The synonymies shown here include the first description and representative references that illustrate the development of the species concept for the taxon.
Mesocena oamaruensis apiculata Schulz, 1928, p. 240, fig. 11.
Bachmannocena apiculata (Schulz), Bukry, 1987, pp. 403–404; McCartney and Wise, 1990, pl. 2, figs. 6–10; McCartney and Harwood, 1992, pl. 1, fig. 9.
Remarks: B. apiculata is commonly present in the samples of the lower Miocene and upper Oligocene section of Hole 1219A. The specimens have three equal sides with small spines at each corner.
A single specimen of this taxon in Sample 199-1219A-5H-2, 70–71 cm (36.7 mbsf), is interpreted as reworked.
Cannopilus sphaericus Gemeinhardt, 1931, p. 104, pl. 10, figs. 3, 4.
Remarks: A single specimen of this taxon was found in Sample 199-1219A-10H-4, 70–71 cm (see Ciesielski, 1975, p. 669, pl. 2, fig. 1, and Bukry, 1975b, p. 860, pl. 1, fig. 1, for photographs of a similar specimen). The orientation of the specimen did not allow for precise counting of the basal sides, but the number is probably six or seven. McCartney and Wise (1990) found this morphology to be included within a wide range of variation in Distephanus speculum hemisphaericus, but the specimen found in this study was an isolated occurrence, without D. speculum in the same sample.
Corbisema bimucronata Deflandre, 1950, p. 191, figs. 174–177.
Corbisema bimucronata bimucronata Bukry, 1975b, p. 861, pl. 1, fig. 3.
Remarks: C. bimucronata bimucronata is characterized by having a robust apical structure and a basal ring with blunt corners that are typically bounded by two small spines. The specimens identified in this study are different from those illustrated by Bukry (1975b, 1978a), Perch-Nielsen (1975), and McCartney and Wise (1987) in that they have straighter sides that lack an indentation of the basal ring where the ring attaches to the apical strut.
Corbisema bimucronata rotatoria Bukry, 1978a, p. 696, pl. 1, figs. 6, 7.
Remarks: The specimens are very similar to co-occurring C. bimucronata bimucronata, but each corner has one side that is extended slightly farther than the other side that forms that corner. When the specimen was viewed from the apical center, the right side was consistently extended farther. The taxon ranges from middle Eocene to lower Oligocene, but is especially abundant in a narrow interval from Sample 199-1219A-21H-4, 70–71 cm, to 21H-6, 70–71 cm (191.0–193.7 mbsf).
Corbisema triacantha flexuosa Stradner, 1961, v. 14, no. 2, p. 89, pl. 1, figs. 1–8.
Corbisema flexuosa (Stradner), Bukry, 1975b, p. 853, pl. 1, figs. 4, 5.
Remarks: A single specimen was identified in Sample 199-1219A-23H-4, 70–71 cm (210.7 mbsf).
Corbisema triacantha var. hastata Lemmermann, 1901, p. 259, pl. 10, figs. 16, 17.
Corbisema hastata (Lemmermann), Ling, 1972, p. 155, fig. 5.
Remarks: Specimens of C. hastata were found in the middle Eocene.
Dictyocha triacantha var. inermis Lemmermann, 1901, p. 259, pl. 10, figs. 16, 17.
Corbisema inermis inermis (Lemmermann), Bukry, 1976a, p. 892, figs. 2, 3.
Remarks: C. inermis inermis is a large triangular species with a simple apical structure. Specimens of this study were sporadic and all were found within the Eocene. The specimens of Corbisema inermis found in this study have small spines at the corners (see McCartney and Wise, 1987, pl. 1, fig. 16, for a similar specimen).
Corbisema regina Bukry in Barron et al., 1984, p. 150, pl. 2, figs. 5–13.
Remarks: Specimens of C. regina were present in the middle Eocene and are dominant in Sample 199-1219A-21H-6, 70–71 cm. This taxon was described from the Kellogg Shale of northern California and has been rarely documented in the deep ocean literature. Barron et al. (1984) state that it is common at Site 356, where it was counted as "C. triacantha s. ampl." It has also been found at Sites 406, 553 (Bukry, 1984), 612, 613 (Bukry, 1987), and in Antarctic erratics (Bohaty and Harwood, 2000). The basal ring is very similar to that of C. triacantha, but differs in having small pikes and an apical plate. The specimens found in this study generally had thinner struts than those illustrated by Barron et al. (1984).
Dictyocha triacantha Ehrenberg, 1844, p. 80.
Corbisema triacantha (Ehrenberg), Hanna, 1931, p. 198, pl. D, fig. 1; Bukry and Foster, 1974, p. 305, fig. Ie.
Remarks: This taxon is sporadic from the lower Oligocene to middle Miocene.
Dictyocha byronalis Bukry in Barron et al., 1984, p. 151, pl. 3, figs. 1–4.
Remarks: Specimens of this taxon have an apical structure that is tilted slightly away from the minor axis.
Dictyocha varia f. extensa Locker, 1975, pp. 99–101, figs. 1/2, 3/3.
Dictyocha extensa (Locker), Locker and Martini, 1986, pp. 903–904, pl. 2, figs. 10–12; pl. 11, fig. 3.
Dictyocha extensa extensa (Locker), McCartney et al., 1995, p. 146, pl. 3, figs. 2–5; pl. 5, figs. 3, 7; pl. 8, fig. 8.
Dictyocha ausonia Deflandre, 1950, p. 195, figs. 194–196, 199–202.
Dictyocha brevispina ausonia (Deflandre), Bukry, 1978a, p. 697, pl. 1, figs. 17–19; McCartney et al., 1995, p. 147, pl. 2, figs. 2–4; pl. 3, fig. 11; pl. 5, fig. 4.
Remarks: McCartney et al. (1995) describe the changing interpretation of Dictyocha fibula and propose that D. fibula be applied to four-sided silicoflagellates that have a bridge parallel to the minor axis, and they use D. fibula ausonia, D. fibula fibula, and Dictyocha fibula mutabilis as subspecies. In previous papers, McCartney (see McCartney et al., 1995, for references) followed the usage of Bukry and others in applying this name to four-sided silicoflagellates that had a bridge parallel to the major axis. This paper continues the usage of McCartney et al. (1995), and the reader is referred there for information on these taxa.
Dictyocha fibula Ehrenberg, Locker, 1974, p. 636, pl. 1, fig. 6 (= lectotype).
Dictyocha fibula fibula Ehrenberg, Locker and Martini, 1986, p. 904, pl. 5, figs. 1, 2; pl. 11, figs. 8, 9.
Remarks: For a discussion on D. fibula fibula see McCartney et al. (1995).
Dictyocha mutabilis Deflandre, 1950, pl. 18, figs. 7–14.
Dictyocha brevispina (Lemmermann), Bukry, 1976c, p. 723.
Dictyocha brevispina brevispina (Lemmermann), Bukry, 1978b, p. 816, pl. 2, figs. 9, 10; McCartney et al., 1995, p. 147.
Remarks: For a discussion on D. mutabilis, see McCartney et al., 1995.
Dictyocha hexacantha Schulz, 1928, p. 255, fig. 43; Bukry, 1975b, pl. 4, figs. 1, 2; Ciesielski, 1991, pl. 7, fig. 3 (note: good photograph of inclined specimen).
Remarks: D. hexacantha differs from D. spinosa because the extra spines are mounted on the basal ring rather than the apical structure.
Dictyocha medusa Haeckel, 1887, pl. 101, figs. 13, 14; Perch-Nielsen, 1975, pl. 4, figs. 4, 5; pl. 15, figs. 5–7.
Remarks: Haeckel's (1887) illustration of this taxon shows four struts that meet to form an X intersection without a bridge. Bukry and Foster (1973) and others apply this taxon to silicoflagellate skeletons in the Miocene and Pliocene that have a rhomboid basal ring and a very short to nonexistent apical bridge. Mandra (1968) found a similar morphology in the upper Miocene of Southern California, which he called Dictyocha staurodon, although the type specimen for D. staurodon (Ehrenberg, 1844; see Loeblich et al., 1968, pl. 24, fig. 18) has a very small apical window. These occurrences are typically infrequent, and we believe that they are variants of co-occurring D. fibula or D. extensa (see McCartney et al., 1995, p. 146).
Perch-Nielsen (1975) has applied D. medusa to a group of silicoflagellates that have a quadrate basal ring and short apical bridge. Perch-Nielsen found this taxon to be quite abundant, composing about half the total silicoflagellates in the lower and upper Eocene of DSDP Hole 280A and less abundant at several other sites from Leg 29. She notes that D. medusa is quite variable, with graduations toward D. crux. We find a very similar silicoflagellate in the middle Miocene of Hole 1219A, which we call D. medusa, as applied by Perch-Nielsen. We do not believe this taxon to be the same species as the D. medusa used by Bukry and Foster (1973), which is from the upper Miocene.
Corbisema spinosa Deflandre, 1950, p. 193, figs. 178–182; Glezer, 1966, p. 238, pl. 10, figs. 6–8; McCartney and Wise, 1987, pl. 1, fig. 6; McCartney and Wise, 1990, pl. 2, fig. 2.
Remarks: D. spinosa has three spines on the apical structure. This taxon is found in a short interval from Sample 199-1219A-21H-6, 70–71 cm, to 21H-4, 70–71 cm, and is included here as a subzone of the D. hexacantha Zone. There is a probable evolutionary connection between D. spinosa, D. hexacantha, Dictyocha deflandrei, and Dictyocha frenguellii, but a core sequence in which most or all of these taxa occur that could be used to document the evolutionary relationships has so far not been found. D. spinosa usually appears earlier and disappears later than D. hexacantha (McCartney and Wise, 1987), but, in this study, D. spinosa is observed over a more narrow interval than D. hexacantha.
Dictyocha varia Locker, 1975, pp. 99–101, figs 3–7.
Dictyocha pulchella Bukry, 1975a, p. 687, pl. 4, figs. 1–3.
Dictyocha varia Locker, McCartney et al., 1995, p. 148, pl. 3, fig. 1; pl. 5, fig. 2; pl. 8, fig. 6.
Remarks: Specimens of D. varia were much less abundant in this study than for Leg 138 (McCartney et al., 1995), wherein this taxon was very abundant and predominant.
Distephanus crux Ehrenberg, 1840, p. 207; Ehrenberg, 1854, pl. 18, fig. 56; pl. 33(XV), fig. 9.
Distephanus crux hannai Bukry, 1975b, p. 855, pl. 4, figs. 4–6; see also Bukry, 1975a, pl. 2, figs. 2, 3.
Remarks: D. crux hannai is distinguished by a very small apical ring. The taxon was found in a narrow interval, Sample 199-1219A-6H-4, 70–71 cm, to 6H-1, 70–71 cm (44.7–49.2 mbsf), from the lower Miocene. The specimens found in this study typically had a rhomboid basal ring.
Distephanus crux f. longispinus Schulz, 1928, p. 256, fig. 44.
Distephanus longispinus (Schulz), Bukry and Foster, 1973, p. 828, pl. 4, figs. 7, 8.
Remarks: Only rare specimens of this taxon were found in the middle Miocene of Hole 1219A.
Dictyocha speculum Ehrenberg, 1840; Ehrenberg, 1854, pl. 18, fig. 57; pl. 19, fig. 41; pl. 21, fig. 44; pl. 22, fig. 47.
Distephanus speculum (Ehrenberg), Haeckel, 1887, p. 1565.
Distephanus speculum speculum (Ehrenberg), Bukry and Foster, 1973, p. 828, pl. 5, fig. 8.
Remarks: Multi-windowed skeletons of this taxon were not counted separately, as only five specimens were found and all were found in the upper Oligocene section.
Distephanus stauracanthus (Ehrenberg), Haeckel, 1887, v. 18, p. 1564; Locker and Martini, 1986, p. 907.
Remarks: One specimen of this unusual taxon was found in Sample 199-1219A-2H-7, 70–71 cm (middle Miocene). This occurrence is of similar age to a horizon described by Martini (1972, see also Locker and Martini, 1986) and found in the middle Miocene section of Leg 138 (McCartney et al., 1995).
Dictyocha fibula var. octagona Tsumara, 1963, pl. 2, fig. 4; pl. 10, figs. 11–13; pl. 23, figs. 8–10.
Dictyocha octagona (Tsumara), Martini, 1971, p. 1697, pl. 1, fig. 15.
Distephanus stauracanthus f. octagonus (Tsumara), Locker and Martini, 1986, p. 907, pl. 6, fig. 8.
Remarks: This taxon is distinguished by its eight-sided basal ring which displays eight equant spines. It differs from D. stauracanthus stauracanthus because it has an inclined dictyochid bridge rather than a cruxoid apical ring, characteristic of D. crux.
Dictyocha navicula biapiculata Lemmermann, 1901, p. 258, pl. 10, figs. 14, 15.
Naviculopsis biapiculata (Lemmermann), Bukry, 1978c, p. 787, pl. 3, figs. 9, 10; McCartney and Harwood, 1992, p. 825, pl. 1, figs. 3, 7, 8.
Remarks: This taxon has considerable variability, especially in the width and size of the basal ring and the size of the basal spines. The basal ring is oval to elongate with spine lengths that are less than length of the basal ring. The bridge extends higher in comparison to N. constricta and Naviculopsis eobiapiculata. The apical bridge width is usually ~5 µm with a gradual increase toward the basal ring. Some specimens (see Pl. P1, fig. 5) possess a portal in the expanded area where the bridge attaches to the basal ring.
Transitional specimens between N. constricta and N. lata were also found. Multiple specimens were found to have windows within the bridge near the basal ring as illustrated by Bukry (1980b, p. 565, pl. 5, fig. 11). Bukry called these "Dictyocha sp. (naviculopsoid)," but we consider them as a variation within the Naviculopsis species. Also, Bachmann (1970, p. 295, pl. 2, figs. 6–8, 11, 13) illustrates windows within variations of N. lata that are very similar to the specimens of N. biapiculata, illustrated in this study. Ciesielski (1991, p. 96, pl. 10, figs. 8, 9) has two very similar figures of the windowed varieties of N. biapiculata.
Bukry (1978a) provides a drawing showing the proportional difference between N. biapiculata, N. lata, and Naviculopsis quadrata.
Dictyocha navicula biapiculata constricta Schulz, 1928, p. 246, fig. 21.
Naviculopsis constricta (Schulz), Bukry, 1975b, p. 856, pl. 7, figs. 1, 2; McCartney and Wise, 1987, p. 807, pl. 5, figs. 1, 2.
Remarks: N. constricta is characterized by an elongate basal ring with sides that are parallel but slightly constricted at the apical bridge. The basal spines are half the length of the basal ring maximum or longer. The width of the apical bridge varies considerably among our specimens. N. constricta was differentiated from N. foliacea in having windows that were longer than the width of the bridge.
Specimens of N. constricta were very abundant in Sample 199-1219A-14H-6, 70–71 cm (128.2 mbsf), with some skeletons having a narrow basal ring with very long basal spines.
Naviculopsis foliacea Deflandre, 1950, p. 204, figs. 235–240; McCartney and Wise, 1987, p. 807, pl. 5, figs. 3, 4; see also p. 807, fig. 2.
Remarks: N. foliacea is typified by an apical bridge that has a width of two-thirds or more of the interior length of the basal ring. N. foliacea was very abundant in Sample 199-1219A-14H-6, 70–71 cm (128.2 mbsf), but otherwise was very rare.
A single specimen of this taxon in Sample 199-1219A-4H-7, 70–71 cm (34.5 mbsf), is interpreted as reworked.
Naviculopsis lacrima Bukry, 1982, p. 443, pl. 7, figs. 1–10.
Remarks: Two unusual specimens that we identify as N. lacrima were observed in Sample 199-1219A-14H-6, 70–71 cm (128.2 mbsf). The shape of these skeletons is very similar to what Bukry (1982) described and illustrated, although the bridge is connected to the basal ring by struts that create a window on each side. The basal ring is elongate (90 µm), slender (15 µm), and biconvex. The spines are ~20 µm, and the length of the basal ring is 45 µm.
Dictyocha biapiculata lata Deflandre, 1932, p. 500, figs. 30, 31.
Naviculopsis lata (Deflandre), Ling, 1972 (in part), p. 185, pl. 30, figs. 12–14; Bukry, 1975b, p. 856, pl. 7, fig. 4.
Remarks: Like N. biapiculata (see "Naviculopsis biapiculata
[Lemmermann]"), N. lata was found to have considerable variability, with the shape of the basal ring ranging from elongate to circular. Bukry (1978a, p. 698, fig. 3) proposed morphometric criteria to assist in distinguishing N. lata, N. biapiculata, and N. quadrata. He suggested that N. lata has a spine length less than half the length of the basal ring. We used this criterion for separating the species, but there were transitional forms in which the separation was difficult. We did not observe specimens with the sharply angled corners typical of N. quadrata.
Dictyocha ponticulus Ehrenberg, 1844, pp. 258, 267; Bailey, 1845, pl. 4, fig. 21.
Naviculopsis ponticula (Ehrenberg), Bukry, 1978b, p. 821, pl. 8, figs. 9, 10.
Naviculopsis obtuscarca Bukry, 1978b, p. 821; type specimen in Bukry, 1978a, p. 709, pl. 3, fig. 4.
Naviculopsis ponticula ponticula Bukry, 1982, p. 431, pl. 8, figs. 11, 12; pl. 9, fig. 1.
Naviculopsis ponticula spinosa Bukry, 1982, p. 434, pl. 9, figs. 2–6.
Remarks: There is considerable variation in this group, which Bukry (1978b, 1982) has subdivided into several taxa. In the Hole 1219A assemblages, we observe most of the range of variation listed in the synonymy but were unable to consistently divide into the taxa described by Bukry (1982). This variation, also discussed by McCartney and Wise (1990), occurs on the axial end of the basal ring. There is typically a flattened termination of the axial end of the basal ring, although some specimens with a round axial end (see Bukry, 1982, pl. 9, fig. 6) were counted as N. ponticula because of the presence of a spine. The counts for N. ponticula also include some skeletons that are similar to Naviculopsis contraria (Bukry, 1982, p. 442, pl. 6, figs. 5–13), but we believe these morphologies to be part of the range of variation for N. ponticula.
Specimens that appeared to be transitional between N. ponticula and Naviculopsis navicula were found in Sample 199-1219A-4H-4, 70–71 cm (30.2 mbsf). N. navicula has an elongate basal ring with a rounded termination of the long-axis ends, without a spine, although Bukry (1976a) states that rare specimens with spines do occur. Bukry (1982) shows that this morphology occurs at the bottom of the N. ponticula Zone, suggesting that N. navicula has some biostratigraphic value and may be the evolutionary ancestor of N. ponticula.
Naviculopsids of similar shape, with large basal ring and long spines, have been illustrated in the early DSDP literature (e.g., Bukry and Foster, 1973, pl. 3, figs. 6, 7) but are here believed to be Neonaviculopsis neonautica (Locker and Martini, 1986). Neonaviculopsis was found by McCartney et al. (1995) in the upper Miocene section of Hole 850B, which is of similar age to the occurrence documented by Bukry and Foster.
Diagnosis: Elongate, asymmetrical basal ring with two major spines and a minor spine on one side of the ring, surmounted by a wide Y-shaped apical bridge.
Description: Naviculopsis trigeminus has an elongate basal ring typical of Naviculopsis, with both major axis spines and one minor axis spine positioned at the midpoint along one side of the specimen. The major-axis spines are unusually wide where they attach to the end of the basal ring and sometimes appear to be flattened. The minor-axis spine is much smaller. The side with the minor-axis spine is more representative of the genus Dictyocha than Naviculopsis, in having two struts with a portal. From an abapical view, there are pikes directly beneath the strut attachments on the "Dictyocha" side of the specimen but not on the side that lacks struts. The struts support a wide flattened bridge that has the shape of a triangular plate. The portal between the struts is typically small. The side without the struts and spine is elongate and usually has a constriction at the connection to the bridge similar to that of N. constricta.
Remarks: Sixteen specimens were found in two microscope slides. This number and similarity among the specimens preclude the possibility that this unusual morphology is teratoid. There were no intermediates between N. trigeminus and N. constricta found in Sample 199-1219A-23H-5, 70–71 cm (212.2 mbsf), in the middle Eocene.
N. trigeminus is distinguished from Dictyocha elongata Glezer (1966; see also Bukry, 1978b, pl. 1, fig. 18; pl. 2, figs. 1–3, from the late Paleocene) by a wider apical apparatus and a narrower minor-axis width. Most of the D. elongata specimens illustrated by Bukry (1978b) have three much more equal sized sides and spines, although the specimen illustrated by Bukry (1978b, pl. 2, fig. 3) is generally similar to N. trigeminus but lacks the larger apical plate and flattened basal major-axis spines. Naviculopsis danica (Perch-Nielsen, 1976; see also Bukry, 1978b, pl. 3, fig. 15) has a morphology similar to N. trigeminus but has a narrow bridge with three or four narrow struts, longer major-axis spines, and no third spine. Both D. elongata and N. danica are found in the upper Paleocene, which could suggest possible ecophenotypic or evolutionary relationships.
Perch-Nielson (1976) described two unusual Naviculopsis from the D. hexacantha Zone. Naviculopsis punctilia (see also Bukry, 1976b, pl. 2, fig. 3) is strutted on both sides but has much longer and narrower basal spines and commonly lacks minor-axis spines, although some specimens do have small minor-axis spines. N. punctilia also has a bar extending across the width of the skeleton rather than the wide triangular plate typical of N. trigeminus. Naviculopsis vemae has extraordinary variability, both in the shape of the basal ring and the apical bridge, although the struts are typically not at the midpoint of the basal ring and do not have the plate found on N. trigeminus. N. punctilia and N. vemae appear more closely related to one another than either specimen is to N. trigeminus.
Martini (1976) described an ebridian, Micromarsupium rostovense from the lower Oligocene of the Rostov area of Russia, that has a general configuration similar to N. trigeminus. The ebridian is elongate with two attaching struts on one side that are close together and form a small portal and a longer strut that attaches to the other side of the ring. The ebridian, however, does not have spines of any type and the "apical structure" is not centered between the two ends of the ring. There are other obvious differences, but the general similarities are interesting.
Occurrence: N. trigeminus is found in the middle Eocene in the equatorial Pacific Ocean.
Size: Most of the observed specimens were measured. The length between the tips of the two major spines ranged from 36 to 50 µm and from 12 to 22 µm across the width of the basal ring including the minor spine. The length of the portal opening between the two struts was 4–8 µm. The holotype has a major-axis length of 44 µm and a minor-axis length of 18 µm.
Holotype: Plate P1, fig. 7.
Repository: The microscope slide containing the holotype is located at the California Academy of Sciences (CAS) Diatom Collection, slide CAS #221085.
Type Locality: Equatorial Pacific Ocean, Sample 199-1219A-23H-5, 70–71 cm.
Dictyocha navicula trispinosa Schulz, 1928, p. 246, fig. 23a, 23b.
Naviculopsis trispinosa (Schulz), Glezer, 1966, v. 7, p. 277, pl. 17, fig. 7; Bukry, 1975b, p. 857, pl. 7, figs. 5–7.
Remarks: The two specimens assigned to N. trispinosa in this study are closely similar to N. biapiculata but possess a long apical spine of a length approximately similar to the basal spine lengths. Excellent photographs of this unusual species can be found in Perch-Nielsen (1976, pl. 13). McCartney and Wise (1990) noted a possible correlation between the presence of this taxon and five-sided Distephanus, but no similar correlation was found in this study.