Náttúrufræðingurinn - 1965, Side 57

NÁTT Ú RU FRÆÐIN G U RIN N
147
íslands. Hugsanlegt er, að Edwards hafi ranglega greint samband
kynjanna, því að eintökin í safni Petersons voru veidd ásamt karl-
dýrum tegundarinnar D. zeryni Edwards. Eru þau það fyrsta, sem
frétzt hefur af 1). zeryni á íslandi. I>á má og vera, að í fleiri en einni
norrænni Diarnesa séu kvendýr með stórum gulleitum stýrum (cerci).
Enda þótt hér sé gengið út frá, að Surtseyjareintakið sé það, sem
Edwards (1922) greindi sem I). ursus, verður staðfesting að bíða jsess,
að Diamesa-kerfið verði algerlega endurskoðað.
Surtseyjareintakið er geymt í Náttúrugripasafninu í Reykjavík.
Nákværn lýsing á því er í enska textanum hér á eftir.
The first insect collected on Surtsey, a new Icelandic island
by D. R. Uliver
Entomology Research Institute,
Canada Department of Agriculture, Ottawa, Ontario.
A submarine volcariic eruption occurred on 14 November, 1963, in the
Nortli Atlantic Ocean about 18 km. from Iceland. By mid-February, 1964,
the island, Surtsey, resulting l'rom this eruption ltad attained an area of
1 sq. ktn. and a height of 174 m. (F. Pálmadóttir 1964). On 15 May, 1964,
although lava was still flowing from the top, an insect was found on this
island. It probably was blown or flew to Surtsey from Iceland or the Vestmann
Islands. Although conditions were not favorable for establishing a population.
this illustrales how quickly colonization could start once volcanic activity
ceases.
The insect, a fcmale Diamesa ursus (Kieffer) (Diptera: Cliironomidae) was
recorded as Culex sp. (S. Friðriksson 1964). Dr. S. L. 'Fuxen, Universitetets
Zoologiske Museum, Copenhagen, Denmark, recognized that this determina-
tion was incorrect, since no Culicidae occur in lceland. He therefore arranged
to have the specimen sent to me for study.
The female of Diamesa ursus is characterized by the unusually large yellow-
ish cerci (Edwards 1922). The Surtsey specimen agrees in most ways with thc
description of Edwards, but differs in that the antennal segment 8 is well
separated from 7 and is as long as segmcnts 5—7 together, not 4—7. However,
the female antennal structure of Diamesa is variable, especially the relative
length of the terminal segment and the degree of fusion betwecn it and thc
penultimate segment. A number ol almost indentical specimens were present
in a recent collection from Iceland made by Dr. B. V. I’eterson, but in one
specimen the terminal segment is as long as the lengths of seginents 4—7
combined and partially fused to 7.