Radula patrickmuelleri K.Feldberg, Schaef .-Verw. & M.A.M.Renner, 2022
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publication ID |
https://dx.doi.org/10.3897/fr.25.82362 |
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publication LSID |
lsid:zoobank.org:pub:45048AF3-36F0-4E93-AB96-07BE0F9258D9 |
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persistent identifier |
https://treatment.plazi.org/id/2CC0D59C-44E5-4B9B-B81A-5D40606F24DF |
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taxon LSID |
lsid:zoobank.org:act:2CC0D59C-44E5-4B9B-B81A-5D40606F24DF |
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treatment provided by |
by Pensoft |
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scientific name |
Radula patrickmuelleri K.Feldberg, Schaef .-Verw. & M.A.M.Renner |
| status |
sp. nov. |
Radula patrickmuelleri K.Feldberg, Schaef.-Verw. & M.A.M.Renner sp. nov.
Figs 3 View Figure 3 , 4A-E View Figure 4
Holotype.
GZG.BST.22041 ( Müller BuB4395), Geoscience Centre (GZG) at the University of Göttingen, Germany.
Etymology.
The specific epithet honors the amber collector Patrick Müller ( Zweibrücken, Germany) who generously supports our research by providing numerous amber fossils for study.
Locality and horizon.
Amber mines southwest of the village of Tanai ca. 105 km north of Myitkyina in Kachin State, northern Myanmar, fossil enclosed in upper Albian-lower Cenomanian Kachin amber.
Diagnosis.
Gametophyte with zig-zagged stems and complicate bilobed lateral leaves; dorsal lobe oblong-elliptic with broadly rounded to obtuse apex; ventral lobule small, Lejeunea -type, longitudinally inserted, rounded rectangular to ovate with subacute to rounded apex, inner margin not ampliate, not exceeding stem; irregularly shaped gemmae produced on lobe margins.
Description.
Unbranched gametophyte fragment ca. 4.84 mm long, yellowish to reddish brown (Fig. 3A-D View Figure 3 ); main shoot 1.68-2.28 mm wide with leaves. Stem dark reddish brown, distinctly zig-zagged, ca. 60 µm wide [numbers of cell rows not clearly visible, possibly 4-5]; surface cells elongated, 2-3 × as long as wide; ventral and dorsal leaf-free strips ca. 2 cells wide. One rhizoid bundle visible on the lobule of a basal leaf (Fig. 3E View Figure 3 ), bundle 7.5-10 µm wide, rhizoids up to 130 µm long. Foliation incubous, lateral leaves alternate, complicate bilobed, divided into large dorsal lobe and smaller ventral Lejeunea -type lobule enclosing the ventral leaf surface and forming a sharp postical keel (Fig. 3D-F View Figure 3 ). Dorsal lobes imbricate, oblong-elliptic, longer than wide, nearly flat, spreading to more erect on upper part of shoot, but not obliquely patent (Fig. 3A-D View Figure 3 ); margin entire to slightly crenulate due to gemmae production; postical margin slightly emarginated at end of keel, then regularly arched towards apex, apex broadly rounded to obtuse, antical margin regularly arched and nearly parallel to postical margin in the lobe middle, abruptly curved near stem and forming an angle of ca. 90° to the inner margin, inner margin not ampliate, extending onto the dorsal stem surface up to 0.5-1 × the stem width; lobe 550-600 µm long × 340-420 µm wide, length:width ratio 1.3-1.7:1, length exterior to keel 410-510 µm, length of stem insertion ca. 170-190 µm [not clearly visible on most leaves]. Cells of lobe margin quadrate to rectangular, 10-20 µm long × 15-25 µm wide, long axis parallel with leaf margin; medial cells hexagonal, mostly isodiametric to occasionally weakly elongated, 20-35 µm long × 20-30 µm wide; basal cells of the same size or slightly larger than medial cells, 20-40 µm long × 20-35 µm wide (Fig. 4A, B View Figure 4 ); cell walls thin, with small, triangular trigones possibly present at cell angles; free exterior wall of marginal cells unthickened. Ventral lobules small in relation to lobe (<0.2 ×), rounded rectangular to ovate, insertion longitudinal, exterior margin curved, antical margin slightly curved or nearly straight, interior margin not ampliate, barely extending onto the stem surface (Fig. 3D-F View Figure 3 ), apex subacute to broadly rounded; keel emerging at an angle of ca. 45° from the stem, slightly convex; lobule ca. 150 µm long × ca. 150 µm wide, length:width ratio 0.9-1.1:1, keel length 140-160 µm, length of stem insertion 90-140 µm. Underleaves lacking. Asexual reproduction by gemmae produced from cells of leaf margin (Fig. 4B-E View Figure 4 , indicated by asterisks), gemmae possibly unistratose, subdiscoid to obcordate to irregularly thalloid as size increases, 20-110 µm long × 25-70 µm wide, first cell division seemingly periclinal (Fig. 4C, E View Figure 4 ); stalk cell of gemmae rectangular. Sterile.
Remarks.
This fossil consists of a short, sterile gametophyte fragment but shows all relevant characters to delimitate it from other Radula fossils from Kachin amber (Figs 3 View Figure 3 , 4A-E View Figure 4 ). The small, rounded rectangular to ovate lobules allow to differentiate it from R. heinrichsii as well as R. tanaiensis which have much larger lobules (Fig. 5A, B View Figure 5 ), and the apically rounded lobes with nearly parallel margins distinguish it from R. cretacea (Fig. 4F View Figure 4 ).
No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.