• Globigerina semivera Hornibrook, 1961:149-150, pl. 23, figs. 455-457 [lower Miocene G. trilobus trilobus Zone, Rifle Butts Fm., Awamoan Stage, Campbells Beach, South Island, New Zealand].
• Globorotalia (Turborotalia) nana semivera (Hornibrook).—Jenkins, 1971:125-127, pl. 12, figs. 342-344 [holotype re-illustrated from Hornibrook, 1961, pl. 23, figs. 455-457].
• Globorotalia semivera (Hornibrook).—Berggren and Amdurer, 1973, pl. 27, figs. 16-19 [lower Miocene Zone N4 and Zone N5, DSDP Site 18, South Atlantic Ocean].—Jenkins, 1977:308, pl. 4, figs. 5-7 [lower Miocene G. trilobus trilobus Zone, English Channel].—Jenkins, 1978, pl. 1, figs. 23, 24 [lower Miocene G. trilobus trilobus Zone, DSDP Site 360, eastern South Atlantic Ocean].—Berggren and others, 1983, pl. 3, figs. 4, 5, pl. 4, fig. 1 [lower Miocene Zone N5 and Zone N6, DSDP Site 516, Rio Grande Rise, western South Atlantic Ocean].—Hoskins, 1984, figs. 7:1-6 [lower Miocene G. trilobus trilobus Zone, Awamoan Stage, New Zealand].
• Globorotalia (Jenkinsella) semivera (Hornibrook).—Kennett and Srinivasan, 1983:172, pl. 42, figs. 3-5 [lower Miocene Globorotalia miozea Zone, DSDP Site 206, New Caledonia Basin, western South Pacific Ocean].
• Paragloborotalia semivera (Hornibrook).—Premoli Silva and Spezzaferri, 1990:304, pl. 3, figs. 8a-c [lower Miocene Zone N4, ODP Hole 709B, Madingley Rise, western equatorial Indian Ocean].—Spezzaferri, 1994:55-56, pl. 20, figs. 6a-c [upper Oligocene Subzone P21b, ODP Hole 709B, Madingley Rise, western equatorial Indian Ocean], pl. 22, figs. 1a-c [lower Miocene Zone N5, DSDP Hole 526A, Walvis Ridge, eastern South Atlantic Ocean].—Morgans and others, 2002, fig. 14P [lower Miocene P. incognita Zone, Altonian Stage, North Island, New Zealand].—Li and others, 2003a:23, pl. 1, fig. 23 [lower Miocene Zone SAN2, ODP Hole 1134B, Great Australian Bight, Indian Ocean], pl. 1, fig. 24 [lower Miocene Zone SAN3, ODP Hole 1134A, Great Australian Bight, Indian Ocean].—Li and others, 2003b:16, pl. 2, fig. 24 [upper Oligocene Subzone P21b, ODP Hole 1134A, Great Australian Bight, Indian Ocean], pl. 2, fig. 25 [upper Oligocene Zone P22, ODP Hole 1134A, Great Australian Bight, Indian Ocean].
• Paragloborotalia semivera (Hornibrook) – Paragloborotalia acrostoma (Wezel).—Spezzaferri, 1994, pl. 22, figs. 2a-c [lower Miocene Zone N5, DSDP Hole 526A, Walvis Ridge, eastern South Atlantic Ocean].
• Paragloborotalia mayeri s.l. (Cushman and Ellisor).—Chaisson and Leckie, 1993:164-165, pl. 8 (partim), figs. 16, 17 [lower Miocene Subzone N4b, ODP Hole 806B, western equatorial Pacific Ocean]. [Not Cushman and Ellisor, 1939.]
• Paragloborotalia pseudocontinuosa (Jenkins).—Li and others, 2003b:16, pl. 2, fig. 26 [lower Oligocene Zone P18-P19, ODP Hole 1134A, Great Australian Bight, Indian Ocean], pl. 2, figs. 27, 28 [upper Oligocene Zone P22, ODP Hole 1134A, Great Australian Bight, Indian Ocean]. [Not Jenkins, 1967.]

Hornibrook (1961) originally placed semivera in Globigerina on account of the umbilical tendency of the aperture. Jenkins (1967:1070) had stated that “G. siakensis is very close in morphology to G. nana semivera and may prove to be synonymous with it.”, but we recognize a clear distinction between siakensis and semivera. Chaisson and Leckie (1993) and Leckie and others (1993) had lumped P. semivera into a broader concept of P. mayeri s.l.; the ‘semivera’ form is restricted to the upper Oligocene of ODP Hole 803D and basal Miocene of Hole 806B. Jenkins (1977) suggested that acrostoma is a junior synonym of semivera, but we consider the two taxa to be unique and not directly related. [Leckie et al. 2018]

Hornibrook (1961) described semivera as having a relatively flat spiral side, three whorls with 4-4½ chambers in the final whorl, radial sutures and a wide umbilical to extraumbilical aperture bordered by a lip. However, Jenkins (1971) and Spezzaferri (1994) used a taxonomic concept based on 4½-5  chambers in the final whorl, with radial to slightly curved sutures on both the spiral and umbilical side. Specimens with 4-4½ chambers in the final whorl closely resemble pseudocontinuosa. Jenkins (1971) stated that most of the paratypes in the original type sample have 4 chambers in the final whorl, which he classified as G. (T.) nana pseudocontinuosa Jenkins. Jenkins (1971) also noted a complete range of variation between the two (sub)species in the type sample, an observation also made by examining semivera topotypes at the Natural History Museum in London (this study). Paragloborotalia semivera is differentiated from P. pseudocontinuosa by its somewhat larger size and in possessing more chambers within the final whorl. Both taxa are gradational throughout their ranges. Paragloborotalia semivera differs from opima in having a high loop-shaped aperture and moderate spire.

Paragloborotalia semivera is distinguished from acrostoma by its more compact, embracing chambers, higher spiral-side convexity, and by its lower arched aperture. It is differentiated from both siakensis and mayeri by having a higher, more convex spiral side, subcircular, less ovate equatorial outline, and a more compact test with more embracing chambers and a narrow, closed umbilicus. It is further differentiated from siakensis by having more embracing chambers and a less lobulate test and a higher arched aperture, and from mayeri in having less recurved sutures on the spiral side and fewer (typically 5 compared with 5½-6) chambers in the final whorl. In some cases P. semivera had been included within the taxonomic concept of mayeri and/or siakensis (Leckie and others, 1993; Chaisson and Leckie, 1993; Pearson and Wade, 2009) and pseudocontinuosa (Jenkins and Srinivasan, 1986). [Leckie et al. 2018]

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