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XXX.—The BritishSpecies of Scruparia(Polyzoa)Anna B. Hastings M.A., Ph.D. aa British Museum (Natural History)Published online: 20 Feb 2012.

To cite this article: Anna B. Hastings M.A., Ph.D. (1941)XXX.—The British Species of Scruparia (Polyzoa), Annals andMagazine of Natural History: Series 11, 7:41, 465-472, DOI:10.1080/03745481.1941.9727946

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On the British Species of Scruparia. 465

XXX.-The British Species of Scruparia (Polyzm). By ANNA B. HASTINGS, M.A., Ph.D., British Museum (Natural History).

THE genotype of Scruparia Oken (1815) was established by Harmer (1923, p. 316). Hitherto there has been supposed to be one British species, S. chelata (Linn.), with some not very clearly defined varieties. While considering some specimens of the genus, brought from the Patagonian region by the ‘ Discovery ’ Expedition, I re-examined the supposed material of S. chelata in the British Museum and found that it comprised two well- marked species, both widely distributed, and both found in Britain.

Typical S. chelata has relatively large horn-shaped zocecia, and the erect branches arise from creeping stolons (fig. 1, A). The ovicells are large and are nearly as long as the fertile zocecia, whose opesia is broader than long (fig. 2, C). The other species, which I recognize as S. ambigua (d’Orb.), see below, is more delicate, and has zocecia arising from encrusting zocecia instead of from stolons (fig. 1, B). The opesia of the non-fertile zocecia is longer and is parallel to the basal wall of the zocecium, instead of dipping obliquely towards the distal end. The ovicell is not only absolutely smaller than that of typical S. chelata, but also smaller relatively to the fertile zocecium (fig. 2, A, B). The opesia of the fertile zocecium is longer than wide. The encrusting zocecia of S. ambigua may give rise to buds distally, frontally and on each side. All the buds form zoecia, the frontal one being erect and the others encrusting. The encrusting stolons of S. chelata form more or less distinct swellings at intervals which have already been recognized as probably the morphological equivalent of zocecia (Hincks, 1880, p. 13). Each swelling may give rise to buds distally, frontally and on each side. The frontal one forms erect zocecia, the lateral ones encrusting rootlets, an arrangement exactly comparable to that just described in X. ambigua.

The two species are mixed on the same weed, hydroids etc., in the Museum’s British material, but are clearly recognizable, even without ovicells, when once the

Ann. & Maq. N . Hist. Ser. 11. VoZ. vii, 31

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466 Dr. Anna B. Hastings on

difference in the shape and size of the zoecia and the nature of the encrusting part has been noticed.

Himcks's figure (1880, pl. ii. fig. 4) of horn-shaped zoecia springing from an apparently encrusting series of similar

Fig. 1.

A. Sciuparia chelata (Linn.). SouthDevon. Hincks Coll. 99.5.1.3118 Showing ancestrula, creeping stolons, and erect branches.

B, C. Sowparia ambigua ($Orb.). Tagus Cove, Galapagos. 29.4.26.15. B. Showing ancestrula, creeping and erect zocecia, and a fertile

C. Ancestrula and fh t two zocecia on meed. zocecium.

The substratum around the encrusting parts is indicated by hatching.

n., ancestrula ; op., operculum.

zoecia appears to invalidate the distinction recognized here, but is, I think, erroneous. On drying, the erect branches of S. cheZutu commonly come to lie in just this way, as could be seen in Hincks's own pecimens, but

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the British Species of Scruparia. 467

I .have seen no specimen where any zocecia of this type are truly encrusting.

Gosse (1853), who gives a vivid account of his observa- tions on 8. chehta (pp. 132-139)) shows the characteristic stolon in one of his figures (pl. vi. fig. 2)) and it is also

Fig. 2.

0

A, - i B. Scruparia ambiyua (d’Orb.). Tagus Cove, Galapagos. 29.4.26.15.

Fertile zocecia in lateral and frontal view. In A the encrusting zocecia from which the fertile zoceciurn arises are shown. Substratum hatched.

C. Scruparia c ldata (Linn.). Roscoff. 22.8.1.3. Fertile zocecium on an erect zocecium drawn in the same position a8

clw., distal wall of zocecium ; kZ., keel ; ops., opesia. A for comparison.

shown in the original figure of the species (Ellis, 1755, pl. xxii. fig. B).

I have no doubt that the more delicate species is the form forwhich Hincks (1880) proposed the name Eucratea chelata var. yracilis, but there is no British specimen of the more delicate species in the Hincks Collection *) nor any specimen labelled as belonging to the variety. Hincks’s Australian material of supposed E. chelata is represented by two slides each with very few zocecia.

* At the time when this revision of the British material was done, onc slide of 8. cheltsta from the Hineks Collection (99.7.1.588) was stored for the war and could not be examined.

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468 Dr. Anna B. Hastings on

one labelled “ normal form,” the other “ slender form,” but both belong to the more delicate species. I have seen no specimen of typical S. chelata from Australia, but there is material of both species from New Zealand.

It is probable, however, that S. chlatu var. gracilis as here understood, is a synonym of S. ambigua (d’Orb., 1841). D’Orbigny’s species came from the Falkland Islands (fles Malouines),which is one of thelocalities of var. graciZis, D’Orbigny’s figures agree with var. gracilis in the shape and general proportions of both fertile and non- fertile zocecia. They show neither the keel nor the aper- ture of the ovicell, nor the opesia of the fertile zocecium, but the absence of any opening is evidence that the fertile zocecia are not drawn accurately. The dimensions of d’orbigny’s specimens are not known, and there is no indication of the nature of the encrusting part, but,in view of the agreement in locality and general shape and proportion, the identifkation seems very probable.

The specimens from the Galapagos Islands recorded as S. chehtu (Hastings, 1930) have ovicells and belong to S. ambigua as understood here. Similar colonies, without ovicells, have been obtained from Norway, California, Australia, Tasmania, New Zealand, theFalkland Islands, and the coast of Patagonia. The erect zoaxia of the Californian form figured by Robertson (1905, pl. v. fig. 8) agree closely with S. ambigua, and the encrusting zocecia are described. Ovicells were not found ; pl. v. fig. 9, showing an ovicell, is “ after Hincks,” and represents true X. chela&.

Hasenbank (1932, p. 325, text-fig. 1) gave characteristic figures of the non-fertile zocecia of 8. ambigua (as Eucrutea chelata) from Amsterdam Is. He mentioned several of the important differences, notably the encrusting zocecia and the fact that the erect zocecia are not horn- shaped, and compared it to the varieties gracilis and repens of Hincks.

Smitt’s figures (1867, pl. xvi. figs. 7-9) resemble X. ambigua rather than S. chelatu, and his statement (p. 301) that buds may be formed at the right and left of the zocecia, as well as distally and frontally, but that these lateral buds are only found on the creeping part of the stock, implies that the creeping part was composed of zocecia. In some of the figured zoecia the opesia is rather short, although parallel to the basal wall.

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the British Species of Scruparia. 469

The encrusting form described by Hincks as var. repens closely resembles the encrusting base of a colony of S. ambigua. The frequent presence of the little stalk-like projections proximal to the orifice suggests that erect zocecia may once have been present, and one such zocecium remains in a specimen from the Adriatic identified by Hincks with var. repem. This erect zocecium has the form of those of S. ambigua. The variety is certainly allied to S. ambigua rather than to S. chelata;, and I doubt very much whether it should be maintained.

The fertile zocecia of S. ambigua may arise directly from the encrusting zocecia as in fig. 2, A, or from erect branches, as in fig. 1, B. The ovicells of both S. chelafa and S. ambigua have a membranous ectocecium, a cal- careous entocecium and a conspicuous median keel, seen as a projecting flange in side view (lightly stippled in fig. 2, A, C ) . A side view also shows the origin of the ovicell from a quadrilateral area on the shoulder of the fertile zocecium. The appearance of the ovicell suggests that it may be of the two-valved type (see Harmer, 1926, p. 189). In this connection it is interesting to find that the ovicells of S. chelata, like the two-valved ones of Thahmoporella, may contain several embryos. As many as seven have been counted in a single ovicell in material from ROSCOE (B.M. 22.8.1.3). Only empty ovicells are to be found in the material of S. ambigua.

The material from Roscoff (fig. 2, C) has zocecia with the tubular part long and the opesia rather short, and represents the form described as var. elongata by Lomas (1886, p. 165). Such colonies have a distinctly different appearance, but the variation among the individual zocecia of both the typical form and the varietymakes ine doubt whether they should be distinguished. Lomas figures an almost circular opesia, but the outline of the zocecia of his specimen, which has become decalcified while fixed in a mount of glycerine jelly, suggests that the drawing is inaccurate, and that var. elongata really has an oval opesia like that of the other elongate specimens in the British Museum.

Ancestrulae are present in material of S. ambigua from Britain, the Patagonian coast and the Galapagos Islands, and are very numerous in the latter. Even at this early stage the two species are clearly distinguishable. In both the ancestrula is attached only by the structures

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budded from it. In the ancestrula of S. chelata (fig. 1, X the distal bud forms a rootlet which promptly attaches itself to the substratum and forms the creeping base of the colony. The ancestrula also produces a frontal and a proximal bud, each of which gives rise to an erect series of zocecia. The proximal bud faces in the opposite direction from the ancestrula, and this appearance of reversal clearly distinguishes an ancestrula from a zocecium which has formed a distal rootlet, as they occasionally do.

In S. ambigua (figs. 1, B:C) the distal bud likewise forms the creeping base of the colony, but it takes the form of a zocecium and gives rise to a series of zocecia. There is no proximal bud, and the frontal bud, like the distal bud, forms an encrusting zocecium leading to a series of encrusting zocecia from which erect branches arise. The ancestrula of S. ambigua lies on its side. that of S, chelata may be described as standing on its head.

The figured ancestrula of S. chhelala (fig. 1, A) is one of several in Hincks’s material from S. Devon. They were. however, mounted in a confused state on crumpled seaweed: and it was not until they had been cleaned and disentangled that their characteristic structure could be made out. This may account for the puzzling appearance of Hincks’s figures which are: perhaps. not quite accurate. It seems likely that, in pl. ii., figs. 6. 7 and 8 represent S. ambigua, and fig. 5 S. chelata. The erect zocecia in fig. 5 are certainly those of S. cltelata, but, as in S. ambigtux, the first zocecium is encrusting and the ancestrula has no proximal bud.

It is likely that some of the other published records of S. chelata are based on S. ambigzm, and i t is thus not possible to give a full statement of the synonymy and distribution of either species. I am therefore giving statements of the synonymy and distribution of S. ambigua, as far as I have been able to establish them, and a list of the specimens of true S. chelata in the British Museum.

Synonymy of Scruparia ambigua (d’Orb.). Eucratecl ambigua d’orbigny, 1841, pl. iii. figs. 13-17 ; 1847, P. 11. Catemria ambigua d’Orbigny, 1851, P. 43. Eucratea chelata Robertson, 1905, p. 24% PI. v. figs. 7, 8 ; Vallentin,

1924, p. 373 ; Hasenbad, 193% p. 325, text-fig. 1 (not Ser#uZu& chehta Linn.).

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the British Species of Scruparia. 47 1

Smupuria chelata Hastings, 1930, p. 702. Ewotea chelata vm. /I yracilin Hincls, 1880, p. 14 ; Lomas, 1886,

? E w u h chelata var. a repens Hincks, 1880, p. 14, pl. i. fig. 3. ? Eucralea chelrsta Smitt, 1867, pp. 281, 301, pl. svi. figs. 7-9.

p. 165.

Distribution of Scruparia ambigua (d’Ol.6.). Specimens with ovice1l.s.-Devonshire (1 1.10.1.256, Nor-

man a l l . , with S. chelata) ; Bantry Bay, Ireland (1940.11.6.1, with S. chelata) ; Gouliot Caves, Sark (1940.11.4.1, Norman Coll., with S. chelata, 12.12.21.800) ; Galapagos Islands (Hastings ; 29.4.26.15, 16) ; Falkland Islands (d’orbigny).

Specimens without ovice1l.s.-Britain (99.7.1.590, Busk Coll. ; 15.4.2.8, Norman Coll., both with S. chelata) ; Aberdaron Bay, N. Wales (1940.11.10.1, collected by Dr. F. C. Fraser and Mr. D. D. John, with S. chelata) ; Flora, Norway (12.12.21.803, Norman Coll.) ; Sweden I (Smitt) ; California (Robertson ; 1938.11.30.6, from Dr. A. Blagg) : Falkland Islands (35.3.6.29, Vallentin Coll.) ; coast of Patagonia (‘ Discovery ’ Investigations, Stations 1902, W.S.95, W.S. 847) ; Cape Horn (‘ Discovery’ Investigations, Station 222) ; Amsterdam Is., Indian Ocean (Hasenbank) ; Australia (99.5.1.320, 321) ; Port Phillip Heads (97.5.1.147-149, 152 ; 85.11.14.443) ; QueensclifFc Jetty, Port Phillip ( Discovery ’ Investiga- tions, Station 1686) ; Adelaide (99.7.1.591, Busk Coll.) ; Tasmania (99.7.1.592, Busk Coll.) ; Kew Zealand (27.8.4.1, with 8. chelatu ; Terra N0.i.a Exp. Station 134).

As vas. repens.-On shell, locality unspecified, pre- sumably Isle of Man (99.5.1.417, Hincks Coll.) ; Adriatic (99.5 1.41 6. Hincks Coll.).

Specimens of Scruparia chelata (L inn . ) in tlhe Rsitish Museum.

Specimens urith ovice1l.s.-Penzance (99.7.1.587, 589, Busk Coll.).

Specimens uvithout ovice1ls.-Britain (99.7.1.590, Busk Coll., with S. ambiguu ; 99.7.1.5753, Busk Coll.) ; Hastings (1940.11.8.1, Bowerbank Coll.) : Weymouth (99.7.1.586, Busk Coll.) ; S. Devon (99.5.1.317, Hincks Coll.) ; nevon (11.10.1.256, Korman Coll., with S. ambigua) ; Tenby (97.5.1.150) ; Aberdaron Bay, N. Wales (1940.11.10.1, collected by Dr. F. C. Fraser and Mr. D. D. John, with S. ambigua) ; Liverpool (27.6.29.3) ; Rirterbuy Bay,

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472 On the British Species of Scruparia.

Ireland (12.12.21.802, Norman Coll.) ; Bantry Baj- Ireland (1940.11.6.1, with 8. ambigua ; 1940.11.6.5) Whitby (99.7.1.585, Busk Coll.) ; Filey (34.10.24.9) New Zealand (27.8.4.11, with S. ambigua) ; localit: unknown (11.10.1.255, Norman Coll., from Mr. Barlee).

Ebngata-type. Specimens with ovice1ls.-Roscoff (22.1.8.3, three slides

mounted by Sir Sidney Harmer). Specimens without ovice1l.s.-Isle of Man (86.1.9.7.

Lomas Coll.) ; Raasay, Inverness-shire (1938.10.28.2. King’s College Newcastle Expedition) ; Gouliot Caves. Sark (12.12.21.800, Norman Coll., with S. ambigua. 1940.11.4.1).

The specimen from the Tizard Bank, recorded br Kirkpatrick (1890, p. 16) as E . chelata, consists of very few zoaxia, but appears to be related to Byettia tropica Waters (1913, p. 465) rather than to S. chelatu.

REFERENCES. ELLIS, J. 1755. ‘ An Essay towards a Natural History of the Coral-

lines.’ Pp. xvii [XI, 1903, 39 pls. London. GOSSE, P. H. 1853. ‘ A Naturalist’s Rambles on the Devonshire

Coast. Pp. xvi, ‘ 9 1 , 28 pls. London: Van der Voorst. H A R ~ R , S. F. 1923. On Cellularine and other Polyzoa.” J. Linu.

SOC. London, xxxv. pp. 293-361, 4 pls. HARMER, S. F. 1926. “ Cheilostomata Anasca.” Rep. ‘ Siboga’ Exp.

xxviii b. HASENBANC, W. 1932. ‘ I Bryozoa der Deutschen Tiefsee Expedition.”

I Teil. Wiss. Ergebn. Deutsch. Tiefsee-Exped. xxi. 2, pp. 319- 380, 1 pl., 35 text-figs.

HASTINGS, A. B. 1930. ‘‘ Cheilostomatous Polyzoa from the Vicinity of the Panama Canal . . . ” Proc. Zool. SOC. London, 1929. 4, pp. 697-740, !7 pls.

HINCKS, T. 1880. A History of the British Marine Polyzoa.’ London.

L o u , J. 1886. “ Report on the Polyzoa of the L.M.B.C. District.” Proc. Lit. Phil. SOC. Liverp. XI., Appendix, pp. 161-200, 1 pl.

KIRKPATRICK, R. 1890 b. “ Report upon the Hydrozoa and Polyzoa collected . . . in the China Sea.” Ann. &; Mag. Nat. Hist. 6,

D’ORBIGNY, A. 1841-1847. ‘‘ Zoophytes.” Voy. 1’AmBr. MBrid. v. pt. iv. pp. 7-28 (18??), Atlas ix, pl. iii. (1841).

D’ORBIGNY, A. 1850-1854. Pal6ontologie Franyaise.” Terr. CrBt. v. ROBERTSON, A. 1905. “Non-incrusting Chilostomatous Bryozoa

of the West Coast of North America. Univ. Calif. Pub., Zool. ii. 5, pp. 235-322, 13 pk;

Smm, F. A. 1867. Kritisk Forteckning ofer Skandinaviens Hafsbryozoer 111.” (Efvers’K. Vet. Akad. Forhandl. Arg. 24, no. 5, pp. 279-429, 5 pls.

1913. I‘ The Marine Fauna of p t i sh East Africa and Zanzibar . . . Bryozoa-Cheilostomata. Roc. 2001, SOC. London, pp. 468-537, 10 pls.

V. pp. 11-24, 3 pls.

WATERS, A. W.

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