Alfaites

1624511B-F2C2-4964-A4D2-CF072FF24D61


Introduction
Hyoliths represent a group of extinct Palaeozoic invertebrates with originally aragonitic shells whose precise systematic affinity remains unclear.
The group Hyolitha is usually divided into two main orders.The order Orthothecida Marek, 1966 represents hyoliths with a conical shell of diverse cross-section (circular, elliptical, kidney-shape...) and planar aperture with retractable planar or slightly concave operculum.The order Hyolithida Sysoev, 1957 is characterized by a shell of diverse cross-section (triangular, oval, etc.) with prolonged venter, corresponding non-retractable operculum and paired curved appendages called helens which protrude from the spaces between conch and operculum.
Hyoliths have been often classified as incertae sedis (e.g., Bengston et al. 1990;Devaere et al. 2014), as a group of mollusks (e.g., Malinky & Yochelson 2007;Marek & Yochelson 1976) or as a separate phylum (e.g., Kouchinsky 2000;Runnegar et al. 1975).The taxonomic placement of hyolithids was recently discussed by Martí Mús (2016) and Moysiuk et al. (2017), who suggested that hyoliths show a strong affinity to the Palaeozoic lophophorates, mainly to brachiopods.This interpretation was based on excellently preserved hyolithid material with clearly distinct soft parts.The recent paper of Moore & Porter (2018) supports this statement based on study of the microstructure of conchs and opercula.
In the second half of the twentieth century, a large collection of several hundred hyolith conchs and opercula was gathered by Petr Šlehofer and Ladislav Marek (Academy of Science Prague) at numerous outcrops of the Skryje-Týřovice Basin (Marek 1983).Some of these materials were described in a series of papers by Marek (1972Marek ( , 1975Marek ( , 1980Marek ( , 1981; see also summary by Malinky & Yochelson 2007).This extensive collection was transferred from the Academy of Science to the National Museum, Prague, in 1998.Here, the original hyolith material was newly sorted and specimens belonging to still-undescribed or poorly known taxa were selected for study, leading to the successful description of material from Marek's original collection (Valent et al. 2013(Valent et al. , 2017)).
Insufficient material of other species has been complemented by more recently collected specimens and described by a team of authors, particularly by the amateur collectors Václav Micka (Prague), Michal Szabad (Příbram) and Václav Vokáč (Plzeň), who provided additional specimens and important data on geographic and stratigraphic distribution of individual taxa (Valent et al. 2011(Valent et al. , 2012)).
The aim of this contribution is to describe the new hyolithid Alfaites romeo gen.et sp.nov.recognized by the late Ladislav Marek in an unpublished manuscript dating from the early 1980s (Marek 1983).This rare form is restricted to the Biskoupky, Buchava and Hradiště localities in the Skryje-Týřovice Basin.
The Skryje-Týřovice Basin is one of several regions where Cambrian fossils are known in the Czech Republic (Fig. 1A-B; Geyer et al. 2008).Middle Cambrian sediments of the Buchava Formation belong to a classical repository of Cambrian fauna (Geyer et al. 2008), present in outcrops at the north-western edge of the Late Cambrian Křivoklát-Rokycany Volcanic Complex (Fig. 1C-D).

Distribution
Alfaites romeo gen.et sp.nov.has been reported from the Biskoupky, Buchava, and Hradiště localities, all situated in the south-western part of the Skryje-Týřovice Basin (Fig. 1D).
Hradiště locality.Natural outcrops in a forested hill-slope belonging to the lower third of the Buchava Formation (Fig. 1E).This outcrop was mentioned by Valent et al. (2015) as one of the localities yielding the rare hyolithids Skryjelites auritus Valent et al., 2015 andQuasimolites quasimodo Valent et al., 2015.The occurrence of the agnostid Peronopsis associated with Paradoxides (Eccaparadoxides) pusillus (Barrande, 1846), diverse paradoxidid and other trilobites, brachiopods and echinoderms established at the Biskoupky, Buchava and Hradiště localities (for the list of associated taxa at Biskoupky see Fatka et al. in press; at Buchava see Marek 1975), indicates a biostratigraphic age equivalent to the Caesaraugustian Regional Stage in the West Gondwanan chronostratigraphic scale (see Geyer et al. 2008) and thus corresponds to the Drumian Stage of Cambrian Series 3 (Fig. 1E).

Photography and collection
The specimens were studied using an Olympus SZX-12 optical stereo zoom microscope.External moulds and latex casts were coated with ammonium chloride and photographed using an Olympus DP72 digital camera.Helicon Focus software was used to stack the images for sufficient depth of focus.All illustrated specimens are held in the collections of the Palaeontological Department, National Museum, Cirkusová 1740, 193 00 Praha 9 -Horní Počernice, Czech Republic, registered with the prefix NM L. The material was collected by the late Ladislav Marek and Pavel Šlehofer (Czech Academy of Science).

Type species
Alfaites romeo sp.nov.

Etymology
The name 'Alfaites' refers to the first letter of Greek alphabet -alpha.The cross-section of the conch (Fig. 2H) resembles the large letter alpha and the small letter alpha (turned 90° clockwise) can also be discerned in Fig. 2C.

Diagnosis
Conch with almost flat slopes of dorsal side; dorsal side broadly rounded; ventral side very slightly vaulted to almost flat; lateral edges sharply rounded.Subtriangular cross-section.Amblygonal aperture.Sculpture of conch consists of transverse rarely anastomosing ribs.No apical septa were found.
Monoclaviculate operculum with clavicles of bow-shaped transverse cross-section.Open margins of clavicles overlap above inner surface operculum (interclavicular concavity).Distal ends of clavicles cut off.Bases of cardinal processes diverge at 90° angle.Uncommon and relatively robust cardinal teeth developed along the dorsal margin.Rooflets distinct.Sculpture of operculum consisting growth-lines and fine radial ribs.

Remarks
Morphology of both conch and operculum does not allow the classification of Alfaites gen.nov. to any known family of the order Hyolithida.This genus resembles Carinolithes Sysoev, 1958 as emended by Berg-Madsen & Malinky (1999) in the morphology of the cardinal processes, but the operculum of Alfaites gen.nov. is monoclaviculate, thus differing from the platyclaviculate operculum of Carinolithes.Similarly, the shape of the transverse cross-section of the conch (subtriangular in Alfaites and rounded -triangular with distinct keel on dorsum in Carinolithes) and the sculpture (distinct transverse ribs in Alfaites and usually fine growth-lines in Carinolithes) are different.The genus Alfaites, including its type species A. romeo sp.nov., was first recognized as a separate taxon in an unpublished report by the late Ladislav Marek (1983: 36-38).

Referred material
In addition to the holotype and paratypes, parts of another three conchs and five opercula (collection NM Ls 858), all deposited in collections of the National Museum (Prague, Czech Republic).

Diagnosis
As for the genus.

Description
Monoclaviculate operculum with clavicles of bow-shaped transverse cross-section.The angle of divergence of clavicles reaches 135° on the type specimen (NM L46640).Open margins of clavicles overlap above the inner surface operculum (interclavicular concavity).Distal ends of clavicles cut off.Cardinal processes broadly divergent with rounded distal ends, mutually separated by a narrow and shallow groove in linear axis of operculum.Bases of cardinal processes diverging at an angle of 90° toward the dorsal margin of operculum.Uncommon and relatively robust cardinal teeth are developed along the dorsal margin.Cardinal shield is concave in centre and slightly vaulted at the sides.Rooflets clearly distinct and bordered by grooves.Sculpture of operculum consists of growth-lines and fine radial ribs, more distinct near anterior margin of conical shield.Area of operculum adjacent to summit of operculum is nearly smooth.Width and length of inner side operculum is 8.8 mm and 5.5 mm for holotype NM L44640, 7.7 mm and 4.7 mm for paratype NM L44642; width and length of outer side of operculum is 7.6 mm and 4.9 mm for paratype NM L44641 and 6.7 mm and 4.7 mm for paratype NM L44646.Length of the conical shield is 4.0 mm for paratype NM L44641 and 3.7 mm for paratype NM L44646.
Conch with subtriangular cross-section.Ventral side very slightly vaulted to almost flat; lateral edges sharply rounded; dorsal side strongly rounded.Amblygonal aperture with dorsal margins vaulted slightly forwardly.The w/h index of conch at aperture is 2.2 (width of aperture of specimen NM L46645 is 7.1 mm and height is 3.2 mm).No apical septa were found.Sculpture consists of transverse rarely anastomosing ribs, which are asymmetrical in transverse cross-section.Ventral side bears only indistinct growth-lines.Conch attained minimum length 30 mm.

Occurrence
This rare species has been found only at the Biskoupky, Buchava and Hradiště localities.

Remarks
In his manuscript, Marek (1983) stated that the material collected from the above localities contained another species closely related to Alfaites romeo sp.nov., but presenting opercula with distinctly more vaulted conical shields, higher cardinal shields and a more rounded outline.He even marked the box of one specimen (NM L46646, Fig. 2D) as "Alfaites julia" sp.nov., but no significant differences could be observed upon study of the available material.

Discussion
The Cambrian fossils of the Barrandian region have been intensively collected and studied since the beginning of the 19 th century.Despite such a long tradition, careful collecting still provides undescribed invertebrate taxa like those occurring only at several localities and/or those restricted exclusively to one small outcrop (e.g., Fatka & Herynk 2016;Valent et al. 2017).The late Dr Ladislav Marek (in cooperation with P. Šlehofer) gathered a large collection of Cambrian and Ordovician hyoliths.The Cambrian hyolith material was colleted from numerous "classical" and well known outcrops as well as from small and occasional excavations.The acquired material was only partly published (Marek 1972(Marek , 1975(Marek , 1980(Marek , 1981)), while the larger part of Marek's study was summarized in an unpublished report (Marek 1983).Thanks to the monograph of Barrande (1867) and the more recent studies of Marek (1972Marek ( -1981)), Cambrian hyoliths of the Barrandian area represent a classical repository of this group.The hyolith taxa first distinguished by Marek have since been completed by more recently collected specimens and published one by one (Valent et al. 2011(Valent et al. , 2012(Valent et al. , 2013(Valent et al. , 2015(Valent et al. , 2017)).

Fig. 1 .
Fig. 1.Maps showing the location of fossil sites in the middle Cambrian Buchava Formation within the Skryje-Týřovice Basin, Central Bohemia. A. Map of Europe with the Czech Republic.B. Map of the Czech Republic showing distribution of Palaeozoic rocks of Barrandian area.C. Simplified sketch map of the Skryje-Týřovice Basin.D. Geological map showing distribution of middle Cambrian Buchava Formation and location of the Buchava, Hradiště and Biskoupky localities.E. Stratigraphic position of the Buchava, Hradiště and Biskoupky localities and range of Alfaites romeo gen.et sp.nov.Geology modified from Mašek et al. (1997) and Vorel et al. (2014); lithostratigraphy and biostratigraphy after Fatka et al. (2011) and Vokáč (2002). 1 = Biskoupky locality; 2 = Buchava locality; 3 = Hradiště locality.

2 Etymology
gen. et sp.nov.urn:lsid:zoobank.org:act:2EA9355A-4894-4F7B-AFDA-1000BCE24C3CFig.The specific epithet 'romeo' refers to the Shakespeare's protagonist Romeo Montague.Marek initially planned to describe two closely related taxa as A. romeo and A. julia.The only specimen designated as A. julia (Fig. 2D) in the original collection of L. Marek does not show any difference in morphology and should be classified as A. romeo.Material examined Holotype CZECH REPUBLIC -Skryje-Týřovice Basin • Inner side of operculum; NM L46640.Paratypes CZECH REPUBLIC -Skryje-Týřovice Basin • Inner side of operculum; NM L46642 • External sides of operculum; NM L46646, NM L46641 • Inner mould of conch; NM L46645 • External moulds of conchs; NM L46643, L46644.