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The Extant Scleractinian Corals of New Zealand

Family Flabellidae Bourne, 1905 — Genus Flabellum Lesson, 1831

Family Flabellidae Bourne, 1905

Genus Flabellum Lesson, 1831

Flabellum deludens von Marenzeller, 1904. Pl. IV, figs. 7 and 8. Map symbol ╪
1904. Flabellum deludens von Marenzeller. p. 269, Pl. 17, fig. 10.

The corallum of this species is distinguished by its deeply lacerate calicular margin formed by the highly exsert septa between which the epitheca dips downward. The epitheca uniting the upper margins of the septa is a glistening white, while that on the lower portions of the corallum is much darker. Five cycles of septa are present, but are not complete in all systems. The columella is simple, formed of the union of the first and second cycles of septa in the centre of the calice with some trabecular curls developed above this union.

Three coralla taken off Palliser Bay are 25 mm, 35 mm, and 36 mm in height, and are quite typical in all respects for the species, showing the prominent proximal ends of the septa between which the epitheca is concave inwards so as to form a scalloped side wall. The septa of these corals is finely ridged, not conspiciously granulate.

Squires (1958) grouped the Indo-Pacific species of Flabellum having lacerate septal margins, recognising F. apertum, F. deludens and F. japonicum. F. apertum is distinguished by, among other characters, possession of only four cycles of septa. F. deludens and F. japonicum are close, but distinguished by the more solid construction of the latter, and the greater development of columellar trabeculae. The specimens from Palliser Bay show an interesting intermediate development in this respect. Most important in distinguishing between F. deludens and F. japonicum is the greater laceration of the upper margin in the former.

The distinction between the several species confused with F. deludens in the literature has been discussed by von Marenzeller (1904) and more recently by Squires (1960).

Occurrence: Off Palliser Bay, 41° 33′ S., 174° 55′ E., 380 fathoms. Three specimens taken alive. (Victoria University, Zoology Department.)

Distribution: Japan, Philippine Islands, Hawaiian Islands, Indian Ocean, New Zealand.

Flabellum gracile (Studer), 1877. Pl. IV, figs. 9 and 10. Map symbol ≢
1877. Desmophyllum gracile Studer. p. 629, Pl. 1, figs. 2a, 2b.

This species is closely allied with the tall scolecoid Flabellum antarcticum (Gravier). Originally F. gracile was described from a single specimen, taken in 90 fathoms, from 34° 9.9′ S., 172° 35.8′ E., and has since been recollected only by the Discovery II. The corallum is tall, conical and very lightly constructed. The wall is formed by a glistening epitheca. Septa are very thin and relatively numerous.

The species is, apparently, not only rare, but, when found, occurs in very small numbers. It is easily distinguished from F. rubrum by its much lighter construction and its relatively smaller size.

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Occurrence: Off Three Kings Island, 90 fathoms. One specimen taken alive. (Auckland Museum, Coral Collection.)

Distribution.: New Zealand.

Flabellum rubnim Quoy and Gaimard, 1833. Pl. V, figs. 1-18; Pl. VI, figs. 1-9. Map symbol ≠
1833. Turbinolia rubra Quoy and Gaimard, p. 188, Pl. 14, figs. 3-3d.
1862. Flabellum nobile Holdsworth, p. 198, Pl. 28, figs. 4-5.
1878. Flabellum latum Studer, p. 630, Pl. 1, figs. 3a-3b.
1880. Flabellum rugulosum Tenison-Woods, p. 12, figs. 8a, b.
1929. Flabellum harmeri Gardiner, p. 122, Pl. 1.
Flabellum rubrum Squires. In Press.

The concept of this species has been so altered by broad application of the name that in its present day context, F. rubrum is little more than a catchall. Elsewhere, one of us (D.F.S.) has presented a complete review of the systematics of the species. At the present time, it is our opinion that Flabellum rubrum, as interpreted from New Zealand topotype specimens, includes, apparently, only New Zealand Flabellum. Utilisation of the species name in other areas of the Indo-Pacific and Indian Ocean is incorrect.

As most species of Flabellum are quite plastic in growth form, so is F. rubrum. Shallow water forms, found almost intertidally in various areas in the North Island, are nearly cylindrical, short coralla, firmly cemented to the bottom. Powell (1937) noted the colour of the corallum to be salmon to dull vermillion. In deeper waters of the Hauraki Gulf and Cook Strait, the coral is commonly encountered, usually with the corallum firmly cemented to another corallum, fragments or complete shells, stones, or some other hard object. Although Powell describes the animal as scarlet, those we have observed are usually orange, with yellow tentacles. Although for years the shallow water form has been called Flabellum rubrum and the deeper water form Flabellum rugulosum, it is our opinion that they are one and the same species. Independently, both authors have attempted to arrange the cylindrical growth form of the shallow water type and the pedicellate, cuneiform corallum of the deeper water form along a morphological gradient corresponding to depth. There appears to be none. The diameter of the base of the skeleton is, apparently, a function of the support required by the animal, those living in regions of greater wave or current action having the greater basal diameter. Specimens with the characters of F. harmeri and F. latum are found growing with specimens clearly of the F. rubrum type. F. latum Studer is much longer in the greatest diameter of the calice than specimens of the other species, but, since the degree of variation in this respect is considerable, there is little reason to maintain it as a distinct species.

Occurrence: Between Cuvier Island and Mokohinau Island, 50 fathoms. Two specimens taken alive. South Taranaki Bight, off Rangitikei River. No depth. Three specimens taken dead. South Taranaki Bight, 10-15 miles off Rangitikei River, 40-42 fathoms. One specimen taken alive. South Taranaki Bight. No depth. Thirty specimens. New Zealand. Intertidal. Two specimens taken alive. Hauraki Gulf, 25 fathoms. One specimen. Mercury Bay, 20 fathoms. One specimen taken alive. Off Cape Campbell, 55 fathoms. One dead and worn specimen. (Geological Survey, Coral Collection.) Gannet Island, off east end of Waiheke Island, Hauraki Gulf, 12 to 13 fathoms. Seven specimens plus young, taken alive. Off Tiri Tiri, Hauraki Gulf, 7 fathoms. Specimens taken alive. One and a half miles northeast of Leigh, Hauraki Gulf, 30 fathoms. One specimen taken alive attached to shell of Xenophora. Hen and Chicken Island, 30 fathoms. One dead specimen. North northeast of Mayor Island, Bay of Plenty, 46 to 82 fathoms. Two dead specimens, one taken alive. Off East Cape, 85 fathoms. One specimen taken alive, attached to Terebratella haurakiensis (Auckland Museum, Coral Collection.)

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North of Cuvier Island. 50 fathoms. One specimen taken alive. Karewa Island, Bay of Plenty. Shallow water. Five large specimens taken alive. Off Coromandel Peninsula, 20 fathoms. Six specimens taken alive. Between Hen and Chicken Islands. No depth. One specimen taken alive. North of Kapiti Island, Tasman Sea, 30 fathoms. Two specimens taken alive. Cook Strait, 41° 28.5′ S., 174° 50′ E., 150 fathoms. Ten specimens, all dead and possibly derived. Kapiti Channel, Tasman Sea, 40° 52.2′ S., 174° 57.3′ E., 33 fathoms. Off Mayor Island, Bay of Plenty, 37° 19.5′ S., 176° 16′ E., 60 to 100 fathoms. Two dead specimens. Ten miles west, half a mile south Cuvier Island, 32 fathoms. One specimen taken alive. Pelorus Sound, South Island, 25 to 30 fathoms. One immature specimen. Off Wellington Harbour, 41° 28.5′ S., 174° 50′ E., 150 fathoms. Three specimens taken alive, 14 specimens taken dead. Cook Strait, 40° 49.6′ S., 174° 36.8′ E., 81 fathoms. Five dead specimens. Goal Passage, Doubtful Sound, Westland, 25 fathoms. Four dead specimens associated with crinoids. Cook Strait, 40° 52.6′ S., 174° 49.5′ E., 75 fathoms. Five dead specimens. Whangamumu, Northland. Shallow water. Four live specimens. Long Beach, Bay of Islands. Shallow water. Twelve specimens taken alive (Dominion Museum, Coral Collection.)

Off Palliser Bay, 41° 42′30" S., 175° 9′ E., 550 fathoms. A fragment of a columella, probably a derived specimen. VUZ 113, Stat. CUD, Palliser Bay Shelf, 41° 35′ S., 175° 4′ E., 70-80 fathoms. Two dead and worn specimens. Between Little Barrier Island and Great Barrier Island. No depth record. One immature specimen, taken alive. Two miles south from North Cape, Northland, 55 fathoms. Twelve specimens, most taken alive. One specimen attached to a dead branch of Oculina virgosa. Off Hen and Chicken Islands, 26 to 30 fathoms. One small specimen taken alive. Cook Strait, 40 fathoms. Eleven specimens taken alive, one dead. Whangaparapara, Great Barrier Island. No depth. Two specimens mutually attached taken alive. Off Gilbert Island, Breaksea Sound, Westland, 15 fathoms. Several bases of this species. Cook Strait. No depth. Several specimens taken alive. Off Mayor Island, Bay of Plenty, 37° 20′ S., 176° 18′ E., 50-110 fathoms. One specimen taken alive. Near Leigh, Northland. Shallow water. Seven specimens taken alive. (Zoology Department, Victoria University.)

Distribution: New Zealand.

Flabellum knoxi n.sp. Pl. 7, figs 1 and 2. Map symbol ≢

Types: Figured holotype (Pl. 7, figs. 1, 2) deposited in Canterbury Museum, Christchurch.

The corallum of this new species is distinguished from all other known extant New Zealand flabellids by its large size in which the width is usually greater than the height, by its extremely thin fragile skeleton, particularly in the region of the margin of the calice and by the calicular margin forming almost a half circle. The corallum ranges in height from 35 to 70 mm and from 50 to 105 mm in width. The calice is broad and open, 23 to 45 mm wide and the septa extend almost to the centre. The septa number from 130 up to 348. Every fourth septum reaches the relatively "deep" and well formed columella. The edges of the larger septa are undulated, with the undulations most readily observed on septa reaching to the columella particularly at the junction of septum and columella. The faces of the septa are slightly ridged and finely granulated. The most conspicuous ridges and granules are found on septa reaching the columella. The angle formed by the lateral edges of the corallum is 125° to 157°. The lateral edges may have small crests. The epitheca is marked by irregular, rugose concentric growth lines. The pedicel is laterally compressed and shows an attachment scar. The flesh of the polyp was deep red (Munsell's standard colour YR 3/4.)

Flabellum knoxi, n.sp. is evidently closely related to F. magnificum von Marenzeller (1904) described from the Indian Ocean and Japan. Both are among the page 15largest known Flabellum and are quite similar in most respects, particularly the structure of the columella and of the septa. F. magnificum, however, is somewhat more costate externally than F. knoxi.

Among the suite of specimens taken by the Chatham Islands Expedition were several large deformed specimens, in which one lateral face had been reflexed upward, and the union of the lateral faces curved back upon the pedicel (Knox, 1957, fig. 6.) This deformation has been attributed to differential growth resulting from the falling over of the corallum, so that instead of the coral being erect, it lies upon one side. Roger (1944) has discussed similar growth habits among fossil specimens and speculated upon its origins (see also Squires, 1958.) A more complete description of these specimens, together with a review of the significance of their development in the evolution of similar growth forms in the fossil record, is being prepared for publication by one of us (D.F.S.).

Occurrence: Chatham Rise, 260 fathoms. 44° 04′ S., 178° 04′ E., Chatham Island Expedition, Station 52. Six specimens taken alive.

Chatham Rise, 220 fathoms. 43° 40′ S., 179° 28′ E., Chatham Island Expedition. Station 6. One specimen taken alive.

Chatham Rise, 280 fathoms. 43° 42′ S., 179° 55′ E., Chatham Island Expedition. Station 7. Three specimens taken alive (Canterbury Museum, Coral Collection.)