During a zooplankton study in southern China, Streptocephalus specimens were collected from ephemeral ponds located in the Yunnan Province and the Guangxi Zhuang Autonomous Region. We determined that the specimens from both locations are Streptocephalus sirindhornae Sanoamuang, Murugan, Weekers, and Dumont, 2000. This documents are the first records of Streptocephalidae in China, which represent its northern and easternmost distributional edge in East Asia. All specimens are deposited in Kunming Natural History Museum of Zoology, Kunming Institute of Zoology (KIZ), Chinese Academy of Sciences (CAS). The morphological terminology follows Rogers and Padhye (2014) and the material is compared with the original description (Sanoamuang et al., 2000).
Adults of three fairy shrimp species are present in Thailand from February through June in ephemeral waters (ponds, roadside canals, and rice field ditches) filled mostly by the rain. Branchinella thailandensis is of interest in aquaculture because it reproduces rapidly and has high nutritional value. However, no detailed studies on its reproductive biology are available. Anatomical analyses of male and female genitalia were studied with light microscopy and SEM. Shrimp were reared in the laboratory at |$28 \pm {1^\circ }{\text{C}}$| in aerated, potable water using the alga Chlorella sp. as food. One female and two males were placed in each of ten 1-L observation containers and the female reproductive stages were monitored every hour over six days. Branchinella thailandensis exhibits zygogenetic reproduction and oviparity, where fertilization is direct and internal; the brood pouch shows an undifferentiated amplexial groove. Males and females reach maturity on days 7 and 8 after hatching, with a mean standard length of 10.3 and 12.2 mm, respectively. Males have unique spines on the gonopods, with a tip on a socket-like base; accessory glands were not evident in histological sections. Females have biramous ovaries; the shell glands are organized in two paired, bilateral clusters, in which the glandular unit is formed by two gland-cells and a single duct. After six complete reproductive cycles, the mean total duration of the reproductive cycle was |$\sim24.0\;{\text{h}}\;({\text{N}} = 60)$|. The total duration of the reproductive cycle and egg production increased with age (subsequent reproductive cycles). No oösorption in unmated females was observed, and the oöcytes passed to the ovisac independent of copulation. Our results confirmed that Stage 3 is the longest reproductive stage in anostracan females. Branchinella thailandensis produces typical freshwater anostracan sculptured eggs, and belongs to the fairy shrimp group without a sub-cortical space beneath the egg shell.
The only species of the genus Triops in Australia, T. australiensis, is found to reproduce by gonochorism. Morphological and reproductive data and molecular analyses of fragments of mitochondrial genes 12S rRNA (12S) and cytochrome oxidase I (COI) indicate that a Triops population from the middle Paroo in north-western New South Wales is composed of two different entities, Triops cf. australiensis lineage A, and T. cf. australiensis lineage B. Gonad histology in individuals with ovisacs of lineage A revealed no evidence of testicular tissue; however, large testicular lobes were found in individuals with ovisacs of lineage B, indicating that they were anatomically hermaphrodites. This is the first record of Australian hermaphroditic Triops. For each lineage, a single haplotype of each gene was obtained. Molecular genetic distance and phylogenetic analyses confirmed the closer relationship and monophyly of the two lineages with T. australiensis (GenBank) when compared with Triops species from other continents. COI haplotypes of lineage A and lineage B differed by 7.7% from each other and differed by 10.2% and 9.6% from a published T. australiensis sequence, respectively. The 12S haplotypes of lineage A and lineage B differed by 3.3% from each other and differed by 2% and 2.5% from a published T. australiensis sequence, respectively. Our results suggest that the two co-occurring Triops lineages probably represent two species that are distinct from T. australiensis.
In this review, we include rotifers, copepods, and cladocerans, including other groups not usually deemed as zooplankters: i.e., protists, acari, and large branchiopods. The objectives of this study were to integrate the dispersed literature on the taxonomy and diversity of these freshwater zooplankton groups and to explain (1) how these contributions can be arranged in distinct historical periods and (2) how this knowledge has allowed the detection of exotic and threatened species. We divided the freshwater zooplankton studies in Mexico into three historical periods: the first one comprised the 1840s to the 1940s when foreign researchers carried out most studies during several expeditions. Spanish researchers promoted surveys on different zooplankton taxa at the end of this first period. The second period, from the early 1950s to the end of the 1990s of the XX century, showed a remarkably increased research activity in its last ten years only (that is, during the 1990s to 2000), represented by contributions of a new generation of Mexican zooplanktologists. This period yielded more complete zooplankton listings and detailed morphological descriptions of rotifers, cladocerans, copepods, and large branchiopods. The third period started from the year 2000 to date. During this time, listings and online faunistic baselines based on integrative taxonomy have been the primary trend. An account of exotic zooplankters and conservation issues of several native species are discussed. The results of this review show that the knowledge of the freshwater zooplankton of this country has increased significantly over the last 40 years, with at least 408 first records of species for Mexico. Currently, the knowledge of Mexican freshwater zooplankton is among the most complete in the world. However, it is estimated that only a small fraction of the true diversity has been documented.
23 March 2020 in Revista Mexicana de Biodiversidad
To date 86 species of 33 genera and 16 families of Oniscidea have been recorded in Mexico. Collections of 4 academic institutions and recent field materials were revised. From 1,820 specimens, 1,417 (77.6%) were determined to belong to 6 exotic forms. A taxonomic account and a species identification key with SEM plates of these exotic entities are presented. For morphological analysis we used light and SEM microscopy. The molecular identity of 5 of the 6 forms was examined through cytochrome oxidase 1 gene (mtDNA) analyses. The exotic species determined are: Armadillidae, Cubaris murina; Armadillidiidae, Armadillidium vulgare; Porcellionidae, Agabiformius lentus, Porcellio laevis, P. scaber, and Porcellionides pruinosus. The exotic oniscideans were recorded from urban, rural and natural (riparian) zones in 15 states of northern Mexico, including the first formal records in Aguascalientes,Chihuahua, Durango, and Zacatecas. Armadillidium vulgare, P. laevis, and P. pruinosus often co-occurred and are the most widely distributed species in this region. Although most of the material examined was recorded from urban zones(> 50% of studied sites), A. vulgare and P. laevis were also found in riparian areas (natural zones), yet P. pruinosus was recorded mainly from riparian areas (60% of 45 lots examined).