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     

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.     

Polymorphism hides cryptic species in Oerstedia dorsalis (Nemertea, Hoplonemertea)

The marine hoplonemertean Oerstedia dorsalis is considered to be a highly polymorphic species with extensive geographic distribution. We show, based on mitochondrial cytochrome c oxidase subunit I, 16S and nuclear internal transcribed spacer sequences, that there are genetic subsets withing this species. Seventy-one specimens of various colours from different geographic localities (in Europe) were sequenced and analysed using statistical parsimony and Bayesian analysis. Both analyses supported nine major clades. We conclude that O. dorsalis hides different species with geographic resolution. These species, however, appear to be polymorphic as well, and we find no diagnostic features in pigmentation or external characters to separate species within this complex.  © 2009 The Linnean Society of London, Biological Journal of the Linnean Society , 2009, 98 , 556–567.     

Larval development of nemerteans of the genus Quasitetrastemma (Nemertea: Monostilifera)

Data on the larval development of Quasitetrastemma stimpsoni and Q. nigrifrons are presented. In both species, fertilization is external; the development passes through a free-swimming larval stage, the “hidden larva.” The larva has three pairs of eyes. After settling, the eyes of the second pair fuse with eyes of the first pair or are completely reduced. The basis and stylets are formed in 7–8 days after fertilization. Larvae of Q. stimpsoni settle on day 9–10 after fertilization; and Q. nigrifrons, on day 7–8.     

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.     

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.     

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.     

The species composition of the nemertean genus Oerstedia (Nemertea: Hoplonemertea) in the Far Eastern seas of Russia

According to the literature, six species of nemerteans of the Oerstedia genus occur in the Far Eastern seas of Russia. The results of genetic (28S) and allozyme (11 loci) analysis revealed that O. oculata (Kulikova, 1987), O. zebra (Chernyshev, 1993) and O. valentinae (Chernyshev, 1993) are junior synonyms of O. polyorbis Iwata, 1954, while O. phoresiae (Kulikova, 1987) is a valid species. The species validity of O. dorsalis sensu Iwata, 1954 was also corroborated. New data on the variability and distribution of certain nemerteans are furnished.     

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.     

A phylogeny of Vesiculariidae (Bryozoa,Ctenostomata) supports synonymization of three genera and reveals possible cryptic diversity

Compared to their calcified sister group, order Cheilostomata, uncalcified ctenostome bryozoans exhibit relatively simple and often inconsistent morphologies, making them particularly suitable candidates for the use of molecular tools to delimit species and examine their interrelationships. The family Vesiculariidae is composed of six genera, three of which, Zoobotryon, Avenella and Watersiana are monotypic, and one, Vesicularia, encompasses four species. The majority of vesiculariid diversity, however, is found in Amathia (39 species) and Bowerbankia (21 species). The respective monophyletic status for Amathia and Bowerbankia has recently been put into question by molecular evidence and is being further examined in this study. Multigene (ssrDNA, rrnL, cox1) phylogenetic analysis revealed that Bowerbankia is paraphyletic to the inclusion of Zoobotryon and Amathia, where the latter was resolved as non‐monophyletic. Although Vesicularia also nested within this paraphyletic assemblage in some of the analyses, Bayesian topology testing did not support this result. Our results are discussed within the context of published morphological evidence and lead to the conclusion that Bowerbankia and Zoobotryon should be classified as junior subjective synonyms of Amathia. A revised nomenclature is provided. Furthermore, we examined genetic divergences between widely distributed supposed conspecific species and discovered possible cryptic diversity in the outgroup taxon Anguinella palmata and in Bowerbankia citrina, Amathia vidovici and Amathia crispa.     

Intraspecific life-history variation in Radix plicatulus (Gastropoda: Pulmonata: Lymnaeidae)

Life-histories of Radix plicatulus (Benson, 1842) populations inhabiting two neighbouring sites on a Hong Kong stream were investigated. In one of the two sites, R. plicatulus co-occurred with high densities of Pomacea levior which is known to prey on the egg capsules and hatchlings of sympatric gastropods. On the basis of general life-history theory, I hypothesized that R. plicatulus which co-occurred with P. levior should exhibit a life-history strategy characterized by a delayed reproduction, a longer recruitment period and a larger number of breeding bouts per year as compared with contemporaries inhabiting the other site with low P. levior abundance. Reproductive patterns of the two populations observed in the field accorded with the expectations of general life-history theory, and lent support to the hypothesis. However, laboratory culture experiments revealed no evidence of a genetic basis for the interpopulation differences. The importance of establishing a genetic basis for the interpopulation divergence before invoking an evolutionary explanation was discussed.     

Intraspecific volatile oil variation in Myrceugenia cucullata (Myrtaceae)

The analysis of volatile oil content of Myrceugenia cucullata, a treelet from southern Brazilian montane forests, was investigated. Two markedly distinct chemotypes were identified. One of them is dominated by (E)-nerolidol and the other by (−)-α- and (−)-β-pinenes. Field observations showed a distinct ecological behaviour of plants with distinct chemical compositions, and a closer morphological analysis hints to a possible separation of them. The diverse oil composition is discussed and the possibility of specific segregation of the chemotypes is commented.     

The caudal skeleton of ostariophysan fishes (Teleostei): Intraspecific variation in trichomycteridae (Siluriformes)

The different elements of the caudal skeleton of the South American catfish genera Nematogenys (Nematogenyinae) and Trichomycterus, Hatcheria, and Bullockia (Pygidiinae) (Siluriformes, Trichomycteridae) show Ontogenetic transformation of the second ural centrum in Trichomycteridae separates the subfamilies Nematogenyinae and Pygidiinae. In the former, the second ural centrum is aligned with the first ural centrum in early stages of ontogeny; it is not fused with the bases of hypurals 3 and 4 in any stage of development. In the Pygidiinae, in contrast, the second ural centrum is connected with the base of hypural 3 from an early stage of development on. One of the most noteworthy features of the Pygidiinae is the epural, a polymorphic element with three or four morphotypes that are species specific. The primitive catfish Nematogenys shows intraspecific variation in the ural centra, segmentation of procurrent caudal rays, and principal caudal ray formulae. Species of Trichomycterus, Hatcheria, and Bullockia are characterized by great intraspecific variability that involves ural centra, the epural, hypurapophyses, and the neural arches of the compound centrum. There is intraspecific variation in the fusion of the hypurals in some species of Trichomycterus. Intraspecific variation of the caudal skeleton of fishes of the family Trichomycteridae involves the presence and frequency of different morphotypes of the epural, neural arch of the compound centrum, fusion of hypurals, and principal caudal ray formulae. Ontogenetic changes of the first and second ural centra, hypurapophyses (with the exception of Nematogenys), and segmentation of procurrent caudal rays (in Nematogenys) are involved also.     

Intraspecific variation in wing and pupal melanization in copper butterflies (Lepidoptera: Lycaenidae)

Melanin is a widespread pigment causing variation in skin darkness, with darker phenotypes typically reaching higher equilibrium temperatures than lighter ones. Therefore, selection is expected to favour darker phenotypes in colder environments. In the present study, we show intraspecific variation in pupal (and wing) melanization along an altitudinal gradient in two species of copper butterflies. Both, pupal and wing melanization increased with increasing altitude. Consistent with the thermal melanism hypothesis, darker (high-altitude) pupae reached higher equilibrium temperatures than paler (low-altitude) ones. However, as temperature differences were rather small despite pronounced differences in melanization, we cannot rule out that factors (e.g. ultraviolet protection, disease resistance) other than temperature comprise the principal selective agents. Mechanistically, variation in melanization might be related to variation in hormone titres, as demonstrated by low-altitude pupae showing higher ecdysteroid and juvenile hormone titres compared to high-altitude ones. Furthermore, we report sex differences in wing melanization, with males being darker than females, which is potentially related to a higher flight activity of males.  © 2009 The Linnean Society of London, Biological Journal of the Linnean Society , 2009, 98 , 301–312.     

Intraspecific morphological variation with biometry of Distephanus speculum (Silicoflagellata)

Living specimens of Distephanus speculum (Silicoflagellata) were collected in waters of <150 m depth in the Pacific Sector of the Southern Ocean (57°31.6′S, 150°02.9′E), South of Tasman Island, and a biometric study has been conducted. The skeleton of D. speculum has a simple morphology, which can be readily expressed quantitatively. Using a new methodology, repeated measurements were obtained and converted to numerical indices. The circumference of the basal rings was the most useful character for subdivision into groups, and using this parameter we recognized two populations in the 620 studied specimens: (1) 500 individuals were placed in Group A, with a basal ring circumference of 53 to 67 µm, and a difference in length of spine axes from 2 to 6 μm; and (2) 120 individuals were placed in Group B (basal ring circumference 80 to 105 µm, difference in length of spine axes 3 to 6 µm). The circumference of the basal ring in Group B is approximately 10 µm smaller than in Distephanus speculum giganteus [Bukry, D., 1979. Comments on opal phytoliths and stratigraphy of Neogene Silicoflagellates and Coccoliths at Deep Sea Drilling Project Site 397 off Northwest Africa. Initial report of the DSDP, Washington, 49:977–1009.], and Distephanus boliviensis [Bukry, D., 1976a. Silicoflagellate and coccolith stratigraphy, Norwegian–Greenland Sea. Initial Report of DSDP LEG 38. Initial report of the DSDP, Washington, 38:843–855.; Bukry, D., 1976b. Silicoflagellate and coccolith stratigraphy, southeastern Pacific Ocean, Deep Sea Drilling Project Leg 34. Initial report of the DSDP, Washington, 34:715–735].     

A new monostiliferous hoplonemertean (Nemertea), Oerstedia striata sp.n., from the west coast of Sweden

Oerstedia striata sp.n. (family Prosorhochmidae?) is described. The species was originally reported as one of the varieties of the polymorphic species Oerstedia dorsalis (Abildgaard, 1806). Its specific status was detected by an electrophoretic screening of six enzymes, of which four were unique for this species as compared to the analysed forms of O. dorsalis.     

Intraspecific variation and evolutionary trends of Alicornops simorrense (Rhinocerotidae) in Spain

The Spanish material of Alicornops simorrense constitutes the best representation of the species in Western Europe. It provides interesting data on the metrical and morphological intraspecific variation of A. simorrense and its evolutionary trends from late Middle Miocene to the early Late Miocene. From late Aragonian to early Vallesian, a slight increase in size is observed, but without clear limits among series. During the late Vallesian, A. simorrense evolved in central Spanish basins into a second species, A. alfambrense, greater in size and with more robust proportions. In the Vallés-Penedés basin, A. simorrense shows a noticeable increase in size, while maintaining its proportions, during the Vallesian. A. simorrense was a very abundant species, an open woodland dweller, with gregarious behaviour, whose extinction was probably linked to the climatic change that took place at the end of the Vallesian and the beginning of the Turolian.     

Intraspecific and interspecific variation in drumming signals in the genus Capnioneura (Plecoptera: Capniidae)

The male drumming calls of four species of the genus Capnioneura, and for the first time, the female answer signal from one species of this genus are described. Only the male call of C. mitis from a southern Iberian Peninsula is known. In the current study, the male calls of three additional C. mitis populations from two different mountain drainages and the male calls of C. gelesae, C. libera and C. petitpierreae are described and analysed. The calls were near-ancestral and percussive signals with variable numbers of beats and approximately constant, monophasic beat intervals. The mean interbeat intervals were species specific, ranging from 250 to 1500 ms. The C. mitis female answer interbeat intervals were similar to the call but composed of 3–4 beats. Intraspecific and interspecific variation is discussed and these results support the hypothesis that stonefly drumming plays an important role as a reproductive isolating mechanism.