Go to National Library of New Zealand Te Puna Mātauranga o Aotearoa
Volume 66, 1937
This text is also available in PDF
(389 KB) Opens in new window
– 225 –

Further Notes on the Genus Coelostomidia Cockerell

[Read before the Philosophical Institute of Canterbury, May 6, 1936; received by the Editor, May 20, 1936; issued separately, December, 1936.]

Since the publication of my last paper on the genus Coelostomidia (1) observations on this interesting genus have been continued, and facts have come to light that, I believe, are well worth recording. My study has been mostly confined to one species, C. assimile Mask., but at the same time no opportunity has been lost to gain as much knowledge as possible of the life-history of the other species.

Maskell (2) first reported C. assimile as being found in the Reefton district on Fagus sp. The paper referred to was read before the Wellington Philosophical Institute in 1889, and gave a description of the second instar only. In 1890 Maskell supplemented this with more information of the second instar, and added also that of the adult female and larva, giving as the host-plants Fagus Menziesii, Phyllocladus trichomanoides, and Fagus fusca. To these hosts I now add Laurelia novae-zealandiae. Morrison (3) in his work on the classification of the Margarodinae considered that “Certain of the various lots of material examined in connection with this study show some differences, when compared with the Maskell type material, that hint at specific distinctness,” and goes on to state some of the variations he had noticed. Many of these variations had long been known to me, but they were so slight and so erratic in their appearance in different lots of material, and so little is known of the life-history of any of the species of the genus, that many explanations, such, for instance, as age or sex, could have been given for the variation. Even now with the knowledge recently gained evidence is still insufficient to show that there is really a specific distinction. As stated in my previous paper on the above subject (1), there did not then appear sufficient reason for the separation of C. assimile under a distinct genus, and the discoveries recently made have confirmed that opinion; but further investigations will have to be made into all the species of the genus and the results compared with at least one Peruvian genus, which is apparently very closely related. There is no doubt that sufficient evidence has been gained to show that the generic characteristics as given by Morrison (3) for the genus Ultracoelostonia are quite inadequate.

We now come to deal with the latest discoveries, the first of which was made when I received from Ngatea some specimens of C. assimile on Laurelia. These to all appearance were typical specimens, and on examination were all found to be in the intermediate stage. On being prepared and mounted, most, though not all, were found to differ very much from the typical in that the legs were much larger than normal, and had it not been for the deeply chitinised abdomen I should have identified them as C. zealandica. A further request for more specimens resulted in a couple of tests of adult females, one of which I mounted. This proved to be an

– 226 –

almost typical example of the species, the only variation being in the larger abdominal spiracles and possibly in the fewer derm pores on the abdomen. Unfortunately, I was unable to obtain further specimens from this locality, and with a limited knowledge of the life-history of this species had to conclude that the difference found in the intermediate stage of this insect was due either to the age of the specimens or to sexual influence.

Recent collections made on Nothofagus Menziesii at Maruia have been sufficient to convince me that great variation is to be found in C. assimile, and may ultimately be sufficient for the erection of one or more varieties. There may be a difficulty in identifying the different stages of each distinct adult, but this may partly be overcome by studying the cast skins enclosed in the tests with the adult females. I have already been able to do this with the two varieties from Maruia, and I have also the larva of one. As regards the cast skins of the intermediate stage there are slight differences found that are not apparent in any of the other slides of this stage from Maruia, and I think that this is probably due to the age of the insects. It may be of interest to know that when an adult moults the skin of the intermediate stage splits down the back from between the antennae to a little above the chitinised abdomen. The chitinised abdominal portion remains in position covering the little aperture in the test, while the remainder of the old skin finally becomes tightly packed round it. As regards the larva there appears to be very little difference from the normal, the abdominal spiracles appear to be slightly larger than is usual, and the ventral cicatrices are arranged in a more acute triangle.

There is a great difference, however, in some of the adult females collected at Maruia. In these the mentum is present, well-developed, two-segmented, slightly chitinised, with a few setae at tip, and quite as large as that of the intermediate stage. The rostrum is poorly represented by a few chitinised fragments in their proper position; the rostral setae were absent. The legs are long and thick, tapering towards the claw, indistinctly segmented, the claw large, with two pairs of digitules. The thoracic spiracles were large with a cluster of pores at entrance; and the abdominal spiracles also have a cluster of pores at entrance. In the mouth-parts, the legs, and the abdominal spiracles these specimens differ from all others in my collection. The adult females of the other variety from Maruia are almost exactly similar to those of the same stage collected in other districts. If this difference had been noted in only a single specimen there would be some reason to believe that it was a freak of nature, but as it has occurred in four out of seven mounted specimens of this stage collected at Maruia, the only reasonable conclusion one can arrive at is that it is a distinct variety. This is further exemplified in the derm-pores of the second instar of those females retaining the mouth-parts; these have principally a quadrilocular centre, while the other variety from Maruia, and those collected from other parts of the country, all have derm-pores showing trilocular centres with an occasional quadrilocular.

– 227 –

Morrison (3) in his paper on the Margarodinae erected the genus Paracoelostoma to contain a single species found in Peru, in which the rostrum and mentum are retained in the adult females, and the legs are also fairly large and exactly similar to some of those specimens found at Maruia. The abdomen of the intermediate stage and larva of this species are deeply chitinised, similar to that of C. assimile. Judging from his written description and illustrations this species agrees well with some of the specimens collected at Maruia, the main difference being found in the larva of Paracoelostoma, in which the ventral cicatrices are arranged in two perpendicular rows. Apart from this and the more developed rostrum in the adult female, the difference is but slight, being principally in the derm-pores, which in Paracoelostoma are mostly bilocular.

It is well worth noting that some specimens of C. zealandica are also found to have a small rudimentary mentum, but they are by no means so well-developed as those found in assimile at Maruia. It is more than probable that when this genus has been thoroughly studied, the remaining species will be found to vary in a similar manner.

I must here point out a mistake that occurred in my paper on the Coelostomidia (1). In the table for identification it is stated that the adult female of pilosa had an antenna of ten joints. This should have read: Ten to eleven joints.

Below will be found a short description of the variation of two different stages of C. assimile taken from different parts of the country. In only two instances have I been able to allot the intermediate stages with their respective adults. The others must for the time being remain unknown, as no certainty can be attained unless the cast skin of the intermediate stage is mounted with the adult.

A Short Description of C. assimile Collected in Different Localities.

Adult Females.

Variety of Laurelia, Ngatea.

Antennae—Five joints.

Mouth-parts—Entirely absent.

Legs—Small, conical, not chitinised, with numerous small setae, claw small with single pair of digitules.

Spiracles—Thoracic: large, with group of pores at entrance. Abdominal: large, without pores.

Rectal tube—Simple, with lightly chitinised ring at opening.

Derm-pores—In about four broad bands on abdomen, elsewhere sparse.

Derm-setae—In about four broad bands on abdomen, elsewhere sparse.

– 228 –

Variety on Nothofagus Menziesii, Maruia, No. 1.

Antennae—Six joints.

Mouth-parts—Mentum present, two segmented, longer than broad, chitinised, rostrum limited to a few chitinised fragments.

Legs—Long, thick, tapering to claw, about four indistinct joints, claw large, with round base, and two pairs of digitules.

Spiracles—Thoracic: large, with group of pores at entrance. Abdominal: large, with group of pores at entrance.

Rectal tube—Simple, with chitinised ring at opening.

Derm-pores—In about four broad bands on abdomen, very numerous, sparse elsewhere.

Derm-setae—In about three broad bands on abdomen, sparse elsewhere.

Variety on Nothofagus Menziesii, Maruia, No. 2.

Antennae—Five joints.

Mouth-parts—Entirely absent.

Legs—Small, conical, not chitinised, claw short and thick, digitules in two pairs.

Spiracles—Thoracic: large, with group of pores at entrance. Abdominal: large, without grouped pores.

Rectal tube—Simple, with chitinous ring at entrance.

Derm-pores—Four broad bands on abdomen, but not so numerous as in previous variety, elsewhere sparse.

Derm-setae—About three broad bands on abdomen, sparse elsewhere.

Variety on Nothofagus fusca, Motueka.

Antennae—Four joints.

Mouth-parts—Entirely absent.

Legs—Small, conical, slightly chitinised, claw large, digitules in two pairs, distinct denticle.

Spiracles—Thoracic: large, with group of pores at entrance. Abdominal: large, without pores.

Rectal tube—Simple, with chitinised ring at opening.

Derm-pores—About four broad bands on abdomen, sparse elsewhere.

Derm-setae—About three broad bands on abdomen, sparse elsewhere.

Intermediate Stage.

Variety on Laurelia, Ngatea, No. 1.

Antennae—Six to seven joints.

Legs—Very large, thick, curved, with five distinct joints, claw very small, with single pair of digitules.

Spiracles: Thoracic: small, with few pores at entrance. Abdominal: very small, with single pore at side behind entrance.

Rectal tube—Short, otherwise normal.

Abdomen—Lightly chitinised.

Derm-pores—Not very plentiful, mostly with trilocular centres.

– 229 –

Variety on Nothofagus Menziesii, Maruia, cast skin, No. 1.

Antennae—Seven joints.

Legs—Small, conical, claw fairly large, with two pairs of digitules.

Spiracles—Thoracic: large, with ring of pores at entrance. Abdominal: large, with ring of pores behind entrance.

Rectal tube—Not observed.

Abdomen—Very deeply chitinised, almost black.

Derm-pores—Numerous on abdomen, sparse elsewhere, nearly all quadrilocular.

Variety on Nothofagus Menziesii, Maruia, cast skin, No. 2.

Antennae—Five joints.

Legs—Small, conical, claw small, with one pair of digitules.

Spiracles: Thoracic: large, with ring of pores at entrance. Abdominal: large, with one pore on each side behind entrance.

Rectal tube—Long, normal.

Abdomen—Lightly chitinised.

Derm-pores—Numerous on abdomen, sparse elsewhere, nearly all trilocular.

Variety on Nothofagus sp., Kowai Bush, Canterbury.

Antennae—Five joints.

Legs—Small, conical, slightly chitinised, claw small with two pairs of digitules.

Spiracles—Thoracic: large, with ring of pores at entrance.

Rectal tube—Long, normal.

Abdomen—Deeply chitinised.

Derm-pores—Numerous, nearly all trilocular. Abdominal: large, with ring of pores behind entrance.

Variety on Nothofagus fusca, Motueka.

Antennae—Four joints.

Legs—Small, conical, not chitinised, claw large, with two pairs of digitules.

Spiracles—Thoracic: large, with ring of pores at entrance. Abdominal: large, with ring of pores behind entrance.

Rectal tube—Long, normal.

Abdomen—Deeply chitinised.

Derm-pores—Very numerous, nearly all trilocular.

Literature Cited.

(1) Brittin, G., 1935. Notes on the Genus Coelostomidia, with Description of one Species and Table for Identification, Trans. Roy. Soc. N.Z., vol. 65, pt. 1, p. 63.

(2) Maskell, W. M., 1889. Further Notes on Coccididae, with Descriptions of New Species from Australia, Fiji, and New Zealand, Trans. N.Z. Inst., vol. xxii, p. 133.

(3) Morrison, H., 1928. A Classification of the Higher Groups and Genera of the Coccid Family Margarodidae, U.S. Depart. Agric., Tech. Bull. No. 52, pp. 86–117.