Discochiton crenulatum Hodgson

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 : 24-26

Discochiton crenulatum Hodgson spec. n.

( Fig. 6 )

Material examined. Holotype f: PAPUA NEW GUINEA: left label: Paralecanium / New Guinea / on Orchidaceae / 8-7-78 leaf / Los Angeles 19306 / V. M c Donald / Balsam; right label: Discochiton / crenulatus / Hodgson / Holotype ( USNM): 1/1adf (g, fairly mature). Paratype ff: left label: Paralecanium / New Guinea / ex Orchidaceae leaf / 11-7-78 / Los Angeles 19706 / V. M c Donald / Balsam; right label: Discochiton / crenulatum / Hodgson Paratype ff ( USNM): 1/3adff (g, all young).

Also seen: Papua New Guinea, West New Britain Prov., Kimbe , on coconut, 16.vii.1986, R.N.B. Prior CIE 18111 ( BMNH): 1/1adf (f, missing venter – but stigmatic clefts characteristic).

Note. The description is based on all the type specimens.

Slide-mounted adult female. Body oval, broadest across abdomen. Length 4.0– 7.5 mm, width 3.0– 5.5 mm.

Dorsum. Derm rather uniformly sclerotised but, on holotype, with a pattern of stronger sclerotisation medially; areolations present submarginally and submedially, almost round to oval, tending to be grouped (most pronounced around clear areas, eyespots and ends of each stigmatic ray); derm with abundant minute pale spots; derm around anal plates becoming heavily sclerotised with small oval areolations. Marginal radial lines absent but indicated by lines of pores and setae, with 13 or 14 ‘lines’ on head between anterior stigmatic clefts, each side with 5 between stigmatic clefts and 13 on abdomen; with long stigmatic rays present. With 4 pairs of abdominal clear areas and another at apices of anterior stigmatic rays. Dorsal setae each finely spinose to setose, with a flagellate apex, each about 12 µm long with a strongly sclerotised basal socket; those located submarginally and submedially each in a membranous area about 8 µm wide; frequent in a sparse polygonal pattern but absent medially. Preopercular pores present, each pore strongly convex and about 3.0–3.5 µm wide; none associated with CA1 & CA2, but 4–7 pores associated with CA3 and 8–11 with CA4. Other dorsal pores of two sizes: (i) larger pores, each about 4.5 µm wide, present in a sparse polygonal pattern throughout, and (ii) smaller pores, each about 1 µm wide in a unsclerotised spot about 1.5 µm wide, perhaps more randomly distributed. Anal plates together narrowly quadrate, with anterior and posterior margins subequal in length; each plate with 4 minute setae near posterior apex, plus 0 or 1 small pores a little more anteriorly; length of plates 270–305 µm, combined width 225–255 µm. Anogenital fold with 3 or 4 minute setae at each corner of anterior margin, each lateral margin with 1 at anterior end and another posteriorly.

Margin. Margin with shallow corrugations and numerous very short radial lines. Marginal setae broadly fanshaped, each clearly wider than long, 40–45 µm wide, about 23 µm long; numbering about 117–161 setae anteriorly on head between anterior stigmatic clefts, each side with 39–65 between stigmatic clefts and 95–142 on abdomen. Stigmatic clefts quite deep, with a narrow entrance; each sclerotised inner margin with a saw-like (crenulated) edge and each margin broadly sclerotised with 12–18 spiracular disc-pores within sclerotisation. Each cleft with 3 stigmatic spines subequal in length, each spine 30–40 µm long, parallel-sided with a blunt apex, some slightly bulbous basally. Eyespots large, each in a clear socket 125–140 µm wide; diameter of lens about 33–35 µm.

Venter. Derm membranous, with a narrow marginal band about 60–90 µm wide. Multilocular disc-pores frequent on either side of genital opening and on preceding segment only, each side with 20–31 on abdominal segment VII and 20–40 on segment VI. Spiracular disc–pores present in a broad band up to about 4 pores wide, with 47–70 pores in each anterior band and 50–70 in each posterior band (of which 12–18 in sclerotised area of each cleft), posterior band always without pores in middle section. Ventral microducts minute, present in a dense group just posterior to and on either side of labium, sparse elsewhere. Ventral setae: with 2 pairs of short and 1 pair of longer interantennal setae; pairs of long pregenital setae on segments VII–V (those on VII each 75 µm long); with a group of 8–14 long setae laterad to anterior end of anal cleft; small setae frequent medially just anterior to vulva on abdominal segment VII and in submedial groups segmentally between anal area and posterior spiracle; otherwise ventral setae very sparse and submarginal setae sparse and extremely short. Antennae reduced, each with segmental divisions between most segments obscure or absent; total length 115–145 µm; apical segment short, 16– 18 µm long; apical setae each 20–23 µm long. Clypeolabral shield 125–135 µm long. Spiracles: width of each peritreme 50–60 µm. Legs reduced to small stubs but often with some segmentation and a minute claw.

Comments. Adult female D. crenulatum spec. n. are extremely similar to those of D. browni (described as new above); both are without multilocular disc-pores on abdominal segment V. They differ as follows (characterstates for D. browni in brackets): (i) preopercular pores restricted to CA3 and CA4 only (associated with all four pairs of abdominal clear areas, although fewer associated with CA1 and CA2); (ii) legs better developed, showing some segmentation (just simple stubs, with no segmentation), (iii) dorsal setae parallel-sided, only narrowing slightly to a blunt apex (mostly narrowing to a point), and (iv) ventral setae frequent in bands across abdominal segments (very few). It is possible that these two species could be geographic variants of the same species but the above differences are sufficient to separate them at present.

Host-plants ( Cocos nucifera , Arecaceae ); Orchidaceae .

Name derivation. The name crenulatum is a Latin adjective and refers to the saw-like (crenulated) margins to the stigmatic clefts.

Figures

FIGURE 6. Discochiton crenulatum Hodgson, spec. n., adult female.