Cathymorula exilissima, Harzhauser & Landau & Merle, 2025

Harzhauser, Mathias, Landau, Bernard M. & Merle, Didier, 2025, The Muricidae (Gastropoda, Muricoidea) of the Miocene Paratethys Sea (Aspellinae, Ergalataxinae, Coralliophilinae, Rapaninae), Zootaxa 5611 (1), pp. 1-106 : 48-49

Cathymorula exilissima sp. nov.

Figs 26 , 28A–D

Purpura exilis Partsch —Hörnes 1852: 169 (pars) [non Cathymorula exilis (Hörnes, 1852) ].

Purpura (Stramonita) exilis Partsch —Hoernes & Auinger 1882: 152 (pars) [non Cathymorula exilis (Hörnes, 1852) ].

Thais (Stramonita) exilis (Partsch in Hörnes)— Bałuk 2006: 208, pl. 12, figs. 3, 5 [non Cathymorula exilis (Hörnes, 1852) ].

Type material. Holotype: NHMW 1857/0019/0079a, SL: 28.3 mm, MD: 19.2 mm, Grund ( Austria), figs. 28A 1 – A 3 . Paratypes: NHMW 1857/0019/0079b, SL: 29.5 mm, MD: 18.7 mm, Grund ( Austria) , figs. 28B 1 –B 3. NHMW 1855/0002/0007a, SL: 27.4 mm, MD: 17.9 mm, Grund ( Austria), figs. 28C 1 –C 3. NHMW 1855/0002/0007b, SL: 27.8 mm, MD: 20.5 mm, Grund ( Austria), figs. 28D 1 –D 3. Additional paratypes: 3 spec., NHMW 1864/0001/0470, Grund ( Austria) .

Type locality. Grund ( Austria), North Alpine-Carpathian Foredeep .

Type stratum. Silt and clay of the Grund Formation.

Age. Middle Miocene, early Badenian (Langhian).

Etymology. exilissima , referring to Cathymorula exilis (Hörnes, 1852) .

Diagnosis. Medium-sized, solid, globose-ovate shell with high last whorl; spiral sculpture of broad, flattened cords separated by narrow grooves; outer lip with weak ID and five prominent (D1 split, D2–D4 simple), short lirae; columella with weak to subobsolete columellar fold.

Description. Medium-sized, solid, globose-ovate shell with low, coeloconoid spire; apical angle ~80°. Protoconch unknown. Teleoconch of up to four whorls. Suture linear, superficial. Early teleoconch whorls weakly convex to straight sided with periphery (= P1) at abapical suture. Axial sculpture of broad, subobsolete ribs overrun by broad subsutural cord and slightly narrower cords separated by narrow grooves. Last whorl attaining 86–90% of total height; inflated, with convex periphery; rarely with faint shoulder; slowly contracting. No axial sculpture; spiral sculpture of numerous broad, flat cords separated by narrow grooves. Sutural ramp: SP, adis, IP, adis narrow; convex part of whorl: P1–P5 broad, split by shallower grooves; s1–s4 corresponding in width to split part of primary cords; siphonal canal; s5, P6, ADP. Fasciole broad, twisted, delimiting broad, shallow pseudoumbilicus. Aperture ovate, moderately wide. Outer lip not thickened, with blunt ID and five short (D1 bifid, D2–D4 simple), prominent lirae placed some distance within peristome. Anal canal distinctly incised, relatively narrow, accentuated by weak parietal callus. Siphonal canal short, straight, wide, open, deeply notched. Columella broadly excavated with weak to subobsolete columellar fold, occasionally with denticle below, angled at transition to siphonal canal. Columellar callus thin, broad, poorly delimited from base.

Discussion. Cathymorula exilissima sp. nov. was confused by Hörnes (1852) with Cathymorula exilis (Hörnes, 1852) but differs from that species by its convex periphery, which lacks a shoulder and by the absence of any tubercles. In addition, the last whorl of Cathymorula exilissima is much higher and the spire low and largely covered by the last whorl, even more inflated and has five (D1 bifid) instead of four denticles (D1 simple) inside the apertural lip.

Cathymorula exilissima sp. nov. belongs to a Miocene radiation, which is represented in the Proto-Mediterranean Sea by several species, which all have globose-ovate shells with reduced spiral sculpture. Of these, Cathymorula rarisulcata ( Bellardi, 1882) , from the Tortonian of Stazzano ( Italy), is extraordinarily similar to C. exilissima but develops only D1 (simple) to D4 prominent lirae (see Bellardi 1882: pl. 11, fig. 13; Ferrero Mortara et al. 1981: pl. 32, fig. 9). Cathymorula reflexa ( Bellardi, 1882) , from the Burdigalian of Valle Ceppi ( Italy), differs from C. exilissima in its higher spire and more elongate ovate outline (see Bellardi 1882: pl. 11, fig. 5; Ferrero Mortara et al. 1981: pl. 32, fig. 3). The same features distinguish Cathymorula arata ( Bellardi, 1882) , from the Early or Middle Miocene of the Colli Torinesi ( Italy) (see Bellardi 1882: pl. 11, fig. 10; Ferrero Mortara et al. 1981: pl. 32, fig. 4). Cathymorula erosa ( Bellardi, 1882) , from the Tortonian of S. Agata ( Italy), has a dome-shaped spire, a straight columella, weaker spiral sculpture and lacks denticles in the outer lip (see Bellardi 1882: pl. 11, fig. 12; Ferrero Mortara et al. 1981: pl. 32, fig. 8). Purpura erosa and Purpura rarisulcata were not included in the genus Cathymorula by Landau et al. (2007: 53) due to the poor preservation of the shells. However, they are likely to belong there.

Paleoenvironment. Shallow marine, inner neritic. At the locality Grund fossiliferous channel fills, which formed in middle to outer neritic environments bear allochthonous assemblages uniting coastal-mudflat faunas with inner neritic ones (Zuschin et al. 2005).

Distribution in Central Paratethys. Badenian (Middle Miocene): Korytnica Basin: Korytnica ( Bałuk 1995); North Alpine-Carpathian Foreland Basin: Grund ( Austria) (Hoernes & Auinger 1882).

Genus Ergalatax Iredale, 1931

Type species. Ergalatax recurrens Iredale, 1931 [= Ergalatax pauper (Watson, 1883) ; original designation by Iredale (1931: 231). Present-day, Australia.

Discussion. MolluscaBase eds (2024d) lists nine extant species of Ergalatax . Only two species are known from the European Neogene: Ergalatax seraphinae ( Boettger, 1902) from the Middle Miocene of the Central Paratethys and Ergalatax cf. seraphinae sensu Lozouet et al. (2001) from the Early Miocene of the northeastern Atlantic.

Figures

FIGURE 26. Cord diagrams and apertural features of Ergalataxinae.

FIGURE 28. Cathymorula exilissima sp. nov. A1–A3. holotype, NHMW 1857/0019/0079a, Grund (Austria). B1–B3. paratype, NHMW 1857/0019/0079b, Grund (Austria). C1–C3. paratype, NHMW 1855/0002/0007a, Grund (Austria). D1–D3. paratype, NHMW 1855/0002/0007b, Grund (Austria).