Xylococcus japonicus Oguma, 1926

Hodgson, Chris & Foldi, Imre, 2006, A review of the Margarodidae sensu Morrison (Hemiptera: Coccoidea) and some related taxa based on the morphology of adult males, Zootaxa 1263 (1), pp. 1-250 : 1-250

Xylococcus japonicus Oguma

( Fig. 14 )

Xylococcus alni Oguma, 1919: 78 (Homonym of Xylococcus alni, Florence, 1917 ).

Xylococcus japonicus Oguma, 1926: 101 (replacement name).

Material studied

JAPAN, Soranuma­dake, on Alnus maximuwiczii , 30.viii.1970, Takagi ( BMNH):4/ 4ad ♂♂ (mounted from material labelled Xylococcus japonicus ; in fair condition but all rather poorly cleared, with broken antennae and one damaged in thoracic region).

Mounted material

Large, 3.0–3.7 mm long, 0.8 mm wide across prealare. Body covered in numerous quite short hair­like setae (hs), most about 40–100 m long; smaller hairs (hrs) frequent, 25–40 m long; collared setae (cs) absent; almost all membranous areas with numerous setae, plus loculate pores (lp) (each 8 m wide, mainly with 4 or 5 loculi) on both surfaces of head and thorax but absent from venter of abdomen. Convex pores (cp) absent. Antennae long, flagellar segments all quite narrow, parallel­sided, becoming slightly shorter near apex; each segment with some satellite setae (sats). Sclerotised areas without nodulations. Legs well developed and setose, with many spur­like setae but apparently none bifurcated; tarsi 2 segmented; claws with a minute denticle; claw digitules acute. Abdominal segment I not visible ventrally; abdomen with large tubular ducts with ridged sides on tergites VI and VII; without lateral caudal extensions. Penial sheath more or less terminal.

Head

Triangular in dorsal view, length 318 m, width across compound eyes 600 m. Dorsally: postoccipital suture (pos) broad, extending across posterior part of epicranium (dmep); postocciput (poc) triangular, present posteriorly and varying in size between specimens. Midcranial ridge (mcr) quite broad, extending full length of dorsal part of epicranium (dmep) and fusing with pos posteriorly; sclerotised and longitudinally striated. Postero­medial part of dmep quite strongly sclerotised, becoming membranous anteriorly and laterally. Preocular ridge (procr) probably represented by a short sclerotisation extending medially along dorsal margin of each compound eye from each scape. Dorsal epicranium (dmep) covered in many hs (each 55–85 m long), some hrs (each 25–35 m long) and lp. Laterally: compound eyes (cde) each about 200 m long, with about 150 ommatidia; with a narrow, sclerotised ocular sclerite (ocs) along dorsal and posterior margins, each with a single dorsal ocellus (o), close to postoccipital suture; width of each ocellus 30 m; each ocular sclerite (ocs) with a sclerotised, longitudinal postocular ridge (pocr) along dorsal margin; ventral projection (p) short but distinct and extending ventrally. Ventrally with a strongly sclerotised series of ridges forming a five­armed cross, composed of: (i) a ventral midcranial ridge (vmcr) anteriorly, which fuses posteriorly with (ii) a pair of lateral preocular ridges (procr) and (iii) a pair of preoral ridges (pror) posteriorly; each preoral ridge articulating with a pair of small ventral sclerites (vs) laterally. Ventral part of epicranium (vmep) largely sclerotised postero­medially, becoming membranous anteriorly and laterally. Setal distribution as follows: anteriorly on vmep between mid­cranial ridges and antennae with many setae (hs + a few hrs, as on dmep) + lp; lateral area between preocular (procr) and preoral ridges (pror) with a few hs, mainly medially; area posterior to preoral ridges and around mouth (m) without setae or pores. Cranial apophysis (ca) probably short and broad. Anterior (ata) and posterior tentorial arms (pta) arise just postero­laterally to preoral ridge (pror), meeting tentorial bridge (tb) posteriorly. Ventral sclerites (vs) present just posterior to each compound eye.

Antennae: 10­segmented; length 2.68 mm (ratio of total­body length to antennal length 1:0.8); without a sclerotised articulatory socket with head, but with a strong basal articular process (bap) extending from lateral margin of each scape posteriorly. Scape (scp) 136–145 m long, 100–125 m wide, sclerotised, with many short setae, each about 40–60 m long; without bifurcated setae (bs). Pedicel (pdc) 95–110 m long, 75–80 m wide; with many short setae but no satellite setae (sats), plus 4–6 campaniform sensilla (camp) on dorsal surface. Segments III–IX of flagellum parallel­sided, each about 40–45 m wide, becoming slightly shorter near apex; each segment with many setae, each 60–110 m long, about 1/4 with a satellite seta. Segment X basically similar, possibly narrowing slightly, with 4 bristles (ab) near apex; basiconic sensilla (bass) and capitate setae (caps) absent. Segment lengths (m): III 373, IV 373, V 320–375, VI 340, VII 260–315, VIII 260–290, IX 220 and X 210.

Thorax

Prothorax: neck distinct. Dorsally with a strong pronotal ridge (prnr) which extends uninterrupted across hind part of neck but which does not reach cervical sclerite ventrally. Post­tergites (pt) complex: mainly composed of a longitudinal sclerite, about 125 m long, with a broad area of sclerotisation on either end, anterior sclerotisation appearing similar to an apophysis, about 60 m long and 80 m wide; posterior sclerotisation larger but more diffuse. Laterally with a pair of strong cervical sclerites (cv) which possibly articulate anteriorly with ventral sclerites (vs); cervical sclerite with a large proepimeron (epm 1). Pleural ridge (plr 1) short, extending dorsally from articulation with coxa. Pleural apophysis (pla 1) distinct. Ventrally: prosternum (stn 1) with a well­sclerotised median ridge about 185 m long, which broadens slightly anteriorly but with no obvious sternal apophyses (stn 1 a) posteriorly; transverse ridge absent. Most membranous areas with short setae and lp, as follows: dorsally with a broad group of median pronotal setae (mpns) + lp extending between post­tergites over anterior end of prescutum; with a sparse band of lateral pronotal setae (lpns) just posterior to pronotal ridge (prnr); with separate groups of anterior propleural setae (apl 1 s) + lp and posterior propleural setae (ppl 1 s) on each side; ventrally with a distinct group of anteprosternal setae (astn 1 s) + lp anterior to prosternum (stn 1), and with a group of prosternal setae (stn 1 s) + lp on each side of prosternum. Antemesospiracular setae (asp 2 s) probably absent.

Mesothorax: dorsally: prescutum (prsc) large and approximately oval (length 225 m, width 460 m); mesoprephragma (phr 1) narrow; prescutal ridges (pscr) short; prescutal sutures (pscs) less sclerotised than prescutum; prescutum without prescutal setae (prscs). Scutum (sct) sclerotised throughout; distance from prescutum to scutellum 210 m; with several scutal setae (scts) and a single pore medially but without setae or pores laterally. Scutellum (scl) triangular; without membranous areas laterally; without scutellar setae (scls) or pores; posterior transverse ridge (rd) broad, extending along posterior margin of scutum to posterior notal wing process (pnp). Laterally: prealare (pra) elongate. Tegula sclerite (teg) poorly sclerotised but with a large group of short hs tegular setae (tegs) but no lp. Mesopleural ridge (plr 2) well developed, with a deep pleural apophysis (pla 2). Mesepisternum (eps 2) not nodulated. Mesothoracic spiracles (sp 2) relatively small, outer part of peritreme 70–75 m broad and rather unsclerotised, inner part well sclerotised, 35–40 m wide. Ventrally: basisternum (stn 2) large, length 400 m, width 585 m; with a distinct, complete, sclerotised median ridge (mdr); bounded anteriorly by a welldeveloped marginal ridge (mr) and posteriorly by well­developed precoxal ridges (pcr 2); with a line of short basisternal setae (stn 2 s) along mdr medially plus a small group of setae anteriorly; furca (f) moderately narrow ventrally, slightly waisted, with quite long arms, which diverge strongly; lateropleurite (lpl) indistinct, without an extension from marginal ridge; subepisternal ridge (ser) unusual, broad posteriorly, with a group of setae (lpls). Postmesospiracular setae (pm 2 s) represented by a small group of hs posterior to each anterior spiracle (sp 2); none medially; lp absent. Wing sclerites: apparently similar to other members of this group.

Metathorax: dorsally: metapostnotum (pn 3) apparently absent on some material and well developed on others; when well developed, fused medially; with a group of metatergal setae (mts) + lp extending across segment. Laterally: dorsospiracular setae (dss) + lp in a distinct group laterally. Suspensorial sclerites (ss) present. Pleural ridge (plr 3) well developed; precoxal ridge (pcr 3) well developed and extending about 200 m medio­ventrally; with a moderately deep pleural apophysis (pla 3). Metepisternum (eps 3) lightly sclerotised with a small group of postmetaspiracular setae (eps 3 s); metepimeron (epm 3) represented by a strong sclerotisation extending dorso­posteriorly around metacoxae. Posterior spiracles (sp 3) similar in structure and size to anterior spiracles. Ventrally: metasternum (stn 3) with a triangular sclerotisation medially and large sclerotised apophyses (stn 3 a) laterally. Postmesoprecoxal ridge setae (ppcr 2 s) in small groups anterolaterally; anterior metasternal setae (amss) + few lp in a small group medially; posterior metasternal setae (pmss) (without lp) in a large group medially plus a small group laterally.

Wings: quite large and well developed; each 3.0 mm long, 1.13 mm wide (ratio of length to width 1:0.38; ratio of total­body length to wing length 1:0.9). Subcostal thickening (sclt) well developed; wing anterior to sclt well sclerotised proximally, becoming less so towards wing tip; rest of wing membranous but with large, broken micro­ridges; with a distinct group of 4–9 circular sensoria (sens) near sclt close to wing base, plus a few (12–14?) sens on distal half of wing near subcostal thickening. Alar setae (als) few, perhaps up to 3 or 4 towards base of wing. Radius (rad) vein very faint. Alar lobe (al) represented by a sclerotised fold along proximal posterior margin. Hamulohalteres (h) mainly sclerotised, rather long and narrow, possibly with a sclerotised ridge along anterior margin; length 290–295 m, width 70–80 m; with 2–5 hamuli (ham), each highly curved and probably with a clavate apex.

Legs: metathoracic legs perhaps marginally longest. Coxae (cx) lengths (m): I 266–295; II 260–275; III 260–275; each with some longer setae along lateral margins, longest perhaps 65–85 m; short setae absent basally. Trochanter (tr) + femur (fm) lengths (m): I 515–555; II 480–520; III 535–575; trochanter with several shortish setae + 1 long flagellate seta (length about 165–170 m) plus another seta about half as long; trochanter with a group of 4–6 round campaniform sensilla (camp) on each side; femur with many setae, most shortish but some up to 60 m. Tibia (ti) lengths (m): I 595–650; II 635–650; III 670–705; distal 2/3rds with spur­like setae laterally and ventrally, these replaced by long flagellate setae dorsally; bifurcated setae (bs) absent; with about 10–15 tibial spurs (tibs) distally, all with clavate apices, longest about 35–50 m long. Tarsi (ta) 2 segmented, proximal segment (ta 1) very short and triangular; length of ta 1 + ta 2 (m): I 175–200; II 180–205; III 180–190; with a tarsal campaniform sensillum (camp) (on segment ta 2); without bifurcated setae (bs), all setae short and setose; tarsal spurs (tabs) absent; tarsal digitules (tdgt) probably represented by 2 small, fine setae on dorsal margin near claw. Claws (c) broad, with a minute denticle (cd); claw III about 40–45 m long, with 2 fine setose digitules (cdgt).

Abdomen

Without caudal extensions (ce), margins of segment VII and VIII rounded. Tergites (at) present across all segments, narrowest on anterior segments, covering full width of segments VI–VIII; sternites (as) present across all segments, those on segments VII and VIII covering almost full width of segment; pleurite of segment VIII mildly sclerotised. Dorsal abdominal setae (ads) rather less frequent than ventral abdominal setae (avs); both surfaces with mainly hs (mostly 15–45 m long, but a few avs longer) + a few hrs. Loculate pores (lp) restricted to dorsum, in a line across each segment posterior to most setae. Additionally, on segments VI and VII, each tergite with a broad band of large tubular ducts (tdc) (each about 10 m wide), each pore conical, with a broad inner ductule 20–22 m long and 8 m wide, each ductule with about 8 longitudinal inner ridges, giving it a ridged appearance; with about 31–34 tdc on segment VI, more or less in 2 rows, and with 33–38 on segment VII, more or less in 3 rows. Other pores absent. Tergite of segment VIII without either lp or tubular ducts. Pleural setae divided into dorsal (dps) and ventral (vps) groups; dps in groups with many setae and a few pores; vps in groups on segments I to VI, those on VII and VIII undivided; vps in smaller groups with fewer setae than dps groups, particularly on anterior segments, and all without lp; pleural groups on segments VII and VIII with many setae but no pores. Abdominal spiracles (asp) apparently absent — no tracheae could be detected in abdomen of any specimen (but see under Comment below).

Genital segment: anus (an) present medially above base of penial sheath, anal opening about 85 m wide. Penial sheath (ps) sclerotised, extending posteriorly from beneath segment VIII; about 280–325 m long, 200–225 m wide anteriorly, narrowing to a short, blunt apex posteriorly; with a group of 12 or 13 small hs penial sheath setae (pss) medially (each about 10 m long) on ventral surface anterior to aedeagus, plus a group of 20–25 rather longer setae (each 25–35 m long) on each side; also with a small group of small sensoria (psp) on apex. Aedeagus (aed) sclerotised, broadest anteriorly, narrowing towards bifid apex; 230–250 m long, 103–115 m wide at base; emerging from a ventral slit in penial sheath; with a short sclerotised basal rod (bra) at anterior end of aedeagus, length perhaps 10 m; a long setiferous, eversible endophallus (eph) present internally, perhaps 1300 m long.

Comment

In addition to the above material, 2 other rather poor specimens were also seen (data labelled Kuwania japonica with collection data in Russian (depository: ZIAS)). These specimens appeared to be very similar to the above description, differing mainly in rather more setae and pores. However, perhaps the most significant difference was that there were tracheae present in segments VII and VIII (suggesting the presence of inconspicuous spiracles).

Figures

FIGURE 14. Male Xylococcus japonicus Oguma. Letters as for Fig. 6 except Z = arrangement of spines on endophallus.