Bairdiacypris argonautaii Forel, 2020

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, European Journal of Taxonomy 727, pp. 1-83 : 19-22

publication ID

https://doi.org/ 10.5852/ejt.2020.727.1183

publication LSID

lsid:zoobank.org:pub:85AF63D9-5E9E-4CE0-AEC6-6F7CC8C4D375

DOI

https://doi.org/10.5281/zenodo.4340781

persistent identifier

https://treatment.plazi.org/id/4AF32BE0-8E7A-4ABD-BCC8-42D2F99F451F

taxon LSID

lsid:zoobank.org:act:4AF32BE0-8E7A-4ABD-BCC8-42D2F99F451F

treatment provided by

Plazi

scientific name

Bairdiacypris argonautaii Forel
status

sp. nov.

Bairdiacypris argonautaii Forel View in CoL sp. nov.

urn:lsid:zoobank.org:act:4AF32BE0-8E7A-4ABD-BCC8-42D2F99F451F

Fig. 6 View Fig 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 View Materials 1 complete carapace; same collection data as for preceding; Rhaetian, Upper Triassic; MNHN.F. F63202 View Materials .

Other material

ROMANIA • 1 complete carapace; Black Sea, Romanian Continental Shelf, borehole 817LV, sample CM31A; Rhaetian, Upper Triassic; MNHN.F. F63203 View Materials 1 complete carapace; same collection data as for preceding; Rhaetian, Upper Triassic; MNHN.F. F63204 View Materials 1 complete carapace; same collection data as for preceding; Rhaetian, Upper Triassic; MNHN.F. F63206 View Materials 1 complete carapace; same collection data as for preceding; Rhaetian, Upper Triassic; MNHN.F. F63207 View Materials 1 complete carapace; same locality as for preceding but sample CM31B; Rhaetian, Upper Triassic; MNHN.F. F63205 View Materials 1 complete carapace; same collection data as for preceding; Rhaetian, Upper Triassic; MNHN.F. F63208 View Materials .

Dimensions

See Fig. 3B View Fig .

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 View Fig . 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.

Kingdom

Animalia

Phylum

Arthropoda

Class

Ostracoda

Order

Podocopida

Family

Bairdiidae

Genus

Bairdiacypris

Loc

Bairdiacypris argonautaii Forel

Forel, Marie-Béatrice & Grădinaru, Eugen 2020
2020
Loc

Bairdiacypris sp

Bradfield 1935
1935
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