D. Christopher Rogers

Cladocera and Other Branchiopoda

Publisher Summary This chapter focuses on the class Branchiopoda, which includes the common Daphnia, and other members of the suborder Cladocera (order Diplostraca). Branchiopods are a heterogeneous group linked by similar mouthparts and leaf-like thoracic legs (phyllopods). Virtually all species within the eight extant orders of Branchiopoda are limited to inland waters (mostly freshwater lentic systems). Branchiopods occupy key positions in aquatic communities. As consumers, they are algivorous herbivores, detritivores (often assimilating bacteria on benthic or suspended organic matter), and occasionally predators of small invertebrates. They are important prey items in the diets of many fish, waterfowl, and certain other vertebrate and invertebrate predators. Many species are planktonic while others live in shallow water benthic habitats. Some, like the fairy shrimp Artemia , are adapted to temporary ponds and to hypersaline ponds and lakes. Scientists estimate that the United States and Canada contain ∼645 species of cladocera and nearly 100 species of the generally larger, noncladoceran branchiopods. This chapter introduces the general biology, morphology, phylogeny, evolution, ecology, physiology, and classification of Branchiopods, with focus on those found in freshwaters of North America.

Global diversity of large branchiopods (Crustacea: Branchiopoda) in freshwater

With about 500 known species worldwide, the large brachiopods are a relatively small group of primitive crustaceans. With few exceptions they live in temporary aquatic systems that are most abundant in arid and semi arid areas. As many regions remain unexplored and as especially the number of species in clam shrimps and tadpole shrimps is underestimated due to difficult identification, the species list will increase with future surveys. The Branchiopoda are monophyletic, but inter-ordinal relationships, as well as many evolutionary relationships at lower taxonomic levels are still unclear. Ongoing molecular studies will more accurately depict species diversity and phylogenetic patterns. With the exception of some anostracan families, most families are not restricted to the northern or southern hemisphere or specific zoogeographical regions. Large branchiopods are used for the assessment of the quality and function of temporary wetlands. Due to the reduction in number and quality of temporary wetlands, several species became endangered and are red listed by the IUCN.

REVISION OF THE EXTANT GENERA OF LIMNADIIDAE (BRANCHIOPODA: SPINICAUDATA)

ABSTRACT The extant genera of the spinicaudatan clam shrimp family Limnadiidae are revised using morphological criteria built on previously published molecular analyses. The combined analyses demonstrate the presence of eight well defined genera, two of which are new to science and one (Paralimnadia) that is resurrected. We present the description of the new genus Afrolimnadia and the new genus and species Calalimnadia mahei n. sp. described from Mauritius Island. Both molecular and morphological data strongly support eight genera: Afrolimnadia n. gen., Calalimnadia n. gen., Eulimnadia, Imnadia, Limnadia, Limnadopsis, Metalimnadia and Paralimnadia.

Larger hatching fractions in avian dispersed anostracan eggs (Branchiopoda)

Anostracan crustacean eggs were collected from various materials leaving and entering branchiopod habitats. The eggs were cultured from allochthonous dust and mud, bird faeces and stomach contents. Eggs that passed through aquatic bird digestive tracts hatched in significantly larger fractions than eggs dispersed by other vectors and eggs from resident habitat egg banks. Predator dispersed eggs would necessarily have a greater chance of reaching suitable habitat than eggs that are randomly dispersed (such as by wind). This larger hatching fraction would amplify the priority effects of habitat monopolisation should the eggs be deposited in unoccupied habitat.

19 – INTRODUCTION TO THE SUBPHYLUM CRUSTACEA

Crustaceans are the most diverse of any group of arthropods and currently thrive in a wide array of habitats. Most species occur primarily in aquatic habitats but some are adapted to live on land. The fossil record extends back to the lower Cambrian and throughout most of this long period, crustacean fossils are associated with a broad range of aquatic habitats, especially marine waters. Crustaceans have evolved into several major groups that represent distinct modifications for exploiting resources and performing ecosystem services in many different surface waters and subsurface habitats. Amphipods and isopods, as well as mysids and branchiura are discussed in this chapter. Crustacean zooplankton are major consumers of phytoplankton and they transfer energy from these primary producers up the food web to zooplanktivorous fish in lakes, ponds, and rivers. Some crustacean zooplankton also consume aggregations formed from dissolved organic matter and other organic particulates. Others are predatory on rotifers, protozoans, other crustaceans, aquatic insects, and fish eggs and larvae. Some zooplankton vertically migrate and thereby link deep, benthic habitats with open waters of lakes. These migratory species are important in nutrient cycling and transfers of toxins (such as heavy metals and pesticides) from sediments to pelagic food webs.

A New Giant Species of Predatory Fairy Shrimp from Idaho, USA (Branchiopoda: Anostraca)

Abstract A previously unknown species of giant fairy shrimp is described. Branchinecta raptor n. sp. is highly adapted to a predatory mode of life. In both sexes, the first four pairs of thoracopods bear elongated, curved, heavily chitinized endopods, which are modified for grasping prey. Both sexes have elongated, “whip-like” cercopods nearly as long as the abdomen that are used for detecting prey. This new species appears most closely related to B. gigas Lynch 1937. Both species are large in size, have small eyes and sensory papillae, and share similar habitats and food preferences. However, B. raptor has some unusual predatory behaviors that differ from B. gigas. B. raptor is separated from all other Branchinecta by the unique form of the second antennae, the form of the cercopods, and the male genitalia. Large branchiopod records from Idaho are also discussed.

A Conceptual Model for Anostracan Biogeography

A conceptual model for anostracan biogeography based on the “Monopolisation Hypothesis” and the “Theory of Island Biogeography” is discussed and presented. In this model anostracan species evolve allopatrically (in geographically isolated, unoccupied insular habitats), cladogenically (in small, genetically isolated founder populations via strong priority effects), or anagenically through local adaptation to changing environmental conditions. The Monopolization Hypothesis drives speciation and reverses competitive dominance patterns, leading to selection mediated priority events. Conversely, the spatial distribution of anostracan habitats (basins) drive island biogeographical patterns depending upon the relative isolation and size of any one given pool. The conceptual model presented provides a simple framework for future research in anostracan biogeography.

Female-based characters for anostracan (Crustacea: Branchiopoda) identification: A key for species of California and Oregon, USA

Anostracan identification keys and descriptions tend to focus on characteristics of males, specifically on structures associated with the second antennae, which are modified to amplex the female prior to mating. Many female anostracans have an amplexial groove with which to receive the males second antennae. The amplexial groove, dorsal ornamentation, and the form of the brood pouch have characteristics that can be used in species identification. To demonstrate this, and to aid in surveys for rare, threatened and endangered forms, a female based identification key for anostracan species known to occur in California and Oregon, USA, is presented.

Fairy Shrimp (Branchiopoda: Anostraca) of Chile

Abstract Portions of Chile were surveyed for Anostraca. Including the two species of Artemia previously reported from Chile, we found 5 new localities and range extensions for 5 species of Branchinecta. Previous studies on Chilean Anostraca have focused on Artemia, and although Branchinecta was previously reported in Antarctica close to Chilean Air Force installations, and in a few temporal ponds in Southern Patagonia, the species were never determined. Brief habitat descriptions, as well as conservation status, and identification keys are presented and discussed. Additionally, we describe a new species from the Atacama Desert, Branchinecta papillata n. sp.

A morphological re-evaluation of the anostracan families Linderiellidae and Polyartemiidae, with a redescription of the linderiellid Dexteria floridana (Dexter 1956) (Crustacea: Branchiopoda)

Previous molecular studies proposed that the Linderiellidae and Polyartemiidae should be subsumed into the Chirocephalidae. In an attempt to find morphological evidence to support this assertion, I compared the genital morphology for representative genera of the Linderiellidae, Chirocephalidae and Polyartemiidae. Penal morphology of the anostracan genera Linderiella and Dexteria appear to form a continuum between the Chirocephalidae and the Polyartemiidae. Furthermore, due to the limited information presented in the original description, Dexteria floridana is redescribed from type material.