ANN ALES • Ser. hist. nat. • 13 ■ 2003 • t
review	UDK 591.9:574,5(262.3-18)
received: 2003-03-10
MEiOBENTHIC FAUNA (WITHOUT HARPACTICOIDA) IN THE SOUTHERN PART OF GULF OF TRIESTE.. SLOVENIA: LIST OF TAXA
Borut VRISI-R
National Institute of Rioiogy, Marine Biology Station. SI-6330 Piran, Fornai.fi 41 F-mail: vfiser@mbss.ocg
ABSTRACT
The article presents an integral systematic review of meiobenihic latina (without tiie already presented Copepoda Harpactico'tda), arranged on the basis of extensive material gathered in the course of numerous investigations during the last 30 years in the southern part of the Gulf of Trieste. The emphasis is on a systematic survey, which includes a ■otal of 30 higher taxa with nearly 180 species, although still a minor part of all expected but undiscovered species of the area.
Key words: meiofauna, list of taxa. Gulf of Trieste, Slovenia
FAUNA MEIOBENTONICA (ESCLUSI GLI ARPACTICOIDI) DELLA PARTE MERIDIONALE DEL GOLFO DI TRIESTE, SLOVENIA: LISTA DEI TAXA
SINTESI
L'aiticolo presenta una revisione sistemática integrate deila fauna meiobentonica (esclusi i copepodi arpacticoidi gia presen ta ti), preparata in base al vasto moteriale raccolto durante le numeróse ricerche effettuate negh ultimi 30 anni nella parte méridionale del Golfo di Trieste. Posta in rilievo Tindagine sistemática che include 30 tasa superiori con quasi 180 specie, benché queste rappresentino solo Lina piccola parle di lutte le specie atiese ma ancora sconosciute dell'area.
Parole chiave: meiofauna, lista dei taxa. Golfo di Trieste.. Slovenia
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INTRODUCTION
The paper presents meiofauna of the southern part of Gulf of Trieste, Copepoda excluded. The present work is a continuation of the survey of nieiobenthos in the Slovene sea (initiated several years ago), with an emphasis on its species structure and spatial distribution. In the first two articles (Vriser, 2000a, b), the systematic« and ecology of harpacticoid copepods (Copepoda, Harpac-ticoida) as one of the most dominant groups were presented, while the aim of this paper is to outline the taxonomic structure of the remaining meiofauna.
Meiobenthos of the southern part of Gulf of Trieste has so far not been researched at: such level as already mentioned harpacticoid copepods. The extent of more complete taxonomic determinations is here incomparably poorer. Amongst the causes for such state of affairs we must highlight, apart from a truly exceptional bulk of the material itself, mainly the following very specific and excusable reasons:
1.	in many groups, particularly in those that are sparse or with more delicate body structure, taxonomic study would require some very special and to them adapted sampling techniques and substantially greater number of parallel samples, as well as often repeated seasonal sampling;
2.	even today, many groups remain poorly researched, with insufficient, outdated or hardly accessible literature;
3.	lack of suitable specialists or taxonomic consultants;
4.	predominantly juvenile character of several groups (temporary meiofauna, i.e. juvenile stages of the future macrofauna), which greatly aggravates precise identification of species;
5.	damaged body structures of the more delicate, especially "worm-J ike* groups owing to the use of routine methods of fauna extraction from the substrate, which are more or less unsuitable for these particular groups;
6.	incompatibility of the necessary (stated) specific methodological approaches with simultaneous demands of general ecological stLidies of the great spalial or temporal frequency span.
In spile of it all, a fairly clear structural and ecological picture has crystallised from the research lasting for more than thirty years, which in many groups reached a notable degree of a systematic, rounding up. The research into some methodologically exceptionally demanding taxa unfortunately remained at its initial stage (e.g. Nemertinea, Nematoda, Oligochaeta, if mentioning only the most abundant ones) and is still waiting to be continued.
We believe that in spite of the above-mentioned gaps, fauna other than copepod, too, would deserve its first presentation of a clearer although for the time being still unavoidably preliminary systematic survey.
MATERIAL AND METHODS
Most of our samplings were implemented with gtav-tty core sampler (Meischner & Rumohr, 1974); only in lagoonar conditions they were also carried out manually, always with three parallel samples in the surface sediment of 10 cm2, 5-10 cm deep. Meiofauna was extracted with the sieving-dec.antation technique according to Wieser (I960) on 1 mm, 0.125 mm, and 0.050 mm sieves, preserved (4% formalin with seawater), sorted out, counted and, if at ail possible, identified to its species.
Only a minor part of the meiofauna groups was taxonomicafly analysed by specialists: Foraminifera (Franc Cimerman, Slovenian Museum of Natural History, Ljubljana), Polychaeta (Andrej Avčin, Marine Biology Station Piran, National institute of Biology, Ljubljana), Tanaidacea (Dušan Zavodnik, Centre for Marine Research, Rudjer Boškovič Institute, Rovinj), Insecta (Ignac Sivec, Slovenian Museum of Natural History, Ljubljana), Bryozoa (Brian M. Marcotte, Clark University, Worcester, USA).
For taxonomic: determination, authentication and classification of all remaining groups stated in brackets below, the author used the following important references:
Barlsch &■ 11 ifte, 1985 (Acarina); Bonaduce ei a/., 197S (Ostracoda); Bouillon & Grohmailn, 1990 (Hydro-zoa); Chevreux & Fage, 1925 (Amphipoda); De Min & Vio, 1997 (Gastropoda, Bivalvia); .Gruner, 1965 (Iso-poda), Hlggins, 1977 (Kinorhyncha); Hulings, 1971 (Hydrozoa, Kinorhyncha); Kara man, 1972, 1973, (Amphipoda); Klie, 1938 (Ostracoda); Nordsieck, 1968, 1972 (Gastropoda), 1969 (Bivalvia); Piatt & Warwick, 1983, 1988 (Nematoda); Riedl, 1956 ¡Turbeiiarta), 1983 (Anthozoa, Cirripedia, Decapoda, Curnacea, Lep-tostraca, Sipunculida, Chaetognatha, Holothurioidea, Asteroidea, Ophiuroidea, Echinoidea, Ascidiacea, Nemertinea); Rieger, 1971 (Turbeilaria); Salvinl-Plawen, 1966 (Hydrozoa); Sars, 1896 (Isopoda).
ECOLOGICAL CHARACTERISTICS OF THE RESEARCHED ENVIRONMENT
The so far carried out research into the meiofauna of southern Gulf of Trieste has dealt with the entire depth span of these waters: from 0.3-5 m in coastal studies, to the samplings in the Gulf's open waters (19-30 in depth). Meiofauna of the four coastal sampling profiles (1-15 m) in the Bays of Koper, Strunjan and Piran was comparatively researched In the summer and winter months, while the meiofauna of deeper areas was studied only in the SLimmer.
Thermic conditions of the entire area range from 921 *C, with average salinity of 37.5 psu, oxygen content in the span of 55-96% saturation, except in the very rare
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periods of hypoxia crisis, when the values < an fall below 40%.
With the exception of some marginal coastal localities (Koper and Piran Bays), which were at the time of sampling still under a great impact of organic pollution of urban origin, all the remaining meiofauna dealt with in tins paper belonged to a clean and unburdened environment.
The substrate of the investigated area consists of clayey silt (10-20% clay), which along the coast gradually turns into silty clays (up to 25% of clay) and, towards the open sea, into fine sands (Ogorelec ei a/., 1991).
TAXONOMIC EXTENT OF RESEARCH INTO THE
MEIOFAUNA OF SOUTHERN GULF OF TRIESTE
laxonomic structure of meiofauna of the selected research area has in fact never been studied purposely (with the exception of harpacticoid copepods), at least not exclusively with this aim, for the emphasis was largely on the ecological complexities and typology of its associations. Although subordinate, it still was a component part of these investigations, whose selection, arranged according to the thematic criterion, is here presented only in a condensed form.
In Slovenia, the first ecological meiobentbic research was initiated by Marcotte & Coull (1974) on the coastal profile of Piran Bay. This research was followed by the author's investigations in the experimental basins of Strunjan (Vnser, 1979, 1982), on the coastal profiles of (he Bays of Koper, Strunjan and piran (Vnser, 1983-84. 1986), in the open waters of Gulf o; Trieste (Vriser, 1989, 1991, 1992), in the Bays of Strunjan and Izoia (Vriser, 1999, 2001), and in coastal lagoons (Vriser, 2002).
At first, i.e. until the mid-1980s, the investigations were still directed at utterly ecological objectives, dealing primarily with the impacts of pollution on the meiofauna's associations. Nonetheless, these works contributed most of the taxonomlc data presented herewith. To a smaller extent they were supplemented by the long-term studies of seasonal dynamics and meiofauna's long-term oscillations in the centre of Gulf of Trieste (Vriser, 1996, 1997; Vriser & VukoviC, 1999). as we I as of its recolonisation characteristics (Vriier, 1998; Vriser & Vukovic, 2000).
There are unfortunately no other studies that would have contributed to a clearer picture of the systematic structure of the meiofauna in the southern part of Gulf of Trieste, but let us mention numerous investigations of separate groups of this fauna on at least three sites in the immediate vk inity of our waters, which are due to their closeness ot a considerable significance for as well.
The first such site is situated close to Trieste (Italy): it is in fact the site of the former marine biology station,
where the first rneiobenthic determinations were made in the early 20°' century e.g. Griinspan (1908) with the group Gastrotricha.
The second such site is the area around Rovinj (Croatia), where numerous investigations were made in the 1950s and 1960s by a number of taxonomists, such as Riedi (1956) (group Turbeliaria), Sterrer (1965, 1967) (group Gnathostomuiicla), Schrom (1966a) (group Gastrotricha) and Salvini-Plawen (1966, 1968) (groups Cni-daria, Kaniptozoa. Aculifera).
The third interesting site is the area around Venice, where much research was carried out by Schrom (1966b, c), Hummon eJ a!. (1990) and Evans et at. (1993), all concentrating on (he group Gastrotricha, and by Rieger (1971) (group Turbellaria).
Here follows a survey of all 31 registered higher taxa of the researched meiofauna, arranged in systematic succession (Riedl, 1983). Only some of the groups and species from the list are planktonic, all the rest being benthic.
l or each group, an approximate estimate of their occurrence in our sea is stated, i.e. their quantitative representativeness (% relative abundance within total meiofauna, hereinafter referred to as rel. ab.) and an estimate of their systematic covering, i.e. of (lie suppositional and actually established number of species in the area researched. All estimates about the probable number of species stated in further text thus refer exclusively to meiofauna. For within the same groups the number of macrobenthic species can be here and there not only higher but also lower than in the meiofauna, i.e. by spatially variable share (number of species) of that particular meiofauna's component, which in contrast to the juvenile macrofauna does not surpass, not even in the adult stage, the size of 1mm (permanent meiofauna). However, the precise number of these species in the majority of dominant groups of our meiofauna is still not known.
FORAMINIFERA
Foraminifera, which are no doubt part of meiofauna, are by most meiofaunists omitted from their research for methodological reasons. Namely, with the standard methods of colouring, suitable for the remaining fauna, it is not possible to distinguish between live and dead foraminiferous individuals. Foraminifera can thus be subject of only specialised sampling techniques, extraction, colouring, separation and particularly identification.
Occurrence: massive. If taken into account, foraminifera would be one of the first three dominant groups of meiofauna. Number of species: no actual data at hand. All 13 determined species from our fist are from the Strunjan lagoon.
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ANNALES • Ser. hist. nat. ■ 13 • 2003 • 1
Rnrm VRiSER: MFIOBENTHIC FAUNA {WIIHOUÎ HARPACTTCOOA) IN THE SOUTH*RN PART Of CUF Ol- TRlLSTF, SLOVFNIA IISÏ OF TAXA. iJ.42
HYDROZOA
Occurrence: rare, more common only here and there, generally below 0.1% rel. ab. Number of species: unknown, perhaps up to 10 species. 5 species determined partially.
ANTHOZOA
Occurrence; only a few fragments of juvenile individuals were registered, presumably from the group of Anlhipatharia. Number of species: unknown.
TURBELLARIA
Occurrence: mass group in most samples. 1% rel. ab. Number of species: presumably up to 50, almost all of them permanently meiobenthic. 7 species determined partially.
NEMERTINEA
Occurrence: rare, below 0.2% rel. ab. Number of species: unknown, no determinations.
NFMATODA
Occurrence: most abundant, dominant group (70% rel. ab.l throughout in all samples! Number of species: unknown, possibly up to 100, almost exclusively permanent meiobenthic species. Only 4 less common species determined.
KINORHYNCHA
Occurrence: common group, 0.25% rel. ab. Number of species: about 10 species of permanent meio-tauna, 8 partial determinations.
POLYCHAtTA
Occurrence: third most abundant group (8% rel. ab.). Number of species: unknown, perhaps up to 100 species, to a great extent of temporary character (juvenile rnacrofauna), 38 species registered and in most cases determined.
OIJGOCHAETA
Occurrence: very abundant group (2% rel. ab.). Number of species: unknown, perhaps few dozen species. No species determined.
OSTRACODA
Occurrence: common group, mostly with low abun-
dances (0.25% rel. ab.). Number of species: unknown, perhaps over 50 species. 16 species registered and partially determined in our samples.
CIRRIPEDIA
Only two coinddentally caught juvenile individuals,
QECAPODA
Occurrence: rare, generally below 0.1% rel. ab. Number of species: perhaps up to 20 species, 10 more common species partially identified.
AMPHIPODA
Occurrence: modest, in places somewhat more common, generally below 0.1% rel. ab. Number of species: perhaps up to 30 species, 14 more common species partially identified.
ISOPODA
Occurrence: rare individuals, generally below 0,1% rel. ab. Number of species: unknown, 13 species partially determined.
MY5IDACEA
Occurrence: rare, mostly occurring individually, altogether below 0.1% rel. ab. Number of species: unknown, 4 species partially identified.
CUMACEA
Occurrence: rare, mostly occurring individually, altogether below 0.1% rel. ab. Number of species: perhaps above 10 species, 4 only partially determined.
TANAIDACEA
Occurrence: rare, mostly occurring individually, generally below 0.1% rel. ab. Number of species: 4, with 3 of them identified.
LEPTOSTRACA
A single identified individual.
ACARiNA
Occurrence: rare, mostly occurring individually, generally below 0.1% rel. ab. Number of species: perhaps up to 10 species, with 4 of them identified only partially.
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INSECTA
Some rare and in only at two localities found dipteral larvae (family Chironomidae) of unknown number of spei ies.
SIPUNCUUDA
A single and only partially determined individual.
GASTROPODA
Occurrence: common, although not massive, lisu-ally with a few individuals per sample. Altogether 0.30% rel. ab. Number of specics: unknown, possibly over 100 species. Only 10 species partially identified.
8IVALVIA
Occurrence: massive, even with a few dozen individuals per sample. Altogether 0.25% rel. ab. Number of species: unknown, possibly over 100 species, with only 9 partially determined.
BRYOZOA
Some rare inoividuals, 1 partially identified species.
CHAETOGNATHA
Two coincidentally caught planktonic individuals of the same species.
HOLOTHURIOIDEA
Some rare juvenile individuals, 3 partially identified species.
ASTEROIDEA
Some rare juvenile individuals, 1 identified species.
OPHIUROIDEA
Occurrence: all over the research area. Individual juveniles, only 1 species determined.
ECHINOIDEA
Some rare individual larvae of unknown number of species.
ASCIDIACFA
At the end of taxonomic survey of our meiofauna, a question might be raised, where to place, in view of its species diversity, the area researched, if looking at potentially similar parts of the near and far neighbourhood. No comparable surveys can unfortunately be traced, while any serious diversity evaluation of our data is rendered very difficult by at this moment still highly inadequate systematic extent of research into the dominant, abundant and species-rich groups, such as Nematoda, Oligochaeta, Nemertinea, Polychaeta, Gastropoda and Bivalvia. Much work is thus still waiting for the future laxonomists, for the species determinations carried so far have probably reached less than a third of their presumed total number.
In spite of the stated taxonomic gaps, we could venture a judgment - on the very basis of the existing facts - that along with harpacticoid copepods (130 species) the fauna presented in this paper (180 species) also significantly contributes to the high diversity of our coastal waters,
LIST OF SPECIES
With the exception of harpacticoid copepods, the iist presents all till now registered taxonomic groups of meiofauna in the area researched. They are arranged according to the already mentioned system, i.e. in compliance with the available degree of their systematic analysis. This, however, can be only at the level of the higher taxa (e.g. ordo, classis, subclassis, familial, or it is determined down to the level of genus and species. The different species within the same taxon are either indicated as undetermined number of species (spp.) or are differentiated and numbered (genus sp. 1, sp. 2, etc.). Complete species determinations were given where at all possible.
FORAMINIFERA
Ammonia beccarii (I...) - smooth Ammonia beccarii (I.) - ornamented Ammonia sp. 1 Cribroelphidium sp, 1 Eggerella advene Cushman Elphidium crispum (L) t'tphidium sp, 1 Milionelia sp. 1 Quinqueloculina sp. 1 Rosa I in a globularis d'Orbigny Sigmoilina cf. costata Schlumberger Trilocuiina laevigata d'Orbigny Trochammina intlata (Montagu)
HYDROZOA
Some rare larvae.	Siphonohydra sp. 1
Halammohydra sp, 1
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ANNALES • Ser. hist. nat. • 1.3 - 2003 • 1
Borat VKISER: MtlOBENÏHlC EAUNA (WITHOi IT HARPACT1COIDA)
Haiammohydra sp. 2 Pinushydra sp. 1 Psammohydra sp. 1
ANTHOZOA
Anthipatharia gen. spp.
TURBEI.l.ARIA
Allostoma sp. 1 Convoluta convoluta Abi Id Nemertoderma spp. Diopisthoporus spp. Mecynostomum spp. Paraphanostoma spp. Plagiostomum sp. 1
NEMERTINEA
Heieronemertini gen. spp. Hoplonemertini gen. spp.
NEMATODA
Cyatholaimus sp. 1 Desmosœlex sp, 1 Enoplus sp. 1
Euchromadora striata (Eberth)
KINORHYNCHA
Echinoderes sp. 1 Echinoderes sp. 2 Neocentrophyes sp. 1 Pycnophyes sp. 1 Pycnophyes sp. 2 Pycnophyes sp. 3 Trachydemus sp. 1 Trachydemus sp. 2
POI..YCHAETA
Aon ides oxycephala (Sars) Aricidca spp. Brada villosa (Rathke) Capiteila capitata (Fabricius) Capitellidae gen. spp. Cirratulus filiformis (Keferstein) Cossura soyeri l.aubier Dorvillea sp. 1
Eue I y me ne palermitana (Grube) Eunice vittata (delle Chiaje) Hesionidae gen. spp. Hyalinoecia brementi Fauve! Lumbrineris gracilis (Ehlers)
•V THF SOUTHERN PART OF G Lit F Of TRJESTE, SLOVENIA: LISTOF TAXA, îî-42
Lumbrineris spp. Magelona sp. 1 Maldane glebifex Grube Micronephtys sp. 1 Nereidae gen. sp. 1 Nereidae gen. sp. 2 Notomastus sp. 1 Notomastus sp. 2 Onuphis sp. 1
Owenia fu si formt s delle Chiaje Paraonis lyra Southern ProxiHella s p. 1 Proxillella sp. 2 Proxi Hella sp. 3 Prionospio cirrifera Wiren Prionospio maimgreni Claparede Sabellidae gen. spp. Scolelepis fuliginosa (Claparede) Sphaerosyllis sp, 1 Spionidae gen. spp, Spirorbinae gen, spp. Syllidae gen. sp. I Syllidae gen. sp. 2 Syllidae gen. sp. 3 Terebellides stroemi Sars
OLICOCHAETA
f rihytraeidae gen. spp.
OSÏRACODA
C.aHistocythere adriatica Masoli
Callisiocythere sp. 1
Callistocythere sp. 2
Costa ed ward s i (Roemer)
Costa batet (Orady)
C.ythere antiquata Baird
Cytherelta adriatica Ruggeri
Cytheridea neapolitana Kol mann
H Ht ermann icythere túrbida (G.W.Müller)
Loxoconhasp.1
Loxoconcha sp.2
Ncocytherideis sp. 1
Neocytherideis sp. 2
Pterygocythereis jonesi (Baird)
Semlcytherura sp. 1
Semicytheruta sp. 2
CIRRIPEDIA
Chthamalus sp. 1
DECAPODA
Callianassa stebbingi Borra
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Carcinus sp. 1	IANAIÜACEA
< rangori sp. 1	
/ riiusa masc.arone I lei bst	Apseudes iaireiüei (Mi Ine Edw.)
Galathea sp. 1	Leptochelia savignyi (Kroyer)
Hippolyte sp. 1	Tanais cavolinii Milne Edw.
Maciopodia longiroslris (Fabricius)	
Palaemon sp. 1	LEPTOSTRACA
Ptocessa canaliculata (Leach)	
Sicyonta sp. 1	Nebalia bipes Fabr.
amphipoda	ACARINA
Ampelisca typica (Bäte)	Agauopsis brevipalpus Trousseart
Ampelisca spinntpes Boeck	Agauopsis sp. 1
Ampelisca sp. i	C.opidognathus sp. 1
Ampelisca sp. 2	Copidognathus sp. 2
Caprella sp. 1	
Dexaminc sp. 1	INSECTA
Gammarus locusta (1..)	
Gammarus sp. 1	Chironomidae gen. spp.
Cammarus sp. 2	
Lepidepecreum sp. 1	S1PUNCULIDA
i ysianassa sp. 1	
L eucothoe sp. 1	Phascolosoma sp. 1
Phtisica manna Slabber	
Pseudoproteüa sp. 1	CASTROPODA
ISOPODA	Bittium reticulatum Da Costa
	Cerithium vulgatum Baiguiere
Aniloc ra physodes (L.)	Conus sp. 1
Arcturus sp. 1	Gibhula spp.
Bopyrus squillarum Latr.	Haminea hydalis (L.)
Ctrolana borcalis ltll.	Monodonta spp.
Cyathura carinata (Kr.)	Nassa spp.
Cymodoce truncata (Mont.)	Opistobranchia spp.
Dynamene sp.	Polyriices sp. 1
Gnathia sp. 1	Rissoa spp.
idotea baltica (pafl.)	
i.igia italica Fahr	BIVALVIA
Limnnna sp. 1	
Neiocilia sp. 1	Aloidis gibba (Olivi)
Syrt/suma sp. 1	Cardioidea spp.
	Chlamys sp. 1
mysidacea	Gastrana fragüis (L.)
	Loripes lacteus (L.)
Diamysis sp. 1	Macoma sp. 1
Mysi> sp. 1	Nucula sulcata (Bronn)
Siriella clausi C. Sars	Teilina pulchella Lamarck
Siriella sp. 1	Venerupis sp. 1
CLJMACEA	BRYOZOA
Cumelfa sp. 1	Aetidae gen. spp.
üiastylis sp. 1	ßioellardiidae gen. spp.
Iphinoe sp. 1	Monobryozoon gen. sp. 1
Leucon mediterraneus Sars	
39