Lachnodius brimblecombei Beardsley, Gullan & Hardy

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 brimblecombei Beardsley, Gullan & Hardy sp. n. Figs 1a, 3

Diagnosis.

Gall of adult female covers portion of dorsum; adult female with marginal fringe of close-set setae, each longer than anal ring setae; one size class of dorsal macrotubular ducts.

Description.

Adult female (n = 10). Body outline circular to oval; length 2.6-7.3 mm (4.9 mm for holotype), greatest width 2.3-4.9 mm (3.8 mm for holotype). Eyes 43-58 μm wide, on margin. Antennae seven-segmented; length 980-1380 μm; with 4-5 hair-like setae on segment I, 9-11 hair-like seta on segment II, 6-8 hair-like seta on segment III, 2-3 hair-like seta on segment IV, zero or one hair-like + one fleshy seta on segment V, two hair-like setae + one fleshy seta on segment VI and six hair-like setae + three fleshy setae on segment VII. Frontal lobes 250-300 µm long, 65-165 µm wide. Tentorial box 375-510 μm long, 200-280 μm wide, with anterior extension of the dorsal arms. Labium two-segmented, 160-210 μm long, 170-215 μm wide. Spiracles 190-240 μm long, 140-215 μm wide across atrium. Legs increasing in size caudad, fore leg: trochanter + femur 710-1060 μm, tibia 590-900 µm, tarsus 225-320 μm; mid leg: trochanter + femur 770-1150 μm, tibia 610-900 µm, tarsus 240-325 μm; hind leg: trochanter + femur 810-1260 μm, tibia 650-1040 µm, tarsus 260-400 μm; claw 63-90 μm; fore coxa with 6-8 setae, mid and hind coxae each with 5-7 setae, trochanter with 6-8 setae, femur with 15−31 setae, tibia with 19-38 setae, tarsus with 10-16 setae; tarsal digitules 83-100 μm long, claw digitules 50-73 μm long; translucent pores on all segments of hind leg. Anal ring 80-108 μm wide, with 12-16 setae; ring setae 70-115 μm long. Pair of elongate caudal setae absent.

Dorsum. Derm membranous. Dorsal setae 8−10 μm long, each parallel-sided, with acute apex, scattered over dorsum. Macrotubular ducts with rim of dermal orifice 5 µm in diameter, duct shaft 8-10 µm long, 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 setae, each 70-118 µm long, ca. 200 setae in total on each side of body.

Venter. Larger than dorsum. Ventral setae 40-180 μm long; elongate setae medial of each coxa 150-225 μm long; longest setae on head 205-350 μm long. Macrotubular ducts similar to those on dorsum; in transverse band across each abdominal segment, scattered throughout submargin, medial of meso- and metacoxa. Quinquelocular pores 5 μm in diameter, found wherever setae occur, in transverse band across each segment, in a dense band along submargin, dense on posterior abdominal segments and around each spiracle.

Second-instar female (n = 9). Shape of slide-mounted specimen moderately elongate oval to broadly oval; length 1.9-3.0 mm, width 0.8-1.1 mm. Antennae six-segmented, short (230 µm total length), basally broad, becoming narrower toward apex, segment III ca. 60 µm wide. Legs short, broad, all segments present but tibiae and tarsi partially fused; tarsal claws incompletely developed. Anal ring ca. 30 µm wide, with ca. 10 setae, each of 25 µm maximum length. Dorsum with sparse, scattered setae, very small (mostly 4-5 µm long), acute or with blunt apices, and sparsely scattered, very small, tubular ducts ca. 2-3 µm in orifice diameter. Marginal fringe a moderately sparse series of 85-90 conical setae on each side of body, each seta ca. 35-50 µm long; antepenultimate seta of fringe on each side longer, ca. 80-90 µm long; fringe setae within a narrow marginal band of quinquelocular pores ca. 4-6 pores wide, extending around body; a small number of trilocular and quadrilocular pores scattered among quinquelocular pores. Venter with a few quinquelocular pores near each spiracle. Ventral setae flagellate, ranging from 10-65 μm long on thorax and abdomen, as long as 115 μm on head.

Second-instar male (n = 3). Shape of slide-mounted specimens moderately elongate-oval; length 1.2-1.5 mm. Antennae 7-segmented, ca. 280 µm long, slender, segment III 30-40 µm wide. Legs normal, slender, all segments present with tibiae 1.7-1.9 times length of tarsi; tarsal claws normally developed. Anal lobes narrowly separated by shallow anal cleft. Anal ring ca. 40 µm wide, with approximately 10 setae, 45 µm maximum length. Dorsum with derm finely spiculate. Dorsal setae sparse, scattered, short (ca. 4 µm long), acute, borne on papillae with narrow sclerotized rims. Dorsum with numerous (ca. 80) moderately large (ca. 8 µm rim and 6 µm orifice diameter) macrotubular ducts arranged in segmental rows. Marginal fringe of ca. 85 setae on each side, each seta moderately long (ca. 28-45 µm), conical with more or less filamentous apex; antepenultimate seta on each side much longer, to 105 µm; three most posterior setae on each side (including elongate antepenultimate) borne on a small, sclerotized anal lobe. Venter with a marginal line of quinquelocular pores just mesad of marginal fringe, around entire body, approximately as numerous as fringe setae; pores very sparsely scattered elsewhere on venter. Ventral tubular ducts absent. Ventral setae flagellate, ranging from 15-50 µm on thorax and abdomen, as long as ca. 125 µm on head.

Notes.

The slide-mounted adult female of L. brimblecombei is most similar to that of L. lectularius . Each has a marginal fringe of close-set setae, and the dorsum densely beset with macrotubular ducts of a single type, none of which have a seta touching the dermal orifice. In life the two are easy to distinguish. The adult female of L. brimblecombei induces a deep stem or bud gall with considerable swelling of the surrounding tissue that covers a portion of the female’s dorsum (Fig. 1a). If the gall occurs on the stem, it causes the stem to bend (Fig. 1a), often sharply. The adult female of L. lectularius also induces a gall on the stem or bud of the host, but the gall does not cover any portion of the female’s dorsum (Fig. 2a, b), and if on a stem does not make it crooked. Slide-mounted specimens of L. brimblecombei can be distinguished from those of L. lectularius by having (1) a dense marginal band of quinquelocular pores on the venter (absent in L. lectularius ) and (2) the marginal setae longer than the anal ring setae (marginal setae shorter than anal ring setae in L. lectularius ).

The habitat of the Victorian specimens of L. brimblecombei , which develop in galls formed on flower buds, is different from that of the type specimens from Queensland (with galls as in Fig. 2a). But we found no significant morphological differences among specimens from the different states, except for slightly smaller fringe setae and possibly fewer quinquelocular pores in the Victorian specimens. In case further study reveals that the Victoria specimens are different, we have restricted the type series to specimens collected by AR Brimblecombe in Queensland and three adult females from New South Wales, one of which is a DNA voucher.

At Wilson’s Promontory in Victoria, galling caused by L. brimblecombei on E. baxteri reduces bud survival and flowering ( Andersen 1989). Monitoring of tagged eucalypt shoots showed that, although less than 12% of buds were galled by L. brimblecombei (misidentified as Opisthoscelis sp.), the presence of galled buds often caused the abscission of nearby non-galled buds and galling on flowering stems often resulted in the loss of entire inflorescences, but these losses may be exacerbated by low water availability. On heavily galled shoots, the proportion of flowers producing mature fruit was correlated negatively with degree of galling, indicating that there was no compensatory increase in the success of the non-galled buds. Thus L. brimblecombei may decrease the fitness of its host, especially during periods of low rainfall.

A live adult female from Wild Cattle Creek State Forest in New South Wales was covered in white powdery wax and had a marginal fringe of white wax filaments ca. 0.2 mm long. Evidence of attack by parasitoid wasps was seen in several of the specimens studied. Two females from Redland Bay, Queensland, contained mandibles of parasitoid larvae, and the specimen from Mittagong, NSW also was parasitized.

We also examined one large (ca. 10 mm long) adult female that may be a developmentally abnormal specimen of L. brimblecombei or it might be a new species. It was collected from a stem pit on E. fasciculosa at Belair in South Australia (ANIC). It differs from typical adult females of L. brimblecombei in having reduced and distorted legs and antennae, many more dorsal fringe setae and in lacking the narrow marginal band of disc pores.

Etymology.

Pioneering Australian coccidologist AR Brimblecombe recognized this species and used the manuscript name ' Lachnodius geniculatus’ to refer to it in his dissertation [citation of this name here is NOT intended to be for nomenclatural purposes; the name is not valid]. This species is named in Brimblecombe’s honor. The species epithet is a noun in the genitive singular.

Material examined.

Holotype: Queensland: adult female, on slide: ex pit gall in young twig of Eucalyptus micrantha , Redland Bay, 2 Aug 1937, AR Brimblecombe, No. SC 147 (QM). Paratypes: Queensland: 15 second-instar females (on three slides, including two on same slide as holotype), five second-instar males (on two slides with second-instar females): same data as holotype (QDPC, QM) [The slide of another adult female from the type series could not be located at QDPC.]; two adult females: Eucalyptus sp., Glasshouse Mts., Queensland, 20 Dec 1935, AR Brimblecombe (QDPC). New South Wales: one adult female: ex deep pocket gall in twig of Eucalyptus sp., Mittagong, 24 Nov 1899, WW Froggatt, #305 (ASCU); one adult female: ex stem depression, Eucalyptus sp., west side of Mt Jerrabomberra, 35.35S, 149.23E, 2 May 1993, LG Cook (ANIC); one adult female: ex stem gall, Eucalyptus sp. sapling, Wild Cattle Creek State Forest, above Platypus Flat, 30.18S, 152.70E, 11 Oct 1996, PJG, Lach4 of LGC (ANIC). Additional material: Victoria: two adult females, four second-instar females: ex deep cavity galls in deformed flower buds, E. baxteri , Wilson’s Promontory, 8 Feb 1972, JWB (BPBM); one adult female, one second-instar female: ex deep galls in aborted flower buds, E. baxteri , Wilson’s Promontory, Squeaky Beach, 24 Feb 1972, A Yen (BPBM); two second-instar females, one second-instar male, three first-instar nymphs: ex bud galls, E. baxteri , Wilson’s Promontory, Tidal Overlook, 23 Sep 1982, AN Anderson (ANIC); eight adult females: same data as previous except 12 Nov 1982 (ANIC); one parasitized second-instar female (probably L. brimblecombei ), ex pit in swollen stem, E. baxteri , Grampians, Wartook Valley, Emu Holiday Park, 37.06S, 142.33E, 10 Jan 2011, PJG (ANIC).