RETROGRESSUS (COPEPODA, ) FROM IRRIGATION AND DRAINAGE DITCHES OF THE RHÔNE DELTA (CAMARGUE, FRANCE) A REDESCRIPTION W Mielke

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W Mielke. CLETOCAMPTUS RETROGRESSUS (COPEPODA, HARPACTICOIDA) FROM IR- RIGATION AND DRAINAGE DITCHES OF THE RHÔNE DELTA (CAMARGUE, FRANCE) A REDESCRIPTION. Vie et Milieu / Life & Environment, Observatoire Océanologique - Laboratoire Arago, 2001, pp.1-9. ￿hal-03192074￿

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CLETOCAMPTUS RETROGRESSUS (COPEPODA, HARPACTICOIDA) FROM IRRIGATION AND DRAINAGE DITCHES OF THE RHÔNE DELTA (CAMARGUE, FRANCE) A REDESCRIPTION

W. MIELKE Institut fiir Zoologie und Anthropologie, Universitàt von Gôttingen, Berliner Str. 28, D-37073 Gôttingen, Germany

CLETOCAMPTUS RETROGRESSUS RÉSUMÉ. - Des exemplaires de Cletocamptus retrogressus Schmankewitsch, 1875 COPEPODA HARPACTICOIDA ont été collectionés en Camargue dans des canaux d'irrigation et de drainage (delta MORPHOLOGIE du Rhône) de salinité variable. Cette espèce, qui a été trouvée en plusieurs endroits CANAUX CAMARGUE d'Europe, en Afrique et en Asie, restait encore mal connue. Nous la décrivons à nouveau, et tenons compte notamment du dimorphisme sexuel du rostre et des piè- ces buccales qui sont souvent négligées.

CLETOCAMPTUS RETROGRESSUS ABSTRACT. - Spécimens of Cletocamptus retrogressus Schmankewitsch, 1875 COPEPODA HARPACTICOIDA were collected in the Rhône delta, Camargue, from irrigation and drainage ditches MORPHOLOGY containing water of fluctuating degrees of salinity. Thus far, the species, recorded DITCHES CAMARGUE from many European, African and Asian localities, has been presented only defi- ciently; in this paper it is redescribed and figured, including the sexualdimorphic rostrum and the mostly neglected mouth parts.

INTRODUCTION their morphology should be elaborated carefully. The présent animais have been collected from the Camargue and attributed to C. retrogressus, which has already been recorded from that région The genus Cletocamptus Schmankewitsch, 1875 (Aguesse & Dussart 1956). The species is now has a changeable history as to species number, ge- redescribed and illustrated in détail. nus synonymy and family affiliation. The diverse species have been classed with gênera like , , Godetella, Marshia, or Régis and ranked among the MATERIAL AND METHODS Cletodidae or the . Actually Cleto- camptus is integrated in the Canthocamptidae, however, as "incertae sedis" (Por 1986, adopted by The Cletocamptus spécimens were collected by Ku- Huys et al. 1996, Bodin 1997). According to nert (1991) in différent irrigation and drainage ditches of Fleeger (1980) the genus comprises 12 species. 3 the Rhône delta as co-inhabitants of the plathelminth new species have been recently added. Gee (1999) Macrostomum romanicum Mack-Fira, 1968, the real ob- described C. merbokensis from a mangrove habitat ject of her dissertation. The animais were caught by of the Peninsula Malaysia. Mielke (2000) recorded using a hand-net; occasionally the sédiment was whirled up beforehand. The concentrate in the hand-net was pou- 2 species, C. axi and C. schmidti, from the red in pétri dishes, the were sorted out under a Galapagos Archipelago. Some Cletocamptus spe- stereo microscope and then fixed in vials in a 4 % forma- cies (C. deitersi (Richard, 1897), C. confluens (Schmeil, lin solution. 3 ?î and 3 c? c? were dissected and embed- 1894) and C. retrogressus Schmankewitsch, 1875) ded in W 15 médium (Zeiss); the cover glass was sealed are known to be geographically widespread, mor- with Eukitt and DePeX. Drawings were made with the phologically "plastic" and ecologically variable aid of a caméra lucida. The interprétation of body, thus implying the existence of morphologically in- mouth parts and thoracopods is adopted from Lang distinguishable sibling species (Dexter 1995 for (1948; 1965). With respect to the mouth parts, the inter- C. deitersi) or even species conglomerations. prétation of the components according to Huys & Boxs- hall (1991) is given in parenthèses. The material has In order to achieve clarity on the systematic po- been deposited in the collections of the Zoological Mu- sition of the respective species at the very least séum of the University of Gôttingen. 2 MIELKE W

DESCRIPTION sisting of 2 segments, furnished with 1 and 2 setae, respectively.

Canthocamptidae incertae sedis Maxillula (Fig. 2D, E) with 7 slightly curved, Cletocamptus Schmankewitsch, 1875 claw-like appendages and 2 plumose spines on dis- Cletocamptus retrogressus Schmankewitsch, 1875 tal margin and 1 seta on surface of the praecoxal arthrite. Coxa has 2 setae. Basis, exopodite and Locality: Near to the Plage de Beauduc, endopodite fused; part of basis bears 3 setae api- Camargue, France. Irrigation and drainage ditches/ cally and 2-3 setae subapically; endopodite repre- channels of the Rhône delta (September 1986, leg. sented by 2 or 3 setae, exopodite by 1 seta. T. Kunert; see Kunert 1991); fréquent species. 3 9 ? and 3 6 Ô were dissected (reg. nos. I Fra 1-6). Maxilla (Fig. 2F). Syncoxa ornamented with several rows of spinules; 2 well developed endites distally, each one furnished with 3 éléments. Basis Female (allobasis) has 1 unipinnate claw and 1 seta. Endopodite seemingly weakly 1-segmented, carries Body length of three dissected females from tip 3 slender bare setae. of rostrum to end of furcal rami 0.84-0.94 mm. Distal part of rostrum spinulose, subdistally with a Maxilliped (Fig. 3B) 3-segmented. Basis slender setule on each side (Fig. 2A). Dorsal caudal (syncoxa) covered with several rows of spinules; 1 margins of céphalothorax and following 3 somites short seta arises on distal inner edge. Proximal furnished with weak spinules. Caudal margins of endopodite segment (basis) as well with several remaining somites as well as ventral caudal mar- rows of spinules on surface and on inner margin. gins of abdominal somites set with stronger spi- Distal endopodite segment (endopodite) with 1 nules. Surface of céphalothorax and subcaudal sur- slender claw and 1 seta, which inserts at the basai face of other somites - except of anal and part of the claw. penultimate somites - ornamented with fine PI (Fig. 3C). Coxa subdistally with a row of spi- setules. Anal somite with a pair of setules in the nules. Basis furnished with some rows of spinules, midst. Génital double-somite subdivided and a spine on inner and outer edge, respectively. dorsolaterally. Middle part of ventral surface of ab- Exopodite 3-segmented, ail segments of about the dominal somites with rows of spinules, laterally same length, inner and outer margins spinulose. (except anal somite) with irregularly arranged spi- Outer spines of basai and middle segments slender, nules. Distal margin of anal operculum spinulose. middle segment has 1 inner plumose seta. Distal Furcal rami about 2.5 times longer than broad. segment bears 2 slender outer spines, 1 bare and 1 Outer margin proximally with 1 very small seta, at plumose seta apically. Endopodite 2-segmented, about middle part 2 slender setae stand. Subdistally inner and outer margins of both segments set with on dorsal surface 1 seta inserts; it is bipartite at slender spinules. Basai segment with 1 plumose base. Distal margin has 3 setae: inner one naked seta arising subdistally on inner margin. Distal seg- and short, middle one bulbous on proximal part, ment slightly shorter, carries 1 plumose seta fused with slender outer seta; both setae plumose subapically and 2 setae apically. (Fig. 1A, B). P2-P4 (Fig. 3E, 4A, B). Praecoxae with a row of Antennula (Fig. 2A) 6-segmented. Armature of spinules subdistally on surface. Coxae ornamented segments: 1 (2 rows of spinules and 1 seta), 2 (9 with rows of spinules on surface and near outer setae), 3 (6 setae), 4 (2 setae and 1 aesthetasc), 5 (1 margin. Bases with spinules at outer lobe and near seta), 6 (10 setae and 1 aesthetasc). the insertion point of the endopodites. Outer lobe Antenna (Fig. 3A). Coxa short, furnished with 2 with a spine (P2) or a slender seta (P3 and P4). Dis- rows of spinules. Anterior margin of allobasis set tal middle edge of bases and distal inner margins of with slender spinules and obviously with 1 seta proximal endopodal segments of P2 and P3 with a only (probably 1 of the proximal spinules in reality tooth-like extension; in P4 thèse structures are represents another seta). Free endopodite segment rather weak. Exopodites 3-segmented; outer mar- apically with 1 row of spinules, laterally with some gins set with stout spinules, inner margins have slender and a few stout spinules; anterior margin slender, hair-like spinules. Proximal and middle with 2 spines of différent lengths and a small seta. segments each with an outer spine, middle seg- Apical armature represented by 2 slender spines of ments with 1 inner plumose seta. Distal segments différent lengths, 2 geniculate setae and 1 outer bi- bear 2 bipinnate outer spines, 2 apical plumose pinnate seta. Exopodite 1-segmented, slender, setae (except of inner one of P4), and 1 (P2 and P4) bears 3 setae and a few spinules. or 2 (P3) setae on inner margin. Endopodites 2-seg- Mandible (Fig. 2C). Corpus mandibulae orna- mented. Proximal segments short, distal inner edge mented with rows of slender spinules. Cutting edge produced into a tooth-like extension; inner and with several teeth; 1 unipinnate seta, which is obvi- outer margins set with slender spinules. Margins of ously fused to a curved, hyaline structure, inserts long distal segments as well spinulose, furnished laterally. Palpus seems to be slightly variable, con- with 4, 5, 2 plumose setae, respectively. CLETOCAMPTUS RETROGRESSUS FROM THE RHÔNE DELTA 3

Fig. 1. - Cletocamptus retrogressus. A, Habitus dorsal female; B, Abdomen ventral female; C, Abdomen ventral maie.

Seta and spine formula: Maie

Exopodite Endopodite Differs from the female in the following re- PI (0.1.022) (1.120) P2 (0.1.122) (0.121) spects: Body length of 3 dissected spécimens 0.72- P3 (0.1.222) (0.221) 0.77 mm. Spinulation of abdominal somites more P4 (0.1.122) (0.110) distinct (Fig. 1C). Length-width ratio of furcal rami somewhat greater. Proximal part of middle P5 (Fig. 5A). Baseoendopodite and exopodite terminal seta only slightly bulbous (Fig. 1C). Ros- fused. Inner part of benp. with 6 pinnate setae of trum more slender (Fig. 2B). Antennula différent lengths, outermost but one longest; por- subchirocer. Inner edge of basis PI tooth-like ex- tion of exp. with 5 setae, innermost but one lon- tended, inner seta slender (Fig. 3D). P2 weakly gest. modified. Basai segment of exopodite P3 (Fig. 5B) Fig. 2. - Cletocamptus retrogressus. A, Rostrum and antennula female; B, Rostrum maie; C, Mandible female; D, Maxillula female; E, Outer margin of fused basis, enp. and exp. of other maxillula female; F, Maxilla female. CLETOCAMPTUS RETROGRESSUS FROM THE RHÔNE DELTA 5

Fig. 3. - Cletocamptus retrogressus. A, Antenna female; B, Maxilliped female; C, PI female; D, Inner margin of basis PI maie; E, P2 female. 6 MIELKE W

Fig. 4. - Cletocamptus retrogressus, female. A, P3; B, P4.

enlarged; éléments of distal segment shorter, above sionally 3) setae. P6 ( ?) obviously represented by ail apical outer one; endopodite 3-segmented; inner very transparent plates (see Fig. 1C). edge of middle segment produced into a spine-like process; distal segment roundish, bears 2 plumose setae. Basai segment of exopodite P4 (Fig. 5C) ro- DISCUSSION bust, enlarged; éléments of distal segment shorter, above ail apical outer one; endopodite corresponds to the one of female, but both setae of distal seg- A multitude of records exists for ment distinctly shorter. Baseoendopodite and C. retrogressus, often solely in species lists, some- exopodite P5 (Fig. 5D) fused; inner part of benp. times completed by ecological or morphological with 3 (occasionally 4), part of exp. with 4 (occa- data. Other than the contributions mentioned in CLETOCAMPTUS RETROGRESSUS FROM THE RHÔNE DELTA 7

Fig. 5. - Cletocamptus retrogressus. A, P5 female; B, P3 maie; C, P4 maie; D, P5 maie.

Lang (1948) several authors give additional figures Damian-Georgescu figure the palp of the mandible, of the antennula, the antenna, the furcal rami and/ being 2-segmented and furnished with 3 setae. This or the peraeopods, e.g. Chappuis 1944, Stephanides state corresponds to the one of the présent animais. 1948, Borutzky 1952, Kiefer 1952, Margalef 1953, The rudimentary seta at the proximal outer margin Aguesse & Dussart 1956, Dussart 1967 (figures of furcal rami is generally overlooked. Further- adopted by Janetzky et al. 1996), Damian- more, the différent shape of rostrum ? and S is not Georgescu 1970, Apostolov 1973, Dumont & emphasized anywhere. However, Sars (1903) illus- Decraemer 1977, Tai & Song 1979, Apostolov & trâtes female and maie spécimens from the dorsal Marinov 1988. In thèse contributions the mouth side whereby the différence can be seen. parts are usually neglected. Borutzky as well as 8 MIELKE W

A décisive question is whether or not the species and résistance to extrême living conditions. Sites ranked with Cletocamptus actually represent a are known in North Africa, South, Central and East monophyletic taxon. Chappuis (1933, p. 397) de- Europe as far as the Central Asiatic région. notes as being typical for the genus: (a) common The species has already been found in the shape of the furca, (b) structure of P5, (c) sparse Camargue/France, reported for the first time by setation of exp. P4, (d) form of enp. P3 S, (e) Aguesse & Dussart (1956). Concerning the occur- structure of female génital area. Above ail, the fu- rence Aguesse ("Remarques écologiques", p. 506) sion of benp. and exp. P5 ? and S must be stressed points out that C. retrogressus "se trouve jusque (convergent or synapomorphic with ?). dans les bassins de concentration des salines, vi- Because of the unsatisfactory knowledge of the vant avec les Artemia salina". Kunert (1991, p. 3) mouth parts possible autapomorphies, e.g. the palp characterizes the locality as follows (translated or the hyaline appendage at the chewing edge of from German): "There are high degrees of salinity the mandible, cannot be evaluated. A common, (70-200 %o) and fluctuations of salinity in the irri- possible apomorphic feature of Cletocamptus could gation and drainage ditches due to the transitory also be the tooth-like extension of the inner margin drying up as a resuit of the high rates of evapora- and the lengthened inner seta of the basis PI â tion at the high intensity of insolation during the compared to the female. Obviously, in most de- summer months and the merely sporadic influx of scriptions this character was ignored. On the other slightly saline freshwater from the Rhône. The hand, this transformation could be demonstrated fluctuations of the température, caused by sudden for C. affinis Kiefer, 1957; C. albuquerquensis influx of freshwater are likewise considérable". (Herrick, 1895), (compare Pallares 1962); C. bicolor (Wilson, 1932), (according to Yeatman ACKNOWLEDGEMENT. - I am grateful to Dr. T Kunert (1963) identical with C. deitersi; Wilson (1932) for placing the material at my disposai. only figured the inner process but not the accompa- nying seta); C. retrogressus Schmankewitsch, 1875. Furthermore, two new recently described REFERENCES Cletocamptus species from the Galapagos Archi- pelago, C. axi and C. schmidti (Mielke 2000), both closely related to C. deitersi (Richard, 1897), Aguesse PC, Dussart BH 1956. Sur quelques crustacés clearly exhibit this characteristic feature. However, de Camargue et leur écologie. Vie Milieu 7: 481-520. in C. merbokensis, recently recorded from the Pen- Apostolov A 1973. Harpacticoïdes des eaux saumaitres insula Malaysia, such a dimorphic structure ap- et des étangs côtières. Zool. Anz. 191: 281-294. pears to be lacking (Gee 1999). For the other spe- Apostolov AM, Marinov TM 1988. Copepoda, Harpacti- cies its (non-) existence must still be checked. The coida. In Fauna Bulgarica 18, Aedibus Acad Sci Bulg situation of C. confluens (Schmeil, 1894) is some- 384 p. what différent. In this case, only a long and slender Bodin P 1997. Catalogue of the new marine Harpacti- seta is présent in the maie but the inner margin of coid Copepods (1997 Edition). Doc trav Inst roy Sci nat Belg 89: 1-304. the basis has the normal shape (primary or Borutzky EV 1952. Freshwater Harpacticoida. In Fauna secundary condition ?, see Mielke 2000a). of U.S.S.R. Crustacea III (4). 424 p. In ail probability the genus Cletocamptus repre- Chappuis PA 1933. Sul3— und Brackwasser Copepoden sents a paraphyletic assemblage of partly cosmo- von Bonaire, Curaçao und Aruba. I. Harpacticoida. politan or distinct but morphologically similar spe- Zool Jb Abt Syst Ôkol Geogr Tiere 64: 391-404. cies. Gee (1999) interprets Cletocamptus to be "an Chappuis PA 1944. Die harpacticoiden Copepoden der amalgam of a number of gênera". A revision of that europâischen Binnengewâsser. Arch Naturgesch NF species complex of unsure systematic relationship 12: 351-433. is highly désirable, however, the présent state of Damian-Georgescu A 1970. Copepoda Harpacticoida information (mouth parts, sexual dimorphism) for (forme de apa dulce). In Fauna Republicii Socialiste some species is déficient and prevents any serious Romania. Crustacea IV (11), 248 p. attempt. Dexter DM 1995. Salinity tolérance of Cletocamptus deitersi (Richard 1897) and its présence in the Salton Sea. Bull South Calif Acad Sci 94: 169-171. Dumont HJ, Decraemer W 1977. On the continental co- ECOLOGICAL NOTES pepod fauna of Morocco. Hydrobiologia 52: 257-278. Dussart BH 1967. Les Copépodes des eaux continentales d'Europe occidentale. I: Calanoïdes et Harpacticoï- des. E N Boubée & Cie, 500 p. Cletocamptus retrogressus is a widely distrib- Fleeger JW 1980. Morphological variation in Cleto- uted species inhabiting inland waters of very dif- camptus (Copepoda: Harpacticoida), with description férent salinity concentrations such as lakes, la- of a new species from Louisiana sait marshes. Trans goons, ponds, ditches - occasionally existing Amer Micros Soc 99: 25-31. merely temporarily. Locally the species occurs in Gee JM 1999. A new species of Cletocamptus Schman- huge quantities demonstrating its great tolérance kewitsch, 1875 (Copepoda; Harpacticoida) from a CLETOCAMPTUS RETROGRESSUS FROM THE RHÔNE DELTA 9

mangrove forest in Malaysia. Hvdrobiologia 412: ted to the cosmopolitan C. deitersi. J Crust Biol 20: 143-153. 273-284. Huys R, Boxshall GA 1991. évolution. Ray Mielke W 2000a. A new record of Cletocamptus con- Soc London, 468 p. fluens (Schmeil, 1894) (Copepoda Harpacticoida) Huys R, Gee JM, Moore CG, Hamond R 1996. Marine from a small pond in north-west Namibia. Trop Zool and brackish water harpacticoid copepods. Part t. Sy- 13: 129-140. nopses of the British Fauna (N.S.), FSC Publ, Preston Pallares RE 1962. Nota sobre Cletocamptus albuquer- Montford, Montford Bridge, Shrewsbury, U.K. 352 p. quensis (Herrick), 1895 (Crust. Copepoda). Physis Janetzky W, Enderle R, Noodt W 1996. Crustacea: Co- 23: 241-244. pepoda: Gelyelloida und Harpacticoida. In SuBwas- Por FD 1986. A re-evaluation of the family Cletodidae serfauna von Mitteleuropa, 8 Schwoerbel J & Zwick Sars, Lang (Copepoda, Harpacticoida). Proc Sec Int P eds, Gustav Fischer Verlag, 227 p. Conf Copepoda. Syllogeus 58: 420-425. Kiefer F 1952. Beitrag zur Kenntnis der Copepodenfau- Sars GO 1903. On the Fauna of Central Asia. na Algériens. Bull Soc Hist Nat Afr Nord 43: 87-112. Part III. Copepoda and Ostracoda. Ann Mus zool Acad Kunert T 1991. Zur Ultrastruktur und Embryonalentwic- imp sci St Pétersbourg 8: 195-232. klung von Macrostomum romanicum Mack-Fira, Stephanides T 1948. A survey of the freshwater biology 1968 (Macrostomida, Plathelminthes). Diss Univ of Corfu and of certain other régions of Greece. Prakt Gôttingen, 181 p. Hell hydr Inst 2, 263 p. Lang K 1948. Monographie der Harpacticiden, I & II: Tai AY, Song YZ 1979. Fauna Sinica, Crustacea, Fresh- 1682 p. (Reprint 1975, Otto Koeltz Sci Publ, Kônigs- water Copepoda. Science Press, Peking, 450 p. tein). Wilson CB 1932. The copepods of the Woods Hole ré- Lang K 1965. Copepoda Harpacticoidea from the Cali- gion Massachusetts. Smiths Inst US Nat Mus 158: 1- fornian Pacific coast. Kungl Svenska Vetenskaps 635. Handl 10: 1-566. Yeatman HC 1963. Some redescriptions and new records Margalef R 1953. Los crustâceos de las aguas continen- of littoral copepods for the Woods Hole, Massachu- tales ibericas. Biologia de las aguas continentales setts région. Trans Amer Microsc Soc 82: 197-209. X. Inst forestal invest exp, Madrid, 243 p. Mielke W 2000. Two new species of Cletocamptus (Co- Reçu le 19 février 2000; received February 19, 2000 pepoda: Harpacticoida) from Galapagos, closely rela- Accepté le 4 août 2000 ; accepted August 4, 2000 10 ANALYSE D'OUVRAGE/BOOK REVIEW

ANALYSE D'OUVRAGE/BOOK REVIEW

H. KEUPP, 2000. Ammoniten - Palàobiologische loge initiale de la coquille chez les Ammonites et la Spi- Erfolgsspiralen. Jan Thorbecke Verlag (E-mail : rule. Cette ressemblance peut être interprétée comme un [email protected]), Senefelderstrasse 12, Postfach caractère synapomorphe, en dépit du sens opposé de 4201, D-73745 Ostfildern Allemagne). 165 p., 283 l'enroulement de la coquille (exogastrique chez les fig., 24 x 28 cm. Couverture : carton rigide et simili Ammonites, endogastrique chez la Spirule). En re- tissu. 30.17 Euros. vanche, la correspondance entre le sens de l'enroulement des coquilles de Nautiles et d'Ammonites est probable- Pour ce qui est des Céphalopodes en général, le Nau- ment une « analogie » (ou convergeance). tile, seul rescapé vivant d'un groupe très ancien, repré- A partir des arguments fournis par une analyse com- sente un modèle de recherche apprécié par les parée des structures et des comportements observés chez paléontologistes et les néontologistes. Par contre, peu de les Céphalopodes vivants, Keupp retient trois hypothè- biologistes semblent s'intéresser aux Ammonites, étein- ses pour une reconstitution bio-morphologique des tes depuis 65 millions d'années, donc inaccessibles à Ammonites : (1) impossibilité, pour l' doté d'une une recherche biologique. Ce fait est indéniable ; il reste coquille externe, de s'alimenter comme un chasseur ac- que les Ammonites étaient très probablement parmi les tif; (2) présence d'un mode reproducteur (marqué par plus proches parents des Coléoidés (Céphalopodes à co- une sélection « relativement r ») ainsi que d'appareils quille interne ou absente), aujourd'hui représentés par branchiaux et brachiaux de type « moderne » (2 bran- les Céphalopodes vivants autres que le Nautile. Cette hy- chies, max. 10 bras); (3) persistence de caractères plé- pothèse de proche parenté émise par des paléontologis- siomorphes : il de type « chambre obscure », bras tes, est importante pour les biologistes qui essaient de dépourvus de structures préhensiles spécialisées, ab- comprendre l'évolution des Céphalopodes, et en particu- sence d'une poche d'encre. lier pour ceux qui s'intéressent aux transformations pas- sées du complexe coquillier. Un bref rappel traite de la nomenclature et de la taxo- Voici un livre, rédigé par un paléontologiste, qui fait nomie des Ammonites, en jetant les bases pour le grand le point des connaissances acquises sur les Ammonites, chapitre sur la morphologie fonctionnelle et la structure présentées dans une optique biologique. Le sous-titre du des coquilles, leur ontogénie, les caractéristiques des li- livre (spirales d'un succès paléobiologique) souligne gnes lobulaires (et leur utilité pour la recherche phylogé- cette perspective qui enrichit les recherches menées en nétique), le dimorphisme sexuel, le nanisme et le paléontologie depuis un siècle. Comme le souligne H.- gigantisme, les convergences morphologiques, puis les G. Herbig, dans sa préface, les Ammonites allaient de caractères internes liés à l'ancrage des muscles dans la succès en succès pendant 350 millions d'années : après coquille, la masse buccale avec les mandibules (dont chacune des grandes crises qui avaient balayé la plupart l'inférieure forme un bouclier nomméaptychus) et la ra- des formes, les quelques survivants avaient les moyens dula, les contenus stomacaux et les néphrolithes. de s'adapter aux conditions changeantes des milieux ma- Les interactions synécologiques entre Ammonites et rins - jusqu'à la fin du Crétacé. autres organismes (prédation, époecie, parasitisme) sont Avant de s'attaquer aux grandes questions de paléo- abordées avant la synthèse finale sur la phylogenèse des biologie, Keupp rappelle la longue tradition de « l'am- Ammonites et les 350 millions d'années de leur « car- monitologie » ; il rend hommage à U. Lehmann rière réussie ». (université de Hambourg) qui avait rendu ce domaine ac- Une brève description des conditions ayant permis cessible au grand public. Le point de départ de sa propre une fossilisation est suivie d'un rappel historique sur le analyse est la différence morphologique entre la coquille rôle des Ammonites dans les croyances populaires. du Nautile et celle des Ammonites, qui soulève le pro- L'ouvrage se termine par un excellent glossaire et une blème des limites d'une comparaison entre le « fossile bibliographie comprenant plus de 500 références. vivant » qu'est le Nautile et la multitude de « fossiles Ce qui rend ce livre particulièrement attractif, même morts » que représentent les Ammonites. Cet aspect est pour ceux qui éprouvent quelques difficultés à lire approfondi dans un chapitre consacré à la position systé- l'Allemand, est la tès belle qualité de l'ensemble des il- matique des Céphalopodes vis-à vis des autres Mollus- lustrations -qualité technique, didactique, esthétique. Le ques, et à celle des Ammonites au sein de la classe des grand format du livre a permis de reproduire des macro- Céphalopodes. Un cladogramme synthétique résume les photos (la plupart en couleur) et des clichés de micros- connaissances actuelles, en insistant sur l'éloignement copie photonique et électronique sans aucune perte de du Nautile par rapport aux Neocephalopoda qui com- détail. Ce livre sera apprécié par la communauté scienti- prennent les Bactrites, les Ammonites, puis les Bélemni- fique (Sciences de la terre et Sciences du vivant confon- tes (disparues à la même époque que les Ammonites) et dues), et il fera date dans la littérature consacrée à une d'autres Coléoidés (Spirule, Seiches, Calmars, Vampy- « vulgarisation de haut niveau ». romorphes et Octopodes). Keupp insiste en particulier sur la ressemblance morphologique et structurale de la S. v. Boletzky