''Neuroterus numismalis'' is a
gall wasp
Gall wasps, also incorrectly called gallflies, are hymenopterans of the family Cynipidae in the wasp superfamily Cynipoidea. Their common name comes from the galls they induce on plants for larval development. About 1,300 species of this gener ...
that forms chemically induced leaf
galls on oak trees. It has both bisexual and agamic (
parthenogenetic
Parthenogenesis (; from the Greek grc, παρθένος, translit=parthénos, lit=virgin, label=none + grc, γένεσις, translit=génesis, lit=creation, label=none) is a natural form of asexual reproduction in which growth and developmen ...
) generations and forms two distinct galls on oak leaves, the silk button gall and blister gall. The galls can be very numerous with more than a thousand per leaf.
[Darlington, page 161]
Synonyms
''Neuroterus reaumuri'', ''N. vesicator'', ''Spathegaster vesicatrix'', ''Cynips numismalis'', and ''C. quercus-tiarae'' are previous binomials found in the literature.
Physical appearance
Galls
This silk button spangle gall has a cover of golden hairs that give the impression of silk thread. The 0.3 cm button-shaped galls have a pronounced concavity and sit tightly against the leaf lamina.
![Eikennapjesgal Neuroterus albipes forma laeviusculus-levelsadjust-mask](https://upload.wikimedia.org/wikipedia/commons/c/cf/Eikennapjesgal_Neuroterus_albipes_forma_laeviusculus-levelsadjust-mask.jpg)
Blister galls are about 0.3 cm in diameter and green or greyish in colour; well camouflaged with the leaf lamina. The gall has narrow ridges running downwards on all sides from a central papilla on the upper surface and sometimes on the lower surface as well.
[Stubbs, page 48] Both galls are both unilocular and unilarval.
Gall wasp
The female wasp of the bisexual generation is about 1.8–2.4 mm in length; largely brown in colour with clear wings and hairy legs. The male is also winged and slightly shorter than the female.
[''N. numismalis''](_blank)
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The agamic generation consists of only female wasps which measure approximately 2.5 mm in length. The pointed head is black, with pale brown eyes and long clear wings are present with dark brown veins and hairs.
Life cycle
Agamic generation
In late summer the agamic generation develops in the circular, golden brown, raised, and disc-shaped structure, known as a 'silk button spangle gall'. The gall increase in size even after they fall to the ground in autumn, this being achieved by cell enlargement rather than through further cell division. The gall wasp that causes the agamic generation was previously named as ''N. vesicator'' until the two generational status of the species was understood.
Bisexual generation
After having overwintered on the ground the females emerge from the silk button gall in early spring and the lay their parthenogenetic (unfertilised) eggs in expanding oak leaf buds, forming the so-called 'blister gall.' This second ''N. numismalis'' gall is located on the leaf blade as a structure which forms a convexity protruding from both the upper and lower lamina
The blister galls produce the males and females of the bisexual generation in mid-summer and the fertilised eggs result in the silk button gall generation.[Darlington, page 162]
Inquilines and parasites
The spangle gall generation in particular is affected by inquiline
In zoology, an inquiline (from Latin ''inquilinus'', "lodger" or "tenant") is an animal that lives commensally in the nest, burrow, or dwelling place of an animal of another species. For example, some organisms such as insects may live in the h ...
s and parasites. ''Synergus albipes'' is an inquiline on the blister gall, while common hyperparasite
A hyperparasite, also known as a metaparasite, is a parasite whose host, often an insect, is also a parasite, often specifically a parasitoid. Hyperparasites are found mainly among the wasp-waisted Apocrita within the Hymenoptera, and in two oth ...
s include ''Aulogymnus arsames'', ''Aprostocetus aethiops'', ''Eurytoma brunniventris'', ''Mesopolobus fasciiventris'', ''M. fuscipes'', ''M. sericeus'', ''M. tibialis'' and ''Torymus flavipes''.
Silk button galls also have ''Synergus albipes'' as an inquiline and examples of hyperparasites include; ''Aulogymnus gallarum'', ''Mesopolobus fasciventris'', ''M. tibialis'', ''Pediobius lysis'' and ''Torymus flavipes''.
See also
* Knopper gall
''Andricus quercuscalicis'' is a gall wasp species inducing knopper galls.
Knopper galls develop as a chemically induced distortion of growing acorns on pedunculate oak (''Quercus robur'' L.) trees, caused by gall wasps, which lay eggs in buds w ...
* Oak marble gall
''Andricus kollari'', also known as the marble gall wasp, is a parthenogenetic species of wasp which causes the formation of marble galls on oak trees. Synonyms for the species include ''Cynips kollari'', ''Andricus quercusgemmae'', ''A. minor'' ...
* ''Neuroterus quercusbaccarum
The common spangle gall on the underside of leaves and the currant gall on the male catkins or occasionally the leaves, develop as chemically induced distortions on pedunculate oak (''Quercus robur''), or sessile oak (''Quercus petraea'') trees, ...
''
* ''Neuroterus albipes
''Neuroterus albipes'' is a gall wasp that forms chemically induced leaf galls on oak trees which has both bisexual and agamic generations and therefore forms two distinct galls, the smooth spangle gall and Schenck's gall.Darlington, Page 162 ' ...
''
* ''Neuroterus anthracinus
''Neuroterus anthracinus'' is a widely distributed gall wasp that forms chemically induced leaf galls on oak trees. ''N. anthracinus'' has both sexual and agamic generations and in consequence forms two distinct galls, the oyster gall and April ...
''
References
Sources
* Darlington, Arnold (1975) ''The Pocket Encyclopaedia of Plant Galls in Colour.'' Pub. Blandford Press. Poole. .
* Stubbs, F. B. Edit. (1986) ''Provisional Keys to British Plant Galls''. Pub. Brit Plant Gall Soc. .
External links
*
{{Taxonbar, from=Q7002715
Cynipidae
Gall-inducing insects
Hymenoptera of Europe
Insects described in 1785
Oak galls