Two new species of Gastrosaccus (Crustacea Mysidacea) from sandy beaches in Transkei

Volume: 76Start Page: 309End Page: 32

Doxomysis algoaensis, a new mysid species (Crustacea: Mysidacea) from Algoa Bay (South Africa)

Doxomysis algoaensis sp.nov. is described from Algoa Bay, South Africa where it is common in nearshore marine waters just beyond the breaker line. D. algoaensis sp.nov. is morphologically similar to D. australiensis, but can readily be distinguished by the shape and armature of the telson and the length of the exopod of the fourth male pleopod. The apical cleft is one fifth the telson length in the former species and one third the length in D. australiensis. The telson apex on each side of the cleft is also armed with five and four stout spines in the two species, respectively. In D. australiensis, the exopod of the fourth male pleopod is almost three times the length of the endopod; in D. algoaensis sp.nov., the exopod is only slightly longer than the endopod. Other distinctive features of D. algoaensis sp.nov. include the maxillary palp, which is only slightly broader than long and the greater number of spines on the endopod of the uropod

Diversity of benthic macrofauna of the flood-tidal delta of the Nahoon Estuary and adjacent beach, South Africa

Macrobenthos of the Nahoon estuarine flood-tidal delta was surveyed to determine species composition, distribution and abundance; establish possible patterns in community structure and compare assemblages with those of adjacent sandy beach and lower estuary. Macrozoobenthos retained by a 1 mmmesh was collected by  sampling four 1m2 replicates, at 14 sites in the flood-tidal delta using a suction-sampler and at three sites on the beach by digging quadrats. A total of 118 species was identified: 106 in the flood-tidal delta and 36 on the beach. Major taxa were: Crustacea 60 species, Mollusca 20, Polychaeta 27, Insecta 6, Pisces 3.  Maximumdensity was 5171m2 (Urothoe serrulidactylus). Species richness  decreased from beach to river mouth and increased from mouth sites to sites  furthest from the mouth. In all areas, species richness increased from high shore to low shore. Multivariate analyses of species abundances identified four groups of sites, showing a gradual change in community structure from the beach into the estuary. Species analyses identified indicator species of these groups. The flood-tidal delta had a characteristic set of species, some of which were largely restricted to this area, while others occurred more abundantly on the beach or in the estuary. Several typical sandy beach species were more abundant in the flood-tidal delta than on the beach. Sites furthest from the mouth were characterized by  estuarine species.Key words: macrobenthos, open estuary, beach, intertidal ecology.

Mysidacea from the Comoros archipelago with descriptions of two new species

Volume: 112Start Page: 89End Page: 10

A NEW SPECIES OF GASTROSACCUS (MYSIDACEA) FROM WESTERN AUSTRALIA

Volume: 13Start Page: 129End Page: 13

A new species of Gastrosaccus (Crustacea, Mysidacea) from Algoa Bay (South Africa)

Gastrosaccus wittmanni sp. nov. was collected from surface-waters near Kings Beach in Algoa Bay (South Africa). Morphologically, it is characterised by having seven strong spines on each side of the telson. In between the strong spines, spinules are present except between the first most proximal pair. The endopod of the first female pleopod bears one terminal plumose seta. Most of the setae on antennules, antennae, thoracopods, pleopods and uropods are jointed

Affinities of some common estuarine macroinvertebrates to salinity and sediment type: Empirical data from Eastern Cape estuaries, South Africa

Fourteen species of subtidal macrobenthos present in thirteen Eastern Cape  estuaries, South Africa, were compared with regard to correlations with two  important environmental variables (salinity and sediment mud content). Species were divided into five different faunal components based on their affinity with one of the two variables, namely marine species, oligohaline species, estuarine sand species, estuarine mud species, and species whose distribution seemed independent of either environmental variable. Although most species exhibited wide tolerance ranges to both environmental variables, preference ranges could be identified in many cases. Among the fourteen species studied, three were found mostly at high salinities, two were confined to sandy substratum, and four showed a clear preference for muddy sediment. The crab  Paratylodiplax algoense was identified as a euryhaline marine species and the larvae of chironomid midges, previously believed to be oligohaline species, were found to be tolerant to near seawater salinities.Key words: subtidal macrobenthos, true estuarine species, estuary, salinity,  substratum

Idiomysis mozambicus, a new mysid species (Crustacea: Mysidacea) from Mozambique

Idiomysis mozambicus is described from coastal waters of Mozambique. The species can be distinguished from the other species of the genus by the one-segmented antennal scale, the two-segmented exopod of the fourth male pleopod and the bluntly pointed rostrum

A new species of Gastrosaccus (Crustacea, Mysidacea) from beaches in Madagascar

Gastrosaccus madagascariensis sp.nov. is common in the surfzone of sandy beaches along the east and south coasts of Madagascar. Morphologically, it is characterised by having seven lateral spines along each side of the telson; with spines 2-4 and the penultimate spine being dorso-lateral in origin. One or two spinules are interspersed between the fifth and terminal spines. The fourth exopod segment of pleopod 3 in the male is bulbous, bearing two terminal barbed unequal spines. A robust and naked seta is also present on the same segment in the male