• Globoquadrina dehiscens Chapman, Parr, and Collins. Chaisson and Leckie, 1993, pl. 9, fig. 14. 
• Not Globoquadrina dehiscens Chapman, Parr, and Collins, 1934, p. 569, pl. 11, figs. 36a–c.
• Globoquadrina binaiensis (Koch). Spezzaferri, 1994, p. 42, pl. 38, figs. 1a–d, pl. 42, figs. 4a–c.

Stratigraphic range. - U1338A-38X-2, 35–37 cm R U1338A-44X-3, 102–104 cm. The highest occurrence is not currently well constrained. It is abundant up to Zone M5a at Site U1338, with intermittent occurrences to the top of Zone M5b (recorded as Globoquadrina cf. binaiensis in Pälike and others, 2010). The lowest occurrence is in Zone M2 at Site U1337.

Remarks. Dentoglobigerina binaiensis is used as a secondary biostratigraphic marker within Zone M2 (Wade and others, 2011). However, four-chambered forms referred to as Globoquadrina cf. binaiensis were found at Sites U1337 and U1338 (Pälike and others, 2010). To retain the utility of D. binaiensis as a bioevent we have chosen to apply a strict species concept and confine D. binaiensis to the three-chambered forms, consistent with the original description (Fig. 5.3a). This, therefore, necessitates describing the common four-chambered forms that are found in the early Miocene and earliest middle Miocene as a new species.
D. juxtabinaiensis is distinguished from its ancestor D. binaiensis by its greater number of chambers (4 rather than 3) in the final whorl, which are also more wedge shaped. It differs from G. dehiscens by its more circular periphery and lack of umbilical shoulders. Specimens commonly show evidence of a broken ultimate chamber as seen in Figures 6.2 and 6.5. The lip is highly variable and can appear tooth-like in some specimens.
Spezzaferri (1994) recognized these forms as the more evolved D. binaiensis in the early Miocene from the eastern tropical Atlantic Ocean (Site 667) and equatorial Indian Ocean (Site 709). Chaisson and Leckie (1993) also distinguished between the three- and four-chambered specimens of D. binaiensis in their study from the western equatorial Pacific Ocean (Site 806).
Significantly many of our specimens show evidence of spine holes, indicative of a spinose wall texture. Previously, Dentoglobigerina and Globoquadrina have been considered non-spinose (e.g., Pearson and others, 2006).

Phylogeny. Dentoglobigerina juxtabinaiensis evolved from D. binaiensis in the early Miocene by developing four chambers in the final whorl and a more open aperture.

Distribution. Probably restricted to low latitudes; known from the equatorial regions of the Indian Ocean, Atlantic Ocean (Spezzaferri, 1994), and Pacific Ocean (Chaisson and Leckie, 1993; this study).

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