Lachnodius eucalypti (Maskell, 1892)

Hardy, Nate B., Beardsley Jr, John W. & Gullan, Penny J., 2019, A revision of Lachnodius Maskell (Hemiptera, Coccomorpha, Eriococcidae), ZooKeys 818, pp. 43-88 : 43

Lachnodius eucalypti (Maskell, 1892) Figs 1b, c, 4

Dactylopius eucalypti Maskell, 1892: 35; 1893: 233.

Lachnodius eucalypti : Maskell 1896: 400; Morrison and Morrison 1922: 44-48.

Diagnosis.

Loose marginal fringe with minute sagittate setae; microtubular ducts on venter of head; macrotubular ducts with distal attenuation.

Description.

Adult female (n = ca. 100). Body outline circular to oval; length 2.9-5.5 mm (3.5 mm for lectotype), greatest width 2.7-4.5 mm (3.0 mm for lectotype). Eyes 40-56 μm wide, on margin. Antennae seven-segmented; length 450-740 μm; with 2-3 hair-like setae on segment I, 4-10 hair-like seta on segment II, 2-6 hair-like seta on segment III, 4-7 hair-like seta on segment IV, 2-4 hair-like + one fleshy seta on segment V, 3-5 hair-like setae + one fleshy seta on segment VI and six hair-like setae + three fleshy setae on segment VII. Frontal lobes 210-300 µm long, 85-200 µm wide. Tentorial box 205-360 μm long, 175-265 μm wide, with anterior extension of the dorsal arms. Labium 90-125 μm long, 110-135 μm wide, one-segmented, proximal segment setae absent. Spiracles 110-175 μm long, 60-115 μm wide across atrium. Legs: trochanter + femur 400-660 μm, tibia 260-450 µm, tarsus 110-150 μm; claw 38-53 μm; fore coxa with six setae, mid and hind coxae each with five setae, trochanter with 4-8 setae, femur with 6-18 setae, tibia with 12-19 setae, tarsus with 4-9 setae; tarsal digitules 63-90 μm long, claw digitules 48-65 μm long; translucent pores on all segments of hind leg. Anal ring 78-115 μm wide, with 18-30 setae; ring setae 60-155 μm long. Pair of elongate caudal setae absent.

Dorsum. Derm membranous. Dorsal setae each parallel-sided, with acute apex, 5-7 μm long, scattered over dorsum. Macrotubular ducts with rim of dermal orifice 5 µm in diameter, duct shaft 13-20 µm long, distal portion (subtending vestibule) constricted, scattered over dorsum. Microtubular ducts ca. 5 μm long, with rim of dermal orifice ca. 2 μm wide, scattered over dorsum. Dorsum delimited by fringe of alternating minute sagittate setae, each 6-18 µm long, and slightly larger setae, 10-20 µm long, ca. 150 setae in total on each side of body.

Venter. Ventral setae 10-75 μm long; elongate setae medial of each coxa 40-115 μm long; longest setae on head 120-150 μm long. Macrotubular ducts similar to those on dorsum; in transverse band across each abdominal segment, scattered throughout submargin. Quinquelocular pores 5 μm in diameter, clustered around vulva and each spiracle, present wherever setae found. Microtubular ducts on head.

First-instar nymph (n = 14 from Bundoora, Victoria). This instar was redescribed and figured well by Morrison and Morrison (1922, figure 14) and only some additional information is provided here. Newly hatched individuals ca. 380-400 µm long; feeding first-instar nymphs removed from leaf galls 550-600 µm long, broadly oval in outline, with venter expanded, balloon-like, to fill gall cavity, dorsum flat. Slide-mounted specimens with medial to submedial dorsal derm bearing small sclerotic spots, mostly 1-2 µm in greatest dimension; marginal setae mostly falcate (incorrectly described as ‘flabellate’ by Morrison & Morrison) except posterior three pairs lanceolate but often with apex jagged or notched, each marginal seta 15-30 µm long. Pair of elongate caudal setae ca. 65 µm long.

Notes.

The adult female of L. eucalypti could be confused most easily with that of L. froggatti sp. n. Each induces pit galls on leaves and may be covered by waxy secretions. The adult female of L. eucalypti differs from that of L. froggatti by having (1) a marginal fringe of alternating sagittate and conical setae (marginal setae of L. froggatti hair-like to capitate); (2) eyes on margin (eyes on venter of L. froggatti ); (3) no dorsal macrotubular ducts with setae touching rim of dermal orifice (dorsum of L. froggatti having some macrotubular ducts with a seta touching dermal orifice); and (4) microtubular ducts on ventral surface of head (absent in L. froggatti ). Also, in life the secretions covering an adult female of L. froggatti are woolly, in contrast to the clumpy, powdery secretions that cover an adult female of L. eucalypti . Populations of L. eucalypti are known from all eight Australian states and territories. Specimens of L. eucalypti have been collected most commonly from E. camaldulensis , which is the most widely distributed species of Eucalyptus in Australia ( Brooker 2002), but they also have been taken from a number of additional species of Eucalyptus in three sections ( Adnataria , Exsertaria , and Maidenaria ) of the subgenus Symphyomyrtus . Two populations of adult females probably both from E. camaldulensis (Windjana Gorge in northern Western Australia and near Alice Springs in the Northern Territory) have the sagittate setae of the marginal fringe of more uniform length and larger (15-20 µm long) compared with populations from the eastern and southern states in which the sagittate setae vary in size from 6-18 (mostly <15) µm long on individual specimens. Due to this difference, we have excluded the females collected in the Northern Territory and Western Australia from the description above. Freshly collected specimens suitable for DNA sequencing might allow a decision on the species status of this morphological variation.

Life history data for L. eucalypti were obtained by JWB from a population that infested mature trees of E. camaldulensis on the campus of La Trobe University, Bundoora, Victoria, during the spring, summer, and fall of 1971-72. Beginning on 29 September 1971, adult females of L. eucalypti were collected while ovipositing on the bark of trunks and major branches of host trees. Oviposition was intermittent between then and mid-February 1972. Individual females appeared to complete oviposition within a short period of two or three days. The eggs were pink and laid in a single layer that formed a long, flat ribbon, 4-6 eggs wide, the top and sides of which were enclosed by a waxy secretion (Fig. 1c). Individual ovisacs were sometimes more than 5 cm long, straight or curved, and contained on the order of several hundred eggs (although no counts were made). A shrivelled, moribund female was often found at the end of an ovisac.

In the laboratory, eggs hatched 7-10 days after deposition. On host trees, the newly-eclosed first-instar nymphs migrated from the oviposition sites to the foliage, where they settled on the upper surfaces of young leaves. Feeding by each nymph resulted in a shallow pit gall on the leaf surface, which enclosed the nymph and grew along with it. The dorsal surface of settled first-instar and second-instar nymphs was nearly flat, smooth, and shiny, without evident waxy secretions. The ventral part of the nymph’s body filled the cavity of the pit gall, while the dorsal margin overlapped and sealed the edge of the gall cavity.

In second-instar females the legs are poorly developed and apparently non-functional. Male nymphs, which can be distinguished from females in the second instar by the presence of fully developed legs, developed in leaf galls similar to those of females. Second-instar males eventually abandoned their galls and migrated to the bark of trunks and branches of host trees where they formed ovoid cocoons in protected situations. In the laboratory, males formed cocoons under paper lining the bottom of the petri dishes in which they were held. Cocoons were formed of whitish filaments, which issued from the dorsal tubular ducts.

Females remained in their galls after molting to the third (adult) instar, and continued to feed for an undetermined period, until fully developed. They then abandoned their galls and migrated to the bark to oviposit. When and where mating took place was not determined. At La Trobe University, the population of L. eucalypti did not appear to reproduce synchronously. Although ovipositing females were observed only during the spring and summer months (September to February), individuals of all stages were found on the trees during late January.

Maskell (1892) described this species based on adult females, pupal and adult males, and first-instar nymphs, collected from a tree referred to as E. amygdalina . The following year, Maskell (1893) indicated that his type material of Dactylopius eucalypti was from South Australia, and that the specimens were collected under bark. It appears that Maskell received the type material from the South Australian collections accumulated by Frazer S Crawford of Adelaide, an economic entomologist with an interest in Coccoidea. However, the identification of the host tree as E. amygdalina is problematic if the insects came from South Australia, because this eucalypt is endemic to Tasmania. Specimens of a second collection, which Maskell received from WW Froggatt in Sydney, were in pit galls in the leaves of E. robusta . This difference in the site of collection on the host trees apparently gave Maskell the impression that the species developed both in leaf galls and under bark, and presumably he was unaware that adult females migrate from leaf galls to bark prior to oviposition.

The Maskell collection in the NZAC contains six slides of L. eucalypti , four of which we consider to be type material. The four slides with type specimens are labeled "Dactylopius eucalypti" with the word “Dactylopius” crossed out and “Lachnodius” written above it. These labels also have the locality as “Australia” and the date as “1886.” The slides bear (1) an adult female, (2) an adult male, (3) three first-instar nymphs, and (4) adult male parts (part of the thorax, two antennae, and two legs). The other two Maskell slides of this species in the NZAC contain (1) an adult female and (2) eight first-instar nymphs and bear later collection data (1893 and 1894) and therefore could not have been part of the material on which Maskell based his description. Beardsley had intended to designate the 1886 slide bearing the adult female as the lectotype of Dactylopius eucalypti Maskell, and labelled it as such in 1972 but this action was not published until now.

Note that there are also two slides of first-instar nymphs from the Maskell collection in the USNM, apparently from the type lot. Morrison and Morrison (1922: 44, 46) referred to one collection as “… a very small amount of material in position on the host, under Maskell No. 206" and listed the other slide as "Cotype. - Cat. No. 24762, U.S.N.M.". We examined both slides and list them below as paralectotypes.

Material examined.

Lectotype (here designated): adult female: on slide labelled: "Lachnodius / Dactylopius / eucalypti / adult female / Australia / 1886 W.M.M." (ANIC). Paralectotypes: one adult male (one slide), antenna and feet of adult male (one slide), three first-instar nymphs (one slide, labelled “Larvae”), same data as lectotype (NZAC); 12 first-instar nymphs: on slide labelled: "Lachnodius / eucalypti (Mask.) / Australia / Mask. Coll. N. 82 / Type" and envelope also with "Cotype Cat. No. 24962 / U. S. National Museum" (USNM); two first-instar nymphs: on slide labelled: "Lachnodius / eucalypti (Mask.) / Australia / Mask. Coll. 206 (USNM). Additional material: Unspecified locality in Australia: one adult female: same label data as lectotype except “1893” and "not type, described 1892 / L. L. Deitz 1978" [JWB erroneously added a paralectotype label] (NZAC); eight first-instar nymphs: same label data as lectotype except “1894” and "not type, described 1892" (NZAC); one adult female: ex Eucalyptus camaldulensis , quarantine intercept in Cambridge, UK, 1 Nov 1993, Newman, 93-1216 (ANIC). Australian Capital Territory: three adult females, 14 first-instar nymphs on three slides: ex trunk, E. mannifera , Charnwood (suburb), Canberra, 18 Nov 2015, PJG (ANIC); one adult female (parasitized), 65 first-instar nymphs on eight slides: ex pit gall on leaf, E. bridgesiana , Tidbinbilla Nature Reserve, 35.48S, 148.89E, 1 Mar 1992, PJG (ANIC). New South Wales: 15 adult females: ex pits in leaves, E. blakelyi , 6.5 km SE of Forbes, 28 Nov 1984, PJG (ANIC); one adult female (parasitized): under bark, E. viminalis , Bago State Forest, 10 km ESE of Batlow, 14 Jan 1979, PJG (ANIC); three adult females: ex foliage, Eucalyptus sp. (ironbark), nr Coonabarabran, Warrumbungle Nat. Park, Camp Pincham, 22 Nov 1985, CAM Reid (ANIC); one adult female: ex pit gall on leaf, E. saligna , S. Brooman, “Strathclyde” (property), bank of Clyde River, 35.52S, 150.22E, 10 Jan 1996, PJG (ANIC); one adult female: Dubbo, no date, Froggatt #1049 [JWB must have misread the Froggatt number as this collection matches #1079 for L. eucalypti : "WWF 20.11.1921 / Dubbo / Eucalyptus"] (ASCU); partial specimens of adult and second-instar females: ex pit galls, E. botryoides leaves, Kurnell, 26 Aug 1915, WW Froggatt, #621 (ASCU); one adult female: ex leaf pit,? E. tereticornis or E. seeana , South West Rocks, 30.90S, 153.02E, 30 Dec 2009, LG Cook, LGC01374 (ANIC); one adult female: in leaf pit gall, E. tereticornis , Wagga Wagga, 6 Nov 1899, WW Froggatt, # 297 (ASCU). Northern Territory: three adult females: Eucalyptus sp., N of Alice Springs, near Todd River, 19 Nov 1978, M Kotzman (ANIC). Queensland: six adult females: ex E. propinqua , Imbil, Oct 1936, AR Brimblecombe, No. D2264-6 (QDPC); three adult females, three second-instar males, five second-instar females: ex foliage, Eucalyptus sp., N side of Tamborine Mt, nr Sandy Creek, 26 Sep 1989, PJG (ANIC). South Australia: 15 adult females, two adult males, many first-instar nymphs, 14 second-instar males, six pupal males: E. camaldulensis , Adelaide, Glen Osmond, Waite Agric. Res. Instit., Dec 1952, HM Brookes, HMB Specimen Index No. 77/54 (ANIC); five adult females, one second-instar female: ex pits in leaves, E. camaldulensis , Glen Osmond, 27 Jul 1965, HMB, HMB Specimen Index No. 21/65 (ANIC); six adult females: on E. camaldulensis , 1 mile [1.6 km] N of Greenock, 19 Dec 1960, HM Brookes, HMB Specimen Index No. 109/60 (ANIC); 28 adult females: on bark of E.? camaldulensis , Hazelwood Park, 14 Nov 1966, RS Bungey, HMB Specimen Index No. 46/66 (ANIC); four adult females: ex pits in leaves of E. camaldulensis , Mt Crawford Forest Reserve, Jan 1982, HM Brookes, HMB Specimen Index No. 1/82 (ANIC); two adult females, four second-instar females: E. microtheca , nr Murnpeowie (homestead), 16 Aug 1968, FD Morgan (ANIC); one adult female: under bark, E. camaldulensis , nr Mt Barker township, 15 Dec 1985, CAM Reid (ANIC); one adult female, six adult males: under bark, E. camaldulensis , Sampson Flat, 7 Sep 1965, DC Purdie (ANIC). Tasmania: two adult females: E. globulus , Hobart, Sandy Bay, 21 Aug 1965, HMB (ANIC). Victoria: one adult female, six second-instar females, one second-instar male, six first-instar nymphs: ex pit galls on young leaves, E. camaldulensis , Bundoora, La Trobe University, 24 Jan 1972, JWB (BPBM); one adult female (parasitized mummy): ex pit gall on twig, same data as previous except 5 Jan 1971 JWB (BPBM); two adult females, eight first-instar nymphs: on bark, same data as previous except 29 Sep 1971, V-87 (BPBM except one slide with three nymphs in ANIC); 16 adult females: same data as previous except 10 Dec 1971, V-243 (BPBM); one adult female, two adult males: same data as previous except Oct 1971 (BPBM); three adult females, four second-instar males: on bark, E. goniocalyx , Melbourne, Lower Plenty, 11 Sep 1971 or 23 Sep 1971, JWB (BPBM); one adult female: on stem, E. camaldulensis , W of Benalla, 36.48S, 145.95E, 26 Nov 2006, PJG, NH150 (ANIC); five adult females, two second-instar females: on E. nitens , Errinundra Plateau, Orbost Forestry District, 21 Oct 1974, FG Neumann and GC Marks, HMB Specimen Index No. 14/74 (ANIC). Western Australia: 21 adult females, one second-instar female with pharate adult: ex gall, E. camaldulensis , Windjana Gorge Nat. Park, bank of Lennard River, 17.42S, 124.95E, 29 Apr 1992, PJG (ANIC except eight slides in WAM).