Phycologia (2006) Volume 45 (1), 1-9 075 Published 3 January 2006 , I \ I ! Creation of the subgenus Testeria Faust subgen. nov. Protoperidinium Bergh from the SW Atlantic Ocean: Protoperidinium novella sp. nov. and Protoperidinium concinna sp. nov. Dinophyceae MARIA A. FAUST'" Department of Botany, US National Herbarium. Smithsonian Institution, 4210 Silver Hill Road, Suitland, Maryland 20746, USA M.A. F'\\?ST. 2006. Creation of the subgenus Tcsteri? Faust subgcn. nov. Protoperidinium Bergh from the SW Atlantic Ocean: Protoperulinitnn novella sp. nov. and Protoperidinium concinna sp, nov. Dinophyceae. Phycologia 45: 1-9. DOl: 10.2216/04-62.1 Two new heterotrophic Protopcridinium species arc described from oceanic waters from The Gulf Stream, S\V Atlantic Ocean and Belizean Atlantic Barrier Reef Ecosystems, Caribbean Sea. Protoperidiuium novella Faust sp. nov. and P. concinna Faust Sf'. nov. show a plate formula of 4', La, 7", 4C(3+t), 6S, 5"', and 2"", which is atypical for the genus. It is charucrerizcd by a miniscule flat closure on the extreme anterior of the pointed apical horn. Apical pore complex is absent. Apical ventral plate I' disconnects from the tip of the apical horn and connects directly 10 the anterior sulcal plate (Sa) along a straight line of the longitudinal axis of the cell's sagittal plane. The shape and position of the intercalary plate (1a) is another distinctive feature fur these species, the presence of only one Ja plate. The thecal plate features of P. novella and P. concinna justifies the establishment of the new subgenus, Testeria Faust subgen. nov. The relationship with other COIl? generic species and the position within the genus Protopcridinium are discussed. Kr.v \VORIJS: Belize. coral reef-mangrove pond, dinofiagellutes. Dinophyceae , ecology. Subgenus Teste ria subgen nov., Protoperidinium novella sp. nov .. Protoperidinium concinna sr. nov .. scanning electron microscopy, taxonomy Dedicated /0 Dr Patricia A. Tester ill recognition of her significant contributions to The dynamic's of Karcnina brevis (Davis) G. Hansen & 0. Moestrup algal blooms. INTRODUCTION Protopcridiuium Bergh is a large genus of armoured dinofla? gellatcs usually without chloroplasts. Bergh (1881) realized that thecal plates always exhibit a certain basic pattern com? mon within a genus. Schutt (1895) noted the importance of morphology identifying dinoflagellates. JOrgensen (1912) em? phasized the importance of thecal plate pattern for species identification in the genus and presented new groups: e.g. Per? idinium, whose divisions were based on the shape of the first apical I' plate, and the position and shape of the dorsal epi? thecal plates, particularly the second intercalary 2a plate and the presence of three intercalary plates. Jorgensen (J 912) es? tablished a second genus Archaeoperidiniuni with only two anterior intercalary plates. Balech (1974) transferred 231 spe? cies of marine Peridinium to the genus Protoperidinium which included species with ortho, meta and para apical plate 1', intercalary plate 2a with hexa, penta and quadra-rype, four cingular plates, and six sulcal plates, and left Peridinium to include only those with ortho-type of I' plate, five or six cin? gular plates and five or six sulcal plates. Balech (1980) rec? ommended that the morphology of cingular and sulcal plates, the shape of apical plate 1', and the intercalary plates be used in species identification. ~ Corresponding author (faust.maria@nmnh.edu). The use of a scanning electron microscope provided addi? tional new information on the (inc morphology of thecal plates (Gocht & Netzel 1974; Baleen 1975, 1999; Taylor 1976; An? dreis et al. 1982; Dodge 1983, 1985; Netzel & Dilrr 1984; Lewis & Dodge 1990; Delgado & Fortuno 1991; Hansen & Larsen 19<)2: Tori umi & Dodge 19(3). Toriurni & Dodge (I <)93) found that the apical pore structures of Protoperidi? lIiUII/ species were species specific, enclosed by up to six col? lar plate sections and the narrow canal plate X, and varied in morphology. The genus Protoperidinium identified by the typ? ical thecal plate formula: Po, X, 4', 2 or 3a, 7", 4C(3+t), 6S, 5"', and 2 NN (e.g. Steidinger & Tangen J(96). Classification of Protoperidinium today are based on prominent morphological features including cell size and shape, horns or spines, apical plate J', intercalary plates, the apical pore complex (APC), ornamentation of thecal plates, displacement of cingulum and six sulcal plates (e.g. Toriumi & Dodge (1993)). The growing recognition that armoured dinoflagellates are important members of marine ecosystems has accentuated the need for detailed taxonomic studies (Yamaguchi & Horiguchi 2005). Information is Iirnited on the biodiversity of Protoper? idinium Bergh (I881) dinoflagellates from the SW Atlantic Ocean and the Belizean Atlantic barrier coral reef ecosystems. This paper illustrates the thecal plate morphology of two new Protoperidinium in recent marine collections. Both species are heterotrophic, exhibit similar cell shape, and a slender apical horn characteristic for the section Oceanica Jorgensen (1 <) I 2), the genus Protoperidinium. Protoperidinium novella sp. nov. and P. concinna sp. nov., however, differ in thecal plate mor? phology by the absence of an APC, the apical ventral plate l ' that disconnects from the tip of the apical horn, and the pres- 2 Phycologiu , Vol. 45 ( I), 2006 Table 1. Comparison of morphological features of Pro toperidin ium novella sp, nov. and P. concinnu sp . nov. and selected Prot opcridinium species.' Cell size (p.m) Taxa APC Plate " a* Length Width References P. novella no onho la 98- 116 62-7:; Present study P. concinna no onh o 1a 103-137 52- 67 Present study P. steidingerae no ortho 3a 117-/1<2 64- 1<1< Balcch Il188, p. 188. fig. 1<5: 1-7 P. oblon gum yes ortho 3NO . Shape o f apica l plate I' is ort ho. Intercal ar y plate is I a, and shape of plate Ia qu udra . APC is abse nt. C ing u lum equato rial wi th ci ngular lists, excavated, d isplaced 1X its width. S ulc us is deep . bord ered by sulcal list. Hypotheea ventra lly sli ghtl y. depressed . Two horns are present on anrapica l plates 1"" and 2 "": Thecal surface is rugose. C hro mato phores are abse nt. Fl agella arc two . TY PE: F ig . I, collec ted by Faus t. Sample no . 2.W~-200 I . ISOT YPES: Figs 2-6, sample no. 24 88 -20 02: Fig . 7, sample no . 2367? 2002 . Figs 1-1 2 11 C{:...~~ . _ ._._~~.:~._...:; "": 4' '. :. 6" 2' 2" : ... / r .... ?? 7" 1" .....10 - . T YPE SPECIES: Protop eridinium no vella sp . nov. Faust. Subgenus: Testeria Faust, subgen . nov. ETYMOLOUY : Named af te r Dr Patr ici a A . Tester in recogniti on o f her s ignificant co ntr ibutio ns to unders tand ing the dynamics of Karenina brevis (Da vis) G . Hansen & 0. Me strup harmful a lga l blooms. Din oflagell atac arma tae. Ep ithe ca uni corni s er hypoth eca bicorni s aeq ua lis. Valva apica lis (I ' ) symmetrical is "ortho ' et cornu apic ali se parate . APC absque. Disc i inte rca lis ( Ia) quadra. D isposito dis? co rum : 4 ' , 3a. 7", 4C (3 + t), 65 , 5'". et 2 "" , Pagin a rugosa thecae. ET YMO LOGY: Novella (Lat in) me an s unfamiliar structure. DISTRJ B1JTJON: Kn ow n fro m waters T he G ulf S tream oceanic cu rrent off shore fro m Po int Lookout . No rth Carolina. and ou tside Manate e Cay ( J 6?39 'N. 8~o l J ' W) . and Dou gla s C ay ( 16?43' N. l)~o I3' W), Belize. an d in The G ulf Stream off sh ore Point Looko ut. North Carolina (34 ' 13 'N . 79?56 'W ). US A. TYPE l.OCALl TY: Gulf Stream off shore r on Pierce Inlet , Florida (27 ?32 'N. 7yo54'Wl, So uthwes t Atl ant ic Ocean, US A. Sample pre? served in gilitma idehy de, curr ent ly held in the US Dinotiagellate Type Coll ec tion. US Nation al Herbarium, Department of Botany, NMN H, S m ithsonian Institution , Washing ton DC , 200 13-70 12. USA . Ce lls of P. no vella sp. no v. ar mo ured . pyriform in sha pe with a po int ed apica l horn and two ant upica l horns (Figs 1, 4, X- 12) . Epithecu and hypotheca are equa l in size. Ce lls are 98-1 J6 IJ.I1J long (L ) (X 104 .2 ::: 8 .3 ; n = 9) and 62-75 u.m wide (W) (X 70 .3 :t 5 .6 : n = 9), LfW = 1,48 (Table 2) . Th e shape of apica l pla te I' is ortho , an d ir is di sco nnected by 25 rn fro m the point ed and s lender apic al horn (Fig . I) , but apica l I ' plate in direct contac t with anterior sulcal (Sa) plate (Figs I , 2, 5 . 8) . APC is abse nt; is c harac terized by a mini scul e tJat closure o n the extreme anter io r of the pointed ap ica l ho rn (Figs 1-4, 6). Th e an ter ior int ercalary plate l a is qu au ra s ituated do rsall y adja? ce nt apical 2 ' to 4' plat es (Fig s 2-4, 9, JO). Surfac e o f P. novell a is rugose , covered by polygonal intricate ridged surfac e pattern and s ma ll un even ly dist ributed ro und por es (Figs 1-7). Ce lls ve ntra lly de? pressed (Figs I , 5 , 10 , 11). C hloroplasts are absent. Cel l co nte nt is co lourle ss or pa le p ink . T he cingulum is deep , equatorial , de scending I X itx wid th (F igs I, 5). It be ars pro min ent smooth ci ng ular list s (Figs I , 2 , 4, 5, 7 ). Fo ur cingular plates are presen t 4C (3 +t): c ingular plates IC plate is cons idered a tran sition al pla te (t), C2 and C4 plates arc ra the r narrow, whereas. C 3 plate ve ry broad and co nsti tute a major part o f the ci n? gu lum (F igs 8, 9). Row of s ma ll round pores line the cingu lum surface (Fig. 7) . nov. Faus t. Armoured dinoflagellate. Epitheca one-horned are equal in size to the two-ho rned hypo theca. Apica l plate (1' ) is sy mmetrical , ortho , and d isconnec ted from the apical horn . AP C is abse nt . With inter? ca lary p lates Ia quadra . Arrangement of plates : 4 ', l a , 7", 4C( 3 +t), 6S, 5"', and 2 "". Th ecal su rface is rugose. Order : Peridiniales Haeckel. 1894 Family : Peridiniaceue Ehrenberg, 1832 Genu s: Prot opcridinium Bergh , emend Balech , 1974 Subgenus: Tcsteria subge n. nov. Fau st , 2005 Fi~s 8-12. Line drawing of Protop eridinium no vella sp. Morphology of thecal plates illust rat ed in var ious views. Fig. 8. Ventral. Fig. 9. Dorsal. Fig. 10. Apical. Fig. II. Anrap ical, Fig. 12. Su lca l. Table 2. C omparison of the mor pho log ica l fea tures of Protoperidinium novel/a and P. concinna.' I L, length; W, width ; L'W, ra tio of length/Width; l a, intercalar y plate Ia . L W Ce ll s ize (p.m) 6.5 ::: 03 7 .3 :!: 0 .3 l a Plate L W 2 l.9 1.1 26. 5 :t 2.0 ::t 1.0 :t 0.8 w 15 .8 J3.4 Antapical horn L 28 .9 ::t 1.2 30.5 ::t 1.9 9.3 :t 0.8 7 .4 :t 0 .7 L W Ap ica l horn 19.5 :::: 2 .2 24 .9 :!: 2.2 1.48 2. 13 Rati o L/W :!: 5.6 5.0 70.3 58 .2 104.2 :!: 8.3 124 .0 :!: 11.4 P. no vella P. concinna Taxa Faust: Protoperidiniurn novella sp. nov. Faust and Protoperidinium concinna sp. nov. Faust 5 The hypothcca is oblong and ventrally depressed (Figs I, 5. 10. 1 J). Postcingular plates arc short, but 3'" plate is the largest (Figs 4. 9). The postcingular list continuously follows along the deep and nar? row sulcus (Figs I. 5. X). Sulcus bordered by widened postcingular sulcal list (Figs I. 5. 8). It is bearing six sulcal plates. where Sa plate extends anteriorly into the epithecu (Fig. 5). Two dimorphic flagella present, but not shown. Two antapical horns arc 40 ml. each with tins associated with aniapical plates I un and 2 "" (Figs I. 4. 5. 8. 9. II). Plate fonnula: 4'. la, 7". 4C(3 +t), 6S, 5'''. and 2"". HABITAT: Protoperidinium novclla sp. nov.? is a neritic. heterotro? phic dinoflagellate species. identified from The Gulf Stream oceanic current oil shore from Point Lookout. and off shore Fort Pierce Inlet. Florida (27 C32'N, 79?54'W). and SW Atlantic Ocean, USA; and the Belizean coral reef-mangrove ecosystems outside Manatee Cay and Douglas Cay. Caribbean Sea. ASSOCI/\TEIl ALC;/\I ': In the collections P. novella sp. nov. were as? sociated with coxmopoliran and world wide distributed oceanic spe? cies. The biodiversity of dinotlngcllatc species varied in each collec? tion. Photosynthetic species were: Prorocentrum CO/ll.preSSlII11 (Bailey) Abe ex Dodge, P. gracile Schutt, P. lim? (Ehrenberg) Dodge & P. micans (Ehrenberg), Pvropluuus steinii (Schiller) Wall & Dale and Pyrodinium bahamense Plate var, bahamense. Heterotrophic species were: Phalachrorna 1'<11'(1 Jorgensen and P. rotundaturn (Claparade & Lachmann) Kofoid & Mitchener. Dinophvsis caudutu Savi lle-Kent. Ornithocercus thumii (Schmidt) Kofoid & Skogsberg and O. splcn? didus Schurr. Crrarocorvs horrida Stein. and Palcophalachroma rrn? icinctuni Schiller. Subgenus: Testeria Faust Protoperidinium concinna Faust, SjJ. nov. Figs 13-25 Cellulae armatac. 103-137 fun longae ct 52-67 fun latac , pyrifor? mcs. Dispositio discorum: 4'. Ia. 7". 4C(3 +I). 6S. 5''', et 2 "", Valva apicalis I' ortho. Valva apicalis ( I ') ortho et valva intrccalaris ta quadra. APC absque. Cingulum equatoriale excavatum demotum I X ejus latitudinis. Sulcus profundus et marginatus. Hypotncca ven? traliter deprcssa. Spinae duae in valivibus antnpicales I "" et 2 "". Valvae rugosae. Chrornatophores absque. Flagellac duac. TVpJ?:: Fig. 13. collected by Faust. Sample no. 2:198-200 l. ISOTYPES: Figs 14-25. sample no. 2488-2002; Figs 7. 8, sample no. 2367-2002. TYPE LOCALITY : The Gulf Stream off shore Point Lookout, North Carolina (34?23'N, 79"56'W). SW Atlantic Ocean. USA. Sample preserved in glutaraldehyde. currently held in the National Dinofla? gellate Type Collection. US National Herbarium, Department of Botany, Smithsonian Institution, Wasbington DC. 200 13-70 12. USA. ETYMOLOC;Y: Concinnu (Latin) means harmony and proportion. DISTH Illl iTION: Known from waters outside Manatee Cay mangrove pond (16?39'N, 88? II 'W ). and Douglas Cay (l6?43'N. 88?J 3'W). Belize, and Gulf Stream off shore Fort Pierce Inlet. Florida (2r32'N, 79?54'W). SW Atlantic Ocean, USA. Protoperidinium concinna sp. nov. a heterotrophic marine species, slender in cell shape, dorso-ventrally compressed with characteristic long apical and antapical horns (Figs 13-15, 22, 23). Cell size ranges between 103-137 u.m (L) (X 124 :+: 11.4; n = 9) and 52-67 urn (W) (X 58.2 :+: 5.0; n = 9; Table 2). Epitheca and hypotheca equal in length. Thecal surface polygonally ornamented with intricate shallow ridged polygonal surface pattern and small unevenly distributed round pores (Fig. 21), and recognized as faint striations under the light mi? croscope. Cells lack the APC, characterized by a miniscule flat closure on the extreme anterior of the pointed apical horn (Figs I3-l7, 22, 23). Apical plate I' ortho (Figs 13, 16. 18, 22, 24), disconnected from pointed and slender apical horn but in direct contact with the anterior sulcal (Sa) plate (Fig. 20). Anterior intercalary plate Ia is quadra (Figs 14, \6, 23. 24) situated dorsally between apical plates 2' to 4' (Figs 16,23,24). Cingulum is deep, equatorial and displaced about I X its width (Figs 13-J5, 18, 19, 22), It bears prominent smooth cingular lists (Figs 13-16, 18-20). Four cingular 4C(3+t) plates are present: IC is a small transitional plate (t) (Fig. 20), 2C and 4C plates are rather narrow, whereas . C3 plate is very broad and constitutes a major part of the cingulum (Figs 22. 23). The hypotheca is oblong and ventrally depressed (Figs 1.1, IS, 18, I 'J). Poxtcingular plates arc short and 3'" plate is the largest (Figs 14, 23). The post cingular list follows along the deep and na rrow sulcus (Figs 13. 18, I 'J. 22). Two dimorphic Ilagella present. but not shown. Aruapical horns each with tins, associated with ant apical plates I ,,,, and 2"" (Figs 13-15. 19,22,23). Sulcal list smooth (Figs 16. 18-20) bordered by widened postcin? gular sulcal list (Figs 13, 19). Sulcus is deep and narrow composed of six sulcal plates (Fig. 26). The postcingular list continuously fol? lows along thc narrow sulcus. The anterior sulcal plate Sa extends into the epitbcca and touches the apical I' plate at the cingular-sulcai junction (Figs 18-20). Nucleus situated centrally with radiating pro? toplasmic strands. Protoplasm is clear. Thecal plate formula of P. con? cinna is: 4'. Ja. 7", 4Cn +t), 65, 5"'. and 2 '", H,\IlITAT: Populations of P. concinna cells were associated with ne ? ririe oceanic species present in coastal marine waters, coral reef-man? grovc habitats in the western Caribbean Sea: pond Manatee Cay and Douglas Cay. Pelican Cays Archipelago, Belize (Faust 2000), The Gulf Stream off shore Point Lookout. North Carolina, and off shore from the Fort Pierce Inlet. Florida. SW Atlantic Ocean (Faust & Tester 20(5). Balcch (I 'J88) recognized a morphologkally similar species, P. stcidingcrac Balech, in samples collected in both warm waters of southern Braz.il (3:1.2-35.4?C) and in cold waters of the Southeastern Atlantic Ocean (24.7-27.YC). i\SSOCI /\r1 ,rJ ,\I.c;I\I-:: In the collections P. <:onC;1II1<1 from Manatee Cay were associated with Diplopsalis lenticula Bergh. Diplopsalopsis sp., Dinophysis rot undata Claparedc & Lachman, Diplopelta sp., Lin? golodinium polvcdrum (Stein) Dodge, and Prorocentrum elegans Faust. Harmful species included: P. lima (Ehrenberg) Dodge, and P. hoffmannianum Faus t. DISCUSSION According to the subdivision of the genus proposed by Balech (1974, 1975, 1979. 1988. 19(9) and Abe (1936, 1(81), Pro? toperidinium novella and P. concinna can be attributed to sec? tion Oceanica in the genus Protoperidinium. Some unique morphological features, however, characterize P. novella and P. concinna different from species in the section Oceanica. Morphology of two new species Comparison of morphological features of P. novella and P. concinna and selected Protoperidinlum. species in the section Oceanica are listed in Table 1. Protoperidinium novella and P. concinna differ in morphology from other congeneric spe? cies based on three morphological characters: (1) the extreme anterior of the apical horn is pointed characterized by a mi? nuscule flat closure, absence of APC (Figs 1-3, 16, 17; Table 1); (2) the apical ventral plate l ' disconnects from the tip of the apical horn; and (3) presence of two intercalary plate la. The plate formula of P. novella and P. con cinna is as follows: 4', l a, 7", 4C, 6S, 5"', and 2 'm. The unique plate structures on the episome of P. novella and P. concinna arc supported by SEM pictures (Figs 1-7, 13-21). The morphological features that characterize them are stable characters and not aberrant forms of certain 'normal Protoperidinium': Comparing the presence or absence of APC from line draw? ings is troublesome. Balech (l979, 1988) and Steidinger & Tangen (l996) reported no APC on P. steidingcrae. All spe- 6 Phycologia. Vo l. 45 ( 1).2006 Figs 13-17. Scanning elect ro n micrographs o f Protoperidini um co nc inna sp. nov ., Faus t. Fig. 13. Ventral view, Ce ll is sle nder wi th a lon g pointed ap ica l ho rn and two antupical horns . Ap ica l plate) ' ortho disconnected fro m the apica l horn (arro wheads) , C ing ulum is disp laced width by I X. A PC is absen t. Left sulcal Jist is wide . Fig. 14. Dorsa l view . Api cal horn po inted . Ant erio r intercalary ( Ia) p late is large. C ing ulum is equatoria l with s moo th c ing ula r list s . Postc in ? gu lar plate (3"') is ve ry large . Antapica l horns eq ual in length. bro ad pro xi mall y, poi nted di stall y. F ig. IS . Epi the ca ex ca vated ventra lly. Location of apica l plate 4 ' is long and narrow, si tuated adjacent interca lary pla te l u and api ca l pla te I ". Fig. 16. Apical view o f cpi theca . Apical horn pointed, and AP C abse nt (arro whea d). Intercalary plate Ja is large . Intercalary band sli gh tly striated. Fig. 17. Ti p of api ca l horn is a mini scule fiat c los ure, void of an apica l pore (a rrowhead). T hecal s urface rugose with scattered pores . cies in the section Oceanica show typi ca l thecal morphology. But some publi shed figu res are to some ex ten t uncertain as to the exact fea ture of the APC or intercalary plates in apical views . Ill ustrati ons of the APC in SEM pictu res are limited to a few specks making co mparison wit h othe r spec ies difficult: P. ob lon gum (Hansen & La rse n 199 2; Tourimi & Dod ge 1993), P. oceanicum (Tori umi & Dodge (993). and P. de ? p ressum (Abe 1981 ; Dod ge 1985 ; Tori urn i & Do dge 1993). Dis tinctive recognizable feat ure of P. no vella and P. CO II ? cinna concerns the arc hitec ture of apica l pla te I ' which di s ? co nnects from the tip of the apica l ho rn situa ted direc tly along a stra ight line of the lon g itu d ina l axis at the ce ll's sag itta l plane. Plate I ' mai nta ins its typica l e longa ted or tho- shape and seems tota lly d isconnect ed fro m the api ca l horn on wh ole thecae. Such a feature of plate I' has only been discovered on P. steidin ge rae (B alech 1979). T he pla te I' not on ly d isconnec ts from the pointed apica l horn but is in direct contact with anteri or sulcal pla te Sa and a ve ry nar row IC plate located in (he c ing ulum-s ulcus j unc ture ; 2C and 4C plates are also rath e r narro w, whe reas 3C is very broad and constitutes the maj or part of the c ing ulum. A ltho ugh P. stei ? d ingerae shares a fe w import an t characteristics wi th these two new spec ies , it ca n be di stin guished from my s pec ies by po ssessing three api cal inte rca la ry p lates . T he ap ica l plate I. ' of the sec tion Oceanica and o ther s pec ies in Pro top eridin ium (Tabl e J), ex tend fro m the tip of the ap ica l horn and ends at Fau st : Protoperi d ini um novella sp, nov. Fau st and Prot operi dinium concinna sp . nov. Faus t 7 Figs 18-21. Scanning electron micrographs of Protoperidin ium co ncinna sp. nov.. Faust. Fig. 18. Ventral apical view of epltheca. Apical plate I ' is ortho and disconnected from the apical h OI11. Cell ventrally depressed. Fig. 19. Cingulum is descending IX its width. Cingular list is smooth. Sulcus deep, narrow, and bordered by smooth sulcal lists. Fig. 20. Apical plate \ ' touches the sulcal Sa platelet extended into the c piihcca and touches transition plate (t) at the cingular-sulcal junction. Fig. 21. Thecal plate surface rugose with small unevenly distributed round pores (arrows). the su lcus on the ve ntra l surface of the e pisome (Abe 198\ : Toriurni & Dod ge 1( 93). Protoperidin ium novella and P. co ncinn a pos sess o nly one dorsal intercalary plate (Tables I , 2). Th is small dorsal 1a plate is only recogn izabl e on tilt ed SEM stub (Figs 2, 16 ; A be 1981 ). The morpho logy of plates o n the episome on the se new species is disti nc t but co mparable in line drawings of species in the sec tion Oceanica (S te id inge r & Williams 1970; Balech 197 9, 1988 ; Abe 1981 ). SEM pictures of spec ies in the section Oceanica are few and often very small to recognize thecal det ails (Delgado & Fortune 1( 91) and at times inconsistent with so me features of species. In fact, P. ob longum is illus? tra ted wi th o nly on e la inte rcalary plate plu s an APC (Ha nsen & Larsen 1992), in other publ icati ons the sa me species ex? hib iti ng 3a plates p lus an AP C (Do dge 1985 ; Tori umi & Dodge 1993). In co ncl usion, I demon st rat ed unequi vocall y that P. novella and P. concinna lack co ntact betw een api cal plate I ' and the tip of apical hom, APC absent, a nd only la intercalary plate present. I co nc lude tha t P. novella and P. concinna are dif? fe ren t fro m all other Protop eridin ium. Separation of new species Protop eri din iuni novella and P. concinna are separab le from each other based on cel l shape and size, len gth of apica l and untap ical horns and dimension of l a interca lary plate (Table 2). Both spec ies ex hib it pol ygonal int ricate ridged surface pat ? tern (Figs 5. 19 ) . The di fferences arc ( I) cell sha pe of P. novel/a is broader with a rati o L/W 1.48 [cell length (L) and ce ll width (W )j, incl ud ing a shorter and wider ap ical and hy? po rheca l horns and a sma ller la intercal ar y plate ; (2) shape of P. concinna is s le nde r, cell s ize lon ger wi th a rat io of L/W of 2.13. including narrower ap ical and antapical ho rns and lager Ia interca lary plate ; (3) sulca l Sa plate of P. co ncinna ex te nds into the epitheca and tou ches apica l I ' pla te and ' tran? s itiona l' t-plate in the cingulum-sulcus j unctu re (Figs 13, 20); (4) en gen ders ch ange in the plate rel ati onship of the ventral area caus ing a distinct depression ventra lly (Figs 13, 15, 18, 19) ; and (5) the se featu res are di fferent from each other in structura l re lation s wi thi n the ve ntra l area and also in the re ? lati on s between the ve ntra l area and the fo rwa rd be ndi ng api? ca l horn o n P. concinna (F ig . 15) whe n compa red to upward apical horn on P. no vella (Fig . 6). Placement of new species in genus Protoperidinium T he morphology and plate tabulati on of P. no vellu a nd P. concinna sugges t tha t these species might be closely rel ated to m embers o f the sec tion Oceanica. Th e situati on is, how? ever, problematic for P. no vella and P. co ncinna because these two species are characterized by thre e d istinct fea tures , wh ich 8 Phycologia, Vol. 45 (J), 2006 4"' Figs 22-26. Line drawings of Protoperidinium concinna sp. nov. Faust. Morphology of plates illustrated in severa l views. Fig. 22. Ventral. Fig. 23. Dorsal. Fig. 24. Apical. Fig. 25. Hyporhccal. Fig. 26. Sulcal. are quite uncommon in the genus Protope ridinium. Whether or not to place these two species in the genus Protoperidinium is a worthwhile discussion (Figs 1-3, 16, 17). The variations of epithecal plate arrangement, deviation from the typical plate formula, have been well known in the genus Protoper? idinium. These variant forms are classified in the distinct sub? genus such as Archacperidinium based on the position and shape of the first I' apical plate and those species with only two 2a anterior intercalary plates, e.g. P. consimilis and P. valgus (Table 1; Abe 1981). Sournia (1986) considered Ar? chaeperidinium to be taxonomic junior synonym of Protoper? idinium. Fensome et al. (1993) prefer to retain Archaeperi? dinium at generic rank to enable practical subdivision of the large gcnus Protoperidinium. In the freshwater genus Peridinium, the presence or absence of APC has been regarded as difference at subgeneric level rather than the generic separation (Baleeh 1988). Balech (1995) separated species in the genus Alexandrium into two subgenera, Alexandrium and Gessnerium by recognizing syn? onymy in APC architecture and ventral plate I' morphology of species. Furthermore, among Protoperidinium. species, ab? sence of an APC is few, and recognized only in other related dinoflagellate genera, e.g. Gotoius mutsuensis (Abe 1981) and G. abei (Matsuoka 1988) in the diplopsalid group. The situ? ation in P. novel/a and P. concinna is comparable to this prac? tice. In conclusion, r believe that P. novella and P. coucinna are distinct enough from all other species of the genus Protoper? idinium and it is appropriate to classify them as a new sub? genus, I, therefore, propose to establish the subgenus Tcstcria Faust, subgen. nov. in the genus Protoperidinium. r have se ? leered P. novella sp. nov. Faust as the type species, and P. concinna sp. nov. Faust a second species. ACKNOWLEDGEMENTS I thank Dr Klaus Rutzler for the use of the Smithsonian's field laboratory facilities at Carrie Bow Cay, Belize, and Sabrina Varnam for collecting water samples from The Gulf Stream, National Ocean Service, NOAA, Beaufort, NC. 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