Discochiton vacuum (Morrison) Chris J. Hodgson & Douglas J. Williams, 2018

Chris J. Hodgson & Douglas J. Williams, 2018, Revision of the soft scale genus Paralecanium (Hemiptera: Coccomorpha: Coccidae) with the introduction of three new genera and twenty new species, Zootaxa 4443 (1), pp. 1-162 : 73-77

Discochiton vacuum (Morrison) comb. n.

( Figs 29 and 30 )

Paralecanium vacuum Morrison, 1921 , 674. Type data: SINGAPORE: on Ficus sp. Syntypes, female. Type depository: USNM, Washington, U.S.A.

Material examined. Lectotype f and paralectotype f (here designated): SINGAPORE: top label: TYPE; bottom label: Paralecanium / vacuum / Green / on Ficus sp. / Singapore / coll. I.H. Burkill (BMNH): 1/2adff (g; lectotype bottom (or right-hand) specimen). The authorship on the slide is clearly wrong and has been corrected on the envelope; envelope also states “from type material”. Singapore: left label: Paralecanium / vacuum Morr. / on Ficus sp., / Singapore / I.H. Burkill, coll. (USNM): 1/1adf (vp; possibly part of type series). Singapore: left label: Paralecanium / vacuum Morr. / on coconut / Singapore, S.S. / C.P. Clausen, coll. / Nov. 1929 (USNM): 1/1adf (g).

Other material. BRUNEI, on Annona muricata [ Annonaceae ], 1971, Khasim bin Ahmad (BMNH): 3/3adff (fg).

MALAYSIA (as Federated States of Malaya), Sepang, on C. nucifera , 22.vii.1927, G.H. Corbett (USNM): 1/ 1adf (p, missing most of venter; labelled P.? vacuum ). Kuala Lumpur, on Cinnamomum zeylanicum , 14.iv.1932, Ent. Div. #8468 (BMNH): 1/1adf (fg; very few preopercular pores). Sarawak, on soursop [ Annona muricata ], 1.xii.1961, C.R. Wallace (BMNH): 1/1adf (f). Sarawak, Krokop, on coconut, 2.viii.1962, W. Crocker #3772 (BMNH): 1/1adf (fg).

SINGAPORE, intercepted at San Juan , U.S.A., #5987, on leaf of an orchid plant, 22.ix.1974, G. Vasquez ( USNM): 2/1adf (g, possibly a young specimen) + 1 second-instar male nymph (g) . Singapore, no other site data, on Ficus kurzii , 17.iii.1940, R. Takahashi ( TARI): 1/1adf (vp).

Note. The description is based on good Singapore type specimens with some data for venter also taken from other non-type specimens.

Slide-mounted adult female. Body broadly and roundly oval, showing no asymmetry. Large, length 6.4–9.5 mm, width 5–8 mm.

Dorsum. Derm rather uniformly sclerotised, with a broad submarginal area of medium-sized areolations, these very obscure or absent medially; derm between areolations with some darker spots. Marginal radial lines obscure but indicated by position of larger dorsal pores, with perhaps 12–14 lines around head, each side with 5 between stigmatic clefts and 12 or 13 lines along abdominal margin. Stigmatic rays present. Abdominal clear areas numbering 5 pairs and another pair present on prothorax. Dorsal setae of 2 sizes present, some on end of a membranous tube (as on P. browni ) each tube up to about 85 µm long: (i) larger setae, each 20–85 µm long (the shortest being situated more laterally) and finely spinose, present in two submedial bands extending from anal plates to head, each band with 2–32 setae (but most broken off on type series; see note below); and (ii) small setae each with a sharp apex, 8–18 µm long with a basal socket 5–8 µm wide, generally few, often more or less restricted to posterior 4 or 5 pairs of marginal radial lines, usually each associated with pale areas of derm surrounded by a band of convoluted derm; short setae absent medially. Preopercular pores convex, each 7–8 µm wide, distributed as follows: CA1 with 4–25, CA2 with 11–25, CA3 with 12–25 and CA4 with 11–29 pores. Other small dorsal pores of 2 sizes present, mainly located submedially: (i) a small dark pore about 2.5 µm wide, and (ii) a small simple pore about 1.0–1.5 µm wide, both sparse in a polygonal pattern throughout, apart from medially. Anal plates together clearly longer than wide, but with anterior and posterior margins subequal in length; each plate with 4 setae near posterior apex plus 1 or 2 small pores medially; length of plates 340–370 µm, combined width 225–250 µm. Anogenital fold with 4–6 minute setae at each corner of anterior margin, each lateral margin with 1 longer seta anteriorly and another at posterior end. Anal ring with 6 setae, longest seta about 475–490 µm long.

Margin. Marginal ornamentation present in the form of shallow castellations, each with fine radial lines or ridges. Marginal setae broadly fan-shaped; width of each fan about 19–58 µm, length 37–60 µm; with about 133– 215 setae anteriorly on head between anterior stigmatic clefts, each side with 47–112 between stigmatic clefts and 135–187 on abdomen. Stigmatic clefts quite deep, each with a narrow entrance, a sclerotised inner margin and with 3 (one specimen with 5 in one cleft) short, stout, bluntly-pointed stigmatic spines, each subequal in length or middle spine longest, each 16–40 µm long. Eyespots, each socket about 105–140 µm wide; diameter of each lens about 30–40 µm.

Venter. Derm membranous, without a ventral marginal band. Multilocular disc-pores abundant around genital opening and on preceding two segments only, each side with 9–19 pores on abdominal segment VII, 27–49 on segment VI and 17–37] on segment V. Spiracular disc-pores present in a broad band between margin and each spiracle, with 27–65 pores in each anterior band and 19–57 in each posterior band, the latter band with a break medially. Ventral microducts minute, present in a dense group just posterior to and on either side of labium; also sparsely present elsewhere. Ventral setae: with 2 pairs of small interantennal setae; pairs of pregenital setae on segments VII–V (that on VII about 90–100 µm long). Antennae reduced, with only 3–5 segments but with some peudosegmentation, so sometimes appearing 5 or 6 segmented; without segmentation between segments IV–VI; total length 105–135 µm; apical seta short, each 16–20 µm long; setal distribution: scape 2, pedicel 0, III 0, IV with 2 fleshy setae (and therefore segments IV and V fused), and VI with 3 fleshy setae + 2 stiff setae. Clypeolabral shield 125–150 µm long. Spiracles each with peritreme 65–90 µm across. Legs present, as small stubs mostly each 7–10 µm wide at base and 5–10 µm long [one metathoracic leg stub apparently 2 segmented, 16 µm wide at base and 25 µm long]; most legs with 1 or 2 setae on derm near each stub.

Comments. Adult female D. vacuum belong to the group of Discochiton that have preopercular pores associated with all four abdominal clear areas but differs from all others in having: (i) leg stubs, (ii) long, rather spinose, setae in submedial bands on the dorsum, and (iii) broad spiracular disc-pore bands. However, it is here considered that the long setae are easily broken off and, therefore, most setae appear to be represented only by their basal sockets (which might be mistaken for large, sclerotised dorsal pores). For a discussion of the long fleshy tube-like structures, see under “Dorsal setae on apex of membranous tubes” in the introductory morphology section on p. 8.

Host-plants. Ficus sp., Ficus kurzii (Moraceae) ; Cocos nucifera (Arecaceae) ; Annona muricata (Annonaceae) ; Cinnamomum zeylanicum (Lauraceae) ; Orchidaceae . Unconfirmed plant host: Rhizophora sp. ( Rhizophoraceae ).

Figures

FIGURE 29. Discochiton vacuum (Morrison), adult female. Type series, Singapore, on Ficus sp.

FIGURE 30. Discochiton vacuum (Morrison), adult female. Singapore, on orchid leaf.