FNZ 21 - Margarodidae (Insecta: Hemiptera) - Introduction
Morales, CF 1991. Margarodidae (Insecta: Hemiptera). Fauna of New Zealand 21, 124 pages.
( ISSN 0111-5383 (print), ; no. 21. ISBN 0-477-02605-9 (print), ). Published 27 May 1991
There are eleven families of Coccoidea in New Zealand. The earliest work on this group was done by W.M. Maskell, who between 1879 and 1898 described over 300 new species of Homoptera from around the world, mostly scale insects from New Zealand. In their catalogue of Maskell's Homoptera, Deitz and Tocker (1980) listed the localities of the Maskell type specimens and gave details of his species-group names as well as including biographical details. Maskell's interest in the then new science of microscopy meant that he was well ahead of his contemporaries in describing species from slide mounts of specimens. Although they were not stained and had other deficiencies in mounting techniques (Ferris 1957), many of them can still be used today. Fortunately Maskell also preserved dry material, but it must be remembered by coccidologists who use this unmounted material that he was less than methodical about keeping specimens collected on separate days or from different localities in different boxes. However, Maskell was before his time in recognising that immature and male stages were also important to the taxonomy of the coccoids.
Since Maskell, the few taxonomic treatments of the New Zealand scale insect fauna include Hoy's (1962) revision of the Eriococcidae, Beardsley's (1964) paper on the Phenacoleachiidae, Green's (1929) comments on the Ortheziidae, Williams and De Boer's (1973) contribution on the Pseudococcidae, Emms's (1985) thesis on the Leucaspidinae, Brittin's (1935) paper on Margarodidae, Dumbleton's (1967) paper on Ultracoelostoma , De Boer and Valentine's (1977) taxonomic treatment of some diaspidid species, Lambin and Kosztarab's (1976) paper on Solenophora , and most recently Cox's (1987) extensive revision of the Pseudococcidae. Other systematic work on New Zealand coccoids has often been included in treatments of world genera, such as Morrison's (1928) revision of the Margarodidae, which included the then known fauna from New Zealand, Morrison and Morrison's (1922, 1923, 1927) redescriptions of coccoid and asterolecanoid species described by Maskell, and Russell's (1941) revision of the Asterolecaniidae.
A checklist (Wise 1977) of some of the Hexapoda of New Zealand included the Coccoidea, and a summary of the literature pertaining to the New Zealand members of this superfamily was given by Deitz (1979).
Apart from the introduced monophlebine species Icerya purchasi Maskell and I. seychellarum (Westwood) (the latter recorded as occurring in New Zealand, but so far only intercepted in quarantine), all species of Margarodidae found in New Zealand are test-formers belonging to the subfamily Coelostomidiinae.
Native margarodids are frequently encountered on a variety of trees, especially Nothofagus and Podocarpaceae. Adult females, which are wingless and look like large, pink mealybugs, may be found crawling on the forest floor or on the bark of trees during the summer months. The winged males are large, have dark red bodies, and are often caught in Malaise traps. More obvious, however, are the festoons of white cocoons of the male pupae on Leptospermum and Kunzea (Coelostomidia wairoensis ) and Nothofagus spp. (Ultracoelostoma assimile and U. brittini ). The waxy white tests of the second and third instars of several species are to be found throughout the year on or under bark, in amongst the moss layer on trees, or in the axils of branches and twigs of a variety of trees. Large amounts of sooty mould on the trunks and branches of Kunzea ericoides can indicate the presence of immature stages of C. wairoensis , just as a characteristic covering of sooty mould on the trunks of beech trees (Nothofagus ) is caused by secretion of honeydew by the immature stages of U. brittini .
In the New Zealand fauna, the females of Ultracoelostoma, Coelostomidia , and Platycoelostoma have four stages. Males have not been found in Platycoelostoma , but in the other two genera there are five male stages. The first instars have well developed legs and antennae, but the second- and third-instar females and the second-instar males occur inside a test and have reduced legs and antennae. However, the numbers of setae, spines, pores, and hairs increase after each moult, and in Ultracoelostoma the anal end becomes more sclerotised with the advancing age of each immature test-inhabiting instar.
The texture of the test varies from thick and resinous in Ultracoelostoma spp. and Coelostomidia zealandica to thin and powdery in C. pilosa , and elastic and papery in Platycoelostoma . The adult female of Ultracoelostoma species remains inside the test with reduced legs, mouthparts, and antennae, whereas the adult females of Coelostomidia and Platycoelostoma emerge from the test of the previous stage with well developed legs and antennae, but without functional mouthparts. The prepupal or third- instar males of Coelostomidia and Ultracoelostoma are superficially similar to adult females of Coelostomidia spp., but are smaller and have fewer antennal segments. On slide-mounted specimens there are two pairs of outpushings of the derm near the second pair of legs which later develop into the wing and hamulohaltere buds of the pupa. Adult males are usually fully winged.
Except for Ultracoelostoma brittini, which is important for the honey industry, the endemic species of New Zealand Margarodidae are of no economic importance. Since the 1960s U. brittini has been of interest to New Zealand beekeepers because the honeydew that it secretes is harvested by bees to make 'forest honey'. This honeydew also is an important component in the 'ecology of southern beech forests (Moller and Tilley 1987).
Earlier literature on the New Zealand Margarodidae is patchy, comprising Maskell's descriptions, Morrison and Morrison's (1922, 1923) redescriptions of the Maskell type-species, and Morrison's (1927, 1928) broader work dealing with Margarodidae, plus papers by Myers (1922), Green (1929), Brittin (1935, 1936), and Dumbleton (1967).
The first margarodid to be described from New Zealand was Icerya purchasi (Maskell 1879). Fernald's world catalogue of Coccidae (1903) listed Icerya seychellarum as occurring in New Zealand on the basis of a paper by Maskell (1897) in which he identified some coccoids sent to him by Koebele from China and Formosa. From 1881 to the 1920s there was a flood of literature relating to I. purchasi as a citrus pest and the search for and discovery in Australia of its biological control agent Rodolia cardinalis Mulsant.
An endemic New Zealand margarodid was described for the first time when Maskell (1880) erected the genus Coelostoma for the single species zealandica . The name Coelostomidia was proposed by Cockerell (1900), as Maskell's proposed generic name was preoccupied. Morrison and Morrison (1922) redescribed C. zealandica , and provided a diagnosis of genus Coelostomidia . In a later detailed revision of the Margarodidae, Morrison (1928) listed two more species in this genus, pilosa Maskell (1891) and wairoensis Maskell (1884). Cockerell (1902) and Fernald (1903) had earlier listed these three species, Fernald adding host records. Another species, C. montana , was added to Coelostomidia by Green (1929). Detailed descriptions of the immature stages of these four species and notes on their life history were given by Brittin (1935), but no keys or detailed diagrams were included.
The genus Ultracoelostoma was first described by Maskell (1890) from "Fagus" in the Reefton district of the South Island, as Coelostorna assimile . Cockerell (1902) established the subgenus Ultracoelostoma on the basis of the absence of legs and reduction of antennae in the adult female, and this was supported by Morrison and Morrison (1922). Brittin (1935) considered that U. assirnile should be retained in Coelostomidia because of the presence of leg rudiments in the adult female, the great similarity between the intermediate stages and adult males of Coelostomidia and Ultracoelostoma , and because the tests of U. assimile and C. zealandica are almost indistinguishable. The great variation in the degree of atrophy of legs and mouthparts in different populations of U. assimile confirmed Brittin's (1935) opinion that the criteria of presence or absence of legs used by Cockerell and Morrison to establish a separate genus was insubstantial, but that there were probably distinct 'varieties' within this genus. Dumbleton (1967) suggested that these varieties may indicate the presence ot one or more species on Nothofagus , and he recorded for the first time a species of Ultracoelostoma on Dracophyllum . The only differences he could find to separate this species from the populations on Nothofagus were in the length of the tarsal claw and, in life, the smaller and more elongate tests. A study of the morphology of U. assimile supported Brittin's assertions (Oliver 1975).
There is undoubtedly much variation in the degree of atrophy of legs, mouthparts, and antennae as well as in the numbers and distribution of pores and setae on the dermal vestiture in Ultracoelostoma and Coelostomidia but on the basis of the characters exhibited in the anal region of these insects, as well as other characters, it is my opinion that these two genera should be maintained.
The genus Platycoelostoma was established by Morrson and Morrison (1923) for one species, compressa , first described as Coelostoma compressum by Maskell (1892).
A major purpose of this work is to redescribe the species known from New Zealand, including their immature and male stages, and to provide life history information for two representative species in different genera.