Capitisetella migrans (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 : 11-13

Capitisetella migrans (Green)

( Fig. 1 )

Pseudorhizoecus migrans Green, 1933: 56

Capitisetella migrans (Green) : Hambleton, 1977: 40.

Material examined. Lectotype: Surinam, on the roots of coffee ( Rubiaceae ), no date, G. Bünzli ( BMNH): 1/ 1♂ lectotype plus paralectotype nymph (+ parasitoid), in good condition but mounted sideways.

Mounted material: total body length about 700 µm, greatest depth 475 µm; probably somewhat laterally flattened in life. Body and appendages sparsely covered in large capitate setae (cs), each 20–35 µm long, arranged in segmental bands; each seta generally with a fairly broad area of sclerotisation surrounding basal socket. Antennae 3 segmented, short, about 1/4th total body length, each segment rather broad; apical segment with many cs, a few setose setae or antennal bristles (ab), and an apical spine-like seta. Loculate pores (lp) each 6–7 µm wide, with mainly 3 or 4 loculi, frequent, mainly in segmental bands intermingling with cs; simple pores not detected.

Head: apparently very short. Dorsally covered in cs, plus a few lp. Epicranium unsclerotised; ventrally without setae between antennae but with a few lp.

Antennae: 3 segmented; length about 190–210 µm long (ratio of total body length to antennal length 1:0.29). Scape (scp): 44–47 µm long, 58–60 µm wide, with 4 cs. Pedicel (pdc): length 30–35 µm, width 50–52 µm; with 5 cs + 1 campaniform pore; segment III long, length 130–135 µm; narrowing to a blunt apex; with about 50 cs (each 20–45 µm long), a few setose setae, each 23–33 µm long, plus about 14–16 ab, each 25–43 µm long, those near apex longest. Apex with a spine-like seta about 30 µm long.

Thorax. Prothorax: setae all cs, similar to those elsewhere, in a sparse band dorsally, but with only 1 or 2 ventrally; lp sparse throughout. With a squarish sclerotisation in position of tentorium anterior to procoxae, 53 µm long and about 70 µm wide. Sternum (stn 1) with about 3 lp.

Mesothorax: unsclerotised. Dorsum with a broad bands of cs and lp; ventrally with a few setae medially between mesocoxae. 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 14 µm, length of spiracle plus muscle plate about 56 µm. Furca (f) well developed.

Metathorax: dorsally with a single broad band of cs plus lp. Metathoracic spiracles (sp 3) similar to those on mesothorax; width across U-shaped ridge about 31–33 µm, width of peritreme about 13–17 µm, length of spiracle plus muscle plate transversely about 46 µm. Metasternum (stn 3) with a few cs and lp medially just anterior to metacoxae. Furca (f) well developed.

Wings and hamulohalteres (h) absent.

Legs: prothoracic legs longest. Coxae (cx): I 107; II 89; III 95 µm long; each coxa III with about 5 cs; long seta on each coxa not differentiated, but seta in this position about 15–18 µm long. Trochanter (tr) + femur (fm): I 160–165; II 158; III 153–158 µm long; trochanter III with about 6 cs; long trochanter seta not differentiated but seta in this position about 23–25 µm long; femur III with about 19 or 20 cs. Tibia (ti): I 85; II 83; III 83 µm long; tibia III with about 16 cs, none spur-like; tibial spurs (tibs) absent. Tarsi (ta) 1 segmented; length (µm): I 66; II 60; III 60 (ratio of length of tibia III to length of tarsus III 1:0.72); tarsus III with about 13 cs, none spur-like. Claws (c) quite long, slightly curved; length: III 33 µm.

Abdomen: setae all cs, similar to those elsewhere; more or less in a transverse line across each segment; ventrally with similar setae but sparser, possibly absent from segment VIII; loculate pores (lp) more or less in a line with cs, becoming less frequent posteriorly and absent from segments VII and VIII.

Genital segment: penial sheath (ps) on available specimen pointing ventrally and probably forming a pointed cone; length 140 µm, width uncertain; ps dorsally elongate, with about 6 cs similar to those elsewhere; ventrally possibly more membranous, with perhaps 5 cs. Anus (a) oval, situated at anterior end of ps, widest transversely, possibly about 25 µm wide. Aedeagus (aed) strongly curved ventrally, about 130 µm long, with a sharp apex and rather parallel margins; anteriorly and internally, aedeagus fused to a basal rod which articulates with a strongly sclerotised, U-shaped structure whose homologies uncertain; U-shaped structure about 155 µm long from anterior margin to anus. Penial sheath with a few sensilla (psp) along margin near apex.

Comment. The adult male of C. migrans is clearly structurally similar to that of Pseudorhizoecus proximus (described below), only really differing in: (i) the type of dermal setae (capitate on C. migrans , small setose on Ps. proximus ), (ii) the presence/absence of tibial spurs (absent on C. migrans , present on Ps. proximus ), (iii) the distribution of the loculate pores (segmental amongst the setae on C. migrans and intersegmental on Ps. proximus ), and (iv) the number of antennal segments (3 on C. migrans and 5 or 6 on Ps. proximus ). The adult females of these two species are rather similar: capitate setae on C. migrans , small setose on Ps. proximus ; 3 antennal segments on C. migrans and 5 on Ps. proximus ; differently structured trilocular pores; and an anal ring with 6 setae and a few obscure pores on C. migrans but that of Ps. proximus with 2–5 short seta and with>20 small protuberances. Whether these differences are sufficient to justify keeping the two species in separate genera is unclear. Both Capitisetella and Pseudorhizoecus are monotypic and the discovery of further species in either genus might make their status clear.

Figures

FIGURE 1. Capitisella migrans (Green). Adult male. Where A = capitate seta; B = fleshy seta; C = loculate pores, and N = side view of posterior end of abdomen. For other labels, see under Materials and methods: conventions.