Discochiton malainum (Takahashi)

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: 37-38

publication ID

http://doi.org/ 10.11646/zootaxa.4443.1.1

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scientific name

Discochiton malainum (Takahashi)

comb. n.

Discochiton malainum (Takahashi)   comb. n.

( Fig. 12 View FIGURE 12 )

Paralecanium malainum Takahashi, 1950   , 54. Type data: MALAYSIA: Kuala Lumpur, Batu Arang   , Selangor and SINGAPORE, on mangosteen and Palaquium   sp   . Syntypes, female. Type depository: BMNH, London , U.K.  

Paralecanium malaianum Takahashi. Misspelling   on type slides.

Material examined. Lectotype f and paralectotype ff (here designated): MALAYSIA, top label: Mangosteen / Type (in red on another small round label), Pres. by / Com. Inst. Ent. / B.M. 1953-789 (on a small white label) / R. Takahashi; bottom label: Paralecanium   / malaianum   / Takahashi / 13.III.1943 / Kuala / Lumpur (BMNH): 1/16adff (mainly poor, without venters; lectotype on right hand side, second from bottom). Malaysia, top label: small round label with Type in red; bottom label: Paralecanium   / malaianum   / Takahashi / 13.III.1943 / Kuala Lumpur / R. Takahashi (BMNH): 1/8adff (mainly poor) (Envelope states Pres. Selangor Museum, Malaya). [Note the spelling of the species name on the slide labels! It is given as malainum   in the text of Takahashi (1950)].

Other material. MALAYSIA, Selangor, on Garcinia mangostana   , 21.iii.1950, no coll. (BMNH (BM06086)): 5/16adff (f-p, all missing venters). Perak, on G. mangostana   , 21.ii.1948, H.T. Pagden (BMNH (BM 05281)): 2/3adf (p, all missing venters; labelled P. nr. mancum   ).

PHILIPPINES, Palawan, Honda Bay , small island., 7.ii.1988, on upper leaf surface of unidentified sapling, J.H. Martin #5247 ( BMNH): 3/10adff (g-p, about half missing venters), + 3 first-instars (fg) + 1 second-instar male (fg) + 2 female instars (vp).  

Note. The following description is based on a selection of type specimens.

Slide-mounted adult female. Body broadest posteriorly or nearly circular, but often showing signs of asymmetry, particularly on venter. Length 2.5–5.0 mm, width 1.9–4.5 mm.

Dorsum. Derm rather uniformly sclerotised but with a broad band of elongate-oval areolations running around entire body close to margin, long axis of each areolation parallel with margin; also with a submarginal band of larger blocks of rounder areolations; rest of dorsum rather uniformly sclerotised; derm medially with abundant minute pale spots and some specimens with an indistinct polygonal pattern. Stigmatic rays present; marginal radial lines not apparent but indicated by the distribution of pores and setae, with probably 13 lines on head between anterior stigmatic clefts; each side with 5 between stigmatic clefts and 13 on abdomen. With 4 pairs of abdominal clear areas submedially and another near apex of each anterior stigmatic radial band. Dorsal setae each spinose, with parallel sides and a blunt (occasionally looking a bit pointed) to slightly capitate apex, each 13–15 µm long with a well-developed basal socket about 5 µm wide; frequent in a sparse polygonal pattern submarginally and submedially but absent medially; each seta usually situated in a clear area of derm lacking pale spots, and most setal sockets each apparently associated with a dorsal pore. Preopercular pores only associated with posteriormost clear areas but these pores forming a group of 19–24 pores just mesad of each posterior clear area (not around it), often on an area of more heavily sclerotised derm on older specimens; each pore distinctly convex and 3–4 µm wide. Small simple pores each about 3 µm wide, appearing as small non-sclerotised round areas in a polygonal pattern throughout. Anal plates rather small and elongate, together narrowly quadrate, with anterior and posterior margins subequal in length; each plate with three small setae near posterior apex, plus 1 or 2 small pores medially; length of plates 186–200 µm, combined width 150–155 µm. Anogenital fold with 3 minute setae at each corner of anterior margin, each lateral margin with 1 seta at anterior end and another at posterior end.

Margin. Marginal ornamentation: thin radial lines, some forming sclerotised blocks, others V-shaped groups, mostly each extending to about depth of a marginal setal socket, with mostly 3–6 blocks between 2 setae. Marginal setae almost circular; width of each fan about 35–45 µm, length 30–35 µm; with about 97–106 setae anteriorly on head between anterior stigmatic clefts; each side with 42–49 between stigmatic clefts and 88–100 on abdomen. Stigmatic clefts quite deep, each with a narrow entrance, a sclerotised inner margin and 3 short, rather parallelsided, blunt stigmatic spines; spines either subequal in length or median spine slightly longer, each 35–47 µm long, lateral spines each 33–35 µm long. Eyespots: each with socket about 95 µm wide, diameter of lens 28–30 µm.

Venter. Derm membranous, with a narrow marginal band about 45–60 µm wide, slightly darker than submargin. Multilocular disc-pores frequent on either side of genital opening and on preceding two segments only, each side with 19–22 on abdominal segment VII, 24–30 on segment VI and 19–24 on segment V. Spiracular discpores present in a narrow band mostly 1 pore wide between margin and each spiracle; number of pores uncertain but perhaps 9–23 in each band (9–19 on material from Palawan); posterior bands each with sparse pores or a gap near spiracle. Ventral microducts minute, present in a dense group just posterior to and on either side of labium; sparsely present elsewhere. Ventral setae: with 2 pairs of interantennal setae; pairs of long pregenital setae on segments VII –V (that on VII 75 –85 µm long); other setae small and sparse. Antennae reduced, each with 3 segments, segments III –VI fused; total length 115–130 µm. Clypeolabral shield 125 µm long. Spiracles: width of each peritreme 38–40 µm. Legs entirely absent.

Comments. Adult female D. malainum   belong to the group of Discochiton   species that lack legs and have blunt, often capitate dorsal setae but differ from all other Discochiton   species in the distribution of the preopecular pores, which, in D. malainum   , are in a fairly tight group just mesad of CA4, sometimes in an area of sclerotised derm on older specimens, whereas they occur in a loose group surrounding each clear area in the other Discochiton   species.

Host-plants. Garcinia mangostana   ( Clusiaceae   ). Unconfirmed host plant: Palaquium   sp. ( Sapotaceae   ).