Discochiton bambusae Choi & Lee, 2023

Choi, Jinyeong & Lee, Seunghwan, 2023, A new species of Discochiton Hodgson & Williams (Hemiptera: Coccomorpha: Coccidae) on bamboo from Myanmar, Zootaxa 5353 (5), pp. 479-487 : 480-484

Discochiton bambusae Choi & Lee sp. n.

( Figs 1–4 )

Material examined. Holotype: 1 adult female mounted on a slide, Myanmar, Shan State / Ywangan / 21°22′48″N 96°47′87″E / coll. Jinyeong Choi / 25.v.2018 / Bambusa tulda (Poaceae) ( SNU). Paratypes: 9 adult females mounted singly on slides, same data as holotype ( SNU); 5 first-instar nymphs mounted together on 1 slide, same data as holotype ( SNU).

Diagnosis. Legs with all segments much reduced in length. Sclerotized plates present on venter, forming bands or patches submedially on body. Dorsal abdominal clear areas present in 4 pairs. Antenna 5–7 segmented. Each stigmatic cleft with 10–16 stigmatic spines. Dorsal marginal radial lines numbering about 22 around anterior margin of head, and each side with about 6 between stigmatic clefts and 18 on abdomen.

Description

Unmounted material ( Fig. 1 ). Body of adult female flat and broadly oval. Body camouflaged on bamboo, greenish or yellowish ( Fig. 1B, C ). Dorsal surface sclerotized, translucent and reticulated, with many indentations ( Fig. 1C ). Ventral surface also slightly sclerotized, almost transparent but with white translucent areas submedially on body ( Fig. 1D ); central concave brood space also present ( Fig. 1D ). First-instar nymphs reddish, elongated oval ( Fig. 1E, F, G ).

Slide-mounted adult female ( Figs 2 and 3 ). Body circular to oval (broadest across abdomen), 10.1–14.5 mm long and 7.9–11.9 mm wide.

Dorsum. Derm uniformly lightly to heavily sclerotized, with abundant areolations and small pale spots, some forming a polygonal pattern medially. Stigmatic rays broad, extending medially from each stigmatic cleft. Marginal radial lines indistinct, indicated by distribution of pores and setae; with about 22 on head between anterior stigmatic clefts, and on each side with about 6 between stigmatic clefts and about 18 on abdomen. Dorsal setae mostly flagellate but also rarely spinose, variable in length, each 6–57 μm long, with a broad basal socket 7–10 μm wide; sparsely present. Abdomen with 4 pairs of grouped clear areas (CA) submedially, numbered from anterior to posterior ( Fig. 2K ), each group surrounded by preopercular pores, each pore roundly convex, 3–6 μm wide, present as follows (number of clear areas in each group in brackets): CA1 with 22–40 (1–4), CA2 25–48 (1–3), CA3 31–43 (2–4) and CA4 with 29–40 pores (1–3). Other dorsal pores each 2–3 μm wide, each consisting of a ductule associated with an unsclerotized pale area, these pores forming a polygonal pattern medially and present in marginal radial lines with setae. Anal plates rather elongate, together quadrate, length of plates 251–293 μm, combined width 216–290 μm; each plate with anterior margin usually shorter than posterior margin, with 4 minute setae near posterior apex and 5 or 6 small pores medially. Anogenital fold with 3 or 4 minute setae at each corner with anterior margin, and each lateral margin with 1 seta anteriorly.

Margin. Outer margins of stigmatic clefts with distinct irregular protrusions. Sclerotized ridges present submarginally, shallow, parallel with margin or extending inwards. Marginal setae broadly fan-shaped, each fan-shaped seta wider than long, about 28–53 μm wide and 18–39 μm long; numbering about 189–283 setae anteriorly on head between anterior stigmatic clefts, and each side with 87–107 between stigmatic clefts and 177–230 along abdominal margin. Stigmatic clefts quite deep, each with a narrow entrance, a highly sclerotized inner margin and 10–16 (usually 11–14) elongate, parallel-sided, blunt stigmatic spines. Eyespots displaced some distance from margin, each situated in a socket 41–68 μm wide, each lens 21–37 μm in diameter.

Venter. Derm membranous only in medial area; rest of derm lightly to heavily sclerotized, with sclerotized plates forming a band submedially; with a cluster of plates just laterad to each antenna, a similar-sized cluster of plates just laterad to each mesothoracic leg, and a much longer band of plates on abdomen, extending from area laterad to each metacoxa to anal cleft (these plates larger and more distinct on older specimens)); sclerotized band on each side of thorax about 1–3 mm wide. Multilocular disc-pores abundant on either side of genital opening and on preceding segment only, each side with 61–104 on segment VII and 74–150 on segment VI. Spiracular disc-pores present between margin and each spiracle in a narrow band 1–5 pores wide, with 109–150 pores in each anterior band and 98–168 pores in each posterior band. Ventral microducts each 2–3 μm wide, densely present just posterior to and on either side of labium, along with several setae; also, sparsely present elsewhere. Ventral setae: a pair of long setae present medially on segment VII, each seta 68–90 μm long; and short to long setae frequently present on medial areas of abdominal segments VI–V, each 8–71 μm long; otherwise, setae short and very sparse; interantennal setae absent. Antennae reduced, each with 5–7 segments but occasionally with a pseudo-articulation in segment III; total length 231–350 μm. Clypeolabral shield 291–397 μm long. Spiracles: width of each anterior peritreme 99–112 μm and posterior peritreme 96–119 μm. Legs present but very small, each with 5 segments much reduced in length, each segment unclearly divided, claw denticles absent; claw digitules and tarsal digitules narrow; total length of prothoracic leg 167–206 μm, mesothoracic leg 115–243 μm and metathoracic leg 137–227 μm.

Comment. The adult female of D. bambusae sp. n. differs from all other known Discochiton species in having: (i) a much larger body; (ii) a ventral band of sclerotisations in submedial areas of body; (iii) many stigmatic setae in each stigmatic cleft; and (iv) many marginal setae. While the morphology of the new species agrees with most character-states of Discochiton , the adult female displays a greater number of marginal radial lines and more stigmatic spines than are found on other Discochiton species. This may be due to the large body size of D. bambusae , which is the largest species in the genus, reaching approximately 15 mm long. In addition, the legs of D. bambusae are much reduced (similar to those of D. paucipedis (Hodgson)) , whereas other species of Discochiton show only fully developed or completely reduced legs. Moreover, the sclerotized plate-like areas on the venter of D. bambusae , which extend in a submedial band from the antennae to the anal cleft, are unique and have not been recorded previously in other species of Discochiton ( Hodgson & Williams, 2018) .

Figures

FIGURE 1. Discochiton bambusae Choi & Lee sp. n. A, the host plant, Bambusa tulda; B, population of adult females on a culm of B. tulda; C, dorsal view of adult female in life; D, ventral view of adult female in life; E, first-instar nymph; F, group of first-instar nymphs with plant debris; G, mass of first-instar nymphs left on the host after detaching the adult female.

FIGURE 2. Discochiton bambusae Choi & Lee sp. n. A, slide-mounted adult female; B, stigmatic cleft and spines; C, anal plates; D, marginal setae; E, antenna; F, prothoracic leg; G, mesothoracic leg; H, metathoracic leg; I, long dorsal seta; J, short dorsal seta; K, Clear areas (CA1–4); L, clear areas and associated preopercular pores; M, sclerotized plates forming ventral band; N, submarginal sclerotized ridges. Scale lines for A = 5 mm; K= 1 mm; M = 0.5 mm; B, C, E, F, G, H, L = 100 μm; D = 50 μm; I, J, N = 10 μm.

FIGURE 3. Discochiton bambusae Choi & Lee sp. n., adult female.A, reticulations; B, marginal radial lines indicated by pores and setae; C, marginal seta; D, stigmatic cleft and spines, and protrusions on outer margins of stigmatic cleft; E, submarginal sclerotized ridges; F, dorsal setae; G, preopercular pore; H, clear areas surrounded by preopercular pores; I, dorsal pores with a ductule and an unsclerotized pale area; J, anal plates; K, multilocular disc-pore; L, sclerotized plates forming a band; M, metathoracic leg; N, mesothoracic leg; O, prothoracic leg; P, spiracular disc-pore; Q, antenna.

FIGURE 4. Discochiton bambusae Choi & Lee sp. n., first-instar nymph.A, stigmatic spines; B, anal plate (left), and anal ring and anal fold (right); C, marginal seta; D, dorsal microduct; E, tarsus and claw with digitules and setae; F, submarginal seta; G, ventral microduct; H, spiracular disc-pore.