Order MYODOCOPIDA Sars, 1866

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Regional Maps

Introduction

The Myodocopida are distinguished from the Halocyprida by three main features: the (usual) presence of a lateral eye, a fifth limb modified for feeding (rather than walking), and a seventh limb that is usually long (not reduced or absent) (Horne et al. 2002). There are two suborders: Paleomyodocopina (no extant species) and Myodocopina (Kornicker and Sohn 2000).

Diagnosis

Carapace mostly 1–3 mm long (but some large forms up to 32 mm), usually well calcified, shape elongate-ovate or ovate (few rather circular), with or without keel. Carapace sexual dimorphism sometimes very marked. Anterior rostrum and incisure usually well developed, not above mid-height, sometimes weakly developed or absent. Valves smooth or ornamented with pits, reticulation, ribs, alae, nodes, tubercles and spines all possible. Anterior infold with one to many setae. Hinge usually adont or not developed, but sometimes with interlocking teeth and sockets. Valve overlap minimal. Adductor muscle scars: numerous, variable, often aggregated without well-defined pattern, sometimes in approximately circular or ovate aggregation, or arranged in sub-vertical rows converging dorsally. Normal pores both simple and sieve-type. Always with 7 pairs of limbs and furca; male additionally with paired copulatory limbs, female with paired genital apparatus (=reduced limb pair). Seta-like abdominal process posterior to furca may be present or absent. Antennula 7–8-segmented. Endopod of antenna 1–3-segmented, often forming reflexed clasper in male; exopod 9-segmented. Mandibula without large teeth; coxal endite spiny or serrate lobe. Maxillula and fifth limb both short (not leg-like). Sixth limb short, flattened, poorly jointed. Seventh limb usually present, long vermiform cleaning appendage, unsegmented but with numerous annulations (sometimes reduced or absent in males). Male copulatory limbs paired, most with 3 lobes. Compound lateral eyes, median naupliar eye and Bellonci organ (not bifurcate) usually present.

ID Keys

A key to families is presented in Cohen et. al. (2007).

Diagnosis References

Cohen, A.C., Peterson, D.E., & Maddocks, R.F. 2007. Ostracoda. pp. 417-446 in Carlton, J.T. The Light & Smith Manual: Intertidal Invertebrates from Central California to Oregon. Berkeley & Los Angeles : University of California Press 4.

Horne, D.J., Cohen, A. & Martens, K. 2002. Taxonomy, morphology and biology of Quaternary and living Ostracoda. Geophysical Monograph 131: 5-36 [29]

General References

Horne, D.J., Cohen, A. & Martens, K. 2002. Taxonomy, morphology and biology of Quaternary and living Ostracoda. Geophysical Monograph 131: 5-36

Kornicker, L.S. & Sohn, I.G. 2000. Myodocopid Ostracoda from the late Permian of Greece and a basic classification for Paleozoic and Mesozoic Myodocopida. Smithsonian Contributions to Paleobiology 91: 1-33

History of changes