Paralecanium minutum 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 : 116-118

Paralecanium minutum Takahashi

( Fig. 48 )

Paralecanium minutum Takahashi, 1951 , 103. Type data: INDONESIA: Riau Islands, Rempang , host-plant not indicated. Syntypes, female. Type depository: EIHU, Sapporo, Japan .

Material examined. Holotype f: INDONESIA, Riouw Is., Rampang (almost certainly Riau Is., Kempang ), no host, Jan. 1946, R. Takahashi ( EHIU): 1/1adf (fg but well sclerotised and some details hard to discern).

Note. Takahashi (1951) states that this is the only specimen.

Slide-mounted adult female. Body almost round but slightly more pointed anteriorly; clearly showing some asymmetry, particularly ventrally. Length 1.9 mm, width 1.7 mm.

Dorsum. Derm fairly uniformly sclerotised with moderately large areaolations near margin, these becoming more obscure medially; almost all of dorsum with minute pale spots. Marginal radial lines absent, positions indicated by pores and setae, with perhaps 12 lines anteriorly between anterior stigmatic clefts, each side with 3 lines between clefts and 12 on abdomen. Abdominal clear areas absent. Dorsal setae considered to be present but only probable basal sockets found; perhaps only present submarginally. Dorsal pores of 2 sizes noted: (i) large dorsal pores, each 5–6 µm wide without obvious micropores, present in broad submedial bands, each band with 20–24 pores, probably in a sparse polygonal pattern, and (ii) smaller simple pores, each about 2.0 µm wide, sparse throughout; no minute pores noted. Anal plates with a rounded outer angle and anterior border subequal in length to posterior border, but length of plates greater than combined widths; setae uncertain but perhaps with 1 on outer margin near apex; no small pores visible; length of plates about 160 µm, combined width about 95 µm. Anogenital fold unclear but perhaps with 1 pair of small setae along anterior margin, each lateral margin with 1 seta at anterior end and another at posterior end; the end of each anal plate apodeme is somewhat sclerotised and extends anteriorly, where it expands and appears to fuse medially.

Margin. Margin characteristically sclerotised with minute corrugations, which form a shallow collar around each marginal setal socket. Marginal setae fan-shaped, almost round; width of each fan 25 µm, length 22 µm; with 95 setae anteriorly between anterior stigmatic clefts, each side with 33–38 setae between stigmatic clefts, and 95 or 96 along abdominal margin. Stigmatic clefts rather shallow, each with a very narrow entrance, details very hard to determine but probably with a single stigmatic spine, this indicated by what is thought to be a setal socket anteriorly on inner margin (see under Comments below). Eyespots each more or less round; width of socket about 58 µm; diameter of lens 16–17 µm.

Venter. Venter membranous apart from a broad marginal border, about 65 µm wide, with paler, branching radial lines throughout. Multilocular disc-pores hard to discern but present in bands on either side of genital opening and on preceding segment only, each side with possibly 5 on abdominal segment VII and 8–10 on segment VI. Spiracular disc-pores present in a narrow band between margin and each spiracle, with perhaps 8–16 in each anterior band and 12–14 in each posterior band. Ventral microducts not visible. Ventral setae only noted as medial pairs on abdominal segments V–VII. Antennae well developed, each with 6 segments; total length 163–175 µm; apical segment 40–43 µm long, apical seta 17 µm long. Clypeolabral shield small, about 90 µm long. Spiracles small; width of each peritreme 18 µm. Legs well developed; dimensions of hind leg (µm): coxa 53, trochanter + femur 75–77, tibia + tarsus 85–90 (some with a hint of segmentation); claw 7. Tarsal digitules slightly longer than claw digitules, with capitate apices; claw digitules both broad but one possibly slightly narrower than other; claw without a denticle; setal distribution: coxa 5; trochanter 1; femur 2; tibia 1 and tarsus 3.

Comments. Adult female P. minutum are immediately recognisable by the structure of the marginal sclerotisation and ornamentation, which forms narrow collars around the stem of each marginal seta. They are also thought to have only a single stigmatic seta in each cleft but all of these appeared to be missing in the present study—although Takahashi (1952) states “stigmatic clefts small, entirely closed within the margin, with a single (?) spine which is normal in shape, bluntly pointed and not reaching the margin.” However, each cleft does appear to have a single setal socket. Another feature that may be significant is the transverse sclerotisation at the anterior end of each anal plate apodeme, although this may occur more widely in more mature specimens.

Host-plant. Unknown.

Figures

FIGURE 48. Paralecanium minutum Takahashi, adult female.