Province. S. emarginatum has demersal eggs. Preflexion larvae are moderately elongate (BD = 18–23% BL) with body depth increasing to 31 % BL in postflexion stages. The head is rounded and the snout blunt but becomes more elongate in postflexion stages. There are short spines on the preoperculum. Flexion occurs at about 6 mm BL and postflexion larvae are characterized by distinct medio-lateral pigmentation. Osteological development is described from a series of cleared and stained specimens. All fins have the adult complement of spines and rays by 12 mm BL. The larvae of S. emarginatum are compared with those of the European S. canthurus and other southern African sparids.     

The ecology of Sphyraena barracuda (Osteichthyes: Perciformes) in the Kosi system with notes on the Sphyraenidae of other Natal estuaries

The ecology of Sphyraena barracuda was studied in the Kosi estuary system of Natal. Fry enter from the sea at a length of 20 mm and live in shallow marginal weed-beds until a length of 80 mm when they move to fringing Phragmites reed-beds. After reaching 300 mm they move to open water areas. No specimens longer than 500 mm were recorded and none were mature. Growth is rapid, they attain 180 mm in the first six months and after two years measure 400-500 mm. They leave the estuary after about two years. Their significance in the estuarine fish community is due to their predation, at all sizes, on a variety of estuarine-dependent juvenile fishes (e.g. Rhabdosargus spp., Mugilidae) and adults of estuarine species (e.g. Ambassis spp.). S. barracuda was recorded at salinities between 4°/oo and 35°/oo, only in very clear water and at temperatures from 14,4 °C to 37 °C. Sphyraena bleekeri and S. qenie, which are also clear-water species, were found at Kosi in salinities from 0,5 to 35%o. They are also piscivorous on a range of small teleosts. Sphyraena iello is the most widespread barracuda in Natal estuaries, but only juveniles were recorded. This species is tolerant of a wide range of turbidities and salinities which enables it to live under most estuarine conditions. The distribution, ecology and interspecific interactions among Sphyraenidae in Natal estuaries are discussed in relation to their feeding biology, habitat preferenda and physical tolerances.     

Reproductive cycle of the Namib giant ground gecko,Chondrodactylus angulifer (Squamata: Gekkonidae)

The reproductive cycle of the Namib giant ground gecko, Chondrodactylus angulifer, from southern Africa was described from a histological examination of gonadal material from museum specimens. Males followed a seasonal testicular cycle in which (based on available specimens) the major period of spermiogenesis occurred between September and December. The onset of spermiogenesis is not known as specimens from May to August were not available. Testes in regression were found in January, February and March. Testes in recrudescence were found in January, February, March and April. Females with enlarged ovarian follicles (>5mm length) were found in January/February and September to December. Mean clutch size for 36 females was 1.7 ± 0.47 S.D., range: 1–2. Evidence is presented that more than one clutch may be produced in the same reproductive season.     

First record of the echiuran Anelassorhynchus porcellus Fisher, 1948 from the east coast of southern Africa (Echiura: Echiuridae)

The Pacific echiuran species Anelassorhynchus porcellus (Fisher, 1948) was collected from the intertidal rocky shores at Perriers Rock and Isipingo Beach on the KwaZulu-Natal coast. This is the first known record of this species from South African waters. Anelassorhynchus porcellus, originally described by Fisher (1948) from several specimens collected in tidal pools south of Honolulu Harbour, Hawaii was later recorded and described by Edmonds (1960) from specimens collected from Heron Island, Queensland. The discovery of this species from the east coast of southern Africa considerably extends its geographical range. After closer examination of additional specimens of Anelassorhynchus gangae Biseswar, 1984 collected from the Kwazulu-Natal coast it is proposed that this species be recognized as a junior synonym of A. porcellus. Anelassorhynchus porcellus is redescribed and some of the taxonomic characters are reviewed.     

Mouthpart structure and function and the feeding mechanisms of Gerres (Teleostei)

Members of the genus Gerres feed almost exclusively on benthic invertebrates and have evolved efficient protrusible jaw mechanisms and modes of feeding. The methods employed in prey capture and feeding by five species that occur in the estuaries of Natal were studied using slow-motion cine photography and results were supplemented by field observations. All species use visual cues to detect and capture prey on or just below the surface of the substrate.

The protrusible jaw mechanism is the most important feature in prey capture. Bones and muscles involved in jaw movement were studied by dissecting preserved specimens and cleaning jaws and skulls of muscle. The whole mechanism of protrusion of the mouthparts was found to be controlled by two sets of muscles acting on a modified maxilla which together with the cross-palatine ligament forms a groove along which the ascending process of the maxilla can slide when the mouthparts are protruded. The setting up of a suction pressure within the mouth further aids the uptake of items from the substrate. However, whether or not suction pressure is applied depends on the prey type.     

A New Freshwater Goby (Teleostei: Gobiidae) from the Pongolo Floodplain,Zululand, South Africa

A new freshwater goby, Mugilogobius pongolensis sp. n. is described and figured as a species new to southern and eastern Africa. This record extends the zoogeographcal distribution of Mugilogobius Smitt, 1899, from the Indonesian archipelago and South Australia to the Indian Ocean and the eastern coast of Africa.     

Description and ecology of larvae of Glossogobius callidus and Redigobius dewaali (Gobiidae) from temperate South African estuaries

This paper describes the morphology and ecology of the larvae and early juveniles of two common gobiids in warm temperate South African estuaries. The early developmental stages of Glossogobius callidus and Redigobius dewaali were collected during plankton surveys in seven permanently open and five intermittently open estuaries along southeastern South Africa. Larval G. callidus have a characteristic ventral row of pigment that extends from the cleithral symphysis along the ventral midline of the tail to the end of the caudal peduncle; notochord flexion takes place at the yolk-sac stage, between 3 and 4 mm BL. Larval R. dewaali are characterized by having two very large stellate melanophores on the ventral surface of the trunk and tail, and internal pigment between the snout and hindgut; notochord flexion takes place between 4 and 6 mm. Body lengths at settlement for G. callidus and R. dewaali are 13 mm and 16 mm, respectively. G. callidus and R. dewaali dominate the larval gobiid catch in warm temperate estuaries. Estuary type and freshwater input played a defining role in the occurrence of larvae of these, often sympatric, species in temperate estuaries. Larval G. callidus occurred in both permanently open and intermittently open estuaries, and were most abundant in mesohaline regions over the spring/summer period. By contrast, larval R. dewaali occurred exclusively in permanently open estuaries and were more prevalent in the fresh and oligohaline regions in autumn. Larvae of both species were more prevalent in freshwater-rich estuaries. Densities of G. callidus and R. dewaali peaked at 101 and 3829 larvae per 100 m³respectively. The usefulness of using the early stages of these gobiids as indicators of estuarine health based on their specific and often prolific estuarine occurrence is discussed.     

Some aspects of the anatomy of Ochetostoma caudex (Echiura) from the east coast of southern Africa with Remarks on its taxonomic status

The degree of variation within the species Ochetostoma caudex was determined from 32 specimens collected from the east coast of southern Africa. The shape and distribution of the dermal papillae were uniform in all the specimens. The number of longitudinal muscle bands ranged from 14 to 21 with 16 to 19 being the most common. In most specimens the anal vesicles were almost equal to or slightly longer than the trunk and were covered with numerous, unstalked ciliated funnels. A comparison of O. caudex with related species (O. australiense, O. palense, O. indosinense and O. erythrogrammon) revealed differences which justify the retention of O. caudex as a distinct species. Hence the contention by some authors that O. caudex and O. erythrogrammon are synonymous, appears unjustified. O. griffinl and O. multilineatum may prove to be conspecific with O. caudex. O. kokotoniense and O. stuhlmanni are too poorly known for a detailed comparison     

A Comparative,Quantitative Study of the Micro-Arthropods in Different Types of Pasture Soil

The osmoregulatory abilities of the grapsoid crabs Cyclograpsus punctata*, Sesarma catenata andSesarma eulimene were studied comparatively in an attempt to explain, at least in part, their distribution in estuaries. Both survival and haemorymph osmotic pressure were used as indices of hyperosmotic regulatory ability.

All three species were shown to be capable of regulating their haemorymph osmotic pressure against lowered external salinities. S. eulimene was found to be better able to control its haemorymph concentration in very low salinities than S. catenata, which would account for the former's occurrence in the upper reaches of estuaries. C.punctatus was shown to be capable of roaintaining its haemorymph osmotic pressure above that of the environmental medium in lowered salinities, but without the degree of constancy characteristic of the two Sesarma species. It does, however, show a marked ability to tolerate lowered internal osmotic pressure, an ability which appears to develop in response to partial dilution of the haemorymph. These adaptations, together with its semi-terrestrial habit as a shore crab, suffice to enable C. punctata* to penetrate an estuary to almost the same extent as S. catenata.     

The southern African stichopodid holothurians,with notes on the changes in spicule composition with age in the endemic Neostichopus grammatus (H.L. Clark)

Four species of stichopodid holothurians, namely the Indo-West Pacific Stichopus chtoronotus Brandt, S. variegatus Semper, Thefenota anax H.L. Clark and the endemic Neostichopus grammatus (H.L. Clark) occur in the southern African shallow waters (south of 20°S latitude). Besides T. anax, which is not present in the material studied, notes are provided on the remaining three species, of which S. variegatus is here recorded from this region for the first time. The changes with age in the composition of the body wall spicules of N. grammatus are described and it is indicated that the characteristic dumb-bell-shaped deposits of the dorsal papillae, consistent in both juveniles and adults, offer a reliable and easily accessible morphological character in preserved specimens. A key to all four species is provided and their geographic distributions are mapped.     

Molecular phylogenetics reveals a complex history underlying cryptic diversity in the Bush Squeaker Frog (Arthroleptis wahlbergii) in southern Africa

Throughout the Miocene, the African landscape underwent broad climatic shifts that profoundly influenced the distribution of fauna and flora. Since the late Miocene, these shifts have created a landscape in southern Africa that is strongly characterised by savanna and arid environments. Forests persist in small fragments, primarily in mountainous or heterogeneous landscapes. Arthroleptis wahlbergii is a small frog endemic to eastern South Africa that has presumed low dispersal ability. Because of its preference for forests, the dynamics of forests since the late Miocene in this region might have promoted diversification within A. wahlbergii. To investigate whether habitat fragmentation might have driven divergences among populations, we carried out species distribution modelling and population level and phylogenetic analyses using two genetic loci (16S, mitochondrial; RAG-1, nuclear) sequenced for 48 individuals from 14 forests across the c. 500 km range of this species. There is substantial population-level structuring within A. wahlbergii, however the structure does not relate to forest types or catchments. We instead propose that the structure is a result of dynamic and idiosyncratic changes in forest connectivity over the Pleistocene. We identified two geographically circumscribed clades, the northern of which corresponds to true A. wahlbergii. The southern clade corresponds to populations from which Arthroleptis wageri FitzSimons, 1930 was described. This has long been considered a synonym of A. wahlbergii, but our molecular phylogenetic and distribution modelling supports recognising A. wageri as a distinct species.     

A Temporal Study of Niche Breadth and Overlap in Two Sympatric Species of Mystacocarida (Crustacea)

Horus is an olpiid pseudoscorpion of which nine species have been described from southern Africa; a tenth, debatable species was described from the Ivory Coast. The two most widely distributed species are H. granulatus and H. obscurus, the former occurring especially in the west and the other in the east, but their distributions overlap; in two instances they have been recorded from the same site. All species have a preference for rock outcrops, which are largely disjunct, and their regular prey comprises small ant species. Fieldwork over a period of 15 years indicated a very low dispersal rate; therefore one would expect localized ‘island’ populations rather than widely dispersed species. This means that the current species delimitations which lump geographically widespread populations may be incorrect. Mitochondrial DNA of specimens from each of 20 different localities across South Africa were analysed to test the hypothesis. Five of these localities did not yield results, but 14 yielded DNA from specimens which proved to belong to Horus and a fifteenth turned out to be a misidentified pseudoscorpion unrelated to Horus. The results were unequivocal: populations from each locality or group of closely-spaced localities were genetically distinct from any other one tested, and the greater the distance between localities, the greater the genetic differences (i.e. significant isolation by distance). This means that the current species delimitations for Horus are incorrect. It will require detailed micro-anatomical study to identify new characteristics on which species delimitations can be based in future.     

>Utilization of shallow subtidal bays associated with warm temperate rocky shores by the late-stage larvae of some inshore fish species,South Africa

>This work describes the utilization of shallow, subtidal bays, associated with rocky shores, by the late-stage larvae and early juveniles of some common inshore fishes. Larval and early juvenile fishes were collected in seven small bays (30–50 m wide) between Port Alfred (33°36’S, 26°53’E) and Hamburg (33°17’S, 27°29’E), using a modified, beach seine net (500 µm mesh). Four bays were sampled weekly during peak fish spawning (September–November 2004) to firstly assess whether larval fishes occur in these previously-unstudiedhabitats and secondly, to assess the extent of this utilization in terms of species occurrence, abundance and potential nursery function. An additional three replicate bays, situated >50 km away near Bira were used for comparison. In total, 14 fish families represented by 26 taxa were recorded but the catch was dominated by a small suite of common species. Bays were extensively utilized by Sparidae (>Diplodus capensis >and >Sarpa salpa>), and to a lesser extent by Clinidae (>Clinus superciliosus>), Mugilidae (>Liza >spp.) and Kyphosidae (>Neoscorpis lithophilus>). Mean CPUE of larvae was high and exceeded 900 individuals per seine haul. Larval abundance peaked at 4000 larvae per haul and at these times, was dominated only by the two sparid species. Abundance of sparid larvae exceeds that recorded for these species in surf zones, estuaries or the shallow nearshore habitatssampled to date in temperate South Africa by an order of magnitude. Larval abundance was significantly higher during new moon sampling throughout the study period, but was not significantly different between repeated samples collected per site on each fieldtrip. The length-frequency of larvae utilizing the bays was dominated by postflexion stages ranging 7–14 mm SL. Length-frequency distribution of >Diplodus, Sarpa, Clinus, Sparodon, Neoscorpis >was indicativeof grow-out and use of bays as interim nurseries. The nursery function of these bays is supported by gut analysis of a sub-sample of the dominant species, >Diplodus capensis, >which showed that these larvae were actively feeding in the area, predominantly on copepods. This work prompts further research on shallow habitats associated with rocky shores particularly the shelter and feeding role that these under-studied habitats are playing in the early life history of coastal fishes.     

On the Behaviour of the Crabeater Seal Lobodon Carcinophagus (Hombron & Jacquinot)

The sharp-nosed reed frog is widespread in Africa. Although currently recognized as one species, suggestions have been made that more than one species might exist. We analysed 237 calls of 69 males from 19 localities in the western to southern parts of Africa. Calls fall into three groups, which we recognize as cryptic species. Of eight published sound spectrograms, all can be assigned to one of the three species. We recognize Hyperolius nasutus, distributed from western Africa to the Okavango Delta in Botswana; Hyperolius viridis, from the central highlands of northwestern Zambia to southern Tanzania; and Hyperolius acuticeps> which occurs from the Ivory Coast to the southeastern coast of South Africa. We assign published names to the synonymies of these three species. No call data are available for populations in the Congo basin.     

Larval development of the Cape silverside,Atherina breviceps Cuv. & Val., 1835 (Teleostei,Atherinidae) from southern Africa

The egg and larval development of the Cape silverside, Atherina breviceps, are described and illustrated from material collected in the Swartvlei estuary. The eggs are spherical, 1,40-1,65 mm in diameter, with 6-12 uniformly spaced chorionic filaments attached at both ends to the chorion. TTie latter condition and the small size of the eggs are unique among the Atherina species. The larvae examined (5,1-15,7 mm) are elongate, have a yolk sac at hatching and are characterized by distinct body pigmentation and a prominent gas bladder. Flexion occurs between 7,6-11,2 mm, all fin elements are formed by 15,7 mm and scales develop by 20,0 mm. We compare the larval development of A breviceps with that of other atherinids and discuss the spawning of this species and the seasonal occurrence of larvae along the southern coast of Africa.     

The phyllophorid holothurians of southern Africa with the erection of a new genus

The southern African dendrochirotid holothurians of the family Phyllophoridae (sensu Pawson & Fell, 1965) are revised and a new genus Thyonina is erected to accommodate Thyone articulata Vaney, 1908, which possesses only slender spectacle-shaped rods as body wall deposits. In addition, Thyone proceracorona Cherbonnier, 1952 and T. turrisolida Cherbonnier, 1954, are declared junior subjective synonyms of T. aurea (Quoy & Gaimard, 1833); Havelockia imperfecta Cherbonnier, 1970 is transferred to the genus Thyone, and T. venusta Selenka, 1868 (synonym T. okeni Bell, 1884) is recorded for the first time from southern Africa. These changes bring the total number of phyllophorid holothurians now known from southern Africa to five genera and 11 species. All species are keyed, briefly described and/or discussed, and their local distributions mapped.     

Trial by fire: social spider colony demographics in periodically burned grassland

Nature conservation authorities in southern Africa burn the grassland in nature reserves to reduce the incursion of woody plants and to encourage the growth of new grass for grazing. Studies have shown significant negative effects of burning on the abundance, species diversity and community composition of smaller vertebrates and invertebrates. Social arthropods are likely to suffer from repeated burning, as destruction of the colony means a permanent loss of the entire reproductive unit. Nests of social spiders of the genus Stegodyphus (Eresidae) are a prominent feature of African savannas and their size and visibility make them potentially good indicators of ecological consequences of fire. The colonies are sedentary and their nests may persist for several years, although individuals have an annual life cycle. We explored the mortality patterns and the effects of burning on survival of colonies of two species of social spider, Stegodyphus mimosarum and S. dumicola that live sympatrically. We compared colony mortality in burned and unburned areas to determine if colony mortality was due to burning or, alternatively, to natural senescence. Analysis of five years of nest mortality data together with information on the burning regime in Spioenkop Nature Reserve, KwaZulu Natal province (South Africa), indicates that colony extinction in S. mimosarum is independent of the burning regime, while burning is a significant cause of colony mortality in S. dumicola. The different responses of the two species are likely a result of different colony dynamics and nesting sites.     

Genetic Characterization of Cryptosporidium spp. in Diarrhoeic Children from Four Provinces in South Africa

The diversity of Cryptosporidium at species, subtype family and subtype level in diarrhoeic children was investigated in four provinces in South Africa. A total of 442 stool samples from children <5 years of age were collected under a large rotavirus surveillance programme and analysed by Ziehl–Neelsen acid‐fast staining. Fifty‐four (12.2%) were positive for Cryptosporidium, of which 25 were genotyped by polymerase chain reaction (PCR)–restriction fragment length polymorphism (RFLP) and DNA sequence analyses of the 18S rRNA gene. The majority of genotyped specimens were identified as C. hominis (76%), and a high genetic diversity was found with five different C. hominis subtype families (Ia, Ib, Id, Ie and If). Cryptosporidium parvum was found in 20% of the isolates, and three subtype families were identified (IIc, IIe and IIb), with subtype family IIc being the most common. One specimen was identified as C. meleagridis of the subtype family IIId. These results are in accordance with findings from other developing countries and report for the first time the presence in South Africa of C. meleagridis, various subtypes of C. parvum and the subtype family Ie of C. hominis. The results suggest that C. hominis and anthroponotic C. parvum subtypes are the major cause of cryptosporidiosis in South Africa. Further molecular studies are needed to better understand the epidemiology and public health importance of Cryptosporidium in humans in South Africa.     

The feeding ecology of Ambassidae (Osteichthyes: Perciformes) in Natal estuaries

The diets of three species of Ambassis in six estuaries of southern Africa were investigated using four methods of stomach content analysis. Diets varied from one estuary to another as the faunal composition changed according to physical conditions. Ecological separation among the species is achieved to a large extent through diet alone. While all Ambassis feed mainly on a wide variety of zooplankters, Ambassis productus and A. natalen-sis are also piscivorous and insectivorous respectively. Seasonal analysis of diet showed that A. gymnocephalus feeds mainly on fish eggs during winter (June-August). The possible impact of egg predation on fish numbers at St Lucia is discussed. Feeding periodicity was investigated using dry mass and volumetric methods. All Ambassis showed similar bimodal feeding intensities during the night with peaks in early evening and early morning. Food selection at different levels in the water column showed that all Ambassis feed mainly on food in suspension. Additionally A. natalensis feeds on surface prey while A. productus takes ben-thic prey. It is postulated that interaction between Ambassis and filter-feeding planktivores in St Lucia is minimal due to feeding strategies and feeding periodicity. In addition the impact of the piscivorous predatory role played by Ambassis on estuarine fish communities is emphasized.     

Integrative taxonomy helps to reveal the mask of the genus Gynandropaa (Amphibia: Anura: Dicroglossidae)

Species of the genus Gynandropaa within the family Dicroglossidae are typical spiny frogs whose taxonomic status has long been in doubt. We used integrative methods, involving morphological and molecular analyses, to elucidate the phylogenetic relationships, and to determine identities and the geographic distribution of each valid species. We obtained DNA sequence data of 5 species of Gynandropaa (complete sequences of the mitochondrial NADH dehydrogenase subunit 2 [ND2] gene, and 890 bp of 12S rRNA and 16S rRNA partial sequences) from 37 localities (including the topotypes of 5 described species) and constructed Bayesian and maximum‐likelihood trees to examine the patterns of phylogeography. A total of 28 morphological variables were taken on 624 specimens. Three clades with clear geographic patterns were recognized: clade C (from south‐western Sichuan Province and central Yunnan Province), clade E (western Guizhou Province and eastern to central Yunnan Province) and clade W (western to southern Yunnan Province). Integrating morphological characteristics and distribution information, the clades W, E and C represent Gynandropaa yunnanensis, G. phrynoides and G. sichuanensis, respectively. We draw the following conclusions: (i) the taxon G. phrynoides, formerly evaluated as a junior synonym of G. yunnanensis, is revalidated herein at the rank of species; (ii) G. liui is a junior synonym of G. sichuanensis; and (iii) G. yunnanensis is a valid species while G. bourreti is probably a subspecies of G. yunnanensis, with the distribution range from Vietnam to southern Yunnan Province. This study clears up the taxonomic status of Gynandropaa and provides important information for understanding the evolution and conservation of these spiny frogs.