Right and left valves of Libumella walkerorum, from Hoare & Merrill (2004).

Belongs within: Palaeocopida.

The Aparchitidae are a group of ostracods known from the Lower Ordovician to the middle Upper Carboniferous. The type genus, Aparchites, is known from the Lower Ordovician to the Middle Devonian and characterised by a generally swollen carapace with the hinge line distinctly shorter than the carapace and the cardinal angles distinctly obtuse (Benson et al. 1961).

Characters (from Benson et al. 1961): Carapace nonsulcate, inequivalved, largely amplete; adductor muscle scar not visible exteriorly or indistinct but may also be well defined; velar structure developed as low ridge which may be tuberculate, extending along ventral border and in some along part of end borders or entire free border; subvelar area channeled; dimorphism not observed.

|--Longidorsa rectelloides Schallreuter 1985WSB93
|--Brevidorsa devonica Reynolds 1978WSB93
|--Macronotella Ulrich 1894BB61
| `--*M. scofieldi Ulrich 1894BB61
|--Neoaparchites Bouček 1936BB61
| `--*N. obsoletus (Jones & Holl 1865) [=Primitia obsoleta]BB61
|--Aparchitellina Polenova 1955 (n. d.)M61, BB61
| `--*A. decorata Polenova 1955BB61
|--Coeloenellina Polenova 1952M61
| `--*C. parva Polenova 1952M61
|--Ginella Ivanova 1960 [=Pinella Ivanova 1955 non Stephenson 1941]M61
| `--*G. tenuispina (Ivanova 1955) [=*Pinella tenuispina]BB61
|--Zaborovia Polenova 1952 (n. d.)M61, BB61
| `--*Z. obscura Polenova 1952BB61
|--Cyathus Roth & Skinner 1930 non Haller 1768 (ICBN)CB86
| |--*C. ulrichi Roth & Skinner 1930BB61
| |--C. caperatus (Guan 1978) [=Sinocoelonella caperata]CB86
| `--C. formosus Shi 1982CB86
|--Saccelatia Kay 1940 [=Saccaletia]BB61
| |--*S. arrecta (Ulrich 1894) [=Aparchites arrectus]BB61
| |--S. arcamuralisBB61
| `--S. bullataBB61
|--Aparchites Jones 1889BB61
| |--*A. whiteavesi Jones 1889BB61
| |--A. crossotusBB61
| |--A. diuturnusNU83
| |--A. fimbriatusBB61
| |--A. kauffmanensisBB61
| `--A. messleriformisB94
| |--A. m. messleriformisB94
| `--A. m. instabilis Polenova 1974B94
|--Libumella Rozhdestvenskaja 1959HM04
| |--L. bonapartensis Jones 1989HM04
| |--L. cribrosa Robinson 1978HM04
| |--L. discoides Rozhdestvenskaja 1959HM04
| |--L. reticulata Robinson 1978HM04
| `--L. walkerorum Hoare & Merrill 2004HM04
`--Baltonotella Sarv 1959B94
|--*B. kuckersiana (Bonnema 1909)B94
|--B. circulantis (Harris 1957) [=Paraparchites circulantis]B94
`--B. parsispinosus (Kraft 1962) [=Aparchites parsispinosus]B94

*Type species of generic name indicated


[B94] Becker, G. 1994. A remarkable Ordovician ostracod fauna from Orphan Knoll, Labrador Sea. Scripta Geologica 107: 1–25.

[BB61] Benson, R. H., J. M. Berdan, W. A. van den Bold, T. Hanai, I. Hessland, H. V. Howe, R. V. Kesling, S. A. Levinson, R. A. Reyment, R. C. Moore, H. W. Scott, R. H. Shaver, I. G. Sohn, L. E. Stover, F. M. Swain & P. C. Sylvester-Bradley. 1961. Systematic descriptions. In: Moore, R. C. (ed.) Treatise on Invertebrate Paleontology pt Q. Arthropoda 3: Crustacea: Ostracoda pp. Q99–Q421. Geological Society of America and University of Kansas Press.

[CB86] Chen D.-Q. & Bao H. 1986. Lower Permian ostracodes from the Chihsia Formation of Jurong and Longtan, Jiangsu Province. Acta Micropalaeontologica Sinica 3 (2): 107–132.

[HM04] Hoare, R. D., & G. K. Merrill. 2004. A Pennsylvanian (Morrowan) ostracode fauna from Texas. Journal of Paleontology 78 (1): 185–204.

[M61] Moore, R. C. 1961. Supplement—USSR treatise on Ostracoda. In: Moore, R. C. (ed.) Treatise on Invertebrate Paleontology pt Q. Arthropoda 3: Crustacea: Ostracoda pp. Q422–Q429. Geological Society of America and University of Kansas Press.

[NU83] Norris, A. W., & T. T. Uyeno. 1983. Biostratigraphy and paleontology of middle-upper Devonian boundary beds, Gypsum Cliffs area, northeastern Alberta. Geological Survey of Canada Bulletin 313: 1–65.

[WSB93] Whatley, R. C., D. J. Siveter & I. D. Boomer. 1993. Arthropoda (Crustacea: Ostracoda). In: Benton, M. J. (ed.) The Fossil Record 2 pp. 343–356. Chapman & Hall: London.

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