Bairdiacypris argonautaii Forel 2020, sp. nov.
Creators: name: Forel, Marie-Béatrice
name: Grădinaru, Eugen
Publisher: name: Zenodo
Year: 2020
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Ostracoda
Podocopida
Bairdiidae
Bairdiacypris
Bairdiacypris argonautaii

description: Bairdiacypris argonautaii Forel sp. nov.
urn:lsid:zoobank.org:act: 4AF32BE0-8E7A-4ABD-BCC8-42D2F99F451F
Fig. 6 F–O
Bairdiacypris? aff. Bairdiacypris sp. A Bolz – Mette & Mohtat-Aghai 1999: pl. 3, fig. 7.
Diagnosis
A new species ovoid in shape, with overlap interrupted at AVB and PVB, RV preplete and LV amplete to postplete.
Etymology
From the ancient Greek Αργοναῦται, Argonautai, referring to the mythological heroes, the argonauts, who travelled the Black Sea searching for the golden fleece.
Material examined
Holotype
AUSTRIA • 1 RV; Northern Calcareous Alps, Tyrol; Kössen Formation, Rhaetian, Upper Triassic (Mette & Mohtat-Aghai 1999: pl. 3, fig. 7); University of Innsbruck, Austria.
Paratypes
ROMANIA • 1 RV; Black Sea, Romanian Continental Shelf, borehole 817LV, sample CM31A; Rhaetian,
Upper Triassic; MNHN.F. F63201 • 1 complete carapace; same collection data as for preceding; Rhaetian, Upper Triassic; MNHN.F. F63202.
Other material
ROMANIA • 1 complete carapace; Black Sea, Romanian Continental Shelf, borehole 817LV, sample CM31A; Rhaetian, Upper Triassic; MNHN.F. F63203 • 1 complete carapace; same collection data as for preceding; Rhaetian, Upper Triassic; MNHN.F. F63204 • 1 complete carapace; same collection data as for preceding; Rhaetian, Upper Triassic; MNHN.F. F63206 • 1 complete carapace; same collection data as for preceding; Rhaetian, Upper Triassic; MNHN.F. F63207 • 1 complete carapace; same locality as for preceding but sample CM31B; Rhaetian, Upper Triassic; MNHN.F. F63205 • 1 complete carapace; same collection data as for preceding; Rhaetian, Upper Triassic; MNHN.F. F63208.
Dimensions
See Fig. 3B.
Description
CARAPACE. Very large, massive, ovoid in lateral view with L max below mid-H at both valves; LV larger than RV, overlapping it all along dorsal margin with maximum at DB, and along VB, overlap interrupted along AVB and PVB; biconvex in dorsal view with W max behind L max, overlapping area seemingly flat; surface smooth.
RV. Subrectangular with H max at antero-dorsal angulation; dorsal margin tripartite with dulled angulations; PDB straight to slightly convex in young instars, short (12–21% of L max) and steeply sloping to PB (60–70°); DB straight, moderately sloping to postero-dorsal angulation (10–20°) with length increasing through ontogeny; ADB straight, long, with relatively constant length through ontogeny (37–45% of L), sloping toward AB with an angle ranging from 20° to 40°; AB large, relatively bairdiid in shape, with maximum of curvature at or slightly below mid-H; ventral margin long and sinuous; AVB steeply raised
to AB and largely convex to close to vertical in young instars; VB with tenuous oral concavity mid-L; PVB short, convex, only slightly raised to PB; PB at lower ¼ of H max, relatively narrow, gently rounded to only slightly bairdiid in shape.
LV. Ovoid with H max behind mid-H in large forms, at antero-dorsal angulation in younger instars; dorsal margin gently rounded with dulled angulations in young instars that are unrecognizable in larger instars and adults; ventral margin long and straight to gently convex.
Occurrence
Kössen Formation, Northern Calcareous Alps, Tyrol, Austria, Rhaetian, Upper Triassic (Mette & MohtatAghai 1999); Romanian Continental Shelf, Black Sea, Rhaetian, Upper Triassic (this paper).
Remarks
Bairdiacypris argonautaii sp. nov. is higher and shorter than “ Bairdia ” raetica Bolz, 1971 from the Rhaetian interval, Late Triassic, of Tyrol (Bolz 1971b); it also differs by the antero-ventral and postero-ventral interruption of the overlap, dorsal margin tripartite with pronounced antero-dorsal and postero-dorsal angulations and anterior margin larger. Bairdiacypris argonautaii sp. nov. is also close to Bairdiacypris sp. in Kristan-Tollmann et al. 1979 from the Rhaetian, Late Triassic, of Iran (KristanTollmann et al. 1979) but the only illustrated Iranian specimen shows a continuous overlap along AVB and PVB and a posterior maximum of convexity located higher resulting in subsymmetric anterior and posterior borders. Bairdiacypris argonautaii sp. nov. is also morphologically close to Bairdia cf. peneovoidea Bolz, 1971 from the Rhaetian, Late Triassic, of Iran (Kristan-Tollmann et al. 1979) but has a more rounded AVB and a larger PB. The dimensions of all specimens attributed to B. argonautaii sp. nov. are plotted in Fig. 3B. The largest specimen known to date is a right valve from the Rhaetian of Tyrol (Mette & Mohtat-Aghai 1999). All specimens found in the present investigation are distributed across at least six successive ontogenetic stages, all smaller than the specimen from Mette & Mohtat-Aghai (1999). The ontogenetic development of B. argonautaii sp. nov. is mainly marked by an enlargement of the posterior end of the carapace.
description: Published as part of Forel, Marie-Béatrice & Grădinaru, Eugen, 2020, Rhaetian (Late Triassic) ostracods (Crustacea, Ostracoda) from the offshore prolongation of the North Dobrogean Orogen into the Romanian Black Sea shelf, pp. 1-83 in European Journal of Taxonomy 727 on pages 19-22, DOI: 10.5852/ejt.2020.727.1183, http://zenodo.org/record/4316845