REVISION OF MEZIA (MALPIGHIACEAE)

The Neotropical genus Mezia (Malpighiaceae) comprises 15 species of lianas (except M. huberi W.R.Anderson, a shrub or small tree). All have multibranched, densely brown-sericeous inflorescences with the ultimate unit a 4-flowered umbel of bilaterally symmetrical flowers. The distinctive pair of large cymbiform bracteoles subtends a rudimentary pedicel and encloses the floral bud. The flowers contain elongate sepals, the lateral four biglandular, yellow petals, the posterior often splotched with red, a heteromorphic androecium, and a tricarpellate gynoecium. The three styles are all free; the posterior pair is lyrate in five species but erect in the others. The samaras have an orbicular to oblate lateral wing and a much smaller dorsal wing; in most species, additional winglets and/or crests are present between the lateral and dorsal wings. Only Mezia mariposa W.R.Anderson has butterfly-shaped samaras lacking additional ornamentation. Four new species are proposed: Mezia andersonii C.E.Anderson, M. bahiana C.E.Anderson, M. fanshawei C.E.Anderson and M. sericea C.E.Anderson. One variety is elevated to species level and provided with a new name, Mezia peruviana C.E.Anderson; a lectotype is chosen for Diplopterys involuta var. ovata Nied. Full descriptions and synonymies are provided, as well as a distribution map. All species are illustrated.

A new sibling species of Notobryon (Gastropoda, Nudibranchia) from the Caribbean Sea

A new Scyllaeidae of the genus Notobryon is described from Guadeloupe, in the Lesser Antilles. Notobryon caribbaeus sp. nov. is characterized by having the anterior pair of body lobes remarkably bigger than the posterior pair, a stomach with eight triangular plates, a black and very wide ampulla, a lemon-shaped bursa copulatrix and a complex and well-differentiated sponge-like prostate. The first Caribbean records of Notobryon were provisionally assigned to the Australian species Notobryon cf. wardi and later transferred to Notobryon panamica. However, the structure of the male genital system is one of the main morphological characters to discriminate species in the genus and the presence of a prostate in N. caribbaeus sp. nov. distinguishes it from N. panamica, which remains confined to the eastern Pacific. Of the remaining four species in the world, only Notobryon bijecurum shares this character, but its external anatomy is different: it lacks a bursa copulatrix and the deferent duct is much shorter. Notobryon caribbaeus sp. nov. was captured in the context of an intensive expedition (‘Karubenthos’) organized by the Muséum National d'Histoire Naturelle, Paris and its description raises the total inventory of sea slugs in Guadeloupe to 150.

The first sexually dimorphic species of Oribatella (Acari, Oribatida, Oribatellidae) and a review of sexual dimorphism in the Brachypylina

The oribatid mite genus Oribatella includes over 100 named species, none of which shows distinct sexual dimorphism in the octotaxic system of dermal glands. We propose a new species of this genus, Oribatella canadensis sp, nov., collected from dry soil habitats in western Canada, that shows distinct dimorphism in these dermal glands, the first record of this dimorphism in the Oribatelloidea. The posterior pair of glands in males, but not females, is enlarged and associated with a shallow, medial pit-tubercle complex, and is generally similar to convergent dimorphisms in some genera of Mochlozetidae (Oripodoidea), Mycobatidae (Ceratozetoidea) and Galumnidae (Galumnoidea). We describe this species based on adult and nymphal stages, and expand the diagnosis of the genus to accommodate the newly described immatures. We review the expression of sexual dimorphism in brachypyline oribatid mites and discuss its association with periodically dry habitats.

Morphology, molecular characterisation and systematic position of Hemiplectus muscorum Zell, 1991 (Nematoda: Plectida)

Hemiplectus muscorum, the type and single representative of its genus, is redescribed on the basis of abundant new material collected in the UK, Canada and the USA using both light and scanning electron microscopy. The phylogenetic relationships of the species are inferred from morphological as well as molecular data. Maximum parsimony, neighbour joining and maximum likelihood analyses of small subunit (SSU) rRNA sequences support a position nested among the Plectidae. This conflicts with our morphological assumptions of character polarity, as it implies that the absence of a valvate bulb in Hemiplectus is a reversal rather than a plesiomorphy. The excretory system of Hemiplectus is described more precisely. Its structure is highly reminiscent of the system in Plectus but differs in the presence of an anterior and posterior pair of pseudocoelomocytes flanking the renette cell. A pair of lateral somatic setae is identified as possible homologues of the 'deirids' in Plectus and Rhabditida. Measurements and descriptions are given of all four juvenile stages.

A new species of Cosmocerca (Nematoda, Cosmocercidae) and other helminths from Genyophryne thomsoni (Anura, Microhylidae) from Papua New Guinea

Cosmocerca tyleri sp. nov. (Ascaridida, Cosmocercidae) from the large intestine of Genyophryne thomsoni (Anura, Microhylidae) is described and illustrated. Cosmocerca tyleri sp. nov. represents the 23rd species assigned to the genus and the 6th from the Australian realm. Of the 5 Australian species previously described, C. tyleri sp. nov. differs from C. limnodynastes and C. novaeguineae in number of plectanes, 4 pairs in C. tyleri, 5 pairs in C. limnodynastes and C. novaeguineae. Cosmocerca australis has 3–4 pairs of plectanes, C. archeyi and C. zugi each have 4 pairs of plectanes; however, in each species the plectanes lie in the fourth quarter of the body and just anterior to the cloaca. In C. tyleri sp. nov. the plectanes lie in the third quarter of the body and there is significant space between the cloaca and the posterior pair of plectanes.

The Drosophila EGF receptor homologue (DER) is required for Malpighian tubule development

Defects in the locus Egfr, encoding the Drosophila EGF receptor homologue (DER), affect the development of the Malpighian tubules. They form as much shorter structures than in wild-type embryos, containing a reduced number of cells. The severity of this phenotype in seven alleles that we have analysed correlates with other embryonic defects caused by Egfr mutations. Interestingly the two pairs of tubules are affected with different severity, with a greater reduction in cell number in the posterior pair than in anterior. Temperature shift experiments indicate a role for this receptor in the regulation of tubule cell division. We also suggest that an additional role for DER in the allocation of cells to the tubule primordia is possible.

Scorpions from the Viséan of East Kirkton, West Lothian, Scotland, with a revision of the infraorder Mesoscorpionina

ABSTRACTScorpions from East Kirkton Quarry are represented by abundant cuticle fragments and rarer articulated specimens. Cuticles isolated from their matrix are exquisitely preserved, permitting this fauna to be described in more detail than other Carboniferous scorpion faunas. Most of the material is attributed to Pulmonoscorpius kirktonensis n. gen. n. sp. Specimens possibly indicating the presence of two additional Pulmonoscorpius species are referred to under open nomenclature. Rare fragments of an aquatic ‘archaeoctonoid’, and an orthostern scorpion, also occur. Most specimens of Pulmonoscorpius are juveniles. The range of taphonomic effects observed in these and larger individuals suggests that, as a consequence of poor preservation, the morphology of some Upper Palaeozoic scorpions has been misinterpreted by previous workers. Within the infraorder Mesoscorpionina two groups are recognised. These are distinguished by the position of the posterior pair of coxae. Pulmonoscorpius n. gen. belongs to group A, in which the posterior coxae abut the sternum. This group includes the known Lower Carboniferous mesoscorpions and ranges from the Upper Devonian to the Upper Carboniferous. All group-A mesoscorpions are reviewed here. In group-B mesoscorpions the posterior pair of coxae apparently abut the genital opercula, but confirmation of this derived character and formal taxonomic recognition of these groupings must await a restudy of the group-B mesoscorpions, which are known from the Upper Carboniferous and Triassic.

The eggs and oncomiracidia of Encotyllabe spp. and the relationship between encotyllabines and other capsalid monogeneans

SUMMARYThe eggs and oncomiracidia of two species of the capsalid genus Encotyllabe are described. These parasites were identified tentatively as E. caballeroi Velasquez, 1977 and E. caranxi Lebedev, 1967. If these identifications are correct, then E. caballeroi is recorded from two new hosts, Gymnocranius audleyi and the nemipterid Scolopsis monogramma, and E. caranxi from a new host, Pseudocaranx dentex, and a new locality, Heron Island, Queensland, Australia. Encotyllabines have not previously been recorded from fishes of the family Nemipteridae. The eggs of the two parasites failed to hatch spontaneously and did not hatch when exposed to a variety of potential hatching stimuli, but the oncomiracidia within survived for many weeks. Oncomiracidia expelled from eggs by cover-slip pressure are unciliated and possess a saucer-shaped haptor like that of other capsalids with three pairs of median sclerites and 14 marginal hooklets. The paths of tendons associated with the accessory sclerites and the presence of haptoral loculi suggest that encotyllabines are related to the trochopodines. Observations on a single juvenile specimen of E. caballeroi show that the accessory sclerites and the tendons are lost early in development and that one pair of hamuli (probably the posterior pair) ceases to grow early in post-oncomiracidial life. The loculi persist a little longer but also disappear before full sexual maturity is reached.

A Malpighian Tubule Lime Gland in an Insect Inhabiting Alkaline Salt Lakes

The alkali fly, Ephydra hians Say, inhabits alkaline salt lakes which can contain concentrations of dissolved carbonate and bicarbonate as high as 500 mmol l−1. Larvae of the alkali fly possess two pairs of Malpighian tubules. The posterior pair has a morphology similar to that of the tubules of most other insects, but the anterior pair is modified into an enlarged gland containing white microsphere concretions. We describe the ultrastructure of all cell types in both pairs of tubules. Using scanning electron microscope (SEM) X-ray microanalysis and chemical CO2 quantification, we demonstrate that the concretions in the lime glands are composed of nearly pure calcium carbonate. Isolated preparations of lime gland tubules accumulate 45Ca significantly more rapidly than do normal tubules. Although similar to the rime concretions found in the Malpighian tubules of other Diptera, the lime glands of this insect may function to regulate the high concentrations of carbonate and bicarbonate encountered in their aquatic environment. It is proposed that the mechanism of this regulation may be chemical precipitation of carbonate/bicarbonate with calcium in the lumen of these specialized lime gland tubules.