La afiliación de los trabajadores independientes a la seguridad social en Colombia: el

Parasitism is the close association of two organisms, of which the parasite is dependent on a host and derives some form of benefit (Rohde 2005). Some parasites can display predation, although a true predator kills and eats prey whereas a parasite feeds but often does not kill the host. Some parasitic effects may be detrimental in the long term (Rohde 2005). Parasites also generally form a permanent association with its host, while micropredators rarely form a permanent association (Bruce 2009).

Of the 144 isopod families, few are parasitic and are found in the superfamilies Cryptoniscoidea Kossmann, 1880; Bopyroidea Rafinesque, 1815 and Cymothooidea Leach, 1814. The superfamilies Cryptoniscoidea and Bopyroidea represent approximately 7.7% of described isopods (Williams & Boyko 2012), with nearly 90% known species contained within the Bopyroidea (Markham 1985; Boyko et al. 2014). The Cymothooidea (of the suborder Cymothoida Wägele, 1989) is a polyphyletic taxon which includes all predatory, parasitic, blood-sucking or scavenging isopods. The parasitic cymothooideans include the cymothoids, aegiids, tridentellids, corallanids and gnathiids (Smit et al. 2014; Wetzer 2015). As the level of parasitism increases, setae are fewer (particularly the pereopods and mouthparts), mouthparts develop abrading serrate scales and body segments are smoother (Poore & Bruce 2012).

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1.5.1 The parasitic superfamilies Cryptoniscoidea and Bopyroidea

It is estimated that 3% of all crustacean species are parasites of other crustaceans (Kuris 1974). Bopyroidea and Cryptoniscoidea, referred to as epicarideans, are obligate parasites of other crustaceans (Espinosa-Pérez & Hendrickx 2001). Epicarideans differ from other isopods by the highly modified mouthparts forming a suctorial cone for hemolymph feeding of their crustacean hosts (Boyko et al. 2014). The three families of Bopyroidea are Bopyridae Rafinesque, 1815; Dajidae Sars, 1882; and Entoniscidae Kossmann, 1881. The families are centered on the Indo-West Pacific and likely have the greatest number of undescribed species (Williams & Boyko 2012). The Bopyridae is currently divided into nine subfamilies comprising 605 described species that are exclusively parasitic on decapod hosts (Williams & Boyko 2012). Cryptoniscoids are ectoparasitic on copepods, ostracods, isopods, amphipods, barnacles and mysids (Nielsen & Strömberg 1965). The Cryptoniscoidea contains seven families with approximately 100 described species (Williams & Boyko 2012).

The biodiversity and taxonomy of the epicarideans are still unresolved and require attention. For example, there is evidence that the bopyrid fauna of the Indo-West Pacific may be double the number presently known in that region (Markham 1986; An 2009; An et al. 2010, 2012; Markham 2010; Williams & Madad 2010) and it is anticipated that many more species occur in northern Australia (Poore 2002). Of the 37 known entoniscids (WoRMS 2014), two species occur from Australia, with many species still awaiting description (Shields & Earley 1993). The taxonomic framework of cryptoniscoids is unresolved as families and genera are based on host association rather than morphological characters (Nielsen & Strömberg 1965, 1973).

15 1.5.2 The cymothooidan parasites

The seven families included in Cymothooidea according to the classification of Brandt & Poore (2003) are Aegidae White, 1850; Anuropidae Stebbing, 1893; Corallanidae, Hansen, 1890; Cymothoidae Leach, 1818; Gnathiidae Leach, 1814; Protognathiidae Wägele & Brandt, 1988 and Tridentellidae Bruce, 1984. One further family, the Barybrotidae Hansen, 1890, was re-validated by Bruce (2009). The two non- parasitic families are the Protognathiidae and Anuropidae, whereas the five other families show progressive development towards parasitism. The protognathiids (two species in the genus Protognathia) are mesopelagic species found in the Antarctic and Southern Oceans (Wӓgele & Brandt 1988). The anuropids (10 species in the single genus Anuropus) are bathypelagic species found in the Caribbean and Pacific Ocean (Beddard 1886).

There are 155 species of Aegidae, of which 33 are known from Australian waters (ABRS 2009). Aegids are micropredators rather than parasites of fishes, generally feeding on blood meal and are not permanently attached to their hosts (Bruce 2009).

Alitropus typus Milne Edwards, 1840 is probably the most common aegid reported attacking fishes in India and Southeast Asia in fresh and brackish waters (Rohde 2005). Species from the genus Rocinela, may attach for longer periods to their hosts (see examples in Novotny & Mahnken 1971; Wing & Moles 1995; de Lima et al. 2005).

The Tridentellidae consists of 21 species in the genus Tridentella and is known from the Pacific and Atlantic Oceans (WoRMS 2014). Tridentella saxicola (Hale, 1925) is the only known species to occur in Australia (ABRS 2009), although six species are present in the nearby Indo-Pacific. Several tridentellids are fish ectobionts in their free- living state (Bruce 1984). The mouthparts appear well adapted for rasping and piercing into host flesh (Bruce 1984). Species within the genus can be separated by differences in cephalon, posterior pereonites, pleonites and pleotelson morphology (Bruce 1984, 2008).

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The Gnathiidae is cosmopolitan with 222 species in 12 genera (WoRMS 2014), of which 56 species in seven genera occur in Australia (ABRS 2009). Holdich & Harrison (1980) and Cohen & Poore (1994) reviewed the family for the Australian fauna, with further species contribution from Coetzee et al. (2008, 2009), Ferreira et al. (2009, 2010), Farquharson et al. (2012) and Svavarsson & Bruce (2012). The adults are benthic isopods whereas the juvenile ‘pranizas’ are ectoparasitic on fishes (Svavarsson 2006). The taxonomy relies on male characters as females and juveniles are not easily identified (Brusca et al. 2001). Recently though, Wilson et al. (2011) were able to illustrate taxonomically useful traits from juvenile species to aid identification (e.g. shape of the cephalon, eyes and uropod setation) as well as morphometrics of total body expansion of the pereon after blood feeding.

The Corallanidae consists of 80 species in six genera, with the genus Corilana

considered to be nomen dubium. Delaney (1989) provided a world review of the family, which included keys to the genera, phylogeny of the family and the biogeography. The Australian corallanids consist of 15 species from five genera (ABRS 2009), mostly reviewed by Bruce (1982 a, b). Cirolanids are chiefly marine species that are benthic, with few that inhabit freshwater and estuarine environments. Corallanidae includes micropredators and temporary parasitic species, mostly on fishes. The species Tachaea caridophaga (Riek, 1953)and Excorallana tricornis occidentalis Richardson, 1905 are to date the only known corallanids to parasitize crustaceans (Riek 1967; Guzman et al. 1988).

The Cymothoidae consists of 383 species within 40 genera (Smit et al. 2014), of which 71 species in 17 genera are found in Australia (ABRS 2009). Cymothoids are obligate parasites of fishes and exhibit high host and site specificity (Trilles 1969, 1994; Brusca 1981; Bunkley-Williams & Williams 1998a). The family is ubiquitous except in the polar waters and has a high diversity in tropical regions (Brusca 1981; Bakenhaster

et al. 2006). The Australian fauna was reviewed by Bruce (1986, 1987a, b, c, 1990, 1991) which resolved the complex taxonomy of the Anilocrinae and gill- and branchial- attaching genera. The buccal-attaching genera, particularly in Australian waters, remained unrevised, with many species of doubtful or unclear identity (Poore 2002).

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