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Leionucula rakhiensis

Bivalvia - Protobranchia - Nuculidae

Taxonomy
Leionucula rakhiensis was named by Eames (1951) [DISTRIBUTION: Eocene; Pakistan.]. Its type specimen is L. 79825, a shell, and it is not a trace fossil. Its type locality is Fossil Bed F.1986, Rakhi Nala, which is in a Bartonian marine shale in the Drazinda Formation of Pakistan.

Synonymy list
YearName and author
1951Leionucula rakhiensis Eames p. 320 figs. pl. 10, figs. 20a, b

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RankNameAuthor
kingdomAnimalia()
Bilateria
EubilateriaAx 1987
Protostomia
Spiralia
superphylumLophotrochozoa
phylumMollusca
classBivalvia
RankNameAuthor
orderProtobranchiaPelseneer 1889
superorderNuculiformiiDall 1889
orderNuculida(Dall 1889)
superfamilyNuculoidea(Gray 1824)
familyNuculidaeGray 1824
genusLeionuculaLamarck 1799
speciesrakhiensis

If no rank is listed, the taxon is considered an unranked clade in modern classifications. Ranks may be repeated or presented in the wrong order because authors working on different parts of the classification may disagree about how to rank taxa.

Diagnosis
ReferenceDiagnosis
F. E. Eames 1951No traces of any radial shell structure. Shell apparently not very thick, of
moderate size, oval-subtriangular in outline, moderately elongate, not very strongly
inflated. Umbos small, not high, situated posterior to the middle line at about one-third
of the length. Antero-dorsal margin moderately long, almost straight, very slightly convex,
gently descendent. ,\nterior end rather narrowly rounded. Ventral margin moderately
convex, the convexity appearing to be somewhat variable. Posterior end bluntly angular,
there being a tendency for the posterior portion of the ventral margin to be more steeply
ascendent than the anterior portion. Postero-dorsal margin not very short, only moderately
steeply descendent, practically straight. Surface showing traces of fine concentric threads,
which are about half as wide as their intervals, and of very fine growth lines. There are
11 threads in 3 mm. on the antero-ventral portion of one of the topotypes. Lunule long
and narrow, moderately depressed as a whole, but projecting along the median line, the
projection being more marked away from the umbonal region; outer edge limited by a
vague, blunt ridge. Escutcheon cordiform, its other characters like those of the lunule.
Valve margins internally smooth ventrally. Traces of taxodont teeth can be seen on the
dorsal margins of some of the topotypes. Antero-dorsal margin of posterior adductor scar
and postero-dorsal margin of anterior adductor scar a.ppearing to have been more impressed than the remainder of their surfaces.