Rhizoecus kazachstanus Matesova

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 : 29-32

Rhizoecus kazachstanus Matesova

( Fig. 8 )

Rhizoecus kazachstanus Matesova, 1980: 110 .

Material examined. Hungary, Csobánc , collected by DVAC, 6.v.2003, B. Kiss ( BMNH): 1/ 4♂♂ in fair to good condition .

Mounted material: apterous; very small, total body length about 488–615 µm, greatest width 215–245 µm; antennae 10 segmented, about half total body length; most flagellar segments broadening distally, with hair-like (hs) and fleshy setae (fs); fs reasonably easily separable from hs but apparently restricted to apical 6 segments; body with rather few setae, all hs and short, mainly 7–10 µm long; loculate pores (lp) each 5–7 µm wide with 3–5 loculi, absent from head but present ventrally on thorax and on both surfaces of abdomen; simple pores absent. Trochanter + femur with a Y-shaped articulation; trochanter (tr) with 2 pairs of campaniform pores; tarsi (ta) clearly 2 segmented.

Head: greatest width perhaps 100 µm. Dorsal epicranium only lightly sclerotised; with about 8 pairs of hs dorsal head setae (dhs) distributed along full length of head, each about 8–10 µm long. With about 3 genal setae (gs) posterior to each dorsal simple eye (dse). Simple eyes (se) subequal in size, each about 17–22 µm wide. Ocular sclerite (ocs) slightly differentiated. Ventral epicranium also barely sclerotised, without any sign of a ventral midcranial ridge or lateral arms of midcranial ridge; with 4 or 5 pairs of ventral midcranial ridge setae (vmcrs), each about 10–14 µm long. Preocular ridge (procr) absent dorsally but represented ventrally by thin ridges which extend medially past vse.

Antennae: 10 segmented; length about 310 µm long (ratio of total body length to antennal length 1:0.56). Scape (scp): 33–35 µm long, 28–33 µm wide, with 3 or 4 hs. Pedicel (pdc): length 34–36 µm, width 26–33 µm; with 4 hs + a small campaniform pore. Segments III–VIII all about 21–28 µm wide (greatest distally); all distinctly longer than wide, with narrow intersegmental membranes; lengths of segments (µm) III 33; IV 21–23; V–VIII 26– 33; IX 33–35, and X 46–48; fs each about 18–22 µm long; hs rather variable but longest up to 33 µm; approximate number of setae per segment: III & IV 4 or 5 hs; V–VII 4 or 5 fs + 4 or 5 hs; VIII 7 fs + 3 or 4 hs; IX 5 fs, 3 or 4 hs + 1 antennal bristle (ab), and X 6 or 7 fs, 2 or 3 hs + 3 ab.

Thorax. Prothorax: not obviously swollen laterally; setae rather few both dorsally and ventrally and apparently randomly distributed. Sternum (stn 1) with a loculate pore (lp) medially and with 1 pair of prosternal setae (stn 1 s); anteprosternal setae (astn 1 s) absent but with a lp in this position; antemesospiracular setae (am 2 s): with 1 or 2 setae in this position, plus a lp laterally.

Mesothorax: unsclerotised. Dorsum with 2 sparse transverse bands of hs; ventrally with a few setae and an lp between each spiracle and mesocoxa (possibly postmesospiracular setae (pm 2 s)). Mesothoracic spiracle (sp 2) small: width of peritreme about 12–14 µm. Furca small but normally developed.

Metathorax: dorsally with a sparse line of hs, representing metatergal setae (mts) and dorsospiracular setae (dss). Ventral part of metapleural ridge (plr 3) short but well-sclerotised; metepisternum (eps 3) absent; metapleural ridge without either a metaprecoxal ridge or an additional short ridge extending ventrally from near coxal articulation. Metepimeron (epm 3) possibly represented by a pair of short sclerotised ridges that extend posteriorly above metacoxae. Ventrally with 1 pair hs anterior sternal setae (amss) and 2 pairs hs posterior metasternal setae (pmss) + 1 lp on each side. Metathoracic spiracle (sp 3): width of peritreme about 10–12 µm, with an associated lp. Metasternum (stn 3) unsclerotised.

Wings and hamulohalteres (h) absent.

Legs: subequal in length. Coxae (cx): I 58–63; II 58–62; III 54–56 µm long; coxa III with about 8 or 9 hs. Trochanter (tr) + femur (fm): I 108; II 96–98; III 100–103 µm long; trochanter III with 5 hs; each trochanter with 2 pairs of roundly oval sensoria, and with strong Y-shaped sclerotised ridges; long trochanter seta not differentiated but seta in this position about 14–16 µm long; femur III with about 6 hs. Tibia (ti): I 81–85; II 75–80; III 88–93 µm; tibia III with 6–8 setae, mainly short and hs, becoming spur-like ventrally towards distal end; all tibiae with 2 apical spurs (tibs); length of longest 12–14 µm. Tarsi (ta) clearly 2 segmented; ta 1 narrow and ring-like; length of both segments (µm): I 45–48 II 45–47; III 47–50 (ratio of length of tibia III to length of tarsus III 1:0.52); tarsus III with 6 or 7 setae, all finely spur-like ventrally; tarsal digitules (tdgt) with blunt or slightly capitate apices and slightly shorter than length of claw. Claws (c) quite long, without a denticle; length: III 17–19 µm; claw digitules (cdt) setose and short.

Abdomen: segments I–VIII: tergites (at) and sternites (as) slightly sclerotised on more posterior segments. Loculate pores (lp) present dorsally on all abdominal segments and ventrally on segment VI (smaller, with 3 loculi); also with an lp laterally on segments I, VI, VII & VIII. Setae present in a single sparse line around each segment, all short, each about 8–10 µm long; with perhaps 8 dorsal abdominal setae (ads), 1 or 2 dorsal pleural setae (dpls), 1 ventral pleural seta (vpls) and 6 ventral abdominal setae (avs) per segment. Each caudal extension/tergite on segment VIII with 3 longer setae, each about 26–44 µm long; tergite VIII with 2 hs dorsal abdominal setae (ads) medially, each about 30 µm long, + 1 or 2 lp; sternite without setae or pores.

Genital segment: penial sheath (ps) broad and approximately triangular; with a finger-like dorsal ridge that narrows to a sharp point; length from anterior margin to apex about 78–83 µm, width at widest point 75–77 µm; finger-like ridge about 33–35 µm wide. Dorsal ridge with a transverse, “new-moon” shaped anal opening (a) dorsally (width about 20 µm), with 3 setae on each side (longest 16 µm) plus 1 pair short setae laterally, each about 7 µm long. Ventrally, aedeagus (aed) emerges through ventral opening; borders of opening quite heavily sclerotised, with 2 pairs of setae, each about 8 µm long, plus another pair of very short setae anteriorly, each about 3 µm long. Aedeagus (aed) strongly curved, perhaps 75 µm long, with a sharp apex; anteriorly, aedeagus bends ventrally and fuses with a short sclerotised basal rod (bra). With several sensilla (psp) along each ps margin near apex.

Comment. The adult male of Rh. kazachstanus appears to be a typical apterous rhizoecine male but differs from the other apterous species seen here in having the following combination of character states: (i) few setae on body; (ii) only hs setae on basal 4 antennal segments; (iii) absence of loculate pores dorsally on thorax; (iv) trochanter with 2 campaniform pores; (v) trochanter with strong Y-shaped sclerotisations; (vi) tarsal digitules with blunt or slightly capitate apices, (vii) 10-segmented antennae, each flagellate segment broadest at distal end, and (viii) a transverse new-moon-shaped anal opening.

Figures

FIGURE 8. Rhizoecus kazachstanus Matesova. Adult male. Where A = hair-like seta; B = fleshy seta, C = loculate pores and K = distal end of posterior leg. For other labels, see under Materials and methods: conventions.