Trocholites remelei Schröder, 1891

Trocholites remelei Schröder, 1891

Fig. 16 View Fig ; Table 7 View Table 7

Trocholites Remeléi Schröder, 1891: 18 View in CoL (156).

Trocholites remeléi – Neben & Krueger 1971: pl. 32 figs 4–5.

non Trocholites incongruus – Angelin 1880: 11, pl. 9 figs 15–18.

non Trocholites remeléi – Neben & Krueger 1971: pl. 32 figs 1–3.

Diagnosis

Species of the genus Trocholites with conch at dm 22 mm thinly pachyconic (CWI ~ 0.60) and subevolute (UWI ~ 0.30). Whorl profile weakly depressed (WWI ~ 1.43) and moderately impressed (IZR ~ 0.34), rounded from lateral sides and slightly flattened from ventral side. Coiling rate is moderate (WER ~ 1.88). Shell ornament with low, regularly spaced clusters of raised lirae manifested on internal mould as annular ridges.

Type material

Lectotype

SWEDEN – Öland • 1 spec.; Lerkaka ; Lasnamägi or Uhaku regional stages ; 1881; Dames Coll.; illustrated by Neben & Krueger (1971: pl. 32 figs 4–5), re-illustrated here in Fig. 16 View Fig ; MB.C. 11562 .

Description

Lectotype MB.C.11562 ( Fig. 16 View Fig ) is a conch with 22 mm diameter. At least three whorls are visible; the last half whorl belongs to the body chamber. In the last half volution, the conch becomes slightly more slender ( CWI decreases from 0.63 to 0.59) and remains subevolute ( UWI ~ 0.32) with a moderate coiling rate ( WER = 1.88). The body chamber is moderately embracing the preceding whorl ( IZR = 0.34) and less depressed ( WWI decreases from 1.61 to 1.43). The shell is ornamented with low, regularly spaced clusters of raised lirae, which are visible on the internal mould as annular ridges; the lirae extend with a sinus across the venter.

Remarks

Angelin (1880: pl. 9 figs 15–18) illustrated two specimens of Trocholites incongruus from Darriwilian strata of Sweden. Remelé (1880) stated that these specimens do not belong to T. incongruus and subsequently Schröder (1891) established the new species Trocholites remelei based on these specimens. Schröder also assigned a small late Darriwilian trocholitid (MB.C.11562; Fig. 16 View Fig ) from the Island of Öland ( Sweden) to T. remelei . This was illustrated by Neben & Krueger (1971) and is chosen here as lectotype. Examination of the two specimens NRM Mo 152355 and NRM Mo 152354 of Angelin (1880) revealed that they are more discoidal (CWI = 0.50 and 0.41 vs 0.59), with a wider umbilicus and less impressed whorls. They possess a different type of ornament than the lectotype and each is assigned to a different species below ( Trocholites tureki sp. nov. and T. freyjae sp. nov.).

It has to be noted that Neben & Krueger (1971) also included syntype MB.C.11555.2 of T. hospes (Remelé 1890: pl. 2 fig. 4) in T. remelei ; however, this is not accepted here since no annular ornament elements are present on the shell surface or internal mould surface of this specimen ( Fig. 8D View Fig ).

Lectotype MB.C.11562 is unique among specimens of Trocholites because of the relatively stout conch ( Fig. 12C View Fig ) combined with narrow umbilicus and prominent annuli that are visible on the shell surface as well as on internal mould.