New and rare British spiders

Summary

The following species new to Britain are described: Family LINYPHIIDAE Subfamily ERIGONINAE Erigone psychrophila Thorell (male only) Typhocrestus simoni Lessert (male only) Rhaebothorax paetulus (O. P.-C.) (both sexes) Subfamily LINYPHIINAE Centromerus parkeri sp. nov. (male only)

The new county records add 13 species to the Scottish list and eight species to that of Wales.

Species new to Scotland:

• Tibellus maritimus (Menge)

• Pirata uliginosus (Thor.)

• Theridion melanurum Hahn

• Wideria nodosa (O. P.-C.)

• Cornicularia kochi (O. P.-C.)

• Erigone capra Sim.

• Erigone psychrophila Thor.

• Rhaebothorax paetulus (O. P.-C.)

• Ostearius melanopygius (O. P.-C.)

• Porrhomma convexum (Westr.)

• Centromerus parkeri Sp. n.

• Bathyphantes parvulus (Westr.)

• Allomengea warburtoni (O. P.-C.)

Species new to Wales:

• Coelotes terrestris (Wid.)

• Wideria nodosa (O. P.-C.)

• Lophocarenum stramineum (Menge)

• Mecopisthes silus (O. P.-C.)

• Scotargus inerrans (O. P.-C.)

• Typhocrestus simoni Lessert

• Bathyphantes parvulus (Westr.)

• Taranucnus setosus (O. P.-C.)

     

Undescribed anatomical features of the gut of the house cricket,Acheta domesticus L. (Insecta,Orthoptera)

Summary

The following new anatomical features of the gut of Acheta domesticus are described and discussed:

• 1.A thin-walled dorsal evagination of the oesophagus, which may serve to circulate digestive fluid in the crop.

• 2.Lateral invaginations of the wall of the posterior oesophagus and anterior crop, separated from the circular muscle layer and allowing considerable enlargement of the foregut during feeding.

• 3.Strands of muscle and connective tissue linking the caeca and crop to the thoracic cuticle, innervated in part from the prothoracic ganglion, which may serve to register the extent of gut filling.

• 4.Evidence from the arrangement of the gut tracheae and nerves of rotation of parts of the gut from their original ancestral position, the gizzard and caeca being rotated through 90° and the crop through 180°. It is suggested that these rotations have been necessary to accommodate the gut components to changes in the shape and proportions of the body during the evolution of the cricket lineage.