Hsuia cheni Borchsenius

Hodgson, Chris, 2020, A review of neococcid scale insects (Hemiptera: Sternorrhyncha: Coccomorpha) based on the morphology of the adult males, Zootaxa 4765 (1), pp. 1-264 : 190-193

Hsuia cheni Borchsenius ( Fig. 74 )

Hsuia cheni Borchsenius 1960 , 167. Type data: China, Sichuan, Guansyan district, on leaves of bamboo. Syntypes, female, by original designation. Type depository: ZIAS, Russia.

Material examined. China, Beipei, on bamboo ( Poaceae ), 29.xi.1954, N. Shutova (Leningrad collection no. 194– 57) ( BMNH): 1/4ad ♂♂ (fair) (Note: Beipei is probably now a district within Chongqing).

Mounted material: very small, total body length 0.85–0.88 mm; robust; antennae a little more than half total body length, with long setae on segments VII and X; body with very few setae, fleshy setae (fs) difficult to differentiate from hair-like setae (hs); length of shorter setae (fs) on antennae more than width of antennal segments. Wings about 4/5ths total body length and rather narrow.

Head: appearing oval to rather triangular in dorsal view on mounted specimens; width across genae 178–200 μm. Median crest (mc) very broad posterior to antennae, reticulated, each reticulation without additional inner mi- croridges, reticulations extending laterally; posteriorly with two sclerites lying diagonally to mid-line, representing a postoccipital ridge (por); with 0 or 1 pair of dorsal head setae (dhs). Mid-cranial ridge absent dorsally; ventral ridge (vmcr) well developed but moderately short, extending posteriorly only to about half way to anterior margin of ventral eyes; with well-developed lateral arms (lmcr); with a narrow, reticulated border anteriorly, broadening posteriorly where it fuses with ocular sclerite; without ventral mid-cranial ridge setae (vmcrs). Genae (g) without polygonal reticulations; genal setae (gs) absent. Eyes: with two pairs of round simple eyes; dorsal eyes (dse) marginally smaller than ventral eyes (vse): dorsal eyes 25–27 μm wide; ventral eyes 30–33 μm wide. Ocelli (o) absent. Ocular sclerite (ocs) sclerotised and polygonally reticulated throughout, each reticulation rather small, without inner microridges but each reticulation with many small spots. Preocular ridge (procr): ventral arm extremely short near lateral margin of each scape; dorsal arm extending posteriorly around inner margin of dorsal simple eye, fading posterior to dorsal eye and not fusing with postocular sclerite. Postocular ridge (pocr) strongly developed, extending dorsally just posterior to dorsal eyes and then posteriorly to level with postoccipital ridge. Dorsal ocular setae (docs) absent. Ventral head setae (vhs): with 5–7 on each side, plus 2 or 3 pairs between ventral eyes; vhs extending laterally almost to dorsal eyes; without setae posterior to ventral eyes. Preoral ridge (pror) possibly absent or poorly developed. Cranial apophysis (ca) narrow and elongate, broadening slightly at anterior end, extending anteriorly almost to ventral eyes; about 42 μm long.

Antennae: 10-segmented and filiform, each 482–515 μm long (ratio of total body length to antennal length 1:0.57); setae all rather similar, not easily differentiated into fs and hs but with an extremely long seta (possibly ab) on segments VII and X. Scape (scp): 27 μm long, 33–35 μm wide, with 9 or 10 setae. Pedicel (pdc): length 25–27 μm, width 25–27 μm; with a few concentric reticulations; with 7–10 setae. Segments III–X each 10–17 μm wide: shorter setae each 26–28 μm long, long seta on segment VII 56–67 μm long and that on apical segment 46–50 μm long; lengths of segments (μm): III 53–60; IV 65–69; V 54–60; VI 56–60; VII 58–60; VIII 48–55 and IX 51–53; approximate number of setae per segment: III 9–15 shorter setae (sensilla basiconica not noted); IV 14–16 shorter setae; V 10–15 shorter setae; VI 14–16 shorter setae; VII 11–16 shorter setae + 1 long seta; VIII 9–15 shorter setae; IX 15 shorter setae (bristles, if present, undifferentiated). Segment X 64–70 μm long; not constricted apically; with 3 capitate setae (caps), 11–15 shorter setae + 1 long seta + 1 long bristle; sensilla basiconica (sb) not noted.

Thorax. Prothorax: pronotal ridge (prnr) well-developed, each arm broadening medially on dorsum but not fusing medially; with a broad, striated, lateral pronotal sclerite (prn), without lateral pronotal (lpns) setae. Medial pronotal setae, post-tergites and post-tergital setae apparently absent. Sternum (stn 1) not sclerotised and without ridges or reticulations laterad to median ridge; transverse ridge weak, with transverse striations; median ridge strongly sclerotised anteriorly and quite long, extending anteriorly to between procoxae (length about 50 μm long) but becoming weakly sclerotised posteriorly; without prosternal setae (stn 1 s). Anteprosternal (astn 1 s) and antemesospiracular setae (am 2 s) absent.

Mesothorax: prescutum (prsc) 48–52 μm long, 94–112 μm wide; sclerotised, with striations, occasionally ap- pearing nodulated; prescutal ridges (pscr) and prescutal suture (pscs) well developed. Scutum (sct): median membranous area 91–116 μm wide, 43 μm long, bounded laterally by strongly sclerotised margins; scutal setae (scts) absent; surface medially not reticulated; lateral margins sclerotised and slightly reticulated, particularly anteriorly laterad to prescutum; reticulations weak of absent laterad to scutellum. Scutellum (scl) 111–133 μm wide, 50–55 μm long; with a large foramen; without scutellar setae (scls). Basisternum (stn 2) 144–177 μm wide, 86–90 μm long; with a strong median ridge (mdr); bounded anteriorly by a moderately strong marginal ridge (mr) and posteriorly by a strong precoxal ridge (pcr 2); without basisternal setae (stn 2 s); lateropleurite (lpl) reasonably broad, rather more sclerotised than is usual on male Coccoidea , with a weak extension from marginal ridge anteriorly; furca (f) well developed, broad basally, arms more or less parallel; extending anteriorly about 2/3rds to marginal ridge. Mesopostnotum (pn 2) and postnotal apophysis (pna) well developed; area bounded anteriorly by scutellum and laterally and posteriorly by mesopostnotum weakly reticulated. Mesepisternum (eps 2) slightly striated; subepisternal ridge (ser) well developed. Postalare (pa) distinctly reticulated anteriorly; without postalare setae (pas). Mesothoracic spiracle (sp 2): peritreme 15–17 μm wide. Postmesospiracular setae (pm 2 s) absent. Tegula (teg) weakly developed, with 4 or 5 tegular setae (tegs) on each side.

Metathorax: without metatergal setae (mts). Dorsospiracular setae (dss) absent. Dorsal part of metapleural ridge (plr 3) absent; ventral part of metapleural ridge well developed; metepisternum (eps 3) unsclerotised, without postmetaspiracular setae (eps 3 s). Metepimeron (epm 3) sclerotised but without setae. Antemetaspiracular setae (am 3 s) absent. Metathoracic spiracle (sp 3): width of peritreme 17 μm. Metasternum (stn 3) lightly sclerotised. Anterior metasternal setae (amss) and posterior metasternal setae (pmss) absent.

Wings: hyaline, 685–700 μm long, 301–305 μm wide (ratio of length to width 1:0.44; ratio of total body length to wing length 1:0.80); alar lobe (al) and alar setae (als) absent; wing venation normal. Hamulohalteres absent.

Legs: metathoracic legs possibly marginally longest. Setae difficult to separate into fs & hs. Coxae (cx): I 66–71; II 70–75; III 70–75 μm long; coxa III with 15–17 setae; long apical seta on each coxa not differentiated. Trochanter (tr) + femur (fm): I 154–174; II 161–174; III 170–174 μm long; trochanter III with 15 or 16 setae; long trochanter seta not differentiated; rather bulbous distally, much wider than base of femur, and also significantly broadened along ring of campaniform pores; femur III with 24–32 setae. Tibia (ti): I 120–128; II 116–120; III 136–141 μm; tibia III with a total of 36–40 setae, becoming spur-like on distal third; without apical spurs (tibs). Tarsi (ta): I 120–128; II 136–141; III 149–156 μm long (ratio of length of tibia III to tarsus III 1:1.11); tarsus III with 95–100 setae, some spur-like, most frequent distally; tarsal spurs undifferentiated; tarsal campaniform pore present; tarsal digitules (tdt) fine, with small apical knobs, significantly shorter than claw. Claws (c) quite long and thin, rather longer than width of tarsi, slightly curved, without a denticle, not held at right-angles to tarsus; length: III 21–23 μm; claw digitules (cdt) fine, with small apical knobs, slightly longer than claw.

Abdomen: segments I–VII: tergites (at) all lightly reticulated medially; sternites (as) of all segments lightly sclerotised. Caudal extension (ce) of segment VII absent. Dorsal setae (ads) absent. Pleural setae: dorsopleural setae (dps): II–VII each with 1 hs on each side; ventropleural setae (vps) absent. Ventral setae (avs) (totals): II–V setae absent; VI & VII each with 1 pair hs.

Segment VIII: semi-cylindrical, more or less forming anterior part of penial sheath; tergite quite strongly sclerotised laterally but membranous medially, without ads or avs setae; sternite sclerotised, with 1 pair of avs setae; caudal extension (ce) absent or poorly developed posteriorly and ill-defined; with 3 or 4 pleural setae on each side, one significantly longer, 26–33 μm long. Glandular pouches (gp) absent.

Genital segments: segment IX and style fused; length of penial sheath from anterior margin of segment IX 88–107 μm (ratio of total body length to penial sheath length 1:0.11) (length with segment VIII 132-150 μm); width at anterior end of segment IX 43–47 μm. Segment IX quite broad anteriorly, closely attached to abdominal segment VIII, sides parallel; anus present at anterior end of segment IX. Style quite broad anteriorly and then gradually narrowing to a fine apex; sclerotised; anteriorly with 2 or 3 pairs of long setae ventrally laterad to basal rod (each 34–37 μm long) and with 1 or 2 pairs smaller setae dorsally (each 2–9 μm long); posteriorly with 3 or 4 pairs of long setae laterally, each about 25 μm long; without a cluster of small sensilla near apex. Basal membranous area (bma) appar- ently present anterior to basal rod; basal rod (bra) extending anteriorly almost to segment VIII, length 13–30 μm, not extending down aedeagus. Aedeagus (aed) long, bent ventrally and tapering to a sharp point, 75–83 μm long (ratio of aedeagus length to basal rod length 1:0.25); significantly longer than apex of penial sheath.

Comment. The adult males of H. cheni belong to the group that have exceptionally long setae on the antennae. It differs from all known species except Grammococcus spp. (which lack long setae on the antennae) in having a rather short penial sheath, only about twice as long as basal width of abdominal segment VIII.

General comment. Apart from (i) the long setae on the antennae, and (ii) the reticulation on the membranous part of the scutum, the species described here are extremely similar to the adult male of A. proteae ( Giliomee & Munting 1968) . Other less obvious differences between these species and A. proteae are (character-states on A. proteae in brackets): (i) only one pair of oblique sclerotisation in position of post-occipital ridge (two pairs); (ii) ocular sclerite distinctly reticulated (weakly striated); (iii) each apical antennal segment with only 3 capitate setae (each with 4 capitate setae, as also on A. petrophilae ); (v) prescutum, scutum and scutellum showing some reticulations (not reticulated); (vi) median ridge of basisternum complete (incomplete), and (vii) tergite of abdominal segment VIII with some sclerotisation (unsclerotised). The adult male Bambusaspis transversa is also very similar to the males decribed here, differing mainly in the absence of long setae on the penial sheath.

The males of Grammococcus adetocorymbus and G. corymbus are said to be very similar to each other ( Miller & Lambdin 1978). Their basic structure is very similar to that of the Asterolecanium species diagnosed above, sharing most characters-states with either one or the other species. However, they differ markedly in the structure of the penial sheath which is either about as wide as long or significantly wider than long. G. adetocorymbus also differs from the above species in (i) lacking an oblique postoccipital ridge; (ii) having 9-segmented antennae (shared with A. alba and A. petrophilae ) (iii) quite a strong transverse ridge to prosternum, at least medially, and (iv) the basal rod appears to extend entire length of aedeagus. Apart from the shape of the penial sheath and the 9-segmented antennae, G. adetocorymbus perhaps resembles A. delicatum most in having strong reticulations on the ocular sclerite, prescutum, lateral margins of scutum and in the area bounded by the scutellum and mesopostnotum.

Russell (1941) briefly described the male of A. ungulatum Russell. From the few details she provides, it would appear to be very similar to the species discussed above (10-segmented antennae; postocular ridge touching dorsal simple eyes; ventral head setae in broad group above ventral simple eyes; probably no ocelli; two oblique postoccipital ridges; scutellum with a foramen; absence of hamulohalteres; claws long and thin, without a denticle; absence of tibial spurs; no dorsal abdominal setae; single pairs of pleural setae per abdominal segment; long pleural setae on segment VIII, and long penial sheath, broadly attached to abdominal segment VIII).

Figures

FIGURE 74. Hsuia cheni Borchsenius. Macropterous male. (Asterolecaniidae). Where A=cranial apophysis and R=dermal reticulations on ocular sclerite.