Rhagasostoma inelegans ( Lonsdale, 1850 )

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 : 8-13

publication ID	https://doi.org/10.5852/ejt.2018.490
publication LSID	lsid:zoobank.org:pub:BE023137-CC5E-4DC5-94F6-B549BB140361
persistent identifier	https://treatment.plazi.org/id/03D587D7-9671-FFA2-F330-FED8FCB7FECF
treatment provided by	Valdenar (2020-05-16 13:59:28, last updated 2020-05-16 14:14:48)
scientific name	Rhagasostoma inelegans ( Lonsdale, 1850 )
status	sp. nov.

Treatment

Rhagasostoma inelegans ( Lonsdale, 1850)

Figs 3–4, Table 1

Flustra ? inelegans Lonsdale, 1850: 319 , pl. 18.B, figs 9,?10, 11.

Rhagasostoma inelegans var. angliae Brydone, 1936 pars: 74, pl. 35, fig. 8. Syn. nov.

Rhagasostoma inelegans – Brydone 1930 pars: 47, pl. 26, figs?1, 2–3.

Onychocella inelegans – Voigt 1975: 245, pl. 5, figs 1–4. — Taylor 1991: 33, pl. 7, fig. 9. — Taylor 2002: 70, pl. 9, fig. 9.

non Rhagasostoma inelegans – Brydone 1930 pars: 47, pl. 25, figs 11–12.

non Rhagasostoma inelegans var. angliae – Brydone 1936 pars: 74, pl. 35, figs 4–7.

Material studied

Lectotype (here designated)

UNITED KINGDOM • England ; Chalk (?Santonian) of Sussex; NHMUK D2967 About NHMUK ( Fig. 3 A–C; figured by Lonsdale 1850: pl. 18.B, fig. 9).

Paralectotype (here designated)

UNITED KINGDOM • same data as for lectotype; NHMUK D2959 About NHMUK ( Fig. 3D; figured by Lonsdale 1850: pl. 18.B, fig. 11) .

Additional figured material

UNITED KINGDOM • England, Sussex coast; late Santonian ( Marsupites testudinarius Zone ); SM B36881 View Materials ( Fig. 3 E–G; figured by Brydone 1936: pl. 35, fig. 8) • England, Hampshire, near Winchester, Owslebury , Hensting Farm ; early Campanian ( Goniotheutis quadrata Zone ); SM B36669 View Materials ( Fig. 3 H–J; figured by Brydone 1930: pl. 26, figs 2–3) .

GERMANY • Lower Saxony, Sehnde-Höver, Alemannia quarry; early Campanian ; SMF 24564 View Materials ( Fig. 4 A–B; figured by Voigt 1975: pl. 5, figs 1, 3–4 as coll. Voigt no. 7381) • Same data as for preceding; SMF 29915 View Materials ( Fig. 4C) .

BELARUS • 2 specs; Grodno Region, quarry near Hrodna / Grodno (Гродна/ Гродно); erratic block of?late Campanian age; PIN 2922 View Materials /219 ( Fig. 4D), 2922/273 ( Fig. 4 E–F) .

Other material

GERMANY • Lower Saxony, Sehnde-Höver, Alemannia quarry; early Campanian ; SMF 29916 View Materials .

BELARUS • 2 specs; Grodno Region, quarry near Hrodna / Grodno (Гродна/ Гродно); erratic block of?late Campanian age; PIN 2922 View Materials /217, 2922/250 Description

Colony usually erect, with flattened bifoliate branches, fragments 2.0–7.0 mm long by 2.5–5.5 mm wide; encrusting sheet-like colonies, measuring up to 5.0–7.0 mm long by 3.5–7.0 mm wide. Ancestrula and early astogeny not observed. Autozooids variable in shape, often broad, 6-sided and rhomboidal with rounded distal ends, zooidal boundaries raised. Gymnocyst lacking. Cryptocyst extensive, finely pustulose, depressed or slightly convex centrally, sometimes with proximal or proximolateral peripheral caverns, up to 0.17 mm long ( Fig. 3 D–G; and Taylor 1991, 2002). Opesiae terminal, rarely subterminal, semielliptical with narrow shelf in the distal part, formed by two walls, a thin inner wall delimiting the distolateral part and a salient, thickened outer wall delimiting the proximolateral part ( Fig. 3J). Proximal edge of opesia straight, smooth, thickened, with outgrowths near the two proximolateral corners delimiting, small round opesiules (outgrowths are often broken, thus giving the opesiules the appearance of opesiular indentations or they may be obscured by sediment infills of the opesia). Septula not observed. Ovicells endozooidal, brooding cavity located within the proximal part of the distal zooid ( Figs 3C, I, 4A– D); 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. Avicularia interzooidal, longer than autozooids, elongate ( Figs 3C, I–J, 4F). Rostrum channelled, with elevated wing-like walls and pointed apex, conical in outline, asymmetrical, dextral or sinistral. Proximal part rounded, shorter and wider than rostrum. Cryptocyst pustulose, concave, sometimes with proximal peripheral caverns ( Fig. 3E). Opesia large, usually roundish, rarely oval, with thickened distolateral edge and with thin articular ridges bearing two short teeth in the proximal margin and a slitlike opesiular indentation between the teeth; opesiules lacking. Kenozooids round, located at edges of colonies ( Fig. 4A, C–D). Cryptocyst finely pustulose, peripheral caverns not observed. Opesia roundish, small. Intramural reparative budding of autozooids and avicularia sometimes observed ( Fig. 4C, F), all with the same polarity as the host zooid. Closure plates and reparative budding kenozooids not observed.

Remarks

We have restudied Lonsdale’s syntypes in the NHMUK collection, choosing a lectotype (the bifoliate specimen figured by Lonsdale 1850: pl. 18.B, fig. 9), as well as material from the collections of R.M. Brydone, E. Voigt, and T.A. Favorskaya. One specimen identified by Brydone as O. inelegans ( Brydone 1930: pl. 26, figs 2, 3) does indeed belong to this species, while another ( Brydone 1930: pl. 25, figs 11, 12) is regarded as a new species, Rhagasostoma brydonei sp. nov. The specimen figured by Brydone (1930: pl. 26, fig. 1) was not restudied. The specimen described by Brydone (1936: pl. 35, fig. 8) as belonging to the subspecies O. inelegans angliae ( Brydone, 1936) is conspecific with Lonsdale’s encrusting sheet-like colony of R. inelegans . Favorskaya (1992, 1996) mentioned three specimens of this species from Campanian deposits in Uzbekistan and Turkmenistan, which according to our studies comprise two species: R. aralense sp. nov. ( Favorskaya 1992: 125, pl. 64, fig. 6, pl. 65, fig. 1) and R. operculatum sp. nov. ( Favorskaya 1992: pl. 64, fig. 7; 1996: pl. 3, fig. 4).

Rhagasostoma inelegans can be easily distinguished from R. brydonei sp. nov., R. minuens Brydone, 1936 and R. operculatum sp. nov. in having an avicularian rostrum conical in outline rather than spade-shaped or falciform. It further differs from R. brydonei sp. nov. by having endozooidal ovicells instead of immersed ovicells. Rhagasostoma inelegans differs from R. angliae in that the avicularian cryptocyst has a large roundish or oval opesia lacking opesiules, instead of a small subcircular opesia with two opesiules. It differs from R. aralense sp. nov., which also has an avicularian rostrum conical in outline, by the rostrum being asymmetrical instead of symmetrical, and the avicularian opesia roundish rather than egg-shaped.

Distribution

Late Santonian United Kingdom: Coast of Sussex, England. Early Campanian Germany: Alemannia quarry, Sehnde-Höver, Lower Saxony; Lahstedt-Oberg, Lower Saxony (according to Voigt 1949, 1975).

United Kingdom: Hensting Farm, Owslebury, Hampshire, England. Late Campanian Belarus: Quarry near Hrodna / Grodno (Гродна/ Гродно), Grodno Region.

References

Brydone R. M. 1930. Further Notes on New or Imperfectly Known Chalk Polyzoa. Part II. (Vincularia, Onychocella, Rhagasostoma, Porina, etc.). Dulau and Co., London.

Brydone R. M. 1936. Further Notes on New or Imperfectly Known Chalk Polyzoa. Part III. (Semieschara, Micropora, Cryptostoma, etc.). Dulau and Co., London.

Favorskaya T. A. 1992. Мsaнki kaмpaнa i мaaсtрikta Юga СССР [Campanian and Maastrichtian bryozoans of the southern USSR]. In: Okuneva T. M., Titova M. V., Favorskaya T. A., Zonova T. D. & Rostovtsev K. O. (eds) Atlas rukovodyashchikh grupp fauny mesozoya Yuga i Vostoka SSSR. Trudy Vserossiyskogo Nauchno-issledovatelskogo Geologicheskogo Instituta, new series 350: 115 - 136. Nedra, St Petersburg.

Favorskaya T. A. 1996. Pрakticiсkoi рukovodсtvo po мakрoфauнi Рoссii i сopрidiльныk tiррitoрiй [A Practical Handbook on the Macrofauna of Russia and Adjacent Territories: Bryozoans of the Mesocenozoic]. Oleynikov A. N. (ed). Ministerstvo prirodnich resursov RF i Vserossiyskiy Nauchno-issledovatelskiy Geologicheskiy Institut, St Petersburg.

Lonsdale W. 1850. Description of the fossils of the Chalk Formation. Note on the corals. In: Dixon F. (ed) The Geology and Fossils of the Tertiary and Cretaceous Formations of Sussex: 237 - 324. Longman, Brighton.

Taylor P. D. 1991. Bryozoen. In: Owen E. & Smith A. B. (eds) Kreide-Fossilien: ein Bestimmungsatlas der Fossilien des Chalk: 27 - 37. Goldschneck-Verlag, Korb.

Taylor P. D. 2002. Bryozoa. In: Smith A. B. & Batten D. J. (eds) Fossils of the Chalk. 2 nd edition: 53 - 75. Palaeontological Association, London.

Voigt E. 1949. Cheilostome Bryozoen aus der Quadratenkreide Nordwestdeutschlands. Mitteilungen aus dem Geologischen Staatsinstitut in Hamburg 19: 1 - 49.

Voigt E. 1975. Bryozoen aus dem Campan von Misburg bei Hannover. Berichte der Naturhistorischen Gesellschaft Hannover 119: 235 - 277.

Tables

Table 1. Summary of measurements of Rhagasostoma inelegans (Lonsdale, 1850). 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 Late Santonian to early Campanian Sussex, Hampshire	North German Basin Early Campanian L. Saxony	Polish Basin?Late Campanian Grodno Region	Total
	AzL	300–600 (24) 475.42 ± 59.71	510–830 (12) 630.83 ± 97.56	470–580 (17) 520.59 ± 35.44	300–830 (53) 525.09 ± 87.76
	AzW	270–480 (24) 356.67 ± 54.75	410–620 (12) 510.00 ± 73.61	340–470 (16) 390.63 ± 37.50	270–620 (52) 402.50 ± 81.77
Autozooids	Avicularia	Kenozooids	CvL OpL OpW 40–170 (12) 94.17 ± 37.77 140–190 (24) 157.92 ± 12.15 150–220 (24) 174.58 ± 20.21 Not observed 160–250 (12) 150–220 (14) 199.17 ± 25.03 187.14 ± 18.16 190–290 (12) 160–210 (14) 222.50 ± 27.01 190.71 ± 12.69 40–170 (12) 94.17 ± 37.77 140–250 (50) 176.00 ± 24.99 150–290 (50) 190.60 ± 27.80 OoL 170–240 (11) 195.45 ± 24.23 240–290 (5) 268.00 ± 21.68 280–330 (3) 306.67 ± 25.17 170–330 (19) 232.11 ± 51.05 OoW 200–240 (12) 219.17 ± 14.43 230–280 (5) 260.00 ± 24.60 200–260 (3) 226.67 ± 30.55 200–280 (20) 230.50 ± 24.60 AvL 520–740 (23) 659.57 ± 54.89 660–1190 (12) 884.17 ± 169.46 720–860 (9) 768.89 ± 50.36 520–1190 (44) 743.18 ± 137.06 RL 320–430 (23) 390.43 ± 31.11 340–680 (12) 527.50 ± 105.75 440–580 (9) 480.00 ± 43.87 320–680 (44) 446.14 ± 86.38 Avicularia RW PrL PrW 110–190 (23) 143.04 ± 18.45 180–320 (24) 253.33 ± 31.30 170–250 (23) 212.17 ± 22.55 140–290 (12) 195.00 ± 44.21 270–550 (12) 361.25 ± 105.79 220–360 (12) 267.50 ± 42.88 130–180 (9) 151.11 ± 19.00 230–320 (10) 261.00 ± 26.01 210–280 (9) 232.22 ± 24.38 110–290 (44) 158.86 ± 35.39 180–550 (46) 283.15 ± 74.71 170–360 (44) 231.36 ± 37.45 OpL 60–140 (14) 101.43 ± 29.58 90–220 (10) 140.00 ± 40.00 80–130 (8) 108.75 ± 15.53 60–220 (32) 115.31 ± 34.36 OpW 70–130 (14) 91.43 ± 19.16 60–195 (10) 115.50 ± 48.79 90–120 (8) 102.50 ± 10.35 70–195 (32) 101.72 ± 31.28 Kenozooids KzL KzW OpD Not observed 290–740 (6) 500.00 ± 159.00 160–370 (6) 296.33 ± 83.80 60–120 (6) 85.00 ± 25.10 340–400 (4) 372.50 ± 27.54 360–400 (4) 377.50 ± 20.62 140–180 (4) 157.50 ± 17.08 290–740 (10) 449.00 ± 136.50 160–400 (10) 328.80 ± 76.16 60–180 (10) 114.00 ± 43.00	OoL	OoW	AvL	RL	RW PrL PrW	OpL	OpW	KzL KzW OpD Not observed 290–740 (6) 500.00 ± 159.00 160–370 (6) 296.33 ± 83.80 60–120 (6) 85.00 ± 25.10 340–400 (4) 372.50 ± 27.54 360–400 (4) 377.50 ± 20.62 140–180 (4) 157.50 ± 17.08 290–740 (10) 449.00 ± 136.50 160–400 (10) 328.80 ± 76.16 60–180 (10) 114.00 ± 43.00	40–170 (12) 94.17 ± 37.77 140–190 (24) 157.92 ± 12.15 150–220 (24) 174.58 ± 20.21	170–240 (11) 195.45 ± 24.23	200–240 (12) 219.17 ± 14.43	520–740 (23) 659.57 ± 54.89	320–430 (23) 390.43 ± 31.11	110–190 (23) 143.04 ± 18.45 180–320 (24) 253.33 ± 31.30 170–250 (23) 212.17 ± 22.55	60–140 (14) 101.43 ± 29.58	70–130 (14) 91.43 ± 19.16	Not observed	Not observed 160–250 (12) 150–220 (14) 199.17 ± 25.03 187.14 ± 18.16 190–290 (12) 160–210 (14) 222.50 ± 27.01 190.71 ± 12.69	240–290 (5) 268.00 ± 21.68	230–280 (5) 260.00 ± 24.60	660–1190 (12) 884.17 ± 169.46	340–680 (12) 527.50 ± 105.75	140–290 (12) 195.00 ± 44.21 270–550 (12) 361.25 ± 105.79 220–360 (12) 267.50 ± 42.88	90–220 (10) 140.00 ± 40.00	60–195 (10) 115.50 ± 48.79	290–740 (6) 500.00 ± 159.00 160–370 (6) 296.33 ± 83.80 60–120 (6) 85.00 ± 25.10	280–330 (3) 306.67 ± 25.17	200–260 (3) 226.67 ± 30.55	720–860 (9) 768.89 ± 50.36	440–580 (9) 480.00 ± 43.87	130–180 (9) 151.11 ± 19.00 230–320 (10) 261.00 ± 26.01 210–280 (9) 232.22 ± 24.38	80–130 (8) 108.75 ± 15.53	90–120 (8) 102.50 ± 10.35	340–400 (4) 372.50 ± 27.54 360–400 (4) 377.50 ± 20.62 140–180 (4) 157.50 ± 17.08	40–170 (12) 94.17 ± 37.77 140–250 (50) 176.00 ± 24.99 150–290 (50) 190.60 ± 27.80	170–330 (19) 232.11 ± 51.05	200–280 (20) 230.50 ± 24.60	520–1190 (44) 743.18 ± 137.06	320–680 (44) 446.14 ± 86.38	110–290 (44) 158.86 ± 35.39 180–550 (46) 283.15 ± 74.71 170–360 (44) 231.36 ± 37.45	60–220 (32) 115.31 ± 34.36	70–195 (32) 101.72 ± 31.28	290–740 (10) 449.00 ± 136.50 160–400 (10) 328.80 ± 76.16 60–180 (10) 114.00 ± 43.00
	OoL	170–240 (11) 195.45 ± 24.23	240–290 (5) 268.00 ± 21.68	280–330 (3) 306.67 ± 25.17	170–330 (19) 232.11 ± 51.05
	OoW	200–240 (12) 219.17 ± 14.43	230–280 (5) 260.00 ± 24.60	200–260 (3) 226.67 ± 30.55	200–280 (20) 230.50 ± 24.60
	AvL	520–740 (23) 659.57 ± 54.89	660–1190 (12) 884.17 ± 169.46	720–860 (9) 768.89 ± 50.36	520–1190 (44) 743.18 ± 137.06
	RL	320–430 (23) 390.43 ± 31.11	340–680 (12) 527.50 ± 105.75	440–580 (9) 480.00 ± 43.87	320–680 (44) 446.14 ± 86.38
Avicularia	RW PrL PrW	110–190 (23) 143.04 ± 18.45 180–320 (24) 253.33 ± 31.30 170–250 (23) 212.17 ± 22.55	140–290 (12) 195.00 ± 44.21 270–550 (12) 361.25 ± 105.79 220–360 (12) 267.50 ± 42.88	130–180 (9) 151.11 ± 19.00 230–320 (10) 261.00 ± 26.01 210–280 (9) 232.22 ± 24.38	110–290 (44) 158.86 ± 35.39 180–550 (46) 283.15 ± 74.71 170–360 (44) 231.36 ± 37.45
	OpL	60–140 (14) 101.43 ± 29.58	90–220 (10) 140.00 ± 40.00	80–130 (8) 108.75 ± 15.53	60–220 (32) 115.31 ± 34.36
	OpW	70–130 (14) 91.43 ± 19.16	60–195 (10) 115.50 ± 48.79	90–120 (8) 102.50 ± 10.35	70–195 (32) 101.72 ± 31.28
Kenozooids	KzL KzW OpD Not observed 290–740 (6) 500.00 ± 159.00 160–370 (6) 296.33 ± 83.80 60–120 (6) 85.00 ± 25.10 340–400 (4) 372.50 ± 27.54 360–400 (4) 377.50 ± 20.62 140–180 (4) 157.50 ± 17.08 290–740 (10) 449.00 ± 136.50 160–400 (10) 328.80 ± 76.16 60–180 (10) 114.00 ± 43.00	Not observed	290–740 (6) 500.00 ± 159.00 160–370 (6) 296.33 ± 83.80 60–120 (6) 85.00 ± 25.10	340–400 (4) 372.50 ± 27.54 360–400 (4) 377.50 ± 20.62 140–180 (4) 157.50 ± 17.08	290–740 (10) 449.00 ± 136.50 160–400 (10) 328.80 ± 76.16 60–180 (10) 114.00 ± 43.00