Mictacea

Abstract: A new genus and species, Hlrsutia bathyalis, created for a single, small peracaridan crustacean collected at a depth of 1,000 m from the sea floor off northeastern South America, provides the basis for one of two new families, the Hirsutiidae, of the new Order Mictacea erected by Bowman et al. (1985). Hirsutia uniquely possesses a number of morphological features found neither in other peracaridan orders nor in the second species, Mictocaris halope, and family, the Mictocarididae, of the Mictacea (Bowman and Iliffe, 1985). These include paragnaths that have elongate, slender anterior extensions that are probably sensory; an absence of grooming armature on the medial surface of the mandibular palp; unusually long setal armature on the pereiopodal basal-endopodal shaft relative to other peracaridan Crustacea; "oostegites" that arise from the posterior rather than the medial surface of the coxa as in all other known Peracarida, supporting Claus's (1885) century-old contention that oostegites are modified epipodites. Certain morphological features of Hirsutia suggest that it possesses the potential of being a facultative carnivore.

Abstract: From the biogeographic viewpoint, marine caves on oceanic islands represent ‘islands within islands.’ Due to the isolation and environmental stability of this habitat, such caves act as refuges, preserving primitive relict taxa. Investigations of marine caves in the Atlantic have resulted in the discovery of many higher taxa including the new crustacean class Remipedia (Yager, 1981), the new peracarid order Mictacea (Bowman and Iliffe, 1985), the new copepod order Platycopioida (Fosshagen and Iliffe, 1985), the new isopod family Atlantasellidae (Sket, 1979) and the new caridean family Agostocaridae (Hart and Manning, 1986). Unexpectedly however, the troglobitic (i.e., cave-limited) fauna of Atlantic marine caves show highly anomalous biogeographical distributions, as well as close taxonomic affinities to deep sea species. Particularly noteworthy in this regard is the fauna of the Jameos del Agua, a marine lava tube cave in the Canary Islands. Members of six crustacean genera inhabiting this cave, including the remipede Speleonectes, the anthurid isopod Curassanthura, the amphipod Spelaeonicippe, the mysid Heteromysoides, the ostracod Danielopolina, and the thermosbaenacean Halosbaena, also have species inhabiting caves on the western side of the Atlantic. This amphi-Atlantic distribution suggests that these taxa are Tethyan relics having an origin in caves early in the history of the Atlantic and subsequently dispersed by plate tectonics and sea floor spreading (Iliffe et al., 1984; Wilkens et al., 1986). Also from the same cave, the galatheid crab Munidopsis polymorpha and the polynoid polychaete Giesiella jameensis belong to groups known primarily from the deep sea.

Abstract: A new species very similar to Hirsutia bathyalis Sanders et al. (1985), the only other member of the Hirsutiidae, is described from 1,500 m off southeastern Australia. The single specimen has oostegite-like appendages with long, plumose marginal setae. Their posterior position is compared with a similar position in siphonoecetine amphipods. Pereiopod 1 has the usual number of articles. The terminal position of the anus on the telson is contrasted with the position in Mictocaris, the only other mictacean known. The structure of the limbs and mouthparts of Hirsutia suggests a selective deposit-feeding habit. The peracaridean order Mictacea was created by Bowman et al. (1985) in order to encompass two simultaneously described species: Hirsutia bathyalis Sanders, Hessler, and Garer, 1985 (placed in a new family Hirsutiidae), from the central western Atlantic off Surinam at 1,000 m, and Mictocarls halope Bowman and Iliffe, 1985 (in the new family Mictocarididae), from marine caves on Bermuda. Hirsutia bathyalis was based on one preparatory female, now badly digested, and a juvenile exuviae, now lost; and M. halope on 55 specimens. We report on a third specimen of Hirsutia

Abstract: Anchialine caves are tidal, subterranean, inland habitats with a salinity-stratified water column and exchange of saltwater with the sea. They primarily occur on oceanic islands and some peninsulas with karstic limestone or volcanic terrain and include some of the longest explored caves on Earth. Use of specialized scientific cave-diving technology is essential to access this environment. A diverse, specially adapted fauna, dominated by crustaceans and other invertebrates, inhabit deeper, euhaline waters in anchialine caves. A number of new higher taxa, e.g., class Remipedia and order Mictacea, exclusively occur in this habitat. Some groups of anchialine fauna are found on opposite sides of oceans or even opposite sides of the Earth, and others have close relatives in the deep sea. Chemoautotrophically based food webs have been identified providing food in the otherwise lightless and nutrient-limited cave environment. Investigations of anchialine caves and their fauna by diving are a recent development so that much work remains. Only a small percentage of anchialine caves have been explored, much less scientifically studied, suggesting many new discoveries still wait.