Rhagasostoma gibbosulum Brydone, 1936

Koromyslova, Anna V., Taylor, Paul D., Martha, Silviu O. & Riley, Matthew, 2018, Rhagasostoma (Bryozoa) from the Late Cretaceous of Eurasia: taxonomic revision, stratigraphy and palaeobiogeography, European Journal of Taxonomy 490, pp. 1-66 : 35-38

publication ID

https://doi.org/ 10.5852/ejt.2018.490

publication LSID

lsid:zoobank.org:pub:BE023137-CC5E-4DC5-94F6-B549BB140361

DOI

https://doi.org/10.5281/zenodo.3849982

persistent identifier

https://treatment.plazi.org/id/03D587D7-9654-FF8B-F330-F961FD36F929

treatment provided by

Valdenar

scientific name

Rhagasostoma gibbosulum Brydone, 1936
status

 

Rhagasostoma gibbosulum Brydone, 1936

Fig. 14 View Fig , Table 8 View Table 8

Rhagasostoma gibbosulum Brydone, 1936: 74 , pl. 36, fig. 1.

Material studied

Holotype

UNITED KINGDOM • England, High Down; middle Campanian ( Belemnitella mucronata Zone ) of Isle of Wight; SM B36887 ( Fig. 14 View Fig A–D; figured by Brydone 1936: pl. 36, fig. 1).

Additional figured material

BELARUS • Grodno Region; erratic block of?late Campanian age in a quarry near Hrodna / Grodno (Гродна/ Гродно); PIN 2922 View Materials /242 ( Fig. 14 View Fig E–F) .

GERMANY • 4 specs; Schleswig-Holstein, Saturn quarry near Kronsmoor; early Maastrichtian ; SMF 29908 ( Fig. 14G View Fig ), 29909 ( Fig. 14H View Fig ), 29911 ( Fig. 14I View Fig ), 29912 ( Fig. 14J View Fig ) .

Other material

GERMANY • 2 specs; same data as for preceding; SMF 29910, 29913 About SMF .

Description

Colony erect, with flattened bifoliate branches (1–6 mm wide). Ancestrula and early astogeny not observed.Autozooids variable in shape, often broad and roundish; zooidal boundaries raised.Gymnocyst? present proximolaterally, smooth ( Fig. 14B, G, I View Fig ), but usually not visible. Cryptocyst extensive, finely pustulose, usually slightly convex centrally. Opesia terminal or subterminal, semielliptical, delineated by two walls, a thin inner wall forming the distolateral rim and a projecting and thickened outer wall forming the proximolateral rim. Proximal edge of opesia straight, smooth, with outgrowths at the two proximolateral corners delineating small opesiules; outgrowths often destroyed, giving the opesiules the appearance of opesiular indentations ( Fig. 14C View Fig , I–J). Septula not observed. Ovicells endozooidal, ooecium is formed by the distal zooid, well-recognizable, with cryptocyst-like surface and arch-like proximal edge with elongated proximolateral processes extending along the cryptocyst of the maternal zooid ( Fig. 14I View Fig ). Avicularia interzooidal, smaller than autozooids, elongate. Rostrum channeled, asymmetrical, rarely symmetrical, with elevated wing-like walls and a pointed tip, rising above the surface of the colony and tilted to the right or left, rostral tip not reaching the opesia of distal autozooid. Rostrum tilted over gymnocyst of the distal autozooid or ooecium. Wedge-like structures present ( Fig. 14 View Fig I–J), extending from the base to the middle of the rostrum and partially covering the opesia, but often these structures are broken ( Fig. 14D View Fig ). Proximal part of avicularium rounded, shorter and wider than rostrum, cryptocyst pustulose, concave, but often not visible. Opesia round with two short teeth proximally, opesiules lacking ( Fig. 14J View Fig ). Kenozooids sometimes numerous, located along edges of branches, roundish ( Fig. 14H View Fig ). Cryptocyst finely pustulose. Opesia round. Intramural reparative kenozooidal buds in host autozooids sometimes observed ( Fig. 14B View Fig ), all with the same polarity as the host zooid. Closure plates and intramural reparative budding of autozooids and avicularia not observed.

Remarks

Rhagasostoma gibbosulum can be distinguished from R. gibbosum by the convex border of the cryptocyst and the inferred, well-developed gymnocyst.

Distribution

Middle Campanian United Kingdom: High Down, Isle of Wight, England. Late Campanian Belarus: Quarry near Hrodna / Grodno (Гродна/ Гродно), Grodno Region. Early Maastrichtian Germany: Saturn quarry, near Kronsmoor, Schleswig-Holstein.

Table 8. Summary of measurements of Rhagasostoma gibbosulum Brydone, 1936. For each parameter the range is given with the number of measurements in brackets. The arithmetic mean is given ± standard deviation. All measurements in µm.

Basin Stratigraphy Locality Southern North Sea Basin Early Maastrichtian Norfolk North German Basin Early Maastrichtian Kronsmoor Polish Basin?Late Campanian Grodno Region Total
  AzL 330–510 (6) 420.00 ± 75.37 410–880 (18) 558.33 ± 108.97 390–480 (6) 435.00 ± 32.09 330–880 (30) 506.00 ± 111.31
  AzW 240–320 (6) 283.33 ± 27.33 320–520 (18) 416.11 ± 45.26 260–360 (6) 316.67 ± 35.02 240–520 (30) 369.67 ± 70.73
Autozooids OpL OpW GL 80–110 (6) 100.00 ± 12.65 110–140 (6) 126.67 ± 13.66 60–130 (6) 100.00 ± 29.66 80–140 (18) 108.89 ± 16.05 110–150 (18) 131.67 ± 14.65 50–370 (18) 152.78 ± 79.40 90–130 (6) 106.67 ± 13.66 120–130 (6) 126.67 ± 5.16 50–120 (3) 80.00 ± 36.06 80–140 (30) 106.67 ± 14.93 110–150 (30) 129.67 ± 12.99 50–370 (27) 132.96 ± 72.37
  OoL OoW Not observed 260–270 (3) 263.33 ± 5.77 230–360 (3) 293.33 ± 65.06 Not observed 260–270 (3) 263.33 ± 5.77 230–360 (3) 293.33 ± 65.06
  AvL 160–270 (6) 226.67 ± 37.24 250–470 (14) 367.86 ± 76.98 320–390 (6) 320.00 ± 47.33 160–470 (26) 324.23 ± 84.62
  RL 90–180 (6) 141.67 ± 32.51 170–390 (14) 267.14 ± 69.22 140–240 (6) 193.33 ± 39.83 90–390 (26) 221.15 ± 76.85
  W–lSL Not observed 140–190 (6) 160.00 ± 16.73 Not observed 140–190 (6) 160.00 ± 16.73
Avicularia RW PrL 70–140 (6) 93.33 ± 25.03 70–140 (6) 95.00 ± 25.88 70–140 (14) 105.71 ± 20.65 70–190 (14) 114.29 ± 33.22 80–120 (6) 98.33 ± 14.72 70–140 (6) 105.00 ± 26.65 70–140 (26) 101.15 ± 20.46 70–190 (26) 107.69 ± 30.24
  PrW 60–130 (6) 91.67 ± 29.27 70–150 (14) 104.29 ± 23.11 90–130 (6) 101.67 ± 16.02 60–150 (26) 100.77 ± 22.96
  OpL OpW Not observed 40–80 (8) 61.25 ± 12.46 30–70 (8) 52.50 ± 16.69 40–80 (4) 55.00 ± 19.15 40–70 (4) 47.50 ± 15.00 40–80 (12) 59.17 ± 14.43 30–70 (12) 50.83 ± 15.64
Kenozooids KzL KzW OpD 380–400 (2) 390 ± 14.14 270–300 (2) 285.00 ± 21.21 20–30 (2) 25.00 ± 7.07 180–370 (14) 261.43 ± 67.24 180–390 (14) 272.86 ± 69.99 20–40 (15) 24.67 ± 6.40 130–270 (4) 207.50 ± 64.49 130–200 (4) 172.50 ± 29.86 20–60 (4) 30.00 ± 20.00 130–400 (20) 263.50 ± 78.15 130–390 (20) 254.00 ± 72.65 20–60 (21) 25.71 ± 9.78
SM

Sarawak Museum

SMF

Forschungsinstitut und Natur-Museum Senckenberg

Kingdom

Animalia

Phylum

Bryozoa

Class

Gymnolaemata

Order

Cheilostomatida

Family

Onychocellidae

Genus

Rhagasostoma

Loc

Rhagasostoma gibbosulum Brydone, 1936

Koromyslova, Anna V., Taylor, Paul D., Martha, Silviu O. & Riley, Matthew 2018
2018
Loc

Rhagasostoma gibbosulum

Brydone R. M. 1936: 74
1936
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