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A recent electrical penetration graph (EPG) study identified a unique intracellular puncture that is associated with inoculation of the semipersistently transmitted, phloem-limited Beet yellows virus (BYV, Closterovirus) by the aphid Myzus persicae. This new aphid EPG pattern (named phloem-pd) always occurs shortly before phloem sieve element phase (PSEP) and has a similar voltage drop as PSEP, both of which are less than the voltage drop of standard-pds. Structure of pd subphase II-2 differs between phloem-pds and standard-pds. The objective of this study was to determine the type of phloem cell penetrated during phloem-pds. Stylets of M. persicae feeding on sugar beet (Beta vulgaris) were fixed in situ by cryofixation during phloem-pds, standard-pds and PSEP waveform E1. The cell penetrated by the stylet tips was then identified by confocal laser-scanning microscopy and micro-computed tomography. Sieve elements (SEs) or companion cells (CCs) were penetrated during phloem-pds, whereas cells other than SEs or CCs (mesophyll, bundle sheath cells and possibly phloem parenchyma) were penetrated during standard-pds. SEs were penetrated during waveform E1. The implications of these findings for inoculation of other phloem-limited viruses that currently are thought to be inoculated primarily during waveform E1 are discussed.

15 pages, 14 figures, 2 tables, 1 appendix, We studied the anatomy and cytology of the midgut gland (MGl) of the common spider crab Maja brachydactyla Balss, 1922 at several life stages (zoea, megalopa, first juvenile, and adult) using dissection, histology, electron microscopy, computed tomography, and micro-computed tomography (micro-CT). In newly hatched larvae, 14 blind-end tubules form the MGl. The length of the tubules increases during the larval development. In the late megalopa, the number of tubules also increases. In adults, 35,000 to 60,000 blind-ending tubules comprise the MGl. In all life stages, a square-net network of muscle fibers surround the tubules. We describe five cell types in the MGl in all larval stages, which have a similar location, histology, and ultrastructure in larvae and adults: embryonary (E-) cells, resorptive (R-) cells, fibrillar (F-) cells, blister-like (B-) cells, and midget (M-) cells. Major difference between larval and adult cells is the larger size of the adult cells. Microapocrine secretion occurs from the microvilli of the B-cells. No ultrastructural changes were observed during larval development, which suggests that the function of each cell type might be similar in all life stages. The role of each epithelial cell type in larvae and adults is discussed, Financial support was provided by the Spanish Ministry of Economy and Competitiveness through the INIA project [grant number RTA 2011-00004-00-00] to G.G and a predoctoral fellowship to D.C. [FPI-INIA].

In Hemiptera, presumptive stylets for each consecutive postembryonic instar are manufactured prior to ecdysis to replace the ecdysial stylets discarded with the exuviae. With the discovery that the bacterium “Candidatus” Liberibacter solanacearum accesses the tissues involved in the stylet replacement process of the potato psyllid, a hypothesis was formed that the bacterium could adhere to the stylets of freshly emerged instars and hence gain access to the host plant when feeding is resumed. Although unproven, it was imperative that a model for stylet replacement be built. Stylet morphology and the stylet replacement process of the Asian citrus psyllid (ACP), vector of “C.” L. asiaticus, causal pathogen of citrus greening disease, are comparable to the potato psyllid model system. Morphology consists of a basal terminus with its tab-shaped auricle, a base, shaft, and an apical terminus. Each of the four auricles act as a platform for the replacement apparatus, which is compacted into a tight aggregate of cells, the ‘endcap’. As modeled, on apolysis of larval instar hypodermis, the aggregate ‘deconstructs’ and expands into a snail shell-shaped tube, the ‘atrium’, that houses the presumptive stylet as it is synthesized. Completed stylets then despool from the atrium and are fitted into their functional positions as the next instar emerges from its exuviae., Funding was provided by a grant from USDA-NIFA Award 2014- 70016-23028, 2015-2020, “Developing an Infrastructure and Product Test Pipeline to Deliver Novel Therapies for Citrus Greening Disease”.

The nymphal biology of a population of Torleya major (Klapalek) in southern Iberian Peninsula was studied. An atypical life cycle pattern is described, with eggs hatching in August producing a fast-developing cohort with adults emerging in autumn and a second slow-developing cohort with adults emerging in spring of the following year. Nymphal growth occurred primarily in summer–autumn (in the first cohort) and in spring (in the second). The origin of such a life history is discussed. Nymphs were collector-gatherers, consuming mainly detritus. Although ontogenetic shifts on the use of trophic resources were detected, similar food was utilized during the months when both cohorts cohabited, eliminating the possibility that the rapid growth of the first cohort could be related to the utilization of different food resources.

Burrowing is a common behavioural adaptation of lotic freshwater invertebrates to avoid the effects of current. This behaviour is accompanied by morphological adaptations. This also applies to the larvae of the stonefly Leuctra geniculata (Stephens, 1836) and the mayfly Ephemera danica Muller, 1764, both colonising habitats within the substrate and adapted to burrow in it. We have studied their life cycles and their relation with water temperature and day-degrees, feeding and secondary production. The stonefly had a univoltine life cycle with a larval development of 8 months and with an egg incubation period longer than previously reported. The possibility of an egg diapause stage is discussed. The mayfly was semivoltine, completing its larval development in 22 months. Both species mainly fed on detritus, but also ingested a high quantity of CPOM and some other minor components. Annual secondary production in both species was relatively high, being higher in the stonefly.

As a result of studies of material of Ecdyonurus from Spain, nymphs and adults of two new species, E. baeticus sp. n. and E. olgae sp. n., are described. Three species described by Navas must be considered as nomina dubia (E. diversus Navas, 1923, E. excelsus Navas, 1927 and E. fluminum var. speciosus Navas, 1915). Variability in adults of E. venosus is figured and discussed.

After an intensive study, we concluded that the species described by Alba-Tercedor and Sanchez-Ortega (1982) from the foothills of the Sierra Nevada mountains in Southern Spain as Torleya cf. belgica, actually belongs to a new species which we name Torleya nazarita sp. n. The new species is closely related to Torleya major (Klapalek, 1905), which up to now was considered to be the only European representative of the genus. Description and figures of the nymph and imago and the features distinguishing the new species from other species of the genus are given.

A new species of Hydropsyche of the instabilis-group, H. fontinalis sp. n., from the southern Iberian Peninsula is described. Diagnostic features of the male, female and larva (5th instar) are described and illustrated, and additional information on larval habitat and ecological notes are included.

The nymph and egg of Acentrella almohades sp. n. are described and illustrated on the basis of material collected in southern Spain (in the upper reaches of the Guadalquivir River Basin) and Morocco (Rif Mountains and Atlas Mountains). Features distinguishing the new species from other European species are discussed and keyed.

J. ALBA-TERCEDOR: Description of the Imagines of Rhithrogena goeldlini Sartori and Sowa, 1988, and Keys for the Identification of Imagines of the European Species of the R. diaphana-subgroup (Ephemeroptera: Heptageniidae). Aquatic Insects, Vol. 20, 1998, No. 2, pp. 125‐130. The male and female imagines of Rhithrogena goeldlini Sartori and Sowa, 1988 are described and drawn on the basis of material collected in Portugal close to the type locality. Features distinguishing male imagines of the European species of the R. diaphana-subgroup are keyed.

A new colour pattern of the larva of Rhyacophila meridionalis is described and compared to the larval kinds of this species known up‐to‐now and to the other larvae belonging to subgenus Rhyacophila s.s. Some ecological notes on the locality in the Iberian Peninsula where these larvae were found are included.

After a study of the type material of Baetis nexus Navas, 1918 and a comparison with Hungarian specimens of Baetis pentaphlebodes Ujhelyi, 1966 it is concluded that the two nominal species are synonyms and that B. nexus is the valid name.

The nymph and male imago of Caenis nachoi sp.n., a new species of the Caenis macrura group, from southern Spain are described and drawn, and biological data are included. Differences with closely related species (especially with C.macrura Stephens, 1835 and C.martae Belfiore, 1984) are discussed, and keys for the identification of the European species of the macrura group are included.

The Rfo Monachil, a high‐mountain stream in Sierra Nevada (South of Spain), was investigated. As a consequence of sewage discharges from a ski resort situated at the head of the stream and from populations along its banks, the river is affected by organic pollution. With the objective of finding what physico‐chemical factors determined the distribution of the Ephemeroptera and Plecoptera along the course of the stream, and in what manner they were affected, a stepwise multiple‐regression analysis was applied. Through this analysis it was possible to prove that, in general, the distribution and abundance of these two orders of insects in the Rfo Monachil are influenced by organic pollution. Nevertheless, at the species level other factors assume prime importance, such as temperature, oxygenation and mineralization of the waters, parameters which may or may not be related to pollution.

The full‐grown larva of Rhyacophila (Rhyacophila) nevada Schmid, 1952, is described and illustrated. The paper includes a key to the larvae of the species of Rhyacophila s.s. so far known from the Iberian Peninsula.

The recent description of Drunella andaluciaca Kazanci, 1990 (from the Sierra Nevada Mountains in southern Spain) was compared with the original description and with typical and additional material of Ephemerella (Chitonophora) nevadensis Alba‐Tercedor, 1983 (a species widespread in the Sierra Nevada Mountains). Accordingly, Drunella andaluciaca Kazanci, 1990 is transferred to the genus Ephemerella Walsh, 1862 and synonymy between Ephemerella andaluciaca (Kazanci, 1990) and Ephemerella (Chitonophora) ikonomovi nevadensis Alba‐Tercedor, 1983 is established.

Caenis rhenicola Malzacher 1976 is shown to be a new synonym of Caenis pusilla Navas 1913. A description of the diagnostic features is given as well as new records'from the Mediterranean region.

The male imagines of R. thomasi sp.n. and R. monserrati sp.n. are described and figured, based on fresh specimens from Spain. Differences between these and the related species are discussed.

The male of Hydraena (Haenydra) tatii sp.n. is described and illustrated. It is known from three localities in the Sierra Nevada, Granada (southern Spain). Ecological notes are provided.