Population biology of the crustose red alga Lithophyllum incrustans Phil. Three populations on the east coast of Britain

The distribution of the crustose red alga Lithophyllum incrustans in the British Isles is described. Three populations are analysed demographically, two having age class distributions corresponding to a type III survivorship curve characteristic of populations in which the greatest mortality occurs in the youngest age classes. The more southern of these two populations has a longer generation time (14.2 years) than the more northern (8.5 years). The third and most southern population has an age class distribution dominated by the 6- and 7-year-old categories. There were few sexual thalli (around 3^o,) but they appeared to put more effort into reproduction than the asexual thalli.     

The role of chemoreception in sex recognition by male crickets: Acheta domesticus and Teleogryllus oceanicus

ABSTRACT. Contact chemoreception is important in female recognition by Teleogryllus oceanicus (Le Guillou) males. Antennal contact of female conspecifics, body regions, detached antennae and conditioned substrate elicited mostly courtship responses including courtship songs. Aggressive acts were produced only in response to male conspecifics. Male body regions, detached antennae and conditioned substrate elicited very few courtship or aggressive acts and no songs. This suggests that one or several communication modes, in addition to chemical communication, are necessary to elicit aggressive responses. Acheta domesticus (L.) males cannot rely upon chemical cues for recognition of either sex. Responses to conspecifics suggest that A. domesticus males produce aggressive acts immediately after antennal contact with either sex. Aggressive response to males usually persists, but response to females often switches to courtship. Responses to body regions, detached antennae, and conditioned substrate were few, with courtship and aggressive responses elicited by both male- and female-generated stimuli. The importance of contact chemoreception in cricket communication is suggested by (1) failure of hexane-washed antennae to elicit aggressive or courtship acts, and (2) males spending more time in contact with body regions and conditioned substrates than with corresponding controls. Lack of response to male or female odour-laden air suggests that chemical signals are used by males only if directly contacted. Chemical and other signals supplement the obvious use of acoustic signals for intra- and intersexual communication in these crickets. The importance of multimodal communication in sex recognition is discussed.     

Fruit flies of the subtribe Gastrozonina of Indonesia,New Guinea and the Bismarck and Solomon Islands (Diptera,Tephritidae, Trypetinae,Acanthonevrini)*

Thirty one genera [including Homoiothemara gen.n., Polyaroidea gen.n., Proepacrocerus gen.n. and 1 unnamed new(?) genus], 3 subgenera, 87 species [including 9 new species: Acrotaeniostola interrupta, Carpophthorella bivittata, Enicoptera gressitti, Homoiothemara eurycephala, Polyaroidea distincta, P. opposita, P. univittata, Proepacrocerus pallidoviridus and Xanthorrachis sabahensis and 6 unnamed new(?) species] and 1 subspecies are keyed and described or, if recently described elsewhere, only listed and additional data recorded. The following are new synonyms: Trypeta retorta Walker, Carpophthorella magnifica Hendel, Gastrozona bifasciata de Meijere and Gastrozona alboscutellata Enderlein =Carpophthorella nigrifascia Walker; Icteroptera van der Wulp =Sophira Walker; Sophira disjuncta Hardy =Sophira (Kambangania)ypsilon (Rondani); Curvinervis walkeri Hardy and Strumeta concisa Walker =Stymbara vagaria Walker; Carpophthorella scutellomaculata Hering =Xanthorrachis annandalei Bezzi. Proanoplomus cinereofasciatus (de Meijere) is a new combination and Spilocosmia kotoshoensis (Shiraki) is given new status.     

Feeding ecology and phylogenetic structure of a complex neotropical termite assemblage,revealed by nitrogen stable isotope ratios

1. In the current ecological classification of termites, four feeding groups (I–IV) are recognised, corresponding to a gradient of decomposition from sound wood to highly mineralised organic matter in the soil. 2. Nitrogen stable isotopes (hereafter δ¹⁵N) were used to place termites from French Guiana rainforests along a wood‐soil decomposition gradient, to test (i) whether feeding group assignation based on morphological characters was accurate and actually represented diet specialisation thresholds, and (ii) to what extent the dietary specialization of species is explained by phylogeny (phylogenetic autocorrelation). 3. δ¹⁵N values vary over a range of 13‰, suggesting that diet diversification contributes to the high species diversity in French Guiana. δ¹⁵N values span a similar interval in all Termitidae subfamilies. Ranges of different subfamilies broadly overlap, although each of them diversified preferentially on one side of the wood‐soil decomposition gradient. Congeneric species share similar feeding habits, whereas distant species tend to feed on distinct substrates. 4. Feeding groups did not completely match stable isotope data: there was no discontinuity between Groups III and IV, and no correlation between anatomical criteria used to distinguish these groups and δ¹⁵N values. Nor was there any consistent difference in δ¹⁵N values between wood feeders of the families Rhinotermitidae (Group I) and Termitidae (Group II). We also suggest that species feeding outside the wood‐soil gradient should be distinguished for their peculiar feeding requirements.