Platylecanium mesuae Takahashi, 1950

Hodgson, Chris, 2025, Revision of the soft scale genus Platylecanium (Hemiptera: Coccomorpha: Coccidae), with descriptions of eight new species, Zootaxa 5646 (2), pp. 151-198 : 176-179

Platylecanium mesuae Takahashi

Platylecanium mesuae Takahashi, 1950: 58 ; Hodgson 2023: 561.

Material examined

Type material: MALAYSIA: Lectotype adf: upper labels: a small round label stating Lectotype, plus another label stating: Pres. by / Comm. Inst. Ent. / B.M. 1953.789, and a third label showing a map of the round cover slip and the position of the Lectotype, marked in red; lower label: Platylecanium / asymmetricum / Morr. var / mesuae Tak. / 29.vi.1943 / Mesua / Kuala / Lumpur / R. Takahashi (1/4 adff; NHML). There is also a specimen of another unknown soft scale species on the slide, covered in black ink (not P. mesuae ). The remaining (paralectotype) specimens are somewhat damaged, particularly the venter. In addition, several of them have nymphs inside. This is thought to be the only type slide of P. mesuae .

Note. The following description is a slightly modified version of Hodgson (2023), which was made from the lectotype plus the largest and smallest specimens.

Unmounted material. Unknown.

Slide-mounted adult female ( Fig. 10 ). Some parts of dorsum are covered in a broken glassy test. Body oval but asymmetrical, most obviously indicated by the position of the mouthparts and lengths of the stigmatic grooves. Body probably almost flat in life, length 2.7–3.3 mm; width 1.7–2.4 mm; stigmatic clefts distinct but narrow and sclerotised, anal cleft with sides adpressed, about 1/6 th of body length.

Dorsum. Derm rather evenly sclerotised throughout apart from: (i) quite strong sclerotisation in each stigmatic cleft; (ii) a fairly broad sclerotised area around anal plates; (iii) randomly shaped, lightly sclerotised areas around each clear area, approximately on abdominal segments II– VI; (iv) a quite wide membranous area around each eyespot, and (v) a radial membranous groove extending medially from each stigmatic cleft, those on short side 25–40 µm long and 50–65 µm long on long side. Derm on more sclerotised specimens also with oval-to-round areolations submarginally. Dorsal setae each very fine and setose, about 5 µm long, generally slightly bent, apparently situated on a membranous cone, present in a reticulate pattern, but setae much sparser medially where pattern vague; with probably a total of 47 marginal reticulation points with setae around margin, and 11 reticulation plates medially between anal plates and anterior margin. Dorsal pores of 2 types: (i) very small pores, possibly microducts, represented by unstained dots, each about 2 µm wide, present within reticulation lines of dorsal setae (not present within areolations); and (ii) small, convex preopercular pores found in groups associated with each clear area, each pore 4–6 µm wide, frequency as follows: (anteriormost) CA1 , 0; CA2 , 1–5 ; CA3 , 5–8 ; CA4 , 4–8 pores and CA5 (when visible), 0. Anal plates together quadrate, 128–133 µm long, combined width 120–130 µm, each plate with outer margins more-or-less straight and subequal in length; probably with four setae near apex, all very fine and short, each perhaps 3–5 µm long. Anogenital fold possibly without setae on anterior margin but with 3 short, very fine setae on each lateral margin, each seta about 3–8 µm long; anal plate apodemes fusing along anterior margin of anogenital fold. Anal ring bearing 6 setae, each about 150 µm long. Eyespot present on dorsum, located about half-way between margin and a point dorsad to antennal scape; width of lens 23–25 µm, greatest width of surrounding membranous area 65–85 µm .

Margin slightly crenulated, with marginal setae sometimes appearing to be set slightly onto dorsum. Marginal setae finely setose, with some setae bending anteriorly and others posteriorly, each seta about 10–15 µm long, slightly curved; with a group of 0–3 (mostly 2 or 3) at each reticulation point; absent from anal lobes and from along outer margins of each stigmatic cleft. Stigmatic clefts each narrow at margin, widening inwardly, strongly sclerotised along innermost margin; each cleft containing 3 spinose stigmatic setae, each bluntly pointed and more-or-less parallel sided; medial spine rather variable in length (but some thought to be broken), 38–55 µm long, each lateral spine 28–43 µm long.

Venter. Derm membranous. Pregenital disc-pores mostly with 10 loculi, present on segments VII and VI only, with, on each side, VII with 12–19 and VI with 17–22. Spiracular disc-pores mostly with 5 loculi but very small, present in rows more-or-less 1 pore wide between each spiracle and margin, with many fewer on short side, as follows: side with short bands with 5–10 (mainly 5 or 6) per band, side with longer bands with 14–22. Ventral microducts minute, each perhaps 1.5 µm wide, sparse, distribution uncertain. Ventral setae: with perhaps 2 pairs of interantennal setae; 1 pair of pregenital setae, each 40–55 µm long; other setae all setose and very short, each 3–5 µm long, situated on a rather convex basal socket. Antennae reduced, with a broad scape and with other segments fused; setae restricted to near apex, with 5 fleshy setae; each antenna 13–33 µm long. Clypeolabral shield about 113–120 µm long. Spiracles small, width of each peritreme 23–31 µm; supporting bars narrow. Legs reduced to minute stubs, each about 2–3 µm long, without digitules; perhaps sometimes absent.

Comments. Platylecanium mesuae can be diagnosed by the following combination of character-states: (i) body broadest posteriorly; (ii) anal plates about as long as their combined widths; (iii) each anal plate without a cleft on underside of inner margin; (iv) margin crenulated; (v) marginal setae about twice as long as dorsal setae; (vi) preopercular pores clearly larger than other dorsal pores; (vii) preopercular pores only present in association with posterior 3 pairs of clear areas; (viii) each stigmatic cleft with 3 long, narrow stigmatic spines; (ix) multilocular disc-pores restricted to abdominal segments VII and VI; (x) legs very reduced, mostly to a claw, without digitules, and (xii) antennae very reduced. The above description differs slightly from that of Takahashi (1950) in that he considered that the marginal setae were not in groups, whereas they are clearly in groups associated with the marginal reticulation points.

In having: (i) a crenulated margin; (ii) reduced antennae; (iii) a body less that twice as long as broad, and (iv) multilocular disc-pores mostly with 10 loculi, P. mesuae is very similar to P. watsoniae (described as new below), and symmetric P. asymmetricum . Platylecanium mesuae differs from P. watsoniae as follows (character-states for P. watsoniae in brackets): (i) anal plates about as long combined widths (clearly much longer than wide); (ii) apodemes on either side of anterior end of anal cleft fused anteriorly (clearly separate); (iii) possibly with anterior margin of anogenital fold without setae (with 2 pairs of setae); (iv) each stigmatic cleft without marginal setae along outer margins (with 2 or 3 marginal setae), and (v) dorsal setae finely setose, and each less than half length of a marginal seta (robustly setose, each more than half length of a marginal seta). Platylecanium mesuae differs from P. asymmetricum in: (i) the absence of a deep cleft underneath the inner margin of each anal plate, and possibly (ii) in the absence of marginal setae along inner margins of each stigmatic cleft.

Platylecanium mesuae is currently only known from the original collection in Malaysia, on Mesua sp. ( Calophyllaceae ).

Figures

FIGURE 10. Platylecanium mesuae Takahashi, adult female.