Piretellidae

Left and right valves of male Bromidella depressa, from Benson et al. (1961).

Belongs within: Ostracoda.

The Piretellidae are a group of ostracods known from the Ordovician, commonly characterised by a large submedian knob on the valve surrounded by a deep sulcus (Benson et al. 1961).

Characters (from Benson et al. 1961): Amplete or preplete, cardinal angles well defined, S2 permanently distinct (other sulci may be indicated), L2 usually developed as prominent presulcate knob (other lobes generally not present), dorsal plica and lobal crests usually present, generally C1 and C3, which may be united ventrally and, dorsally, with dorsal plica; scattered tubercles present on surface, sometimes seemingly forming indistinct linear patterns; dimorphic, velar ridge or flange in tecnomorphs and incurved frill forming anteroventral closed or almost closed chamber in heteromorphs (frill may be continued posteriorly by isolated spines).

<==Piretellidae
    |–Bolbina Henningsmoen 1953 BB61
    |    `–*B. ornata (Krause 1896) [=Bollia ornata] BB61
    |–Hesperidella Öpik 1937 BB61
    |    `–*H. esthonica (Bonnema 1909) BB61
    |–Piretia Jaanusson 1957 BB61
    |    `–*P. geniculata Jaanusson 1957 BB61
    |–Piretella Öpik 1937 [incl. Duhmbergia Schmidt 1941] BB61
    |    |–*P. acmaea Öpik 1937 BB61
    |    `–P. margaritata BB61
    |–Rakverella Öpik 1937 BB61
    |    |–*R. spinosa Öpik 1937 BB61
    |    `–R. bonnemai BB61
    `–Bromidella Harris 1931 BB61
         |–*B. reticulata Harris 1931 BB61
         |–B. depressa BB61
         `–B. rhomboides BB61

*Type species of generic name indicated

REFERENCES

[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.

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