Clathrospira Ulrich & Scofield, 1897

Genus Clathrospira Ulrich & Scofield, 1897

Type species: Pleurotomaria subconica Hall, 1847 , by original designation; from the Middle Ordovician of North America .

Remarks.—Members of Clathrospira have a turbiniform and narrowly phaneromphalous shell, with a conical spire and shallow sutures, growth lines that are strongly prosocline above selenizone and strongly opisthocline below it, but rounding to gently prosocline on base, outlining a moderately deep labral sinus that culminates in a short slit; selenizone bordered by fine threads; growth lines and lunulae periodically strengthened, very fine and numerous spiral threads ( Knight et al. 1960).

According to Horný (1997), the genus is imperfectly known and defined, lacks modern revision and its interpretation is rather wide ( Ulrich and Scofield 1897; Longstaff 1924; Koken and Perner 1925; Vostokova 1955; Wagner 2002). Horný (1997) pointed out that the single modern detailed paper concerning one European species, Clathrospira elliptica ( Hisinger, 1831) from the Oslo region, is that of Yochelson (1963). However, C. elliptica has later been revised by Wager (2002) and Frisk and Ebbestad (2007).

The very fine revolving lira, a character which is present in the type species, has not been largely accepted as diagnostic of Clathrospira (see Horný, 1997: 57). The genus is also diagnosed by having a very strong bilineate peripheral band that is located very low on the whorl owing to a very short left ramp relative to the right ramp ( Wagner 2002).

Karapunar et al. (2022) argued that Pleurotomariida have the most extended fossil record among the living gastropods with one of their oldest occurrences in the Ordovician with the genus Clathrospira ( Horný 1997; Wagner 2002; this paper). According to Karapunar et al. (2022), Pleurotomariida was the most diversified gastropod group in the middle and late Palaeozoic and dominant in shallow water communities at that time.

The report of the genus Clathrospira , and the new species Clathrospira gondwanica sp. nov. (see below), in the Upper Ordovician of the Argentine Precordillera, provides new and updated taxonomic information enabling to interpret the origin of the order Pleurotomariida in South America at about 458.4–445.2 Mya.

Stratigraphic and geographic range.—Middle Ordovician– Silurian; North America, South America and Europe.