— Bijdragen tot de Dierkunde, 52 (2): 103-120 19Ô2
The chaetotaxy of Cypridacea (Crustacea, Ostrocoda) limbs:
proposals for a descriptive model
by
Nico W. Broodbakker
Institute of Taxonomie Zoology, University of Amsterdam,
P.O. Box 20125, 1000 HC Amsterdam, The Netherlands
&
Dan L. Danielopol
Limnological Institute, Austrian Academy of Sciences,
Gaisberg 116, A-5310 Mondsee, Austria
Abstract On souligne l’importance des recherches sur le développe-
ment dans le but d’établir des homologies au niveau de la
The need for better and more of systematic descriptions chétotaxie.
the data the struc- chaetotaxy (especially concerning shape, Des exemples de morphologie fonctionnelle des setae sont and of distribution of ture pattern the setae) is emphasized. analysés, et on arrive à la conclusion que la morphologie The historical of studies in developments chaetotaxy are de celles-ci être fonctionnelle de la majeure partie peut mieux reviewed. étude de dont les comprise par l’organe entier setae sont Two of cuticular be basic types processes can recognized: Une seulement une partie constitutive. signification adaptive setae and The former have sensorial and pseudochaetae. n’est le de les setae. pas propre toutes mechanical functions, the latter mechanical only a function. On modèle de la chétotaxie des propose un descriptif A of is special type seta the aesthetasc or the chemosenso- des Ostracodes Cypridacés. Les diverses particularités setae, rial Using the and structure of the setae, receptor. shape ainsi que leur position sur les extrémités, sont codés par
most of them can be classified in the following categories: lettres et chiffres, avec utilisation de formules simples. simple, plumed, serrate and chelate.
The importance of developmental studies for the estab- lishment of homologies in chaetotaxy is stressed. INTRODUCTION of functional Examples morphology of setae are discussed.
It is emphasized that the functional morphology of most The of the be better understood when the whole superfamily is one of the setae can organ Cypridacea groups is studied of in the which the setae are only a component. Not all most rich species of Ostracoda which suc-
the setae have an adaptive significance. cessfully inhabits the limnic environment. The A descriptive model of the chaetotaxy of cypridacean ostracod and the soft covered ostracods is presented. The different characteristics of the carapace body are
setae as well as their position on the limbs are coded by with diverse setae like hairs, claws and specialized letters and numerals using simple formulae. chemosensorial organs.
of the the The pattern distribution of setae on
Résumé organism is generally called chaetotaxy (Ken-
In this this in neth, 1976). paper we use term On souligne la nécessité d’une description meilleure et plus connection with studies basic systématique de la chétotaxie, ceci s’appliquant surtout à the of two types of à la des l’aspect et structure setae, ainsi qu’au modèle de cuticular ostracod processes that cover the soft leur distribution. On de manière chronolo- passe en revue body: the setae and the pseudochaetae (see section gique les développements des recherches sur la chétotaxie. and Il est de reconnaître deux "Basic nomenclature" for the possible types fondamentaux morphology d’appendices cuticulaires: les setae et les pseudochaetae. Les The definition of these structures). present study premières remplissent des fonctions sensorielles et mécaniques, deals with the the classification and tandis morphology, que les autres ont seulement une fonction mécanique. of ou the distribution of the of L’aesthétasque, récepteur chémo-sensoriel, représente un pattern specific types type spécial de seta. Tenant compte de l’aspect et de la struc- cuticular processes mentioned above. la de celles-ci ture des setae, plupart peuvent être rangées ostracod The investigation of chaetotaxy is use- dans les catégories suivantes: simples, plumeuses, denticulées ful other in order et à aspect de chela. among things to accurately
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define the taxonomie position of the organism, to TOWARDS BETTER DESCRIPTIONS OF
CHAETOTAXY obtain information on the way of life of the animal
in affinities and to get insight the phylogenetic Besides the positive achievements mentioned of with other ostracod taxa. Due to this large area still of ostracod seta- above, very poor descriptions interest it is understandable that zoologists con- tion of W. Klie are being published. Many papers centrated on the description of the chaetotaxy ever suffer from this deficiency (e.g. Klie, 1941). since the early stages of ostracod investigations. Some authors figure indiscriminately bristles that the of After a review of historical developments for are irrelevant, instance Paulo (1969: 28, fig. chaetotaxy research in cypridacean ostracods, the 10) in his description of the chaetotaxy of the need for better and more systematic descriptions maxilla. This negative situation occurs mainly A basic is emphasized in the present paper. nomen- because there is not enough information about the clature and a descriptive model is proposed and functional and developmental characteristics of the arguments are exemplified with an analysis the of ostracods. Neither there setae many are of developmental and functional morphology of enough data to recognize homologies and anal- some of the setae and pseudochaetae of Cypridacea. the ogies between setae, nor are differences be-
tween setae and pseudochaetae well understood. HISTORICAL DEVELOPMENTS The ostracodologists working on carapace
morphology found it useful to standardize the The study of cypridacean chaetotaxy started at the terminology in order to improve the descriptive beginning of the nineteenth century, incorporated data different reviews (for see: Hartmann, 1966; in the general study of freshwater ostracods. The
& Benson, 1971; the Sylvester-Bradley Keyser, 1980). description of setae during this period was the of the limbs, Da- and Considering chaetotaxy not very well defined mostly inaccurate, see nielopol & Cvetkov (1979) proposed a system e.g. the descriptions of Liljeborg (1853) or those of description of the setae using letters and of Vejdovsky (1882). In order to document this numerals. A less has been used the developed system statement, a plate of "Dictionnaire des scien- by Shornikov (1980). The advantage of such a ces naturelles" edited by Frédéric Cuvier in the consists in of between 1804 and is here system a more complete description years 1830, reproduced the limbs in form. the setation of an abridged It in 1. On this one can fig. plate recognize repre- also allows the retrieval of data for computer sentatives of the subfamilies Candoninae, Cypri- storage and treatment because of the symbolized dinae and Notodromatinae of which the setae are language used. only approximately figured.
In the a basic nomenclature for the It the end following was during of the last century and setae of cypridacean limbs and a descriptive model the beginning of the present one that zoologists for the will be It will be started in chaetotaxy proposed. to represent ostracod limbs an accurate demonstrated that the The understanding development way. most significant contributions are those and their of the setae functional purpose (if any) of Müller (19OO) and Sars (1925). During the
is a to the of the last wide prerequisite improve knowledge fifty years a range of aspects has been chaetotaxy of ostracods. investigated in relation to the chaetotaxy of the
Cypridacea: contributions on general morphology of setae using light and electronmicroscope tech- BASIC MORPHOLOGY AND niques (Rome, 1947; Triebel, 1961; Danielopol, NOMENCLATURE 1972, 1973; Andersson, 1975; etc.), on functional
morphology (Cannon, 1926; Storch, 1926), on The term seta comes from the latin seta which
chaetotaxy classification for taxonomy (De Deck- means bristle or hair; the greek equivalent is
and for chaeta A is ker, 1979; Maddocks, 1976, 1979) (Kenneth, 1976). seta, as an organ,
reconstruction cuticular conical phylogenetic (Danielopol, 1976, a process, normally or tubular,
in the 1978). most of cases articulated at a socket on the
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illustrated in “Dictionnaire sciences naturelles” edited Frédéric Desmarest was Fig. 1. Ostracods des by Cuvier; respon-
a of article “Malacostracés ”) and for the on sible for the text on ostracods (published in 1823, being part his plates
work is The valve and of ostracod crustaceans in this (published 1816-1830; plate 55 reproduced here). carapace shape
well with those of 3 with and no. 7 with Notodromatinae. The no. 1 conform Candoninae, no. Cypridinae Cypridinae
the second instead of the Candoninae The of the (no. 2) should have swimming setae on antenna, (no. 1). chaetotaxy
2 recalls which first endopodal segment of the second antenna of ostracod no. some “giant” pseudochaetae, are imaginary all minute because European freshwater Cypridinae have pseudochaetae.
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in limb, having an inner lumen which nervous markedly developed (fig. 2E). The surface of
cells The and the is in increased terminate. seta plays a sensory seta most cases largely (Danielo-
mechanical role and the is (Rome, 1947). pol, 1972) innervation very complex
A defined seta, as above, is a morphological (Andersson, 1975).
character which not be subdivided Another of cuticular is the can logically type process
further but can be expressed in a variety of forms pseudochaeta (figs. 28, F). This is a tiny
like: thin hairs, feathered bristles, clawlike struc- cuticular production having no basal articulation
The various of has tures, etc. expressions morphologi- and no inner lumen; it is not innervated and
cal characters called are character states (Crovello, only a mechanical function. Rome (1947) de-
the 1970; Stevens, 1980). The setae generally have scribed fine structure of a pseudochaeta when
a proximal shaft separated from the distal one by delineating the morphology of the walking legs
his an annulation (fig. 2A). The external morphol- (see plate V figs. 44-45). The main role of
of the setae differs sclero- the is adhesion of micro- ogy widely. Heavily pseudochaetae to prevent
tized setae form clawlike or chelate setae (hard- particles on the ostracod limbs (see for example
ened, curved processes). In ostracods most of the Danielopol, 1978, fig. 25). Exceptionally, in the
setae thin and flexible. of the terrestrial Meso- are case ostracods of the genus
The setae can be ornamented with tiny setules, cypris, some of the pseudochaetae play a protec-
denticles or scales. Most of the ostracod setae tive role preventing the desiccation of the soft
look like those of other & basically crustacean groups body (Danielopol Betsch, 1980).
data (for decapod see: Thomas, 1970; Farmer,
1974; Drach & Jacques, 1977). In the following DEVELOPMENTAL ASPECTS several description terms are adopted from deca-
literature pod (viz., simple setae, plumed setae, One central of the problems in the study of chae- serrate, plumose, pappose, pseudochaeta). totaxy is the recognition of similarities between
When the distal shaft of the seta is smooth, it different setae due to inheritance from a common
will be called seta. Most simple of the ancestor. that of Jardine (1969) suggested one
setae are covered with setules. When the setules the most effective criteria for identifying such flexible are and have a hairy the is the appearance, homologies correspondence in relative posi- setae said are to be plumed setae ( fig. In tion. ostracods one of the problems is that in When 2A). the setules are or toothlike spiky order to understand the relative position of the
are called serrate they setae (fig. 2G). it is to obtain information setae, necessary on how The plumed setae can be divided into plumose these structures develop. In some cases the setae when the setules are disposed on one or morphogenesis of the ostracod limbs happens
two rows the distal shaft along (fig. and within in it 2C), one juvenile stage, while other cases when pappose setae the setules arise on happens sequentially during several developmen- all sides of the shaft (fig. 2D). The chelate setae tal stages (Van Morkhoven, 1962). An example be smooth can or serrate. of the first case is the development of the pincer Some special setae can be easily recognized complex (cleaning organ) of the second thoracic from their morphology and/or Danielo- in position. leg Cypridacea. In Herpetocypris chevreuxi pol (1970, 1972, 1978), & McKenzie O. Danielopol (G. Sars) this complex comes into being just (1977) and Danielopol & Cvetkov used (1979) before the moulting of the sixth juvenile instar such for setae a of letters and symbolic system (figs. 3A, C, D). However, the setation of the numerals. For instance some setae of the mandibu- antennula and antenna develops sequentially lar have been called seta and palp a, ß (Danie- several From y during moult stages. one stage to lopol & McKenzie, 1977). another the setae can change their morphology A second major type of seta is the aesthetasc. their and sometimes position on the limb (Danie- This is a specialized seta with a chemosensorial lopol, 1970, 1978, 1982). The distal shaft of this receptor. of seta is The is of the in type following an example way
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Fig. 2. Details of the chaetotaxy of the second antenna in Cypridacea: A, D, F, G, Pseudocandona delamarei Danielopol
(Sauve, Gard, France); B, Ilyocypris bradyi (Sars) (Lake Caldarusani, Romania); C, Cryptocandona sp. (Volp, Ariège,
Mixtacandona with France); E, sp. (Cuhea, Maramures, Romania); (A, D, G, male; B, C, E, F, female). A, exopodite annulated with distal t and of setae, one plumed (X 5655); B, endopodite z setae (X 870); C, plumose seta protopodite
of aesthetasc Y of endo- (X 10440); D, pappose seta first endopodite (X 20880); E, (X 19140); F, pseudochaeta first
of (X 4872); G, claw G note the strong serration this seta (X 9570). podal segment M ,
Downloaded from Brill.com10/05/2021 01:32:27PM via free access of the second thoracic the and the of chevreuxi Fig. 3. A-D, Development leg, pincer organ chaetotaxy Herpetocypris
(Sars) (isle of Majorca, Spain), female: A-C, sixth instar, D, adult; E-H, Details of the endopodal chaetotaxy of the second
Pseudocandona zsckokkei baikal- antenna: E-F, (Wolf) (Rhône valley, Lyon area, France), G-H, Pseudocandona inaequivalvis ensis Bronstein (Baikal Lake); (E, G, male; F, H, female). The black triangle indicates the undeveloped articulation be-
third tween the second and endopodal segments.
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which it with a developmental study of the chaetotaxy and z setae, but presents a dimorphism
can to solve the of to the claw G help problem phylogenetic respect 3 .
the affinities between two geographically isolated Considering common morphological type
ostracod species: Pseudocandona zschokkei of the Candoninae, for example the second an-
(Wolf), a groundwater ostracod from western tenna in Ps. serbani (fig. 4), it can be noticed
baikal- Europe, and Pseudocandona inaequivalvis that the t and z setae develop sequentially, starting
sixth ensis Bronstein from Lake Baikal. at the instar. After each moult a new seta
it be and in the adult male Before discussing this problem should comes into being two setae
remembered that most of the Candoninae have and t their (t2 3 ) change morphology drastically
second The male its sexually dimorphic antennae. and one z seta changes position from the
has antenna a four-segmented endopodite and lateral to the medial side.
two t while the female Ps. strongly developed setae, Taking the development of serbani as a
has antenna a three-segmented endopodite and "normal" or standard type, it can be inferred that undifferentiated t setae (e.g. in Pseudocandona the antennae of Ps. zschokkei and Ps. inaequival-
serbani vis show Danielopol, 1982, see figs. 4C, D). baikalensis a paedomorphic aspect. The The discovery of Candona insculpta Müller, t setae of the adult male Ps. zschokkei correspond
without these dimorphic characters (both sexes to the eighth instar chaetotaxy of Ps. serbani
have and undif- and a three-segmented endopodite the z setae in Ps. zschokkei have a pat- Kaufmann ferentiated t setae) prompted (1900) tern typical of the seventh instar of "normal" Can-
to erect Pseudocandona. Most of In of a new genus, doninae. the case Ps. inaequivalvis baikalen-
the Candoninae remained sis dimorphic grouped the development of the chaetotaxy stopped
in during Kaufmann's time the genera Candona, shortly before sexual differentiation in the last
Cryptocandona and Candonopsis. Other Pseudo- phase of the eighth instar.
candona Kaufmann have been dis- species sensu These data, added to other morphological dif-
covered in zschokkei ferences in the and Zenker Europe [Ps. (Wolf, 1919)] hemipenis organ struc- and in Asia in Lake Baikal [several species (Bron- tures, convinced Colin & Danielopol (in litt.) 1939, This last stein, 1947)]. author, considering that the European groundwater Candoninae (e.g.:
the similarities the morphological of second an- Ps. zschokkei) ) are not phylogenetically closely
the and Baikal tenna of European species, con- related to the Baikal Candoninae. With this
cludes that Ps. zschokkei is related to the Baikal example we stress the necessity of studying
the Candoninae. According to Bronstein (1939) thoroughly the developmental aspects of the chae-
origin of these species should be found in an Old totaxy of Cypridacea. Tertiary, widely distributed Candoninae fauna,
that was found in the whole Palaearctis. A re- examination of the species allowed Colin & Danie- FUNCTIONAL MORPHOLOGY
demonstrate that the lopol (in litt.) to two groups
related and that the A are not phylogenetically genus better description of the chaetotaxy in cyprida-
Pseudocandona as defined Kaufmann is by a cean ostracods creates the opportunity to question
taxon. A redefinition of this the of such polyphyletic genus purpose morphological structures or
has been Functional published by Danielopol (1978). patterns. morphology will help to examination of zschokkei At a close Ps. (figs. identify analogies between setae and to distinguish it be that the second is between 3E, F), can seen antenna analogical and homological characters,
The female has four t setae in sexually dimorphic. important phylogenetic research as it is possible
located the and two z setae on lateral side, while to reconstruct of evolutionary pathways some three and the male has t setae two z in this only setae, cyprideacean groups manner (cf. Riedl, which is the medial one of located on side of the 1978).
baikalensis endopodite. Ps. inaequivalvis (figs. In the sequel, several aspects of the adaptive
has 3G, H) no dimorphism with respect to the t problem of the chaetotaxy in two cypridacean
Downloaded from Brill.com10/05/2021 01:32:27PM via free access 4. Pseudocandona second details of the chaeto- Fig. serbani Danielopol, 1982 (Jiblea, Vilcea, Romania), antenna, endopodal taxy: A, seventh instar; B, eighth instar; C-D, adults (C, female, D, male). Downloaded from Brill.com10/05/2021 01:32:27PM via free access TOT DE DIERKUNDE, 52 - 1982 BIJDRAGEN (2) 111
ostracods, Notodromas persica Gurney and Her- complex. The right distal endopodite has, besides
its petocypris chevreuxi (Sars) are discussed. the distal seta, on surface two sclerified
lamellae also A definition of adaptation is provided by (fig. 5B) which can play a tactile
Lewontin is the of role. The left has on the (1978): "Adaptation process endopodite proximal
which hooks and the distal evolutionary change by the organism pro- segment two large on segment
sclerified that vides a better and better 'solution' to the 'prob- an irregular strip (fig. 5F). Note
and distal like lem* the end result is the state of being the left endopodite has no seta most
adapted". According to Williams ( 1966), Lewon- of the cypridacean ostracods. Considering the
tin and to evaluate evolution of the male maxillar ( 1978) Jaksic ( 1981 ), one way global endopodites
the adaptive value of morphological structures is in order to evaluate the tactile function, it is
to view them through engineering analyses. noticeable that some of the morphological struc-
tures, like the distal seta and the sclerified lamellae
The setae as isolated organs of the right palp, are well developed, while other
The right endopodite of the maxilla in the male structures disappeared completely (the left distal
of Notodromas persica has on its distal segment seta) and some remain in the form of vestigial
elements a long seta, with one row of setules (figs. 5A, C). (the proximal minute setae).
is male touches the Its function tactile, the the female In the case of Notodromas persica specific
have noticed information transmitted the female during mating. Similar cases been tactile is to
in representatives of the Candoninae (Danielopol, through the highly specialized structures mentioned 1980). In the Candoninae the endopodite of the above. A related species, N. monacha (O. F. Mül-
male maxilla touches the female in the early phases ler), has developed a completely different set of of mating, in order to stimulate the reaction of morphological characters in order to transmit
"sexual acceptance". sensorial information (Petkovski, 1959). Refer-
The proximal endopodite segments of the male ring back to the minute setae of the proximal endo-
maxillae in N. persica bear two minute setae (figs. podal segment in the male of N. persica, within
The seta the maxilla is the framework of an tactile structure 5A, D, F). on right pap- integrated
that left is smooth. The it inferred that their pose, while on the one can be functional importance
function of these minute setae remains uncertain is reduced. The differences between the right
when isolated It is minute seta and the left smooth they are regarded as organs. pappose one may
certain that not they play a positive tactile role be due to the different genetic constraints under
during mating activity. In the Candoninae, where which those two structures developed.
the distal setae are reduced to hyaline smooth tips, A second example will be provided regarding
the proximal endopodal setae are long and well the chaetotaxy of the "pincer complex" (cleaning
sclerified, for instance the maxillary palps in the organ) of the second thoracic leg of Herpeto-
male of Candona dancaui Danielopol (Danielo- cypris chevreuxi (fig. 3D). In this species the
pol, 1978, figs. 8E, F). Both the and formations M, and M which relate proximal pseudochaetal 2 ,
distal these the the setae of palps play a tactile role directly to pincer complex, are better developed
in the Candoninae. (larger and the pseudochaetae are longer) than
the series M and M which are pseudochaetal 3 4 , Chaetotaxy as of an structural part integrated located far from the pincer. Several other adapta-
complex increase tions are present in order to the cleaning
Gould & Lewontin (1979) and Gould (1980) function of this leg, viz., a strongly bent and ser- showed function that the structure and/or of many rate distal seta, the denticulate beak-shaped distal
characters better understood and morphological can be endopodal segment a concave lobe, finely within the framework of an integrated structural haired, that developed from the subterminal endo-
When the male maxillar of Two setae, and complex. endopodites podal segment. endopodal pz , pz2 ,
Notodromas examined reduced role the persica (figs. 5 A-G) are are very and obviously play no in
it is clear their is as a whole, that morphology mechanical activities of the pincer.
Downloaded from Brill.com10/05/2021 01:32:27PM via free access Fig. 5. Notodromas persica Gurney (Lake Caldarusani, Romania), male: A-D, right maxilla; E-G, left maxilla: B, distal endopodal segment, arrows indicate the sclerified lamellae; C, distal endopodal seta; D, minute seta of the first endopodal
distal the left of distal of segment; F, part of endopodite, note the minute simple seta the first segment; G, chaetotaxy the maxillar and the distal of endite. protopodite unique exopodal seta; H, maxillule, seta the first
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the Its Chaetotaxy and basic functional adaptations water movement through carapace. only
adaptive function could be a sensorial one; how- In some cases the pattern of setal distribution on evidence there is no intuitive or empirical of the ever, the ostracod limbs is the result adaptation for this function. of the animal to special environmental situations.
A in is the of the maxillar case point chaetotaxy From the data in this chapter it is concluded that of Notodromas The Notodro- protopodite species. the the functional morphology of chaetotaxy can animals on the fine matinae are neustonic feeding if the whole is be better understood organ studied,
that occur on the surface of the water, particles of because the setae are only a component it. feed bottom while most of the cypridaceans on
the substrates. Besides the adaptation of carapace THE DESCRIPTIVE MODEL to enable this surface feeding activity (see morphological details in Müller, 1900) there are This descriptive model treats the chaetotaxy of also diverse morphological changes in the struc- the different limbs. The model uses abbreviations ture of the second antenna, the mandibular palp, the for the different segments of limbs, together the maxillular endites and the maxillar protopo- with the position, the number, the type, length have distribu- dites. The last mentioned an unusual setulation the and eventually or barbulation of i.e. tion pattern of the distal setae, they are disposed setae on the segments. The list of abbreviations each sclerified frame in two rows, placed on a (fig. and symbols used in this system is provided in and and short. In most 5G) they are pappose table I. of the cypridacean ostracods the setae of the
The — All segments. segments are repre- in maxillar protopodite are inserted one row, on numerals. The sented by letters and roman letters the unsclerified distal margin and they are also used abbreviations of the names of the are seg- but than in Notodromas. If these pappose longer ments, while the segment number is indicated by function in adaptations are accepted to have a the a roman numeral. Most encountered are: endo- gathering of fine food particles from the surface podite (E), exopodite (Exo) and protopodite and bringing them to the mouth, then these adap- in (Pr). The other abbreviations are provided solution in tations constitute a good engineering table I. order to increase the brushing efficiency of the The length of the segments is measured from limbs and to gather widely dispersed particles articulation to articulation. If this is not possible thin the surface. It distributed as a layer on water because the articulations are not clearly demarcated, is the more difficult to explain peculiar shape the length is measured by drawing lines at both of the distal setae on the maxillular endite ends of the segments and measuring the distance (fig. 5H). between the 7D. centres of these lines, as in fig.
The position of the setae. — The
Not all setae have an adaptive function setae can have different positions on the limbs,
the the It should be stressed that even well-developed also depending on orientation of limb
have lost their former main itself the animal. So when lies in the setae may apparently on the limb function. For instance the of the maxil- the axis and the chaetotaxy same plain as body carapace hinge, lar in ostracods is the orientation be anterior exopodite many cypridacean can (A), posterior (P),
in lateral When the is considered to play a significant role moving (L) or distal (D). limb more
within the In the less the water carapace space. case or at right angles to the main body we use of Notodromas persica the maxillar exopodite is interior (In) and exterior (Ex), instead of ante-
inserted and presented as a unique seta, directly on the rior posterior. protopodite (fig. 5E). Most cypridacean bottom The length of the setae. — The length
have six inserted small will of dwellers setae on a exopo- of the setae be related to the length a
the of the dal segment (fig. 7C). Obviously unique seta segment respective limb, in a way as ex-
in For of N. persica can not play a significant role the plained in table II. example, if a seta of
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Table I
used Symbols in the chaetotaxy system.
General
A anterior I to VII 1st to 7th segment Mxu maxillula
A 1 antennule In interior Mxup maxillular palp
A 2 antenna 2 L lateral P posterior
chelate CS seta / long pa pappose
D distal M medial Pr protopodite medium E endopodite m pi plumed
Ex exterior Mastic masticatory process pu plumose
Exo exopodite Max maxilla s small
Fu furca Md mandible ser serrate
G claw Mdp mandibular palp T 1 (2) thoracopod 1 (2)
Special setae, aesthetascs, etc.
setae of the viz. at E I: E II: In and E III: «, ß, y special Mdp, In, P, respectively Max: Pr: A a two setae at
b smooth seta at Max: Pr: Ex
CL beaklike claw at T 2: E IV: D
d plumed seta at Max: Pr: Ex
G G anterior and posterior claw of Fu a> p G minor and major claws at A 2: E IV m> G„
GI interior-anterior claw at A 2: E III
GÎ exterior-anterior claw at A 2: E III
Gs exterior-posterior claw at A 2: E III
Lo lobe at T 2: E III: D-In
small T 2: E III: D-In pzi seta at
T E IV: D pZ2 seta at 2:
R ramus
Rome's A II: P r organ at 1:
s s anterior and seta of Fu a> p posterior
Si, S2 plumed cleaning setae at Mdp: E I: In
tl to t4 four setae with different orientation in different species and in males and females,
of 2: III: not always present, in most the cases at A E A-P
Y aesthetasc at A 2: E I: P
aesthetasc A VII: D )'a of 1:
three if A E III: E P-D and E IV: P-D yi to Y3 aesthetascs, present at 2, viz., P, III, respectively
Z1 to Z3 three setae of A 2, with varying orientation depending on species and sex, in
the somewhere E and most of cases distally at III, near Gi G2
if the antennule (A 1 ) is shorter than or as long hairy appearance are called plumed (pi), and as the third endopodal segment (E III), it is possible plumose (pu) when the setules are dis- called small When it is than but in the distal (s). longer once, posed two rows along shaft, or pap- shorter than or twice the third when the setules arise all sides of as long as endopo- pose (pa) on dal segment, it is called medium (m). When it is the shaft (figs. 2A, C, D).
Setae with longer than twice the third endopodal segment spiny or toothlike ornamentation it is called long (/). This is done for each seta, will be called serrate (ser). Chelate setae will be
it with the comparing corresponding segment of called as such (cs); in the special case that they
in of claw its limb as shown table II. have the form a claw they will be called
Types of setae. — As mentioned in the (G) (after the French "griffe"). This last type
this preceding part of paper there are different of seta can be smooth or serrate with one ( 1 ser )
of Setae setules and types setae. with flexible a or two rows of spikes (2ser).
Downloaded from Brill.com10/05/2021 01:32:27PM via free access 52 - 1982 115 BIJDRAGEN TOT DE DIERKUNDE, (2)
Table II
of of the with their The evaluation the length setae as compared corresponding
limbs.
Abbreviation Segment used Relative length of setae (se) reference of limb as Small (,r) Medium (m) Large (!)
A 1 E III <1 1 < se 2 >2
A E I 1 1 2 l/2 < se < >
Mdp E III < 1 1 < se < 2 > 2
Mxu Mxup II < 2 2 < se < 3 >3
Max Lateral < 1 1 < se 2 >2
margin
protopodite
T 1 E II < 1 1 < se < 2 >2
E I 1 T 2 1/2 < se < >1
V: VI: Some special setae which can be recognized A-2/, P-ls-lm/ A-2/, P-2// A-D-2/, P-2//
from their and/or are dis- VII: -lm-2l. morphology position D-y a
criminated letters and in this by a symbolic system of The paper of Broodbakker (1982) same
de Dierkunde" will numerals (Danielopol, 1970, 1972, 1978; Danie- issue of "Bijdragen tot serve
of the this lopol & McKenzie, 1977; Danielopol & Cvetkov, as a good example use of system.
1979). The aesthetascs (specialized setae with a
chemosensorial also have receptor) names repre- DESCRIPTION OF THE LIMBS sented and these by letters numerals. Part of sym- bol systems will be adapted here, as will be men- Antennule (A 1). — At the posterior
the of the different limbs. border of the second there is tioned at description segment a sensory
The — First the abbreviation of the which is called "Rome's This system. organ organ" (r).
of the limb is followed the have various forms or it be absent. name provided by organ can may
the and In it is almost flush abbreviation of name number of the Heterocypris margaritae with
respective segment and the description of the the segment and not easily recognizable (fig. 6A).
setation of this For for The other of this limb with segment. example antenna only organ a special
two: A 2: Pr: ../Exo: .../E I II ...etc. name is the antennular aesthetasc at the distal . .../E a y ,
The end the seventh name of the segment is followed by a of segment (according to Danie-
position where setae are present, which position lopol, 1978).
is followed again by the number and length of Antenna 2 (A 2). This limb can have
the this and the the setae at position so on for other four aesthetascs. One relatively large one at
interior positions if more setae are present. For example: surface of the first endopodite, Y, which
A IV: be in 1: .../E A-2/, P-ls-lm/. ..etc. can very large hypogean species (Danielo-
Special setae will also be named after the The which is not present in H. length pol, 1978). y x ,
is in given, and aesthetascs will only be named. For margaritae, can be present other species (fig.
A 2: .../E + -2/ at the interior side of the third example: (II III): (?) D-y 2 4), endopodite
P- ...etc. near the second At the interodistal (z 1 ,22 )-lw(z3)-3w(G 1,G2,G3 :2ser), endopodite.
(fig. 6C). side of this we also find while can segment y2 , y3
As will the a complete example we provide the be found at interodistal side of the fourth
the antennule male Hetero- chaetotaxy of of a endopodite (figs. 4, 6).
cypris margaritae Margalef (cf. fig. 6A): A 1: I: The three claws at the distal side of E III or
and II: A-l.r/ III: IV: E + are called G G G and the A-U, P-2/(pi)/ A-1j, P-1j/ (II III) 1; 2 3
Downloaded from Brill.com10/05/2021 01:32:27PM via free access Fig. 6. Heterocypris margaritae Margalef (Bonaire, Caribbean): A, antennule (A 1); B, second antenna (A 2); C, detail of second antenna; (A-B, male; C, female).
Downloaded from Brill.com10/05/2021 01:32:27PM via free access BIJDRAGEN TOT DE DIERKUNDE, 52 (2) - 1982 117
two claws of E IV are called G and G which also carries a small The fourth M (major) m seta, pzj.
claw (minor), according to Danielopol (1972, 1973, segment presents a beaklike (CL), which is
1978) (figs. 4, 6). At the interior and/or exterior serrate at the top, with behind it another small
side of E III E + also find two On the end of the also a or (II III) we seta, pz 2 . segment larger,
rows of setae, the t and z setae. These setae can curved, serrate seta is borne ( fig. 3D ).
be short the orientation be different The is of or long, can pincer organ a specialized adaptation
in and between male and It different species even the Cypridinae. is weakly developed in the
female of the same species. Sometimes not all of Notodromatinae and absent in the Candoninae.
the is these setae are present. The maximum is three In Pontocypridinae the structure totally
with of 2 setae and four t setae like in the female of H. different, two chelate setae (one which
is and A margaritae (fig. 6C). Some of the variability in strongly serrate) a detritus lobe. detailed
the orientation and shape of these setae is shown descripton of these and other types of distal parts
in fig. 4. of this leg can be found in Danielopol (1978).
Furca — The furca terminates — with Mandibular palp (Mdp) . There are (Fu). two
and three setae the that different claws, an anterior one a one on palp are clearly (Ga ) posterior
from the the and at the intero- it also bears two setae, one anterior rest, a, ß y setae, (Gp ); (sa ) and distal borders of the I and and at one In this we segments II, posterior (sp ) (fig. 7F). adopt the the exterodistal border of segment III, respectively, nomenclature of Danielopol & Betsch ( 1980).
as shown in fig. 7A. Furthermore there are two
plumed setae, probably with a cleaning function, CONCLUSIONS the at interior border of the first segment. They
are called Si and S The names for other setae Isaac Levi in his "The 2 . (1980) essay enterprise of as used in Danielopol (1978) will not be used knowledge", emphasizes that scientific com-
in this munities their three differ- paper. modify knowledge by
— The Maxillula. maxillula does not present ent processes: expansion, contraction and replace-
any specially named setae. ment. Thoughtful observations and better descrip-
Maxilla — There be tions of ostracod will (Max). can two small the chaetotaxy of limbs
setae at the anterior margin of the protopodite, certainly expand our understanding of the biology
the setae and evolution of these animals. The of the a, one plumose seta near the masti- usage
the catory process, seta d, and one seta posterior model of chaetotaxy description proposed here
of will d, the seta b (fig. 7C) (Danielopol & McKen- help to contract, but not to eliminate, the
zie, 1977). information which is not immediately of interest
Thoracopod 1 (T 1). — The first thoracic to the ostracod student. This contracted informa-
does not tion can later be if leg present any specially named setae. activated, necessary, by its in Thoracopod 2 (T 2). — The cleaning leg incorporation comparative descriptive models.
has several special structures and pseudochaetal Finally, the obligation to improve the examination
formations mentioned in of the will as the preceding part of chaetotaxy bring new insights and new
this and paper shown in fig. 3D. The structure concepts on various matters of ostracod research,
of the distal be best which should part of this leg can explained replace our present state of know-
in writing and with a detailed illustration instead ledge.
of series a of abbreviations, as in the rest of
this leg. ACKNOWLEDGEMENTS
Most a Cypridinae present pincer organ at the The initial impetus for the preparation of this distal of the The paper came part leg. pincer organ has from Dr. B. Scharf who asked (Mainz), D. L. Danielopol to developed from the end of the third and the provide a synthetic system of description for the cypridacean fourth The endopodal segments. interodistal side chaetotaxy.
One of of the third us (D. L. Danielopol) communicated with Dr. W. segment has developed into a hairy Thomas and Dr. (London) F. Jacques (Banyuls) on various lobe (Lo), forming the lower half of the pincers, of He received topics crustacean chaetotaxy. financial support
Downloaded from Brill.com10/05/2021 01:32:27PM via free access 7. male: mandibular maxillula C, Fig. Heterocypris m argaritae Margalef (Bonaire, Caribbean), A, palp (Mdp); B, (Mxu); furca maxilla (Max); D, thoracopod one (T 1); E, thoracopod two (T 2); F, (Fu).
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"Verband der E. Trois nouvelles for preparing this report from the Wissen- DANIELOPOL, D. L. & CVETKOV, 1979.
schaftlichen Gesellschaften Österreichs" (Vienna). Prof. H. espèces du genre Mixtacandona (Ostracoda, Cyprididae,
Löffler provided the Baikal ostracods figured here. Dr. T. Candoninae). Hydrobiologia, 67: 249-266.
Andrew of read first draft D. L. & K. G. 1977. (New University Ulster) kindly a DANIELOPOL, MCKENZIE, Psychrodro-
of this commented Prof. Ostracoda), with paper, which was further on by mus gen. n. (Crustacea, redescription
of the and J. H. Stock (Amsterdam) and Prof. H. Löffler (Vienna). cypridid genera Prionocypris Ilyodromus.
The other author (N. W. Broodbakker) is financed by the Zoologica Scr., 6: 301-322.
Evaluation of features distinctive Netherlands Foundation for the Advancement of Tropical DECKKER, P. DE, 1979. above Research (WOTRO), The Hague. in the taxonomy of the Cypridacea, the generic
level. In: N. KRSTIC ed., Taxonomy, biostratigraphy and
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Received: 30 June 1982
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