Pseudorhizoecus proximus Green

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 : 16-18

Pseudorhizoecus proximus Green

( Fig. 3 )

Pseudorhizoecus proximus Green ; Green, 1933: 55.

Material examined. Holotype and paratypes: Surinam, on the roots of coffee ( Rubiaceae ), no date, G. Bünzli ( BMNH): 3/ 3♂♂, mostly in good condition but all mounted sideways .

Mounted material: apterous. Small, total body length about 615–640 µm, greatest depth 430–470ìm; probably laterally flattened in life. Antennae 5 or 6 segmented, short, about 1/5th total body length, each segment rather broad and ring-like; flagellar segments with mainly hair-like setae (hs), fleshy setae (fs) very few; with a short apical spinose seta. Body densely covered in short, fine setose setae, each 8–10 µm long arranged in segmental bands; loculate pores (lp) each 3.5–4 µm wide, with mainly 4 loculi, frequent, mainly in rows along intersegmental membranes; simple pores not detected. Legs stout; tarsi (ta) 1 segmented; tarsal digitules (tdgt) absent; trochanter (tr) with 2 pairs of campaniform pores.

Head: apparently very short, with no obvious sclerotised ridges. Dorsally covered in numerous short, setose setae, plus a few loculate pores along posterior and ventral margins. Genae (g) and ocular sclerite (ocs) not differentiated and all eyes absent. Ventral epicranium unsclerotised; with about 4 setae between antennae, each about 15–17 µm long, plus 2 or 3 lp. Cranial apophysis absent; with an area of folded membranous derm just anterior to procoxae, which might represent mouthparts.

Antennae: 5 or 6 segmented (sometimes 5 on one side and a partial 6 on other); length about 130–155 µm long (ratio of total body length to antennal length 1:0.23). Scape (scp): 25–33 µm long, 50 µm wide, with many hs; positioned rather close together on anterior margin of head. Pedicel (pdc): length 13–17 µm, width 40–45 µm; with many hs + 1 or 2 campaniform pores. Segments III–V ( VI) narrowing towards antennal apex and all wider than long; lengths of segments (µm) III 20, IV 12–17, (V 12–15) and apical segment 43–45; each segment with many hs but segments II–IV (V) each with 2 fs and apical segment with 5–7 fs or antennal bristles (ab), latter up to 33–40 µm long. Hair-like setae (hs) all rather variable in length, longest up to perhaps 40 µm; apex with a short spine-like seta 6–8 µm long.

Thorax. Prothorax: without a neck; not obviously swollen laterally; all ridges, etc absent; setae all finely setose, abundant dorsally, but few or absent ventrally. Propleural ridge (plr 1) well developed but rather short, not nearly reaching head. Sternum (stn 1) unsclerotised but possibly with a few prosternal setae (stn 1 s) and probably 1– 3 lp; other ventral setae apparently randomly arranged.

Mesothorax: unsclerotised. Dorsum with 2 broad, dense bands of fine setose hs; ventrally with a few setae medially between mesocoxae (possibly postmesospiracular setae (pm 2 s)); loculate pores in intersegmental membranes dorsally, bands combining ventrally to form a single transverse band. Mesopleural ridge (plr 2) well developed but short. Mesothoracic spiracle (sp 2) rather large, with a large U-shaped sclerotised ridge along ventral margin: width across U-shaped ridge about 33 µm, width of peritreme about 20 µm, length of spiracle plus muscle plate transversely about 53–55 µm. Furca not detected.

Metathorax: dorsally with a single broad band of fine setose setae, and with a line of loculate pores (lp) along intersegmental membrane, becoming a sparse transverse band ventrally. Dorsal part of metapleural ridge absent; ventral part short but well-sclerotised; metepisternum absent; metapleural ridge (plr 3) without either a metaprecoxal ridge or an additional short ridge extending ventrally from near coxal articulation. Metathoracic spiracle (sp 3) similar in size and shape to those on mesothorax. Metasternum (stn 3) unsclerotised and with a few setae more or less between metacoxae.

Wings and hamulohalteres (h) absent.

Legs: stout and well developed; metathoracic legs slightly longest. Coxae (cx): I 82–90; II 85–90; III 80–90 µm long; each coxa III with about 12 hs; long setae on each coxa not differentiated, but about 20 µm long. Trochanter (tr) + femur (fm): I 118–140; II 120–145; III 132–158 µm long; trochanter III with about 10 hs; each trochanter with 2 pairs of roundly oval sensoria, and with strong sclerotised ridges for articulation with femur; Yshaped ridges absent; long trochanter seta not differentiated but seta in this position about 25 µm long; femur III with 25–30 hs. Tibia (ti): I 78–94; II 70–90; III 95–108 µm long; tibia III with many setae, mainly hs, becoming spur-like ventrally towards distal end; tibial spurs (tibs): with 4 on each metatibia, only slightly stouter than more proximal spurs, about 20–25 µm long. Tarsi (ta) 1 segmented; length (µm): I 37–44; II 37–40; III 44–45 (ratio of length of tibia III to length of tarsus III 1:0.45); tarsus III with 15 or 16 setae, mainly spur-like; tarsal spurs not differentiated; tarsal campaniform pore present; tarsal digitules (tdgt) absent. Claws (c) quite long, slightly curved, without a denticle; length: III 30–31 µm; claw digitules (cdt) short and setose.

Abdomen: segments I–VIII: tergites (at) and sternites (as) becoming sclerotised on more posterior segments. Caudal extensions (ce) of segments VII and VIII absent. Loculate pores (lp) in transverse rows along intersegmental membranes, becoming less frequent posteriorly and absent on segment VIII; setae all short and finely setose in broad bands as on thorax and head, all about 8–10 µm long; similar setae present ventrally in sparse transverse bands, least abundant posteriorly. Segment VIII without long setae.

Genital segment: penial sheath (ps) on available material pointing ventrally and probably forming a pointed cone; dorsally ps with a triangular sclerite with about 30 short, setose setae similar to those on dorsum of abdomen; ventrally possibly more membranous, with a few setae and with a slit through which aedeagus emerges. Length of ps about 140–170 µm, greatest width uncertain but perhaps 150 µm. Anus (a) present at anterior end, oval, widest transversely, about 35 µm wide. Aedeagus (aed) strongly curved ventrally, about 95–100 µm long, with a sharp apex and rather parallel margins; anteriorly and internally, aedeagus articulates with base of a strongly sclerotised, probably U-shaped, structure whose homologies uncertain. Penial sheath possibly without sensilla on apex.

Comment. The adult male of Ps. proximus is clearly structurally similar to that of Capitisetella migrans (Green) . For further discussion see under that species above.

Figures

FIGURE 3. Pseudorhizoecus proximus Green. Adult male. Where A = hair-like seta; C = loculate pore; K = distal end of metathoracic leg and N = side view od posterior end of abdomen. For other labels, see under Materials and methods: conventions.