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Isfarispira septata
Taxonomy
Isfarispira septata was named by Gubanov et al. (1995). Its type locality is PI-5, Pschemack Mountains, east of Isfara River, which is in a Wenlock carbonate siltstone/limestone in the Chorkuin Formation of Tajikistan. It is the type species of Isfarispira.
It was recombined as Pycnomphalus septata by Wagner (1999), Wagner (1999).
It was recombined as Pycnomphalus septata by Wagner (1999), Wagner (1999).
Synonymy list
| Year | Name and author |
|---|---|
| 1995 | Isfarispira septata Gubanov et al. pp. 835 - 838 figs. txt. f. 2; pl. 1 |
| 1999 | Pycnomphalus septata Wagner |
| 2018 | Isfarispira septata Peel |
| 2023 | Isfarispira septata Wagner p. S3352 |
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If no rank is listed, the taxon is considered an unranked clade in modern classifications. Ranks may be repeated or presented in the wrong order because authors working on different parts of the classification may disagree about how to rank taxa.
†Isfarispira septata Gubanov et al. 1995
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Diagnosis
| Reference | Diagnosis | |
|---|---|---|
| A. P. Gubanov et al. 1995 | At least ten whorls are present. The large lenticular shell is divided into upper and lower surfaces by the prominent peripheral angulation; the shell height varies from three-eighths to about half of the diameter.
Sutural indentation is very slight. The sides of the low spire vary from slightly convex, such that the shell is weakly cyrtoconoid, to almost flat, but become shallowly concave in the latest growth stage because of an increase in the shell width at the transition to the final whorl. Early growth stages are poorly known. The width of the whorl in cross section, measured perpendicular to the axis of coiling, is about twice the height. The lower (basal) and upper (parietal) walls become increasingly parallel with growth of the shell, such that the two surfaces are both perpendicular to the axis of coiling in the umbilical region in the latest growth stage, but curve slightly adapically as the angular periphery is approached; the base is shallowly convex. The outer whorl surface is very shallowly convex between the periphery and the suture with the previous whorl, more so in early whorls. The final whorl is more noticeably flattened. The umbilical wall is sub-parallel to the axis of coiling and passes angularly into the lower and upper whorl surfaces. The aperture is radial. Poorly preserved growth lines on the base of the holotype are shallowly convex adaperturally. In the same specimen, very poorly preserved growth lines on the outer whorl surface near the aperture are very slightly concave (adaperturally) as they traverse the outer whorl surface, with adapical obliquity, towards the periphery. Thus, there is a very shallow peripheral sinus, but there is no evidence to suggest the presence of a slit and selenizone. The umbilicus is seen to be wide in cross section but it is closed by a blade-like circumbilical flange which extends from the umbilical shoulder, as a continuation of the base, into the umbilicus. In some specimens, this flange extends across the umbilicus towards the umbilical suture a half whorl previously. In other specimens, the flange curves with increasing convexity towards the axial region. The flange is apparently narrower in the immediate vicinity of the aperture, with a thickened termination, but seems to attain its full extent within a whorl back from the apertural margin. The shell interior is traversed by abundant septa which are concave adaperturally. In the holotype the body chamber seems to extend over at least one and three-quarter whorls. Adapical of this point, a number of septa are visible but they appear to be irregularly spaced. In cross section, septa are usually visible near the whorl periphery as adaxially concave surfaces which are less angular than the adjacent whorl periphery. The coalescence of septa in the area of the periphery and suture produces a thickening of the shell which gives some internal moulds a slightly gradate profile. The shell itself is seemingly quite thin, relative to the large size of the gastropod, but the flange and umbilical wall appear to be thickened at the aperture in the holotype. |
Measurements
No measurements are available
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| Source: f = family, c = class | |||||
| References: Kiessling 2004, Bandel et al. 2002 | |||||