Santos-Silva-et-al-1999-Neotropical-genus-Notodiaptomus.pdf

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Stud Neotrop Fauna & Environm (1999) Vol. 34: 114–128 0165-0521/99/3402-0114$15.00© Swets & Zeitlinger

Address correspondence to: E.N. Santos-Silva, Coorde-nação de Pesquisas em Biologia Aquática, Instituto Na-

cional de Pesquisas da Amazônia, C.P. 478, 69011-970,Manaus, AM, Brasil. E-mail: [email protected]

INTRODUCTION

The genus Notodiaptomus Kiefer, 1936 is the mostwidely distributed and most species rich genus of

freshwater calanoids in the Neotropics. In 1983 Dus-sart and Defaye listed 28 species in this genus; thenumber of nominal species is currently 39. As withmost diaptomids, species have been erected mainlyon morphological details of adult , with particu-

lar emphasis on the sexually dimorphic characters of the leg 5, right antennule and the posterior part of theprosome. Except for a few recently described spe-

cies, little attention has been given to . Descrip-tions are very variable regarding the level of detailprovided in the text as well as in the quality of illus-trations. This makes identification very difficult. The

aim of this paper is to provide a thorough redescrip-tion to modern standards of accuracy, of the type-species Notodiaptomus deitersi (Poppe, 1891), toimprove knowledge of the genus and to enhance un-derstanding of the distribution of this poorly charac-

terized species.

MATERIALS AND METHODS

The specimens were collected in the Baia Pedra Bran-ca (15o52′19′′S, 56o08′35′′W), a locality in the vicin-ity of Cuiabá, Mato Grosso, Brazil.

THE NEOTROPICAL GENUS N OTODIAPTOMUS KIEFER, 1936(CALANOIDA: DIAPTOMIDAE): REDESCRIPTION OF THE TYPE

SPECIES N OTODIAPTOMUS DEITERSI (POPPE, 1891) AND

DESIGNATION OF A NEOTYPE

Edinaldo N. Santos-Silva1,2, Geoff A. Boxshall2 and Carlos E.F. Rocha3

1Department of Aquatic Biology, INPA, Manaus, Brazil2Department of Zoology, The Natural History Museum, London, England

3Department of Zoology, USP, São Paulo, Brazil

ABSTRACT

Notodiaptomus Kiefer, 1936 is the most abundant and speciose genus of freshwater calanoids in the Neotropicalregion. The type species, N. deitersi (Poppe, 1891) is in need of redescription but the type material is no longerextant and the type locality no longer exists. In order to avoid possible confusion over the identity of the type speciesof the genus, a neotype is designated. This is an adult from Baia Pedra Branca because this locality is near Cuiabá,in the State of Mato Grosso, Brazil, the original type locality. The neotype is described and this description formsthe basis for a complete diagnosis of the genus Notodiaptomus. Like most diaptomid genera Notodiaptomus is

characterized by prosome morphology, by the fifth legs in both sexes and by the geniculate antennule. Sexualdimorphism in the rostrum is reported here and the homology of the modified setal elements on the geniculate rightantennule of the is analysed.

KEYWORDS: Notodiaptomus deitersi, neotype, taxonomy, Calanoida, freshwater, Mato Grosso, Brazil.


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115REDESCRIPTION OF N OTODIAPTOMUS DEITERSI

Samples were taken using a plankton net (55 µmmesh), concentrated and fixed in the field with 6%formalin. Specimens were examined whole or dis-

sected as temporary preparations mounted in lac-tophenol. Pieces of broken coverslips were used toprevent compression by the coverslip. Observationswere made using a differential interference contrastmicroscope (Olympus BH-2) and all drawings weremade with the aid of camera lucida. All measure-ments were made with an ocular micrometer. Addi-tional preparations were made for SEM studies (Phil-lips XL-30), following the protocol used byFelgenhauer (1987) and Huys and Boxshall (1991).The specimens were washed several times in dis-

tilled water, dehydrated through graded acetone andcritical-point dried. Samples were mounted on stubsand coated with gold or gold-palladium.

Neotype: dissected on 20 slides and depositedin the INPA (INPA – CR 550a-t) was selected fromlarger sample of and from Baia Pedra Bran-ca. Additional material from the same locality and

date: 1 adult dissected on 20 slides (INPA – CR551a-t) and 231 (INPA – CR 552) and 57 (INPA - CR 676) in alcohol; 20 and 20 inthe MZUSP (MZUSP – 12.823); 20 and 20 in the NHM-London (NHM 1998.2389 and1998.2398); 20 and 20 in the MNHM –Paris (MNHN-Cp1685); 20 and 20 in theUSNM – Washington, DC (USNM 243686).

Abbreviations used in the text: INPA-CR-Institu-to Nacional de Pesquisas da Amazônia, Seção Crus-tacea, Manaus; MZUSP-Museu de Zoologia da Uni-versidade de São Paulo, São Paulo; NHM-TheNatural History Museum, London; MNHM-MuséumNational d’Histoire Naturelle, Paris; USNM-Nation-al Museum of Natural History, Washington, DC;

SEM-Scanning Electron Microscope; s-seta; ae-aes-

thetasc; cs-conical seta; vs-vestigial seta; ms-modi-fied seta; p-process; N-number of actual segments;A-ancestral segments.

RESULTS

Notodiaptomus deitersi (Poppe, 1891)

Neotype

An adult ; Baia Pedra Branca (15o52′19′′S,56o08′35′′W), Mato Grosso, Brazil, in the vicinity of Cuiabá, the original type locality. The description is

supplemented by the examination of additional ma-terial, including , from the same locality.

Description

Length of neotype: excluding caudal setae: 1100 µm,(mean length 1098 µm ( N =20), standard deviation(SD)±27.6). Body (Fig.1A) smaller and more slenderthan . Rostrum (Fig. 5D) with paired rostral fila-ments; asymmetrical with process on right side of basal region; defined from frontal margin of dorsalcephalic shield by complete suture; ornamented withpair of sensillae adjacent to suture. Cephalosomewith incomplete suture dorsally. Fifth free pediger-ous somite with small and more or less symmetrical

lateral wings, each with small sensilla at apex (Fig.1A). In dorsal view, body widest at first free pediger-ous somite (Fig. 1A). Sensillae distributed on pro-somal somites as figured (Fig. 1A).

Urosome: (Fig. 1A) 5-segmented. Genital somitesymmetrical with one sensilla at right posterior cor-ner and another on left side inserted more medially

than on right. Genital aperture at ventrolateral poste-rior corner of genital somite on left side. Anal somitewith weak operculum; two sensillae on each side(Fig. 1A). Caudal rami symmetrical, longer thanwide, with 6 setae; setules along medial margin.

Right antennule: 22-segmented (Fig. 2A–D); seg-ments 13 to 18 (XV to XX) swollen and modified.Segmentation pattern and setal armature presented inTable 2. On segments 17 and 18 (XIX, XX), one of those setal elements is probably a seta-like aes-thetasc; on segment 20 (XXIV–XXV), two setae areinserted posteriorly; on 21 (XXVI), one is insertedventrally. Vestigial setae on segments 2 (III), 3 (V)and 5 (VII) comprising circle of thin cuticle andminute seta at centre of circle. Tips of large setae on

segments 3, 7, 9 and 14 blunt (Fig. 2B, see arrow-

heads). Seta on segment 19 very small (Fig. 2C).Modified setae on segments 10 and 11 similar to eachother but different from those on segments 13, 17, 18and 19 (Fig. 2C, D). Modified seta forming strongprocess on segment 13 (Figs. 2D, 8A). Modified se-tae on segments 17, 18 and 19 similar (Fig. 2C, seearrowheads). Segments 15 and 16 each with spinousprocess on frontal margin (Figs. 2B, D).

Left antennule: 25-segmented (Fig. 3A, B); onlysecond and last segments compound, representing theancestral segments II–IV and XXVII–XXVIII re-spectively, armature of segments presented in Table2. Insertion of one of those setae is posterior on seg-


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116 E.N. SANTOS-SILVA ET AL.

Fig. 1. Notodiaptomus deitersi neotype, adult : A, habitus, dorsal. Adult : B, habitus, dorsal.

ments 22 and 23 (XXIV, XXV), and ventral on seg-ment 24. Tips of large setae on segments 3, 7, 9 and14 blunt, as in right antennule (Fig. 3A). Segmenta-tion and armature pattern different between right and

left antennules. Both with compound second (II–IV)

and last segments (XXVII–XXVIII). Right antennulewith additional fusions: segments 19 and 20 repre-senting ancestral segments XXI–XXIII and XXIV–XXV respectively. Armature pattern differing with

segments 13 and 15 of left antennule lacking aes-


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Fig. 2. Notodiaptomus deitersi neotype, adult : A, right antennule, detail of last segment (ancestral XXVII–XXVIII); B, right anten-nule, ventral, arrowheads indicate blunt setae or, on proximal segments, vestigial setae; C, right antennule, detail of segments 17,18 and 19 (ancestral segments XIX, XX and XXI–XXIII respectively), anterior, arrowheads indicate modified elements around

geniculation; D, right antennule, detail of segments 10-16 (ancestral segments XII–XVII), ventral, arrowheads indicate spinuousprocesses, and extra aesthetascs not present on left antennule.


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Fig. 3. Notodiaptomus deitersi neotype, adult : left antennule

drawn in two sections as indicated by asterisks, A, seg-ments 1–17 (ancestral segments I–XIX), anterior; B, seg-ments 18–25 (ancestral segments XX–XXVII), anterior.Blunt setae, conical setae and vestigial setae are indicatedby arrowheads.

thetascs and segments 13 to 18 each lacking proxi-mal seta. Modified setae present on segments 10, 11,13, 17, 18 and 19 unmodified in left antennule.Smooth hyaline membrane present anteriorly on seg-

ment 20. Antenna: biramous (Figs. 5E, 6A). Coxa bearing

inner seta. Basis with two setae at posterior inner

corner. Endopod 2-segmented (Fig. 5E): first seg-ment with two setae on inner margin, ornamentedwith oblique row of spinules on outer side and pore

between row of spinules and setae; compound sec-ond segment bilobed; inner lobe bearing 8 setae dis-tally, outer lobe with 7 distal setae and patch of spinules on outer margin. Exopod 7-segmented (Fig.6A), segmentation and armature pattern: segment 1(ancestral segment I), 1 seta (s); segment 2 (ancestralsegments II–IV), 3 s; segment 3 (V), 1 s; segment 4(VI), 1 s; segment 5 (VII), 1 s; segment 6 (VIII), 1 s;segment 7 (ancestral segments IX-X), 4 s (distal partderived from segment X elongate, bearing 3 long api-cal setae).

Mandible: (Figs. 7C, E, F) with strongly sclero-tized coxal gnathobase carrying prominent lobe oncaudal margin (Fig. 7E); cutting blade with acutecaudal and triangular subcaudal teeth, and group of 6multicusped teeth, apicalmost bearing spinules, ad-ditional row of spinules present on dorsal side; singledorsal seta located near apical margin (Fig. 7F). Man-

dibular palp (Fig. 7C) with basis bearing four setaeon inner margin, three inserted more distally. Endo-pod 2-segmented; first segment with lobe bearingfour setae; second with 9 distal setae (one reduced),and two rows of spinules. Exopod 4-segmented with1, 1, 1, 3 setal formula.

Maxillule: (Fig. 6B, C, D) with praecoxal arthritecarrying 10 stout marginal spines, plus five sub-mar-ginally (four of them more slender), ornamentationcomprising patch of spinules present sub-marginally(Fig. 6C). Coxal epipodite with 9 setae. Coxal enditewith 4 distal setae. Basal exite represented by outerseta. Proximal basal endite well defined, bearing 4setae distally. Distal endite fused to basis, with 4setae and row of marginal spinules. Endopod 1-seg-

mented and bilobate: proximal lobe with 3 setae on

margin, distal lobe with 5 setae (Fig. 6D). Exopodunsegmented, with 5 distal setae and row of spinuleson margin (Fig. 6D).

Maxilla: (Fig. 7A) with praecoxa and coxa medi-ally fused, but separate laterally. Proximal praecoxalendite with 5 setae and one small spine; distal enditebearing 3 setae and row of spinules. Coxal enditeseach carrying 3 setae plus row of spinules on distalmargin. Allobasis well developed, armed with 3 se-tae. Three free endopod segments bearing 5 setae intotal.

Maxilliped : (Fig. 5B) well developed, comprisingsyncoxa, basis and six free endopod segments. Prae-


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Fig. 4. Notodiaptomus deitersi neotype, adult : A, left first leg, posterior; B, left second leg, posterior; C, left third leg, posterior; D,third exopod segment of third leg, anterior; E, third endopod segment of third leg, anterior; F, third exopod segment of second

leg, anterior; G, third endopod segment of second leg, anterior; H, first and second segments of second leg endopod showingSchmeil’s organ, lateral.


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Fig. 6. Notodiaptomus deitersi neotype, adult

: A, right antenna exopod; B, right maxillule; C, detail of right maxillule arthrite; D,detail of right maxillule endopod and exopod. Adult : E, left fifth leg, posterior; F, fifth leg, detail of endopod.


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Fig. 7. Notodiaptomus deitersi neotype, adult : A, right maxilla; B, fifth leg, posterior. Arrowheads indicate: patch of tubercles on leftbasis; patch of tubercles and outgrowth with a deep groove on right basis; acute outgrowth on first exopod segment. C, palp of right mandible; D, detail of right fifth leg endopod and groove, posterior; E, right coxal gnathobase of mandible with cuttingblade; F, detail of right mandible cutting blade; G, detail of left fifth leg endopod and exopod segments, posterior.


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coxal endite with one seta and row of spinules. Coxalendites represented by 8 setae in 3 groups on medialmargin: setal formula 2, 3, 3 plus patches of spinules

each; distal inner angle of syncoxa produced intorounded lobe with setules around margin. Basis with3 setae on medial margin and subterminal rows of spinules on one side and setules on other. Endopod6-segmented; first segment reduced, setal formula: 2,3, 2, 1 + 1, 4.

Swimming legs: (Figs. 4A–H, 5A, F, G) biramouswith 3-segmented rami, except endopod 2-segment-ed in leg 1: legs scarcely ornamented except by set-ule rows along outer and inner margins of endopodalsegments; legs 2–4 with distal row of spines on ante-

rior surface of third exopod and two rows on thirdendopod (Figs. 4D-G, 5F, G). Schmeil’s organpresent on posterior surface of second endopodal seg-ment of leg 2 (Fig. 4H). Outer seta present on poste-rior surface of basis of leg 4 (Fig. 5A). Spine and setaformula as follows:

spinules along inner margin; endopodal lobe withcomb of spinules on inner anterior surface.

Left fifth leg: (Fig. 7B, G, 8D) not reaching right

first exopod segment; coxa with small conical proc-ess posteriorly, and triangular sensilla at outer distalcorner: basis with seta on outer margin, inner marginslightly concave, ornamented with patch of tuber-cles. Exopod 2-segmented; first segment sub-trian-gular, outer margin curved, inner margin with semi-circular outgrowth bearing long setules; secondsegment ending in heavily chitinized digitiform proc-ess; inner margin with curved process carrying set-ules on margin and spinulose seta inserted distally onanterior surface; anterior surface concave with patch

of spinules. Endopod 1-segmented, conical, with rowof spinules on inner distal margin.

Adult

Length: excluding caudal setae: 1125 µm, (meanlength 1148 µm ( N =20), SD±28.5). Body (Fig. 1B)larger than . Rostrum (Fig. 5C) broader than in ;symmetrical; with pair of sensillae at incompleteproximal suture. Cephalosome with incomplete su-ture dorsally. Fifth free pedigerous somite symmetri-cal, with curved posterolateral wings, each with sen-silla at tip (Fig. 1B). In dorsal view, body widest atfirst free pedigerous somite (Fig. 1B). Sensillae dis-tributed on prosomal somites as figured (Fig.1B).

Urosome: (Fig. 1B) 3-segmented. Dorsal: genitaldouble-somite nearly symmetrical, longer than othersomites together, swollen in anterior region with twosensillae, one on each side; right posterior cornerexpanded over next somite. Second urosomite small,right and left posterior corners expanded laterally.Anal somite with weakly developed operculum with

two sensillae on each side. Caudal rami symmetrical,

with setules along inner margin. External genital area(Fig. 5H) ventral: delimited anteriorly by broad sym-metrical opercular pad, and laterally by well devel-oped, posteriorly-directed lateral processes. Pairedgonoporal plates and slits located adjacent to mid-line, between lateral processes. Extensive area of rel-atively flexible cuticle (arthrodial membrane?),present anterior to opercular pad.

Antennules: symmetrical; similar to left anten-nule (Table 2). All other appendages as in exceptleg 5. Leg 5 (Fig. 6E, F) symmetrical; coxa withconical posterior process in distal left corner withtriangular sensilla at tip; basis sub-triangular, outer

TABLE 1. Notodiaptomus deitersi, neotype . Spine and seta-formula.

Coxa Basis Exopod Endopod

Leg 1 0–1 0–0 I–1; 0–1; I,I,4 0-1; 1,2,3

Leg 2 0–1 0–0 I–1; I–1; I,I,5 0–1, 0–2; 2,2,3Leg 3 0–1 0–0 I–1; I–1; I,I,5 0–1; 0–2;2,2,3Leg 4 0–1 1–0 I–1; I–1; I,I,5 0–1; 0–2; 2,2,3

Fifth legs: asymmetrical (Fig. 7B, D, G, 8C, D).Right fifth leg (Fig. 7B, 8C, D) with rudimentarypraecoxa present; coxa with conical process directedposteriorly and projecting over basis, process withslender sensilla on tip. Basis with outgrowth on pos-terior surface and with deep oblique groove reachingendopodal lobe, groove finely ornamented with

minute tubercles along its edges (Fig. 7D); inner mar-gin with semicircular lamella covered with fine tu-bercles extending onto adjacent segment surface; se-tae on outer margin inserted anteriorly; distal innercorner bearing endopodal lobe. Exopod 2-segment-ed; first exopod segment with acute sclerotized out-growth posteriorly on distal margin projecting oversecond exopod segment; distal outer corner produced

into triangular outgrowth; second segment withcurved ridge on posterior surface, lateral spine locat-ed in distal quarter of segment, row of spinules oninner margin. Claw inserted distally, strong andcurved proximally, slightly curved distally with


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Fig. 8. Notodiaptomus deitersi neotype, adult , SEM pictures: A, detail of modified seta forming strong process on segment 13(ancestral segment XV); B, detail of the segments around the geniculation of the right antennule, arrows indicate the modifiedelements; C, fifth leg, detail of the right endopod; D, fifth leg, lateral, arrows indicate the tip of the left endopod, the outgrowthin the posterior surface of the left basis and the deep oblique groove.

margin smaller than inner margin with long seta ex-

tending beyond distal margin of first exopod; firstexopod segment larger than second; second segment

with lateral spine; distinct third exopod segment withtwo terminal setae, lateral smaller, not reaching be-yond middle of medial. Terminal claw with medialand lateral rows of denticles. Endopod 1-segmentedbearing two setae on oblique tip plus row of spinessubterminally on anterior surface.

Remarks

Notodiaptomus deitersi (Poppe, 1891), was brieflydescribed by Poppe. It is possible that there has been

some confusion with subsequent identification of

Notodiaptomus deitersi. This species was recorded

from Lake Parnagua, Piaui in the northeastern Brazilby Spandl (1926), and from the lakes Recreio and Sá

Mariana, Mato Grosso, Brazil by Matsumura-Tundisi(1986); from Paraguay by Lowndes (1934) and fromArgentina by Brehm (1959), Ringuelet and Martinezde Ferrato (1967). The material reported by Lowndes,Brehm and Matsumura-Tundisi differs in some char-acters from Notodiaptomus deitersi sensu Poppe,1891 as described by Spandl (1926).

The only feature clearly figured by Poppe (1891)in the original description, that we can not confirm inthe material examined, is the presence of 2-segment-

ed endopod in leg 5 of the . We have observed a


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discontinuity in the cuticle of the inner margin of theendopod which presumably indicates the plane of fu-sion of the endopod segments. All other features de-

scribed by Poppe (1891) are present in the specimensobserved.

Some authors, when reporting on material identi-fied as N. deitersi (Poppe, 1891), have presented de-scriptions that match Poppe’s in most details (Spandl,1926) but others report features that differ fromPoppe’s (1891) original description. Lowndes(1934), studying material from Paraguay, drew at-tention to the “pyramidal projection” on the penulti-mate somite of the body which was covered withminute spinules, to the presence of hyaline membrane

on the antepenultimate segment of the right anten-nule, and to a spine (treated here as conical setae) aslong as those on segments 10 and 11. He also foundthat the had a 2-segmented endopod in the fifthleg. Brehm (1959) noted several features that agreewith Lowndes (1934), but he didn’t observe the py-ramidal projection in the penultimate somite of thebody, only a patch of spinules. He reported a semi-circular membrane on the basis of right fifth leg of and also a strongly chitinized region in the distalinner margin of the second exopod segment of thesame leg. It is remarkable that Brehm stated that thespecimens observed by him are closely related to N.venezolanus. Ringuelet and Martinez de Ferrato(1967) also found the pyramidal projection coveredby spinules on the fourth somite of the body and 2-segmented endopod in the fifth leg. Matsumura-Tundisi (1986) figured the pyramidal projection onthe fourth prosomal somite covered by spinules,but found no hyaline lamella or process on the ante-penultimate segment of the right antennule. Theendopod of the fifth leg was 1-segmented.

Given this degree of inconsistency in morphologi-

cal accounts of N. deitersi we consider that it is pre-mature to summarise existing distribution records.Only the examination of material previously identi-fied as N. deitersi will provide verification that theseidentifications match Poppe’s description (1891) andthe neotype designation presented here.

Notodiaptomus Kiefer, 1936

Diagnosis

Diaptomidae, Diaptominae. and appendagessimilar except right antennule and leg 5. Rostrumsexually dimorphic. and left antennule 25-seg-

mented, exhibiting similar segmentation pattern (allancestral segments expressed except II–IV andXXVII–XXVIII) and setal armature; lacking aes-

thetascs on segments 13 and 15 (XV and XVII) andsetae on segments 13 to 18 (XV–XX) present in .

and antennules with vestigial setae on ancestralsegments III, V and VII; large setae on segments 3,7, 9 and 14 (V, IX, XI and XVI) each with blunt tip;conical setae on segments 8 and 12 (X and XIV).Antenna endopod 2-segmented; first segment withoblique row of spinules and conspicuous pore: exo-pod 7-segmented; segments 2 and 7 representing an-cestral segments II–V and IX–X respectively. Swim-ming legs poorly ornamented, biramous with

3-segmented rami, except endopod 2-segmented inleg 1; legs 1–4 with lateral spine on each exopodsegment, except leg 1 lacking spine on exopod seg-ment 2; legs 2–4 ornamented with distal row of spinules on anterior surface of third exopod and tworows on third endopod segment. Schmeil’s organpresent on posterior surface of second endopod seg-

ment of leg 2. Leg 4 with seta on posterior surface of basis. : cephalosome with incomplete suture dor-sally; rostrum asymmetrical with process on rightside of basal region; nearly symmetrical lateral wingson fifth free pedigerous somite; urosome 5-segment-ed; caudal rami symmetrical, longer than wide, withsetules along medial margin; right antennule modi-fied, 22-segmented; segmentation pattern (ancestralsegments expressed except II–IV, XXI–XXII,XXIV–XXV and XXVII–XXVIII) and setal arma-ture of segments different from left and anten-nules (Table 2). On segments 17 and 18 (XIX, XX),one of those setae is probably a seta-like aesthetasc;on segment 20 (XXIV–XXV), two setae are insertedposteriorly; on segment 21 (XXVI), one seta inserted

ventrally; segments 13 to 18 (XV to XX) swollen and

modified; small spinous processes present on seg-ments 15 and 16 (XVII and XVIII); conical setaeasE; modified setae on segments 10, 11, 13, 17, 18and 19 (XII, XIII, XV, XIX, XX and XXI); verysmall setae on segment 19 (XXII); modified setae onsegments 10, 11 and 13 forming processes, that on 13stronger and more robust than those on segments 10and 11; modified setae on segments 17, 18 and 19 aresimilar among them, but differing from those on seg-ments 10 and 11. One of those 2 setal elements onsegments 17 and 18 is probably a seta-like aesthetasc.Left antennule 25-segmented; second and last seg-ments compound; armature is presented in Table 2.


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One of those setae on segments 22 and 23 (XXV) isinserted posteriorly, and ventrally on segment 24;lacking aesthetasc on segments 13 and 15.

Fifth leg asymmetrical; rudimentary praecoxapresent; coxa with conical process projecting overbasis with slender sensilla on tip; outgrowth on poste-rior basal surface with deep oblique groove orna-mented with minute tubercles along edge; semicircu-lar lamella on inner margin of basis covered with finetubercles extending onto adjacent segment surface;

endopodal lobe on inner corner of basis. Exopod 2-segmented; acute sclerotized outgrowth present ondistal margin of first exopod segment and distal cor-ner produced into triangular outgrowth; second seg-ment with curved ridge on posterior surface, lateralspine in distal third of segment; claw strong andcurved proximally, with row of spinules along innermargin. Endopodal lobe with comb of spinules on in-ner anterior surface. Left fifth leg; coxa with conicalprocess posteriorly with triangular sensilla on apex;inner margin of basis with patch of tubercles. larger than ; all appendages, except leg 5 and

right antennule, as in ; rostrum broad, symmetrical

without process on basal region; symmetrical lateralwings on fifth free pedigerous somite; urosome 3-segmented; genital double-somite inflated anteriorlyand nearly symmetrical; anal somite with weakly de-veloped operculum; caudal rami symmetrical with

setules along inner margin; external genital area withprominent lateral processes on opercular pad; anten-nules symmetrical 25-segmented similar to left an-tennule of ; leg 5 symmetrical, coxa with conicalprocess with sensilla at tip, basis subtriangular with

long setae reaching beyond distal margin of first exo-pod, first exopod segment larger than second, secondwith lateral spine, distinct third exopod segmentsmall, with two terminal setae, lateral smaller; termi-nal claw with denticles on medial and lateral mar-gins, endopod 1-segmented with two setae and ob-lique comb of spines subterminally on anteriorsurface.

Remarks

The genus Notodiaptomus was established by Kiefer(1936) to accommodate eleven species originallyplaced in Diaptomus Westwood, 1836 sensu lato.

TABLE 2. Segmentation pattern and armature of antennules in the genus Notodiaptomus Kiefer, 1936 based primarily on the typespecies but including known interspecific variation within the genus. A, ancestral segments; N, number of actual segments;s, seta; ae, aesthetasc; vs, vestigial seta; ms, modified seta; p, process. (*) shows the armature observed in the neotype.

A N right antennule N left antennule antennules

I 1 1s+1ae 1 1s+1ae 1s+1aeIIIIIIV 2 3s,1ae,1vs 2 3s,1ae,1vs 3s,1ae,1vsV 3 1s,1vs 3 1s,1vs 1s,1vsVI 4 1s 4 1s 1sVII 5 1s,1ae,1vs 5 1s,1ae,1vs 1s,1ae,1vsVIII 6 1s 6 1s 1sIX 7 1s,1ae 7 1s,1ae 1s,1aeX 8 1s,1cs 8 1s,1cs 1s,1csXI 9 2s,1ae 9 2s,1ae 2s,1aeXII 10 1s,1ms 10 1s 1sXIII 11 1s,1ms 11 1(*) or 2s 1 or 2sXIV 12 1s,1ae,1cs 12 1s,1ae,1cs 1s,1ae,1csXV 13 1s,1ae,1ms 13 1s 1sXVI 14 2s,1ae 14 1s,1ae 1s,1aeXVII 15 2s,1ae,1p 15 1s 1sXVIII 16 2s,1ae,1p 16 1s,1ae 1s,1aeXIX 17 1 or 2s(*),1ms 17 1s 1sXX 18 2s,1ms 18 1s 1sXXI 19 1s,1ae 1s,1aeXXII 20 1s 1sXXIII 19 2s,1ae,2ms 21 1s 1sXXIV 22 2s 2sXXV 20 4s 23 2s 2sXXVI 21 2s 24 2s 2sXXVIIXXVIII 22 4s,1ae 25 4s,1ae 4s,1ae


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Four of these species, Notodiaptomus nordestinus(Wright, 1935), N. henseni (Dahl, 1894), N. iheringi(Wright, 1935) and N. deitersi (Poppe, 1891) had

previously been considered part of nordestinus-groupcreated by Wright (1935); the other seven added byKiefer (1936) were N. amazonicus (Wright, 1935),

N. cearensis (Wright, 1936), N. santaremensis(Wright, 1927), N. carteri (Lowndes, 1934), N. ani-sitsi (Daday, 1905), N. incompositus (Brian, 1925)and N. inflatus (Kiefer, 1933). Kiefer did not providea formal diagnosis to the new genus but groupedthese species on the basis of the following features:– the nature of the final segment of the left exopod

of the fifth leg;

– the geniculate antennule carried conspicuousspines on segments 10, 11, 13, 14 and 16, whichwere very similar in all species;

– the antepenultimate segment of the geniculateantennule is ornamented with, at most, one hya-line membrane.

Kiefer (1936) considered the nature of the left exo-

pod on the fifth leg to be the most significantcharacter.

Kiefer did not designate a type species for thegenus Notodiaptomus. In the absence of an originaldesignation there has been some confusion aboutthe type of the genus. Ringuelet (1958) formallydesignated Diaptomus deitersi Poppe, 1891 as the“genotype” of the genus Notodiaptomus. Under theInternational Code of Zoological Nomenclature thissubsequent designation is valid. Then, Dussart &Defaye (1983) proposed that “par souci de priorité,c’est N. gibber (Poppe, 1889) qui pourrait être prisecomme espèce-type”. But Diaptomus gibber wastransferred to Notodiaptomus by Pallares in 1963,several years after the creation of the genus, and was

not originally included in Notodiaptomus by Kiefer

(1936). Consequently, following Article 67(g) of theCode it can not be accepted as the type of the genus.So, the designation by Ringuelet (1958) of Diaptomusdeitersi as type species of the genus Notodiaptomus isvalid.

DISCUSSION

Sexual dimorphism in the rostrum of calanoid copep-ods has been observed and figured by many otherauthors. In the family Aetideidae, for instance, thereare extreme examples of this sexual dimorphism; in

Batheuchaeta Brodsky, 1950 for example, has therostrum well developed in , but absent in (Markhaseva, 1996). In the family Diaptomidae some

authors have noted or figured the dimorphic rostra.Brandorff (1973), Dussart & Robertson (1984), Reid(1985), Reddy (1994) and Santos-Silva et al. (1996),for example, all figured differences in and ros-tra but didn’t discuss the significance of this. It ap-pears that this dimorphism may be widespread in thefamily since it is known in Notodiaptomus and Mas-tigodiaptomus Light, 1939 (Santos-Silva et al., 1996)and in Neodiaptomus Kiefer, 1932, ArctodiaptomusKiefer, 1932 and Sinodiaptomus Kiefer, 1932 (Red-dy, 1994). The extent of expression of this sexual

dimorphism across the genera of the family Diapto-midae, remains to be established.

The geniculate right antennule of diaptomidsprovides many characters of taxonomic importanceat both specific and generic levels. The modifica-tions of setal elements on the segments either side of the geniculation (Fig. 2C) are probably highly con-

served and of little significance, since they corre-spond closely to modifications known in other cala-noid families. These may be deep rooted calanoidcharacters. Similarly, the 10 proximal segments ap-pear highly conserved and all species of Notodiap-tomus thus far studied exhibit identical setation, in-cluding the possession of the three vestigial setae(Santos-Silva, unpublished). The most informativesection of the right antennule lies between seg-ments 10 (XII) and 16 (XVIII) (Fig. 2D). Setal ele-ments are modified on segments 10, 11 and 13, andthe precise apomorphic form of each element can beimportant. Segments 15 (XVII) and 16 (XVIII) havenovel spinous processes on the frontal margin; theirpresence and relative size can be important. The form

of the long setae on segments 3(V), 7(IX), 9(XI) and

14(XVI) may also be significant since the apex ap-pears to be strongly rounded in some species of Noto-diaptomus.

Preliminary studies of six Notodiaptomus specieshave revealed that the basic setal formula of the and left antennule is identical to that of N. deitersi ,with one exception. Segment 11 (XIII) commonlycarries one seta only, as in N. deitersi, but in somecongeners, such as N. amazonicus (Wright, 1935) and

N. cearensis (Wright, 1936), two setae are present.The loss of the proximal seta on this segment may bea useful apomorphy in phylogenetic analysis of Noto-diaptomus, and even other genera of Diaptomidae.


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ACKNOWLEDGEMENTS

This research has been supported by CAPES and PDEE

grant BEX0290/98-0. We are grateful to Rony Huys for hisguidance in drawing techniques and for numerous discus-sions; to Danielle Defaye (Muséum National d’HistoireNaturelle, Paris) for her comments on genital structuresand on the manuscript; to Alex Ball and Chris Jones fromthe Electron Microscope Unit/The Natural History Muse-um for their assistance and; to Vangil Pinto da Silva fromthe University of Mato Grosso who kindly collected andprovided the material.

REFERENCES

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Dussart BH, Defaye D (1983): Répertoire mondial desCrustacés Copépodes des eaux intérieures. I. Ca-lanoïdes. Edit. CNRS. Bordeaux/Paris, 224 pp.

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Received: 12 October 1998Accepted: 24 November 1998

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