• Protentelloides dalhousiei Zhang and Scott, 1995:77, pl. 1, figs. 12a-d [upper Oligocene Zone P22, DSDP Hole 366A, eastern equatorial Atlantic Ocean].
• Clavatorella aff. C. oveyi Buckley, 1974.—Spezzaferri, 1994:50, pl. 36, figs. 5a-c and 6a-c [upper Oligocene Zone P22, ODP Hole 667A, eastern equatorial Atlantic Ocean].

This species exhibits a very wide range of morphological variability in the shape of the final chamber or bulla and the structure and complexity of the aperture system. The test is superficially planispiral (pseudoplanispiral), however, unlike Eocene Hantkenina and Pseudohastigerina that are truly planispiral (biumbilicate), umbilical and spiral sides are recognizable due to asymmetry of the apertural lip on the two sides, which rotates slightly into the umbilicus. Protentelloides dalhousiei has a similar wall texture to G. atlanticus. Pore density in P. dalhousiei is much lower than in G. variabilis and G. stainforthi.  [Coxall & Spezzaferri 2018]

Like its ancestor Protentelloides primitivus, this taxon has not been recorded since its description in 1995, or outside its type locality in the eastern equatorial Atlantic Ocean. We recognize it as a distinct species that represents a branch of the Globorotaloides lineage. Described from DSDP Site 366 (Zhang and Scott, 1995), this morphology was recorded informally as Clavatorella aff. C. oveyi Buckley by Spezzaferri (1994) from the equivalent level (Zone O7) in ODP Site 667, 150 km to the northeast of Site 366. The Site 366 sequence has been restudied for the purposes of this work. Together with Protentelloides primitivus, P. dalhousiei has been suggested as an accessory marker for recognizing the Oligocene/Miocene boundary in tropical settings (Zhang and Scott, 1995) (see below), however, this is of limited use because it has not been found elsewhere (e.g. Leckie and others, 1993; Spezzaferri, 1994; Pearson and Chaisson, 1997). Moreover, Spezzaferri (1994) who recorded this morphotype as Clavatorella aff. C. oveyi at nearby ODP Site 677, indicate the range of Protentelloides (species undifferentiated) to extend sporadically across the Oligocene/Miocene boundary up to Zone N4 (lower Miocene Zone M1 of Berggren and others, 1995).  [Coxall & Spezzaferri 2018]

Zhang and Scott (1995) tentatively suggested Protentelloides dalhousiei as the ancestor of Clavatorella bermudezi (Bolli). This is based on a single specimen of C. bermudezi recorded (not illustrated) occurring 8-9 m above the highest occurrence of Protentelloides spp. in DSDP Hole 366A, still within Zone O7 (Zhang and Scott, 1995:82, Table 1). Oligocene to Miocene biostratigraphic studies of DSDP Hole 366A by Krasheninnikov and Pflaumann (1977), however, record ‘(rare) C. bermudezi only’ in the upper part of the lower Miocene (Praeorbulina glomerosa Zone) (= M4/M5, Berggren and others, 1995), and middle Miocene (Orbulina suturalis-Globorotalia peripheroronda and Globorotalia peripheroacuta zones = M6), which is consistent with the range of this species based on observations from other sites (Quilty, 1976; Spezzaferri, 1994; Pearson and Chaisson, 1997). The single specimen is described as being “well-preserved…and… thin-walled” (Zhang and Scott, 1995:82). This is inconsistent with the heavily cancellate wall of Clavatorella and is instead suggestive of Quilty’s (1976) species Quiltyella nazcaensis described from the Oligocene (Zones N2-N4 = O4-O7 of Wade and others, 2011) in the equatorial Pacific Ocean (see Chapter 6, this volume). Based on this reasoning we conclude that the range of Protentelloides and C. bermudezi do not overlap, and thus, that P. dalhousiei is not the ancestor of C. bermudezi but that Zhang and Scott’s (1995) specimen is a rare, protentelloidid homeomorph (as indicated by the higher stratigraphic range of the morphotype recorded at Site 667, Spezzaferri, 1994) or possibly Quiltyella nazcaensis, which is related to Globigerinella (see Chapter 6, this volume). This trend of becoming digitate, as we presume Zhang and Scott’s C. bermudezi to be, occurs repeatedly in a variety of Eocene to Recent low latitude tropical taxa (Coxall and others, 2007). [Coxall & Spezzaferri 2018]

Protentelloides dalhousiei is a rare but conspicuous species. It differs from Protentelloides primitivus from which it evolved in the more evolute coiling, near-planispiral coiling, less conspicuous inner whorl, equatorially centered final chamber and primary aperture, and the great variability and complexity of the apertural system, including the tendency to become ‘cribrate’. It differs from all other globorotaloidids in the tendency to form a cribrate aperture system. It can also be distinguished from Globorotaloides hexagonus, to which some forms bear a close resemblance, by its tendency to possess an equatorial-umbilically positioned bulla-like final chamber. Also by the nature of the primary aperture, which possess distinctive lips, as well as, commonly, accessory apertures. There is a tendency for the final chambers of P. dalhousiei to become slightly radially elongate, but as not dramatically as in Clavatorella bermudezi Blow, 1965, and Protentella Lipps, 1964. [Coxall & Spezzaferri 2018] 

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