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A Review of the Family Ceramonematidae (Marine Free CO Zoological Institute, St.Petersburg, 2002 A review of thefamily Ceramonematidae (marine free-living nematodes), withdescriptions of nine species fromthe White Sea A.V. Tches1Jnov & M.A. Miljutina Tchesunov, A.V. & Miljutina, M.A. 2002. A review of the family Ceramonematidae (ma­ rine free-living nematodes), with descriptions of nine species from the White Sea. ZoosystematicaRossica, 11(1): 3-39. Morphology, biology and taxonomy of the nematode family Ceramonematidae Cobb, 1933 are summarised and reviewed. Plesiomorph-apomorph polarities of cuticle sculp­ ture, cephalic sensilla pattern, amphid shape are revealed with use of the out-group com­ parison and ontogenetic observations. The genera Ceramonema and Pselionema arc dis­ tinguished by the most apomorph character states; both genera combined comprise the greatest number of species, of the widest overall ecological range. The other ceramonematid genera display more plesiomorph character states and contain much less species; these are strictly confined to coarse sands. Ceramonematidae are related to the families Diplopeltoididae sensu Tchesunov (I 990) and Tarvaiidae. The family Ceramonematidae consists of two subfamilies: Ceramonematinae with the genera Ceramonema (= Ceramo­ nemoides, = Cyttaronema), Dasynemel/a (= Leptodasynemella), Dasynemoides (= Dasynemelloides), Metadasynemella (= Dictyonemella), and Metadasynemoides, and Pselionematinae with the genera Pterygonema and Pselionema (= Pselionemoides). Modi­ fied diagnoses of the family, subfamilies and genera are given. Separation of higher ceramonematid taxa is based largely on features of body cuticle annulation as well as on anterior sensilla pattern, while cephalic ratio and finer details of body annulation are important forspecies discrimination. Annotated lists of species are given for each genus. The genus Ceramonema is subdivided into two subgenera, Ceramonema s. str. (body cuticular annules with zygapophyses) and Proceramonema subg. n. (body annules de­ void ofzygapophyses). New species fromthe White Sea (Ceramonemajluctuosumsp. n., C. marisalbi sp. n., C. mokievskii sp. n., Dasynemoides crassus sp. n., Metadasynemoides labiatus sp. n., Pselionema concinnum sp. n., and P mirabile sp. n.) are described. Dasynemella riemanni Haspeslagh is recorded for the first time fromthe White Sea. The description of Pselionema simplex De Coninck fromthe White Sea is supplemented with notes on juveniles. A. V. Tchesunov & M.A. Miljutina. Department of Invertebrate Zoology. Faculty ofBiol­ ogy, Moscow State University, Moscow 119899, Russia; e-mail: [email protected] INTRODUCTION Below we propose an essay on the family Ceramonematidae basing on some White Sea Members of the familyCeramonematidae have species here described. somewhat unusual or even oddly appearance among other marine nematodes. Their cuticle is HISTORY composed of broad and thick annules, which make together an impression of a strong sculp­ The first ceramonematid nematodes were de­ tured armour. Anteriorly, the cuticular annules scribed by Cobb (1920). He placed the central are fused together in a bullet-shaped cephalic genus Ceramonema Cobb, 1920 in a newly cre­ capsule. Because of the light-refractive cuticle, ated order Cytolaimia, which is not retained in the internalorgans of ceramonematids are hardly the modem nematode classification. Filipjev visible and, hence, poorly studied. The family ( 1922) is the only other author, who described a includes only marine species, mostly confined ceramonematid species in 1920's. Later, Cobb to coarse sands of sea shallows. The ceramone­ ( 1933) established the familyCeramonematidae. matids may be very conspicuous in some places Chitwood ( 1936) published brief descriptions of attaining even about 5-10% of the species com­ several further ceramonematid species. position. A peculiar featureof the ceramonematid Close and extensive study of ceramonematids biology is brood care. was undertaken by Belgian nematologists De 4 A. V. Tchesunov & MA. Miljutina: Ceramonematidae • ZOOSYST. ROS SICA Vol. 11 Coninck (1942) and Haspeslagh (1973, 1979). 1994 ). Cuticle as well as some details of cephalic De Coninck established a new standard of de­ end, pharynx and hindgut in Pselionema simplex tailed species descriptions and modifiedthe clas­ were studied by Tchesunov ( 1995). sification with amphid shape as a key character. Only two ceramonematid species were hith­ Haspeslagh understood the cuticle construction erto recorded from Russian seas: Pselionema at the optic level using some new terms ( e.g. annulatum from the Black Sea (Filipjev, 1922) zygapophyses) and performedan analysis of the and P. simplex from the White Sea (Tchesunov, family in terms of comparative morphology. 1995). Besides that, she complicated considerably the family classification by accommodating new MATERIAL AND METHODS characters (e.g. cuticle vacuolisation) and de­ scribed a number of minor new genera. How­ The specimens were collected either in the ever, her classification was not, on the whole, Kandalaksha Bay of the White Sea (Dasynemella accepted by some nematologists. riemanni andPselionema simplex)or in the Gorlo In l 950-l 960s, many new ceramonematid spe­ Strait of the White Sea (all the rest species). Sedi­ cies were described, especially by Gerlach (see ment sampling from the depths up to 30 m in the References) during his extensive exploration of Kandalaksha Bay was done by scuba divers, the the tropical and world faunas of marine nema­ samples in the Gorlo Strait as well as the sam­ todes. Contributions to knowledge of the diver­ ples from deeper sites in the Kandalaksha Bay sity of ceramonematid nematodes were made also were taken using a grab. Nematodes are mounted by Andrassy, Chitwood, Furstenberg & Vincx, in glycerine slides. Hopper, Platt, Timm, Vitiello, Ward, Warwick, The following abbreviations are used in the Wieser, and Zhang (see References). Platt & text: a: body length divided by maximum body Zhang (1982) published a pictorial key for spe­ diameter; a.b.d.: anal body diameter; b: body cies of Ceramonema. Hopper (1973) discovered length divided by oesophageal length; c: body the phenomenon of egg carrying by ceramo­ length divided by tail length; c.b.d.: correspond­ nematid females. ing body diameter; L: body length; V: distance Lorenzen (1981) anew reduced and thus sim­ of vulva from anterior end as a percentage of plified after Haspeslagh the classification of body length. Ceramonematidae reducing the number of gen­ era. The position of the family within the nema­ tode classification represents a particular prob­ MORPHOLOGY AND BIOLOGY lem. Long time, the ceramonematids were con­ sidered to be related to desmodorid or even Appearance monoposthiid nematodes and respectively were placed together or within those families. This idea Body of the ceramonematid nematodes is usu­ was fixed by inclusion of Ceramonematidae in ally cylindrical, short or thread-like, often wide the order Desmodorida by De Coninck (1965) anteriorly and slightly tapering toward the tail. and then by Gerlach & Riemann (1973). Loren­ More seldom, the body shape may be close to zen (1981) did not found any synapomorphies fusiform. Body length varies from 400 to shared by Ceramonematidae and desmodorid 3000 µm. A curious image of the worms is cre­ familiesand thereforeincluded the family Cera­ ated by the peculiar armoured cuticle. The cuti­ monematidae in the paraphyletic suborder Lepto­ cle consists of broad and thick annules connect­ laimina of the order Chromadorida. However ing by flexible membranes. Furthermore, the earlier, Gerlach ( 1950) already assumed forCera­ annules are sculpturally complicated by longi­ monematidae a tentative relation to diplopeltid tudinal ridges and thin undulating peaks over­ nematodes. Lorenzen (1981) considered Ceramo­ lapping the adjacent annules (Fig. 1). The peaks nematidae possibly to be related to Tubolaimo­ were termed by Haspeslagh (1973) as zygapo­ ididae basing on the similarity between Dasyne­ physes. They may enhance rigidity of the cuti­ me/la and Tubo/aimoides in the labial region, cle and diminish flexibilityof the body. Anterior­ buccal cavity, amphids, and shape and patternof ly, the cuticle formsa solid bullet-shaped cephalic the anterior setae. capsule. Posteriorly, the annules are fused into a In 1990s, first studies on ceramonematid ul­ solid terminal tail cone. Transverse sutures may trastructure appeared. Australian nematologists be retained anteriorly at the base of the terminal Nicholas and Stewart undertook TEM-investiga­ cone. Some ceramonematids provide numerous tions of cuticles in Metadasynemoides cristatus (up to seven hundred) cuticle annules equally and Ceramonema carinatum (Nicholas & Stew­ narrow throughout the body length. Other spe­ art, 1990; Stewart & Nicholas, 1992) and of an­ cies are characterised by smaller and rather sta­ terior body in C. carinatum (Stewart & Nicholas, ble (90-100) number of annules. In latter case, ZOOS YST. ROSSI CA Vol. 11 • A. V Tchesunov& MA. Miljutina: Ceramonematidae 5 field t····· ... epicrista --- 1 •• -•••-•••• • 1..... --• plane of articulation .c..... "O A ct:l i l lil � e .0 ridg @;1;; .. 11 ;;;;;;;;; ==t ·· =··;;;;;i===•······· •· .. zygapophysis B C Fig. I. Structure of ceramonematide cuticle. A, structural patternof an annule; 8, C, perspective sketches of the cuticle of Ceramonema carinatum. Abbreviations for B and C: BA, basal platform of cortical plate; CP, cortical plate; GR, groove between annules; OCP, overlapping projection; R, ridge;
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