Globigerinoidesella fistulosa

Globigerinoidesella fistulosa (Schubert, 1910)

(Figs 11K–P, 12A–C, F–L, 13, 14B–G, 15D–F, 16F)

1910 Globigerina fistulosa Schubert: 324, text-fig. 2.

1911 Globigerina fistulosa Schubert; Schubert: 100, text-fig. 13a–c.

1933 Globigerinoides sacculifera var. fistulosa (Schubert, 1910); Cushman: [pages not numbered], pl. 34, fig. 6a–c [locality not given].

1954 Globigerinoides sacculifera var. fistulosa (Schubert, 1910); Cushman, Todd & Post: 369, pl. 91, fig. 13.

1954 Globigerinoides sacculifera var. fistulosa (Schubert, 1910); Hamilton & Rex: 792, pl. 254, fig. 14.

1962 Globigerinoides quadrilobatus fistulosus (Schubert, 1910); Belford: 16, pl. 4, figs 7–10.

1962 Globigerinoides quadrilobatus hystricosus Belford: 17, pl. 4, figs 11–14.

1964 Globigerinoides sacculifer fistulosa (Schubert, 1910); Todd: 1084, pl. 290, fig. 6.

1965 Globigerinoides sacculifer fistulosa (Schubert, 1910); Todd: 64, pl. 26, fig. 3a–c.

1966 Globigerinoides quadrilobatus fistulosus (Schubert, 1910); McTavish: 35, pl. 7, figs 14, 17, 18.

1967 Globigerinoides fistulosus (Schubert, 1910); Parker: 154, pl. 21, figs 3, 5, 6, text-fig. 4a–d.

1970 Globigerinoides trilobus fistulosus (Schubert, 1910); Bolli: 579, pl. 1, figs 8–11.

1970 Globigerinoides trilobus ‘A’ (Reuss, 1850); Bolli: 579, pl. 1, figs 12–17.

1972 Globigerinoides fistulosus (Schubert, 1910); Jenkins & Orr (part): 1092, pl. 13, figs 1–4 [not pl. 13, figs 5–9 = T. sacculifer].

1972 Globigerinoides fistulosus (Schubert, 1910); Lamb & Beard (part): 48, pl. 31, figs 4, 7 [not pl. 31, fig. 8 = T. sacculifer].

1973 Globigerinoides fistulosus (Schubert, 1910); Krasheninnikov & Hoskins: 130, pl. 13, figs 10–12.

1974 Globigerinoides fistulosus (Schubert, 1910); Boltovskoy: 704, pl. 5, fig. 16.

1978 Globigerinoides fistulosus (Schubert, 1910); Krasheninnikov & Pflaumann: 625, pl. 4, figs 7–9.

1979 Globigerinoides fistulosus (Schubert, 1910); Takayanagi, Takayama, Sakai, Oda, & Kato: 78, pl. 1, figs 1, 2.

1981 Globigerinoides fistulosus (Schubert, 1910); Saito, Thompson, & Breger: 68–69, pl. 18, figs 1–3.

1983 Globigerinoides fistulosus (Schubert, 1910); Kennett & Srinivasan: 67–68, pl. 14, figs 7–9.

1983 Globigerinoides quadrilobatus fistulosus (Schubert, 1910); Moullade: 526, pl. 1, figs 12, 13.

1985 Globigerinoides trilobus fistulosus (Schubert, 1910); Bolli & Saunders: 197, text-figs 5–11.

1985 Globigerinoides trilobus ‘A’ (Reuss, 1850); Bolli & Saunders: 197, text-figs 22.1–22.3 [note: figures are reproductions of pl. 1, figs 12–14 from Bolli 1970 (see above)].

1985 Globigerinoides fistulosus (Schubert, 1910); Ujiié: 110, pl. 5, fig. 1.

1986 Orbulina quadrilobata (d’ Orbigny, 1846); Fordham: 102, pl. 11, fig. 19.

1987 Globigerinoidesella fistulosa (Schubert, 1910); Loeblich & Tappan: 490, pl. 536, figs 7, 8 [note: figures are reproductions from Jenkins & Orr (1972); pl. 13, figs 2, 3].

1990 Globigerinoides fistulosus (Schubert, 1910); Vincent & Tourmarkine (part): 800, pl. 2, figs 1, 2 [note: not pl. 2, fig. 3 = T. sacculifer].

1991 Globigerinoides quadrilobatus fistulosus (Schubert, 1910): Chaproniere: 212, pl. 3, figs 1–3.

1993 Globigerinoides fistulosus (Schubert, 1910); Chaisson & Leckie: 158, pl. 2, fig. 4.

1994 Globigerinoides quadrilobatus fistulosus (Schubert, 1910); Chaproniere & Nishi: 224, pl. 4, figs 25–27.

1994 Globigerinoidesella bollii Loeblich & Tappan: 107, pl. 207, figs 4–6.

1994 Globigerinoides fistulosus (Schubert, 1910); Perembo (part): pl. 4, fig. 6 [note: not pl. 4, fig. 5 = T. sacculifer].

1995 Globigerinoides fistulosus (Schubert, 1910); Pearson: 59, pl. 5, fig. 7.

2007 Globigerinoides fistulosus (Schubert, 1910); Dowsett & Robinson: 118, pl. 2, fig. 3.

2013 Globigerinoides fistulosus (Schubert, 1910); Hayashi, Idemitsu, Wade, Idehara, Kimoto, Nishi, & Matsui: 98, fig. 6.4a–6.4b.

Description. Type of wall: normal perforate, spinose, cancellate ‘ sacculifer -type’ wall texture. However, note the ‘ sacculifer -type’ wall texture is commonly obscured by a heterogeneous secondary, ‘gametogenic’ calcite, particularly on the distal ends of protuberances. Test morphology: test size large (typically> 0.5 mm), medium trochospire, becoming more highly trochospire in larger specimens, initially involute but coiling later becomes evolute and expansive to accommodate large final chambers; typically four chambers in the final whorl (may be three and a half or rarely four and a half); early chambers globular, inflated, but last chamber or multiple chambers in the final whorl usually become broad and flattened, extended radially and/or tangentially, with one to numerous elongate protuberances of variable size extending outward from test, generally in one plane, forming an extremely lobulate profile; sutures distinct, depressed, straight to slightly curved on both sides; open umbilicus, moderate to large; primary aperture umbilical, may be umbilical-extraumbilical, a broad, low to moderate arch, arch shape often flattened and asymmetrical, with bordering lip or imperforate band; numerous supplementary apertures on spiral side, usually four or five visible, one per chamber, placed at the sutures of the previous chamber and third-previous chamber, the largest of which may also exhibit a lip or imperforate band, smallest supplementary apertures often obscured by infilling and/or secondary calcification.

Note: description derives from the original description and species concept of Schubert (1910, p. 324) and also from Schubert (1911, pp. 100–101), Saito et al. (1981, p. 68) and Kennett & Srinivasan (1983, p. 68), but is here emended.

Remarks. Globigerinoidesella fistulosa is distinguished from the ancestral Trilobatus sacculifer plexus (T. sacculifer, T. quadrilobatus, T. immaturus and T. trilobus) by the presence of one or more elongate protuberances on the final chamber or chambers and its generally larger test size. It is differentiated from other digitate species by its strictly sacculifer - type wall texture and by usually possessing numerous protuberances on individual chambers, rather than just one protuberance per chamber or an elongated chamber.

Type locality. First described from a Globigerina ‘ Marl’ located at Siminis on Djaul Island, just off New Ireland, Papua New Guinea.

Taxonomic history. Schubert (1910, p. 324) named Globigerina fistulosa, commenting on the elongate protuberances as the characteristic feature. Indeed, the derivation of the species name fistulosa is from the Latin ‘ fistula ’ denoting a hollow tube or pipe, where ‘ fistulosa ’ is to bear numerous fistula. The new species was named within a text section devoted to Globigerina sacculifera Brady, 1877 (= Trilobatus sacculifer), and Schubert (1910) probably thought the two morphotypes to be closely related. He illustrated (Schubert 1910, text-fig. 2) the spiral side of a single G. fistulosa specimen, which exhibits distinct protuberances on the final two chambers. In a subsequent publication, Schubert (1911, pp. 100–101, fig. 13) provided further description and illustrations of three other G. fistulosa specimens, also from the New Ireland area of Papua New Guinea. Though it appears no holotype or suite of type specimens was ever designated or deposited for the new species.

After Cushman (1927, p. 87) erected the genus, Globigerinoides, to encompass forms with supplementary apertures on the spiral side, subsequent workers accordingly placed fistulosa into Globigerinoides, often as a subspecies of sacculifer, trilobus or quadrilobatus (see synonymy list). El-Naggar (1971) considered the digitate protuberances to be a genus-level character, thus erecting Globigerinoidesella as a new genus, distinct from Globigerinoides (see above for discussion of Globigerinoidesella).

Belford (1962, pl. 4, figs 7–10) documented Globigerinoides quadrilobatus fistulosus from Papua New Guinea, but also named a new subspecies, Globigerinoides quadrilobatus hystricosus (pl. 4, figs 11–14), which also exhibits protuberances. Most authors place hystricosus in synonymy with fistulosa, as is the case in the present work, but several authors have erroneously used the name ‘ hystricosus ’ to represent intermediate forms with incipient protuberances (i.e. a transitional morphotype with intermediate morphology between sacculifer and fistulosa; e.g. Saito et al. 1981; Hemleben et al. 1987; Loeblich & Tappan 1994). However, Belford’ s (1962) original type figures clearly exhibit large protuberances, rather than a transitional specimen. In fact, Belford (1962) named hystricosus as a new subspecies to account for specimens where the protuberances develop from globular, inflated chambers, rather than from the flattened, sac-like chambers of T. sacculifer. This observation led Belford (1962) to infer two distinct lineages, whereby protuberances developed from T. sacculifer and T. immaturus independently. A sac-like chamber is clearly not a prerequisite for protuberance development; illustrative examples exist in Bolli & Saunders (1985, text-figs 22.5–22.7), Perembo (1994, pl. 4, fig. 6) and this study (Fig. 15A–E). However, these specimens are generally smaller than G. fistulosa sensu stricto; it is likely that the protuberances simply developed earlier in ontogeny and no sac-like chamber was ever developed. Even in G. fistulosa sensu stricto specimens, protuberances develop from both globular chambers and sac-like chambers (see Fig. 13). No evidence is found in this work for two independent lineages. Rather, the observation that protuberance development occurs in more than one member of the T. sacculifer plexus, not just T. sacculifer sensu stricto, is possibly the first substantial fossil evidence to support that they are the same biological species. This corroborates with the culturing (e.g. Hemleben et al. 1987) and molecular genetic (Andŕe et al. 2013) evidence which suggests that all members of the T. sacculifer plexus are the same (biological) species.

Loeblich & Tappan (1994) named a new species, Globigerinoidesella bollii, for morphotypes which form protuberances extending in more than one plane, based on specimens of Globigerinoides trilobus ‘A’ from Bolli (1970) and Bolli & Saunders (1985). Globigerinoidesella bollii is also here considered synonymous with G. fistulosa, and has not been documented in publications after Loeblich & Tappan (1994). Although G. fistulosa does exhibit wide morphological variability, there is little stratigraphical value in delimiting G. fistulosa into multiple morphospecies. Globigerinoidesella is therefore regarded as monospecific, in accordance with El-Naggar (1971) and Spezzaferri et al. (2015).

Protuberance development. Globigerinoidesella fistulosa sensu stricto is a very distinctive taxon, possessing broad, flattened final chambers and finger-like protuberances. These features generally make identification of this species straightforward. However, intermediate forms are present throughout the entire range of G. fistulosa (mid-Pliocene to Pleistocene). In fact, intermediate forms with incipient protuberances occur in cultured specimens and are regularly present in Pleistocene to Recent assemblages (see Fig. 10), although they are much rarer than during the stratigraphical range of G. fistulosa. This observation forms the basis of the delimitation between G. fistulosa and T. sacculifer in this work. Samples from the GLOW Expedition (Kroon & Scientific Participants 2010) are used to determine the maximum protuberance development in Recent T. sacculifer plexus populations as a tool for delimiting the threshold between morphospecies. Since the last occurrence of G. fistulosa is in the early Pleistocene (Zone PT1), protuberance development should not occur in Recent specimens. Figure 10 highlights examples of protuberance development in specimens from the GLOW-3 sample and also from previous culturing studies (B́e et al. 1982; Brummer et al. 1987; Hemleben et al. 1987). These specimens are not considered G. fistulosa, but rather extreme phenotypes of T. sacculifer. Therefore, analogous specimens from the Pliocene–Pleistocene should not be considered G. fistulosa or else the stratigraphical range would effectively be extended to Recent and the biostratigraphical utility lost.

Protuberance development is also associated with thick ‘crust’ development on the distal ends of protuberances, which obscures the primary wall texture (Fig. 14). In many cases the spine holes and pores are completely obscured (e.g. Fig. 14C). However, spine holes were observed on some protuberances (e.g. Fig. 14B). These are the first spine holes discovered on G. fistulosa protuberances, which demonstrate that protuberances were spinose during life. This would have increased the effective size and surface area of the organism and may have enabled larger or more successful prey capture.

As described in the systematic taxonomy, protuberance development can occur on morphotypes that would otherwise be assigned to T. immaturus or T. quadrilobatus. This is illustrated in Figure 15, where single protuberances have developed from spherical final chambers, rather than from sac-like final chambers. Figure 15A and B, C are considered T. quadrilobatus and T. immaturus, respectively, but once protuberance development increases (Fig. 15D–F), the specimens are regarded as Globigerinoidesella fistulosa. Note that these specimens are all from the same sample at Site 1115, and do not indicate an evolutionary bioseries, but rather illustrate the degree of protuberance development that can occur from spherical final chambers. Whilst most protuberance development occurs on sac-like final chambers, this is not a prerequisite, as highlighted by specimens in Figure 15.