Platylecanium nepalense Takagi 1975

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 : 179-182

Platylecanium nepalense Takagi 1975

Platylecanium nepalense Takagi, 1975: 7 .

Platylecanium hepalense Takagi, 1975 ; Tang 1991: 133. Misspelling of species epithet.

Material examined

Type material not seen.

MALAYSIA: Five slides containing 17 adult females: left label: Platylecanium / nepalense / Takagi / det. C.J. Hodgson / J.H. Martin 8511; right label: sapling, upper / surfaces of leaves / W. MALAYSIA / N. Sembilan / Ulu Klawang / Jeram Toi Valley / 20 March 2011 (5/17 adff, good) ( NHML) .

Note: The description below is based on eight non-type specimens, with data from Takagi’s (1975) description, followed by those from Joshi & Firake (2020) in brackets.

Unmounted material. Takagi (1975) does not describe the unmounted specimens, but Joshi & Firake (2020) do so as follows “Dorsal surface coated with a delicate transparent waxy layer which is thickened in definite polygonal plates arranged in longitudinal series around dorsomedial ridge that runs from anal plate to prothorax. Marginal wax becoming more pronounced with age. Females developing on the leaf edge and adjacent to the midrib tending to become asymmetrical. Ventral position of the live female indicates absence of legs and presence of very short antenna and clear demarcation of marginal and submarginal areas. Adult female developing away from midrib or leaf margin perfectly symmetrical. Margin with regular rectangular thick wax filaments which are shed even by strong wind current. Very well marked marginal area yellowish brown and submarginal area brown. Median area golden yellow with central area orange-brown. Transparent waxy layer producing irregularly polygonal 25–27 depressions arranged symmetrically around both the sides of dorsomedial ridge. These depressions having carapace pattern. Black eyes prominent.”

Slide-mounted adult female ( Fig. 11 ). Rather flat, body symmetrical (mainly asymmetrical; both), roundly oval, length 4.25‒5.2 (4.6‒5.8; 3.8‒5.0) mm, width 3.3‒4.1 (‒; 2.6‒4.0) mm; anal cleft about 1/6 th of body length.

Dorsum. Derm becoming sclerotised at maturity, sclerotisation appearing first along reticulation lines medially and then spreading out around each reticulation plate and expanding laterally into marginal areas; remaining pale around each eyespot. With complete pale band of abundant areolations set a short distance in from margin, each areolation quite large. Reticulation plates probably in 4 longitudinal bands on each side, those medially largest. Marginal reticulation points reasonably distinct, with 13 on head between anterior stigmatic clefts and with, on each side, 4 between stigmatic clefts and 13 on abdomen (latter including line close to anal cleft, often difficult to distinguish). Distinct unsclerotised ray arising from each stigmatic cleft, each extending to dorsad to a spiracle or even a little further medially, only becoming visible with maturity due to sclerotisation of dorsum. Dorsal setae each 7‒9 (‒; 7‒8) μm long (only slightly shorter than or subequal in length to a marginal seta), setose, mostly distinctly curved, each in a socket about 4‒5 μm wide - distinctly larger than that for a marginal seta, with many setae raised on a fleshy cone, some cones long, up to 40 μm long, each with seta on apex; setae restricted to within reticulation lines and most abundant towards margin, becoming scarcer medially. Clear areas present as in diagnosis, each with a group of preopercular pores, each pore about 5‒6 μm wide and possibly slightly convex with a distinct border; pores distributed mainly posterolateral to each clear area, as follows: (anteriormost) CA 1, 4‒8 (1‒12; 1‒15); CA 2, 4‒10 (10‒19; 1‒10); CA 3, 6‒11 (12‒21; 0‒19); CA 4, 6‒11 (10‒24; 0‒15). Dorsal microducts represented by small clear spots in derm on mature specimens, each spot 4‒6 μm wide, but occasionally with a small round pore visible, each about 1.5 μm wide; pores more abundant than dorsal setae and also restricted to within reticulation lines. Anal plates each 243‒252 (‒; 290‒325) μm long, combined width 134‒155 (‒: 120‒180) μm; together clearly significantly longer than broad, each with anterior margin slightly shorter than posterior margin; with 4 setae near apex, most 5‒7 μm long but apical seta up to 10 μm long, present as diagnosis; often with 1 small pore medially; underside of each plate showing nothing distinctive. Anal tube about as long as anal plates; anal ring with 6 setae, each about 320‒350 μm long. Anterior margin of anogenital fold with 2 short fine setae on each side, 2 pairs of fine setae in middle of each lateral margin (often very difficult to see) and 1 short seta at posterior end of each apodeme. Eyespots, each more-or-less round, located away from margin on dorsum; width of each lens about 25 μm, in unsclerotised area about 30‒40 (35‒40; 40‒50) μm wide.

Margin. Margin not crenulated. Marginal setae all short, each about 8‒15 (‒; 10‒12.5) μm long (only slightly longer than dorsal setae); setose, occurring mainly in groups of 2‒4 (‒; 0 or 1) approximately associated with each marginal reticulation point; with about 25‒45 (sparse; 2‒5) between anterior stigmatic clefts, with, on each side, 11‒ 19 (sparse; 0‒2) setae between stigmatic clefts, and 25‒39 (sparse; 1‒6) setae along abdominal margin. Stigmatic clefts quite deep, each with outer margins of cleft almost touching; inner part of cleft quite broad with inner margin strongly sclerotised; with 5‒9 (4‒7; 5 or 6) stigmatic spines, mainly subequal in length or with outer spines in each group shortest, each 20‒54 (‒; 37.5‒62.6) μm long; each outer cleft with 1‒3, rarely 0, setae on each margin. Anal cleft with margins touching; derm finely granulated along posterior margin of each anal plate.

Venter. Multilocular disc-pores each 7‒8 μm wide, mostly with 10 loculi (‒; 6‒11), frequent on either side of genital opening and on preceding segment only; numbers on each side: VII, 10‒22 (15‒23; 24‒43); VI, 22‒37 (22‒33; 31‒47). Spiracular disc-pores, each about 3.0‒3.5 μm wide, mostly with 5 loculi, present in a narrow band between margin and each spiracle; with (possibly) 22‒40 (‒; 8‒31) in each anterior band and 33‒47 (‒; 16‒38) in each posterior band (maximum 39‒40 in each band, according to Takagi). Ventral microducts minute, rather sparsely distributed throughout. Ventral setae: interantennal setae absent; long setae present on abdominal segments VII and VI; lengths: VII each 50‒85 (40; 50‒65) μm, and VI each about 25 μm; setae sparse elsewhere but shorter marginally than medially. Antennae very reduced, segmentation rather obscure but some segments usually visible, with a basal scape, a further segment and 3 apical segments; total antennal length 73‒101 (60‒80; 50‒70) μm. Clypeolabral shield 120‒126 (‒; 125) μm long. Spiracles small, width of each peritreme 40‒50 (‒; 25‒40) μm. Legs all minute, when detectable, more-or-less reduced to a claw without digitules (absent; absent).

Comments. The above redescription differs from that given by Joshi & Firake (2020) in that their anal plates were significantly longer than in the Malaysian specimens; this description also differs from both Joshi & Firake (2020) and Takagi (1975) in the frequency of the marginal setae, which was apparently much higher on the Malaysian specimens. Nonetheless, these specimens are otherwise very similar and are here considered to be conspecific.

The specimens described here were all symmetrical. The original type series, collected in Nepal (Balaju, at 1400 m), were asymmetrical to varying degrees ( Takagi, 1975). Joshi & Firake (2020) indicated that some of their specimens (from India, Umiam, Meghalaya) showed asymmetry whereas others did not. It is considered here that asymmetry is a phenotypic character, as argued in the Introduction above. In all other respects, the above description fits very closely that of Takagi (1975) and Joshi & Firake (2020).

Platylecanium nepalense is recognisable by the following combination of character-states: (i) large body size; (ii) margin not crenulated; (iii) the characteristic patterns of sclerotisation on dorsum on mature specimens; (iv) marginal setae subequal to or only slightly longer than dorsal setae; (v) anal plates clearly longer than their combined widths; (vi) underside of each anal plate showing nothing distinctive; (vii) preopercular pores associated with all four clear areas; (viii) usually with at least 6 stigmatic spines in each stigmatic cleft (range 4‒9); (ix) multilocular disc-pores restricted to abdominal segments VII and VI; (x) legs very reduced, mostly to a claw, without digitules, and (xi) antennae reduced but with some segmentation visible. Apart from P. vanda , sp. nov. (described below), P. nepalense is immediately separable from all other known Platylecanium species by the large number of stigmatic spines in each cleft (4‒9). However, P. nepalense and P. vanda are morphologically very similar but can be differentiated as follows: P. nepalense is a large species (mature (sclerotised) specimens 4.25‒5.8 mm long), clearly larger than mature P. vanda (only 2.0‒ 4.3 mm long); the smaller size of P. vanda is also clearly shown by the size of the anal plates, more than 240 μm long in P. nepalense but less than 210 μm long in P. vanda . The two species are also found on very different hosts ( P. nepalense on Anacardiaceae and Arecaceae and P. vanda on Orchidaceae ). It is also possible that they differ in the frequency of the marginal setae, with P. nepalense having mainly 2‒4 setae at each reticulation point, but with only 0 or 1 seta at each of these points on P. vanda . However, Joshi & Firake (2020) reported very few marginal setae (a maximum of 13 setae per side) and so this character may vary geographically.

It should be noted that there are a few minor errors in the paper by Joshi & Firake (2020). In their fig. 2, l = the spiracle, m = the multilocular disc-pores, n = the submarginal setae, o = prevulvar seta, and p = the antenna. There is no habitus photograph (q). In addition, in the last couplet of their key, the lengths given for P. elongatum and P. cyperi have been switched– P. cyperi is the larger of the two species.

Platylecanium nepalense is now known from Nepal, on an Anacardiaceous plant, India on Dypsis lutescens and Phoenix sylvestris ( Arecaceae ), China on Calamus inermis ( Arecaceae ) and Malaysia on an unknown host.

Immature stages: Joshi & Firake (2020) also described and illustrated the field characters of the immature stages of P. nepalense : “Appearance in life: Crawlers yellow. Second-instar nymphs transparent, anal plates brownish opaque, anal and stigmatic clefts white, margin with thin wax filaments. Third-instar nymphs with marginal and submarginal areas translucent, median area opaque yellow with central area turning darker.”

Figures

FIGURE 11. Platylecanium nepalense Takagi, adult female.