Reproductive biology of several species of recently collected pelagic nemerteans

The reproductive biology and morphology of six polystiliferous and onemonostiliferous species of pelagic nemerteans was studied in specimensrecently collected off California. Depth distributions for these specimensranged from 250 m to 3250 m, with most specimens obtained between 700 m and1750 m. Length of sexually mature individuals ranged from 2 mm for themonostiliferan to 61 mm for a male Phallonemertes cf. murrayi. Among P. cf.murrayi and Nectonemertes cf. mirabilis, which yielded the largest specimensstudied, mature males were larger than mature females and mature animalswere larger than those in which gonads were not apparent. Females typicallyoutnumbered males, although N. cf. mirabilis approached a 1:1 sex ratio. Inthe polystiliferans studied by light microscopy, accessory ovarian cellsappeared to translocate yolk or yolk precursors to oocytes via cytoplasmicbridges, a mechanism typically associated with nurse cells and notpreviously reported from nemerteans. Mature oocytes 0.5–1 mm indiameter were common, making them very large compared to those of benthicnemerteans. Sperm possessed elongated heads and nuclei. In general, thepelagic nemerteans studied appeared: a) to produce relatively few maturegametes at a time, b) spawn in close proximity to each other, c) undergoiteroparous reproduction, and d) display moderately long-lived life cycles.In addition, data for P. cf. murrayi and possibly N. cf. mirabilisdemonstrates potential seasonal peaks in reproductive activity.     

Morphology and taxonomic distribution of a newly discovered feature,postero-lateral glands,in pelagic nemerteans

A variety of pelagic nemerteans from our collections off California and Hawaii between 1992 and 1997 have a pair of epidermal structures, usually visible on the intact specimens, located on the ventro-lateral margins near the caudal end of the body. The only previous reports of similar structures from pelagic or any other nemerteans are for two species of the genus Plotonemertes. Histological serial sections of at least one specimen from each of about 16 morpho-species demonstrate that these are specialized glandular regions of the epidermis, which we broadly term postero-lateral glands. The objects of this study are to describe these glands at the level of light microscopy and to consider their systematic implications and possible functions. Most of the glands consist of two more or less spatially segregated types of secretory cells. One type is usually at the anterior end of the gland and resembles typical mucous goblet cells. The other type usually is the more abundant, and resembles a nemertean serous cell, with secretion that probably is relatively proteinaceous. The glands of one of the Plotonemertes specimens have two additional types of secretory cells that are relatively abundant. This study reports on postero-lateral glands from 30 specimens: three specimens of Plotonemertes in the family Protopelagonemertidae, 18 in at least three genera of the family Pelagonemertidae, six in the monotypic family Balaenanemertidae, and three of Proarmaueria in the family Armaueriidae. The glands are relatively large, with large quantities of secretory vesicles, indicating that they must be of considerable importance to the animals. However, neither structure nor location offer self-evident clues to function of these glands. We also report on different forms of regional specialization in the epidermis of Crassonemertes and Nectonemertes, both of which lack postero-lateral glands.     

The nemerteans (Nemertea) of Rottnest Island, Western Australia

Seventeen species of marine nemerteans are reported from Rottnest Island, Western Australia. Eight new species and four new genera are described and illustrated; these are the heteronemerteans Kohnia rottnestensis gen. et sp. n., Lineus bioculatus sp. n., Lineus gilviceps sp. n., Micrura callima sp. n. and Uricholemma nigricans gen. et sp. n., and the monostiliferous hoplonemerteans Aenigmanemertes norenburgi gen. et spn. n., Crybelonemertes arenicolus gen. et sp. n. and Tetrastemma tristibruna sp. n. A key for the field identification of the nemerteans of Rottnest Island is provided.     

Global diversity of nemerteans (Nemertea) in freshwater

Most ribborn worms (phylum Nemertea) are marine and only 22 of the currently named around 1,200 species are known from freshwater habitats (mainly lakes/ponds). They are all free-living benthic forms found in all continents except Antarctica. The vast majority of species have been recorded from the Palearctic region, but this may reflect sampling efforts rather than biogeography. Guest editors: E.V. Balian, C. Lévêque, H. Segers & K. Martens Freshwater Animal Diversity Assessment     

Phylogenetic relationships and genetic distances between some monostiliferous interstitial nemerteans (Ototyphlonemertes, Hoplonemertea, Nemertea) indicated from the 16s rRNA gene

Part of the 16s rRNA mitochondrial gene is used to reconstruct the relationships within five populations (representing three currently recognized species) of interstitial nemerteans ( Ototyphlonemertes , Hoplonemertea, Nemertea), and to assess genetic divergence between representatives of these populations. The non-helicophoran individuals form a monophyletic sister-group to the helicophoran taxon, which further resolves a previous hypothesis based on morphological characters. The small nucleotide differences between some of the populations are within levels expected for panmictic populations and fail to distinguish them genetically; without applying a phylogenic perspective, some of the populations may be allocated into paraphyletic species assemblages.     

Dietary immunoassay of pelagic nemerteans by use of cross-reacting polyclonal antibodies: preliminary findings

With little data on the diet of pelagic nemerteans, apreliminary immunoassay survey of the gut contents ofthree species from the Pacific Ocean was performedusing non-specific, cross-reacting polyclonalantibodies. Results suggest that Nectonemertescf. mirabilis, Phallonemertes cf. murrayi, and Cuneonemertes elongata containedsomewhat different types of prey. Worms elicitedstrong responses when probed with antibodies tosquid-like mollusks and to mysids and shrimp. Heteropods are more likely ingested than pteropods. Additional studies must be done to confirm thesehighly suggestive results.     

A taxonomic catalogue of Japanese nemerteans (phylum Nemertea)

A literature-based taxonomic catalogue of the nemertean species (Phylum Nemertea) reported from Japanese waters is provided, listing 19 families, 45 genera, and 120 species as valid. Applications of the following species names to forms previously recorded from Japanese waters are regarded as uncertain: Amphiporus cervicalis, Amphiporus depressus, Amphiporus lactifloreus, Cephalothrix filiformis, Cephalothrix linearis, Cerebratulus fuscus, Lineus vegetus, Lineus bilineatus, Lineus gesserensis, Lineus grubei, Lineus longifissus, Lineus mcintoshii, Nipponnemertes pulchra, Oerstedia venusta, Prostoma graecense, and Prostoma grande. The identities of the taxa referred to by the following four nominal species require clarification through future investigations: Cosmocephala japonica, Dicelis rubra, Dichilus obscurus, and Nareda serpentina. The nominal species established from Japanese waters are tabulated. In addition, a brief history of taxonomic research on Japanese nemerteans is reviewed.     

Preliminary study of heat shock proteins in nemerteans

Nemerteans experience varying environmental temperatures during low tide exposures. Inducible heat shock proteins (hsps) have been reported for most organisms following both artificial heat stress and natural environmental temperature variations. This preliminary study reports the presence of hsps in the phylum Nemertea. A lethal temperature of 36 °C was determined for Paranemertes peregrina Coe, 1901. The nemerteans were exposed to a temperature of 34 °C for 2 h. After a 2 h recovery time, the worms were then analyzed for hsps by SDS–PAGE and western immunoblot protocols. Control worms were allowed to acclimate to ambient temperatures (13–15 °C) before hsp analysis. Hsp70 and hsp90 were detected in both the control and heat-shocked worms in highly variable concentrations, and the latter group had significantly elevated hsp70 levels. In addition, the analysis detected different isoforms of hsp70. The detection of hsps indicates a possible role in nemertean physiology during response to thermal stress, and potentially to other environmental challenges.     

Some nemerteans (Nemertea) from Queensland and the Great Barrier Reef, Australia

Three species of marine nemerteans described and illustrated from Queensland and the Great Barrier Reef, Australia, include one new genus and two new species: these are the monostiliferous hoplonemerteans Thallasionemertes leucocephala gen. et sp. nov. and Correanemertes polyophthalma sp. nov. A new colour variety of the heteronemertean Micrura callima is also reported, this species previously only being known from Rottnest Island, Western Australia. A key for the field identification of the marine nemerteans recorded from coastal Queensland and the Great Barrier Reef is provided.     

Giant pelagic larvae of Phyllodocidae (Polychaeta,Annelida)

The microscopic anatomy of giant pelagic larvae of Phyllodocidae was studied using routine histological, SEM, and TEM techniques. The larvae consist of two distinct regions: a large spherical trochophore measuring up to 2 mm in diameter and a posterior, long (up to 10 mm length), narrow rudiment of the adult body with up to 120 segments. The larvae have an unusual mixture of larval and adult features, including a very complex, well-developed brain and ganglia in the ventral nerve cord, and only a single pair of protonephridia located in the hyposphere of the trochophore. A muscular pharynx is not developed. The intestinal wall, especially in the trochophore region, consists of endodermal cells containing considerable nutritive material in the form of yolk-like globular inclusions. The digestive tract of all larvae was empty. The position of the frontal sensory organ and the prototroch, the structure of the parapodia and setae, and the three pairs of tentacular cirri dictate inclusion of the larvae in the family Phyllodocidae. The relatively enormous size and unusual pattern of development of the adult body may be adaptations for a long pelagic life and rapid settlement of the species, which inhabits slopes of islands and underwater mounts located far apart. J. Morphol. 238:93–107, 1998. © 1998 Wiley-Liss, Inc.     

Nemerteans of the Great Barrier Reef 6. Enopla Hoplonemertea (Polystilifera: Reptantia)

Two new genera and species of reptantic polystiliferous hoplonemerteans from the Great Barrier Reef province of Australia are described and illustrated. Urichonemertes pilorhynchus gen. et sp. nov. and Xenonemertes rhamphocephalus gen. et sp. nov. are both placed in the family Drepanophoridae (Polystilifera: Eureptantia: Aequifurcata).     

Morphology and systematics in mesopsammic nemerteans of the genus Ototyphlonemertes (Nemertea,Hoplonemertea, Ototyphlonemertidae)

Interstitial nemerteans of the genus Ototyphlonemertes are difficult to organize into traditional morphospecies. They occur in a multitude of slightly different local varieties that form a seemingly continuous morphological cline. In this paper, we summarize most published morphological data on the group, plus 73 new records of geographic varieties from the Mediterranean Sea in the East to the Sea of Japan in the West. We summarize morphological variation, partition traits into character and character states, propose a standardized protocol for examination of live specimens and discuss the phylogenetic structure of the group. The phylogenetic discussion leads to a hypothesis that partitions all varieties (including the established species) into six groups. These are the smallest morphologically homogenous sets of varieties (corresponding to traditional morphospecies) we can diagnose on phylogenetically reliable traits. Variation within the groups appears to be unreliable phylogenetic markers that may distinguish ecological forms rather than relatedness. However, we distinguish four of the groups by combinations of two traits, one apomorphy for a more inclusive group and one plesiomorphy, and the remaining two by one trait each that may be either a unique plesiomorphy or an apomorphy depending on the rooting, and most of them may thus join paraphyletic groups of cryptic monophyletic units. We call this kind of group phylomorph and name them the Duplex-, Pallida-, Cirrula-, Fila-, Lactea- and Macintoshi-morph (referring to the first established species within each group, i.e. Ototyphlonemertes duplex, O. pallida, O. cirrula, O. fila, O. lactea and O. macintoshi respectively). The phylogenetic scheme provides a simple tool to allocate geographical varieties to a group of possible `species' and a phylogenetic null-hypothesis for further tests with genetic data.     

Phylogenetic relationships inSecale (Poaceae): An isozymatic study

The genetic frequencies of 9 isozyme loci have been estimated in 23 samples of 4 species ofSecale by means of starch gel electrophoresis. The populations ofS. silvestre andS. vavilovii were monomorphic and uniform within each species, those ofS. montanum andS. cereale were polymorphic for most of the isozyme loci. On the basis of isozyme patterns as well as allelic and genotypic frequencies of isozyme loci,S. silvestre can be distinguished fromS. vavilovii, and both fromS. cereale andS. montanum; but there is no clear differentiation between the two latter species. Clusters constructed from genetic distances separateS. silvestre andS. vavilovii, whereasS. cereale andS. montanum were grouped together. The isozymatic data presented here, along with cytogenetic and life habit data, agree with the generally admitted existence of 4 species inSecale, and support the relationships suggested byKhush & Stebbins (1961).     

Exploring the molecular diversity of terrestrial nemerteans (Hoplonemertea, Monostilifera, Acteonemertidae) in a continental landmass

We report the finding of terrestrial nemerteans of the family Acteonemertidae from the northern part of Spain. The specimens were studied using molecular data from the nuclear ribosomal 18S rRNA and the mitochondrial cytochrome c oxidase subunit I genes. The 18S rRNA data strongly suggest the presence of three species of terrestrial nemerteans in the Iberian Peninsula, an old landmass where terrestrial nemerteans had not previously been reported. These specimens originate from primarily undisturbed forests across a distance of c . 1000 km. Cytochrome c oxidase subunit I data also indicate the presence of multiple lineages of Iberian terrestrial nemerteans. Nonetheless, the pattern obtained from this marker is obscured most probably by deep genetic divergences. This molecular diversity, at least in some of the clades, suggests that the Iberian species are not the result of recent introductions, as proposed for other terrestrial nemerteans found in Europe. Our data also touch upon the question of a single origin of terrestriality in nemerteans, a hypothesis rejected by both data sets. Nevertheless, terrestriality seems to have had a single origin in the family Acteonemertidae.     

Gibson's reclassification of the enoplan nemerteans (Enopla, Nemertea): a critique and cladistic analysis

Gibson's (1988) reclassification of the class Enopla (phylum Nemertea), and in particular the forming of the taxon Paramonostilifera, is assessed by a cladistic analysis based on 35 characters. This analysis does not support the reclassification, and it is suggested that the previous classification is kept for the time being, although it is recognized that certain of the higher categories are non-monophyletic and should be reclassified.     

Phylogenetic systematics of Archembiidae (Embiidina, Insecta)

Abstract. A cladistic analysis of the American genera of Embiidae is presented, using fifty‐seven representative taxa and ninety‐four morphological characters. The results support the elevation (and significant re‐delimitation) of the subfamily Archembiinae to family level; as delimited here, Archembiidae, revised status, includes the genera Ecuadembia n.gen., Calamoclostes Enderlein, Archembia Ross, Embolyntha Davis, Xiphosembia Ross, Ochrembia Ross, Dolonembia Ross, Conicercembia Ross, Neorhagadochir Ross, Pachylembia Ross, Rhagadochir Enderlein, Litosembia Ross, Navasiella Davis, Ambonembia Ross, Malacosembia Ross, Biguembia Szumik, Gibocercus Szumik and Pararhagadochir Davis. The results also indicate that some genera recently proposed are unjustified and therefore they are synonymized: Argocercembia Ross (a junior synonym of Embolyntha), Brachypterembia Ross (Neorhagadochir), Scelembia Ross (Rhagadochir), Ischnosembia Ross (Ambonembia) and Aphanembia Ross (Biguembia); all new synonymy. The new genus Ecuadembia is described (type species Archembia arida Ross). Ischnosembia surinamensis (Ross) is returned to the genus Pararhagadochir. The following species synonymies are established: Archembia lacombea Ross 1971 = Archembia kotzbaueri (Navas 1925), Archembia peruviana Ross 2001 = Archembia batesi (MacLachlan 1877), and Conicercembia septentrionalis (Mariño & Márquez 1988) = Conicercembia tepicensis Ross 1984; all new synonymy. The family Archembiidae, and all its constituent genera, are diagnosed and described. The genus Microembia Ross (originally described as an Embiidae) is transferred to Anisembiidae. Pachylembiinae, Scelembiinae, and Microembiinae proposed by Ross are unsupported by the present cladistic analysis. 1