Myodocopid Ostracoda of Pillar Point Harbor, Half Moon Bay, California

Kornicker, Louis S.; Harrison-Nelson, Elizabeth

doi:10.5479/si.00810282.593

Cited by 7 publications

(12 citation statements)

References 4 publications

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“…Euphilomedes are generally subtidal philomedid ostracods, commonly found along the Eastern Pacific coast of North America (Smith 1952;Poulson 1962;Kornicker and Harrison-Nelson 1997;Bergen et al 2001). While Kornicker and Harrison-Nelson (1997) did not observe any lateral eyes in females, we observe small rudimentary eyes in females. These eyes are small compared with the male eyes of corresponding stages and are relatively lightly pigmented when viewed alive or preserved in glycerol.…”

Section: Introductioncontrasting

confidence: 51%

“…All of these stages generally resemble the adult, with a full complement of limbs and major features (Hiruta 1980). A notable exception to this is the development of the lateral compound eyes (Kornicker and Harrison-Nelson 1997). Unlike other ostracods whose eyes develop as embryos (Cohen 1983), the eyes of male Euphilomedes are without obvious ommatidia until late in juvenile ontogeny.…”

Section: Introductionmentioning

confidence: 99%

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Ontogeny of sexual dimorphism via tissue duplication in an ostracod (Crustacea)

Rivera

Oakley

2009

Evolution and Development

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The adaptive significance of specific sexual dimorphism is well studied. However, the evolutionary history and ontogenic origins of the dimorphism are often unknown. As dimorphism represents two phenotypes generated from relatively similar genotypes, it is of interest to understand both its evolutionary and developmental/genetic underpinnings. Here, we present the first ontogenetic examination of the eyes of philomedid ostracods (Crustacea), which exhibit extremely sexually dimorphic lateral eyes. Adult male philomedids have large compound lateral eyes, whereas females have rudimentary lateral eyes. First, we show that eye dimorphism is unlikely to be due to additional genes present on a male-specific chromosome because karyotype analysis suggests philomedids are XX/XO. We then examine the ontogeny of eye development and find that in at least two species of Euphilomedes, this dimorphism is not generated solely by differences in tissue growth rates, as has been commonly shown for sexually dimorphic characters of other species. Instead, the dimorphism appears to arise during development via tissue duplication, where a single tissue becomes two, perhaps with different developmental potentials. The second eye field is only observed in male Euphilomedes, producing most of the adult eye tissue. We point out that tissue duplication is a developmental process with evolutionary implications because novel characters could evolve via alternative modification of the duplicated fields, analogous to the origin of new genes by gene duplication and alternative modification. Depending on the evolutionary history of the duplicated field, it may have either facilitated or directly caused the observed sexual dimorphism of philomedid ostracods.

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Section: Introductioncontrasting

confidence: 51%

Section: Introductionmentioning

confidence: 99%

Ontogeny of sexual dimorphism via tissue duplication in an ostracod (Crustacea)

Rivera

Oakley

2009

Evolution and Development

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“…The adult male of another potentially dimorphic cypridinid, Vargula seikiguchii, is unknown. In addition to the two rare species with uncertain status, members of the genera Euphilomedes and Philomedes certainly contain males with compound lateral eyes and females with unfacetted lateral eyes (Kornicker, 1992;Kornicker & Harrison-Nelson, 1997). Presumably, the reduced female eyes are a transitional stage between presence and complete absence of female eyes in Philomedes and Euphilomedes, a hypothesis that could be tested with phylogenetic analyses of multiple species in these groups.…”

Section: Extreme Sexual Dimorphism Of Eyesmentioning

confidence: 96%

Myodocopa (Crustacea: Ostracoda) as models for evolutionary studies of light and vision: multiple origins of bioluminescence and extreme sexual dimorphism

Oakley

2005

Hydrobiologia

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Evolutionists often use phylogeny to examine independent evolutionary events in search of generality. Therefore, groups of organisms rich in such independent character transitions are particularly valuable for the study of evolution. With respect to eyes, vision, and light-related characters, one such group is Ostracoda (Crustacea). Phylogenies of ostracods, derived from DNA sequence data and morphological characters, are presented. These inferred relationships largely agree with previous assessments of ostracod phylogeny, with the exception of paraphyletic Philomedidae. Based on methods of character reconstruction using these inferred relationships, different groups of ostracods probably evolved both bioluminescence and extreme sexual dimorphism (females lack eyes, males have large eyes) multiple times. Furthermore, myodocopid ostracods may have evolved compound eyes independently of other arthropods. For these and other reasons, it is proposed that the Ostracoda are an exceptionally important group for studying the evolution of vision-and light-related characters.

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“…This group includes the following species: E. africanus (Klie 1940), E. chupacabra Lum, Syme, Schwab andOakley, 2008, E. cooki Harrison-Nelson andKornicker, 2000, E. corrugatus (Brady 1897), E. ijimai (Kajiyama 1912), E. japonicus (Müller 1890), E. kornickeri Hartmann, 1974, E. longisetus (Juday 1907, E. morini Kornicker and Harrison-Nelson, 1997, E. nodosus Poulsen, 1962, E. pentathrix Kornicker and Caraion, 1977, E. productus Poulsen, 1962, E. sinister Kornicker and Caraion, 1977, E. smithi Poulsen, 1962, and E. walfordi Poulsen, 1962. Of all the species, E. africanus stands apart by the following apomorphic characters: second segment on the female first antenna is very elongated and without a trace of apical bristle, and there is not a single peg opposite to the comb on the seventh limb.…”

Section: Discussionmentioning

confidence: 99%

A new Euphilomedes Kornicker, 1967 (Myodocopida: Philomedidae) from Tasmania with a key to the species of the genus

Karanovic

2010

Mar Biodiv

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Euphilomedes tasmanicus n. sp. is described in this paper. The species was collected from the estuary of the Huon River in Tasmania, Australia. It is most closely related to another Australian species, E. ernyx Kornicker, 1995. They share three rare characters: more than three bristles on the basale of the mandible, more than one bristle on the coxale of the maxilla, and only one bare peg opposite the comb on the seventh leg. They differ in the actual number of bristles on the basale of the mandible, number of furcal claws and the morphology of their carapaces. Both species belong to a group of species of Euphilomedes Kornicker, 1967 having only the third furcal claw secondary (inserted between two primary claws). Euphilomedes africanus (Klie, 1940) is also redescribed here based on the type material from the Zoological Museum in Hamburg. This species is characterized by a long second segment on the endopod of the first antenna of the female, and also, by having no pegs opposite the comb on the seventh leg. The species belongs to a second group of Euphilomedes having furcal claws three and four secondary. Including the new species, the genus has 25 valid species. A key to species, as well as a map of their distribution is presented.

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Myodocopid Ostracoda of Pillar Point Harbor, Half Moon Bay, California

Cited by 7 publications

References 4 publications

Ontogeny of sexual dimorphism via tissue duplication in an ostracod (Crustacea)

Ontogeny of sexual dimorphism via tissue duplication in an ostracod (Crustacea)

Myodocopa (Crustacea: Ostracoda) as models for evolutionary studies of light and vision: multiple origins of bioluminescence and extreme sexual dimorphism

A new Euphilomedes Kornicker, 1967 (Myodocopida: Philomedidae) from Tasmania with a key to the species of the genus

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