The naupliar stages of Oithona oligohalina are described and compared with those of O. ovalis

Fonseca, Vera Lúcia

Prado, Maria Scintila de Almeida

Brazilian Journal of Oceanography

English

Cadernos Espinosanos (E-Journal)

Bolm Inst. oceanogr., S Paulo, 28(2) :17-22, 1979 THE NAUPLIAR DEVELOPMENT OF OITHONA OLIGOHALINA, FONSECA & BJORNBERG, 1976 VERA LUCIA FONSECA & MARIA SCINTILA DE ALMEIDA PRADO Instituto Oceanográfico da Universidade de são Paulo Synops i s The naupliar stages of O~hona o~gohalina are described and compared with those ofO. ov~. Introduction The females were collected at Station I. O~ona o~gohalina has been recently Nauplii I and 11 of O. ov~ were described from a Brazilian tropical also obtained in the laboratory to make estuary, in the Cananéia region, South sure of the identification of both littoral of the State of são Paulo, species. They were reared at Ubatuba, Brazil (Fonseca & Bjornberg, 1976). North littoral of são Paulo State, Brazil. Santos (1970) identified a second The same method was used to rear the species of O~ona from Cananéia waters two species: as O. heb~. Later on Fonseca & Ovigerous females were isolated and Bjornberg (1976) described this species placed in Petri dishes containing filtered as O. o~gohalina. Bjornberg (1968, sea-water collected in the same environ-1972) recorded two forms of O. ov~ ment as the animaIs. The animaIs were nauplius VI. Fonseca (1976) studied the fed with a culture of chfamydomona6. The annual variation of the O~hona species water was renewed every 8 hours to avoid in Cananéia waters and verified that the the excess of bacterial proliferation. two forms recorded by Bjornberg (op. cit.) The animaIs were kept at 20°C ± 1 and corresponded to the nauplius VI of O. were observed under a estereoscopic M5-ov~ and O. o~goh~na. Wild microscope. Soon after spawning the Thp present paper describes for the females were taken out the culture first time naupliardevelopment of O. dishes. Some of the nauplius I were o~goh~na and these are compared to the also picked out and preserved. The rest developmental stages of O. ov~. of the nauplii were left to continue Material and methods The material studied was obtained from fixed samples and from animaIs reared in the laboratory. The study was undertaken in the Cana-néia region. Plankton samples were taken monthly (June, 1973-May, 1974) at the three follcwing fixed stations: the first (St. I) located in the inner part of Taquari River, the second (St. 11) at the entrance of it and the third (St. 111) in Trapande Bay. The influence of coastal water decreases from St. 111 to St. I. Surface plankton samples were taken by means of a zooplankton net type WP3 re-duced to half the size and mesh aperture 75 )..Im, because of the small depth of the river. The first and second naupliar stages of O. o~goh~na were obtained from ovigerous females in the laboratory. Publ. nQ 445 do In6~. o~eano9h. da U~p. their development to nauplius 11 and then were also preserved for posterior observations. The morphological observations of the specimens were made under a binocular M20-wild microscope. A micrometric eye-piece was used for measurements and a camera lucida for drawings. Descriptions of the developmental stages of Odhona oügohaV..na Syrribols used to describe the segmen-tation and setation of the appendages: Numbers alone=number of setae; spine=s; (+) indicates separate groups of setae; (:) separates setae belonging to differ-ent segments; (O) indicates the absence of setae on the segment; term=terminal; S-segment (Nomenclature used according Bjornberg, 1972). Nauplius I (Fig. la) Length = 0.11 mm (1 specimen) . 18 Bolm Inst. oceanog r., S Paulo, 28(2), 1979 Oval shape, almost round. Caudal arma-ture: 2 fine setae. Antennule, 0:0:1:2. Antenna with coxopod, 1; basipod, 1; endopod, 1+2; exopod, 6. Mandible with coxopod, basipod, endopod (2s: 2+2), exopod (O :4) . Fig. la. Nauplius I, Oithona o~gohalina, 0.11 mm. Nauplius II (Fig. lb) Length = 0.13 mm (1 tpecimen) . Oval shape, almost round. Labrum, not observed. Caudal armature = 2 thin pos-terior setae, 2 thin ventral setae (= maxillules). Antennule, 0:1:2:3 + tuft of setules. Antenna with coxopod, 1 large spine + 1 setae; basipod, 2; endopod, 2 + 2; exopod, pre-terminally segmented, 0:3 + 3. Mandible with coxopod, basipod, 1; endopod, 3:3 + 1; exopod, 4S, 4. Fi g. 1 b. Naup 1 i us I I, O. oligohalina, 0.13 mm. Nauplius III (Fig. lc) Length = 0.14 mm (1 specimen) and 0.13 mm (2 specimens). Oval shape. Labrum, rounded anteriorly and crenate posteriorly, with setose margin. Caudal armature = 2 pairs of latero-terminal thin setae, 2 spines, shorter than the setae, and placed Fig. lQ. Nauplius I I I, O. oligohalina, 0.14 mm. between them. Antennule (Fig. 2a), 0:1: 2:3 + 4 termo Antenna (Fig. 2b) with coxopod, 2s; basipod, 2; endopod, 2 + 2 term; exopod, 1:3 + 3. Mandible (Fig. 2Q) with coxopod, basipod, 2; endopod, 3:4; exopod, 4S, 0:1:1:2. Maxillule, 2s, one on each side of the body, placed ventrally and pre-caudally. a Fig. 2a. Nauplius I I I , antennule from Figure 1 Q. Fi g. 2b. Naupl ius 111, antenna from Figure 1 Q. Fig. 2c.. Nauplius I I I , mandible from Figure 1 c. . Nauplius IV (Fig. ld) Length = 0.16 mm (8 specimens) and 0.15 unn (2 specimens) . Oval shape, beginning segmentation in the posterior part of the body (Fig. ld). Labrum = anterior margin with a small medium protuberance, posteriorly crenate, with lateral tufts of setules and two bigger setae between them. Caudal armature like stage 111, although the 2 spines placed between the lateral terminal setae are longer, reaching in this stage the .~ FONSECA & PRADO: O. oligohalina: naup1iar deve10pment 19 / Fig. 1d. Naup1ius IV, O. oligohalina, 0.16 mm. same length as the setae. Antennule, (Fig.2d) 0:1:1 + 1:5 or 6 se tuIes + 4 termo Antenna (Fig. 2e) with coxopod, 2s; basipod, 2; endopod, 2 + 3 term; exopod, 5S, 1:1:1:1:2. Mandib1e (Fig. 26), like in stage 111, but the setae are more de-veloped. MaxiIlu1e (Fig. 2g) with lobe I (2s lateral + 2 setae), lobe 11 (2s, short, distaI + 1 Iong seta) • Fi g. 2d. Naup1 ius IV, antennu1e from Figure 1 d. Fig. 2e. Nauplius IV, antenna from Figure 1 d. Fig. 26· Nauplius IV, mandible from Figure 1 d. Fig. 2g. Naupl ius IV, maxillu1e from Figure 1d. NaupZius V (Fig. le) Length = 0 .17 nm (6 specimens) and 0.18 mm (4 specimens). Body elongated with the caudal region tapering (Fig. le). Labrum like nauplius IV. Caudal armature=terminal setae, Fig. 1e. Naup1 ius V, O. oligohali~a, 0.17 mm. lateral setae and the two terminal spines between them are more deveIoped than in s tage IV. Antennule (Fig. 2h) , O: 1: 1: 1 (long and thick): 6 + 4 termo Antenna (Fig. 2i) with coxopod, 2s; basipod, 2; endopod, 2 + 3 term; exopod, 6S, 1:1:1: 1:1:2. Mandible (Fig. 2j) like stage IV. Maxillule (Fig. 2R) with basipod; lobe I, 3 + 1 long term; Iobe 11, 2 + 1 Iong termo Fi g. 2h. Naup1 ius V, antennu1e from Figure 1 e. Fig. Zi. Naupl ius V, antenna from Figure 1 e. Fig. 2j. Naupl ius V, mandible from Figure 1 e. Fig. 2R. Naupl ius V, maxi 11 uI e from Figure 1 e. 20 Bolm Inst. oceanogr., S Paulo, 28(2), 1979 NaupZius VI (Fig. lf) term; exopod, 1:1:1:1:1 + 3 ; mandible, Length = 0.20 mm (5 specimens), 0.21 mm as in the stage V. Maxillule (Fig. (4 specimens) and 0.22 mm (1 specimen). in~, basi~od'12l+ ls; lobe I, 3 + 2 term; Body shape similar to stage IV and segmen- o e 11, + ong termo tation more pronounced than in the pre-ceding stage (Fig. 16). Labrum like in stage V, although with tufts of setules 011 the anterior margin. The terminal spines Fig. 16. Nauplius VI, O. oligohalina, 0.20 mm. of the caudal armature are longer than the lateral setae. Presence of two more small setae laterally to the two pairs of lateral setae, one on each side of the body. Antennule (Fig. 2l), 0:1:1:1 long and thick, 8 lateral setae + 4 or 5 termo Antenna (Fig. 2m), coxopod, 2s + 1; basipod, 2; endopod, 2 + 3 Fig. U. Naupl ius VI, antennule from Figure 16. Fig. 2m. Nauplius VI, antenna from Figure 16· Fig. 2n. Nauplius VI, maxillule from Figure 16· Discussion The naupliar stages of O.ov~ and O. oligohalina are similar but some small morphological difference existo These small details make the two.species recog-nizable since the first stage of develop-ment. The nauplii of O. oligohilina are larger than those of O. ov~ described by Bjornberg (1968, 1972) and Fanta (1976) . The present material a] 5 0 s hows the c.;e differences 1n size of the two s pecies (Tab le I): The body shape of the O. oligohaLi.na is oval and that of the O. ova~ 1S more rounded. The stage IV, V and VI of both species differs in many aspects, es-pecially the structure of the caudal armature: the terminal spines which are placed between the two pairs of lateral terminal setae of O. oligohilina are longer than those of O. ov~. Table 11 lists the differences for each stage of both species. SimiZarities among nauplii of the genus Odhona Gibbons & Ogilvie (1932-33), after Ramamohana Rao (1958), have shown the taxonomic value of the labrum structure for the identification of the nauplii of the genus Odhona and that the caudal armature is useful for the identification of the different stages of each species. Bjornberg (1972) establishes two evolutive lines among the species of O~ona. The first includes O~hona .6 .úr~_~, O. nana and O. ovo;e..-W and O. tntmda, the second O. plwrú..6Vta and O. h~lgolandi~a. The author adds that O. ~nuta probably is the most primitive form due to its unspeciallized caudal armature and because the simplicity of the setal appendages. The species O. nctna follows and could have evoluted to O. ov~ in estuarine waters and t o O. ptwrú..6~~ in oceanic waters. O. oligo-halina can be added to the O. ov~ group. The lack of intermediate forms among the naupliar stages of both species con-firms the validity of O oligohaLLna and O. ov~. The two species were found to FONSECA & PRADO: O. oligohalina: naupliar development 21 Table I - Length (mm) of the naupl iar stages of O,Lthona ova1..-L6 and O. oligohalina O-i.t:ho na o va,Ull O-i.t:hona ova!-i.ll O-i.t:ho na crva!ü OUhona. oUgo ha.Una. Naupllus 11 111 IV V VI Naup l j us I Naupl i u s 11 (after Bjornberg, 0.091 and O .081 O . 100 to 0 . 110 O . 11 5 and 0.110 O . 124 and O .125 O . 11 5 and O • 140 O . 145 to 0.185 Oi.t hDna ovat-i.6 AI - 0 : 0 : 1:3 A I - O : O : 2 : 3+tuf t o f set ul es A2 - cx, ls+\ s t i bs , 2 : en ,2+2 or 3; ex, I : 3 : 3 Nau pl i u s 11 1 Al - 0 :1: 2 :3 +3 te r mo Md - cX jb s,2; en . 3 :3; e x. 45,O : I : I :2 Na u p l ju s IV Labru m w i th o ut med i u m pr o tub e ran ce i n ant e -r io r mar gin. Nauplius V Naupl ius VI A2 - cx ,2 ; b s,2; e n, 2 t e r m+2je x , 5S, I : I : I : I : I : 2 Mx - I b I (25, sh ort , AI A, -Md Mx I t + l o n9 ) , I b I I (25 s hort , d i s tal+ I I o n9) . O: O : l+l t h+l l o n g a nd t hi c k: 5+4 t erm ex. 25; b 5 , 2 ; en, 2 t e r m+ 2; ex, 6 5, I : I : I : I : I : 2 ex , 55 b 5 , I ; I b I ( 2+ I t e r m I on9) ; I b 1I ( 2 + I te r m lon9) A 2. - cx,2s+1 ar 2; bs, 2; en,2term+ 2l t , ex, I: I : I : I : 3 Md ex, 55 Mx - bS,2 + 1s: lb I, 2+3tel""m; lb l l, 2 + llong 1968) (after Fanta, 0.0883 O . 1076 O .1230 0.1346 O .1551 O . 1735 Oi.tho na oligo hali. na A I O: O: I : 2 Al O:I:2:3+tuft of setules A2 - cx, ls+l st ; b s , 2 ; en,2+2 j e x , O : 3+ 3 AI 0: 1 :2:3 +4 te r m o Md - cx; b s, 2 ; en.3 : 4 ; e x ,4S , 0 : 1:1 : 2 La b ru m with me dium p ro -tuberanc e i n the a n te-ri or ma rg in . A2 ex , 2 s , b s , 2; en , 2+ 3 ter miex , 55, 1 :1:1 : 1 ·:2" Mx - Ib I d ,s It+2 ), lb 11 (2s s h or t, d ista i + I l on g ) A I O: I : I : I ( l o n g a nd t h i ek) : 6 +4 t e rm. A, - ex, 25 ; bs,2;en, 2+ 3 t e r m; ex, 6S , I : I : I : I : I : 2 Md ex, 4 5 Mx bs.,O; l b I O +l term I on9) ; I b 1I ( 2 + I ter m l o n9) A, - ex, 2 s + 1 ;b s, 2 ; en ,Z+ 3 term, ex , 1 : 1 : 1 : 1 : 1 + 3 Md - ex , 4 5 Mx - bs , 2 + 1 5 ; I b I , 3+ 2 t e r m; 1 b li, 2 + I te r m long ~ wo 5ma!! setae between the Two 5mal! l atera l a nd A I en It ex tWQ te r minal spines of the a n te ri o r se t ae t o the caudal armatu r e. tWQ pairso f t h e t erm i-n a ! setae of the caudal armat u re. antennulle; bs - basipod; lb - l obe; A2 - a ntenna ; endopod; st - setae; Md - mandible; ex - exopod; lateral; Mx - maxillu l e; 5 - spine; th - thin ; coxopod; S - segment; term - terminal 1976) (after Fonseca, 1976) (after Fonseca, 1976) 0.094 O • 11 O • 114 O . 13 O .122 O .13 O . 14 O .137 O . 1 5 O .16 O . 153 0 . 17 0 . 18 0.179 0 . 20 O .22 Tab 1 e I I - Morpho 1 og i ca 1 compar i son between naupliar stages of Oithona ova1..-L6 and O. oligohalina and t o to to occur simultaneously within a small sa-linity range in the Cananeia region (Fonseca, 1976). Acknowledgment Special thanks are due to Dra. Tagea K. S. Bjornberg for helpful suggestion and criticism of the manuscript. Bibl iography BJ~RNBERG, T. K. S. 1968. Estágios de desenvolvimento de alguns copepodos marinhos planctônicos tropicais e sub-tropicais. Tese de Livre Docência. Universidade de são Paulo, Fac. Fil. Ciênc. Letr., l7Sp. 1972. Developmental stages of some tropical and subtropi-cal planktonic marine copepods. Stud. Fauna Curaçao, 40:l-l8S. FANTA, E. S. 1976. Anatomy of the nauplii of Oithona ov~ Herbst CCopepoda, Cyclopoida). Bolm Zool., Univ. S Paulo, 7:20S-238. FONSECA, V. L. 1976. Copepodos do gene-ro oithona da região de Cananeia (Lat. 2S 0 07'S., Long. 47°S6'W). Dissertação de Mestrado. Universidade de são Pau-lo, Instituto Oceanográfico, 68p. 22 Bolm Inst. oceanogr., S Paulo, 28(2), 1979 FONSECA,V.L. & BJ~RNBERG, T.K.S. 1976. O~ona oligohalina sp. n. de Cananeia (Est. de são Paulo) e considerações so-bre O~ona ov~ Herbst (Copepoda, Cyc10poida). Anais Acad. bras. Ciênc., 47:127-131. RAMAMOHANA RAO, V. 1958. Deve10pment of a cyc10poid O~ona JU.g.úia (Giesbrecht) . Andhra Univ. Mem. Oceanogr., 2:128-131. SANTOS, J. J. 1970. P1âncton da Baía de Todos os Santos, com especial referên-cia aos copepodos. Disserta~ão de Mestrado. Universidade de Sao Paulo, Instituto de Biociências, 49p. (Recebido em 27/dezembro/1977) 

The naupliar development of Oithona oligohalina, Fonseca & Björnberg, 1976

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