Akermes scrobiculatus (Maskell)

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 : 225-227

Akermes scrobiculatus (Maskell) ( Fig. 88 )

Lecanium scrobiculatum Maskell 1893, 221 . Type data: Australia, New South Wales, Whitton, on Acacia sp. Syntypes, both sexes, Type depositories: NZAC, BMNH, USNM.

Akermes scrobiculatus Fernald 1903 , 178. Change of combination.

Material examined: Australia, A.C.T., Canberra, upper end of Botanic Gardens, on stems of Acacia sp. ( Fabaceae ), 25 Feb. 1998, C.J. Hodgson ( ANIC): 4/4ad ♂♂ (good-fair).

Mounted material. Moderate size, with rather short antennae, each about half total body length; head with two pairs simple eyes; head and rest of body with very few setae, all hair-like (hs); fleshy setae (fs) on appendages usually easy to separable from hs; procoxae each with two stout bristles; trochanterofemur articulation obscure or absent. Abdominal caudal extensions on VIII rounded, each with a dorsal, lightly sclerotised, protuberance (cicatrix); glandular pouches absent. Total body length 1.4–1.48 mm, width across triangular plates (tp) about 350 μm. Wings slightly shorter than total body length and about half as wide as long.

Head. Roughly diamond-shaped; length 225–230 μm; width across genae about 230 μm. Setae almost absent. Median crest (mc) well developed, with vaguely reticulate striations; postoccipital ridge (por) absent; with a total of 2 pairs of hs dorsal head setae (dhs). Mid-cranial ridge absent dorsally; ventrally, mid-cranial ridge (vmcr) narrow but well-defined, extending posteriorly as far as ocular sclerite; without a reticulated margin; ventral mid-cranial ridge setae (vmcrs) absent. Preocular ridge (procr) quite long dorsally; ventrally extending medially and fusing with posterior end of vmcr. Genae (g) large and membranous, without genal setae (gs) and without polygonal reticulations but with a few striations. Eyes: two pairs of round simple eyes, 1 pair dorsally (dse) and 1 pair ventrally (vse), subequal in size, each 40–45 μm wide. Ocelli absent or not detected. Ocular sclerite (ocs) sclerotised and heavily polygonally reticulated, each reticulation without inner microridges. Postocular ridge (pocr) extending medially almost to median crest. Dorsal ocular setae absent although a small hs seta present between postocular ridge (pocr) and median crest (mc). Ventral head setae restricted to 0 or 1 pair between ventral simple eyes (vse). Tentorial bridge (tb) well developed. Cranial apophysis (ca) possibly absent.

Antennae: 10 segmented and filiform. Scape (scp): 37–45 μm long, 45–50 μm wide, with 3 hs. Pedicel (pdc): 40–45 μm long, 50–55 μm wide, with a few transverse microridges, with 2 or 3 hs on ventral surface; campaniform pore present. Segments III–X each 18–30 μm wide; length of fs 17–24 μm (occasionally down to 8 μm): lengths (μm): III 60–65; IV 90–95; V 93–98; VI 95–100; VII 85–90; VIII 65–70; IX 73–78; X 7–75; approximate number of setae per segment: III 6 or 7 fs + 0 hs; IV 10–16 fs + 0 hs; V–VII 16–25 fs + 0 hs; VIII & IX 13–17 + 1 antennal bristle (ab) (each very short, only about 12 μm long); X 16–19 fs, of which 5 probably ab but not differentiated + 3 capitate setae (caps).

Thorax. Prothorax: pronotal ridge (prnr) well developed, apparently fused medially; pronotal sclerite (prn) narrow or absent; without lateral pronotal setae (1 present on one side of one specimen). Post-tergites (pt) not detected; without post-tergital setae. Median pronotal and other dorsal and pleural setae absent. Proepisternum + cervical sclerite (pepcv) well developed. Sternum (stn 1) with a strong transverse ridge; median ridge absent; sternite with shallow transverse ridges; prosternal setae (stn 1 s), anteprosternal setae (astn 1 s) and antemesospiracular setae (asp 2 s) absent.

Mesothorax: probably convex in life; prescutum (prsc) slightly wider than long, 120–130 μm long, 160–170 μm wide; sclerotised, with obscure nodulations; prescutal setae (prscs) absent; prescutal ridge (pscr) and prescutal suture (pscs) well developed. Scutum (sct): median membranous area (sma) probably 65–70 μm long, 170–180 μm wide, with 0 or 1 pair of hs scutal setae (scts); lateral margins of membranous area bounded by sclerotised ridges; scutum with a few polygonal nodulations laterad to scutellum. Scutellum (scl) 53–66 μm long, 173–180 μm wide; with a moderately large foramen; scutellar setae absent. Mesepisternum (eps 2) not nodulated. Postalare (pa) striated at anterior end; without postalare setae. Basisternum (stn 2) large, 155–170 μm long, 240–260 μm wide; median ridge (mdr) well developed and complete; stn 2 bounded anteriorly by strong marginal ridges (mr) and posteriorly by strong precoxal ridges (pcr 2); without basisternal setae (stn 2 s); lateropleurite (lpl) either without an extension from marginal ridge or this short; furca (f) well developed and extending anteriorly to a point anterior to where marginal ridge and precoxal ridges meet laterally. Subepisternal ridge (ser) well developed. Mesothoracic spiracle (sp 2): width of peritreme 37–39 μm; postmesospiracular setae absent. Antemetaspiracular setae absent. Mesopostnotum (pn 2) normally developed. Tegula (teg) without tegular setae (tegs).

Metathorax: metapostnotum (pn 3) small or absent; metatergal setae: 1 pair hs. Dorsospiracular setae absent. Dorsal and ventral part of metapleural ridge (plr 3) well developed; metepisternum (eps 3) lightly sclerotised, but without postmetaspiracular setae (pms); metepimeron (epm 3) short, without setae. Metathoracic spiracle (sp 3): width of peritreme 38 μm. Metasternum (stn 3) membranous and not reticulated. Anterior metasternal (amss) and posterior metasternal setae (pmss) absent.

Wings: hyaline; of moderate length and width, 1.13–1.18 mm long, 0.58 mm wide (ratio of length to width 1:0.5). Alar setae (als) and sensoria (sens) absent. Hamulohalteres each 105–110 μm long, 33 μm wide; each with one hamulus, length about 58 μm.

Legs: metathoracic legs marginally longest; all segments with few setae, mainly fs. Coxae (cx): length (μm): I 107, II 100, III 100–105; each procoxa with 2 stout coxal bristles (cb), each 50–65 μm long; meso- and metacoxae each with a long coxal seta about 55–60 μm long; metacoxa with 5–7 fs + 9 hs. Trochanterofemur (tfm) with seg- mentation indistinct; length (μm): I 210–225; II 195–200, III 200–210; each trochanter (tr) with a line of small cam- paniform sensilla; long trochanter seta short, about 50 μm long; metatrochanter with 1–3 fs + 2 hs; each metafemur with 4–7 fs + 3 hs. Tibia (ti) long: length (μm) I 235–260; II 255–270; III 270–290; metatibia with 30–35 fs + 13 hs, latter becoming spur-like distally on ventral margin; apical spur (tibs) weak and often absent; when present, each 27–30 μm long. Tarsi (ta) one segmented: lengths (μm): I, II & III 100–110; metatarsi with 5–7 fs + 6 or 7 hs; tarsal campaniform pore absent; distal tarsal spur (tars) very variable, from absent to setose (when about 35 μm long) to spinose, when 25–28 μm long; tarsal digitules (tdt) subequal to claw. Claws (c) short, each about 27 μm long, subequal to or longer than width of tarsi, without a denticle (cd); claw digitules (cdt) with small capitate apices and slightly longer than claw.

Abdomen. Segments I–VIII: tergites (at) represented by light sclerotisations on segments IV–VIII and sometimes on III and II; sternites (as) present as a light sclerotisation on all segments, but that on VIII more distinct. Caudal extensions of segment VII (ce VII) absent; those on segment VIII (ce VIII) rounded, each with a dorsal, lightly sclerotised protuberance (possibly a cicatrix), with 4 or 5 small pleural hs. Dorsal abdominal setae (ads) few, with a total of 1–4 per segment; without ante-anal setae (aas) on VIII. Pleural setae: all hs; dorsal pleural setae (dpls): I–VI each with 0; V & VI each with 1; VII 1 or 2; ventral pleural setae (vpls): I–III each with 0; IV & V each with 1 or 2; VI & VII each with 1 or 2. Ventral abdominal setae all hs, with 0 on segment VIII, and a total of 4–8 on IV–VII; none on II or III. Glandular pouches (gp) absent.

Genital segments. Segment IX and style intimately fused. Penial sheath (ps) typical of male Coccidae : fairly long, gradually narrowing to a blunt apex; about 1/4th total body length (ratio of total body length to penial sheath length 1:0.26); length 285–310 μm; width at base 85–90 μm; with strongly sclerotised margins. Basal rod (bra) short, 28–50 μm long, anterior end not nearly reaching basal membranous area (bma) (40–45 μm from bma). Ae- deagus (aed) quite long, 132–165 μm long, gradually narrowing towards apex; latter nowhere near end of style. Apex of style with a cluster of small sensillae (gtp) and with about 8–12 minute setae (gts) along each margin.

Comment. For comments on this species and A. pinguis , see under that species below.

Figures

FIGURE 88. Akermes scrobiculatus (Maskell). Macropterous male. (Coccidae). Where R=dermal reticulations on ocular sclerite.