The larval morphology of Arrenurus nobilis Neuman, 1880 and A. robustus Koenike, 1894 (Acari: Parasitengona: Arrenuridae)

The morphology of the larval stages of Arrenurus nobilis and A. robustus is described. Particular attention is given to characters that help to distinguish the two species, and to characters defining the subgenus Arrenurus s. str. The larva of A. robustus resembles the larvae of A. papillator and A. pustulator regarding the shape of dorsal plate, excretory pore plate, coxal plate median margins ratios, and the presence of the IIITa8 seta. The shape of the excretory pore plate in A. nobilis resembles the one in Arrenurus (Megaluracarus) mediorotundatus. The shape of dorsal plate and chelicerae is similar to the ones in the Megaluracarus-species A. globator and A. tubulator. The lack of the IIITa8 seta differs from other species of the subgenus Arrenurus s. str. In the pectinate Lp2 and Mh1 setae A. nobilis resembles representatives of the subgenus Arrenurus s. str. This demonstrates the necessity of verifying the taxonomic status of A. nobilis.     

Anatomy and ultrastructure of the salivary (prosomal) glands in unfed water mite larvae Piona carnea (C.L. Koch, 1836) (Acariformes: Pionidae)

Anatomy and ultrastructure of prosomal salivary glands in the unfed water mite larvae Piona carnea (C.L. Koch, 1836) were examined using serial semi-thin sections and transmission electron microscopy. Three pairs of alveolar salivary glands shown are termed lateral, ventro-lateral and medial in accordance with their spatial position. These glands belong to the podocephalic system and are situated on the common salivary duct from back to forth in the above mentioned sequence. The arrangement of the medial glands is unusual because they are situated one after another on the medial (axial) body line, therefore they are termed anterior and posterior medial glands. The secretory duct of the anterior medial gland mostly turns right, and the duct of the posterior gland turns left. The salivary glands are located in the body cavity partly inside the gnathosoma and in the idiosoma in front of the brain (synganglion). Each gland is represented by a single acinus (alveolus) and is composed of several cone shaped secretory cells arranged around the large central (intra-acinar) cavity with the secretory duct base. The cells of all glands are filled with secretory vesicles of different electron density. The remaining cell volume is occupied by elements of rough endoplasmic reticulum, and the membrane enveloping vesicles may have ribosomes on its external surface. Large nuclei provided with large nucleoli occupy the basal cell zones. The pronounced development of the prosomal salivary glands indicates their important role in extra-oral digestion of water mite larvae.     

中国湿螨属(蜱螨目,水螨群)一新纪录种长孔湿螨及短胸湿螨雄螨的首次描述

描述了采自四川省的湿螨属中国1新纪录种,长孔湿螨Hygrobates(Hygrobates) longiporus Thor,1898,首次描述了短胸湿螨H.(H.) bravisterus Jin,1997的雄螨,并给出了两个种的特征图.标本保存在贵州大学昆虫研究所.     

Loss of larval parasitism in parasitengonine mites

Larval Parasitengona are typically parasites, yet at least 29 species of water mites and one species of Trombidiidae forgo larval feeding and any association with a host. Species with non-feeding larvae are isolated cases within species groups or genera where the remaining species have parasitic larvae. Species without larval parasitism occur in at least 14 genera, eight families and four superfamilies of water mites; the loss of larval parasitism is presumably polyphyletic, having occurred at least 21 times. Lineages of water mites with non-feeding larvae frequently exist in parallel with almost identical populations or species that have parasitic larvae. Thus, there is tremendous potential for studies comparing the relative merits of the two life history strategies. Comparisons indicate that adults from lineages with non-parasitic larvae produce smaller numbers of larger eggs; the extra nutrition included in larger eggs permits the larvae to forgo feeding. Non-feeding larvae frequently have wider dorsal plates but reduced leg length, setal length and sclerotization when compared to parasitic larvae from sister lineages. The adults of lineages with non-feeding larvae are frequently smaller in comparison to adults of sister lineages with parasitic larvae. There is no apparent pattern in relation to habitat: lineages lacking larval parasitism occur in streams, temporary ponds and the littoral and planktonic regions of permanent lakes. © Rapid Science Ltd. 1998     

刺触螨属二新种记述(蜱螨亚纲,水螨群,刺触螨科)

记述了中国刺触螨属2新种:被绒刺触螨Sperchon lanigerus Guo et Jin,sp.nov.和透明刺触螨Sperchon perspicuus Zhanget Jin,sp.nov.,模式标本保存于贵州大学昆虫研究所。     

The morphology of the larval stages of three species (Arrenurus mediorotundatus Thor, 1898; Arrenurus conicus Piers 1894; and Arrenurus cylindratus Piers, 1896) of the Megaluracarus subgenus (Acari: Hydrachnidia: Arrenuridae)

The morphology of the larval stages of three species (Arrenurus mediorotundatus, Arrenurus conicus and Arrenurus cylindratus) belonging to the Megaluracarus subgenus is described. Particular attention is paid to the common characters of the three species in which they differ from the other species belonging to the other subgenera. These are: the shape of the excretory pore plate, the shape of the dorsal plate, the length of coxal plate II medial margin and the C1-CpI, C4-CpIII distances. Other characters differ between the three species also. These are: the shape of the dorsal plate, the shape of coxal plate III, the shape of excretory pore plate and the presence or absence of secondary setae of the IFe3 setae.     

A template for the future: digitizing and databasing a taxonomic illustration collection

This is the first iconographic taxonomic database intended as an everyday tool for the practising taxonomist, that allows access to the original drawings used to describe species. We demonstrate the system with water mites (Acari, Parasitengona, Hydrachnidia) but it may be used with any other plant or animal group. Query by genus or species leads to the original drawings and any additional images associated to that particular name. At present, the database includes images from more than 4,000 species (around 38,000 illustrations) and is easily expandable. Copyright does not allow the database to be used in an open WWW context, but it can be an extremely useful tool in private taxonomic applications.     

Organization of unusual idiosomal glands in a water mite, <Emphasis Type="Italic">Teutonia cometes</Emphasis> (Teutoniidae)

The unusual idiosomal glands of a water mite Teutonia cometes (Koch 1837) were examined by means of transmission and scanning electron microscopy as well as on semi-thin sections. One pair of these glands is situated ventrally in the body cavity of the idiosoma. They run posteriorly from the terminal opening (distal end) on epimeres IV and gradually dilate to their proximal blind end. The terminal opening of each gland is armed with the two fine hair-like mechanoreceptive sensilla (‘pre-anal external’ setae). The proximal part of the glands is formed of columnar secretory epithelium with a voluminous central lumen containing a large single ‘globule’ of electron-dense secretory material. The secretory gland cells contain large nuclei and intensively developed rough endoplasmic reticulum. Secretory granules of Golgi origin are scattered throughout the cell volume in small groups and are discharged from the cells into the lumen between the scarce apical microvilli. The distal part of the glands is formed of another cell type that is not secretory. These cells are composed of narrow strips of the cytoplasm leaving the large intracellular vacuoles. A short excretory cuticular duct formed by special excretory duct cells connects the glands with the external medium. At the base of the terminal opening a cuticular funnel strengthens the gland termination. At the apex of this funnel a valve prevents back-flow of the extruded secretion. These glands, as other dermal glands of water mites, are thought to play a protective role and react to external stimuli with the help of the hair-like sensilla.