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Species Hoploscaphites pungens Binkhorst 1861 | ||||||
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| Discussion / Comments: | ||||||
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Machalski (2005): TYPE MATERIAL.- Holotype, by monotypy, is MNB C606a, b, a micro− conch, the original of Binkhorst (1861: pl. 5a3: 1a–d), refigured by Ken− nedy (1987: pl. 35: 1–3), from the lower upper Maastrichtian Kunrade Limestone facies of the Maastricht Formation at Kunrade, the Nether− lands. MATERIAL.- From Belgium: five specimens from CBR− Romontbos quarry (NHMM 1992062–1992066). From the Netherlands: a single specimen from Kunrade (NHMM 003529) and a silicone cast of a single specimen from the ENCI quarry (NHMM JJ 11883). DISCUSSION.- Topotypical material of Hoploscaphites pun− gens as described by Kennedy (1987) comes from the upper portion of the Kunrade Limestone facies of the Maastricht Formation (Kennedy 1987; Jagt and Kuypers 1994) as for− merly exposed in the Kunrade−Benzenrade area (the Nether− lands). Most of these specimens are adultmicroconchs charac− terised by a low whorl to the body chamber, trapezoid whorl section, blunt ribs and prominent tuberculation. The tuber− culation of the phragmocone consists of lateral tubercles (in− ner ventrolateral tubercles of Kennedy 1987) and much stron− ger ventrolateral ones (outer ventrolateral tubercles of Ken− nedy 1987). The lateral tubercles do not extend onto the body chamber while the ventrolaterals do, but never reach the hook. Quite strong ventral swellings are observed on the body cham− bers of some specimens, including the holotype. Kennedy (1987) thought H. pungens to be endemic to the Kunrade area. However, subsequent studies have demon− strated this species to occur in the Gronsveld (Jagt and Kuypers 1994), Nekum and basal Meerssen members (van der Tuuk 1987; Jagt 1995, 2002) of the Maastricht Forma− tion. Hoploscaphites pungens has never been reported from outside the Maastricht area. However, Discoscaphites acuti− tuberculatus Tzankov, 1982 from the upper Maastrichtian of Drandar near Varna, Bulgaria, based on tuberculate spires, seems to be closely related, if not conspecific. One of the specimens figured by Tzankov (1982: pl. 7: 10) appears closely similar to a spire of H. pungens studied herein (NHMM 1992063) from the upper Nekum Member at the CBR−Romontbos quarry (Jagt 1995: pl. 5: 9, 10). A direct study of the originals from Bulgaria is needed to clarify the taxonomic position of D. acutituberculatus. Adult microconchs from the upper Maastrichtian Severn Formation ofMaryland, identified as Jeletzkytes nebrascensis (Owen, 1852) by Landman and Waage (1993a: fig. 133A–C) and Kennedy et al. (1997: pl. 22: A–C, pl. 23: D, E) are similar to H. pungens, although associated macroconchs (e.g., Land− man and Waage 1993a: pl. 133 D) morphologically resemble typical specimens of J. nebrascensis as recorded from the U. S. Western Interior (Landman and Waage 1993a). Kennedy (1987) was unable to separate his material into macro− and microconchs. According to Jagt (1995: 32), spec− imens studied by Kennedy represented microconchs, “as they lack an umbilical bulge and body chambers are not markedly inflated”. This view is supported here, except for a single specimen (Kennedy 1987: pl. 34: 10, 11) here re− garded to be a macroconch as based on the proportions of the preserved part of the body chamber. Specimens illustrated by Jagt and Kuypers (1994: fig. 3a, b) and Jagt (1995: pl. 5: 5–7) are considered macroconchs for the same reason. Amongst the specimens studied, NHMM JJ 11883 from the basal metre of the Nekum Member (Maastricht Formation) is also an adult macroconch c. 85 mm in maximum di− ameter. Specimen NHMM 1992066 (Jagt 1995: pl. 5: 14) is clearly a microconch. Specimens NHMM 1992063 (Jagt 1995: pl. 5: 9, 10) and NHMM 1992064 (Jagt 1995: pl. 5: 11, 12; Fig. 14B) are too fragmentary to be identified in terms of dimorphism. Allmacroconchs share the same style of tuberculation with microconchs of H. pungens (Fig. 17A, B) and are held to be conspecific. NHMM JJ 11883 (Figs. 14D, 17B) is the best− preserved adultmacroconch known to date. The phragmocone tuberculation consists of four rows; the outermost position is taken by strong ventrolateral tubercles, followed by outer lat− eral ones, which are less pronounced than the ventrolaterals. The next row is formed by incipient, swollen inner laterals, followed by umbilical bullae. Only fine ventrolaterals and massive umbilical bullae/tubercles are visible on the preserved part of the body chamber. The ribbing of the phragmocone consists of robust and straight primaries, closely resembling those of microconchs (compare Fig. 17A, B) and secondaries, which are more densely spaced than the primaries and origi− nate at the line of the outer lateral tubercles. The preserved part of the body chamber is covered by delicate primaries and secondaries of various lengths. The largest specimen of H. pungens seen is NHMM 003529 (Kennedy 1987: pl. 35: 10, 11), a fragment of a body chamber with a low whorl, thus almost certainly a micro− conch. The specimen is too fragmentary to be adequately measured. However, it appears larger than the largest macro− conch (NHMM JJ 11883). The only other scaphitid species with a similar size relationship between macro− and micro− conchs is Hoploscaphites pumilus (Stephenson, 1941) from the Campanian/Maastrichtian boundary interval of the United States (Kennedy and Cobban 1993) and Europe (Kennedy et al. 1986; Machalski and Odin 2001). The largest microconchs of this species, defined by the concave umbili− cal wall of the shaft, are larger than the largest known macroconchs, defined by the presence of an umbilical bulge (Machalski and Odin 2001: 491). Kennedy (1987) considered H. pungens to be a short− lived offshoot of the H. constrictus lineage. He stressed its overall similarity to H. schmidi (Birkelund, 1982), also based on a microconch (see below), but stated that the latter species “never develops the inner ventrolateral tubercles of pungens [lateral tubercles in the present paper] and has a very feebly ribbed final section of the body chamber. The siphonal and outer ventrolateral tubercles are also much stronger in pun− gens” (Kennedy 1987: 203). This is not entirely true as a row of incipient lateral tubercles does occur in the phragmocone of the holotype of H. schmidi (Figs. 16A1, 17C). Macro− conchs of H. pungens and H. schmidi show an even closer similarity, the only significant difference being the presence of an additional row of lateral tubercles on the phragmocone and a coarser ribbing of the hook in the former (compare Fig. 17B and D). Cooper (1994) united H. pungens and H. schmidi in a new subgenus, Hoploscaphites (Tovebirkelundites), defined on the basis of conspicuous siphonal swellings on the body chamber (Cooper 1994: 184). However, Kennedy and Jagt (1998) pointed out the presence of siphonal swellings in Hoploscaphites constrictus and concluded Tovebirke− lundites to be a junior synonym of Hoploscaphites sensu stricto. STRATIGRAPHIC AND GEOGRAPHIC RANGE.- Lower upper Maas− trichtian in the Netherlands and Belgium (Belemnitella ju− nior Zone of authors) and, possibly, upper Maastrichtian of Bulgaria. |
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| Systematics: | ||||||
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51 Familia Scaphitidae Genus Hoploscaphites Species Hoploscaphites schmidi |
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| Synonym list: | ||||||
| Machalski (2005): 1861 Ammonites n sp. pungens Binkhorst. - Binkhorst : p.32 pl. 5a3: fig. 1a-d
? 1982 Discoscaphites n sp. acutituberculatus Tzankov. - Tzankov : p.25 pl. 7; fig. 9, 10
1987 Hoploscaphites pungens Binkhorst. - Kennedy : p.202 pl. 23, fig. 3,4;
pl. 32, fig. 22-25;
pl. 34, fig. 2-6, 10, 11, 18, 19;
pl. 35, fig. 1-11
1987 Hoploscaphites pungens Binkhorst. - Tuuk : p.62 fig. 12, 18a-c [van Binckhorst [sic] 1861]
1994 Hoploscaphites pungens Binkhorst. - Jagt & Kuypers : fig. 3a, b [Binckhorst [sic], 1861]
1995 Hoploscaphites pungens Binkhorst. - Jagt : p.31 pl. 5; fig. 5-14
p 1998 Hoploscaphites sp. . - Kennedy & Jagt : p.163 pl. 2; fig. 10, 11 [non pl. 2; fig. 12-15 = H. sp. ex gr.
waagei-angmartus-sutensis]
2005 Hoploscaphites pungens Binkhorst. - Machalski : p. 675, 678 fig. 14B, D, 17A, B
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| Stratigraphy - relative ages: | ||||||
| upper Maastrichtian: Machalski (2005) |
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| References: | ||||||
Binkhorst,J.T.. (1861): Tzankov,V.. (1982): Kennedy,W.J.. (1987): Tuuk,V.V.L.. (1987): Jagt,J.W.M.. and Kuypers,M.M.M.. (1994): Jagt,J.W.M.. (1995): Kennedy,W.J.. and Jagt,J.W.M.. (1998): Machalski,M.. (2005): |
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| Anonymous: Unedited TaxonConcept data | ||||||
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