Papillonema danieli gen. et sp.n. and Papillonema clavatum (Gerlach, 1957) comb.n. (Nematoda,Desmodoridae) from the Ceriops mangrove sediments of Gazi Bay,Kenya

A new genus, Papillonema gen.n., is erected to accomodate the two species P. danieli gen. et sp. n. and P. clavatum (Gerlach, 1957) comb.n. from intertidal sediments of a tropical mangrove. Papillonema gen.n. is characterized by prominent papilliform labial sensillae, an elongate muscular terminal bulb (up to 60% of pharyngeal length), and three precloacal supplements. Comments are given on the use of the terms head capsule, head region, and cervical setae.Abbreviations a: body length divided by maximum body diameter - abd: anal body diameter - amph %: diameter of the amphid as a percentage of the corresponding head diameter - aw: amphidial width - b: body length divided by pharyngeal length - bdcs: body diameter at level of the cephalic setae - bdnr: body diameter at level of nerve ring - c: body length divided by tail length - cs: length of cephalic setae - da: distance from anterior to anus - dcs: distance from anterior edge to cephalic setae - dnr: distance from anterior edge to nerve ring - dv: distance from anterior to vulva - gub: length of the gubernaculum - hw: head width - L: body length - Isp: length of sperm cells - mbd: maximum body diameter - mbd ph: body diameter at level of pharynx - ph: pharyngeal length - spic: length of spicules measured along the arc - t: tail length - tmr: length of non-annulated tail end - V: position of vulva as a percentage of the total body length from anterior - wsp: width of sperm cells     

Phylogenetic relationships within the superfamily Desmodoroidea (Nematoda: Desmodorida), with descriptions of two new and one known species

Three nematode species of the superfamily Desmodoroidea Filipjev, 1922, were isolated from beach sediments in Wellington, New Zealand, for morphological and molecular analyses. Two of these species, D esmodorella verscheldei sp. nov. and D racograllus ngakei sp. nov. , were new to science and are described herein. Epsilonema rugatum Lorenzen, 1973, comb. nov. , which was originally described from New Zealand material as a subspecies of Epsilonema dentatum from Chile, is redescribed and elevated to the rank of species based on cuticular ornamentation. The phylogenetic relationships amongst the three Desmodoroidea families are investigated based on new and existing sequences of the D2 and D3 expansions segments of large subunit (LSU) 28S rRNA gene and small subunit (SSU) of 18S rDNA gene. Our analyses suggest that the Draconematidae is a sister taxon to the Desmodorinae and Spiriniinae, with the Draconematidae forming a monophyletic crown group and the Desmodorinae and Spiriniinae forming a paraphyletic stem group. Phylogenetic relationships between the Epsilonematidae and Stilbonematinae, however, could not be determined with certainty. The SSU and D2‐D3 of LSU consensus trees indicate that the morphological resemblance between the Draconematidae and Epsilonematidae, which are both characterized by swollen pharyngeal body regions and mid‐posterior body regions with specialized setae, reflects distinct and independently evolved adaptations to their unusual mode of locomotion, with differences in the structure and distribution of specialized setae between the two families also consistent with convergent evolution. We show that the family Desmodoridae and superfamily Desmodoroidea as currently defined are not monophyletic. It was not possible to determine whether the Prodesmodorinae are more closely related to the Desmodoroidea or Microlaimoidea, although it is clear that they do not belong to the Desmodoridae. The single Molgolaiminae sequence available formed a distinct clade together with the superfamily Microlaimoidea, and should therefore be placed with the latter. Clarifying the phylogenetic relationships within the Desmodoroidea will require greater focus on the Pseudonchinae, Molgolaiminae, and Epsilonematidae, for which no or very few sequences are available at present. © 2016 The Linnean Society of London     

Leptonemella species (Desmodoridae, Stilbonematinae), benthic marine nematodes with ectosymbiotic bacteria, from littoral sand of the North Sea island of Sylt: taxonomy and ecological aspects

Leptonemella species represent a dominant element of the nematode fauna in sulfidic, deep sediment layers on the sandy shore of Sylt. Based on collections sampled here in 1991–1999, a taxonomic treatise is presented on the three co-existing species, Leptonemella aphanothecae Gerlach, 1950, the closely related L. vicina sp. nov., and L. gorgo Gerlach, 1950. The high incidence of pseudohermaphrodites in the material, mostly functional females with a male copulatory apparatus, is remarkable. The highest population densities of Leptonemella spp. (up to 73 individuals/10 ml sand) were found near polychaete burrows. Because of the great spatial and temporal variations in the oxygen/sulfide regime of these microhabitats, and because of the strong adhesive capabilities of Leptonemella spp., which can anchor themselves firmly to sand grains using caudal glands, we propose that a hemisessile life strategy is employed by these nematodes to fulfill the metabolic needs of their sulfide-oxidizing ectosymbionts. Communicated by K. Reise