Invertebrates associated with the marine wood boring isopod,Limnoria tripunctata

Summary Untreated wood submerged for 4–6 months and infested with the marine wood boring isopod, Limnoria tripunctata Menzies, was analyzed for the associated invertebrate community. Associated with Limnoria were acoelous turbellarians, nematodes, the archiannelid Dinophilus sp., the tubicolous polychaete, Polydora sp., 4 harpacticoid copepods, 2 amphipods and the tanaid, Leptochelia savignyi. Limnoria ecto-commensals included ciliated and diatoms.Prior to dying Limnoria dug tomb-like side tunnels and then crawled inside to expire. All previous reports suggest that Limnoria leaves the wood to die.     

Male killing in three species of the tripunctata radiation of Drosophila (Diptera: Drosophilidae)

An excess of females in progenies is commonly referred to as sex-ratio (SR). In this report, we describe three new occurrences of SR in species of the tripunctata radiation, Drosophila neocardini , Drosophila ornatifrons and Drosophila paraguayensis. Repeated backcrosses with males from normal strains were used to maintain the SR strains in the laboratory, always with all-female broods. The egg–larva viability of the SR strains was approximately half that of a normal strain, and antibiotic treatment restored the production of males in SR strains. PCR screening with Spiroplasma -specific primers showed that only SR strains tested positive for Spiroplasma . The results showed that in the three species, SR was maternally inherited and involved early male-killing bacteria, most likely spiroplasmas. These new occurrences increase the number of cytoplasmic male killers described in Drosophila from 11 to 14. In this particular collection of flies, one quarter (3 out of 12) of the species from the tripunctata radiation of Drosophila was infected with a male killer, suggesting that this group may be a hot spot for the presence of male-killing organisms.     

The larva of Oecetis tripunctata (Fabricius, 1793) (Trichoptera,Leptoceridae)

Oecetis tripunctata is a widely distributed leptocerid in Europe, ranging from the Iberian and Apennine peninsulas and the Central and Western European highlands to the plains of Eastern Europe. The long, single-bladed mandibles are indicative for a predacious lifestyle. This paper describes the previously unknown larva of Oecetis tripunctata. Information on the morphology of the 5th larval instar is given, and the most important diagnostic features are illustrated. A synoptic key for the European species of Oecetis is also provided. In the context of existing identification keys the larva of Oecetis tripunctata keys together with Oecetis intima and Oecetis notata. Oecetis tripunctata is separated from the other two species by the fact that a double row of long setal fringes is lacking at the hind tibiae and that several long setae are present on the protrochantinus.     

On a New Collar Ciliate of a Gribble: Lobochona prorates n. sp. on Limnoria tripunctata

SYNOPSIS. Lobochona prorates n. sp., a collar cliate (CHONOTRICHIDA) ectocommensal on the pleopodal bristles of Limnoria tripunctata , is described. Lobochona prorates differs from the previously described chonotrichidan ectocommensal of the gribble, Lobochona limnoriae Dons on Limnoria lignorum (Rathke), in the outlines of the body and of the marginal lappets of the collar. The genus Lobochona Dons and the species Lobochona limnoriae Dons are redescribed.     

Interspecific and intraspecific variations in egg hatching for British populations of the stoneflies Siphonoperla torrentium and Chloroperia tripunctata (Plecoptera: Chloroperiidae)

SUMMARY 1. The objective was to compare variations in egg hatching between the two species (interspecific variations) and between populations of the same species (intraspecific variations). There were significant interspecific, but not intraspecific, differences in female size, adult life-span, egg production, hatching success, incubation periods and hatching periods.
2. The optimum temperature for hatching success within the range 3.8–22.1°C in the laboratory and the range over which at least 50% of the eggs hatched were lower for Chloroperia tripunctata (Scopoli) (8.5°C, 4.2–17.3°C) than for Siphonoperla torrentium (Pictet) (12.8°C, 6.1–19.4°C). Few eggs hatched at 22.r°C.
3. The relationship between incubation period (d days) and water temperature (T°C) was given by: d=1219/T^1.368 for S. torrentium , d=253/T^0.459 for C. tripunctata . Both equations successfully predicted incubation periods for eggs placed in a stream. The period over which eggs hatched was much longer for C. tripunctata than for S. torrentium at all temperatures.
4. The shorter incubation period (at r>5.6°C) and shorter hatching period for S. torrentium ensure that larvae of this species are already growing when eggs of C. tripunctata start to hatch, but the prolonged hatching period of the latter species ensures a long period of larval recruitment to the population. These differences in egg hatching may reduce competition between the two closely-related species.     

Dissymmetry of the origins of the roots of the spinal cord in the dog

The spinal cord in 25 non-inbred dogs has been studied macro-microscopically. The dissymmetry in the arrangement level in the right and left root bases on the dorsal surface of the spinal cord is much greater than on the ventral surface. The same as in the human being, the dissymmetry is the greatest in the thoracic part (as compared to other spinal parts). On the ventral surface of the spinal cord both along the anterior and posterior margin of the root bases, there is a right-sided dissymmetry (with cranial shift); on the dorsal surface it is present only at the roots along the posterior margin. The dissymmetry of the dog spinal cord is quantitatively estimated along its whole extension.