Lachnodius melliodorae 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 melliodorae Beardsley, Gullan & Hardy sp. n. Fig. 9

Diagnosis.

Dorsum with numerous urn-shaped sclerotic invaginations; marginal fringe of curved setae; some dorsal macrotubular ducts with seta touching rim; anal ring invaginated.

Description.

Adult female (n = 15). Body outline circular to ovate; length 1.96-5.74 mm (4.02 mm for holotype), greatest width 1.53-3.90 mm (3.64 mm for holotype). Eyes dorsal, 38-45 μm wide. Antennae seven-segmented; length 680-882 μm; with 4-11 hair-like setae on segment I, 6-9 hair-like setae on segment II, 8-11 hair-like setae on segment III, 7-8 hair-like seta on segment IV, 3-5 hair-like setae + one fleshy seta on segment V, 5-6 hair-like setae + one fleshy seta on segment VI and six hair-like setae + three fleshy setae on segment V. Tentorial box with anterior extension of the dorsal arms, 350-475 μm long, 135-165 μm wide. Labium 135-165 μm long, 165-200 μm wide. Spiracles 140-225 μm long, 80-135 μm wide across atrium. Legs increasing in size caudad; fore legs: trochanter + femur 505-690 μm, tibia 410-560 µm, tarsus 183-250 μm; mid legs: trochanter + femur 548-750 μm, tibia 410-570 μm, tarsus 195-265 μm; hind legs: trochanter + femur 540-790 μm, tibia 490-590 µm, tarsus 200-263 μm; claw 45-63 μm; fore coxa with six setae, mid and hind coxae each with five setae, trochanter with 8-15 setae, femur with 20-37 setae, tibia with 28-50 setae, tarsus with 11-21 setae; tarsal digitules 73-93 μm long, claw digitules 45-68 μm long; translucent pores on all segments of hind leg, ca. 150 pores on dorsal surface and ca. 90 pores on ventral surface. Anal ring invaginated, cuticle surrounding ring sclerotic, 58-108 μm wide, with 10-15 setae; ring setae 45−108 μm long. Pair of elongate caudal setae usually absent, present in one specimen, ca. 28 μm long.

Dorsum. Derm beset with sclerotic spicules (i.e., well-developed microtrichia), in addition to sclerotic urns, each 4-6 μm wide. Dorsal setae lanceolate, 5-6 μm long, scattered over dorsum. Macrotubular ducts 15-20 μm long, with rim of dermal orifice 3-7 μm wide, ducts diminishing in size cephalad, many ducts with one seta affixed to rim of dermal orifice. Microtubular ducts ca. 5 μm long, with rim of dermal orifice ca. 2 μm wide, scattered over dorsum. Dorsum delimited by fringe of ca. 225 setae on each side of body; each seta slender and recurved, 15-23 μm long; marginal fringe interrupted by U-shaped sclerite between thorax and abdomen.

Venter. Ventral setae 20-50 μm long; elongate setae medial of each coxa decreasing in size caudad: 125-165 μm long near fore coxa, 50-95 μm long near hind coxa; longest setae on head 153-200 μm long. Macrotubular ducts each ca. 15 μm long, with rim of dermal orifice ca. 6 μm wide, found along margin and in a transverse row across each abdominal segment. Quinquelocular pores of two distinct size-classes: (i) larger pores ca. 5.5 μm in diameter, found on posterior abdominal segments; and (ii) smaller pores ca. 4 μm in diameter, near spiracles and along margin.

Notes. Adult females of L. melliodorae are most similar those of L. parathrix and L. maculosus . These three species share (i) a marginal fringe composed of close-set setae interrupted between the thorax and abdomen; (ii) two distinct size classes of quinquelocular pores on the venter; and (iii) several dorsal macrotubular ducts with a seta affixed to the dermal orifice. Adult females of L. melliodorae can be distinguished from those of L. parathrix and L. maculosus by having (i) recurved marginal setae (marginal setae straight in L. parathrix and L. maculosus ) and (ii) an U-shaped sclerite between the thorax and abdomen on the margin on each side of the body (sclerite absent in L. parathrix and L. maculosus ).

Young adult females collected near Benalla, Victoria, by PJG in 1996 and 1997 were pale yellow in life with dorsomedial longitudinal stripe of red-wine color; the anterior spiracular furrow was visible as a pale line on each side of the body. The dorsum was naked (no secretion), but each seta in the marginal fringe was covered in a glassy secretion. The second-instar female had a salmon-colored dorsum.

The type series is restricted to specimens collected at Lower Plenty in Victoria, where JWB made several collections of all instars of this species.

First-instar nymph (n = 8). Body outline ovate; length 280-360 μm, greatest width 215-290 μm. Eyes 12-15 µm wide. Antennae six-segmented but appearing 5-segmented due to partial fusion of segments III and IV; length 65-91 µm; with three hair-like setae on segment I, two hair-like setae on segment II, two hair-like setae on segment III, one fleshy seta on segment IV, one fleshy seta + two hair-like setae on segment V, three fleshy setae + six hair-like setae on segment VI. Tentorial box 63-68 µm long, 50-58 µm wide. Labium 20-25 µm long, 30-33 μm wide. Spiracles ca. 15 µm long, ca. 7 µm wide across atrium. Legs: trochanter + femur 68-75 µm, tibia 30-40 μm, tarsus 43-53 µm; claw 12-14 µm; coxa with ca. six setae, trochanter with four setae, femur with five setae, tibia with four setae, tarsus with five or six setae; tarsal digitules unequal, large proximal digitule 25-32 µm long, small distal digitule ca. 20 μm long, claw digitules 13-15 µm long. Anal ring 17 µm wide, with six setae, each seta ca. 20 μm long. Pair of elongate caudal setae 143-163 µm long.

Dorsum. Derm beset with weakly sclerotic spots, each 2-5 µm in greatest dimension. Dorsal setae ca. 5 µm long; two longitudinal rows on each side of body, medial row with two setae on prothorax, and one seta on each segment from mesothorax to abdominal segment VII, submedial row with three setae on prothorax and one seta on each segment from mesothorax to abdominal segment I. Microtubular ducts each ca. 5 μm long, with rim of dermal orifice subelliptical, ca. 2 μm wide and 3 μm long, two longitudinal rows on each side of body, medial row with one duct on each segment from head to metathorax + abdominal segment VIII, and submarginal row with two ducts on prothorax, one duct on each thoracic segment and abdominal segments I and V (Note: it was an arbitrary decision to include the ducts on each side of head and abdominal segment VIII in the “medial” row). Dorsum delimited by fringe of 31-34 setae on each side of body (excluding caudal setae), each seta 9-15 μm long and 7-9 µm width at base above socket, deltate, with anterolateral margin sinusoidal and posteromedial margin straight; weakly sclerotic cuticle surrounding each setal socket, these sclerotic areas coalescing around the three most posterior fringe setae and the caudal seta, forming broad caudal sclerotization.

Venter. Ventral setae 2-5 µm long, in three longitudinal rows on abdomen; one elongate (ca. 18 μm long) seta medial of each coxa, three elongate setae (18-27 μm long) in longitudinal row on each side of head. Multilocular pores trilocular, 5 µm in diameter; one near each spiracle. Ventral lobe seta absent.

Notes. The first-instar nymphs of L. melliodorae are most similar to those of L. froggatti and L. lectularius , which also have (i) dorsal sclerotic spots (poorly developed in L. froggatti ); (ii) stout marginal setae subtended by patches of sclerotic cuticle; and (iii) broad caudal sclerotizations (but in L. lectularius , only the caudal seta and 1 enlarged fringe seta are part of the sclerotization). The first-instar nymphs of L. eucalypti lack both the sclerotized area surrounding the socket of each marginal seta and the broad caudal sclerotizations, but have dorsal sclerotic spots. The nymphs of all four species have a similar arrangement of ducts, pores and setae. The first-instar nymphs of L. melliodorae can be distinguished from those of L. eucalypti , L. froggatti and L. lectularius by the distinctive shape of the marginal setae: deltate, with anterolateral margin sinusoidal and posteromedial margin straight, and base broad (marginal setae of L. eucalypti mostly falcate, with setal base constricted; of L. froggatti falcate but shorter than those of L. eucalypti ; of L. lectularius more elongate, conical, with both margins straight).

Etymology.

The species name refers to the name of the host from which the type material was collected. The species epithet is in the genitive singular.

Material examined.

Holotype: Victoria: adult female, on slide: ex open pit gall on twig, Eucalyptus melliodora , Lower Plenty, 19 Dec 1971, JWB (ANIC). Paratypes: Victoria: two adult females, same data as holotype (ANIC); four adult females, three second-instar females, same data as holotype, except V-241, 12 Dec 1971 (BPBM); one parasitized second-instar female, same data as holotype, except 16 Oct 1971; four adult females, one second-instar female and eight first-instar nymphs, same data as holotype except 1 Jan 1972 (first-instar nymphs reared in lab from ovisac) (BPBM except one slide of nymphs in ANIC).

Additional material: two adult females, two second-instar females with pharate adults: ex pits on stems, Eucalyptus sp. sapling, 10 km NNW of Benalla, roadside, 36.48S 145.95E, 22 Jun 1996 and 25 Apr 1997, PJG (ANIC). New South Wales: one adult female: ex open pit twig gall, Eucalyptus sp., 15 miles [24 km] S of Kempsey, Pacific Highway, 26 Mar 1972, JWB (BPBM). South Australia: one adult female: under bark of E. viminalis , 5 km S of Mylor, Mt Lofty Ranges, 18 Nov 1979 MS Harvey and D Cukier (ANIC).