The species of Hawaiian sea anemone described by Verrill (1928)
as Tealiopsis nigrescens is redescribed and referred to the genus Anthopleura

Dunn, Daphne Fautin

Pacific Science

ScholarSpace at University of Hawai'i at Manoa

Pacific Science (1974), Vol. 28, No.4, p. 377-382Printed in Great BritainRedescription of Anthopleura nigrescens (Coelenterata,Actiniaria) from Hawaii IDAPHNE FAUTIN DUNN2ABSTRACT: The species of Hawaiian sea anemone described by Verrill (1928)as Tealiopsis nigrescens is redescribed and referred to the genus Anthopleura.IN TWO PREVIOUS PAPERS (Dunn 1974a, b), Idiscussed the lack of recent taxonomic workon the sea anemones of Hawaii. This paper,dealing with an actinian first described fromHawaii by A. E. Verrill (1928) as Tealiopsisnigrescens, updates the taxonomy and describesthe species in detail.Observations were made on over 50 liveanimals, four dissected specimens, and histo-logical sections of 10 others. Nematocystmeasurements were made from 10 animals.Anthopleura nigrescens (Verrill 1928: 26)Tealiopsis nigrescens Verrill, 1928: 26.Bunodactis nigrescens Carlgren, 1949: 65.HabitatThis actinian occurs from the high intertidaldown to the shallow subtidal zone on the under-sides or in holes of pieces of rock and deadcoral scattered along sandy shores; and also onrock benches, usually in cracks or tidepools.SizeThe diameter of the oral disc of an expandedanemone is generally 10-15 mm, approximatelyequal to that of the pedal disc. The centralportion of the column is slightly narrower thaneither end. The height is about 10-15 mm also.Occasional individuals reach 20-25 mm indiameter and height.I This investigation was supported by National Insti-tutes of Health Fellowship 1 F02 GM54232-01 from theInstitute of General Medical Sciences. Manuscript re-ceived 15 August 1973.2 University of Hawaii School of Medicine, Depart-ment of Pharmacology, Leahi Hospital, 3675 KilaueaAvenue, Honolulu, Hawaii 96816. Present address:School of Biological Sciences, University of Malaya,Kuala Lumpur, Malaysia.BaseThe strongly adherent base is usually circularin outline. The pedal disc is lighter in colorthan the column, normally being light brown.Mesenterial insertions are visible through it asdark radial lines.ColumnThe color of the column, usually dark gray-brown or black, gave the animal its specificdesignation, but in individuals from somelocalities (e.g., Black Point, Oahu) it may havea reddish cast.In life, the strongly adhesive verrucae (allabout 0.5 mm in diameter) usually hold bits ofgravel and broken shell (Fig. 1) so that theanemone may be completely encased in gravel.The verrucae, arranged in longitudinal endo-coelic rows with 8-10 suckers per row, do notdiminish in size basally, and extend down to thelimbus. They may be paler than the rest of thecolumn (Fig. 1).White-tipped acrorhagi, which may have apinkish cast in the specimens with a reddishcolumn, form a single ring at the top of theparapet (Fig. 1), proximal to which is a shallowfossa. The acrorhagi are lobed (Fig. 2) and endo-coelic in position. Therefore the number ofacrorhagi is equal to that of the rows ofverrucae.Oral DiscThe oral disc is normally flat, althoughoccasionally the anemone extends its oral areainto a cone, at which times lips may be formedtemporarily. The area immediately surroundingthe mouth is black. The ground color of theoral disc is lighter than the column, and themesenteric insertions are marked as dark lines.The endocoelic area between two such lines is377378 PACIFIC SCIENCE, Volume 28, October 1974FIG. 1. Expanded Anthopleura nigrescens. Note especially the bits of gravel held by the light colored verrucae, theacrorhagi, and the position in which the knobbed tentacles are held: (Photograph by S. Arthur Reed.)FIG 2. Cross section of an acrorhagus. Scale is 200 frm.- ?ll.IiLJ!l:llLU1!fiSl!1J!Redescription of Anthopleura nigrescms-DuNN 379FIG. 3. Cross section of Anthoplcttra nigrcscens. Note the free flap of the stronger retractor muscles. Scale is 500 pm.lighter in color and may even be white, althoughthose areas over the primary endocoe1s aresometimes orange. More than half the diameterof the oral disc is free of tentacles. The ecto-dermal radial musculature of the disc is strong.TentaclesThe tentacles, which have perforate tips,occur only at the periphery of the oral disc, oneover each exocoel and endocoel. Therefore,their number is twice as great as that of theacrorhagi, and ranged from 36 to about 80 inthe several specimens in which they werecounted. The inner tentacles are brownish grayto orange, usually the same as the color betweenthe mesenterial insertions. They are typically10-12 mm in length and are held more or lessvertically (Fig. 1). The shorter outer tentacles,which are lighter in pigmentation, often almosttransparent, hang downward over the margin.All the tentacles are very slim, blunt-tipped oreven slightly knobbed (Fig. 1), and may beconstricted at several points along their length.They change form quite readily, and those ofpreserved specimens are generally much shorterand stouter. Each inner tentacle, and occa-sionally the outer ones also, has a row of whitesplotches on its oral face (Fig. 1).The tentacular circular musculature is endo-dermal and the longitudinal muscles are ecto-dermal. The ectoderm comprises about 70 per-cent of the cross-sectional width of the tentaclewall, and the endoderm 20 percent.Mesmteries and Internal AnatolJryThe retractor muscles are strong and aregenerally diffuse, although those of the inter-mediate cycles of mesenteries may be almostreniform. The peripheral edge of the strongestretractors forms a free flap one-third to one-half the length of the attached portion of themuscle (Fig. 3). The mesogleal lamellae of thestronger retractors are more highly branchedthan are those of younger mesenteries. Theparietobasilar muscles are also strong, with afree flap at their inner edge.The mesenteries have large oral stomata andsmaller marginal stomata. The number of380 PACIFIC SCIENCE, Volume 28, October 1974FIG. 4. Cross section of the sphincter of Anthopleura nigrescens. Scale is 90/hill.mesenteries is the same at both ends of thecolumn, and all but the smallest have tripartitemesenterial filaments. Most or all of the strongermesenteries are fertile in gamete-bearing indi-viduals, but only ova were seen. It is likely,therefore, that this species is dioecious. Themajority of the mesenteries are complete.The white, ribbed actinopharynx is half thelength of the column. The ectoderm and endo-derm of the actinopharynx are about equal inwidth and the mesogleal layer is less than one-third the width of each except in the ribs, wherethe mesoglea accounts for most of the increasedwidth. In the ribs the ectoderm is often some-what wider and the endoderm equal or slightlynarrower than in other parts of the throat. Upto four siphonoglyphs were seen in animalsthat had been sectioned transversely, but noneof the mesenteries attached to siphonoglyphswere directives. In fact, no directive mesenterieswere found. The mesenteries attached to thesiphonoglyphs were fertile in some individuals.The relatively weak circumscribed ovalsphincter is located at the base of the shallowfossa proximal to the acrorhagi. Its mesoglealprocesses are more or less pinnately arrangedand not highly branched (Fig. 4). They arelonger and more numerous on the basal thanthe oral side.The circular musculature of the column isendodermal. The ectoderm and endoderm of thecolumn are equally thick, each being three tosix times the width of the mesoglea.This species lacks zooxanthellae.CnidomSpirocysts, basitrichs, atrichs, microbasicp-mastigophores.Distribution and Size of NematorystsTENTACLES: Spirocysts, 10.3-28.2 x 1.9-3.8p,m (67); basitrichs, 16.0-21.6 x 1.7-2.8 p,m (84).ACRORHAGI: Spirocysts, 14.1-28.2 x 1.9-3.6p,m (66); atrichs, 27.3-43.2 x 2.8-4.7 p,m (61).COLUMN: Basitrichs, 11.3-16.0 x 1.7-2.4 p,m(59); basitrichs, 16.5-22.6 x 2.4-3.8 p,m (74).Redescription of Anthopleura nzgrescens-DuNNACTINOPHARYNX: Basitrichs, 20.7-27.3 x 1.9-2.8 /lm (53).FILAMENTS: Basitrichs, 13.2-18.7 x 1.7-2.6/lm (62); basitrichs, 20.7-29.1x2.4--3.8/lm(36); microbasic p-mastigophores, 15.0-18.8 x2.8-4.7 /lm (37).DistributionI have found this species on rocks along thesandy beach of Moku-o-Loe (Coconut Island)in Kaneohe Bay, Oahu, on the rocky benchesbetween Black Point and Diamond Head, andon rocks along Kewalo Basin. I have failed tofind it on the rock benches of Hanauma Bay,and in several sand-and-rock habitats alongthe east and north shores of Oahu. I have notlooked for it on islands other than Oahu.Verrill's type material came from Kauai.This species has been observed in aquaria todivide longitudinally, and this may account forthe lack of directive mesenteries in the speci-mens examined histologically.DISCUSSIONVerrill's (1928) description of Tealiopsisnigrescens is brief and quite accurate in the fewdetails it provides. However, his statement that"The rows [of verrucae] are the same as thenumber of tentacles ... " is clearly incorrect,since there are exactly twice as many of thelatter as the former. It has been my experiencethat all the verrucae are about the same size,although Verrill says differently. I did not havethe opportunity to examine Verrill's typematerial, but there is no doubt that his descrip-tion refers to the species redescribed in thispaper.In Carlgren's (1949) monograph of the seaanemones of the world, the genus Tealiopsis isnot recognized, and species that had beenassigned to it are placed partly in the genusStomphia, partly in Bunodactis. The endodermalsphincter of the Hawaiian species clearly rulesout its inclusion in Stomphia, a member of thesubtribe Mesomyaria. Carlgren (1949) placedTealiopsis nigrescens in Bunodactis, perhaps be-381cause Verrill (1928) had not mentioned that theanemone has acrorhagi. Species of Bunodactismay have marginal pseudospherules, but notmarginal spherules. The possession of thelatter (acrorhagi) by Tealiopsis nigrescens def-initely places it in the genus Anthopleura. Thisfact has been recognized by marine zoologistsin Hawaii for some time, and the name Antho-pleura nigrescens has been used in publication(Matthew 1967, Rosin 1969).Carlgren (1949) recognizes 29 species ofAnthopleura, 19 of them from the Pacific Oceanand/or the Indian Ocean. In addition, Stephen-son (1935) mentioned that anemones he saw onthe Great Barrier Reef and the "Cape Penin-sula" are similar or identical to A. thallia, whichis listed by Carlgren (1949) as a North Atlanticand Mediterranean species. At least seven ofthese 20 species possess zooxanthellae.AlthoughStephenson (1928) stated that color is oftenunreliable as a systematic character in seaanemones, it is very consistent in A. nigrescensand, therefore, can be considered in compari-sons with other species. None of the 20 con-forms to the description of A. nigrescens.Since the publication of Carlgren's (1949)monograph, five new species of Anthopleurahave been described: A. elatensis (England1969), A. panikkarii (Parulekar 1968), A. midori,A. kurogani, and A. asiatica (Uchida andMuramatsu 1958); two species formerly as-signed to other genera have been redescribedas belonging to Anthopleura: A. elegantissimaand A. artemisia (Hand 1955); and the develop-ment of an unnamed species of Anthopleura wasstudied (Atoda 1954). All of these additions areIndo-Pacific and all differ from the Hawaiianspecies in some respects. Therefore, the smallblack sea anemone from Hawaii, described byVerrill (1928) as Tealiopsis nigrescens, remains avalid species and is reassigned to the genusAnthopleura.ACKNOWLEDGMENTSI wish to thank Dr. S. Arthur Reed for takingphotographs of Anthopleura nigrescens, andDr. Cadet Hand for his critical reading of themanuscript. I acknowledge the use of facilitiesin the Departments of Pharmacology, Pathol-382ogy, and Tropical Medicine/Medical Micro-biology of the University of Hawaii School ofMedicine, Leahi Hospital.LITERATURE CITEDATODA, K. 1954. Postlarval development of thesea anemone, Anthop/eura sp. Sci. Rep.T6hoku Univ., 4th ser. (BioI.) 20: 274-286.CARLGREN, O. 1949. A survey of the Ptycho-dactiaria, Corallimorpharia and Actiniaria. K.svenska VetenskAkad. Hand!., Fjarde ser.1(1): 1-121.DUNN, D. F. 1974a. Actiniogeton sesere (Coelen-terata, Actiniaria) in Hawaii. Pacif. Sci. 28:181-188.---. 1974b. Radianthus papi//osa (Coelen-terata, Actiniaria) redescribed from Hawaii.Pacif. Sci. 28: 171-179.ENGLAND, K. W. 1969. Anthop/eura elatensisn. sp. (Actiniidae: Actiniaria) from the RedSea. Israel J. Zoo!' 18: 1-7. .HAND, C. 1955. The sea anemones of centralCalifornia. Part 2. The endomyarian andPACIFIC SCIENCE, Volume 28, October 1974mesomyarian anemones. Wasmann J. Bio!.13: 37-99.MATHEW, K.1967. Observations on Anthop/euranigrescens (Verrill). Bul!. Dep. mar. bio!.Oceanogr., Trivandrum Univ., India 3:41-44.PARULEKAR, A. 1968. On a new species of seaanemone from Maharashtra, India. J. Bom-bay nat. Hist. Soc. 65: 590-595.ROSIN, R. 1969. Escape response of the sea-anemone Anthop/eura nigrescens (Verrill) to itspredatory eolid nudibranch Herviel/a Babaspec. nov. Veliger 12: 74-77.STEPHENSON, T. A. 1928. The British seaanemones. Vo!. 1. Ray Society, London.xii + 148 pp., 14 pIs.---. 1935. The British sea anemones. Vo!. 2.Ray Society, London. ix+426 pp., 33 pIs.UCHIDA, T., and S. MURAMATSU. 1958. Noteson some Japanese sea-anemones. J. Fac. Sci.Hokkaido Univ., ser. 6 (Zoology) 14: 111-119.VERRILL, A. E. 1928. Hawaiian shallow waterAnthozoa. Bul!. Bish. Mus. 49. 30 pp.....=_=::::z=u__~.::::J.....==:mzz;;:;;.....-=.

Redescription of Anthopleura nigrescens (Coelenterata, Actiniaria) from Hawaii

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Redescription of Anthopleura nigrescens (Coelenterata, Actiniaria) from Hawaii

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