Microdrilia trina, copyright Muséum National d’Histoire Naturelle.

Belongs within: Borsoniidae.

Microdrillia is a genus of small conoids known from the Indo-Pacific and Caribbean (Powell 1966).

Characters (from Powell 1966): Shell small, 2.3–14 mm, claviform, with tall spire, and truncated anterior end. Protoconch narrowly conical of about five whorls, tip smooth, remainder axially costate. Sculpture of strong smooth spiral keels. Sinus area sunken between heavy subsutural and peripheral keels; whole of fasciole conspicuously sculptured with numerous concavely arcuate growth threads, marking successive positions of moderately deep rounded sinus. Outer lip thin; anterior canal very short and weakly notched. Radula, where known, consisting of pair of awl-shaped marginals with expanded base.

<==Microdrillia Casey 1903BK11 [incl. Acrobela Thiele 1925BW80, Acropota Nordsieck 1977BK11]
    |--*M. cossmanni (Meyer 1887)BW80 [=Pleurotoma cossmanniBW80; incl. P. meyeri Cossmann 1906P66]
    |--M. biplicatula Casey 1903P66
    |--M. circumvertens (Melvill & Standen 1901) [=Drillia circumvertens]P66
    |--M. citrona Harris 1937P66
    |--M. commentica (Hedley 1915)P66 [=Drillia commenticaP66, Turridrupa commenticaH22]
    |--M. ‘difficilis’ (Smith 1879) [=Pleurotoma difficilis non P. difficile Giebel 1864]P66
    |--M. elongatula Casey 1903P66
    |--M. fastosa (Hedley 1907)BK11 [=Pleurotomella fastosaP66, Turridrupa fastosaH22]
    |--M. harrisi (Aldrich 1895) [=Glyphostoma harrisi; incl. M. aldrichiella Casey 1903]P66
    |--M. hebetica Gardner 1937P66
    |--M. infans (Meyer 1886) [=Pleurotoma infans]P66
    |    |--M. i. infansP66
    |    `--M. i. bicincta Harris 1937P66
    |--M. minutissima Casey 1903P66
    |--M. niponica (Smith 1879) [=Pleurotoma niponica]P66
    |--M. optima (Thiele 1925)BK11 [=Bela (*Acrobela) optimaBW80, *Acropota optimaBW80]
    |--M. ouachitae Harris 1937P66
    |--M. pakaurangia Powell 1942P66
    |--M. patricia (Melvill 1904) [=Pleurotoma (Oligotoma) patricia]P66
    |--M. propetrina Mansfield 1925P66
    |--M. robustula Casey 1903P66
    |--M. rostratula Casey 1903P66
    |--M. sansibarica (Thiele 1925) [=Bela (Acrobela) sansibarica]P66
    |--M. solidula Casey 1903P66
    |--M. steiroides (Chapman & Crespin 1928) [=Filodrillia steiroides]P66
    |--M. stephenensis Laseron 1954P66
    |--M. tersa Woodring 1928P66
    |--M. trina Mansfield 1922P66
    |--M. triporcata (Smith 1879) [=Pleurotoma triporcata]P66
    `--M. vicksburgella Casey 1903P66

*Type species of generic name indicated


[BK11] Bouchet, P., Y. I. Kantor, A. Sysoev & N. Puillandre. 2011. A new operational classification of the Conoidea (Gastropoda). Journal of Molluscan Studies 77: 273–308.

[BW80] Bouchet, P., & A. Waren. 1980. Revision of the north-east Atlantic bathyal and abyssal Turridae (Mollusca, Gastropoda). Journal of Molluscan Studies Supplement 8: 1–119.

[H22] Hedley, C. 1922. A revision of the Australian Turridae. Records of the Australian Museum 13 (6): 213–359, pls 42–56.

[P66] Powell, A. W. B. 1966. The molluscan families Speightiidae and Turridae: an evaluation of the valid taxa, both Recent and fossil, with lists of characteristic species. Bulletin of the Auckland Institute and Museum 5: 1–184, pls 1–23.

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