Glyptograptus fastigatus (Haberfelner, 1931)

Glyptograptus fastigatus (Haberfelner, 1931)

Figures 8C–D View FIGURE 8 ; 9C, F View FIGURE 9

1931 Glyptograptus tamariscus mut. fastigatus nov. mut.; Haberfelner, pp. 105–106, pl. 3, Figs. 17a–e.

1962 Glyptograptus sp. cf. G. tamariscus fastigans Haberfelner ; Packham, pp. 512– 513, pl. 71, fig. 5, text–fig. 3f.

1970 Glyptograptus aff. G. tamariscus fastigans Haberfelner, 1931 ; Hutt, Rickards, and Skevington, p. 6, pl. 1, fig. 14.

1979 Diplograptus (Orthograptus) ultimus Manck ; Jaeger and Robardet, pl. 2, figs. 1, 20.

1989 Glyptograptus aff. G. fastigans Haberfelner ; Melchin, p. 1740, fig. 11D (non B).

1991a G. fastigatus Haberfelner 1931 ; Loydell, p. 242, fig. 8c.

1992 Glyptograptus fastigatus Haberfelner, 1931a ; Loydell, p. 30–31, pl. 1, figs. 4–5, text-fig. 11, figs. 2, 4, 22.

2015 Glyptograptus fastigatus Haberfelner ; Loydell, Frýda, and Gutiérrez-Marco, figs. 16V, AA, 18B–D, 20K.

Holotype. Not assigned yet. Type collection of Gl.

fastigatus described by Haberfelner (1931, pp.

105-106, pl. 3, Figs 17a–e) came from the turriculatus Biozone sensu lato of Hochwipfel in the Car-

nic Alps, Austria.

Material. 34 flattened, mostly complete tubaria

Description. The present, mostly immature tubaria have a pronounced wedge shape, usually 6.7–7.5

mm long, but one specimen attained a length of 28

mm. There is a sicula visible only in reverse view without an apex, and its length is 0.8–0.9 mm. The apex reaches the level of the middle of the second thecae, and the aperture width varies between

0.22–0.25 mm. A virgella has not been observed.

The tubarium is only 0.5 mm wide at the first thecal pair, but then it widens significantly to 0.8–0.9 mm

at th3, and 1.2–1.4 mm at th5. In some specimens having more than 10 thecal pairs, the width at th10

varies between 1.9 and 2.0 mm. The length of th 11

varies between 0.6–0.7 mm, and th 12 crosses the ventral wall of the sicula approximately 0.5 mm

above the sicular aperture. Subsequent thecae are relatively long, regularly alternating in the proximal part. Towards the distal part of the tubarium, thecae become wider and form only a gentle sigmoidal curve, with very shallow apertural excavations. Thecal overlap varies between onethird and one-quarter of the thecal length. Thecal apertures, 0.15–0.21 mm wide, are perpendicular to the axis of the tubarium. Thecae are loosely spaced relative to the tubarium width, with 2TRD 2 1.7–2.13 mm, and 2TRD 5 1.9–2.1 mm. The nema fine, observed in four specimens, is little projected distally beyond the thecate part. The tubarium of a presumably circular or nearly circular cross section is commonly flattened in scalariform or sub-scalariform orientation.

Remarks. Almost all measured parameters correspond with descriptions of Gl. fastigatus provided by Packham (1962) and Loydell (1992). The only exception is the tubarium width, where the measured values in the distal part of the tubarium correspond to Glyptograptus auritus (Bjereskov, 1975) . The 2TRD is generally lower than that reported for Glyptograptus fastigatus (2TRD2 1.55–2.15 mm; 2TRD5 2.00– 2.25 mm) but, on the contrary, it is higher than 2TRD reported for Glyptograptus auritus (1.65 mm for 2TRD 2 and 1.9 mm for 2TRD 5) by Loydell (1992). Glyptograptus fastigatus was first described by Haberfelner (1931), who documented its occurrence from the maximus Subzone, which corresponds (according to Loydell 1992) in about the lower-middle guerichi Biozone. Haberfelner also mentioned the possibility of very limited stratigraphic occurrence within one biozone. His assumption was confirmed by Packham (1962), Melchin (1989), Loydell (1992), and Loydell et al. (2015), all of whom found this species in similar stratigraphic levels. Its present record in Bohemia (Prague Synform) in the linnaei Biozone is in accordance with previous findings. When comparing the descriptions of Glyptograptus fastigatus (Haberfelner, 1931) and Glyptograptus auritus ( Bjerreskov, 1975) in detail, a considerable similarity was found. It should be stressed, however, that a basal disc developed in mature specimens of G. auritus has not been recorded in our material. In addition, the species Glyptograptus auritus , defined by Bjerreskov (1975), was documented from the lower part of her turriculatus Biozone. However , from the detailed notes of the work and associated graptolite fauna, it follows that this lower part also corresponds to the guerichi Biozone. It would be appropriate to subject the two species to a thorough revision in the future regarding the possible role of intraspecific variability. For example, in the genus Parapetalolithus (defined by Koren’ and Rickards, 1996), P. palmeus , and P. elongatus were distinguished as separate subspecies (and later species) for several decades (variants of P. p. palmeus , P. p. clavatus, P. e. elongatus , and P. e. linearis). The reason was the significantly expanded (even bulging) proximal part of the tubarium and thus increased DVW (dorsoventral-width) values. However, according to the works of Loydell (1992), Štorch (1998a) and the most recent systematic revision by Strossová (2024), it is still two species, not four.