Asaphococcus agninus Cox

Hodgson, Chris, 2012, Comparison of the morphology of the adult males of the rhizoecine, phenacoccine and pseudococcine mealybugs (Hemiptera: Sternorrhyncha: Coccoidea), with the recognition of the family Rhizoecidae Williams 3291, Zootaxa 3291 (1), pp. 1-79 : 69-71

Asaphococcus agninus Cox

( Fig. 26 )

Asaphococcus agninus Cox : Cox, 1987: 17.

Material studied: New Zealand, Hauraki Gulf, Matuora Is., on Pittosporum crassifolium (Pittosporaceae) , 19.i.2006, R.E. Gardner-Gee ( NZAC): 1/1ad ♂ (in fair to good condition but some legs missing) + some nymphs.

Mounted material. Apterous; very small, 559 µm long, 228 µm wide; rather pointed at both ends. Antennae short, 8 segmented, bases close together on anterior margin of head. Head with 2 pairs of simple eyes plus a pair of ocelli; sclerotised ridges on head much reduced. Mesothorax membranous. Body with few hair-like setae, each 10–15 µm long. Loculate pores, each 4–6 µm wide with 3–5 loculi, restricted to thorax. Small simple pores (ssp) present only on abdominal segment VIII; minute sclerotised pores absent. Legs short, apparently without campaniform pores on trochanter; each leg probably with 1 tibial spur; tarsal digitules (tdgt) capitate. Glandular pouch area without a pouch but with loculate pores associated with a group of setae.

Head. Approximately triangular, with no indications of a neck. Dorsal. Length about 65 µm, greatest width 75 µm. Midcranial ridge, median crest and postoccipital ridge absent; with 6 pairs of hs dorsal head setae (dhs) distributed along full length of head. Genae (g) not differentiated from rest of head but perhaps with 2 short hs genal setae (gs) just behind each dorsal simple eye. Dorsal simple eyes (dse) distinctly larger than ventral simple eyes (vse) (dse oval, widest about 21 µm, on margin slightly anterior to vse; vse apparently round, about 15–17 µm wide, about 45 µm apart). Ocelli present, each 10 µm wide. Dorsal preocular ridge (procr) absent. Ventral. Ventral midcranial ridge (vmcr) strong, extending about 35 µm posteriorly, and with a further area of lighter sclerotisation posteriorly; with distinct lateral arms (lmcr) anteriorly. Ocular sclerite (ocs) not apparently differentiated but with very faint reticulations around each simple eye; with 1 pair of ventral head setae (vhs) on anterior margin of head, 2 pairs along vmcr and a small pair laterally. Preocular ridge (procr) absent ventrally. Postocular ridge extending for a short distance along lateral margin of head to ocelli, which it partially surrounds; interocular ridge absent. Cranial apophysis and preoral ridge absent.

Antennae: 8 segmented; length about 165 µm (ratio of total body length to antennal length 1:0.3). Scape (scp) 18–22 µm long, 26 µm wide, with 4 hs. Pedicel (pdc) with a few concentric ridges on distal end; 25 µm long, 19– 20 µm wide; with 4 hs + 1 or 2 fs, but no campaniform pore detected. Segment III very narrow proximally; segments III–VIII all about 15–20 µm wide; all slightly longer than wide, with narrow intersegmental membranes; lengths of segments (µm): III & IV 15–18; V–VII 21–24, apical segment 25; fs distinct, each 11–15 µm long; hs only slightly longer than fs, longest hs up to 20 µm; approximate number of setae per segment: III 2 or 3 hs + 0 or 1 hs; IV 1 or 2 + 1 or 2 fs; V 4 fs + 5 hs; VI & VII 4 fs + 5 hs + 1 antennal bristle (ab), and VIII 5 ab + 6 hs; not constricted apically; without capitate setae.

Thorax. Prothorax. Without any constriction between pro- and mesothorax; pronotal ridge, pronotal sclerite and post-tergite absent. Propleural ridge (plr 1) strongly sclerotised and extending to head near postocular ridge (pocr). Setae few both dorsally and ventrally but with 1 or 2 lp laterally. Sternum (stn 1) unsclerotised but with sternal apophyses; with 1 lp in position of prosternal setae (st 1 s); anteprosternal setae and antemesospiracular setae absent.

Mesothorax: unsclerotised; dorsum with two very sparse transverse bands of hs; ventrally with a few setae laterad to each spiracle and a few setae (possibly postmesospiracular setae (pm 2 s)) between mesothoracic spiracle and mesocoxae. Mesothoracic spiracles (sp 2) small, width of peritreme about 12 µm; each with 1 lp. Furca small but normally developed.

Metathorax: dorsally with 2 pairs of short setae as on each abdominal segment. Ventral part of metapleural ridge (plr 3) short but well-sclerotised; without either a metepisternum (eps 3) or a precoxal ridge (pcr 3); metepimeron (epm 3) absent. Metathoracic spiracles (sp 3) small, width of peritreme about 13 µm, each with an associated lp. Metasternum (stn 3) unsclerotised, with few setae; metasternal apophyses well developed.

Wings and hamulohalteres (h) absent.

Legs: Metathoracic legs probably longest. Coxae (cx): I 40; II -; III 42 µm long; coxa III with 6 hs. Trochanter (tr) + femur (fm): I 65; II 66; III 76 µm long; trochanter III with 4 hs; no campaniform pores detected on any trochanter, apparently absent; lacking Y-shaped ridges distally; long trochanter seta differentiated, each about 36 µm long; femur III with 2 hs. Tibia (ti): I 31; II -; III 51 µm long; tibia III with 4 short setae; all tibia probably with 1 apical spur (tibs) but those on protibia more setose; length about 10 µm. Tarsi (ta) 1 segmented; length (µm): I 23; II -; III 33 (ratio of length of tibia III to length of tarsus III 1:0.65); tarsus III with 6 setae, all setose; tarsal spurs not differentiated; tarsal campaniform pore very small; tarsal digitules (tdgt) with small capitate apices and longer than length of claw. Claws (c) fairly short, rather broad basally, slightly curved, without a denticle; length: III 14 µm; claw digitules (cdt) setose and slightly longer than claw.

Abdomen: segments I–VIII: unsclerotised; caudal extension (ce) of segment VII absent; ce on VIII rounded. Setae present in a single sparse line around each segment, all short, each about 10–15 µm long; each segment with 4 dorsal abdominal setae (ads), 1 or 2 dorsal pleural setae (dpls), 1 or 2 ventral pleural seta (vpls) and 4 ventral abdominal setae (avs). Segment VIII with a pair of flat glandular pouches — or areas with 10–15 loculate pores — each with 4 long associated setae but these not actually amongst loculate pores; longest setae 75–85 µm long, shorter setae about 40 µm long; without ante-anal setae but with small simple pores near each glandular pouch. Sternite VIII without setae or pores; pleurite VIII with 1 short setae + 1 or 2 longer setae, each about 30–35 µm long.

Genital segment: penial sheath (ps) much narrower than width of abdominal segment VIII; longer than wide (55 µm long; 43 µm wide at base); exact structure hard to see but ps narrowing towards apex with a short fingerlike apical extension with sensoria (psp); with a broad slit-like opening ventrally through which aedeagus (aed) emerges. Anus not detected; dorsolaterally with 3 pairs of setae (each 8–12 µm long); ventrally with 2 pairs of shorter setae on margin of slit-like opening. Aedeagus hard to discern but perhaps broad, maybe 33 µm long; basal rod not located.

Comments. The adult male of Asaphococcus agninus is superficially very like the apterous adult males of Rhizoecidae , no doubt due to convergence. Nonetheless, the males of A. agninus still have: (i) ocelli; (ii) a distinctly sclerotised postocular ridge; (iii) a strong ventral midcranial ridge; (iv) a small group of loculate pores in the area of the glandular pouches, and (v) a basally narrow penial sheath — all character states not found in Rhizoecidae but characteristic of Pseudococcidae . Unfortunately, the position of the anus could not be seen. In addition to the above character states, the apterous male Saccharicoccus sacchari has (after Afifi, 1968): (i) a distinct postoccipital ridge; (ii) a small cranial apophysis; (iii) a slender tentorial bridge; (iv) pronotal sclerites often present; (v) post-tergites well developed; (vi) transverse ridge of prosternum distinct; (vii) proepisternum + cervical sclerite quite long, clearly reaching base of postocular ridge; (viii) most other segments with some weakly sclerotised tergites and sternites; (ix) ostioles; (x) a reasonably distinct pair of glandular pouches, each with 2 long setae and a shorter seta; (xi) ventral slit of penial sheath with a pair of penial sheath processes, each with a set of fine setae; and (xii) penial sheath only about half width of abdominal segment VIII. Similarly, the apterous male of Dysmicoccus jenniferae ( Williams, 1985) has most of these features and clearly keys out within the Pseudococcidae . Most of these features are unknown on apterous rhizoecine mealybugs. Miller and Polavarapu (1997) also described an apterous form of D. vaccinii but this form still retains the major box-like sclerites of the mesothorax and all the main head structures and actually keys out in the macropterous and brachypterous key for mealybugs above.

The possible absence of campaniform pores on the trochanter of A. agninus is intriguing — but none were shown by Afifi (1968) on the trochanter of the eriococcid Pseudochermes fraxini (Kaltenburg) . This latter species also has ocelli but no simple eyes.

Cox (1987) indicated that some specimens of A. agninus were collected from under the bark of its host plant ( Pittosporum sp. ), which might account for why the males are apterous. Hardy et al. (2008) placed Asaphococcus in the Pseudococcinae .

Figures

FIGURE 26. Asaphococcus agninus Cox. Adult male. Where C = loculate pore. For other labels, see under Materials and methods: conventions.