Xylococcus castanopsis Wu & Huang, 2017

Dong, Qingang, 2017, First records of the family Xylococcidae (Hemiptera: Coccomorpha) in China, with description of a new species, Zootaxa 4312 (3), pp. 547-556 : 548-555

Xylococcus castanopsis Wu & Huang , sp. nov.

Material examined. Holotype: adult female, on a Slide together with a paratype, holotype on left and paratype on right, Tianluhu ForeSt Park [23.22148° N, 113.4204° E; 180–200 m alt.], Huangpu DiStrict, GuangZhou city, Guangdong Province, P. R. China, under bark of Castanopsis fissa (Fagaceae) , coll. Shaobin Huang, 27.xi.2016. Paratypes: 9 adult femaleS on 6 SlideS, 17 pre-adult femaleS on 4 SlideS and 13 firSt-inStar nymphS on 2 SlideS, Same data aS holotype except collection dateS: 3 adult femaleS and 3 pre-adult femaleS coll. 27.xi.2016; 6 adult femaleS and 14 pre-adult femaleS coll. 24.xii.2006; and firSt-inStar nymphS all killed 27.i.2017.

Etymology. The SpecieS name castanopsis iS a noun in appoSition, referring to the hoSt plant Castanopsis fissa on which the inSectS were found.

Adult female ( FigS 1, 2 , and 9)

Unmounted material. Body of live adult female ovoid to elongate ovoid, broadeSt at thorax, up to 7.6 mm long and 3.6 mm wide, reddiSh, with powdery white wax around vulva and each Spiracular opening, and with SemitranSlucent wax teSt covering almoSt entire body except anal area. Wax teSt probably Secreted by adult female, preadult female, or both.

Slide-mounted material. Body of young adult female ovoid, 3.5–3.9 mm long, 2.6–2.8 mm wide, the holotype 3.5mm long and 2.7mm wide; mature adult female elongate ovoid, up to 7.0–8.0 mm long and 3.0– 3.5 mm wide, broadeSt acroSS thorax, tapering towardS poSterior extremity. Derm membranouS, with denSe tiny papillae and a V- Shaped narrow band of wrinkleS in Submarginal area. Antennae each reduced to an indiStinctly 3-Segmented tubercle, bearing 5 thick and 1 or 2 Slender Setae at apex. EyeSpot Situated lateral to antenna baSe. MouthpartS uSually reduced to veStigeS, but comparatively normal in holotype. LegS abSent. Thoracic SpiracleS Smaller than thoSe on abdomen, each with a Small narrow bar, and a group of 8–10 multilocular poreS cloSe to inner end of atrium. Abdominal SpiracleS numbering eight pairS, each relatively large, with a long tube and an incomplete double band of multilocular poreS cloSe to inner end of atrium; poSteriormoSt pair of SpiracleS Situated cloSe to anal tube. Anal ring not viSible; anal tube Short, truncated cone-Shaped, about 225–313 µm long and a maximum of 150–200 µm wide.

Dorsum. Setae Stiff, thick and briStle-like, abundant and longer on poSteriormoSt three SegmentS; Setae on head each 27–30 µm long, Setae located more poSteriorly 70–75 µm long. DiSc poreS of three typeS: multilocular poreS, large Simple poreS and Small Simple poreS. Multilocular poreS each 10–12 µm long and 5–7 µm wide, with one elliptical inner loculuS and 16 outer loculi, preSent mainly on poSteriormoSt five abdominal SegmentS but with a few on more anterior abdominal SegmentS. Large Simple poreS each 13–15 µm in diameter, diStributed on head, thorax and abdominal SegmentS I–IV; and Small Simple poreS each 2–3 µm in diameter, Scattered on abdomen.

Venter. Setae Slender, each 22–31 µm long, thoSe on margin longer. DiSc poreS of three typeS: multilocular poreS with a bilocular center; multilocular poreS with one elliptical inner loculuS, and large Simple poreS. Multilocular poreS with bilocular centerS, each 10–12 µm long and 5–7 µm wide and with 16 outer loculi, denSely diStributed on medial area from metathorax to vulva. Multilocular poreS with one elliptical inner loculuS, Same aS on dorSum, preSent poSterior to vulva. Large Simple poreS, aS on dorSum, preSent on marginS of head and thorax.

Pre-adult female ( FigS 3, 4 and 10 )

Unmounted material. Pre-adult femaleS found living Singly in bark cavitieS. Body in life oval to pear-Shaped, white to yellowiSh, with poSterior extremity covered by poSterior part of exuviae of previouS inStar. With long, white, hollow, filamentouS wax tube extending from the anal tube to protrude above bark Surface, Serving to carry honeydew excretionS away from body; wall of thiS wax tube made up of, not homogeneouS wax maSS, but of fine wax threadS, Some of which often Separate from the tube wall to curl back towardS the anal opening. BaSal part of wax tube (located beneath bark Surface) Surrounded by thick layer of white woolly wax, probably Secreted by multilocular poreS around anal tube and abdominal SpiracleS; thiS white wax, and almoSt entire body, encloSed by teSt of Semi-tranSlucent wax.

Slide-mounted material. Body oval to pear-Shaped, 2.5–3.2 mm long, 2.0– 2.5 mm wide. Derm uSually areolate, becoming increaSingly Strongly SclerotiSed toward poSterior apex, area around anal tube heavily SclerotiSed. Antennae each reduced to flat oval plate bearing 5 or 6 Stiff Setae. EyeS indiStinct. LegS lacking. MouthpartS developed, labium one-Segmented. Thoracic SpiracleS much reduced, obviouSly Smaller than thoSe on abdomen, each without any bar or diSc poreS within atrium. Abdominal SpiracleS preSent in eight pairS, each Spiracle having a large, elongate tube, with 2–3 bandS of multilocular poreS near inner end of atrium, poSteriormoSt SpiracleS Situated cloSe to anal tube. Anal tube 405–533 µm long and a maximum of 145–200 µm wide, heavily SclerotiSed.

Dorsum. Setae Spine-like, Small, each 5–7 µm long, Scarce on central area, more abundant on Submargin; with 7–9 Slender conical Setae (each 42–50 µm long) preSent on margin on each Side of anal tube. DiSc poreS of four typeS: multilocular poreS, invaginated bilocular poreS, large Simple poreS and Small Simple poreS. Multilocular poreS each elongate oval, 13–15 µm long and 10–12 µm wide, with a bilocular center and 12 or 13 outer loculi, denSely preSent on poSteriormoSt 3 abdominal SegmentS and grouped around each abdominal Spiracle, or forming a denSe band Surrounding all eight pairS of abdominal SpiracleS and anal tube. Invaginated bilocular poreS, each elongate, 8–10 µm long and 6–7 µm wide, invaginated part about 5–6 µm deep, poreS forming tranSverSe bandS or rowS acroSS abdominal tergiteS I–IV. Large Simple poreS, each 10–12 µm in diameter, diStributed in Submarginal band on head and thorax; and Small Simple poreS, each 5–6 µm in diameter, SparSely preSent among invaginated bilocular poreS in tranSverSe bandS.

Venter. Setae Spine-like, Small, Same SiZe aS on dorSum, few in central area, becoming more abundant towardS SubmarginS. An inverted V-Shaped organ (the “brown organ” of Hubbard and Pergande (1898)) preSent medioventrally between fourth and fifth pairS of abdominal SpiracleS. DiSc poreS of four typeS preSent: multilocular poreS, invaginated bilocular poreS, large Simple diSc poreS and Small Simple poreS, all Same aS on dorSum. Multilocular diSc poreS preSent denSely on poSteriormoSt two abdominal SegmentS; invaginated bilocular poreS forming tranSverSe bandS or rowS acroSS abdominal tergiteS I–IV; large Simple poreS diStributed in a Submaginal band on head and thorax; and Small Simple poreS SparSely preSent among invaginated bilocular poreS in tranSverSe bandS.

FirSt-inStar nymph ( FigS 5, 6 and 11 )

Unmounted material. Body of newly hatched nymph elliptical, orange-red but with approximately three poSteriormoSt SegmentS brown due to SclerotiSation. EyeS each viSible aS black Spot; theSe, together with SerieS of black dotS on Submargin of dorSum, forming longitudinal rowS. Mature nymph with long wax tube Secreted from anal tube and about eight pairS of wax threadS, each thread extending from an abdominal Spiracle.

Slide-mounted material. Body broadly elliptical, 0.54–0.59 mm long and 0.36–0.43 mm wide, poSterior apex heavily SclerotiSed, cuticle becoming leSS So anteriorly. SclerotiSed derm of poSterior SegmentS covered with denSe papillae, whereaS derm of unSclerotiZed SegmentS denSely covered with SpinuleS. Antennal baSeS Situated on anterior apex of head, cloSe together but not contiguouS, each antenna Stout, Short (about 60–70 µm long), 6 Segmented, with intermediate SegmentS narrow; apical Segment rounded, bearing 7 Setae including 3 fleShy Setae and 1 longer briStle-like Seta; Segment V with 2 Setae including 1 fleShy Seta; Segment II with a Single SenSory pore. EyeS preSent. ClypeuS well developed; labium very reduced, 1-Segmented or not viSible; retracted StyletS very long, extending backward and curling into 3 or 4 loopS in abdomen. LegS Slender; each trochanter comparatively long, with proximal half Strongly narrowed, with 1 pair of placoid SenSilla on each Surface and a long Seta, about 71 µm long; each claw Slender, with a diStinct denticle near tip of plantar Surface; claw digituleS each with apex knobbed, exceeding tip of claw. LengthS of hind leg SegmentS: coxa 30–33 µm, trochanter 35–40 µm, femur 97–123 µm, tibia 92–113 µm, tarSuS 87–105 µm, claw 22–25 µm. Ratio of lengthS of hind trochanter + femur to tibia + tarSuS 1: 1.34–1.36, the ratio of length of tibia to tarSuS 1: 0.93–0.95. Thoracic SpiracleS each with faintly developed bar and atrium containing 1 complex multilocular pore (with 3 central loculi). Abdominal SpiracleS numbering eight pairS, each Spiracle larger than thoracic Spiracle, with deeply invaginated cup containing 1 complex multilocular pore about 6 µm in diameter, with 4 (occaSionally 3) central loculi and 12 or 13 outer loculi. Anal tube 70–88 µm long and 27–40 µm wide, located at poSterior end. A pair of apical Setae preSent, each 107–118 µm long.

Dorsum. Setae briStle-like, even conical, longer and Stronger towardS margin, each 10–13 µm long, forming 10 longitudinal lineS. DiSc poreS of four typeS preSent: multilocular poreS, large Simple poreS, Small Simple poreS and invaginated 4- (uSually) or 5-locular poreS. Multilocular poreS each with Simple center and 8 peripheral loculi, each pore 5–7 µm in diameter; prothorax and meSothorax each with 1 pore on each Side; metathorax and abdominal SegmentS I–VII each with 2 poreS on Submedian area; abdominal SegmentS I–VIII each with 1 pore on each Side near margin. Invaginated 4- or 5-locular poreS, each 10–13 µm in diameter, 15–18 µm deep, preSent on margin of abdomen, each Side with 7 poreS. Large Simple poreS, each 7.0–7.5 µm in diameter, totaling two pairS, preSent Singly on Submedian area of prothorax and meSothorax. Small Simple poreS, each 4–5 µm in diameter, preSent on abdominal SegmentS I–VIII, each Segment with 1 pore on each Side near margin.

Venter. With about 10 longitudinal lineS of Setae, thoSe in medianmoSt 2 lineS each long, thin and hair-like, 45– 50 µm long; remaining Setae Same Shape and SiZe aS thoSe on dorSum. DiSc poreS of four typeS preSent, all Same aS on dorSum. Multilocular poreS preSent on marginS of abdominal SegmentS I–VIII, each Segment with 1 on each Side (apart from Segment VII with 2). Large Simple diSc pore: only 1 preSent medially on metathorax. Small Simple poreS preSent on abdominal SegmentS I–VIII, each Segment with 1 on each Side near margin. Invaginated 4- or 5- locular poreS alSo preSent on marginS of abdomen, each Side with 7 poreS, Situated among abdominal SpiracleS. Three large cicatriceS preSent, each 12–15 µm in diameter, arranged longitudinally along midline of abdominal SegmentS VI–VIII.

Eggs. Pale yellow or yellow in colour, each about 0.5 mm long and 0.35 mm wide.

Adult male. Not found.

Biology. Xylococcus castanopsis sp. nov. waS found in foreStry StandS compoSed of Lithocarpus silvicolarum (Hance) Chun , Castanopsis chinensis (Spreng.) Hance, C. fissa , C. hystrix Mig. (Fagaceae) , Canarium album (Lour.) RaeuSch. (BurSeraceae) , Aporusa dioica (Roxb.) Muell. Arg. , Glochidion puberum (L.) Hutch. ( Euphorbiaceae ), Ardisia quinquegona Bl. (MyrSinaceae) , Schima Sp. (Theaceae) , Ligustrum sinense Lour. (Oleaceae) , Ilex pubescens Hook et Arn. (Aquifoliaceae) , Schefflera octophylla (Lour.) HarmS ( Araliaceae ), Cinnamomum burmanni (NeeS et T. NeeS) Blume ( Lauraceae ) and Dicranopteris dichotoma (Thunb.) Berhn.

(Gleicheniaceae). Out of the above 14 plant SpecieS, the Scale waS detected only on Castanopsis fissa . It infeSted mainly plantS over 30 yearS old, but could alSo be found on young treeS. On each plant, the inSectS live under the bark on the trunk and partS of the rootS about 40 cm above the ground.

The adult femaleS can be found from late November to late December, and give birth probably parthenogenetically, depoSiting the eggS beneath the abdomen. A Single female can lay 67–268 eggS (mean 176, n=6). One adult female waS obServed to project her abdominal SegmentS out of the bark cavity ( Fig. 8 ), Seemingly calling for an adult male, but neither adult maleS nor male pupae were found during about two monthS of inveStigation.

Remarks. Of the three extant SpecieS currently included in Xylococcus ( X. filiferus Löw, 1882 , X. japonicus Siraiwa, 1939 and X. quercicola DanZig, 1980 ), only the deScriptionS of the adult femaleS of X. filiferus and X. japonicus are available becauSe X. quercicola waS deScribed from a pre-adult female. Adult female X. castanopsis sp. nov. differ from thoSe of X. filiferus in having multilocular poreS with 1 or 2 inner loculi, no tiny SenSory poreS toward the baSe of the antennae and in lacking the SclerotiZed plate on the poSterior apex of body; in contraSt, adult female X. filiferus have multilocular poreS with 3 or 4 inner loculi, 4 tiny SenSory poreS near the baSe of each antenna, and the poSterior apex of body uSually haS a SclerotiZed plate from the pre-adult adherent ( MorriSon, 1928). It can be diStinguiShed from X. japonicus by the abSence of legS and the preSence of an unSclerotiZed anal tube, whereaS X. japonicus haS legS, although they are reduced to globular protuberanceS, and the anal tube iS Short and SclerotiZed.

The pre-adult femaleS of all three previouSly known extant SpecieS of Xylococcus have been deScribed. ThoSe of X. filiferus can be eaSily diStinguiShed from the other SpecieS (according to deScriptionS and illuStrationS by MorriSon (1928) and KoSZtarab and KoZár (1988) by the preSence of a circular plate at the poSterior apex of body and the preSence of trilocular poreS ventrally. The remaining three SpecieS are morphologically too Similar to Separate, although the illuStration of the bilocular poreS of X. japonicus and X. quercicola in DanZig (1980a) ShowS that they are flat, whereaS they are invaginated on X. castanopsis sp. nov.

The firSt-inStar nymph of only X. filiferus haS been well deScribed previouSly ( MorriSon 1928). The differenceS between the firSt-inStar nymphS of X. filiferus and X. castanopsis are: X. filiferus haS invaginated bilocular poreS on the margin of the body, and large Simple poreS are abSent from both the dorSum and venter of the thorax; whereaS X. castanopsis haS invaginated quadrilocular poreS on the margin of the body and large Simple poreS are preSent on both the dorSum and venter of the thorax.

It iS poSSible that X. castanopsis sp. nov. and X. quercicola are conSpecific. The pre-adult femaleS of both SpecieS are very Similar and the hoSt plantS of both belong to the family Fagaceae . However, here we conSider X. castanopsis to be new to Science becauSe: 1) X. quercicola iS found in the RuSSian Far EaSt, whereaS X. castanopsis sp. nov. iS only known from South China, and 2) X. quercicola infectS Quercus mongolica , whereaS X. castanopsis liveS on Castanopsis fissa . The plant genuS Castanopsis (D. Don) Spach containS about 120 SpecieS, diStributed in tropical and Subtropical regionS of ASia, with 58 SpecieS in China and diStributed South to the YangtZe River, whereaS Q. mongolica iS reStricted to north of YangtZe River ( Huang et al., 1999). NevertheleSS, whether X. castanopsis iS a valid SpecieS or Synonym of X. quercicola will only be determined after collection of the adult female of X. quercicola in RuSSia or if molecular analySeS of material of both SpecieS can be compared.

Figures

FIGURE 10. Morphology of pre-adult female of Xylococcus castanopsis sp. nov. (A) antenna; (B) large simple pore; (C) thoracic spiracle; (D) small simple pore; (E) invaginated bilocular pores; (F) Pergande’s “ brownish organ ”; (G) multilocular pore with bilocular center; (H) seta on abdomen; (I) anal tube and adjacent region; (J) abdominal spiracle; (K) seta on head.

FIGURE 11. Morphology of first-instar nymph of Xylococcus castanopsis sp. nov. (A) antenna; (B) thoracic spiracle; (C) hind claw; (D) single ventral cicatrix; (E) multilocular pore; (F) seta on dorsal abdomen and ventral margin; (G) anal tube; (H) invaginated quadralocular pore; (I) small simple pore; (J) abdominal spiracle; (K) large simple pore; (L) spinules on derm; (M) seta on head; (N) papillae on derm.

FIGURES 1 – 8. Habit photographs. Xylococcus castanopsis sp. nov. Adult female, (1) dorsal view and (2) ventral view. Preadult female and its wax secretions, (3) with wax intact and (4) with ventral part of wax test removed. First-instar nymphs, showing wax secretions: (5) newly hatched and (6) older. Adult female, (7) producing eggs under her ventral surface, and (8) projecting her abdominal segments out of the bark cavity.