Holocystites scutellatus, from here.

Belongs within: Diploporita.

The Aristocystitidae are a group of Lower Ordovician to Middle Silurian cystoids characterised by having the brachioles arising from facets directly adjacent to the mouth, with ambulacra exceedingly short.

Characters (from Kesling 1967): Theca ovate to elongate, typically tapered or constricted at aboral end, containing numerous, irregularly arranged plates. Column small and degenerate where present, absent in most forms. Most pores confined to one plate, canals simple, irregularly branched, or regularly divided to form typical diplopores. Brachioles arising from facets adjacent to mouth; ambulacra very short and unbranched, scarcely developed in some.

<==Aristocystitidae [Aristocystiden]
    |--Campylostoma Dreyfuss 1939 K67
    |    `--*C. grandis Dreyfuss 1939 K67
    |--Pseudaristocystis Sun 1936 [=Dagoncystis Chauvel 1941] K67
    |    `--*P. dagon (Bather 1906) [=Aristocystis dagon, *Dagoncystis dagon] K67
    |--Lepidocalix Termier & Termier 1950 K67
    |    `--*L. pulchrus Termier & Termier 1950 [=L. pulchrum] K67
    |--Amphoracystis Haeckel 1896 K67
    |     `--*A. irregularis (Barrande 1887) [=Deutocystites irregularis] K67
    |--Hippocystis Bather 1919 K67
    |    `--*H. subcylindrica (Barrande 1887) [=Aristocystites bohemicus subcylindricus] K67
    |--Baculocystites Barrande 1887 K67
    |    `--*B. simplex Barrande 1887 K67
    |--Trematocystis Jaekel 1899 K67
    |    |--*T. subglobosa (Miller 1889) [=Holocystites subglobosus] K67
    |    `--T. hammelli K67
    |--Pachycalix Chauvel 1936 K67
    |    |--*P. halli (Rouault 1851) [=Calix halli] K67
    |    `--P. pachythecus K67
    |--Calix Rouault 1851 [incl. Dorycystites Kloucek 1917] K67
    |    |--*C. sedgwicki Rouault 1851 K67
    |    |--C. lebesconti K67
    |    |--*Dorycystites’ purkynei Kloucek 1917 K67
    |    `--C. rouaulti K67
    |--Sinocystis Reed 1917 [incl. Ovocystis Reed 1917] K67
    |    |--*S. loczyi Reed 1917 K67
    |    |--S. mansuyi (Reed 1917) [=*Ovocystis mansuyi] K67
    |    |--S. segaudi K67
    |    `--S. yunnanensis K67
    |--Aristocystites Barrande 1887 [=Aristocystis Bather 1889] K67
    |    |--*A. bohemicus Barrande 1887 [=*Aristocystis bohemicus; incl. Aristocystites grandiscutum Barrande 1887] K67
    |    |--A. desideratus K67
    |    |--A. gigas K67
    |    |--A. regularis K67
    |    |--A. rudis K67
    |    `--A. sinicus K67
    `--Holocystites Hall 1864 [=Holocystis Carpenter 1891, Megacystis Angelin 1878, Megacystites Hall 1865] K67
         |--*H. cylindricus (Hall 1861) (see below for synonymy) K67
         |--H. abnormis K67
         |--H. adipatus K67
         |--H. affinis K67
         |--H. alternatus K67
         |--H. amplus K67
         |--H. baculus K67
         |--H. benedicti K67
         |--H. brauni K67
         |--H. canneus K67
         |--H. colletti K67
         |--H. commodus K67
         |--H. dyeri K67
         |--H. elegans K67
         |--H. faberi K67
         |--H. globosus K67
         |--H. gorbyi K67
         |--H. greenvillensis K67
         |--H. gyrinus K67
         |--H. indianensis K67
         |--H. madisonensis K67
         |--H. ornatissimus K67
         |--H. ornatus K67
         |--H. ovalis K67
         |--H. papulosus K67
         |--H. parvulus K67
         |--H. parvus K67
         |--H. perlongus K67
         |--H. plenus K67
         |--H. pustulosus K67
         |--H. rotundus K67
         |--H. scitulus K67
         |--H. scutellatus K67
         |--H. spangleri K67
         |--H. sphaericus K67
         |--H. sphaeroidalis K67
         |--H. splendens K67
         |--H. subovatus K67
         |--H. subrotundus K67
         |--H. tumidus K67
         |--H. turbinatus K67
         |--H. ventricosus K67
         |--H. wetherbyi K67
         |--H. winchelli K67
         `--H. wykoffi K67

*Holocystites cylindricus (Hall 1861) [=Caryocystites cylindricum, *Holocystis cylindrica, *Megacystis cylindrica, *Megacystites cylindricus] K67

*Type species of generic name indicated


[K67] Kesling, R. V. 1967. Cystoids. In Treatise on Invertebrate Paleontology pt. S. Echinodermata 1. General characters. Homalozoa-Crinozoa (except Crinoidea) (R. C. Moore, ed.) vol. 1 pp. S85-S267. The Geological Society of America, Inc., and The University of Kansas: Lawrence (Kansas).

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