Descriptions of two New Zealand sea anemones (Actiniaria: Hormathiidae)

Transcription

1 New Zealand Journal of Marine and Freshwater Research ISSN: (Print) (Online) Journal homepage: Descriptions of two New Zealand sea anemones (Actiniaria: Hormathiidae) Cadet Hand To cite this article: Cadet Hand (1975) Descriptions of two New Zealand sea anemones (Actiniaria: Hormathiidae), New Zealand Journal of Marine and Freshwater Research, 9:4, , DOI: / To link to this article: Published online: 30 Mar Submit your article to this journal Article views: 153 View related articles Citing articles: 3 View citing articles Full Terms & Conditions of access and use can be found at

2 1975] 493 DESCRIPTIONS OF TWO NEW ZEALAND SEA ANEMONES (ACTINIARIA: HORMATHIIDAE) CADET HAND Bodega Marine Laboratory, P.O- Box 247, Bodega Bay, California 94923, U.S.A. and Department of Zoology, University of California, Berkeley (Received 29 August 1974; revision received 14 April 1975) ABSTRACT The sea anemones Calliactis conchicola Parry, 1952 and Paracalliactis rosea n.sp. are described. This is the first report of the hormathiid genus Paracalliactis for New Zealand. Calliactis conchicola occurs with living gastropods, hermit crabs, and a true crab, and Paracalliactis rosea occurs with hermit crabs and a true crab. Certain characteristics of each of the two anemones suggest that the genera Calliactis and Paracalliactis may not be as discrete as was indicated by earlier reports. INTRODUCTION Parry (1952, p. 127) described the acontiate hormathiid sea anemone Calliactis conchicola from New Zealand as a new species and reported its occurrence on both living and h"rmit-crab-occupied gastropod shells. The specimens she studied were obtained by commercial fisrr'ng trawlers in 80 m ("250 feet") of water on soft sandy bottoms 80 km ("50 miles") "east by northeast" of Lyttelton Harbour, and she speculated that it might be "quite possible that they are fairly widespread round the coast". This speculation has been at least partly borne out. The species is common subtidally off both Taiaroa Head, Otago, and the Kaikoura area. I have had an opportunity to examine several hundred specimens of this species from several sources. These included preserved material in the collections of both the University of Canterbury's Edward Percival Marine Laboratory and the University of Otago's Portobello Marine Laboratory. Additionally, I have examined living specimens at both Kaikoura and Portobello. During the course of my observations at Portobello I became aware that I was dealing with two species of sea anemones; one, which usually had a creamy coloured column, seems best referred to Parry's Calliactis conchicola, and one with a silvery white column that is an undescribed species of Paracalliactis, a genus unknown to date from New Zealand. As will be explained below, Parry too may have been dealing with both these species, as some parts of her description seem more apt for Paracalliactis than Calliactis. It seems advisable, therefore, to redescribe Parry's species as well as to provide a description of the new species. N.Z. Journal of Marine and Freshwater Research 9 (4) :

3 494 N.Z. JOURNAL OF MARINE & FRESHWATER RESEARCH [DEC. The following familial and generic definitions, except as modified and indicated by italics, are from Carlgren (1949). Family HORMATHIIDAE Carlgren "Thenaria (Acontiaria) with strong mesogleal sphincter. Mesenteries not divisible into macro- and microcnemes. Usually six pairs of perfect mesenteries, sometimes more, but they are never numerous. Perfect mesenteries usually sterile, rarely fertile. Nematocysts of the acontia basitrichs only. Cnidom: spirocysts, basitrichs, microbasic p-mastigophores. Usually the spirocysts are large and broad." Genus Calliactis Verrill "Hormathiidae with well developed base. Column smooth, not or only slightly differentiated into scapus (which is often provided with a weak cuticle) and scapulus, often thick, sometimes with numerous ectodermal invaginations, which do not pierce the wall. Cinclides present (always?) in the proximal part of the column. Sphincter strong, mesogleal. Tentacles usually rather short, conical; usually more numerous than the mesenteries at the base, their longitudinal muscles ectodermal. Radial muscles of the oral disc more or less embedded in the mesoglea. Two broad siphonoglyphs. Six pairs of perfect and sterile mesenteries, two pairs of directives. Retractors of mesenteries fairly weak, diffuse. Parietobasilar and basilar muscles weak or rather well developed. Often commensal with hermit crabs. Cnidom: spirocysts, basitrichs, microbasic p-mastigophores." In the generic definition given by Carlgren (1949), the tentacles are described as short and conical and more numerous than the mesenteries at the base, but in my study of live Calliactis conchicola this did not apply: the tentacles were long and slender when well expanded, and the number agreed with the number of mesenteries at the base. However, in preserved material the tentacles are short and conical, but no great significance need be attached to this. Shape per se in anemones is only marginally useful because their plastic nature allows wide variation in form. The number of tentacles in relation to the mesenteries is more important, however, and will be discussed after the detailed species description to follow. To accommodate this species in this genus, the word "usually" has been inserted in two places in the generic definition of Calliactis. Calliactis has 17 species distributed from the tropics to cold-temperate waters in both hemispheres. There are, however, no Arctic or Antarctic representatives, and the majority of the species are found in tropical or warm temperate waters. The occurrence of a species of Calliactis in the cold-temperate waters of New Zealand is paralleled by the occurrence of C. reticulata Stephenson, 1918 at 42 S in the Atlantic Ocean. There is also an Australian species, Calliactis miriam Haddon & Shackleton, 1893, which according to Parry (1952, p. 129) seems quite distinct from the New Zealand one. Calliactis conchicola Parry, 1952 is the only species known from New Zealand and is distinctive in its cnidom and colour, however. Because Parry's description is brief and only an incomplete cnidom was reported, a fuller description follows.

4 1975] HAND DESCRIPTIONS OF TWO SEA ANEMONES 495 Ectodermal pit Mesoglea FIG. 1 Camera lucida drawing of longitudinal section of upper column of Calliactis conchicola, illustrating the mesogleal sphincter, and showing ectodermal pits and cuticle of scapus. (Base of anemone on left.) Calliactis conchicola Parry, 1952, p. 127 Figs 1 & 2 Base: Circular or irregularly circular to an elongated oval in outline. Adherent to snail shells and crab carapaces and attached to the substrate by cuticular material. Usually the limbus is close to or at the lip of the snail shell and may, when a large anemone is on a small shell, somewhat overhang it. Basilar muscles are present but are weakly developed. The diameter of the base is usually about twice the diameter of the disc. Column: Divisible into scapus and scapulus. The scapus with a light brown, thin, fairly readily removable cuticle. Under the cuticle, the scapus is generally free of obvious pigment though commonly one side of the column, usually that toward the aperture of the snail shell, if on a shell, has an area coloured with brown to purple pigment. Specimens on crabs may likewise possess this curious asymmetrical dark pigment but others on crabs may have a generally purplish column or may have rather random purple patches. The column, with cuticle removed, is in the non-purple areas a pale straw to creamy colour, as is the scapulus. In an expanded animal, with cuticle intact, the scapulus is readily seen as a pale band immediately beneath the crown of tentacles. On many individuals there are faint pigmented areas in the scapulus. These occur as spidery lines, sometimes a series of V-shaped marks, which are brown, maroon, or purple in colour. On contracting, the tentacles and scapulus are completely withdrawn, and the upper part of the scapus forms a ring of small protuberances or ribs at the point of closure. These protuberances apparently have no histological identity and are not tubercles. When contracted the column assumes a hemispherical shape, and there may be well marked concentric ridges around the column. In histological preparations, cut at lo /im and stained with Mallory's Triple Stain, the distal end of the scapus is sometimes marked by a slight thickening of the ectoderm, and the beginning of the ectodermal pits (Fig. 1). These pits are very numerous and in fixed material are readily visible under low power magnification (10X) as minute, light-coloured specks. Pits occur to within a few millimetres of the limbus, where they become sparse or nonexistent in an area where the mesoglea is no thicker than the epithelium at the limbus. The epithelium of the scapulus has few gland cells, but becomes more glandular on the scapus. The mesoglea of both scapus and scapulus is thick, and is commonly more than 10 times as thick as the epithelium.

5 496 N.Z. JOURNAL OF MARINE & FRESHWATER RESEARCH [DEC. A strong mesogleal sphincter is present and occupies about two-thirds of the thickness of the mesoglea throughout the scapulus and upper scapus. In the scapulus the sphincter consists of nearly parallel lamellae of mesoglea, but this arrangement becomes less obvious in the scapus, where the sphincter thins and eventually is represented by only scattered alveoli. The sphincter runs a considerable distance into the scapus (see Fig. 1). Circular muscles are apparent and well developed throughout the scapus, though they seem to become weaker on the scapulus. The distal portion of the scapulus has very few circular muscles. Endocoelic cinclides occur in a ring just above the limbus. The cinclides appear to be perforate and to have a normal appearance. Acontia are discharged through the cinclides and occasionally through the mouth when the anemones are disturbed. When well expanded, the column becomes a tallish cylinder flaring gently to the broad base. It may become considerably taller than the longest diameter of the base and as seen in side view the sides of the upper half may be nearly parallel. When the disc is maximally expanded, the scapulus flares outward to the edge of the disc. The scapus does not seem to be involved in this outward flare. When contraction occurs, the scapulus is completely withdrawn, and the scapus closes over the scapulus and tentacles, and little or no aperture remains. Oral Disc: The disc is always smaller than the greatest diameter of the base and is commonly about half the diameter of the base. It may be flat or somewhat concave. If concave, the mouth is sometimes taised in a central cone, though more commonly the mouth is only a slit not raised above the disc. The lips seem not to be heavily ribbed and are generally whiter and more opaque than the disc. The lips and the area around them commonly form a discrete and obvious circular spot in the middle of the disc. The two siphonoglyphs can be seen at the ends of the mouth slit. The disc may be an opaque white, translucent red, maroon, brown, or straw, or be colourless and transparent. On some specimens the mesenterial insertions may be marked as white lines, though this is uncommon. There may be reddish areas or a pair of red lines extending from the tentacle bases for a short distance onto the disc, or the whole area of tentacle insertions may be reddish. The tentacles are restricted to a narrow band around the disc and occupy no more than one-quarter to one-third of the radius of the disc. Tentacles: The tentacles are short and conical in contraction, but long, slender, and tapering to a fine point when expanded. The first two cycles are usually held vertically. The other orders are bald bent progressively more outwards and downwards towards the base. The inner tentacles are longer than the outer ones and can extend to approximately the diameter of the disc. The tentacles are usually hexamerously arranged, though occasional specimens with seven firstorder tentacles have been noted. Ninety-six seems to be the maximum, and usual, number of tentacles. The tentacles may appear colourless or may be a pale reddish or straw colour. On most anemones there is a pair of red lines on the lateral surface of the mid- and proximal parts of each tentacle, while the distal parts have no colour. When tentacles become deflated, the red lines appear to coalesce and give them a dark maroon colour. Some have each tentacle marked by a white ring at its insertion into the disc; others have red tentacle bases, with this colour extending onto the disc. Rarely, both white rings and red areas may occur on a single individual. A few specimens have been seen with maroon tentacle bases and the terminal one half to two thirds of the tentacles an opaque white. Mesenteries: There are six, or rarely seven, pairs of perfect mesenteries, and normally there is a total of four cycles of mesenteries ( = 96), although a partial fifth cycle may be present in very large specimens. The perfect mesenteries are sterile. Acontia are present. The retractors are weak and diffuse to very slightly restricted on the perfect mesenteries (Fig. 2a). The second (Fig. 2b) and third cycle of mesenteries have very small, weak retractors, and retractors

6 1975] HAND DESCRIPTIONS OF TWO SEA ANEMONES 497 FIC. 2 Camera lucida drawings of cross sections of retractors of (a) a first order and (b) a second order mesentery of Calliactis conchicola. (Column wall to the left.) appear to be absent from the fourth-order mesenteries. Parietal and pariefobasilar muscles are very weakly developed on the older mesenteries, but are more strongly developed on the youngest order. There is no free flap or fold of mesoglea to mark the parietobasilar muscle, and the branching of mesoglea near the insertion of the mesentery into the body wall is about equal on both faces of the mesentery. The number of mesenteries and tentacles is the same, and all mesenteries run from margin to base. Gonads are present on all but the perfect mesenteries, though commonly they are absent from the fourth order. No gonads were present on the partial fifth order mesenteries observed in three specimens. As Parry (1952) noted, the mesogleal sheet of the mesenteries, beyond the retractors, is rather thick and can become "crammed" with gonadial material. The sexes are separate. Cnidom: Spirocysts, basitrichs, and microbasic p-mastigophores. Size and Distribution of Nematocysts: All measurements are in microns dum). About 30 nematocysts of each type reported below were measured from seven specimens. Tentacles Spirocysts Basitrichs (rare) Basitrichs Column Basitrichs Basitrichs Microbasic p-mastigophores (rare) Actinopharynx Basitrichs (rare) Basitrichs Microbasic p-mastigophores (rare) Filaments Basitrichs Microbasic p-mastigophores Acontia Basitrichs Basitrichs X X X X X X X X X X X X X

7 498 N.Z. JOURNAL OF MARINE & FRESHWATER RESEARCH [DEC. Size: Small individuals, 5-10 mm basal diameter, have been found on the legs and carapace of a spider crab, Leptomithrax longipes. The smallest found on shells occupied by hermit crabs was 12 mm. The smallest on a living gastropod was 22 mm. The largest specimens observed occurred on living gastropods (Austrofusus glans) and were approximately 65 mm in basal diameter, although specimens almost as big occur on spider crabs.. Specimens of average size have a basal diameter of about 35 mm and, when fully extended, may be about 40 mm tall. Such a specimen has a disc diameter of about 25 mm and inner tentacles of about the same length. The outer tentacles are about half as long as the inner. Localities and Habitat: In the Otago area, specimens have been collected on shells occupied by the hermit crabs Pagurus rubricatus and Paguristes subpilosus in depths of m or more on muddy, sandy, gravelly, and shelly bottoms. At Kaikoura they are abundant in m and are observed by divers in the area. Several large collections of Austrofusus glans bearing Calliactis conchicola have been made by fishermen in the Kaikoura area. These whelks attack gillnetted fish and have been collected with fish to a depth of about 75 m. One specimen of the crab Leptomithrax longipes bearing the anemone was taken by a fisherman in 115m offshore from the Kahutara River at Kaikoura. Sampling by dredge in the Otago area extended from quite shallow water (10-15 m) to about 1400 m in the canyons off the Otago Peninsula, but no specimens of Calliactis conchicola were taken at depths greater than 120 m. Mr John Ottaway from the University of Canterbury has made his large collections of Calliactis available to me and has also provided me with the following information. In his diving in the Kaikoura area he has observed this anemone on living whelks (Austrofusus glans), Austrofusus glans shells occupied by hermit crabs, and on Leptomithrax longipes. A fisherman friend of Ottaway's also reports that this anemone is common on the same species of whelk off Lyttelton Harbour. In his diving around Kaikoura, Ottaway reports that the anemone occurs about once in each 2 m 2, that one out of every two Austrofusus has an anemone, and Calliactis occurs in a ratio of 15:4:1 on live Austrofusus, shells occupied by hermit crabs, and Leptomithrax respectively. In the Otago area, Calliactis has never been collected on living Austrofusus, which is quite rare there. However, its shells are fairly common in dredge hauls and seem to be the favoured substrate for Calliactis. These shells are commonly occupied by the hermit crabs Pagurus rubricatus and Paguristes subpilosus. Calliactis has been collected only on male specimens of Leptomithrax and the incidence of occurrence is fairly low. Of 256 male Leptomithrax examined, only 19 carried specimens of Calliactis, and these occurred only on the larger males with a carapace length of 49 mm or greater. DISCUSSION Parry's (1952) description of Calliactis conchicola differs from the one provided here in a number of points, and I am convinced that she took her description from specimens of both this species and of the new species of Paracalliactis described herein. While none of the Austrofusus glans provided to me by Mr John Ottaway carried any Paracalliactis, one of the specimens of Leptomithrax in his collection did possess one. Thus, the distribution of Paracalliactis probably includes the area from which Parry obtained her material, and it is likely that she observed both species. In the Otago area, not only do both species occur together, but both have been observed on a single shell occupied by a hermit crab, and both have been observed on a single Leptomithrax. Unfortunately, Parry did not deposit type material nor do specimens from her study seem to exist, but most of Parry's description seems to apply best to Calliactis conchicola. However, Parry described the column

8 1975] HAND DESCRIPTIONS OF TWO SEA ANEMONES 499 as "silvery white", but the colour of C. conchicola is not one that would be called silvery white. Rather it is a straw or creamy-white colour. Silvery white is a much more apt description of the whiteness of the column of Paracalliactis. Likewise, I suspect that her description of the tentacles as "short, gently tapering to a blunt tip" and of a "very pale rosy pink" colour refer to Paracalliactis and not to Calliactis conchicola. Paracalliactis has tentacles of the shape and colour described by Parry whereas long, slender, and pointed better describe the tentacles of C. conchicola, which were never rosy pink from Kaikoura or Otago. Parry commented that there are "4-5 cycles of mesenteries in all". In adult Calliactis, there are always four cycles and in three large specimens a few mesenteries of a possible fifth order existed, but were scattered and not arranged in precise patterns. They seemed more aberrations that normal mesenteries. I have dissected nearly three dozen well-relaxed specimens of both species, and in no instance was a welldeveloped fifth cycle of mesenteries present. Since Paracalliactis, like Calliactis, has only four cycles of mesenteries, the report by Parry of a full fifth cycle remains a fact that I cannot corroborate. Never, in the material examined, have there been more tentacles than mesenteries at the base, but the rest of the features of conchicola convince me that this species is properly placed in Calliactis. It was this presumption which caused me to modify the generic definition insofar as it relates to this character. Parry's description of the cnidom was obviously incomplete in that she reported on nematocysts from only the acontia and tentacles. A full cnidom is reported here. This species, C. conchicola, appears distinct, and certain of its features are unique compared with all other members of the genus. There are microbasic p-mastigophores in the column, a feature characteristic of Paracalliactis, and otherwise unknown for Calliactis. Likewise the number of tentacles agrees with the number of mesenteries at the base, which is also characteristic of Paracalliactis. The cinclides in a ring above the limbus and the well-developed ectodermal pits seem to leave no doubt, however, that this anemone is better considered a Calliactis. The separation of Calliactis from Paracalliactis is not an easy one, and a careful revision of the species of both genera, and of the generic concepts, is very much needed. Ross (1967) reviewed the behavioural and ecological relationships between sea anemones and other invertebrates and notes that it is surprising that so few anemones are found in association with living gastropods. Calliactis conchicola, therefore, takes on added interest since it occurs as a symbiont with living gastropods as well as with both hermit and true crabs. Even more interesting is the fact that this anemone occurs most frequently on living gastropods off Kaikoura, but is most abundant on dead shells occupied by hermit crabs off Otago. A partial explanation of the difference in occurrence between

9 500 N.Z. JOURNAL OF MARINE & FRESHWATER RESEARCH [DEC. the northern and southern populations may lie in the scarcity of living Austrofusus glans in the Otago area, but there is no information which explains the apparent preference, as expressed by its occurrence, of C. conchicola for living gastropods in the north. Two lots of Calliactis conchicola have been deposited as NMNZ Co. 78 and 79 in the National Museum of New Zealand at Wellington. Genus Paracalliactis Carlgren "Hormathiidae with wide basal disc forming a cuticle which may project beyond the mouth of the shell to which it is fastened. Column divisible into scapus and scapukis, the former smooth or provided in its distal part with a «*more or less complete corona of tubercles, with a thin, easily deciduous cuticle. Scapulus, at least in the preserved state, with deep longitudinal furrows. Margin distinct, more or less crenulated. Fosse deep (?), sphincter mesogleal. Tentacles thin, hexamerously arranged. Longitudinal muscles of tentacles and radial muscles of oral disc ectodermal. Two deep siphonoglyphs. Mesenteries hexamerously arranged, six pairs perfect and sterile. About same number of mesenteries, distally and proximally. Retractors rather weak to weak; parietobasilar and basilar muscles weak. TVo cinclides. Acontia thin, but long. The species of the genus live in symbiosis with hermit crabs. Their mouth may be situated dorsally as well as ventrally with relation to the mouth of the hermit. Cnidom: spirocysts, basitrichs, microbasic p-mastigophores (the mastigophores in the column too)". The above definition is identical with that of Carlgren (1949, p. 94) but has had the italicised statement "No cinclides" added to it and a query mark in parentheses has been added after "Fosse deep". Carlgren (1949) uses the absence of cinclides in his key (p. 91) as one of the characters to assist in distinguishing Paracalliactis from Calliactis, which possesses cinclides, but does not mention them in his diagnosis. This difference is obvious in living specimens, particularly when roughly handled at the time a dredge haul is dumped on to the deck of a vessel. Acontia will be seen extruded from the mouth of Paracalliactis, whereas they are extruded from the cinclides just above the base in Calliactis. It should be noted, however (see generic definition of Calliactis), that there is some question regarding cinclides in Calliactis. Carlgren (1949) questions whether they are always present. The reason for questioning the existence of a fosse in Paracalliactis is that I doubt that such a structure exists in this genus. A fosse-like depression or groove forms in the early stages of contraction of the anemone about to be described, as it does in many species, and most preserved specimens being in a contracted or semi-contracted state show this. However, this depression is absent at full expansion in the new species, whereas a fosse in the true sense exists even at full expansion. Stephenson (1928, p. 11) notes that when a scapulus is present in actinians, as it is in Paracalliactis, there is no parapet (collar), and thus there is no fosse. The conclusion one reaches from this is that a fosse should not exist in Paracalliactis. However, it seems best for the time being to simply question the existence of the fosse, and, indeed, until fresh examinations of other species of Paracalliactis can be made, this

10 1975] HAND DESCRIPTIONS OF TWO SEA ANEMONES 501 matter cannot be finally resolved. That a fosse exists seems unlikely, but, although by definition it is impossible, it is in fact conceivable that it is the definition which is at fault. Dechance & Dufaure (1959) described a new species of Paracalliactis (P. lacazei) which they reported as having both a fosse and a ring of cinclides near the base. That species has all of the generic features of a Cataphellia, and by its possession of a ring of cinclides would be unique as a Paracalliactis, Its generic identity must be considered in doubt. In general it appears we are dealing with two generically separable groups of anemones in Calliactis and Paracalliactis. Calliactis anemones have stronger mesogleal sphincters than Paracalliactis, they possess cinclides, usually have more tentacles than mesenteries at the base, and Paracalliactis anemones have microbasic-p-mastigophores in their column, whereas Calliactis usually does not. The two species we are dealing with here each raise questions about the validity of the separation of these genera. Calliactis conchicola possesses the microbasic p- mastigophores which characterise Paracalliactis. Also, C. conchicola has the same number of tentacles as mesenteries at the base. This character applies to some other species of Calliactis and all species of Paracalliactis, but in all its other characters C. conchicola is readily assignable to Calliactis. The Paracalliactis about to be described here has no fosse, as is true of Calliactis, nor does it have cinclides. But, as noted earlier, we are not certain that all species of Calliactis have cinclides. Otherwise the new species of Paracalliactis is easily assigned to this genus. If we consider the two species here and all other species assigned to Calliactis and Paracalliactis, it appears that we may be dealing with a single species complex (genus) rather than two discrete genera. An answer to this question is beyond the scope of this report and must wait for a critical re-analysis of the characters of the many species involved. Our knowledge is insufficient to resolve this matter at present. The following description is based on a single specimen from Kaikoura, about 150 specimens collected by the Portobello Marine Laboratory's r.v. Munida, and about two dozen specimens collected by commercial fishing boats working off Otago. Paracalliactis rosea n. sp. Figs 3 & 4 Paracalliactis rosea Ross, 1974, pp (Nomen nudum, I.C.Z.N. Art. 13 a (i)) Base: Generally circular in outline, but can be an elongated oval, and attached to snail shells containing hermit crabs or to crabs by a well developed cuticular material. The cuticle seems to extend over the whole base though it is thickest and most obvious around the edges. In some individuals the cuticle was noted to extend a few millimetres onto the shell beyond the limbus. The central part of the base is at best weakly attached and may not be attached at all. Pockets of loose debris were noted between the centre of the base and the shell in some instances. The base is fragile and easily damaged as one tries to remove the anemone from the shell. It is transparent and essentially colourless. Basilar muscles are weakly developed and sometimes widely separated from the mesentery.

11 502 N.Z. JOURNAL OF MARINE & FRESHWATER RESEARCH [DEC. Column: Divisible into a scapus and scapulus. The scapus bears a very thin, deciduous cuticle and may be a greyish or brownish colour due to accumulated debris. When free of debris the scapus and scapulus are both white, the scapulus whiter than the scapus, due to the presence of the cuticle on the latter. A pinkish or rosy hue is to be seen in both the scapus and scapulus and apparently is the result of seeing the brilliant pink to orange colour of the endodermal side of the throat and of the mesenteries through the white column. No colour, other than white, appears to be present in the column. The upper part of the scapus is marked by the termination of the cuticle. The scapulus is free of cuticle and becomes deeply and markedly longitudinally furrowed in contraction. The scapus sometimes becomes indented both transversely and longitudinally as it contracts and is therefore divided into rectangular blocks. Weakly to well developed but irregularly shaped tubercles are present on the distal part of the scapus and may, on large specimens, form a complete corona on contraction. The tubercles are the result of thickened areas of the mesoglea, but the epithelium of the tubercles is no different from that elsewhere on the scapus. On some individuals the tubercles are so weakly developed that they are difficult to identify, and on most individuals they are irregularly arranged and do not form a complete corona. The tubercles largely disappear as the anemone expands. In histological sections cut at 10 ^m and stained with Mallory's Triple Stain, the epithelium of the scapulus can be seen to possess numerous gland cells, and microbasic p-mastigophores are abundant. This nematocyst type is relatively scarce on the scapus. Thickenings of the scapulus are seen in contracted specimens and presumably represent scapular ridges. The sphincter appears to become smaller and weaker in the grooves between the scapular ridges and reaches only a short distance into the scapus in the grooves, whereas it appears stronger in the ridges and reaches further into the scapus. In expanded specimens the mesoglea is thickest in the scapulus and thins gradually throughout the length of the scapus. In contraction, the mesoglea of the scapus may be thicker than that of the scapulus. The mesoglea is generally thick and in the region of the sphincter may be ten times as thick as the epithelium. In the general area of the scapus the mesoglea is usually no more than five times as thick as the epithelium. The sphincter is quite variable and may be strong to relatively weak in appearance. In the scapulus it may occupy the full thickness of the mesoglea, particularly in the area of the scapular grooves, whereas it may occupy no more than half the thickness of the mesoglea in the scapular ridges. The spaces in the sphincter are small, with occasional major lamellae of mesoglea crossing from side to side (see Fig. 3). Scattered ectodermal pits occur on most individuals. These are never numerous and do not occur on the scapulus. However, they may penetrate to more than half the thickness of the mesoglea and are connected to the surface epithelium by a thin tube of tissue. In sections no special modification of the epithelium of the pits seemed evident, though the epithelium may be thicker in the pits than on the surface. The pits are visible under low powers of the dissecting microscope and are readily seen in cut surfaces of the mesoglea, in cross or longitudinally dissected specimens. Circular muscles are generally weakly developed, particularly on the scapulus, though some specimens show quite well developed mesogleal folds on the scapus. Occasional branched folds of mesoglea are present. When well expanded, the anemone assumes a low cylindrical form. The height is no more than the diameter of the disc, and the disc is about half the diameter of the base. The column flares from the margin to the base, and essentially no part of the column can be described as a cylinder with parallel sides. In contraction the anemone becomes nearly flat. It appears to expel all of the contained water and a noticeable aperture remains at the centre of the contracted anemone. Commonly a few tentacle tips may protrude through this aperture, even at full contraction.

12 1975] HAND DESCRIPTIONS OF TWO SEA ANEMONES mm Mesoglea Cuticle Mesogleal sphincter FIG. 3 Camera lucida drawing of longitudinal section of upper column of Paracalliactis rosea n. sp. illustrating the mesogleal sphincter in the groove between two ridges. (Base of anemone on left.) Arrow labelled 'Mesoglea' should lead to black area. Oral Disc: The disc has a large tentacle-free area, and the tentacles occupy about one fifth of the radius of the disc. The disc is generally held quite flat, and is transparent to translucent and only occasionally so densely pigmented as to be opaque. The primary endocoels may be white, but are generally of the same appearance as the rest of the disc. The mesenterial insertions are generally visible. The general colour of the disc is the same as the tentacles and is a pale rosy pink to a pale light orange. A few specimens with opaque white discs have been observed, but these had pink tentacles. There are no well developed lips on the mouth, which appears as a long narrow slit with two siphonoglyphs. One can see the pinkish orange throat through the mouth at times and the bright orange endodermal lining of the throat is visible through the transparent disc. As the anemone contracts, the mouth tends to open and acontia are extruded through the mouth. Tentacles: Pale pink or rosy pink to a light salmon orange or apricot. No bars, bands or other marks on the tentacles. When fully expanded the colour of the tentacles is barely noticeable and they may appear completely transparent and colourless. The usual form of the tentacles is short and tapering to a rather blunt tip. They may become longer and more slender, and the tip relatively rather pointed. The inner tentacles are longer than the outer ones., and the longest tentacles may exceed the diameter of the disc in length. The fully expanded tentacular crown usually exceeds the diameter of the base. The number of tentacles is seldom other than 96. Mesenteries: There are usually six pairs of perfect, sterile mesenteries, two pairs of which are directives. One specimen with three siphonoglyphs, three pairs of directives, and a total of eight pairs of perfect mesenteries was noted. No form of asexual reproduction has been observed in this species, and the occasional individual with other than the usual hexamerous symmetry may result from regeneration after injury or from a developmental anomaly. The distribution of mesoglea in the mesenteries is unusual. The mesoglea supporting the parietobasilar muscle on the imperfect mesenteries is several times thicker than that of the remainder, and there is a pronounced free flap of mesoglea and its associated epithelium at the place that marks the edge of the parietobasilar muscle sheet (Fig. 4b). The edge of the retractor toward the throat is sharply marked off from the face of the mesentery, as in a circumscript retractor, whereas no such sharp demarcation occurs marking the edge of the retractor toward the body wall. This characterises both perfect and imperfect mesenteries (Fig. 4a, b). The retractors are small and weak. The mesoglea supporting the best developed part of the retractor on the imperfect mesenteries is very thin in comparison with that supporting the parietobasilar sheet (Fig. 4b). The parietobasilar muscle is weakest on the perfect mesenteries and becomes progressively stronger and more obvious on the younger cycles of mesenteries. The free flap of mesoglea noted above is not present or only weakly developed on the first cycle, but is present and increasingly more obvious on the second and third Sig 6

13 504 N.Z. JOURNAL OF MARINE & FRESHWATER RESEARCH [DEC. cycle. It seems less well developed, though present, on the fourth cycle. There are never more than four cycles of mesenteries, and all mesenteries run from the margin to the base. Acontia are present on all cycles, as are filaments, though the gonads are restricted to the imperfect mesenteries. The gonads develop within the mesogleal sheet between the retractor and the filaments and become strongly lobular. The lobes of fully ripe specimens may nearly separate from the general mesenterial sheet and are attached to it by rather delicate stalks. After collection by dredging, it is quite common for fully ripe animals to extrude great masses of gonadal material which has become detached from the mesenteries. In life the mesenteries are pale creamy white, as are the gonads, filaments, and acontia. Immediately adjacent to the filaments the mesenteries are deeply pigmented with a bright orange, the same colour as the endodermal lining of the throat. This colour is quite persistent in preserved specimens. Cnidom: Spirocysts, basitrichs and microbasic p-mastigophores. Size and Distribution of Nematocysts: All measurements are in microns (,um). About 30 nematocysts of each type from each of four specimens were measured. Tentacles Spirocysts X Basitrichs (rare) 9-13X Basitrichs X Microbasic p-mastigophores (rare) X Column Basitrichs X Basitrichs X Microbasic p-mastigophores X Actinopharynx Basitrichs X Microbasic p-mastigophores X Filaments Basitrichs 9-11 X Basitrichs (rare) X Microbasic p-mastigophores X Acontia Basitrichs X Basitrichs X Size: The largest specimen observed had a basal diameter of 38 mm. This specimen had a disc of about 20 mm diameter, and the tentacular crown was spread to about the diameter of the base. At maximum extension it was about 25 mm tall. Most specimens were smaller than this and had basal diameters of mm. The smallest specimen observed came from a deep haul (approximately 1000 m) and had a basal diameter of about 5 mm. No specimen smaller than this has been observed. Localities and Habitat: This anemone has been collected only in association with hermit crabs and the spider crab Leptomithrax longipes. In shallow waters (approximately m) it commonly occurs with Pagurus rubricatus, Paguristes subpilosus and Leptomithrax. In deeper water ( m) the hermit is usually Parapagurus_ dimorphus, though according to the late Dr E. J. Batham there is some question as to the identity of this hermit crab. A single anemone occurred on a shell occupied by Pylopagurus crenatus. Shallow water specimens occur on snail shells that may also carry specimens of a Hydractinia and Calliactis conchicola. When Paracalliactis rosea occurs on a shell with Calliactis conchicola, its position on the shell is usually near the spire. C. conchicola seems to have the preferred location above the aperture of the snail shell. Paracalliactis may occur almost anywhere on Leptomithrax. The common location is on the carapace but specimens have been seen on the legs of this crab.

14 1975] HAND DESCRIPTIONS OF TWO SEA ANEMONES 505 FIG. 4 Camera lucida drawings of cross sections of retractors of (a) a first order and (b) a second order mesentery of Paracalliactis rosea n. sp. (Column wall to the left.) It may occur with Calliactis conchicola on Leplomithrax and is sometimes also accompanied by small specimens of the anemones Bunodactis chrysobathys Parry and Phellia aucklandica Carlgren. Leptomithrax bearing Paracalliactis have been collected in m of water off Taiaroa Heads, and T obtained from Mr John Ottaway a single specimen of Leptomithrax bearing Paracalliactis collected off the Kahutara River at Kaikoura in 140 m of water by a fisherman. The anemone occurs continuously from shallow water to considerable depths in the Otago area, and appears to be more abundant in deep than in shallow water. In shallow water, where it occurs in the same area as Calliactis conchicola, it is about one tenth as abundant as that species. Type Locality and Type Specimens: A holotype (NMNZ Co. 76) and four paratype specimens (NMNZ Co. 77) have been deposited in the collections of the National Museum of New Zealand at Wellington. These specimens came from a dredge haul made on 25 March 1974 in Taiaroa Canyon at a depth of m, at 171 5^ E, 45 46' S. This location is listed as Mu 74/95 in the records of the University of Otago's r.v. Munida and is the designated type locality. DISCUSSION Calliactis conchicola Parry should probably be considered in part a synonym of Paracalliactis rosea. As noted in the discussion of C. conchicola, a number of observations Parry (1952) reported for that species seem to apply better to P. rosea. It is of interest that P. rosea occurs from shallow to rather great depths, and that the distribution seems to be continuous. The specimens from deeper water are notably smaller than those from m, but no morphological differences between the small and the large specimens were discovered. Four of the five previously known species of Paracalliactis are known only from water deeper than 500 m, while the

15 506 N.Z. JOURNAL OF MARINE & FRESHWATER RESEARCH [DEC. fifth, P. lacazei, was reported by Dechance & Dufaure (1959) from m in the Mediterranean. The other four species are known from Atlantic Ocean (three species) and the Indian Ocean. The species of Paracalliactis are noted for the production by the base of a cuticle which may project beyond the aperture of the snail shell on which the anemone occurs. This cuticle, when it projects beyond the shell mouth, is referred to as a carcinoecium and seems to serve to enlarge the living room of the hermit crab. Ross (1967) suggests that this may indicate a close relationship between the anemone and the hermit crab. In the species just described, no carcinoecium seems to be produced, though the base secretes a cuticle which may extend onto the shell beyond the edge of the limbus. The species of Paracalliactis are not well known, and most of the descriptions are based on one or a few preserved specimens. However, P. rosea seems distinctive in that it does not produce a carcinoecium and in the thickened mesoglea and free flap associated with the mesenterial parietobasilar muscle. We have only incomplete descriptions of the cnidom of other species of Paracalliactis, so that detailed comparisons of P. rosea with other species are not possible at this time. The detailed description herein should make such comparisons easier for future workers. During my studies on Calliactis and Paracalliactis at Portobello, I was able to examine some of the behavioural aspects of the association between these anemones and their hosts. The results of those observations are reported separately in a following paper. ACKNOWLEDGM EN TS These studies were initiated in and completed in during sabbatical leaves from the University of California at Berkeley. I am grateful to the Regents of the University for these leaves and for the support of a John Simon Guggenheim Memorial Foundation Fellowship during I am also in debt to the late Dr E. J. Batham, the former Director of the University of Otago Portobello Marine Laboratory, for her encouragement, help, and support. Without the many kindnesses, support, and advice of Dr John Jillet and Dr Barbara Williams of the staff of the Portobello Marine Laboratory this work would not have been possible. Too, invaluable assistance was provided by Mr William Tubman, skipper of r.v. Munida, who provided much of the material this study was based upon. I also am very appreciative of the help provided by Mr John Ottaway, of the University of Canterbury's Edward Percival Marine Laboratory, who supplied me with living and preserved specimens of Calliactis and with information about this anemone and its associates. Lastly I thank the Director, Dr William Ballantine, of the University of Auckland Marine Research Laboratory at Leigh for his encouragement and the use of facilities there in the final preparation of this report.

16 1975] HAND DESCRIPTIONS OF TWO SEA ANEMONES 507 LITERATURE CITED CARLGREN, O. 1949: A survey of the Ptychodactiaria, Corallimorpharia and Actiniaria. Kunglinga Svenska Vetenskapsakademiens Handlingar (Fjdrde Serien) 1 (1): DECHANCE, M. & DUFAURE, J.-P. 1959: Une nouvelle association entre une Actinie et un Pagure. Compte rendu hebdomadaire Seance de Academie des Sciences, Paris 249: PARRY, G. 1952: The Actiniaria of New Zealand. A check-list of recorded and new species, a review of the literature and a key to the commoner forms. Part 2. Records of the Canterbury Museum 6 (2): Ross, D. M. 1967: Behavioural and ecological relationships between sea anemones and other invertebrates. Oceanography and Marine Biology : Behaviour patterns in associations and interactions with other animals. Pp (Chapter VII) in L. Muscatine & H. M. Lenhoff (eds) "Coelenterate Biology: Reviews and New Perspectives". Academic Press, New York. 512 pp. STEPHENSON, T. A. 1928: "The British Sea Anemones. Volume 1". Ray Society, London. 148 pp.